Understanding Surge Protector Specs for the Computer Age

[kiki_danc]

No it won't. It will be suppressed to between 420V and 1200V per the datasheet you supplied in post #52 (https://www.physicsforums.com/threads/surge-protector-specs.955697/page-3#post-6063218) or between 420V and 2000V per the datasheet you supplied in post #26 (https://www.physicsforums.com/threads/surge-protector-specs.955697/page-2#post-6060374)

Ideally, the most protection is to use 3 MOVs at the primary and 3 at the load. This will catch both common mode and line-to-line surges.

View attachment 231464

This is the part that I want to understand from the beginning. If your power supply is line to line and your equipment is line to line.. how can common mode occurs when your equipment is not grounded.. and even if there is surge at line to ground.. how can it damage the equipment?

Then do the same at the primary using 240Vac MOVs. Of course you can use pre-built SPDs.

So in the primary. I'd put 320 Vac MOV across the 220 volts line to line.. and 150 Vac MOV from line 1 to ground and line 2 to ground? meaning I'd be using 5 pieces of 150 Vac MOV and one 320 Vac MOV?

By the way, decide what you want to happen when an SPD fails shorted.

• Shut off power to the load when they fail, thereby protecting it from further surges.
• Disconnect the MOVs from the circuit while keeping power to the load, but they no longer protect the load.

When most SPDs fail they fail shorted, and will trip the circuit breaker feeding them to remove power.
The one you showed in post #52 is the second option, it keeps power to the load and blows an internal fuse to disconnect a shorted MOV.

You need a fuse or circuit breaker in the power feed to the SPD for the first option.
But don't try to add an external fuse to get the effect of the second option. The fuse sizing and design is a science in itself. Let the manufacturer do it.

Can we put this project to bed yet?

Cheers,
Tom

What does the datasheet say about the type 3 you are proposing? I've lost track of all of the ones we've discussed.

Let's take this 320Vac SPD...

If the surge is 6000 volts, 3000 ampere at 8/20 microsecond.. VPR is 1200 volts...
However if the surge is only say 1300 volts.. 500 ampere at 8/20 microsecond.. won't the VPR become say 100 volts only or so?

Edit: I mean won't the voltage becomes 100 volts only or so way below the VPR rating?

 

[kiki_danc]

This is the part that I want to understand from the beginning. If your power supply is line to line and your equipment is line to line.. how can common mode occurs when your equipment is not grounded.. and even if there is surge at line to ground.. how can it damage the equipment?So in the primary. I'd put 320 Vac MOV across the 220 volts line to line.. and 150 Vac MOV from line 1 to ground and line 2 to ground? meaning I'd be using 5 pieces of 150 Vac MOV and one 320 Vac MOV?

Let's take this 320Vac SPD...

View attachment 231466

If the surge is 6000 volts, 3000 ampere at 8/20 microsecond.. VPR is 1200 volts...
However if the surge is only say 1300 volts.. 500 ampere at 8/20 microsecond.. won't the VPR become say 100 volts only or so?

Edit: I mean won't the voltage becomes 100 volts only or so way below the VPR rating?

See this illustration for the above...

So type 3 would only have very low voltage way below the VPR.. why is this wrong?

(also note the 420 V you were mentioning were really DC in the specs)

 

[Tom.G]

This is the part that I want to understand from the beginning. If your power supply is line to line and your equipment is line to line.. how can common mode occurs when your equipment is not grounded.. and even if there is surge at line to ground.. how can it damage the equipment?

Consider a nearby lightning strike that puts 6000V on the power line to ground. Much equipment is rated perhaps 600V or so from line to chassis, the the chassis is now at 6000V, and so is everything in it and connected to it. Is there anything near enough to the equipment that a 6000V spark can jump to? For instance the insulation in a transformer would likely break down if anything on its secondary is grounded or near a ground or a large conducting surface. If the transformer is mounted in an electrical box, the box would likely be grounded and the an arc would jump to the transformer core, to the box, to ground. If a person happens to be in contact with the equipment, he/she is now at 6000V; is the floor wet, person touching another piece of equipment at the same time?

So in the primary. I'd put 320 Vac MOV across the 220 volts line to line.. and 150 Vac Move from line 1 to ground and line 2 to ground? meaning I'd be using 5 pieces of 150 Vac MOV and one 320 Vac MOV?

This one I will back off from a bit, I tend to think how the wiring HERE is done. The SPDs you had installed in the breaker box were a very good start, leave them in. Now add a line-to-line SPD at the transformer primary.

Let's take this 320Vac SPD...

In line 4 of the table see "MCOV (VAC/VDC)" it says (320/420). That is saying you can put 420VDC on the input continuously and the device will ignore it, that it will not conduct.

Now go to line 7, "Voltage protection rating" "VPR" this shows "<1.2kV" meaning that the maximum clamping voltage is not greater than 1200V.

However if the surge is only say 1300 volts.. 500 ampere at 8/20 microsecond.. won't the VPR become say 100 volts only or so?

So type 3 would only have very low voltage way below the VPR.. why is this wrong?

That is an ASSUMPTION on your part. The manufacturer is only guaranteeing that the output is less than 1.2kV. How much equipment do you want to gamble that your assumption is more accurate than the manufacturers explicit statement?

Cheers,
Tom

 

[kiki_danc]

Consider a nearby lightning strike that puts 6000V on the power line to ground. Much equipment is rated perhaps 600V or so from line to chassis, the the chassis is now at 6000V, and so is everything in it and connected to it. Is there anything near enough to the equipment that a 6000V spark can jump to? For instance the insulation in a transformer would likely break down if anything on its secondary is grounded or near a ground or a large conducting surface. If the transformer is mounted in an electrical box, the box would likely be grounded and the an arc would jump to the transformer core, to the box, to ground. If a person happens to be in contact with the equipment, he/she is now at 6000V; is the floor wet, person touching another piece of equipment at the same time?

Thanks for this info. In my country, most electrician never connect metallic chassic to ground. They just cut the ground wire.. and before this week I didn't know the purpose was to trip the breaker in case line touches metallic chassic and not electrocute the person (most electricians ignore this). From now on. I'll ensure all metallic chassic is grounded.. we never did it before. Even the refrigerator in my house and aircon are not grounded at present.

This one I will back off from a bit, I tend to think how the wiring HERE is done. The SPDs you had installed in the breaker box were a very good start, leave them in. Now add a line-to-line SPD at the transformer primary.

The prosurge local supplier was afraid the 320Vac SPD may explode if put line to line 240 volts.. do you have reference it can be put line to line? I thought only line to ground.

In line 4 of the table see "MCOV (VAC/VDC)" it says (320/420). That is saying you can put 420VDC on the input continuously and the device will ignore it, that it will not conduct.

Now go to line 7, "Voltage protection rating" "VPR" this shows "<1.2kV" meaning that the maximum clamping voltage is not greater than 1200V.
That is an ASSUMPTION on your part. The manufacturer is only guaranteeing that the output is less than 1.2kV. How much equipment do you want to gamble that your assumption is more accurate than the manufacturers explicit statement?

Cheers,
Tom

That's why I want to understand the microscopic physics of MOVs. If you pass 1300vac voltage to it.. would it suppress the 1300vac to become 100 volts or would it become 1200vac? Understanding the microphysics may give us a clue.. so far what have you read about this?

 

[kiki_danc]

Thanks for this info. In my country, most electrician never connect metallic chassic to ground. They just cut the ground wire.. and before this week I didn't know the purpose was to trip the breaker in case line touches metallic chassic and not electrocute the person (most electricians ignore this). From now on. I'll ensure all metallic chassic is grounded.. we never did it before. Even the refrigerator in my house and aircon are not grounded at present.
The prosurge local supplier was afraid the 320Vac SPD may explode if put line to line 240 volts.. do you have reference it can be put line to line? I thought only line to ground.
That's why I want to understand the microscopic physics of MOVs. If you pass 1300vac voltage to it.. would it suppress the 1300vac to become 100 volts or would it become 1200vac? Understanding the microphysics may give us a clue.. so far what have you read about this?

Btw.. I assume you understand the difference between VPR and SVR (Suppressed Voltage Rating). Here is a brief summary in my own words. VPR is a UL 1449 Third Edition term, UL 1449 Second edition uses SVR (Suppressed Voltage Rating).
SVR is measured using surge pulse of 6000 volts, 500 ampere and 8/20 microsecond. The SVR output is about 400 volts. In UL 1449 third edition, they use surge pulse of 6000 volts, higher 3000 ampere and 8/20 microsecond producing 1200 volts let-through. That is why in 3rd edition, the 400 became higher at 1200 Volts. This proves that 1200 volts is the not the average or ceiling but only if the input is 6000V, 3000A at 8/20 us. If the input is just 6000 volts, 500 ampere at similar 8/20 microsecond, SVR becomes mere 400 volts. So I'm assuming if the input pulse is just 1200 volts, 1000 ampere at 8/20 microsecond, the SVR/VPR would be 100 volts. This is reasonable but like you said the manufacturing didn't test it at 1200 volts, 500 ampere input. Hmm... Maybe to be safe, you have the point about using 120 volt AC.

About leaving the original as it is. Remember the 320Vac Mcov gets added twice to become 640 Vac (from 220 ac line to line).. so it starts to clamp at 640 Vac. Shouldn't I use 150 Vac Mcov instead? If it clamps at 640 Vac.. VPR or SVR would increase too... why do you say retain it... you are relying on the secondary 120 volts to lower it?

 

[kiki_danc]

Yes, the Red looks to be the long-lost third wire. And the diagram in post #85 is similar to what I suspected when you said only 2 wires, I just wasn't familiar with the Open Delta configuration. (I learned something new. GREAT!)

I looked carefully a while ago. It's really only 2 lines coming from high tension, the 3rd line is not connected. See:

It's a unique open delta with only 2 wires coming from high tension, the third wire supposed use ground (perhaps this is why we got shock from touching nails embedded in concrete inside the building??) Here are the illustration, explanations and discussions:

https://www.practicalmachinist.com/...nd-vfd/three-phase-only-two-wires-wtf-103191/
​

"Around here, many farms and other low-demand users of three phase get an arrangement called "open delta".

The utility provides two of the three phases using two hot wires and a ground. Two transformers are used, usually one larger one (typically 25 or 50 KVA), and one smaller one (typically 5 or 10 KVA).

The larger transformer has the secondary center tapped, and this tap is grounded. Let's call the ends of the secondary phase "A" and Phase "C". One end of the secondary of the smaller transformer is then tied to phase "A", with the other end of the small transformer secondary being phase "B".

At the panel, the user gets two legs 120 volts neutral to ground (Phase A and Phase C), and one "wild leg" (Phase B) which is 208 volts neutral to ground. All the 120 volt single phase loads are tapped off phase A and Phase C (hence the use of a larger transformer for those two). Usually any 240 volt single phase loads will also go from phase A to phase C as well. You can use normal three phase panels, but you have to identify the "wild leg" wires with an orange stripe at each point.

All three legs are used to provide 240 volts three-phase to the three phase loads on the site.

Overhead high-voltage lines on farms are usually bare ACSR (aluminum conductor with steel reinforcement), not copper. It is usual to run a hot line and a ground for single phase, or two hot lines and a ground for open-delta three phase.

