24V issues in coin box?? Need help.

[2Biz]

If you haven't done this already, check across two transformers on the same output of each one, and you should read 0V, and do the same with both output terminals (for example X1 on bay 1 and x1 on bay 2). If you can go across all the bays and all the terminals that way and see no voltage, everything is "in phase." If they aren't, and if all the "common" sides of all the transformers are interconnected somewhere it's neutralizing the voltage when two bays with inverse wiring are switched to the same function at the same time. The fix is as simple as making sure the same leg of 120VAC is on the same side on each transformer.

According to my voltages, it indicates my transformers are out of phase. I tested X1 bay 1 with x1 bay 2 and didn't get 0v like mentioned here. I got 44v for some odd reason...I even disconnected the common ties and it didn't change. As far as the cancelling out of voltage when 2 or more bays are selected on the same function, I didn't get that either. Each bay read 24v when all bays were on say FB...

So I guess all this is over my head...Its not making sense. So count me out of this discussion. I obviously don't know how it all works. Just that mine works, even though it doesn't make sense!

Good luck with your problem....PLJ....Sorry I wasn't of much help. Just confused myself more than I need to be!

 

[MEP001]

According to my voltages, it indicates my transformers are out of phase. I tested X1 bay 1 with x1 bay 2 and didn't get 0v like mentioned here. I got 44v for some odd reason...I even disconnected the common ties and it didn't change. As far as the cancelling out of voltage when 2 or more bays are selected on the same function, I didn't get that either. Each bay read 24v when all bays were on say FB...

So I guess all this is over my head...Its not making sense. So count me out of this discussion. I obviously don't know how it all works. Just that mine works, even though it doesn't make sense!

Good luck with your problem....PLJ....Sorry I wasn't of much help. Just confused myself more than I need to be!

If you check the lines into the transformers just like you checked the lines out, you'll probably find the same thing I mentioned before, that the legs going to them are not all the same. When I worked for a distributor, we did a retrofit of a wash to Dixmor timers, and the same problem Paul described happened. The old timers didn't seem to care that the voltage fluctuated wildly, but some of the Dixmors would go blank and the bay would shut off if certain things were selected together.

 

[PaulLovesJamie]

Well I did some voltage measurements this morning, and the end result was that I had to come home and take out some frustration aggression at the wood shed. (I cut & hand split about 5 cords of oak every year) Apart from splitters elbow I feel better.
But apparently I do have some issues in my coin boxes.
Now to figure out which ones matter, and what the simplest/ideal wiring is.

So first of all, you guys are a huge help, Thank you. I owe you a beer, no doubt.
And secondly I'll quote 2Biz' comments this morning because this is exactly how I'm feeling, plus he cracked me up:

Ok..So now even I'm a little confused.

At this point, I wonder if it matters how its wired

What I have works but is now confusing me....

So I guess all this is over my head...Its not making sense. So count me out of this discussion. I obviously don't know how it all works. Just that mine works, even though it doesn't make sense!

Just confused myself more than I need to be!

 

[PaulLovesJamie]

Bay1 is the wild leg

One of the lines into the transformer for Bay1 is the wild leg, 216V.
For some strange reason I thought the black wires were 120V, the red was the wild leg @ 216V. And yes in fact it is true at my wash... except for bay 1. Bay 1 has 2 black wires feeding the transformer just like every other bay. And when I trace them back, one is the wild leg.

 

[PaulLovesJamie]

Bay2 is out of phase.

Bay2 X1 to Bay4 X1 measures 27 volts - I'm out of phase!
No way! When I installed EV timers in bays 3,4,5 two years ago, I checked this and it was fine!!!
Oh, wait a minute... I probably only checked bays 3/4/5 because my wiring is in 2 separate control boxes in the ER and I dont have a long multimeter probe. (made one for myself this morning.)
I probably did the totally stupid thing and assumed that the other bays would be wired identically. Knucklehead! What a maroon!

 

[PaulLovesJamie]

Despite what mjwalsh said, you're not going to see 24V if you take a reading from the transformer to the ground because your transformers are wired at 220. EACH OUTPUT from the transformer will read 12VAC to ground. He's wrong that reading 12V indicates a problem.

