Arc Suppression for Fuji PXR4 Micro Controller

In summary, the Fuji PXR4 Micro Controller is triggering the DPST relay which is experiencing arcing with also some bouncing. A SSR (Solid State Relay) may be a better option to swap out for because the problem will be solved.
  • #1
Gordo
12
1
DPST Power relay has 120VAC coil & 40A contacts (resistive) ratings. A Fuji PXR4 Micro Controller is triggering the relay; the load is a 220V pottery kiln element. The contacts are arcing (but not bouncing) at make & break on nearly every cycle. The above relay just replaced a previous SPST relay which experienced the same arcing with also some bouncing - which eventually pitted the contacts.

Is there something to be added to reduce/eliminate the arcing?

Thanks,
Gordo
 
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  • #3
davenn said:
Hi Gordo
welcome to PF :)

I suggest you swap it out for a SSR ( Solid State Relay). Problem will be solved :smile:

https://www.google.com.au/?gws_rd=ssl#q=solid+state+relay

Dave
Thanks Dave, but my Fuji controller won't talk to SSR's. A fuji model that will, costs ~ $200. That's a "swapmeet" I can't afford to go to! :-(
Gordo
 
  • #4
Gordo said:
Thanks Dave, but my Fuji controller won't talk to SSR's. A fuji model that will, costs ~ $200. That's a "swapmeet" I can't afford to go to! :-(
Gordo

what is the type/style/voltage etc output of the controller ?
 
  • #5
Gordo, What exactly do you mean by pitting the contacts?
 
  • #6
davenn said:
what is the type/style/voltage etc output of the controller ?
Fuji Micro Controller #PXR4-RAY1-4VoA1 : Power: 100 - 240VAC Measured Value Input: Thermocouple (Type "K" ) Control Output: Relay
Fuji Micro Controller #PXR4-RCY " * * : Solid State Relay
the "C" in the 6th digit position indicates Solid State Relay in the "Control Output".

I've been in touch with Fuji on this: Thinking that all the model's features are "setable" like the dozens of other options. This feature is fixed...therefore the "A" or "C" (in the 6th digit position of the controller number) must be selected at time of order. I purchased this Model "A" in 2/2/2007. SSR (model "C") was a lesser deal then, therefore much more expensive then.

I just have to believe that there is a simple combo of capacitor, resister, diode, gizmo, whatever, that will moderate the shock (eliminate the arcing) of the make-break load on the DPST relay.

Thanks for your interest,
Gordo
 
  • #7
likephysics said:
Gordo, What exactly do you mean by pitting the contacts?
contacts that are burnt - pitted, eventually to "weld".
 
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  • #8
  • #9
Is the pottery kiln have an inductive element?
As you mentioned you could try using a RCD or just a RC snubber.

Why can't the Fujitsu Micro drive SSDs.
There are SSDs available down from 3.3VDC to 220VAC
 
  • #10
You may need a two-stage relay. Use the existing relay to trigger a second relay with a higher current interrupting rating.

But first discard and replace the relay with pitted contacts.
 
  • #11
davenn said:
I meant to ask ... reading back I don't see
I assume the 220V to the kiln is AC ?have a look here and see if any ideas there may help ...
http://www.industrologic.com/mechrela.htm
Yes, AC. Looks like the industrologic link will help with adding R &C contact protection. Thanks for the help. This forum is really sharp.
 
  • #12
anorlunda said:
You may need a two-stage relay. Use the existing relay to trigger a second relay with a higher current interrupting rating.

But first discard and replace the relay with pitted contacts.
Thanks for the ideas. I'll try adding the R & C "protection" - first.

Replacement = done. See my #1 post.
 
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  • #13
likephysics said:
Is the pottery kiln have an inductive element?
As you mentioned you could try using a RCD or just a RC snubber.

Why can't the Fujitsu Micro drive SSDs.
There are SSDs available down from 3.3VDC to 220VAC
Thanks for the notes.
It's resistive. My impression: "less than industrial sized", and perhaps all pottery kilns are resistive...like oversized toasters. I've use mine to warm bagels.
Yes, Fuji Electric Systems Company makes controllers that drive SSR's. See my #3 & #6 posts.
I appreciate all the help. I'll use it now to do my homework.
G.
 