Underground high-voltage is typically supplied with a fancy coaxial cable, with the center conductor supplying the high volts and the shield grounded. Two of these, connected to two transformers, could definitely supply you with three phase. "

But I still don't comprehend why you won't supply 120V thru a transformer to the 24VDC supply. The 240V SPDs won't keep the spikes below the 300V input rating of the supply. That was a limitation you stated earlier in the thread. Can you explain?

Cheers,
Tom

 

[kiki_danc]

No it won't. It will be suppressed to between 420V and 1200V per the datasheet you supplied in post #52 (https://www.physicsforums.com/threads/surge-protector-specs.955697/page-3#post-6063218) or between 420V and 2000V per the datasheet you supplied in post #26 (https://www.physicsforums.com/threads/surge-protector-specs.955697/page-2#post-6060374)

Ideally, the most protection is to use 3 MOVs at the primary and 3 at the load. This will catch both common mode and line-to-line surges.

View attachment 231464

About your figure above where the MOV is put line to line. I think not all SPDs can do that. For example, the specs of Prosurge has the following table:

You see. There is no L-L (Line to Line). It's only L-N, L-G, N-G protection modes listed. I think Prosurge is made in china. I'm looking for one made in USA. So in your work hope you can see what brand is the best your engineering crew has encountered. Right now I saw this good model at amazon.https://www.amazon.com/gp/product/B013WINLIO/?tag=pfamazon01-20 It can handle line to line.

So I hope you or others can share some good models too. So we can be sure to get the best. Thanks.

Then do the same at the primary using 240Vac MOVs. Of course you can use pre-built SPDs.

By the way, decide what you want to happen when an SPD fails shorted.

• Shut off power to the load when they fail, thereby protecting it from further surges.
• Disconnect the MOVs from the circuit while keeping power to the load, but they no longer protect the load.

When most SPDs fail they fail shorted, and will trip the circuit breaker feeding them to remove power.
The one you showed in post #52 is the second option, it keeps power to the load and blows an internal fuse to disconnect a shorted MOV.

You need a fuse or circuit breaker in the power feed to the SPD for the first option.
But don't try to add an external fuse to get the effect of the second option. The fuse sizing and design is a science in itself. Let the manufacturer do it.

Can we put this project to bed yet?

Cheers,
Tom

 

[kiki_danc]

Consider a nearby lightning strike that puts 6000V on the power line to ground. Much equipment is rated perhaps 600V or so from line to chassis, the the chassis is now at 6000V, and so is everything in it and connected to it. Is there anything near enough to the equipment that a 6000V spark can jump to? For instance the insulation in a transformer would likely break down if anything on its secondary is grounded or near a ground or a large conducting surface. If the transformer is mounted in an electrical box, the box would likely be grounded and the an arc would jump to the transformer core, to the box, to ground. If a person happens to be in contact with the equipment, he/she is now at 6000V; is the floor wet, person touching another piece of equipment at the same time?

Everything you mentioned yesterday finally sinked in. So let's wrap up by the following questions I need to know.

1. In the US, your equipment is connected Line to Neutral and since Neutral is connected to your Ground at service entrance, then all you need are common mode SPD and not really normal mode, isn't it? (but I seem to see specs that line to neutral is called normal mode.. does it mean in the US you need to put line to line SPDs in addition to line to ground SPDs too?? In other words, is Line to Neutral also considered as Line-to-Line, why? If yes, then how about if you are connecting 120v to 120v to get 240v, then it's called Normal Mode II or Line to Line II since you already have one Line to Line if you consider Line to Neutral as Line to Line? And you will get 3 sets of SPDs in equipment in your country?

In our country. Our power is bonafide line to line, so we need normal mode (or L-L) spd. About the common mode SPD, you are saying above that equipment connected to ground won't get damaged even by 6000V strike but the concern is only the person standing nearby. Hence, if my equipments are located in isolated place without people nearby.. then I can just put one 320V Line to Line at primary side of transformer and one 150Vac Line to Line at secondary side of transformers without needing to put any Line to Ground SPDs. Is this correct?

Or did you mean that if a chassis to ground is exposed to 6000V surge, the surge can still fly to the circuit? If it only concerns protection none-existing people then I'd save 4 pieces of SPDs connecting line to ground by just using 2 line to line SPDs at primary and secondary..

2. When you have a 6000V surge at the primary side of the transformer, would it become 3000V surge at the secondary side of the step down transformer (220V to 110V)? But because there is big impedance in the transformer, I guess the surge can become 8000V.. have you thought of this? So the benefit of using transformer is just so as to use lower voltage SPD to get lower clamping voltage right?

3. I think tapping just line to ground to get 120 volts is the fastest way. I'd only need to do it for one breaker at a minor panel (not the main panel). I may be able to convince city hall I won't buy appliance in the US because many local appliance now offers 120 volts. However, I'm now very concerned of my unique 2 transformer open delta which connects to 2 primary phases and not 3 with the third one something to do with ground (as detailed in 2 messages prior to this). Is my ground contaminated? Won't this affect my connecting line to ground to get 120 volts without needing transfomers?

4. Those are the important questions for now that I need to know to decide best course of actions (I have to decide by today so we don't have to continue discussing and wasting your previous time). Anyway In my country, the supplier earns 5 times the actual cost of the unit abroad. This is because of the scarcity of SPDs in my country and SPDs seem to be very good business opportunity. Maybe let's be business partners for this, Tom... Lol.. Thanks :)

This one I will back off from a bit, I tend to think how the wiring HERE is done. The SPDs you had installed in the breaker box were a very good start, leave them in. Now add a line-to-line SPD at the transformer primary.In line 4 of the table see "MCOV (VAC/VDC)" it says (320/420). That is saying you can put 420VDC on the input continuously and the device will ignore it, that it will not conduct.

Now go to line 7, "Voltage protection rating" "VPR" this shows "<1.2kV" meaning that the maximum clamping voltage is not greater than 1200V.
That is an ASSUMPTION on your part. The manufacturer is only guaranteeing that the output is less than 1.2kV. How much equipment do you want to gamble that your assumption is more accurate than the manufacturers explicit statement?

Cheers,
Tom

 

[kiki_danc]

I've been searching for almost half day for this important information opening and reading dozens of pages but can't seem to find the definite answer and it's literally giving me headaches so hope we can discuss the microphysics of MOVs. As you can see. Most information gives illustration of SPDs being connected with ground at one terminal. This is because in the US, line to line of 240 volts is seldom use. Hence you always see this illustration even in brochures and technical paper.

What would happen if you connect any SPD line to line? For example.. in the US, if per phase you had 60 volts giving line to line of 120 volts, if you connect any regular 150Vac SPD line to line.. would it still work or does SPD needs to have one terminal at ground? What I want to know is.. do line to line SPDs need to be specially constructed? What do you think?

In the two siemens products at amazon. Even though there is L-L. It's not directly connected.. only their more expensive product has discrete L-L but with dedicated panel so you can't buy these separately. Full details at https://w3.usa.siemens.com/powerdis...alog/Documents/2017/SF-17-Sect-10-ALL-web.pdf

The only available SPDs now that you can put Line to Line is the normal SPDs. So would the MOV element function the same if it has line on both terminal compared to only one? After googling for 5 hours. I gave up looking for answer in the net. Theoretically what do you think? (if Line to Ground can be omitted as I asked in my separate message (hope you can answer it there). Then I'd just focus on L-L connection using my existing 2 pieces 320Vac SPD and putting them at line to line at breaker and near equipment for temporary solution while awaiting the 150Vac (if the supplier still decided to give it to me free after I convinced them clamping voltage can increase as you verified).

Btw.. about why my neutral or ground has current and we get slight jolt when we touch concrete with screws.. I think it' because of unbalanced 3 phase (the other owners in building don't want to balance load).. I read this at wiki's section on "ground and neutral".

"In a three-phase linear circuit with three identical resistive or reactive loads, the neutral carries no current. The neutral carries current if the loads on each phase are not identical. In some jurisdictions, the neutral is allowed to be reduced in size if no unbalanced current flow is expected. If the neutral is smaller than the phase conductors, it can be overloaded if a large unbalanced load occurs. "

After getting reply to this and the two messages above. Let's wrap up this thread as it's already time consuming and very long. And I'll give you double Like or 5 stars if there is such. Thanks a lot Tom!

 

[Tom.G]

1. In the US, your equipment is connected Line to Neutral and since Neutral is connected to your Ground at service entrance, then all you need are common mode SPD and not really normal mode, isn't it? (but I seem to see specs that line to neutral is called normal mode.. does it mean in the US you need to put line to line SPDs in addition to line to ground SPDs too?? In other words, is Line to Neutral also considered as Line-to-Line, why? If yes, then how about if you are connecting 120v to 120v to get 240v, then it's called Normal Mode II or Line to Line II since you already have one Line to Line if you consider Line to Neutral as Line to Line? And you will get 3 sets of SPDs in equipment in your country?

The philosophy seems to be to "cover all possibilities" as to how many and where the MOVs are connected. If all possible connections are made in the SPD then all the wires are at (nearly) the same voltage during a surge and the possibility of damage is reduced. As one example, if there are two or more SPDs that may be using a common Neutral (or a common Ground), then one of them may suppress a surge, causing the Neutral (or Ground) wire to momentarily rise by a few hundred volts. Another SPD on the circuit would sees this, and one or more of its MOVs will conduct to keep all the wires it is connected to at the appropriate relative voltages. Note that the supply wires at this second device may rise by a few hundred volts in this case, but the voltage difference between them will remain relatively constant, and will track the rise on the Neutral (or Ground) wire.

Hence, if my equipments are located in isolated place without people nearby.. then I can just put one 320V Line to Line at primary side of transformer and one 150Vac Line to Line at secondary side of transformers without needing to put any Line to Ground SPDs. Is this correct?

Well, not quite. Consider a Common Mode surge on the transformer primary. Because the primary and secondary winding are close to each other (often the primary will be wound right on top of the secondary) the is capacitive coupling between the two windings, just as if you put a small value capacitor from the primary to the secondary. The secondary, if it is not grounded, could then rise to the same voltage as the primary Common Mode surge. That's why power wiring, even from a transformer secondary on a power pole, has one wire grounded. (Sometimes, when a transformer fails, the primary shorts to the secondary. For instance you wouldn't want the 4kv to 16kV on the power pole transformer on your 240V service.)

Getting a shock when touching a Ground wire and a concrete wall means that one of them is connected to a hot wire somewhere! I would vote that your "Ground" is not really a Ground. Something is (dangerously) mis-wired somewhere. The "unbalanced 3 phase" and Neutral current is based on a 3-phase 4-wire configuration, 3-phase Wye connected source (120/208 or 240/416 as used in the USA).

3. I think tapping just line to ground to get 120 volts is the fastest way. I'd only need to do it for one breaker at a minor panel (not the main panel). I may be able to convince city hall I won't buy appliance in the US because many local appliance now offers 120 volts. However, I'm now very concerned of my unique 2 transformer open delta which connects to 2 primary phases and not 3 with the third one something to do with ground (as detailed in 2 messages prior to this). Is my ground contaminated? Won't this affect my connecting line to ground to get 120 volts without needing transfomers?

