# Relay or charge controller issue?



## zoltan (Mar 15, 2010)

I've seen this issue 2 times in the last month. We have solar powered RTU's and when I show up to troubleshoot the problem I find the 10A 12v Sunsaver solar charge controller burnt up and 1 of the Phoenix 12v relays shorting out + to - on the coil side. The + wire from Sunsaver "battery" terminal seems to be the hot spot on charge controller.

There are Phx 10A push in breakers between the battery box/charge controllers and the RTUs that don't trip.

The working load on the RTU is rarely more than 2A.

We do have the relay modules fail in different ways fairly often, it
will just quit working. Some get cycled constantly and I've heard that they're not designed that kind of duty, any truth to this? Both relay issues are fixed by replacing the white plug in relay module. 

Solar panels are only pushing out around 3A.

I'm thinking that a relay is failing and initiating the sunsaver failure, but have not been able to explain it.

Anyone see problems with this style relay?

https://www.phoenixcontact.com/online/portal/us?uri=pxc-oc-itemdetailid=2966906&library=usen&tab=1


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## MDShunk (Jan 7, 2007)

To the best of my knowledge, the white relay modules for that type of base from most manufacturers are solid state. They require some load to reliably turn on and off completely. You may have better service with the black mechanical relay for those relay bases. You load may be too light from time to time and the relay is "leaking by", so to speak, but not at the full voltage that it would ordinarily pass (thus the failure of the sunsaver).

edit: Do you happen to have an as built print you can post for the whole telemetry cabinet? That might provide a couple more clues. I'm sort of guessing at what the actual arrangement of controls is there.


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## JRaef (Mar 23, 2009)

MDShunk said:


> To the best of my knowledge, the white relay modules for that type of base from most manufacturers are solid state. They require some load to reliably turn on and off completely. You may have better service with the black mechanical relay for those relay bases. You load may be too light from time to time and the relay is "leaking by", so to speak, but not at the full voltage that it would ordinarily pass (thus the failure of the sunsaver).
> 
> edit: Do you happen to have an as built print you can post for the whole telemetry cabinet? That might provide a couple more clues. I'm sort of guessing at what the actual arrangement of controls is there.


According to the data sheet they are real relays, 6A continuous, but the SWITCHING capacity is only 2A at 24VDC (not given for 12VDC but likely the same) and no indication if that’s an inductive or resistive rating other than the DIN spec reference. So yes, it would be very helpful to know what that relay is switching. People are often misled by that “continuous current” rating being higher than the “switching current” rating. What it means is that if you have this relay contact in a circuit that is SWITCHED somewhere ended while the contacts are closed, it can handle 6A though it. But really, it can only be used to SWITCH 2A on its own. 

Where I am heading with that is that you may be using that relay for things it is not rated for, it is welding and therefore can’t turn off whatever it is controlling, then that over burdens the charge controller. Just a SWAG at this point though.


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## Jlarson (Jun 28, 2009)

I don't use those little interface relays for any sort if power switching. I think even a switching rating of 2 amps is generous for those little guys, especially for DC service.


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## zoltan (Mar 15, 2010)

]I don't have a schematic for the whole cabinet but did find one for the relay set up. The far right one is the problem item.


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## zoltan (Mar 15, 2010)

And those 3 relays on the right work together to operate this actuator

https://www.asahi-america.com/images/x-assets/PDF/Datasheet_VDC_Explosion_Proof_Series_92.pdf

The 2 relays on the right operate a 12vdc solenoid that activates a safety shut down valve, so it's rarely energized.

Any idea why the PB 10A breakers don't pop? I believe they are thermal trip breakers.

https://www.alliedelec.com/phoenix-contact-0712259/70207680/?mkwid=szfV6XGiM&pcrid=30980760979&pkw=&pmt=&gclid=CjwKCAjwio3dBRAqEiwAHWsNVSD3cjDjtzgeIS_B9QXIWKg7FUdkco0Ek_zY3xchSoFKKlZOTbS1XhoCaSQQAvD_BwE


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## glen1971 (Oct 10, 2012)

What voltages and currents are you seeing at the Sunsaver?
Open circuit voltage from the array, battery voltage, load voltage, voltage at the array on the sunsaver, with the panels connected.. 
Load, battery and array currents.. On a 10A system, you should be able to put your meter in series, if it is properly fused.. Make sure the load is on, or normal condition while checking this.. I used min/max for a period of time to determine the peak and average load..

Do you have diodes installed at the solenoids? Is the polarity correct at the relay, as they have internal diodes? Is the solenoid 12 vdc? Relays are 12 vdc? It wouldn't be the first time the wrong voltage relay, or component was installed..


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## JRaef (Mar 23, 2009)

“VLV” would make me think solenoid valve or maybe motorized valve. Not likely something those relays can handle.


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## splatz (May 23, 2015)

I have worked with that actuator in the 120v and 24VDC versions. I did the controls with one relay. I had a problem with it and a butterfly valve. The actuator's limit switches have to be very precisely adjusted. The current goes pretty high as the valve gets into the sealed position. 

When the butterfly valve got crusty, the motor would go through the roof because it never quite closed / sealed and you have a locked rotor situation, the valve can't close past the crust, the limit switches never reach the closed position, etc. There was supposed to be protection in the actuator but I never saw it actually work.


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## oliquir (Jan 13, 2011)

those valves would need suppression diodes (or suitable snubber network) on them or else the relays will burn up really fast
i was able to fried 1A plc relay output in few month of cycling just driving 24v octal relays from them without diodes on the relay.


cheapest option would be to replace those fancy relays with regular 10mm 15A ones


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## Jlarson (Jun 28, 2009)

Ah 12v valves. I use a relay like a magnecraft series 92 power relay or similar with added diodes for those.


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## JRaef (Mar 23, 2009)

If you can't / wont replace those little thin TB style Phoenix relays, use them as "interposing relays" to drive another larger capacity relay with say, 15A rated contacts. But definitely put surge suppression on them if you are going to use the same 12V source for those valves. You need to protect everything from the "inductive kickback" (Google that term if you are unfamiliar).


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## zoltan (Mar 15, 2010)

Thanks for all the reply's. I have not been back out to get V & A readings. 
Polarities are correct and all equipment is rated for 12vdc.



JRaef said:


> If you can't / wont replace those little thin TB style Phoenix relays,....


Yeah, there's the rub. We have several Hundred of these RTU's in use. I'm going to run some of these suggestions up the chain of command and see what they want to do. 

Also, again, why isn't the 10A PB breaker tripping when the SS is burning up?


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## MDShunk (Jan 7, 2007)

zoltan said:


> Also, again, why isn't the 10A PB breaker tripping when the SS is burning up?


Probably for the same reason your toaster doesn't trip the breaker every time you make toast.

+1 on using the slimline relay as an interposing relay to bring in the coil of a "real" relay. Those slimline relays are barely pilot duty and no one should have ever used them to switch actual load. I used them a lot, but more or less as "signal conditioning relays". Such as using one voltage to switch another, or using 24 volt from one power supply to switch 24 volt from a different machine's power supply, etc.


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