Frying contactor

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mrdoctorm
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Frying contactor

Post by mrdoctorm »

Hi,
I've built out a 2 element, 2 pump system, based loosely somewhere between the Cal electric brewery and the systems from ebrewsupply. I finally got the system built and wired and got the BCS-462 all set up. I've done point to point checks and even had the controller running all the individual parts in auto. But once I get the system running (with one element heating water and one pump running) for about 10 minutes the 240V-40A contactor with 120V coil blows. I hear a pop and the contactor starts smoking. I thought maybe I had a bad part so I reordered it and the same thing happened. So now I'm at a loss. When it blows the side with the 120V coil is definetly very hot. I'm not sure whats causing this to happen. I've attached my wiring diagram (which I have verified).
brewing controller rev 4.pdf
(81.14 KiB) Downloaded 347 times
Am I just missing something obvious? The 40A breaker at my panel didn't pop either time. Could the contactor be getting too hot in the panel so it reduces it's amperage rating. Do I need a fan blowing through the panel. I've got a heat sink on the SSRs but nothing else. Or is there some wiring I need to change.
I'm getting super frustrated and could really use the help.
Thanks for taking the time to look at this,
Justin
JonW
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Re: Frying contactor

Post by JonW »

I'm not seeing anything jumping out at me that would be causing you issues. Maybe try another brand of contactor? Is it a name brand one or a chinese import?
mrdoctorm
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Re: Frying contactor

Post by mrdoctorm »

I guess another conductor brand could be my next step. The ones I got were from ebrewsupply. Everything else I've gotten from them has been good.
mrdoctorm
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Re: Frying contactor

Post by mrdoctorm »

So does anyone have a recommendation for where i could buy a different 240v 40A contactor with 120 coil? Preferably din mounted.
BrunDog
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Re: Frying contactor

Post by BrunDog »

Taking some stabs at your schematic in general...

1. Is the ground tied to the breaker? I see a three conductor input, but with both legs and a neutral it should carry a ground back to the panel as well. You show it separate.
2. Get rid of that silly PJ resistor/GFI fault design. Purposely tripping the GFI is bad bad bad.
3. You have 15A breakers which then feed 5A fuses? This makes no sense to me.
4. Not sure why you are using multiple poles of the switches to power an indicator light. You can have that contact close and not the one next to it (or vice versa). The LED's should be directly tied to the circuits that are powered, IMO.

5. BUT the main contactor wiring looks OK. I assume 9 is the a key switch? I would make sure the other side of that is wired to the neutral bus, not Leg 1. When the switch is on, measure the voltage across the contactor coil terminals. Check you are not getting 240V there. Would not overcurrent the 40A breaker, but would certainly overheat the contactor coil.

Another comment is... does this contactor NOT heat up when there is no current drawn across it (as inferred in your post). Will it hold for hours without the elements powered on, then suddenly get hot when they are powered on? If so, make sure your terminals are properly crimped, clean (not oxidized) and properly connected to the contactor. Again, measure the voltage (and current) powering the coil. Also make sure that both elements are somehow not on. SSRs fail all the time. I had one that partially failed and put out 7A into an element of a possible 25A. I know the contactors there should be in an OR mode, but you need to confirm. The LEDs there could tell you when the elements are plugged in, but unplugging the elements is the only way to confirm.

-BD
clearwaterbrewer
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Re: Frying contactor

Post by clearwaterbrewer »

I think we need a picture or two of your contactor wiring...

edit - reason: my suspicion is that you are putting too much voltage to the contactor coil... (either not really a 110v coil or not wired for 110V)
mrdoctorm
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Re: Frying contactor

Post by mrdoctorm »

Thank you BrunDog and clearwaterbrewer for your responses.

to answer your questions BrunDog
1. the ground does go back to the breaker. My drawing shows it wrong and I'll have to correct that.
2. I agree it is bad, but is it worse than someone being shocked? I figure it is a LAST case emergency. I suppose I could replace it with a NC locking mushroom button in line with the key
3. Very valid question to which I have no good answer.
4. The switches are physically connected so I can't have one close and not the one next to it. It is this switch (http://www.ebrewsupply.com/shop/indicat ... witch.html) with extra contactors screwed in behind them. Maybe I just didn't use standard drawing icons to represent them properly.
5. yes 9 is a key. It does go to the neutral bus.
I've been busy with life and have the new contactor but haven't installed it yet. so I haven't been able to do any of the voltage measuring. I'll let you know how those turn out when I run it again.

Clearwaterbrewer, I tried taking some pictured but there is no way you could trace the wires through the rats nest I put together. (I make it sound worse than it is, but I proudly showed it to a friend that professionally does wiring and he put me in my place). I did verify all the wires land where I show in my diagram. And like I mentioned above I'll take some more measurements once I get the new contactor in place.

Thanks again
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