See my comment above.

Considering that the rest of your wiring is 'unknown' (reference 'Its 3 wire', 'no, it's only 2 wire', 'maybe the 3rd wire is ground', 'I get a shock when touching the Ground wire and the concrete wall' ), your best bet is a 240/120 transformer. If you can find an actual, confirmed Ground, connect one of the transformer secondary leads to it. That takes care of the capacitive coupling between windings. Then you can then use a 120V L-L SPD at the load. A 3 SPD on the primary side would be the safest if you have an actual Ground available.

The only available SPDs now that you can put Line to Line is the normal SPDs. So would the MOV element function the same if it has line on both terminal compared to only one?

Yes. Just be sure that if it is in a metal case that the case is not connected to one of the lead wires. The MOVs in an SPD only care about the difference in voltage between their terminals, they dont' care if say one wire has 1,000,000 volts and the other side has 1,000,100 volts; it just knows there is 100 volts across it.

The prosurge local supplier was afraid the 320Vac SPD may explode if put line to line 240 volts.. do you have reference it can be put line to line? I thought only line to ground.

Look at line 4 of the data sheet. It shows Maximum voltage. There is no minimum input voltage anywhere. And the physics of an MOV do not show any minimum either. (I think the 'local supplier' is in need of an education beyond how to take peoples money.)

Here is one link about Varistors, which is the general term for the devices in SPDs:
https://www.electronics-tutorials.ws/resistor/varistor.html
Above was found with: https://www.google.com/search?&q=how+mov+varistor+works

Here is a drawing from the above article showing the construction of a MOV.
https://www.electronics-tutorials.ws/resistor/res72.gif
The Zinc Oxide grains are close enough to each other that they are in light electrical contact, with very little current able to flow between them; probably due to the oxide layer on their surfaces. Higher voltages are able to break down this oxide layer and allow more current to flow. That's how they suppress surges, by conducting the higher voltages, usually to ground, but blocking current when only the lower normal operating voltage is present.

I've probably missed a few of your many questions, hopefully these answers covered your major issues.

Cheers,
Tom

 

[kiki_danc]

The philosophy seems to be to "cover all possibilities" as to how many and where the MOVs are connected. If all possible connections are made in the SPD then all the wires are at (nearly) the same voltage during a surge and the possibility of damage is reduced. As one example, if there are two or more SPDs that may be using a common Neutral (or a common Ground), then one of them may suppress a surge, causing the Neutral (or Ground) wire to momentarily rise by a few hundred volts. Another SPD on the circuit would sees this, and one or more of its MOVs will conduct to keep all the wires it is connected to at the appropriate relative voltages. Note that the supply wires at this second device may rise by a few hundred volts in this case, but the voltage difference between them will remain relatively constant, and will track the rise on the Neutral (or Ground) wire.Well, not quite. Consider a Common Mode surge on the transformer primary. Because the primary and secondary winding are close to each other (often the primary will be wound right on top of the secondary) the is capacitive coupling between the two windings, just as if you put a small value capacitor from the primary to the secondary. The secondary, if it is not grounded, could then rise to the same voltage as the primary Common Mode surge. That's why power wiring, even from a transformer secondary on a power pole, has one wire grounded. (Sometimes, when a transformer fails, the primary shorts to the secondary. For instance you wouldn't want the 4kv to 16kV on the power pole transformer on your 240V service.)

While waiting for my free 150Vac MOVs from prosurge.. I can wire them one 320Vac at breaker line to line and one 320 Vac at load line to line.. I'd try transformers when the 150Vac arrive. So if I'll not use transformers.. the equipments won't be damaged by surge from line to ground but only affecting person that may be near it?

Getting a shock when touching a Ground wire and a concrete wall means that one of them is connected to a hot wire somewhere! I would vote that your "Ground" is not really a Ground. Something is (dangerously) mis-wired somewhere. The "unbalanced 3 phase" and Neutral current is based on a 3-phase 4-wire configuration, 3-phase Wye connected source (120/208 or 240/416 as used in the USA).

The ground in my main breakers are really neutral wires connecting directly to the transformers. We don't have separate ground wires. Now I don't think the hot wire is connected to the concrete or neutral because it can spark immediately. It's not all the time.. sometimes only.. so I wonder if open delta unbalance loads can cause the neutral to have current too?

See my comment above.

Considering that the rest of your wiring is 'unknown' (reference 'Its 3 wire', 'no, it's only 2 wire', 'maybe the 3rd wire is ground', 'I get a shock when touching the Ground wire and the concrete wall' ), your best bet is a 240/120 transformer. If you can find an actual, confirmed Ground, connect one of the transformer secondary leads to it. That takes care of the capacitive coupling between windings. Then you can then use a 120V L-L SPD at the load. A 3 SPD on the primary side would be the safest if you have an actual Ground available.Yes. Just be sure that if it is in a metal case that the case is not connected to one of the lead wires. The MOVs in an SPD only care about the difference in voltage between their terminals, they dont' care if say one wire has 1,000,000 volts and the other side has 1,000,100 volts; it just knows there is 100 volts across it. Look at line 4 of the data sheet. It shows Maximum voltage. There is no minimum input voltage anywhere. And the physics of an MOV do not show any minimum either. (I think the 'local supplier' is in need of an education beyond how to take peoples money.)

Here is one link about Varistors, which is the general term for the devices in SPDs:
https://www.electronics-tutorials.ws/resistor/varistor.html
Above was found with: https://www.google.com/search?&q=how+mov+varistor+works

Here is a drawing from the above article showing the construction of a MOV.
https://www.electronics-tutorials.ws/resistor/res72.gif
The Zinc Oxide grains are close enough to each other that they are in light electrical contact, with very little current able to flow between them; probably due to the oxide layer on their surfaces. Higher voltages are able to break down this oxide layer and allow more current to flow. That's how they suppress surges, by conducting the higher voltages, usually to ground, but blocking current when only the lower normal operating voltage is present.

I've probably missed a few of your many questions, hopefully these answers covered your major issues.

Cheers,
Tom

You've covered so much that I am so thankful of you. Say what would happen to the MOV or SPD if it would be connected in series between live lines? I won't try this but just wanted to know what would theoretically happen?

 

[kiki_danc]

The philosophy seems to be to "cover all possibilities" as to how many and where the MOVs are connected. If all possible connections are made in the SPD then all the wires are at (nearly) the same voltage during a surge and the possibility of damage is reduced. As one example, if there are two or more SPDs that may be using a common Neutral (or a common Ground), then one of them may suppress a surge, causing the Neutral (or Ground) wire to momentarily rise by a few hundred volts. Another SPD on the circuit would sees this, and one or more of its MOVs will conduct to keep all the wires it is connected to at the appropriate relative voltages. Note that the supply wires at this second device may rise by a few hundred volts in this case, but the voltage difference between them will remain relatively constant, and will track the rise on the Neutral (or Ground) wire.Well, not quite. Consider a Common Mode surge on the transformer primary. Because the primary and secondary winding are close to each other (often the primary will be wound right on top of the secondary) the is capacitive coupling between the two windings, just as if you put a small value capacitor from the primary to the secondary. The secondary, if it is not grounded, could then rise to the same voltage as the primary Common Mode surge. That's why power wiring, even from a transformer secondary on a power pole, has one wire grounded. (Sometimes, when a transformer fails, the primary shorts to the secondary. For instance you wouldn't want the 4kv to 16kV on the power pole transformer on your 240V service.)

Getting a shock when touching a Ground wire and a concrete wall means that one of them is connected to a hot wire somewhere! I would vote that your "Ground" is not really a Ground. Something is (dangerously) mis-wired somewhere. The "unbalanced 3 phase" and Neutral current is based on a 3-phase 4-wire configuration, 3-phase Wye connected source (120/208 or 240/416 as used in the USA).See my comment above.

Considering that the rest of your wiring is 'unknown' (reference 'Its 3 wire', 'no, it's only 2 wire', 'maybe the 3rd wire is ground', 'I get a shock when touching the Ground wire and the concrete wall' ), your best bet is a 240/120 transformer. If you can find an actual, confirmed Ground, connect one of the transformer secondary leads to it. That takes care of the capacitive coupling between windings. Then you can then use a 120V L-L SPD at the load. A 3 SPD on the primary side would be the safest if you have an actual Ground available.Yes. Just be sure that if it is in a metal case that the case is not connected to one of the lead wires. The MOVs in an SPD only care about the difference in voltage between their terminals, they dont' care if say one wire has 1,000,000 volts and the other side has 1,000,100 volts; it just knows there is 100 volts across it. Look at line 4 of the data sheet. It shows Maximum voltage. There is no minimum input voltage anywhere. And the physics of an MOV do not show any minimum either. (I think the 'local supplier' is in need of an education beyond how to take peoples money.)

Here is one link about Varistors, which is the general term for the devices in SPDs:
https://www.electronics-tutorials.ws/resistor/varistor.html
Above was found with: https://www.google.com/search?&q=how+mov+varistor+works

Here is a drawing from the above article showing the construction of a MOV.
https://www.electronics-tutorials.ws/resistor/res72.gif
The Zinc Oxide grains are close enough to each other that they are in light electrical contact, with very little current able to flow between them; probably due to the oxide layer on their surfaces. Higher voltages are able to break down this oxide layer and allow more current to flow. That's how they suppress surges, by conducting the higher voltages, usually to ground, but blocking current when only the lower normal operating voltage is present.

I've probably missed a few of your many questions, hopefully these answers covered your major issues.

Cheers,
Tom

By the way. When the SPD is connected to ground at one end.. the current can escape to the ground during surge. But if it is connected line to line with no ground.. and it shorted.. where will the current go? The breaker may trip but how does it suppress the surge.. can the current make the MOV hot by somehow the MOV trapping the electrons in the oxide?

 

[Tom.G]

You've covered so much that I am so thankful of you. Say what would happen to the MOV or SPD if it would be connected in series between live lines? I won't try this but just wanted to know what would theoretically happen?

If you mean in series like a switch:

• If the supply voltage is below the turn-on voltage (suppression voltage) then it will act like a switch that is turned off.
• If the supply voltage is above the turn-on voltage (suppression voltage) then the load will see the supply voltage minus the suppression voltage.

Also realize that the suppression voltage increases somewhat as the current thru the MOV increases.
You could probably get away with trying this using a very small load like a 25W light bulb. The MOV will be thermally limited in continuous use like this so be careful it doesn't get too hot.

 

[Tom.G]

By the way. When the SPD is connected to ground at one end.. the current can escape to the ground during surge. But if it is connected line to line with no ground.. and it shorted.. where will the current go? The breaker may trip but how does it suppress the surge.. can the current make the MOV hot by somehow the MOV trapping the electrons in the oxide?

A Normal mode (L-L) surge will be suppressed by the MOV acting like a rather poor wire but shorting the lines together enough to load down the voltage surge due to the impedance of the wires; which is its normal usage.

If it is a Common mode surge, the MOV will have no effect and the voltage on both wires will rise by whatever the surge voltage is.