  • #14
Big loads just make lots of sparks.

40 amp rated contacts should last for thousands of cycles, unless that kiln is huge. You didn't say what is its current draw.

220 volts at 40 amps is 8.8kw

http://www.te.com/content/dam/te/global/english/products/relays/catalogs/files/powerrelaysbook/c0-v4bg-4.pdf [Broken]
 
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  • #15
After looking at the specs for the -ray1 and the -rcy1 the only difference is that the ray1 has contact output control (you supply power to the contacts) and the rcy1 supplies 24vdc output for a solid state relay.

If you purchase a solid state relay with a 90-280 vac control and rated for 40+ amps (sorry if I did not see your load current in any above posts) it should just replace your contactor directly. I believe this will work, http://www.crydom.com/en/Tools/parametric-search.shtml?type=panel. If not just input your parameters and it will give you a part number. I've used crydoms for years with excellent results.
 
  • #16
wirenut said:
After looking at the specs for the -ray1 and the -rcy1 the only difference is that the ray1 has contact output control (you supply power to the contacts) and the rcy1 supplies 24vdc output for a solid state relay.

If you purchase a solid state relay with a 90-280 vac control and rated for 40+ amps (sorry if I did not see your load current in any above posts) it should just replace your contactor directly. I believe this will work, http://www.crydom.com/en/Tools/parametric-search.shtml?type=panel. If not just input your parameters and it will give you a part number. I've used crydoms for years with excellent results.

I'll reply to Jim & Wirenut here. I really appreciate the interest/help from everyone on this thread. First, I'm confused...I'm hardly up to speed on this technology.

The kiln is 220VAC 20A - 4.4kw Yes, my Fuji PXR4-RAY1 ...the control output supplies only a signal to the 120VAC coil of my Grainger Magnacraft #6CUR4 (DPDT 40A Resistive. Fuji tech has advised that to run a solid state relay I need their RCY1 Controller. BTW, on the back of both units, taps #5 & #6 - RAY1 connects to the coil of the mechanical relay (Grainger) & RCY1 connects to a 24VAC or DC SSR .

I'm confused. Wirenut, do I understand that there is a SSR that accepts a 100-240VAC output signal from my RAY1 (it contains a relay - the RCY1 does not) & hence switches a 220VAC 20A line load (every 2 minutes for 11 hours - the contacts remain closed aprox 15 sec. each 2 min)? I'll check the crydom.com link; perhaps that will help me understand equip ability/availability.

Thanks, Gordo
 
  • #17
Gordo said:
switches a 220VAC 20A line load (every 2 minutes for 11 hours - the contacts remain closed aprox 15 sec. each 2 min)
No wonder it eats relays!
 
  • #18
As long as you between 90vac and 280vac the part I gave you will work.
All this solid state relay is is a mechanical relay without moving contacts, but electronic components
to control the current flow through the output.
The only thing I think I forgot to say is for the 220volt output you should use 2 (one for each line), and just put the control
power to each of them in parallel.
 
  • #19
After looking through the Grainger catalog these parts should work (remember you will need 1 for each line) 1DTG8 OR 1DTG3 , the only difference
being one has a minimum output voltage of 24v and the other is 48v. Your output voltage is 220v.
 
  • #20
Gordo said:
Is there something to be added to reduce/eliminate the arcing?
Nothing good snubbering can't deal with.
In high power applications, even without dominant inductive loads, snubber circuit is necessary to protect switch/relay from HV surges/excessive arcing during switching actions. It is strange to me if the relay you have is sold without snubber circuit. If it comes with snubber and arcing is still significant, than the relay is inadequte for the load. In the case of high inductive loads (like motors) I would always prefer snubber circuit be put in parallel to the load rather than parallel to the relay contacts. In your case this needs to be analyzed.
 
  • #21
Gordo:

Per catalog that's a high quality contactor with silver alloy contacts.
If the sparking really bothers you,
Wirenut is on the right track with SSR's.

And you're right, your controller part # decodes to only a relay contact output.
So you'll have to trigger an SSR with something that your controller can switch, as anorlunda suggested.

So called "Wall Warts" are plentiful in thrift stores in low voltage AC and DC styles.
One of those would give you low voltage to switch into a SSR like Crydom A2450.

