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26-11-2020, 11:51   #1
Sir Liamalot
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Are Single Module RCBO faster reacting than Double Module?

I'm having issue with nuisance tripping.
2U RCBO works fine 20A 30mA, trip time 28ms
1U RCBO is nuisance tripping 32A, 30mA trip, time 25ms and 8ms with a 180° offset.


I'd rather use the 1U for reasons but it's too sensitive. If I get another will it be the same?


Hager AD920J (2U)
Hager ADA332G (1U)
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26-11-2020, 12:19   #2
2011
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Are these feeding nonlinear loads?
I do not see why the width of the device and nuisance tripping would be related.
In terms of reliability I would consider Schnieder Electric RCBO’s to have the edge on Hager. Schnieder make 1 mod RCBO’s.
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26-11-2020, 12:31   #3
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Synchronising inverters tripping with load transfer feeding the house (test load). So yeah fridge motors and leds.
It does it with purely resistive loads too though. It's something to do with the phase shift.
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26-11-2020, 12:43   #4
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Schnieder make 1 mod RCBO’s.

Acti-9 won't fit unless I put them upside-down...
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26-11-2020, 13:07   #5
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I just ordered a Schneider EZ9D16832
Rebranded GET so I'm not 100% on yer brand confidence.

I'll let you know if it fairs any better. Cheers.
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26-11-2020, 13:57   #6
 
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They should be fairly random the trip times shouldn't they?

Anything over 1/2 I∆N

Are.any of single mod units actual double pole switching?
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26-11-2020, 15:07   #7
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Originally Posted by Sir Liamalot View Post
Synchronising inverters tripping with load transfer feeding the house (test load).
The high frequency PWM switching of inverters can cause nuisance tripping.
This can still be an issue even if the inverters are supplying a resistive load.
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26-11-2020, 16:45   #8
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I swapped the RCBO. Had no problem with the last one. I only use low frequency inverters because they're waaaay better and the HF requirement of B-type RCDs are a waste of money I could just spend on transformer surge capability instead.

Pretty consistent trip times on a digital RCD tester.
Occasionally didn't nuisance trip when the master and slave gensets were harmonising or swapping roles but did most of the time.

There's no fault on the load side.
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26-11-2020, 16:56   #9
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1U RCBOs only interrupt the Live. Single phase TN-S application.

And yes both sets are TN-S but not at the same time.
A double pole would be better in hindsight but I sacrificed the space to metering and a 16A sub.
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26-11-2020, 17:03   #10
 
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1U RCBOs only interrupt the Live. Single phase TN-S application.

And yes both sets are TN-S but not at the same time.
A double pole would be better in hindsight but I sacrificed the space to metering and a 16A sub.
Don't think double pole is strictly required for TN
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26-11-2020, 18:50   #11
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It's not. Would be for floating applications which is a possibility (like right now ironically). I can always put a module inline on a fly lead for this. It's not something I'd elect to do without good reason though. TN-S is my prefered method.
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26-11-2020, 18:58   #12
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Don't think double pole is strictly required for TN
As far as I recall it is a requirement in ROI. I will look later if I get a chance.

Anyway 1 mod wide RCBO's are available with 2 pole switching.
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26-11-2020, 19:03   #13
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Do building regs apply when there's no building or/nor utility involved?

If you do find a reference I'd appreciate the feedback. I like the space-saving so would bias 1Us for this.

I'll have a look for double pole breaking too. Obviously better.
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26-11-2020, 19:44   #14
 
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As far as I recall it is a requirement in ROI. I will look later if I get a chance.

Anyway 1 mod wide RCBO's are available with 2 pole switching.
I haven't checked either but I think they use the phrase

"Neutral reliably at earth potential" for everything TN

Which means only have to switch the phase/ line
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26-11-2020, 19:46   #15
 
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Quote:
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Anyway 1 mod wide RCBO's are available with 2 pole switching.
That's good to know thanks
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