 

[kiki_danc]

A Normal mode (L-L) surge will be suppressed by the MOV acting like a rather poor wire but shorting the lines together enough to load down the voltage surge due to the impedance of the wires; which is its normal usage.

If it is a Common mode surge, the MOV will have no effect and the voltage on both wires will rise by whatever the surge voltage is.

Most configuration uses common mode where the MOV is connected to ground.. when there is surge.. it will short circuit.. decreasing the voltage.. why did you say the MOV will have no effect, in what context?

By the way I wonder how you know so much about SPDs.. have you worked in the industry before or are all scientists (like Witten) familiar with it?

 

[Tom.G]

in what context?

In the context of the question you asked, connected L-L.

 

[kiki_danc]

In the context of the question you asked, connected L-L.

Ah ok. Now that ties up the loose ends (pun intended)…

Thanks 10^137 Tom :)

 

[kiki_danc]

I let electrician connect the spd 320 line to line to the 220 volts line at breaker.. so far it didnt smoke hurray.. btw isn't it if an spd fails. It would short so can this trip the breaker and no adverse effect.on the equipment?

And. I forgot to ask two other things. If I'd put the 320Vac SPD near equipment line to line temporary (without transformer since I am still waiting for my 150Vac SPD and I know transformer can make up for the impedance), should the 10 meters wires from breaker be maintained for the impedance or does this only work for line to ground type 3?

And lastly what would happen if I put 2 pcs of 320Vac SPDS at breaker line to line, what would be the effect of this 2 pcs for the surge as these 2 interact with the surge? Would the surge current be divided among them or VPR would increase or decrease or any unexpected adverse effect?

 

[Tom.G]

btw isn't it if an spd fails. It would short so can this trip the breaker and no adverse effect.on the equipment?

See post #98, repeated here:

By the way, decide what you want to happen when an SPD fails shorted.

• Shut off power to the load when they fail, thereby protecting it from further surges.
• Disconnect the MOVs from the circuit while keeping power to the load, but they no longer protect the load.

When most SPDs fail they fail shorted, and will trip the circuit breaker feeding them to remove power.
The one you showed in post #52 is the second option, it keeps power to the load and blows an internal fuse to disconnect a shorted MOV.

You need a fuse or circuit breaker in the power feed to the SPD for the first option.
But don't try to add an external fuse to get the effect of the second option. The fuse sizing and design is a science in itself. Let the manufacturer do it.

To expand on that, most type 3 SPDs I've seen are of the second design; they disconnect themselves while continuing to supply the load. This is especially true of those that have an indicator showing good/bad status, such as an LED that is normally lit and goes off when the MOVs have failed.

If I'd put the 320Vac SPD near equipment line to line temporary (without transformer since I am still waiting for my 150Vac SPD and I know transformer can make up for the impedance), should the 10 meters wires from breaker be maintained for the impedance or does this only work for line to ground type 3?

If it is a type 3, yes; doesn't matter what the internal configuration is.

And lastly what would happen if I put 2 pcs of 320Vac SPDS at breaker line to line, what would be the effect of this 2 pcs for the surge as these 2 interact with the surge? Would the surge current be divided among them or VPR would increase or decrease or any unexpected adverse effect?

Surge will be divided between them, VPR will decrease, no adverse effects. (except to your wallet if you don't have an extra laying around)

Cheers,
Tom

 

[kiki_danc]

See post #98, repeated here:

To expand on that, most type 3 SPDs I've seen are of the second design; they disconnect themselves while continuing to supply the load. This is especially true of those that have an indicator showing good/bad status, such as an LED that is normally lit and goes off when the MOVs have failed.If it is a type 3, yes; doesn't matter what the internal configuration is.Surge will be divided between them, VPR will decrease, no adverse effects. (except to your wallet if you don't have an extra laying around)

Cheers,
Tom

But if you put 2 SPDs at breaker panel side by side with only 1 inch wire between the 2 SPDs, there is no 10 meter wires to make the impedance, how would that affect the second SPD at breaker panel. You said the SPD type 3 10 meters away need to make use of the 10 meter impedance to lower the voltage.. and in the 2 SPDs side by side at panel breaker.. won't the second SPD beside it not be able to lower the voltage (or if it can, to what degree)?

 

[Tom.G]

They will be working in parallel, sharing the load of the surge; like a game of tug-of-war where you have several people pulling on opposite ends of a rope. The more people pulling together the more effective they are.

The type 3 specification (UL1449) says must be 10 meters of wire. Probably to limit the current thru the SPD. I haven't read the spec for type 2, but since they are intended for use in the breaker box they probably have a higher peak current capability, counting on the larger but longer service entrance wires for voltage drop. I think I gave the link to the UL page in an earlier post, why don't you read it and see what you can find out about type 2?

Cheers,
Tom

 

[kiki_danc]

They will be working in parallel, sharing the load of the surge; like a game of tug-of-war where you have several people pulling on opposite ends of a rope. The more people pulling together the more effective they are.

The type 3 specification (UL1449) says must be 10 meters of wire. Probably to limit the current thru the SPD. I haven't read the spec for type 2, but since they are intended for use in the breaker box they probably have a higher peak current capability, counting on the larger but longer service entrance wires for voltage drop. I think I gave the link to the UL page in an earlier post, why don't you read it and see what you can find out about type 2?

Cheers,
Tom

I have read it over and over. But remember my situation is i'll put a high surge capacity (50kA) Type 2 at the equipment 5 meters away. Since my SPD has high surge current capacity, then it's not sensitive to the current. But I'm concerned about impedance and planning to add 5 meters of wire in loop (see pic below) just to meet the 10 meters. And I'm asking to what extend can the SPD lower the voltage for 10 meters impedance versus just 1 inch wire (between 2 SPDs put side by side at breaker panel where the 2nd farther SPD 1 inch away would only see the 1 inch wire impedance and not see the longer service entrance wire). May I know the formula to relate voltage and impedance and why longer wires can bring the voltage down? Thank you.

https://standardscatalog.ul.com/standards/en/standard_1449

1 Scope
1.1 These requirements cover enclosed and open-type Surge Protective Devices (SPDs) designed for repeated limiting of transient voltage surges as specified in the standard on 50 or 60 Hz power circuits not exceeding 1000 V and for PV applications up to 1500 V dc and designated as follows:

Type 1 – One port, permanently connected SPDs, except for watt-hour meter socket enclosures, intended for installation between the secondary of the service transformer and the line side of the service equipment overcurrent device, as well as the load side, including watt-hour meter socket enclosures and Molded Case SPDs intended to be installed without an external overcurrent protective device. Type 1 SPDs for use in PV systems can be connected between the PV array and the main service disconnect.

Type 2 – Permanently connected SPDs intended for installation on the load side of the service equipment overcurrent device; including SPDs located at the branch panel and Molded Case SPDs.

Type 3 – Point of utilization SPDs, installed at a minimum conductor length of 10 meters (30 feet) from the electrical service panel to the point of utilization, for example cord connected, direct plug-in, receptacle type and SPDs installed at the utilization equipment being protected. See marking in 80.3. The distance (10 meters) is exclusive of conductors provided with or used to attach SPDs.

Type 4 Component Assemblies – Component assembly consisting of one or more Type 5 components together with a disconnect (integral or external) or a means of complying with the limited current tests in 44.4.

Type 1, 2, 3 Component Assemblies – Consists of a Type 4 component assembly with internal or external short circuit protection.

Type 5 – Discrete component surge suppressors, such as MOVs that may be mounted on a PWB, connected by its leads or provided within an enclosure with mounting means and wiring terminations.

1.2 Except as indicated in 1.3, the products covered by this Standard are rated and intended for connection to circuits or supply sources having nominal voltage ratings as specified in Table 44.1.

1.3 A product intended for connection to an ac circuit or supply source other than that specified in 1.2 may be examined and tested in accordance with the intent of the requirements in this standard and, if found to be substantially equivalent, may be judged to comply with this Standard.

1.4 These requirements cover cord-connected direct plug-in, and permanently connected SPDs intended for indoor and outdoor use in accordance with the National Electrical Code, ANSI/NFPA-70.

1.5 These requirements do not cover the interconnection of multiple field installed SPDs.

1.6 These requirements cover SPDs that may include components specifically intended to function as filters for conducted electromagnetic interference (EMI) or noise, in addition to limiting transient voltage surges. See Section 26.

1.7 These requirements cover SPDs employing circuit components intended to provide secondary protection for telephone communication circuits and circuit components intended to protect data communication or fire alarm circuits. See Section 27.

1.8 These requirements cover SPDs employing antenna connections for audio-video products. See Section 28.

1.9 An SPD that has a battery backup feature or other uninterruptible power supply equipment shall also comply with the applicable requirements in the Standard for Uninterruptible Power Supply Equipment, UL 1778. See Section 30.

1.10 These requirements cover SPDs/Panelboard Extension Modules. These products shall also comply with the Standard for Panelboards, UL 67. See Section 31.

1.11 These requirements do not evaluate the effect of SPDs on connected loads, the effect of SPDs on harmonic distortion of the supply voltage, the degree of attenuation provided by SPDs, nor the adequacy of the voltage protection rating of SPDs to protect specific connected equipment from upset or damage.

1.12 This standard does not cover cord connected or direct plug-in SPDs intended for use with medical equipment. Medical equipment is typically intended for use in General Patient Care Areas or Critical Patient Care Areas as defined by Article 517 of the National Electrical Code for Health Care Facilities. SPDs intended for such use shall comply with the requirements of the Standard for Safety of Medical Electrical Equipment, Part 1: General Requirements, UL 60601-1, and the Standard for Safety Requirements for Medical Electrical Systems, IEC 60601-1-1.

1.13 An SPD intended to serve as an outlet cover plate or outlet box hood shall comply with the requirement for faceplates in the Standard for Cover Plates for Flush Mounted Wiring Devices,UL 514D.

1.14 An SPD intended for use in a Lightning Protection System (LPS) shall comply with the Surge Protection requirements in the Standard for Installation Requirements for Lightning Protections Systems, UL 96A.

1.15 A Type 3 SPD may employ additional low voltage supplementary circuitry to power a USB charger.

1.16 A cord-connected or direct plug-in Type 3 SPD may employ a replaceable or non-replaceable rechargeable battery to power a USB output circuit.

1.17 A direct plug-in SPD employing more than two receptacles shall also comply with the applicable requirements in the Standard for Current Taps and Adapters, ANSI/UL 498A.

1.18 A cord-connected SPD employing more than two receptacles shall also comply with the applicable requirements in the requirements in the Standard for Relocatable Power Taps, UL 1363 or the Standard for Furniture Power Distribution Units, UL 962A.

 

[kiki_danc]

I have read it over and over. But remember my situation is i'll put a high surge capacity (50kA) Type 2 at the equipment 5 meters away. Since my SPD has high surge current capacity, then it's not sensitive to the current. But I'm concerned about impedance and planning to add 5 meters of wire in loop (see pic below) just to meet the 10 meters. And I'm asking to what extend can the SPD lower the voltage for 10 meters impedance versus just 1 inch wire (between 2 SPDs put side by side at breaker panel where the 2nd farther SPD 1 inch away would only see the 1 inch wire impedance and not see the longer service entrance wire). May I know the formula to relate voltage and impedance and why longer wires can bring the voltage down? Thank you.