I confirmed this morning via multimeter that the Bay4 transformer is served by two 121V lines. I removed the fuse and measured voltage from each of the 4 output terminals to the grounding lug. Two were 0V (as expected), and the 2 that are wired together measure 24V. Maybe this has something to do with the way my transformers are "grounded" (see next post.)
Doh! Sorry, I just realized they are wired together, those are probably the 2 outputs MEP mentions, I'll separate them tomorrow and see if they are 12V each.

Quite often when 2 people dont agree it indicates that there is more that I don't understand...
LOL, maybe Mike made the same mistake I did

 

[PaulLovesJamie]

Are my transformers grounded??

Are my transformers grounded? My first thought was to say yes. Then I looked at and traced the wires in the lower left corner of the pic of my transformer.
The green ground wire just goes to the frame/housing of the transformer.
One white wire goes to the terminal block going out to the bay, its the "neutral" wire for the bay controls.
Second white wire goes to the motor contactor (I think it is just grounding the contactor itself.)
(FYI the small red&black wires are powering a relay for my weep system, not relevant to these discussions I think.)

So the transformer is screwed to the mounting plate, which is metal. And the grounding lug in the control box is screwed to the mounting plate. So that would mean that my transformer IS grounded, but it is done through the mounting plate??
I confirmed that the mounting plate is in fact grounded; I do get a 27VAC reading from the 24V side of the transformer when I scratch the other probe into the mounting plate.
I'm thinking I dont like that! Is it standard to ground the mounting plate in the control box, and to use that as a grounding point??

 

[PaulLovesJamie]

Sorry for all these posts & details, but this is really helping me a lot.

 

[PaulLovesJamie]

Transformer voltage supply wires from the motor contactor

At the moment my transformers are all powered by wires jumped over from the motor contactor. I cant think of a good reason to do it this way, other than one less breaker and less wire.
I'm thinking my 24V transformers should not be on the same circuit breaker as the motor for the HP pump, I can see no benefit to the way it is wired other than its one less breaker and less wire. As it is I might be getting inductive feedback from the pump motor?
I'm thinking I should just put the transformers on their own circuit. Am I missing something?

 

[PaulLovesJamie]

Conclusions?

So my conclusion (so far?) is that there are a few additional improvements I need to make:

1) Run a new circuit to supply all 24V transformers.
2) Change to 120V supply to transformers. Simpler for me to understand; no significant reason to run them 220.
3) Make absolutely certain all transformers are on the same phase, and its not the wild leg.
4) All transformers will be grounded.
5) Install snubbers (on order); based on the reading I've done this should be standard equipment.

Does that sound correct to you ?

Question: If I run all 5 24V transformers from 1 circuit breaker, the commons would in fact all be wired together. Given that I convert them all to 120V this would be a good thing, right?

You guys have been very helpful, thanks for your attention and patience with my limited electrical knowledge.

 

[mjwalsh]

Are my transformers grounded? My first thought was to say yes. Then I looked at and traced the wires in the lower left corner of the pic of my transformer.
The green ground wire just goes to the frame/housing of the transformer.
One white wire goes to the terminal block going out to the bay, its the "neutral" wire for the bay controls.
Second white wire goes to the motor contactor (I think it is just grounding the contactor itself.)
(FYI the small red&black wires are powering a relay for my weep system, not relevant to these discussions I think.)

So the transformer is screwed to the mounting plate, which is metal. And the grounding lug in the control box is screwed to the mounting plate. So that would mean that my transformer IS grounded, but it is done through the mounting plate??
I confirmed that the mounting plate is in fact grounded; I do get a 27VAC reading from the 24V side of the transformer when I scratch the other probe into the mounting plate.
I'm thinking I dont like that! Is it standard to ground the mounting plate in the control box, and to use that as a grounding point??

Paul & others,

http://forum.allaboutcircuits.com/archive/index.php/t-32375.html

Note ... that the linked discussion is not just about personal safety but also could be helpful in protecting electronics in some cases. In my case with our car wash ... I think I will leave the proven way that Specialty (the factory) originally did the wiring of the transformers. It just seems simpler with just one hot on just one side of the secondary even on a 240 VAC primary side transformer.

