Better 50 Amp Relay

[Bradley]

Does anyone know of a better relay option for the 50amp Struthers-Dunn?  Mine started failing after about a year in service, due to stuck contacts.  I've been giving it a wack and a reboot to keep it going in the short term, but it's time to fix it right.  I don't really want to replace junk with the same junk.  It's never had more then 27 amps drawn through it. 

[Chris]

The Struthers Dunn 50 is a premium UL listed part with upgraded contacts it should last a lifetime especially with the J1772 soft start and the soft stop from the latch and button on the handle. The press of the button requires the EV to stop drawing current within 100ms. The only way a relay would weld it's contacts is if the relay was frequently opened under load. This would only happen with a panic stops due to GFI fault, a broken latch that allows unplugging before the button triggers or a broken button.

If your relay has failed with only a year in service we would highly recommend investigation into why the relays would be opening under load.

Chris

[Adam Sharp]

It could also be contamination of the mechanism or failure of the relay to keep the contacts clean.  Under current can make the contacts fail to clean themselves and require a small amount of arching to perform this 'clean' function.  And depending on the environment, may become sticky.  But most likely the mechanical 'sticking' of the arm/plunger is occurring.  Again due to contamination, but of the mechanism rather than the contacts themselves.

With all connections removed and the relay on the bench, carefully remove the cover, operate the mechanism by pushing the plunger down firmly and identify what is 'sticking'.  Then you can make a better judgement.  The plunger can be lubricated with a small amount of high voltage silicon grease.  Or the contact surfaces can be cleaned with a thin file (they are a very hard metal, so don't worry about surface damage with a hand tool - no power tools!!).

As Chris has suggested, the reason is vitally important in understanding the failure, before a replacement is sort or a solution to prevent contaminations entering the relay itself.  Dry dusty environments or areas with high salt contents (coastal areas) are often an issue for relays.  If a replacement is the only solution, maybe a contactor with a 'parallel' movement on the contacts and plunger maybe a better solution, but only once the failure is understood.

Adam.

[Nuno Casanova Leitao]

Hello all

This discussion waked me up to the fact I have the GFI Self Test, and other 2 tests set to disable. This is so almost from the beginning, more than 2 years ago.

https://photos.app.goo.gl/nWEq2EFFLhcC5zkL9

When I login to the charger I see the above screen regarding the tests.

6 errors "no ground" 
What does this exactly mean? the earthing is gone?

11 errors "stuck contacts"

I have a quite heavy contactor that never had more than 16A on it. (it's the rating of my cable.) It's a Telemecanique LC1 D40, rated for 40A.
Although it was installed new, it was on the shelf probably more than 10 years, and because of this, I got it for free.

Regarding the stuck contact faults, my question is, how does the Evse detects a stuck contact?
I just want to understand if this is really a stuck contact or if this can be a wrong detection.

https://photos.app.goo.gl/2YqHCGnD4gDvxWK67
on the 30 second mark of this above video I press the button on the plug, and we see the current drops to 0, as it should.

What am I missing here? should I change the relay/contactor?

Sorry the hijack, but it's somewhat related.

Best regards and thank you
Nuno