View attachment 231595

https://standardscatalog.ul.com/standards/en/standard_1449

To reword my inquiry above in case you didn't get the central concern. For the 2 SPD put side by side with 1 inch distance between them in the main breaker panel. Would the 2nd SPD 1 inch away from the first SPD see the 1 inch wire or the entire service entrance wire for the impedance? If it can see the entire service entrance wire.. how come the SPD 5 meters away can't see the entire service entrance wire for the impedance? I'm preparing to add 5 meters but just wondering of the behavior of the SPD 1 inch away from first SPD and the SPD 5 meters away from first SPD.

 

[kiki_danc]

To reword my inquiry above in case you didn't get the central concern. For the 2 SPD put side by side with 1 inch distance between them in the main breaker panel. Would the 2nd SPD 1 inch away from the first SPD see the 1 inch wire or the entire service entrance wire for the impedance? If it can see the entire service entrance wire.. how come the SPD 5 meters away can't see the entire service entrance wire for the impedance? I'm preparing to add 5 meters but just wondering of the behavior of the SPD 1 inch away from first SPD and the SPD 5 meters away from first SPD.

View attachment 231596

Or if the rewording above is still confusing.. see the following illustration:

Assuming there is long service entrance wire and SPD 1 can see it... can SPD 2 one inch away from SPD 2 also see the long service entrance wire impedance? If yes.. how come the SPD 3 can't see the longer service entrance wire impedance?

 

[kiki_danc]

Here's a last question Tom (I promise last question because if we go on more and it will produce critical information not many know.. I'm afraid ignorant SPD suppliers may print all of these making them as quick manual for newbie technicians and my security would be compromised since I have many pictures (Most technicians and suppliers don't know this level of information.. for example my supplier told me he has never tried connecting it line to line and always line to ground since it's how they are commonly installed). So okay if you don't give detailed impedance computations. I'd ask this in separate message in other forums or website to dilute the information.

The last question concerns neutral and ground. I plan to purchase this Siemens 120/240V Split Phase 140,000 A surge protector to put line to line besides the prosurge 320Vac I already installed at breaker panel... but I saw at amazon this review: https://www.amazon.com/dp/B013WINMK6/?tag=pfamazon01-20

amazon review:
"Falsely reports ground to neutral problem By Mark M Harbaughon August 16, 2018
The SPD falsely reported a neutral to gnd problem when none existed. A replacement SPD functions properly and does not report a neutral to ground problem."

And in the product literature it is mentioned:

"The SPD is equipped with an audible alarm which will sound in the event of an alarm condition. This indicates a problem with the SPD which requires further evaluation. There is no test or silence switch. De-energizing the SPD will silence the alarm."

So I'm afraid the alarm may sound continuously if it detects something wrong with my ground.

Something is wrong in our ground or neutral because in my country compared to US, (to summarize briefly) we used your split phase 120/240V phase to phase power system to power our buildings with government complied 240 volts. We don't use phase to neutral 120 volts nor use neutral to ground bonding at panel. Therefore the neutral in the Open Delta transformer is connected to our breaker panel as ground (no separate ground). In most homes without Open Delta transformations. I have confirmed there is not even ground or neutral wires coming to the house. For the particular Open Delta supplied building like mine. Our ground is neutral wire connected to the transfomers. Now since we don't have separate neutral and ground. I'm afraid the Siemens device will keep sounding alarm (as well as all other brands of 120/240v split phase surge protectors at amazon). Any idea how to make proper neutral and ground so it can be connected to the proper Siemens leads without sounding fault alarm.. this is illustrated thus:

Again my transformer Neutral is used as Ground in our building without separate ground. If our aircon housing is connected to neutral in the transformers. What problem would this produce and what is meant by ground to neutral fault in the US that can cause problem with the Siemens Device.

btw.. does this user review makes any sense: https://shedheads.net/whole-house-surge-protectors
"Sizing a surge protector can be a challenge. The larger capacity models can protect against the largest surges, but let small ones pass. This means that some of your smallest, most delicate electronics can be damaged. Meanwhile, most of the smaller surge protectors aren’t sized to handle massive surges.
This siemens model is the exception. It has a “three stage” protection system that enables it to catch all surges, both large and small.
"

Do you believe it's true that Sizing a surge protector can be a challenge. That larger capacity models can protect against the largest surges, but let small ones pass? I haven't read this in surge literature.. is there a basis for it?

Again thanks very much and this is really my last inquiry for security concerns.

 

[Tom.G]

Would the 2nd SPD 1 inch away from the first SPD see the 1 inch wire or the entire service entrance wire for the impedance?

The second SPD will see the entire service entrance wire for the impedance. (plus a tiny bit from the extra 1 inch)

how come the SPD 5 meters away can't see the entire service entrance wire for the impedance?

It can. The problem arises due to the relatively low service entrance impedance and the lower current capability of the type 3 SPDs.

what is meant by ground to neutral fault in the US that can cause problem with the Siemens Device.

In the U.S., the Ground and Neutral are connected together. Apparently the Siemens SPD checks this connection and complains if they are not connected.

Any idea how to make proper neutral and ground so it can be connected to the proper Siemens leads without sounding fault alarm.

This refers to the SPDs in the breaker box. The type 3 at the equipment, if any, is addressed below.
1) CHECK WITH YOUR POWER COMPANY to see if this is both safe and legal before you do this step. This suggestion is based on the U.S. National Electrical Code (NEC) and may not be appropriate where you are located.
From a safety and effectiveness standpoint, drive an 8 foot ground rod into the Earth near the breaker panel. Then run a wire not smaller than the service entrance conductors from the ground rod to the breaker box. Make the wire run as straight as possible and any needed bends should be gentle (large bend radius), not sharp 'square corners'. The gentle bends present a better path for high current lightning strikes, sharp bends tend to induce any high voltages to jump to other nearby conductors.

• 
  Now you have two options:
  • Connect the new Ground wire to the Neutral in your breaker box AND to the ground wire of the SPD.
  • Connect the new Ground wire only to the ground wire of the SPD.

2) If the above is not possible/practicle, to disable the alarm on the SPD, connect the SPD ground wire to the same place the SPD neutral wire is connected. (not ideal, but better than nothing.)

That larger capacity models can protect against the largest surges, but let small ones pass? I haven't read this in surge literature.. is there a basis for it?

Look at the VPR and the maximum Amperage of type 1 or 2 SPDs versus the type 3 SPDs.

* to summarize: type 1 or 2 SPD at breaker box. Type 3 at the equipment with either a transformer or at least 10 meters of wire from the type 1 or 2. If there is a type 3 at the equipment, connect its ground wire to the new Ground wire from the 8 foot Ground rod referenced above for the breaker box.
Documentation for the FS140 (https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43434) states on page 2 (pg 4 of the .PDF) that the voltage drop of a surge pulse is 175V per foot (574V per meter). That means the 10 meters of wire can drop the surge voltage by 5,740V provided there is a surge suppressor at that 10 meter position.

Cheers,
Tom

 

[kiki_danc]

The second SPD will see the entire service entrance wire for the impedance. (plus a tiny bit from the extra 1 inch)

It can. The problem arises due to the relatively low service entrance impedance and the lower current capability of the type 3 SPDs.

I was asking this yesterday to possibly justify not adding 5 meters of wire to existing 5 meters to comply with UL minimum 10 meters to equipment.. but 2 hours before your reply before we already installed it with electrician:

It's Prosurge 50,000A surge capable Type 2 with 5 meters of wires in loop added to existing 5 meters making up 10 meters from main breaker panel and besides the equipments (the green wire is existing and I know I made wrong color choice years ago, the black wire is the additional 5 meters). This is pictured energized so all is well. Now this question is just to clarify above and academic (since I already installed it). You said type 3 can see the service entrance wires which has low impedance and type 3 supposedly have lower surge current capability. I don't get it. If it has type 3 with low surge current capability.. why can't low impedance be enough for it? Isn't it low current and low impedance go together? Because you seemed to be implying low surge current capability type 3 needs high impedance?

And for my actual implementation (temporary as I'm waiting for 150Vac SPD and 220V-110V transformer implementation hence the no wire clamp is just temporary), I didn't use low surge current capable type 3 but the samehigh 50,000A surge current which I now put both at breaker panel and 10 meters away from it near equipment. So how does this change your statement about "The problem arises due to the relatively low service entrance impedance and the lower current capability of the type 3 SPDs" as it pertains to whether the type 3 can see the service entrance wires. With my high current surge type 3.. what would it see? Should the 10 meters requirement be theoretically increased or decreased if high surge current type 3 is used?

Thanks.

In the U.S., the Ground and Neutral are connected together. Apparently the Siemens SPD checks this connection and complains if they are not connected.This refers to the SPDs in the breaker box. The type 3 at the equipment, if any, is addressed below.
1) CHECK WITH YOUR POWER COMPANY to see if this is both safe and legal before you do this step. This suggestion is based on the U.S. National Electrical Code (NEC) and may not be appropriate where you are located.
From a safety and effectiveness standpoint, drive an 8 foot ground rod into the Earth near the breaker panel. Then run a wire not smaller than the service entrance conductors from the ground rod to the breaker box. Make the wire run as straight as possible and any needed bends should be gentle (large bend radius), not sharp 'square corners'. The gentle bends present a better path for high current lightning strikes, sharp bends tend to induce any high voltages to jump to other nearby conductors.

• 
  Now you have two options:
  • Connect the new Ground wire to the Neutral in your breaker box AND to the ground wire of the SPD.
  • Connect the new Ground wire only to the ground wire of the SPD.

2) If the above is not possible/practicle, to disable the alarm on the SPD, connect the SPD ground wire to the same place the SPD neutral wire is connected. (not ideal, but better than nothing.)Look at the VPR and the maximum Amperage of type 1 or 2 SPDs versus the type 3 SPDs.

* to summarize: type 1 or 2 SPD at breaker box. Type 3 at the equipment with either a transformer or at least 10 meters of wire from the type 1 or 2. If there is a type 3 at the equipment, connect its ground wire to the new Ground wire from the 8 foot Ground rod referenced above for the breaker box.
Documentation for the FS140 (https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43434) states on page 2 (pg 4 of the .PDF) that the voltage drop of a surge pulse is 175V per foot (574V per meter). That means the 10 meters of wire can drop the surge voltage by 5,740V provided there is a surge suppressor at that 10 meter position.

Cheers,
Tom

 

[kiki_danc]

I was asking this yesterday to possibly justify not adding 5 meters of wire to existing 5 meters to comply with UL minimum 10 meters to equipment.. but 2 hours before your reply before we already installed it with electrician:

View attachment 231644

It's Prosurge 50,000A surge capable Type 2 with 5 meters of wires in loop added to existing 5 meters making up 10 meters from main breaker panel and besides the equipments (the green wire is existing and I know I made wrong color choice years ago, the black wire is the additional 5 meters). This is pictured energized so all is well. Now this question is just to clarify above and academic (since I already installed it). You said type 3 can see the service entrance wires which has low impedance and type 3 supposedly have lower surge current capability. I don't get it. If it has type 3 with low surge current capability.. why can't low impedance be enough for it? Isn't it low current and low impedance go together? Because you seemed to be implying low surge current capability type 3 needs high impedance?

