Solving Motor Braking Circuit Problem in Bowling Industry

[H012]

somewhere in the pink line
in place of that wire from C1-23N to TS-27
or C1-23N to whichever terminal that is on the S relay, 10 or 32
View attachment 103634

Schematic shows a wire between relay S terminals 2, 4 and 5
that could be a convenient place if you can see clearly how they accomplished their wiring,
just be careful , you don't want it on the wrong side of terminal 4 !
if there's a single wire on 5 find its other end, hopefully it's a short jumper to 4&2. ( with a single wire from one of those to C1-22J ) that's how i woulda done it.

even between junction of capacitors and centertap of resistor would be okay

schematics don't look a lot like the physical machine, do they ... Got a cellphone picture of it you could upload ?

old jim

Hell no! It doesn't look close HaHa. Never does. Bet you've seen your share of wiring
Nightmares. Yes I will get a picture not sure if I can fit it all in one picture.

 

[Tom.G]

@H012 When you get a chance, would you tell us the make & model of the old style, open frame, relay that was originally in the circuit? We are still trying to track down some ambiguities/inconsistencies into the root cause(s) of your problem. Thanks.

 

[H012]

@H012 When you get a chance, would you tell us the make & model of the old style, open frame, relay that was originally in the circuit? We are still trying to track down some ambiguities/inconsistencies into the root cause(s) of your problem. Thanks.

I have no idea what the model number they are. I can look on one when I go to work today at 3 pm. These relays are obsolete and I'm phasing them out as OSHA won't allow any open frame design be used unless it's a totally enclosed, which in the case of the chassis on the machine that has the relays is not enclosed. I will send a photo also. I know they are Allen Bradley. Thanks

 

[H012]

I have no idea what the model number they are. I can look on one when I go to work today at 3 pm. These relays are obsolete and I'm phasing them out as OSHA won't allow any open frame design be used unless it's a totally enclosed, which in the case of the chassis on the machine that has the relays is not enclosed. I will send a photo also. I know they are Allen Bradley. Thanks

I am concentrating on the sweep because the sweep starts and stops 3 times unlike the table which starts and stops once. If you would be interested you can go on you tube and search AMF 8270 or 8290 pinspotter I'm sure you can see how it functions.This would be just FYI

 

[H012]

@H012 When you get a chance, would you tell us the make & model of the old style, open frame, relay that was originally in the circuit? We are still trying to track down some ambiguities/inconsistencies into the root cause(s) of your problem. Thanks.

They are Allen Bradley 700-C220X10

 

[H012]

somewhere in the pink line
in place of that wire from C1-23N to TS-27
or C1-23N to whichever terminal that is on the S relay, 10 or 32
View attachment 103634

Schematic shows a wire between relay S terminals 2, 4 and 5
that could be a convenient place if you can see clearly how they accomplished their wiring,
just be careful , you don't want it on the wrong side of terminal 4 !
if there's a single wire on 5 find its other end, hopefully it's a short jumper to 4&2. ( with a single wire from one of those to C1-22J , that's how i woulda done it. )

even between junction of capacitors and centertap of resistor would be okay

schematics don't look a lot like the physical machine, do they ... Got a cellphone picture of it you could upload ?

old jim

OK Jim put 8 ohm resistor in place between cap and resistor. Braking unchanged it's OK
Voltage at C1 24 and return unchanged voltage drop off is still quick when running

 

[jim hardy]

OK Jim put 8 ohm resistor in place between cap and resistor.
Did i draw it in the right place ?Braking unchanged it's OK
That bodes very well , and i must admit to mild surprise bur tremendous relief

Voltage at C1 24 and return unchanged voltage drop off is still quick when running
Okay, take a look we'd expect no change there

During braking, motor's main winding current flows along blue line into new resistor then splits. half going through each capacitor to 115 return.
The half that turns right into CSM2 has a straight shot out other side to 115 return
the half that turns left into CSM1 meanders back through C1-24T then contacts 3-8 of S relay to 115 return.

If i understand the circuit,
Voltage at C1-23N should behave like this
At motor start it will jump up to the 22 VAC/(41DC?) you measured in post #70
(question mark on DC reading is because i think it should be random how much DC you see there, if it's always 41DC i don't understand why _{(but that's not unusual )} )
then it will drop to zero as soon as motor reaches speed causing CS to open
when STOP signal de-energizes relay S
allowing its NC contacts to close
voltage will return to C1-23N , and the amount will be whatever the motor makes as an induction generator. That voltage will fade as energy id drained from the motor's inertia.
The resistor should affect rate of energy drain from motor, but how much ? I don't know(the 3 words men fear most).