SSR's aren't real cheap. "zero switching", which you don't need for resistive load, might add to the cost .
That Crydom A2450 is about fifty bucks.
And it ought to be mounted with a heatsink.
http://www.crydom.com/en/Products/Catalog/s_1.pdf
You'd pick a wall-wart having output compatible with SSR's input and switch it through your controller.
Pick a "Normally Open" relay so it'll turn kiln off when controller is off.

Your controller appears to have a robust enough internal relayAnother thought is to turn off part of the heating element during temperature hold so as to reduce the current.
If it's on just an eighth of the time (15 sec out of two minutes), then switching out 3/4 of the heating element should give about a minute or two on and ~1.75 minutes off as before but only 5 amps. Maybe there's parallel connected elements you could switch to series.

just thinking out loud.

old jim
 
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  • #22
Most arcing occurs when the circuit is open. An MOV or RC snubber will eat the arc energy, improve relay life, and decrease glitches in the controller. You might try these guys:

http://www.cde.com/resources/catalogs/Q-QRL.pdf

Simply building an RC snubber is a bad idea because the resistor will see high transient currents and if the capacitor fails you could end up with a flaming resistor. Better to purchase either a pre-designed Quench Arc, or an MOV rated for 230VAC and roughly 20mm dia.

In either case, the component should be sealed in a metal box to prevent electrical hazards and fire hazards.

- Mike
 
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  • #23
Mike_In_Plano said:
Simply building an RC snubber is a bad idea because the resistor will see high transient currents and if the capacitor fails you could end up with a flaming resistor.
That's why a built-in fuse can be found in a RC snubber circuit for high power applications. Such snubbers have their own relay as part of monitoring circuit to alarm on blown fuse condition.
 
  • #24
zoki85 said:
That's why a built-in fuse can be found in a RC snubber circuit for high power applications. Such snubbers have their own relay as part of monitoring circuit to alarm on blown fuse condition.

I apologize - didn't see the Page 1 of 2 note, - missed page 2 ...first time on this forum. I again extend a hardy thank you to all! Also, I'm pretty much out of my depth!

More background. The kiln is ~ 7"x9"x9" (69" long element 11ohm) just for wax burn-out @ (1350 F.) for the lost wax casting process of gold x silver jewelry. Prior to adding the Fuji in 2007 I've had to babysit it for the 8 or 11 hr process, starting circa 1975.

From the beginning in '75 I've used Grainger's 5Z538 SPST ($20.) With quite a lot of bounce and less arcing. With the addition of the marvelous Fuji I can sleep through the night and come in and cast in the morning.

Last week I installed a Grainger 6CUR4 DPDT $40. I did some testing - not good. didn't do the 11hr program. Removed the new relay - tested it. Replaced it & rewired the whole circuit. Even being the first time breaking both lines of the 220V, I'm now getting no bounce/chatter BUT much more arcing, on make & break). Figure that. BTW the more accurate estimate is: During the 11 hrs, at many of the 2 minute cycle points, the thermocouple does not call for heat. When it does, the average power-on is between 5 and 10 seconds. Probably suggesting that the element is overdesigned. Since 1975 I've only replaced one element.

Your several ideas, some incl specs, (I've given due diligence) are much appreciated and very interesting - sounding very logical; even in light of the comments by the Fuji Electric tech man to the contrary. Perhaps he also works in their sales department!

Therefore I'd like to first travel the "Contact Protection & Arc Suppression" route using "R" & "C". At the end of the day I'd like to sleep thru the 11 hrs more soundly/safely...made possible in part, if my wallet is only lighter by aprox $20. My searches for a suitable R & C have not been successful - any help would be appreciated.

Now, another apology, for this "more that you ever needed" rambling :-(
Gordo
 
  • #25
If you want to try arc supressors Digikey has some fairly cheap, about $10 each in small quantities.
http://www.digikey.com/product-highlights/us/en/cornell-dubilier-quencharc-caps/744 [Broken]
 
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  • #26
@Gordo Can you tell us more about this "bounce/chatter" ?