And for my actual implementation (temporary as I'm waiting for 150Vac SPD and 220V-110V transformer implementation hence the no wire clamp is just temporary), I didn't use low surge current capable type 3 but the samehigh 50,000A surge current which I now put both at breaker panel and 10 meters away from it near equipment. So how does this change your statement about "The problem arises due to the relatively low service entrance impedance and the lower current capability of the type 3 SPDs" as it pertains to whether the type 3 can see the service entrance wires. With my high current surge type 3.. what would it see? Should the 10 meters requirement be theoretically increased or decreased if high surge current type 3 is used?

Thanks.

Let me reword this last inquiry about impedance as I'm quite confused by it and can't shake the feelings.

1. You said the service entrance has low impedance... this means the SPD 1 & 2 are not so effective in lowering the voltage because it needs high impedance?

2. You need 10 meters to SPD 3 at equipment so the SPD3 there can lower the voltage more effectively.. but can't the type 1 or 2 at breaker entrance sees the 10 meters wire from it to the SPD 3 or does it only see the low impedance at service entrance wire?

3. Does this mean service entrance wire should be long so it would become high impedance for the Spd 1 & 2 to decrease the voltage more effectively...

4. What's so confusing is why is impedance needed to lower voltage. If you have a stand alone SPD with high voltage introduced to it.. the mere fact the MOV conducts means the voltage difference is lowered.. why is impedance important? Wikipedia defines impedance as: Electrical impedance is the measure of the opposition that a circuit presents to a current when a voltage is applied. So I can't quite get why it is need to bring the voltage down. I'm quite dumb in this thing. Appreciate a million for your help Tom!

 

[kiki_danc]

The second SPD will see the entire service entrance wire for the impedance. (plus a tiny bit from the extra 1 inch)

It can. The problem arises due to the relatively low service entrance impedance and the lower current capability of the type 3 SPDs.

Googling has led me to electrical engineering section in stack exchange.. I think the details of the above is because if the wires are not 10 meters.. there is not enough inductance to limit the current. Not only this. But the clamping won't work well without the impedance in the wires. So I guess it has double purpose. I guess this answers my own questions in the message prior to this. I'll grill the electrical engineers there if I have more detail questions about the technical aspects of it.

About the transformer. You may make sense about lowering down 220 volts to 110 volts to get lower clamping voltage. I wonder if all those countries with 220 volts also use 110 step down transformer to get lower clamping voltage? Well. I have difficulty finding plug in SPDs made in USA (I don't want made in china anymore). Most are integrated. So I wonder what would happen if I used transformer and get 110 volts line to line.. Would the dozens of intergrated SPDs made in US able to distinguish between whether the 110 volts came from line to neutral (in the US power system) or came from line to line (in my country)? If not. Then I can get any products there.. if it can distinguish.. then I'm stuck to plug in stand alone SPDs. Your last answer here would help me decide whether to get the dozens of available integrated SPDs like the Siemens or others. As always thanks you so much Tom.

In the U.S., the Ground and Neutral are connected together. Apparently the Siemens SPD checks this connection and complains if they are not connected.This refers to the SPDs in the breaker box. The type 3 at the equipment, if any, is addressed below.
1) CHECK WITH YOUR POWER COMPANY to see if this is both safe and legal before you do this step. This suggestion is based on the U.S. National Electrical Code (NEC) and may not be appropriate where you are located.
From a safety and effectiveness standpoint, drive an 8 foot ground rod into the Earth near the breaker panel. Then run a wire not smaller than the service entrance conductors from the ground rod to the breaker box. Make the wire run as straight as possible and any needed bends should be gentle (large bend radius), not sharp 'square corners'. The gentle bends present a better path for high current lightning strikes, sharp bends tend to induce any high voltages to jump to other nearby conductors.

• 
  Now you have two options:
  • Connect the new Ground wire to the Neutral in your breaker box AND to the ground wire of the SPD.
  • Connect the new Ground wire only to the ground wire of the SPD.

2) If the above is not possible/practicle, to disable the alarm on the SPD, connect the SPD ground wire to the same place the SPD neutral wire is connected. (not ideal, but better than nothing.)Look at the VPR and the maximum Amperage of type 1 or 2 SPDs versus the type 3 SPDs.

* to summarize: type 1 or 2 SPD at breaker box. Type 3 at the equipment with either a transformer or at least 10 meters of wire from the type 1 or 2. If there is a type 3 at the equipment, connect its ground wire to the new Ground wire from the 8 foot Ground rod referenced above for the breaker box.
Documentation for the FS140 (https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43434) states on page 2 (pg 4 of the .PDF) that the voltage drop of a surge pulse is 175V per foot (574V per meter). That means the 10 meters of wire can drop the surge voltage by 5,740V provided there is a surge suppressor at that 10 meter position.

Cheers,
Tom

 

[kiki_danc]

Googling has led me to electrical engineering section in stack exchange.. I think the details of the above is because if the wires are not 10 meters.. there is not enough inductance to limit the current. Not only this. But the clamping won't work well without the impedance in the wires. So I guess it has double purpose. I guess this answers my own questions in the message prior to this. I'll grill the electrical engineers there if I have more detail questions about the technical aspects of it.

About the transformer. You may make sense about lowering down 220 volts to 110 volts to get lower clamping voltage. I wonder if all those countries with 220 volts also use 110 step down transformer to get lower clamping voltage? Well. I have difficulty finding plug in SPDs made in USA (I don't want made in china anymore). Most are integrated. So I wonder what would happen if I used transformer and get 110 volts line to line.. Would the dozens of intergrated SPDs made in US able to distinguish between whether the 110 volts came from line to neutral (in the US power system) or came from line to line (in my country)? If not. Then I can get any products there.. if it can distinguish.. then I'm stuck to plug in stand alone SPDs. Your last answer here would help me decide whether to get the dozens of available integrated SPDs like the Siemens or others. As always thanks you so much Tom.

or to rephrase the above in more US friendly language.. if you Americans use your phase to phase of 240 volts and use 240v to 120 volts transformers.. can your integrated SPD like the Siemens able to connect Phase to Neutral to your 120v line to line transformered ac system? Remember we have same power system only the usage is regulated (we can't use 120v to avoid inflating Trump pockets) so the answer to that applies exactly to my application. In the case of the Siemens, if you short ground to neutral so the alarm won't go off.. I wonder if this can work too in this transformered setup (your "connect the SPD ground wire to the same place the SPD neutral wire is connected" stuff for the normal case). If yes, I'd order two pieces of Siemens.. one to use at breaker entrance to add to existing and the 2nd as type 3 (because I can't find stand-alone US made SPDs like the Prosurge at amazon).

 

[jim mcnamara]

This thread is dragging on a bit. I'll try to help: let's move it to electrical engineering, which is really what 90% of the discussion is about. @jim hardy has discussed this before I think.

 

[Tom.G]

Googling has led me to electrical engineering section in stack exchange.. I think the details of the above is because if the wires are not 10 meters.. there is not enough inductance to limit the current. Not only this. But the clamping won't work well without the impedance in the wires. So I guess it has double purpose. I guess this answers my own questions in the message prior to this. I'll grill the electrical engineers there if I have more detail questions about the technical aspects of it.

Good! It sounds like you learned a bunch there. I started an rudimentary explanation last night... then the Internet went down in the neighborhood! Something about the Internet provider having a power outage. But you probably got a lot more background information on your stack exchange journey.

About the transformer. You may make sense about lowering down 220 volts to 110 volts to get lower clamping voltage. I wonder if all those countries with 220 volts also use 110 step down transformer to get lower clamping voltage? Well. I have difficulty finding plug in SPDs made in USA (I don't want made in china anymore). Most are integrated. So I wonder what would happen if I used transformer and get 110 volts line to line.. Would the dozens of intergrated SPDs made in US able to distinguish between whether the 110 volts came from line to neutral (in the US power system) or came from line to line (in my country)?

If you use a 240/120V transformer and an added physical Ground as in post #126 and repeated below, the US type 3 plug-in SPDs will see exactly what they need and will work fine. It will likely be difficult to find any that are actually made in the US though.

Remember we have same power system only the usage is regulated (we can't use 120v to avoid inflating Trump pockets) so the answer to that applies exactly to my application.

I disagree. If you had the same or even equivalent system, this discussion would have concluded many pages ago.

The difference is:

• The US has a Ground-referenced electrical system with an additional electrical Ground 'Safety Ground' at each outlet.
• Yours is NOT Ground referenced (as indicated by you getting a shock from the Neutral wire) and has NO 'Safety Ground'. (Green wire)

These differences make it difficult/impossible to get both maximum surge protection AND maximum protection to Humans and nearby equipment.

The Siemens FS140 seems a very good choice for a Ground referenced system with a Safety Ground. You can approach that maximum protection for your system by using a 240/120V transformer, adding a physical Ground connection as described in post #126, connecting one transformer secondary lead to the physical Ground connection, and using a Siemens FS140 SPD at the load with its ground wire connected your physical Ground as described in post #126. Anything less is wishful thinking and hoping 'It's good enough'. Nothing is perfect, even with unlimited time and funds, I'm trying to come up with 'best practices' solutions that fit in your constraints.

Now that this thread is in the Elecrical Engineering section maybe others can come up with better solutions.
(But of course by biased opinion is 'it's pretty darn good so far.' )

I think many of us learned a whole bunch of stuff throughout this project. I sure did!

Cheers,
Tom

 

[kiki_danc]

Good! It sounds like you learned a bunch there. I started an rudimentary explanation last night... then the Internet went down in the neighborhood! Something about the Internet provider having a power outage. But you probably got a lot more background information on your stack exchange journey.
If you use a 240/120V transformer and an added physical Ground as in post #126 and repeated below, the US type 3 plug-in SPDs will see exactly what they need and will work fine. It will likely be difficult to find any that are actually made in the US though.I disagree. If you had the same or even equivalent system, this discussion would have concluded many pages ago.

The difference is:

• The US has a Ground-referenced electrical system with an additional electrical Ground 'Safety Ground' at each outlet.
• Yours is NOT Ground referenced (as indicated by you getting a shock from the Neutral wire) and has NO 'Safety Ground'. (Green wire)

These differences make it difficult/impossible to get both maximum surge protection AND maximum protection to Humans and nearby equipment.

The Siemens FS140 seems a very good choice for a Ground referenced system with a Safety Ground. You can approach that maximum protection for your system by using a 240/120V transformer, adding a physical Ground connection as described in post #126, connecting one transformer secondary lead to the physical Ground connection, and using a Siemens FS140 SPD at the load with its ground wire connected your physical Ground as described in post #126. Anything less is wishful thinking and hoping 'It's good enough'. Nothing is perfect, even with unlimited time and funds, I'm trying to come up with 'best practices' solutions that fit in your constraints.