That resistor HAD to lower the instantaneous current flow into the capacitors, making life easier for your NC contacts.
Since we don't have a 'scope with transient current capture, and my coil didn't tell us anything, we're flying kinda bindIf you can get a reading at C1-23N during a motor braking cycle, we'll divide that by (8 - j 2.65) and figure the amps during braking. (8 is the new resistor you inserted in the circuit...? )
I'm dying of curiosity how much current flows and for how long
That won't tell us the initial current spike but it gives a clue about the motor's behavior, i never did any such experiments and find this interesting

I would suggest
Write this experiment down and put a note inside the machine for the next guy so he'll know what you did
put in a new relay
Surely you know what is average life of these relay contacts?
After say 2/3 of that life, take that relay out and see if we've slowed contact erosion ?

Svein? Tom.G ? Thoughts ?
Kudos to both of you guys , this just might work ! I thought for sure we'd extend coastdown time and de-synchronize the machine.

Keep our fingers crossed this machine runs okay with the extra braking resistor.

HO12 - do you have a contact at AMF ?
Ask him this question, in your own words..

Dear Sir:
We experience short contact life on the AB relays used in model (whichever) Pinsetter and Sweeper
in particular the NC contacts on these relay models
Allen Bradley 700-C220X10
and its replacement
Allen Bradley 700-CF220J
which are used to brake an induction motor by essentially short circuiting it as an induction generator.
We have reason to believe di/dt on contact closure is higher than expected and erodes contact material during contact bounce on make
so we have three questions:
1. What is maximun di'dt for that relay contact on make?
2. What is published subtransient reactance of the motor ? It bears part number (whatever it is)
3. Does motor manufacturer publish, or would you get from his engineering department , estimates of on subtransient fault current available from the motor and initial rate of current rise (di/dt) ?
4. If our suspicion proves correct, transient current erodes the contacts causing premature failure, can you suggest protection for the relay contacts ? This is an industry wide maintenance headache with these machines.

We have equipped one machine with 8 ohms of resistance in series with the braking current path (insert sketch from this post, above).
Coastdown time seems unaffected and we measure (?) amperes of braking current . We will check the relay for contact erosion after ( how many cycles or months ?)

Please advise,

.......



The higher up their organization you send it the better will be the answer you get. I'd find the VP of marketing for AMF bowling products, start at their website and look for "Investor relations - executive team"

If the owner of your company will co-sign with you it'd help.

Lastly, is there an industry magazine you guys read?
In the power plant we loved "Power"magazine because of one regular feature-
a fictional troubleshooter by the name of "Marmaduke Surfaceblow" solved some sticky engineering problem every month
we enjoyed them because they were taken from real events submitted by readers and the writer painted such colorful characters... We young guys all wanted to be confident and blustery and always right like Marmaduke.
http://www.digplanet.com/wiki/Marmaduke_Surfaceblow

Marmaduke Surfaceblow is a fictional engineer. His globe-girdling engineering adventures written by http://www.digplanet.com/wiki/Stephen_Michael_Elonka first appeared in Power Magazine in 1948.http://www.digplanet.com/wiki/Marmaduke_Surfaceblow#cite_note-1

Marmaduke is a marine engineer with vast knowledge of machinery. He works out of an office over O'Houlihan's Machine Shop in the http://www.digplanet.com/wiki/Hell%27s_Kitchen,_Manhattan area of http://www.digplanet.com/wiki/New_York_City . His imposing 6 ft 4 in stature is described in every story along with his steelbrush moustache and size 16 "canal boat" shoes. Surfaceblow smokes Ringelmann #5 cigarshttp://www.digplanet.com/wiki/Marmaduke_Surfaceblow#cite_note-2 that produce acrid clouds leaving others teary-eyed.

If this works you'll want to get the word out to other maintenance men like yourself, submit an article to your trade magazine, editors love real world submissions from the field.

old jim

PS what's voltage at C1-23N when it brakes ? _______

 

[H012]

View attachment 103679

During braking, motor's main winding current flows along blue line into new resistor then splits. half going through each capacitor to 115 return.
The half that turns right into CSM2 has a straight shot out other side to 115 return
the half that turns left into CSM1 meanders back through C1-24T then contacts 3-8 of S relay to 115 return.

If i understand the circuit,
Voltage at C1-23N should behave like this
At motor start it will jump up to the 22 VAC/(41DC?) you measured in post #70
(question mark on DC reading is because i think it should be random how much DC you see there, if it's always 41DC i don't understand why _{(but that's not unusual )} )
then it will drop to zero as soon as motor reaches speed causing CS to open
when STOP signal de-energizes relay S
allowing its NC contacts to close
voltage will return to C1-23N , and the amount will be whatever the motor makes as an induction generator. That voltage will fade as energy id drained from the motor's inertia.
The resistor should affect rate of energy drain from motor, but how much ? I don't know(the 3 words men fear most).