How much hysteresis do you have set into your controller? See section 6.1 on page 19 of the manual ,
The copy I'm looking at is http://www.fujielectric.com/products/instruments/library/manual/box/doc/TN1PXRn-E.pdf [Broken]
looks like default value is 1%.
It says
Set the hysteresis to avoid chattering.
I'm wondering whether your "chatter" might be caused by the controller's responding to EMI interference introduced into the thermocouple signal by the act of switching 20 amps nearby...

Your short on-time during hold suggests very little hysteresis.
If you have none (or just 1%), try setting it to 10% and see if the chatter stops. If so, decrease it until you're at the verge of chatter and see whether temperature performance is still satisfactory.

Should you connect RC snubbers across the relay contacts be aware they'll pass a few milliamps through the heating element when relay is open.
So you shouldn't depend on the relay to place the element in a condition safe for touching it .
One should never work downstream of anything automatic anyway, remorseless robots that they are.

One other trick to try...
EMI is dependent on the area enclosed by the loop around which your kiln current flows.
For that reason it is desirable to run the two power conductors together and twist them , a turn every few inches will do.
That minimizes the area enclosed by them.
Do not separate them as would seem natural. Running them separately would make a big fat loop. You want a skinny loop even if it takes more wire.

Minimizing the area enclosed by the power wires will minimize the disturbance introduced into your thermocouple wire.
Also, route the thermocouple wire well away from the power wires and avoid running it parallel to them. Perpendicular is better especially when they're close.

Good luck !

old jim
 
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  • #27
jim hardy said:
@Gordo Can you tell us more about this "bounce/chatter" ?

How much hysteresis do you have set into your controller? See section 6.1 on page 19 of the manual ,
The copy I'm looking at is http://www.fujielectric.com/products/instruments/library/manual/box/doc/TN1PXRn-E.pdf [Broken]
looks like default value is 1%.
It says
I'm wondering whether your "chatter" might be caused by the controller's responding to EMI interference introduced into the thermocouple signal by the act of switching 20 amps nearby...

Your short on-time during hold suggests very little hysteresis.
If you have none (or just 1%), try setting it to 10% and see if the chatter stops. If so, decrease it until you're at the verge of chatter and see whether temperature performance is still satisfactory.

Should you connect RC snubbers across the relay contacts be aware they'll pass a few milliamps through the heating element when relay is open.
So you shouldn't depend on the relay to place the element in a condition safe for touching it .
One should never work downstream of anything automatic anyway, remorseless robots that they are.

One other trick to try...
EMI is dependent on the area enclosed by the loop around which your kiln current flows.
For that reason it is desirable to run the two power conductors together and twist them , a turn every few inches will do.
That minimizes the area enclosed by them.
Do not separate them as would seem natural. Running them separately would make a big fat loop. You want a skinny loop even if it takes more wire.

Minimizing the area enclosed by the power wires will minimize the disturbance introduced into your thermocouple wire.
Also, route the thermocouple wire well away from the power wires and avoid running it parallel to them. Perpendicular is better especially when they're close.

Good luck !

old jim
Wow, I'm getting lots of good ideas and an education on many aspects, incl safety "heads-up" re this equipment. Appreciate all.
Re chatter: See 4th para of my #24 post. Arcing is the issue. Perhaps chatter/bounce is not present now because contacts are new. I'll check hysteresis. Your notes indicate %. settings? The manual shows celcius settings. At any rate I'll try some changes. BTW, my manual (2007) for the PXR4/5/9 units is 82 pages w/64 listings of parameters. Also, a 16"x24" sheet with fine print both sides...looks just like a user manual. Not sure :-( or :-) ?
Thanks, Gordon
 
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  • #28
Gordo said:
Therefore I'd like to first travel the "Contact Protection & Arc Suppression" route using "R" & "C". At the end of the day I'd like to sleep thru the 11 hrs more soundly/safely...made possible in part, if my wallet is only lighter by aprox $20. My searches for a suitable R & C have not been successful - any help would be appreciated.
Althought your load can be classified as a resistive one, be sure that kiln has some inductance, and that there is inductance of wiring leads of the circuit, of the part of the relay circuit etc. Once max values of reactive energy of circuit and the relay switching frequency are known, suggesting RC snubber parameters and corresponding components ratings is the easiest part of job. More difficult part are reliability/longevity/safety considerations of the snubber solution -you want all that. You mention the old relay had nonexistent arcing problems but there was lot of "bounce". The contact bouncing had nothing to do with arc suppression (actually, it can make it worse). This is indicatation either of a different relay construction or some of measures for arc mitigation were employed. OTOH, the new relay experiences arcing issues (you don't mention how much before, and how much after the circuit rewireing). It is quite likely the costumer is expected to take care of these issues by himself for specific applications. I understand you don't want spent too much money on this, but good investment usually pays back through longer period of time.
 