Ok. But what I was asking was the following. The line to neutral lead in the Siemens FS140 was supposed to be connected to your US based phase and neutral of 120 volts. But in my case. I will put a 220v-110v transformer in my phase to phase of 240 volts turning them 120 volts. So my 120 volts now would be line to line (or phase to phase in your US language). Now I'm asking if I can connect the Siemens FS140 line to neutral leads to these 120 volts line to line output from transformer? Remember the line to line leads in Seimens FS140 was supposed to be connected to each of your 120 volts phase to create 240 volts.. but my secondary transformer line to line is now 60 volts to 60 volts so I can't use the line to line leads in the Siemens but phase to line which was supposed to be connected to your US phase to line of 120 volts... Remember the MOV inside the Siemens is 150Vac phase to neutral.. and 300Vac if two in series.. their line to line leads automatically has 300Vac MOVs and you can't use this for 120v output because the clamping voltage would be too high or mismatched... hope you get this subtle difference..

Now that this thread is in the Elecrical Engineering section maybe others can come up with better solutions.
(But of course by biased opinion is 'it's pretty darn good so far.' )

I think many of us learned a whole bunch of stuff throughout this project. I sure did!

Cheers,
Tom

 

[jim hardy]

I've not yet digested the seven pages.

Lookimg fpr a sketch someplace of how OP's system is earthed , if at all .. And the manual for that surge suppressor.

 

[kiki_danc]

Ok. But what I was asking was the following. The line to neutral lead in the Siemens FS140 was supposed to be connected to your US based phase and neutral of 120 volts. But in my case. I will put a 220v-110v transformer in my phase to phase of 240 volts turning them 120 volts. So my 120 volts now would be line to line (or phase to phase in your US language). Now I'm asking if I can connect the Siemens FS140 line to neutral leads to these 120 volts line to line output from transformer? Remember the line to line leads in Seimens FS140 was supposed to be connected to each of your 120 volts phase to create 240 volts.. but my secondary transformer line to line is now 60 volts to 60 volts so I can't use the line to line leads in the Siemens but phase to line which was supposed to be connected to your US phase to line of 120 volts... Remember the MOV inside the Siemens is 150Vac phase to neutral.. and 300Vac if two in series.. their line to line leads automatically has 300Vac MOVs and you can't use this for 120v output because the clamping voltage would be too high or mismatched... hope you get this subtle difference..

If my description was vague since I'm not a native.. here's an illustration:

You are to connect the line 1 and line 2 leads of the Siemens to each of the 120 Vac power wire making up 240volts... but what if you put 220v-110v step down transformer in phase to phase ac supply wires turning it into 110 volts.. then you can't no longer use the same line 1 and line 2 leads in the transformer output of 120 volts because the MOV in series is rated at 300Vac.. you are supposed to connect now the Line 1 and neutral to the 120v output of the transformer (that has phase to phase input) right?

 

[Tom.G]

Now I'm asking if I can connect the Siemens FS140 line to neutral leads to these 120 volts line to line output from transformer? Remember the line to line leads in Seimens FS140 was supposed to be connected to each of your 120 volts phase to create 240 volts..

Yes. Connect the Neutral lead of the FS140 to the wire that goes to the Grounded secondary terminal of the transformer. The Line leads of the FS140 get connected together then to the wire that goes to the other transformer terminal. And of course the FS140 Ground wire goes to your newly installed Safety Ground.

Lookimg fpr a sketch someplace of how OP's system is earthed , if at all .. And the manual for that surge suppressor.

@jim hardy
There was only one sketch shown that indicated IF there was a Neutral (Center Tap) on a 240V line then that would be Grounded. The OPs experience relating to getting a shock when contacting the 'Neutral' and a concrete wall indicates no Ground reference of incoming power.

the manuals were found with: https://www.google.com/search?&q=siemens+fs140+manual
They are: https://w3.usa.siemens.com/us/internet-dms/btlv/PowerDistributionComm/PowerDistribution/docs_EABU%20docs/TPS3_09.pdf
https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43430
https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43434

Cheers,
Tom

 

[kiki_danc]

Yes. Connect the Neutral lead of the FS140 to the wire that goes to the Grounded secondary terminal of the transformer. The Line leads of the FS140 get connected together then to the wire that goes to the other transformer terminal. And of course the FS140 Ground wire goes to your newly installed Safety Ground.

If you connect line 1 and line 2 of the Siemens to the 2 output of the transformer.. then the MCOV would still be 300Vac.. it's too high for 120 volts output... to force it to use the 150Vac MCOV MOV... the line 1 and neutral must be connected to the output of the transformer.. why can't this be done? This is to make sure you only have 150Vac MCOV used...

@jim hardy
There was only one sketch shown that indicated IF there was a Neutral (Center Tap) on a 240V line then that would be Grounded. The OPs experience relating to getting a shock when contacting the 'Neutral' and a concrete wall indicates no Ground reference of incoming power.

the manuals were found with: https://www.google.com/search?&q=siemens+fs140+manual
They are: https://w3.usa.siemens.com/us/internet-dms/btlv/PowerDistributionComm/PowerDistribution/docs_EABU%20docs/TPS3_09.pdf
https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43430
https://www.downloads.siemens.com/d...aspx?pos=download&fct=getasset&id1=BTLV_43434

Cheers,
Tom

 

[Tom.G]

The FS140 is a type 2 SPD, it doesn't clamp the voltages as low as a type 3 because it is rated at a higher current. Note the rated voltage L-N (MCOV) is 150V, for a 120V supply. Your 24VDC supply is rated for 300V for a 5 sec. surge.
I thought this was a temporary installation of the FS140 at the protected equipment while you were finding a type 3 you were happy with. It's still better than nothing until you get a type 3.

 

[kiki_danc]

The FS140 is a type 2 SPD, it doesn't clamp the voltages as low as a type 3 because it is rated at a higher current. Note the rated voltage L-N (MCOV) is 150V, for a 120V supply. Your 24VDC supply is rated for 300V for a 5 sec. surge.
I thought this was a temporary installation of the FS140 at the protected equipment while you were finding a type 3 you were happy with. It's still better than nothing until you get a type 3.

No. Transformer setup is supposed to be a permanent solution because clamping voltage of type 3 is same as type 2.. the lower figure of strip surge protector you saw at amazon is because it uses UL 1449 second edition test vector which uses 6000 volts and 500 ampere only while UL 1449 third edition use 3000 ampere... but if all will use same third edition, result is the same... clamping voltage is dependent on MCOV only and not the surge current rating.. the following is example of a type 3 that uses third edition test vector and it still has 1100 volts clamping voltage.

http://www.tslpro.com/en/ka-type--surge-arrestor-58.html

 

[kiki_danc]

No. Transformer setup is supposed to be a permanent solution because clamping voltage of type 3 is same as type 2.. the lower figure of strip surge protector you saw at amazon is because it uses UL 1449 second edition test vector which uses 6000 volts and 500 ampere only while UL 1449 third edition use 3000 ampere... but if all will use same third edition, result is the same... clamping voltage is dependent on MCOV only and not the surge current rating.. the following is example of a type 3 that uses third edition test vector and it still has 1100 volts clamping voltage.

http://www.tslpro.com/en/ka-type--surge-arrestor-58.html

View attachment 231683

I knew since 5 days ago that clamping voltage is dependent on MCOV only and not related to surge current rating. this was the reason why we discussed all these transformers options because it's supposed to be permanent.. the simplest would be to get the following 150Vac module and connect it to my transformer 110v output...

But I want to try other US brand (prosurge is made in china).. this was why I was asking how do you connect the Siemens to the transformer t to make use of the one 150Vac MOV only. if you will connect the line 1 and line 2 to the transformer output of 120 volts.. you will still have MCOV of 300Vac inside the Siemens.. any idea? Because if not possible then I have no choice but to get the above..

Of course if type 3 with lower surge current indeed have lower clamping voltage.. then of course i'll get a type 3...

 

[kiki_danc]

Can anyone prove that clamping voltage is related to surge current rating? I think it's primarily connected to MCOV only.. the following is a background brief about it from a GE SPD page:

http://apps.geindustrial.com/publibrary/checkout/DEQ-155?TNR=FAQs|DEQ-155|PDF&filename=DEQ-155 - SPD FAQs.pdf

"What are some of the pitfalls when comparing clamping
voltage ratings between SPD manufacturers?

A: The task of comparing clamping (let-thru) voltage ratings
between SPD manufacturers’ published data, may initially
be perceived as a routine process. However, clamping
voltage can be one of the more ambiguous of all SPD
ratings. In simplifi ed terms, SPD clamping voltage can be
defi ned as the peak let-through voltage the SPD will allow
for a given surge test wave. Most SPD manufacturers will
publish average clamping performance data for their
various design types, and almost all will publish this data
while referencing one or more of the surge test waves
that are defi ned in IEEE Standard C62.41. While the reference
to C62.41 is valid, it sometimes leads customers
and specifi ers to believe that IEEE 62.41 is a standard that
provides a defi nitive testing methodology for the purpose
of determining SPD performance ratings. Unfortunately,
this is not the case, as IEEE C62.41 only defi nes the
surge environment and suggested test waveforms for
the various surge risk locations. The absence of a uniform,
industry accepted test plan leads to a variety of testing
methods that can be as unique as the manufacturers
themselves. For instance, some manufacturers may
measure the clamping voltage directly at the connecting
terminals of the SPD, whereas others might measure
with 6” or even longer leads. Others may omit critical
components such as an integral disconnect or fusing.
Any one of these practices can dramatically affect test
results. When comparing clamping voltage data, it is
always a good idea to request certified reports that
describe the construction of the test samples and detailed
testing methodologies. This will provide a better understanding
of expected performance when comparing
SPD types."

Tom, what do you think? I was thinking of using the Line 1 and Neutral lead of the Siemens to connect to the transformer 120v output to make use of the 150Vac.. but I forgot the Line 2. If it would not be connected then the unit would keep alarming.. so I guess this option may not work. Is there no way to trick the unit into using Line 1 and neutral leads only?

But if I can find technical literature and proof that clamping voltage is dependent on surge current rating, then surely I'd just get the 5kV type 3 only but then transformer from 220v to 110v is still required isn't it?

Does this mean for those countries with 220volts.. they always use 110v step down transformers in the equipment to get lower clamping voltage?

 

[kiki_danc]

Tom and other EE. I have spent 1.5 hours googling for the reference that VPR is controlled by surge current rating but can't seem to find it.. for example the following are bonafide type 3 device:

https://www.leviton.com/en/docs/Q-655G_Surge_Protective_Devices_BR.pdf

You will notice that the VPR are all the same.. Notice the 36kA has even higher VPR of 700V compared to the 84kA 600V. This when pulsed with a surge of 6000Volts and 3000 ampere UL 1449 third edition test vector..

So I'll wait for your comment first about theoretical arguments why VPR may still be related to surge current capacity rating. Maybe if the pulse is only 2000 volts and 300 ampere, the clamping voltage of lower current surge capacity will be lowered? Is there proof for this?

This is the most important variable before I decide whether to get a low surge capacity type 3 or moderate surge capacity type 2 to be put at equipment. The reason I prefer type 2 at equipment is because only quality brands have type 2 SPD and thoroughly tested while most type 3 amazon power strips are not quality tested well enough.

 

[jim hardy]

So I'll wait for your comment first about theoretical arguments why VPR may still be related to surge current capacity rating. Maybe if the pulse is only 2000 volts and 300 ampere, the clamping voltage of lower current surge capacity will be lowered? Is there proof for this?