That resistor HAD to lower the instantaneous current flow into the capacitors, making life easier for your NC contacts.
Since we don't have a 'scope with transient current capture, and my coil didn't tell us anything, we're flying kinda bindIf you can get a reading at C1-23N during a motor braking cycle, we'll divide that by (8 - j 2.65) and figure the amps during braking. (8 is the new resistor you inserted in the circuit...? )
I'm dying of curiosity how much current flows and for how long
That won't tell us the initial current spike but it gives a clue about the motor's behavior, i never did any such experiments and find this interesting

I would suggest
Write this experiment down and put a note inside the machine for the next guy so he'll know what you did
put in a new relay
Surely you know what is average life of these relay contacts?
After say 2/3 of that life, take that relay out and see if we've slowed contact erosion ?

Svein? Tom.G ? Thoughts ?
Kudos to both of you guys , this just might work ! I thought for sure we'd extend coastdown time and de-synchronize the machine.

Keep our fingers crossed this machine runs okay with the extra braking resistor.

HO12 - do you have a contact at AMF ?
Ask him this question, in your own words..

Dear Sir:
We experience short contact life on the AB relays used in model (whichever) Pinsetter and Sweeper
in particular the NC contacts on these relay models
Allen Bradley 700-C220X10
and its replacement
Allen Bradley 700-CF220J
which are used to brake an induction motor by essentially short circuiting it as an induction generator.
We have reason to believe di/dt on contact closure is higher than expected and erodes contact material during contact bounce on make
so we have three questions:
1. What is maximun di'dt for that relay contact on make?
2. What is published subtransient reactance of the motor ? It bears part number (whatever it is)
3. Does motor manufacturer publish, or would you get from his engineering department , estimates of on subtransient fault current available from the motor and initial rate of current rise (di/dt) ?
4. If our suspicion proves correct, transient current erodes the contacts causing premature failure, can you suggest protection for the relay contacts ? This is an industry wide maintenance headache with these machines.

We have equipped one machine with 8 ohms of resistance in series with the braking current path (insert sketch from this post, above).
Coastdown time seems unaffected and we measure (?) amperes of braking current . We will check the relay for contact erosion after ( how many cycles or months ?)

Please advise,

.......
The higher up their organization you send it the better will be the answer you get. I'd find the VP of marketing for AMF bowling products, start at their website and look for "Investor relations - executive team"

If the owner of your company will co-sign with you it'd help.

Lastly, is there an industry magazine you guys read?
In the power plant we loved "Power"magazine because of one regular feature-
a fictional troubleshooter by the name of "Marmaduke Surfaceblow" solved some sticky engineering problem every month
we enjoyed them because they were taken from real events submitted by readers and the writer painted such colorful characters... We young guys all wanted to be confident and blustery and always right like Marmaduke.
http://www.digplanet.com/wiki/Marmaduke_Surfaceblow
If this works you'll want to get the word out to other maintenance men like yourself, submit an article to your trade magazine, editors love real world submissions from the field.

old jim

PS what's voltage at C1-23N when it brakes ? _______

I will check voltage during breaking at c1 23.
I did speak with head of facilities sometime back and he spoke to engineering and was told they weren't aware of the issue at hand. I said then no one is listening in the field. But that is what happens when a company is also a partner with the company that sells the parts. Did you see the pic in reply to Tom
With relay.

 

[H012]

I also have to suspect the quality of the new relays those open style contacts are more robust then those in the new enclosed type.

 

[jim hardy]

I did speak with head of facilities sometime back and he spoke to engineering and was told they weren't aware of the issue at hand. I said then no one is listening in the field. But that is what happens when a company is also a partner with the company that sells the parts.

From the bottom it's hard to get attention
My old mentor said "Always start at the top"
but if you're going to ping the bureaucracy at that level you have to be doggone sure you're right
your best leverage so far is the photo of eroded contacts and the measurement of braking current you're about to make.
Do you guys have access to a storage oscilloscope ? A photo of voltage trace at C1-23N during braking would show rate of current rise. You'd want two, one showing the whole coastdown and another showing first half cycle.
If that's not possible,
wait until that relay has accumulated enough cycles to have killed it were your mod not there, examine its contacts, if it's not eroded badly you have proof that limiting braking current transient improves contact life and they have a design problem.

Got a picture of your resistor installed ?