Don't get me started on how we built on the factory wiring so a backup pump setup (our l'l robot) is on standby with a simple toggle switch or two & a quick disconnect. Or on the wiring & 3 way valves required to use 3 or 4 pumps for quicker wash down. Also customized decals & lights so we don't get after not using the modifications for awhile (sometimes forgetful ya know).

mike walsh www.kingkoin.com

 

[MEP001]

I've seen before where a car wash was wired with 240V going to the transformers and the common leg was grounded, I don't know why it works and doesn't act as a direct short but it does.

I don't feel you need to run a separate circuit for the transformers. I've worked on literally hundreds of different washes, and all but a couple branch right off the contactor to power the transformer at 240V. I feel your quickest, easiest attempt to solve this would be to remove the green ground wire and make sure all the legs into the transformer are the same phase. If that doesn't do it, you could always rewire it like you said.

 

[2Biz]

One of the lines into the transformer for Bay1 is the wild leg, 216V.
For some strange reason I thought the black wires were 120V, the red was the wild leg @ 216V. And yes in fact it is true at my wash... except for bay 1. Bay 1 has 2 black wires feeding the transformer just like every other bay. And when I trace them back, one is the wild leg.

I will chime in now that I learned a little since yesterday! I went back to the wash and discovered I have the exact same issue as you. 2 of my transformers are wired using the wild (208V) leg. AND since the timing of the cycles of the 208v wild leg are such that they measure 240v when checking voltage to one of the other 120v lines, I thought all was good. Bays 1 and 3 use (2) 120v lines for input and bays 2 and 4 use a 120v line and a 208v line. Keep in mind that the 120v and 208v line still reads 240v when checking across them. That added to my confusion! How could somebody be so careless when they hooked it up?

But going back to what Mep said, even though he is exactly right about how to phase transformers, I didn't get the "Cancelling out of voltage when all bays were on the same function. Or any of the same functions. You would think it would be like this?!?!?!?! But not...I read 24-26v on each circuit even though all 4 bays are running the same function...Go figure.

Now its the Million dollar question. Does it matter? Way to "Bird Dog" the problem PLJ....If changing your wiring around fixes the problem, let us know. I really need to fix mine, its just not high on the priority list right now. Cause mine "Appears" not to be broke! Just not 100% correct!

 

[JGinther]

Paul, when your headache is gone from reading all of this, try a new rotary switch. When a switch goes bad, it can pull the 24V down to ground internally since it is bolted to the meterbox door. Your fuse is too big to protect your transformers, so get a four amp for the transformer. If your timer output is rated for less, go with that number instead. The reason your bill validators are cycling is that the voltage is being pulled down. Each time the motor cycles on the validator the amp draw pulls it even lower and the units 'loose power', and then the motor turns off, which makes the voltage go up a bit and the validator 'boots' up and cycles the motor again....repeat. If you have an ammeter, put it on the hot 24V line and have someone very slowly go through each function. Give a couple of minutes per function. If you see one that pulls a higher amount, the coil for that function may also be the issue (could be contactor, solenoid coil, relay, or whatever!) Another problem I have seen cause this is a soap leak on a solenoid block.... The soap is conductive enough to short from one terminal of a coil to another after the leak gets going enough...

Regarding the electrical talk, I might chime in that it doesn't matter what voltage or leg you wire a transformer too, the only important thing is that it is wired to the correct taps for the voltage coming in. A service with a wild leg (high leg delta) would require using a 240 V transformer or a multitap transformer wired to the 240V tap. A Wye service would use 208 Volt taps or a 208 volt transformer. If you used the 'wrong' tap or transformer, chances are you wouldn't have any problems, as the secondary (output) voltage would be off the 24V mark by up to 4 volts. Most electronics and loads would not have a problem with this.

Regarding grounding ouput voltage of a transformer, you can ground any single leg coming out of a transformer (you just can't ground two!). Since transformers are inductive, the secondary (output) is truly isolated from the incoming power, meaning that there is no reference to ground. Grounding any leg of the secondary makes that wire a 'neutral' wire because it no longer has a voltage reference to ground (it is grounded). However, the other leg becomes the 'hot' leg and will be a direct short if it comes in contact with ground.