  • #29
likephysics said:
Gordo, What exactly do you mean by pitting the contacts?
Websters: pitting transitive verb - to make pits in. to mark with small scars.
Gordo
 
  • #30
zoki85 said:
Althought your load can be classified as a resistive one, be sure that kiln has some inductance, and that there is inductance of wiring leads of the circuit, of the part of the relay circuit etc. Once max values of reactive energy of circuit and the relay switching frequency are known, suggesting RC snubber parameters and corresponding components ratings is the easiest part of job. More difficult part are reliability/longevity/safety considerations of the snubber solution -you want all that. You mention the old relay had nonexistent arcing problems but there was lot of "bounce". The contact bouncing had nothing to do with arc suppression (actually, it can make it worse). This is indicatation either of a different relay construction or some of measures for arc mitigation were employed. OTOH, the new relay experiences arcing issues (you don't mention how much before, and how much after the circuit rewireing). It is quite likely the costumer is expected to take care of these issues by himself for specific applications. I understand you don't want spent too much money on this, but good investment usually pays back through longer period of time.

The old Grainger relays were 5Z538 SPST 40A & they had bounce and arcing - and considerable degradation. The new 6CUR4 DPDT 40A has had no bounce but arcs on most cycles, more on the break. Today I did a 2 hr test after changing the HYS from 20 degrees C to 10 degrees. & Cycle Time (control output 1) from 60 seconds to 150 seconds. These changes made no change in the number of arcing events or intensity. Still no bounce, but the SV temp overshoot varied from 10 to 25% during most of the two hour test - no surprise there considering the setting changes I had just made; Also, the self-tuning process had not had a chance to adjust the performance. Circuit rewiring last week - no difference.

Considering the advise received here and with further reading of Fuji, & considering the 8 year age of it (even considering its very low mileage) I've decided to use it (w/babysitting) and the new Grainger 6CUR4 relay till the relay contacts wear thin. Then pop for a Fuji PXR4 - RCY1 & a SSR.

In the meantime, If someone would spec parts & wiring diagram of a contact protection & arc suppression - w/a resistor & capacitor. Or an RC Snubber part #, I would really like to try that approach. I do not have the knowledge to do that.

Thanks to all for the suggestions and perspectives on this issue.
Gordo
 

1. What is Arc Suppression for Fuji PXR4 Micro Controller?

Arc suppression for Fuji PXR4 micro controller is a feature that helps to reduce or eliminate electrical arcing, which is a common problem in industrial control systems. It is designed to protect the controller and other equipment from damage caused by electrical arcs.

2. How does Arc Suppression work?

Arc suppression works by detecting the presence of an electrical arc and quickly interrupting the circuit to prevent it from damaging the controller. This is achieved through the use of specialized components and algorithms that can detect and respond to arcs in milliseconds.

3. What are the benefits of using Arc Suppression for Fuji PXR4 Micro Controller?

The main benefit of using arc suppression for Fuji PXR4 micro controller is to protect the controller and other equipment from damage. This can help to reduce downtime and maintenance costs, as well as improve the overall reliability of the control system.

4. Is Arc Suppression necessary for all industrial control systems?

While arc suppression can be beneficial for most industrial control systems, it may not be necessary for all systems. Factors such as the type of equipment being controlled and the environment in which it operates should be considered when determining the need for arc suppression.

5. How can I implement Arc Suppression for my Fuji PXR4 Micro Controller?

Arc suppression for Fuji PXR4 micro controller can be implemented by adding specialized arc suppression components to the control system, or by using a controller that already has arc suppression capabilities built-in. It is important to consult with a qualified engineer or technician to determine the best approach for your specific control system.

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