I did see the picture of the two relays - one is a siemens-allis ?

I too prefer open relays, my plant used Westinghouse BF's. Trouble with them is during construction little pieces of wire insulation and pieces of Ty-Wrap that the electricians cut off fall into the open contacts and keep them from closing...

 

[H012]

From the bottom it's hard to get attention
My old mentor said "Always start at the top"
but if you're going to ping the bureaucracy at that level you have to be doggone sure you're right
your best leverage so far is the photo of eroded contacts and the measurement of braking current you're about to make.
Do you guys have access to a storage oscilloscope ? A photo of voltage trace at C1-23N during braking would show rate of current rise. You'd want two, one showing the whole coastdown and another showing first half cycle.
If that's not possible,
wait until that relay has accumulated enough cycles to have killed it were your mod not there, examine its contacts, if it's not eroded badly you have proof that limiting braking current transient improves contact life and they have a design problem.

Got a picture of your resistor installed ?

I did see the picture of the two relays - one is a siemens-allis ?

I too prefer open relays, my plant used Westinghouse BF's. Trouble with them is during construction little pieces of wire insulation and pieces of Ty-Wrap that the electricians cut off fall into the open contacts and keep them from closing...

One pic is resistor and the other pic is wire to cap. Got to stuff everything into duct.

 

[Tom.G]

OK Jim put 8 ohm resistor in place between cap and resistor. Braking unchanged it's OK
Voltage at C1 24 and return unchanged voltage drop off is still quick when running

Did installing the resistor have any effect on the contact arcing?

 

[jim hardy]

Friday night ... i bet the place is packed and he's swamped.

 

[Tom.G]

If you zoom in on this photo from Post #7, you will note at the left contact that the substrate metal is discolored from overheating. That would indicate either low contact pressure (faulty relay), contanimints (oil or particulate matter) or significant overcurrent. For arcing to cause that, there would have to be sustained arcing or highly repetitive arcing.

Side comment:
Many years ago I was on a project for electric trains, not the toys, the big ones like subways and rapid transit. At one point we had a batch of relays that would quite literally explode on contact closure. Close them into an 1200A load and there was a fireball and shrapnel everywhere. These were typical open frame construction with a return spring to open the contacts upon removing coil power and the movable contacts spring loaded on the armature. I finally tracked down the difference between the 'good ' and 'bad' batches to the spring that mounted the movable contacts on the armature. The bad batch had a weaker spring, hence lower contact pressure. Of course the relay mfg. was "informed." After a few days the mfg. reported back to us that it was an inventory problem on their part. Somebody and put the the wrong springs in the parts bin for that assembly line. I always wondered how many pieces were in that batch!

 

[jim hardy]

I've been digging for how to estimate subtransient reactance of induction motors.

Sparse...

Here's an article that mentions it, see page 12 of 14
http://people.physics.anu.edu.au/~bdb112/engn3225/Chapter_04_Motors_revA.pdf
i'm thinking six to ten X FLA should be the initial braking current spike into those capacitors ..
6 amp motor, 36 to 60 amp spikes, 10 amp relay contacts rated for 3X that much make current = 30 amps,
do you think that might erode them ? I doubt it's enough to weld them...

The over heating - I'm at a loss there.

old jim

 

[jim hardy]

Many years ago I was on a project for electric trains, not the toys, the big ones like subways and rapid transit. At one point we had a batch of relays that would quite literally explode on contact closure. Close them into an 1200A load and there was a fireball and shrapnel everywhere.

copper vapor follows same gas law as dynamite vapor ?

 

[Tom.G]

When you are talking of upwards of a thousand HP across the area of relay contacts poorly connected to each other, YES! There was a thick (2 inch?) Plexiglass shield between it and us.

 

[sophiecentaur]

I tried a solid state relay they didn't last long at all.

Perhaps the spec of your SSR was just not high enough?? Peak Volts can be very high when switching Inductive loads.
Washing machines have enormous SS switches which control the input power. That, to me, suggests you should expect to find a SS solution to this problem.

 

[jim hardy]

One pic is resistor and the other pic is wire to cap.

hmm top resistor is table and bottom one sweep ?

 

[H012]

hmm top resistor is table and bottom one sweep ?

Yes bottom is sweep

 

[H012]

I am positive the reason the SSR fail so soon on these machine is the repetitive cycling of the machines when we are busy average is about 15 seconds and the lack of adequate heat sinking on the MOSFETs is the problem.

 

[H012]

If you zoom in on this photo from Post #7, you will note at the left contact that the substrate metal is discolored from overheating. That would indicate either low contact pressure (faulty relay), contanimints (oil or particulate matter) or significant overcurrent. For arcing to cause that, there would have to be sustained arcing or highly repetitive arcing.