Phasing in a bank of transformers is not important unless you are trying to balance loads for load distribution (not applicable in a car wash pumpstand). If you wish to make a 'common bus' along a bunch of solenoids that are each sourced from a different transformer, you can do that, but you can't forget to give the solenoid a reference back to its own transformer (you have to tye all of the commons together somewhere). If the transformers are out of phase with eachother, it will still work. Since transformers are 'isolated' individual circuits, the voltage is only in reference to its own source - not another source (other bays transformer) - even if one leg is grounded on each transformer. The only time you will ever have a problem is if some electronic device is truly using the ground to conduct its own internal electricity - which is a no no. A gfci would trip if an electronic device like this were hooked up to it...

 

[PaulLovesJamie]

Paul, when your headache is gone from reading all of this, try a new rotary switch. When a switch goes bad, it can pull the 24V down to ground internally since it is bolted to the meterbox door.

OK, now that makes sense - now that you've said it out loud

Your fuse is too big to protect your transformers, so get a four amp for the transformer. If your timer output is rated for less, go with that number instead.

Agreed, I neglected to put that on my list. Switching to 4A fuses.

The reason your bill validators are cycling is that the voltage is being pulled down. Each time the motor cycles on the validator the amp draw pulls it even lower and the units 'loose power', and then the motor turns off, which makes the voltage go up a bit and the validator 'boots' up and cycles the motor again....repeat. If you have an ammeter, put it on the hot 24V line and have someone very slowly go through each function. Give a couple of minutes per function. If you see one that pulls a higher amount, the coil for that function may also be the issue (could be contactor, solenoid coil, relay, or whatever!)

Well thats easy to test, thanks! Will do this afternoon!

The only time you will ever have a problem is if some electronic device is truly using the ground to conduct its own internal electricity - which is a no no. A gfci would trip if an electronic device like this were hooked up to it...

Lots more good info, thanks.

One thing I've wondered in the past is why we dont install more gfci devices. I suppose the answer is that if everything is wired correctly gfci's would be a waste of time & money. But we all know that things are not always done right, wire casings abrade, murphy and entropy rule. Seems more gfci devices would be cheap insurance + a cheap way to alert me that something is amiss.

Anyway, more to look at and time to start implementing some changes.

 

[2Biz]

Regarding the electrical talk, I might chime in that it doesn't matter what voltage or leg you wire a transformer too, the only important thing is that it is wired to the correct taps for the voltage coming in. A service with a wild leg (high leg delta) would require using a 240 V transformer or a multitap transformer wired to the 240V tap. A Wye service would use 208 Volt taps or a 208 volt transformer. If you used the 'wrong' tap or transformer, chances are you wouldn't have any problems, as the secondary (output) voltage would be off the 24V mark by up to 4 volts. Most electronics and loads would not have a problem with this.

Regarding grounding ouput voltage of a transformer, you can ground any single leg coming out of a transformer (you just can't ground two!). Since transformers are inductive, the secondary (output) is truly isolated from the incoming power, meaning that there is no reference to ground. Grounding any leg of the secondary makes that wire a 'neutral' wire because it no longer has a voltage reference to ground (it is grounded). However, the other leg becomes the 'hot' leg and will be a direct short if it comes in contact with ground.

Phasing in a bank of transformers is not important unless you are trying to balance loads for load distribution (not applicable in a car wash pumpstand). If you wish to make a 'common bus' along a bunch of solenoids that are each sourced from a different transformer, you can do that, but you can't forget to give the solenoid a reference back to its own transformer (you have to tye all of the commons together somewhere). If the transformers are out of phase with eachother, it will still work. Since transformers are 'isolated' individual circuits, the voltage is only in reference to its own source - not another source (other bays transformer) - even if one leg is grounded on each transformer. The only time you will ever have a problem is if some electronic device is truly using the ground to conduct its own internal electricity - which is a no no. A gfci would trip if an electronic device like this were hooked up to it...

