Main PV breaker tripping

[electro7]

Just yesterday I found out we have a PV main breaker that is tripping. Its a larger resi system, about 20kw so say 83 amps. 200A breaker keeps tripping. I haven't been there yet to investigate, but most likely just a bad breaker, I'll keep you posted.

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[electrofelon]

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So I went there today. Turns out that the bolts that bolt the load side main breaker lugs to the panelboard buss were loose. One was just barely over finger tight, and the other was not even finger tight. This was a Eaton 200A 3R MB load center type panelboard that I installed 18 months ago. Seems like the quality of everything is going right in the toilet. We had a recent thread titled "Sq D quality going down". Well add Eaton to the list of companies that supply garbage now . I guess I'll have to start checked every factory installed fastener now.

 

[ggunn]

So I went there today. Turns out that the bolts that bolt the load side main breaker lugs to the panelboard buss were loose. One was just barely over finger tight, and the other was not even finger tight. This was a Eaton 200A 3R MB load center type panelboard that I installed 18 months ago. Seems like the quality of everything is going right in the toilet. We had a recent thread titled "Sq D quality going down". Well add Eaton to the list of companies that supply garbage now . I guess I'll have to start checked every factory installed fastener now.

So was the heat from the loose connections causing the breaker to trip?

 

[electrofelon]

So was the heat from the loose connections causing the breaker to trip?

yes sir, I am almost certain.

 

[electro7]

Circling back on this.

I am at the site to change out the main breaker and this is what I came across (see photo). Any thoughts on what may have caused this? I have 4- 480V inverters connected to this PV Panelboard and they are the only things connected to it.

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[electrofelon]

Probably a loose connection. Were any of the lugs loose? Might want to also check the lug attachment to the breaker bussing.

 

[electro7]

Probably a loose connection. Were any of the lugs loose? Might want to also check the lug attachment to the breaker bussing.

We checked torque months ago to verify and they were tight. I'm going back to, and hoping, there was a malfunction internal to the breaker. Here is another photo of the back of the breaker.

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[electrofelon]

It might have been hard to tell if it was all chowder, but did the attachment of the lug to the breaker bus seem tight?

 

[electro7]

It might have been hard to tell if it was all chowder, but did the attachment of the lug to the breaker bus seem tight?

On the load side of breaker yes, we checked that. On the line side where these conductors were landed I did not check. They are studs that screw in and out of the bus but have a nut to lock them on. I was unable to losses the lugs with the burnt wires on them so I couldn't check there after the fact

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[electro7]

This is what happened in one of the four inverters amd seems to be connected with the issue. Still trying to figure it out. A power supply for the tigo rapid shutdown transmitter burnt up from L1 and L2. Those supply wires burnt up so much so that it melted and they burnt off of the connections.

These are Canadian Solar branded inverters which I think are Solis manufacturer.

Could harmonic distortion be causing this type of thing to happen?

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