Side comment:
Many years ago I was on a project for electric trains, not the toys, the big ones like subways and rapid transit. At one point we had a batch of relays that would quite literally explode on contact closure. Close them into an 1200A load and there was a fireball and shrapnel everywhere. These were typical open frame construction with a return spring to open the contacts upon removing coil power and the movable contacts spring loaded on the armature. I finally tracked down the difference between the 'good ' and 'bad' batches to the spring that mounted the movable contacts on the armature. The bad batch had a weaker spring, hence lower contact pressure. Of course the relay mfg. was "informed." After a few days the mfg. reported back to us that it was an inventory problem on their part. Somebody and put the the wrong springs in the parts bin for that assembly line. I always wondered how many pieces were in that batch!

I have on many occasions taken one of these enclosed relays apart to see the nature of the NO failure. The spring on any brand relay contact of the class that are used in these machines are very light. The contact just pivots on the one spring. Would definitely be better if there was a spring on each end of contact, but that's my opinion
I'm electrical engineer. I can understand more how contact bounce can occur. Or just not able to be firmly mated to the other contact.

 

[jim hardy]

guys some speculation here, followed by a question...

i've been obsessed by the thought the contacts are being eroded by current from the motor
and have tried to operate the braking sequence millisecond by millisecond in my head..
loooking for a relay race between the NO contacts opening and the NC contacts closing
it is necessary for the NO's in upper left to clear before the NC's below close , else we have a near dead short across the supply as shown in post #43

what if... entertain this thought experiment for a moment ... HO12 answered this long ago when he said

H012 said: ↑
The only fact I know is that the NC arcing occurs when they open, only because I can see it.

when what opens ? The NC's or the NO's ? We established by test that there's no current through the NC's when they open by measuring voltage at junction of the two capacitors if i understood. It drops to zero after motor starts and remains so until braking.

So if the arcing is observed at braking time when the NO's in upper left open, that's not surprising because they are interrupting motor current and it's an induction motor.

Anybody who's arc-welded knows an arc can persist surprisingly long

so in the thought experiment, think millisecond by millisecont from the instant the S relay plunger starts to travel to de-enegrgized position
1. NO contact opens a ten-thousandth of an inch establishing an arc
2. NO contact continues its travel, arc gets longer
3. NC contact makes initial contact , connecting motor to capacitors which are nearly a dead short
4. Current through NC contact consists of current from motor plus any leftovers from the arc - at this instant NC does not yet have full contact pressure so some melting might occur
5. NC that's NO contact continues widening its airgap, quenching the arc (sorry for the mistake )
6. NC contact establishes full contact pressure and commences to cool whatever metal was melted in 4.

Now here's the speculation
Which comes first ? 4 or 5 ? If NC makes before NO has extinguished its arc, we have a short across supply through a not quite extinguished arc and a not well seated NC contact that's still bouncing... see post #87

Is that scenario plausible?

so the relay race i was looking for isn't contact vs contact mechanical travel overlap but contact travel vs arc quenching time overlap.

How does energy deposition between two arcs in series divide?
Is this plausible, guys?
If so, a snubber across motor as in post #89 might help NC NO quench the arc before NC makes.('nother durn mistake )

That old saying, before you figure out what it is you'll figure out a lot of things it ain't.

I am positive the reason the SSR fail so soon on these machine is the repetitive cycling of the machines when we are busy average is about 15 seconds and the lack of adequate heat sinking on the MOSFETs is the problem.

If the SSR is SCR based and can't turn off the NO contact until a current zero crossing happens,
then there's an interval where it connects 1000 uf right across the line which could be a bodacious surge.

Looking for holes in that line of thinking
and any thoughts on how to test for it.

old jim

 

[jim hardy]

I'm electrical engineer. I can understand more how contact bounce can occur. Or just not able to be firmly mated to the other contact.

okay i apologize if i seemed to be talking down, that was not my intent
i think in simple steps and it's the only way i know to communicatedo you guys have an oscilloscope?

If you get a chance , see how much current we get on coastdown (volts at resistor or capacitor centertap?)

and a sanity check on my previous post ? we crossed in the mail.

old jim

 

[H012]

guys some speculation here, followed by a question...

i've been obsessed by the thought the contacts are being eroded by current from the motor
and have tried to operate the braking sequence millisecond by millisecond in my head..
loooking for a relay race between the NO contacts opening and the NC contacts closing
it is necessary for the NO's in upper left to clear before the NC's below close , else we have a near dead short across the supply as shown in post #43

what if... entertain this thought experiment for a moment ... HO12 answered this long ago when he said
when what opens ? The NC's or the NO's ? We established by test that there's no current through the NC's when they open by measuring voltage at junction of the two capacitors if i understood. It drops to zero after motor starts and remains so until braking.