Very good explanation. I asked the Electrical Engineer/Supervisor this morning where I work about this and he said the same exact thing as you did. Thanks for making this clear and giving us something we can all reference back to!

 

[PaulLovesJamie]

Reporting back some results

If you have an ammeter, put it on the hot 24V line and have someone very slowly go through each function. Give a couple of minutes per function. If you see one that pulls a higher amount, the coil for that function may also be the issue (could be contactor, solenoid coil, relay, or whatever!)

OK, using my el-cheapo clamp ammeter I measured amperage draw on the timed load wire from the dixmor LED7 timer.
Bays 4 & 5 had almost identical readings, differences of .01-.03A. (one exception noted further down).
I left each function run for about 2 mintues; none of the readings varied more than .01A.

Stop 0A
TC, Engine, PS (2 dema 401P): 1.26A
FB (2 dema 401P): 1.17A
HP Soap & clearcoat (kip manifold block): .76A
HP Rinse .37A (1.41A with cold rinse 414P solenoid engaged)
SFR (1 M&M d265dbun solenoid): .84A

I looked up the electrical specs for dema coils - for example the 401P lists holding amps of .75 @ 60Hz. Since my readings are lower than that I'm assuming that I'm OK here. Intend to check the other bays later, but at the moment 4&5 are the bays where I recently had electronics failures so I'm focusing on that.
Also not sure why the FB drew less amps than the other LP functions, it is set up the same.

The one exception I mentioned: PreSoak drew 1.28A in bay 4, 1.05A in bay 5. Not sure why or if thats a significant difference, but it has my attention because when the timer for bay5 failed, I think the customer was switching from PS to HP Soap. I intend to check the solenoids separately tomorrow.

 

[PaulLovesJamie]

voltage with breaker off

This next reading confuses me.
With the circuit breaker turned OFF, I checked the incoming voltage on the motor contactor. Son of a B, 24 volts! Not possible???

Terminal Breaker on Breaker off
L1 216V 24V
L2 121V 34V
L3 121V 24V

Does this mean I have... what?? I did not expect to see any voltage in the supply wires when the breaker was off, and I dont have a clue what it means, but I dont like the sound of it!

Here's a couple pics of the motor contactor:

[/URL][/IMG]

[/URL][/IMG]


(The wire on the NO terminal is for a solenoid on the water supply to my gravity tank - which, yes, I added about a year or 2 ago.)
The white wire on terminal A1 (at top left corner in 2nd picture) is the 2nd white wire coming off the 24V side of my transformer, which I mentioned in post #27 that I assumed was simply grounding the motor contactor itself.
Is it possible that I'm backfeeding voltage through that wire? Through the gravity tank solenoid wiring?
Why does the one one terminal read 35V??
Bad motor contactor?
Yikes. I need to check for this voltage on all 5 bays.

 

[MEP001]

I'd turn off power to all the bays and test for that voltage again. It might be happening because the commons are bonded to the pumpstands. I'd still recommend removing those grounding jumpers.

No, the voltage isn't caused by a bad contactor.

 

[JGinther]

Does this mean I have... what?? I did not expect to see any voltage in the supply wires when the breaker was off, and I dont have a clue what it means, but I dont like the sound of it!
(The wire on the NO terminal is for a solenoid on the water supply to my gravity tank - which, yes, I added about a year or 2 ago.)
The white wire on terminal A1 (at top left corner in 2nd picture) is the 2nd white wire coming off the 24V side of my transformer, which I mentioned in post #27 that I assumed was simply grounding the motor contactor itself.
Is it possible that I'm backfeeding voltage through that wire? Through the gravity tank solenoid wiring?
Why does the one one terminal read 35V??
Bad motor contactor?

Probably just ghost voltage, but there is a possibility that you have a wiring problem still. To eliminate ghost voltage, use a solenoid type of meter instead of a high impedance multimeter. They have such high impedance that they read voltage that doesn't have any actual potential to power anything. It usually is just coming from natural inductance of the power wires as they twist through the conduit with other power wires. If you don't have a solenoid type meter, short the lines out (make sure the power is off first!) and see if there is any actual current... Chances are there won't be any. If another fuse blows or something smokes, you will likely find the source of your wiring problem!