Surge testing in my day was done using a source with specific impedance that delivered a decaying sinewave voltage surge
about 1973 it was simply called IEEE SWC ---- probably it's what became ANSI C37.90 ?
anyow the surge voltage could force a calculable current through that impedance
so perhaps my basic understanding of the question at hand is warped by old prejudices.
Volts is Joules per Coulomb
so
to get from a Volt rating to the Joule rating of a suppressor
one would have to multiply Volts by Coulombs and he'd wind up with Volt-Amp-Seconds = Joules.

Amps will likely be not straightforward to calculate

Trying to relate a voltage rating to current i think would require some knowledge of the source impedance assumed, and I'm as yet unfamiliar with the present day standards and how they were derived.

I do know the 1970-ish IEEE SWC of my day came about when solid state first made its way into switchyard protective relaying.
As you can imagine, interrupting kiloamps makes large di/dt transients hence significant dΦ/dt transients,
and those dΦ/dt 's induce amazing transient voltages in the wires that interconnect protective relaying.
But since they're coupled through air the 'source impedance' is considerable.
So IEEE actually went out to some switchyards, measured some transients,
and came up with a "IEEE SWC Test Generator" that produced similar voltage and current waves typical of those they'd captured ..
Here's a description from my day

Control Technology International, Inc.
15468 East Hinsdale Circle
Centennial, Colorado 80112-4225 USA
Phone: (303)-400-0547 Fax: (303)-400-0571 Toll Free: 1-888-CTII-USA
WorldWideWeb: www.ctii-usa.com Email: ctii@ctii-usa.com

The Oscillatory and Fast Transient (SWC) Test Specifications2.2 Oscillatory (SWC) Test Wave Shape and Characteristics. The oscillatory SWC test wave is an oscillatory wave, frequency range of 1.0 MHz to 1.5 MHz, voltage range of 2.5kV to 3kV crest value of first peak, envelope decaying to 50% of the crest value of first peak in not less than 6 ms from the start of the wave. The source impedance shall be from 150 to 200W. The test wave is to be applied to a test specimen at a repetition rate of not less that 50 tests per second for a period of not less than 2.0 seconds. (All voltage and time values refer to the open circuit condition of the generator.)2.3 Fast Transient (SWC) Test Wave Shape and Characteristics. The fast transient SWC test wave is a unidirectional wave. Its rise time, from 10 to 90 % shall be 10 ns maximum. The crest duration above 90% shall be at least 50 ns. The decay time, from crest to 50% of crest value, shall be 150 ns +/- 50 ns. The crest voltage is between 4kV and 5kV, open circuit. The source impedance during the initial rise time is 80 ohms or less. The test wave is applied for not less than 2 seconds at a repetition rate of not less than 50 pulses per second. Pulses of both polarities are to be applied. (All voltage and time values refer to the open circuit condition of the generator

That's just me refreshing the old gray cells . I still have pages of your thread to digest.
Meantime i found and saved this presentation to get myself more current(no pun intended) on the subject
file:///C:/Users/Owner/Downloads/IEEE%20Surge%20Protection%20Presentation.pdf

EDIT SOURCE - beware, this stupid IEEE link doesn't open a page , it directly downloads the presentation to your C drive without asking !

perhaps some of you IEEE members can access the standards it references.
and tell IEEE for me
"Gentlemen do not write on other gentlemen's computers without permission!"

So while i know this post hasn't really contributed to the thread , and i apologize for that

thanks for tolerating an old guy trying to get himsellf up to where he can help. I've jotted down the links here for my own reference but if they help anybody else I'm overjoyed.

Been a lot of progress in the last fifty years, i'd say. I have miles to go before i speak on this topic...

http://apps.geindustrial.com/publibrary/checkout/DEQ-155?TNR=FAQs|DEQ-155|PDF&filename=DEQ-155 - SPD FAQs.pdf

emphasis mine - jh
Q: What are some of the pitfalls when comparing clamping voltage ratings between SPD manufacturers?
A: The task of comparing clamping (let-thru) voltage ratings between SPD manufacturers’ published data, may initially be perceived as a routine process.
However, clamping voltage can be one of the more ambiguous of all SPD ratings.
In simplified terms, SPD clamping voltage can be defined as the peak let-through voltage the SPD will allow for a given surge test wave.
Most SPD manufacturers will publish average clamping performance data for their various design types, and almost all will publish this data while referencing one or more of the surge test waves that are defined in IEEE Standard C62.41

What I'm taking away from this is the science of surge protection is still largely empirical.

 

[Tom.G]

Yes. Connect the Neutral lead of the FS140 to the wire that goes to the Grounded secondary terminal of the transformer. The Line leads of the FS140 get connected together then to the wire that goes to the other transformer terminal. And of course the FS140 Ground wire goes to your newly installed Safety Ground.

If you connect line 1 and line 2 of the Siemens to the 2 output of the transformer.. then the MCOV would still be 300Vac.. it's too high for 120 volts output... to force it to use the 150Vac MCOV MOV... the line 1 and neutral must be connected to the output of the transformer.. why can't this be done? This is to make sure you only have 150Vac MCOV used...

this was why I was asking how do you connect the Siemens to the transformer t to make use of the one 150Vac MOV only. if you will connect the line 1 and line 2 to the transformer output of 120 volts..

Read the bolded parts above. They all say the same thing.

Of course if type 3 with lower surge current indeed have lower clamping voltage.. then of course i'll get a type 3

Read the specs for the type 2 and the type 3 and compare the clamping voltages at the same currents, then make your decision.

Cheers,
Tom

 

[kiki_danc]

Read the bolded parts above. They all say the same thing.

Yesterday I was analyzing this sentence of your for half an hour "Yes. Connect the Neutral lead of the FS140 to the wire that goes to the Grounded secondary terminal of the transformer. The Line leads of the FS140 get connected together then to the wire that goes to the other transformer terminal."

So let me take this opportunity to clarify. When you said "The Line leads of the FS140 get connected together".. did you mean Line 1 and Line 2 are shorted together and connected to one lead of the secondary.. while the other lead is connected to neutral (and the center lead to ground)? But won't the Siemens sound fault alarm if line 1 and line 2 are shorted??

Read the specs for the type 2 and the type 3 and compare the clamping voltages at the same currents, then make your decision.

Cheers,
Tom

Clamping voltage seems to be the same for type 2 and type 3 given the same pulse of 6000V and 3000Ampere. I'm looking for a theoretical justification. Anyway I think the best power strip in amazon is this:

https://www.amazon.com/gp/product/B0009K66KY/?tag=pfamazon01-20

The spec is in the message earlier. It passed UL third edition test. So if the Siemens would detect fault if line 1 and line 2 is shorted like you asked, then I guess the solution would be this power strip to make use of the line to neutral MOV... the strip won't sound alarm. This is because I can't find individual MOV module like prosurge which is made in china.

 

[kiki_danc]

Yesterday I was analyzing this sentence of your for half an hour "Yes. Connect the Neutral lead of the FS140 to the wire that goes to the Grounded secondary terminal of the transformer. The Line leads of the FS140 get connected together then to the wire that goes to the other transformer terminal."

So let me take this opportunity to clarify. When you said "The Line leads of the FS140 get connected together".. did you mean Line 1 and Line 2 are shorted together and connected to one lead of the secondary.. while the other lead is connected to neutral (and the center lead to ground)? But won't the Siemens sound fault alarm if line 1 and line 2 are shorted??

Let me illustrate the above with the following image:

Maybe you meant connecting L1 and L2 of the Siemens to L1 and L2 of the transformer secondary and connecting the neutral to the center tap??

But then the MOV that would be engaged in the Siemens would be two 150Vac Mov making up 300Vac... so using it for 120 volts would produce too high clamping voltage.. I was asking if you could connect the L1 of the Siemens to the L1 of the transformer secondary and neutral of the Siemens to L1 of the transformer secondary?? That way you can engage only one 150Vac MOV of the siemens L-N connection.

Clamping voltage seems to be the same for type 2 and type 3 given the same pulse of 6000V and 3000Ampere. I'm looking for a theoretical justification. Anyway I think the best power strip in amazon is this:

https://www.amazon.com/gp/product/B0009K66KY/?tag=pfamazon01-20

The spec is in the message earlier. It passed UL third edition test. So if the Siemens would detect fault if line 1 and line 2 is shorted like you asked, then I guess the solution would be this power strip to make use of the line to neutral MOV... the strip won't sound alarm. This is because I can't find individual MOV module like prosurge which is made in china.

 

[kiki_danc]

Tom. Since you only surf a few moments in the evening.. let me ask this now so I can decide whether to get this:

If you really meant connecting L1 and L2 of the Siemens to L1 and L2 of the transformer secondary and connecting the neutral to the center tap (right?) as detailed in the message prior to this. Then there is this problem of using total of 150Vac+150Vac MOV since L1 to L2 in the siemens is 300Vac. I only want to use 150Vac MOV across L1 and L2 of the 220v to 110v step down transformer. Would the following work?

That is. The L(ine) of the Leviton power strip would be connected to L1 of the transformer secondary and the N(eutral) of the Leviton power strip would be connect to L2 of the transformer secondary (while the ground is either left hanging or connected to future ground line).. would this work?? Can this trick the L-N of the Leviton power strip to connect to L1 and L2 of the transformer secondary to limit it to 150Vac MOV across the 120 volts secondary transformer output? If yes. Then I'd buy this since the Siemens split phase circuit may not be tricked. Thank you.

 

[Tom.G]

did you mean Line 1 and Line 2 are shorted together and connected to one lead of the secondary.. while the other lead is connected to neutral

Yes.

(and the center lead to ground)?

What center lead?

But won't the Siemens sound fault alarm if line 1 and line 2 are shorted??

Unlikely from the product description

Regarding the Leviton 5100-PS you found at Amazon:
If you are comfortable with the 600V VPR its as good as any. If you are interested in 330V VPR look at the TSFA6A120V here: https://www.erico.com/part.asp?part=TSF6A120V
One reference I ran across (can't find it now) is the lowest UL rating is 330V, then in goes up 400, 500, 600...

Tom. Since you only surf a few moments in the evening..

Not quite so, more like 4+ hours; most of it lately looking up data for, or explaining to, you!

More to follow...

 

[kiki_danc]

Yes.What center lead?

.

The black wire in the center... but then if you short the L1&L2 of the Siemens leads and connect it to one of the blue leads.. then what do you connect to the 2nd blue lead? This was what I was trying to figure out yesterday for an hour.

Unlikely from the product description

Regarding the Leviton 5100-PS you found at Amazon:
If you are comfortable with the 600V VPR its as good as any. If you are interested in 330V VPR look at the TSFA6A120V here: https://www.erico.com/part.asp?part=TSF6A120V
One reference I ran across (can't find it now) is the lowest UL rating is 330V, then in goes up 400, 500, 600...

Oh.. I'd get the erico then.

Not quite so, more like 4+ hours; most of it lately looking up data for, or explaining to, you!

More to follow...

Thanks so much.

 

[jim hardy]

Edited source for that informative IEEE Surge presentation in post 143 , see cautionary note