So if the arcing is observed at braking time when the NO's in upper left open, that's not surprising because they are interrupting motor current and it's an induction motor.

Anybody who's arc-welded knows an arc can persist surprisingly long

so in the thought experiment, think millisecond by millisecont from the instant the S relay plunger starts to travel to de-enegrgized position
1. NO contact opens a ten-thousandth of an inch establishing an arc
2. NO contact continues its travel, arc gets longer
3. NC contact makes initial contact , connecting motor to capacitors which are nearly a dead short
4. Current through NC contact consists of current from motor plus any leftovers from the arc - at this instant NC does not yet have full contact pressure so some melting might occur
5. NC contact continues widening its airgap, quenching the arc
6. NC contact establishes full contact pressure and commences to cool whatever metal was melted in 4.

Now here's the speculation
Which comes first ? 4 or 5 ? If NC makes before NO has extinguished its arc, we have a short across supply through a not quite extinguished arc and a not well seated NC contact that's still bouncing... see post #87

Is that scenario plausible?

View attachment 103718

so the relay race i was looking for isn't contact vs contact mechanical travel overlap but contact travel vs arc quenching time overlap.

How does energy deposition between two arcs in series divide?
Is this plausible, guys?
If so, snubber across motor as in post #89 might help NC quench the arc.

That old saying, before you figure out what it is you'll figure out a lot of things it ain't.
If the SSR is SCR based and can't turn off the NO contact until a current zero crossing happens,
then there's an interval where it connects 1000 uf right across the line which could be a bodacious surge.

Looking for holes in that line of thinking
and any thoughts on how to test for it.

old jim

Here is a pic. of a SS relay (bad)

 

[jim hardy]

oops step 5 above should say "NO contact continues widening.." instead of NC.. believe me it's frustrating to be so awkward...
will fix now
then look at ss relay picture thanks !

 

[H012]

oops step 5 above should say "NO contact continues widening.." instead of NC.. believe me it's frustrating to be so awkward...
will fix now
then look at ss relay picture thanks !

Jim I found this doesn't match schematic.Iook at pic. I tried to upload pic site won't let me Do you have Gmail?

 

[H012]

Jim I found this doesn't match schematic.Iook at pic. I tried to upload pic site won't let me Do you have Gmail?

I got it to upload. Jim the black and blue wire are both coming from same hot at all times terminal strip in wire duct? Am I dumb!

 

[jim hardy]

I am positive the reason the SSR fail so soon on these machine is the repetitive cycling of the machines when we are busy average is about 15 seconds and the lack of adequate heat sinking on the MOSFETs is the problem.

still trying to figure out that SSR

Mosfets. Hmmm

the little white MOC3012's are optocouplers ,
http://www.ti.com/lit/ds/symlink/moc3009.pdf
probably they make gate drive for whatever are those big power semiconductors ?
Do those have a part number ?

I'm a little behind you HO12...

Do you have Gmail?

check your "Inbox" button at top...

 

[H012]

still trying to figure out that SSR
View attachment 103732

Mosfets. Hmmm
View attachment 103726

the little white MOC3012's are optocouplers ,
http://www.ti.com/lit/ds/symlink/moc3009.pdf
probably they make gate drive for whatever are those big power semiconductors ?
Do those have a part number ?

I'm a little behind you HO12...

check your "Inbox" button at top...

I will look at PN# at home can't see it without magnification. Thanks

 

[jim hardy]

gotcha. Can you tell any difference in arcing ?

I got it to upload. Jim the black and blue wire are both coming from same hot at all times terminal strip in wire duct? Am I dumb!

not at all, just learning the details of your machine.
Machieavelli says a good prince knows not just every hill of his princedom , he knows every rock and every shrub on every hill of it. See my avatar...

 

[H012]

gotcha.Can you tell any difference in arcing ?

not at all, just learning the details of your machine.
Machieavelli says a good prince knows not just every hill of his princedom , he knows every rock and every shrub on every hill of it. See my avatar...

View attachment 103736

View attachment 103739

I don't think so because wouldn't run anyway. I went just for the heck of it and took out the black wire. As I thought runs and breaks fine. I did this on a different machine. Not the one with the resistor as someone is bowling on it. The arcing is still there but it's not blueish white it's white. I have a chassis I'm finishing up with new relays. Going to put resistor on that machine
I put the new relays in.

 

[jim hardy]

Is your dead SSR shorted
3 to 4
4 to 7
5 to 6

all or none of the above?

 

[H012]

Is your dead SSR shorted
3 to 4
4 to 7
5 to 6

all or none of the above?

Jim I don't check them. Same as always sweep doesn't work when bowler bowls. The sweep really is tough on relays. Thing is it's not heavy. Just has to run 3 times for every one time of the table.like tonight these machines have been running more or less since 9 am

 

[Tom.G]

ref Post #132

I don't think so because wouldn't run anyway. I went just for the heck of it and took out the black wire. As I thought runs and breaks fine.[/color] I did this on a different machine. Not the one with the resistor as someone is bowling on it. The arcing is still there but it's not blueish white it's white. I have a chassis I'm finishing up with new relays. Going to put resistor on that machine
I put the new relays in.

I lost track of something here. If the removed Black wire refers to the sketch showing Black and Blue duplicate feed to the S and T relays, that shouldn't make any difference if the schematic matches the real world.[/color]

HEY GUYS, THAT REDUCED THE ARC TEMPERATURE BY 1000 TO 2000 DEGREES C. On the right track!

ref post #129
@jim hardy

Mosfets. Hmmm

TRIACs.

 

[H012]

ref Post #132I lost track of something here. If the removed Black wire refers to the sketch showing Black and Blue duplicate feed to the S and T relays, that shouldn't make any difference if the schematic matches the real world.

HEY GUYS, THAT REDUCED THE ARC TEMPERATURE BY 1000 TO 2000 DEGREES C. On the right track!

ref post #129
@jim hardy

TRIACs.

Exactly my thoughts. That's why I took it out.
Because it didn't match. When I leave here I want whomever not to have guess. To what it's supposed to be.

 

[Tom.G]

Exactly my thoughts. That's why I took it out.
Because it didn't match.

At least we agree that as a wire just in parallel with another wire, it shouldn't make any difference. Sounds like it wasn't just in parallel. Tracking down where things are really connected may find other anomalies or the root cause of the relay arcing problem.

Unfortunately in the real world, we sometimes have to go with what works and move on.

 

[H012]

At least we agree that as a wire just in parallel with another wire, it shouldn't make any difference. Sounds like it wasn't just in parallel. Tracking down where things are really connected may find other anomalies or the root cause of the relay arcing problem.

Unfortunately in the real world, we sometimes have to go with what works and move on.

Common sense I say. Good way to put it. Can't go around trying to understand why people do what they do. Thanks Tom!

 

[jim hardy]

Im still not clear, pardon me but I'm always a day behind in any conversation

Did the arc get less intense? White and small vs blue and big? Resistor ought to do that.

I never did get it real clear whether you can see arc on NC's or NO's or both...

If you have that motor run capacitor, tack it across motor main winding and see if arc changes. Dont leave it there without some resistance in series,

but if it makes arc smaller take a look at this product

http://www.digikey.com/product-sear...t=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

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

getting behind again

great working with all you guys
and i hope @Svein is still here - he told us so !

I like to understand a machine before i tinker with its design , that's all...

 

[H012]

Im still not clear, pardon me but I'm always a day behind in any conversation

Did the arc get less intense? White and small vs blue and big? Resistor ought to do that.

I never did get it real clear whether you can see arc on NC's or NO's or both...

If you have that motor run capacitor, tack it across motor main winding and see if arc changes. Dont leave it there without some resistance in series,

but if it makes arc smaller take a look at this product

http://www.digikey.com/product-sear...t=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

http://www.cde.com/resources/catalogs/Q-QRL.pdf
View attachment 103743

getting behind again

great working with all you guys
and i hope @Svein is still here - he told us so !

I like to understand a machine before i tinker with its design , that's all...

 

[H012]

As I stated the arcing at NC was a blueish white now it,s just white as far as intense
I can't really tell the arc happens so fast. There is a few relays that the NO do arc but these relays have some age one them. Jim I had looked into the QuechArc but the formulas are over my head. I,m still going to get the run cap and try it. Thanks I will let you know.

 

[jim hardy]

As I stated the arcing at NC was a blueish white now it,s just white as far as intense

Ahhh it's at the NC - Thanks !
Since we don't have a peak capture ammeter or o'scope your observed intensity is our measure. Those Quencharc equations do look scary
Had you needed instead to protect the NO contacts from arcing when they open, the approach i use is this simpler one
...objective is to give the load current a path into a capacitor ( instead of through the contacts) for those first few microseconds while the contacts separate those first few thousandths of an inch
that way the inductive kick charges the capacitor instead raising the voltage enough to strike an arc
just like points in a car ignition are protected by the condenser

the car ignition uses around 0.22 uf for coil current of maybe two amps, ~ 0.1 uf per amp

what rate of voltage rise does that give ?
i = c X ΔV/ΔT
2 = .22 X^10-6 X ΔV/ΔT

ΔV/ΔT = 2/.22 X^10-6 = around 9 volts per microsecond
.1uf per amp would be 10 volts per microsecond
and that seems to protect the contacts in automobile points, which cycle a few hundred times per second
your six amp motor by that criteria, 0.1uf per amp, would get about 0.6 uf

so i just picked a Quencharc with a little more capacitance than that
and lowest resistance they offer
because the voltage across that resistor appears across the contacts and 6 amps X 22 ohms is 132 volts at instant of contact opening,
a lot less than the full inductive kick would make.

Hope that helps in your next relay adventure ...

old jim

 

[H012]

Ahhh it's at the NC - Thanks !
Since we don't have a peak capture ammeter or o'scope your observed intensity is our measure.Those Quencharc equations do look scary
Had you needed instead to protect the NO contacts from arcing when they open, the approach i use is this simpler one
...objective is to give the load current a path into a capacitor ( instead of through the contacts) for those first few microseconds while the contacts separate those first few thousandths of an inch
that way the inductive kick charges the capacitor instead raising the voltage enough to strike an arc
just like points in a car ignition are protected by the condenser

the car ignition uses around 0.22 uf for coil current of maybe two amps, ~ 0.1 uf per amp

what rate of voltage rise does that give ?
i = c X ΔV/ΔT
2 = .22 X^10-6 X ΔV/ΔT

ΔV/ΔT = 2/.22 X^10-6 = around 9 volts per microsecond
.1uf per amp would be 10 volts per microsecond
and that seems to protect the contacts in automobile points, which cycle a few hundred times per second
your six amp motor by that criteria, 0.1uf per amp, would get about 0.6 uf

so i just picked a Quencharc with a little more capacitance than that
and lowest resistance they offer
because the voltage across that resistor appears across the contacts and 6 amps X 22 ohms is 132 volts at instant of contact opening,
a lot less than the full inductive kick would make.

Hope that helps in your next relay adventure ...

old jim

Thanks Jim

 

[Tom.G]

Just measured a car ignition coil primary. 0.5 Ohm, 4.9mH.

 

[jim hardy]

Just measured a car ignition coil primary. 0.5 Ohm, 4.9mH.

Old battery and points coil? Must use external "Ballast" resistor..
half the inductance of the motor you measured.

found an old Quencharc datasheet that includes the "how to" attachment i remember reading years ago
http://www.panconcorp.com/PDFs/capacitors/QRL-Quencharc.pdf

 

[Tom.G]

Old battery and points coil? Must use external "Ballast" resistor..

From a '97 Ford Crown Victoria (Taxi Cab/Police Interceptor). Computer driven, V8 engine, 2 coil assemblies, each having 2 center-tapped coils so that each coil connects to 2 spark plugs. That means the coil fires when the associated pistons are at TDC, once per engine revolution. No ballast resistors or caps visible or shown in the shop manual, but the Engine Control Computer is shown as a black box.

 

[jim hardy]

Probably CD ignition on one that new


Battery and coil is sized i as best i recall for 2 amps running, twice that during cranking by bypassing the ballast resistor with an aux contact on starter solenoid,
on the premise you need all the spark you can get
because engine is cold and battery voltage is probably sagging as starter huffs and puffs pushing that piston up to TDC on compression stroke, right when you need voltage most...

 

[Tom.G]

Entirely possible. Even likely.

 

[H012]

Old battery and points coil? Must use external "Ballast" resistor..
half the inductance of the motor you measured.

found an old Quencharc datasheet that includes the "how to" attachment i remember reading years ago
http://www.panconcorp.com/PDFs/capacitors/QRL-Quencharc.pdf

Thanks Tom. Well today before I saw this post I put a chassis in the lane Jim had me put the resistor in with 2 new Table and Sweep relays The NO contacts are still arcing. I wanted to eliminate the old relays. As the contacts being the cause.

 

[Tom.G]

Okaayy... We seem to be switching back and forth on whether it's the NO or NC contacts that are arcing. I suspect they are both arcing under different conditions/faults on different machines, but so far it is very confusing. Getting this settled is important because appropriate fixes depend on the timing and specific conditions that the arcs occur. It would be extremely useful if you could post a video of a Sweep relay for a whole sweep cycle showing arcing. Ideally using one of the old style open frame relays so we can see the contact movements and where the arcing occurs, and infer where in the operating cycle it all happens.