RCD Question

[dtombs]

Hi,

I know this might sound a simple question to answer in an exam but in one of the 2391 written papers one of the questions asks "what are the current ratings to be used for a 30mA RCD test". I answered 15mA (half times), 30mA (one times) and 150mA (five times). Am I correct in saying this as it has been bugging me a bit.

Thanks.
Dan

 

[wallyanker]

sounds good to me. Don't forget that when testing at these ratings, you do all tests at 0 degrees and at 180 degrees and record the highest reading

 

[solo2771]

sonds like the right answer to me.
Paul

 

[GrannySmiff]

I agree that is correct as far as I can see, also I hope thats what questions are like for the 2391.

 

[Phil]

have you taken the exam yet or was it a past paper you are doing ?

 

[solo2771]

i found its not the questions its the wording that can confuse, questions were easy once you work out what they are asking.

 

[dtombs]

That was a question from one of the past papers I took (about a year ago). When you say 0 degrees and 180 degrees, is that refering to the sine wave formation of the AC supply current?

 

[wallyanker]

Yes. Test the RCD at 0 and 180 to make sure it will operate at both positive and negative sides of the cycle.

 

[rinkerdink]

Would have stated the expected correct result too just to be sure i.e no trip at half rating and within 30ms for rating and 5 times

 

[peteludman]

5 times is 40ms

 

[Guest123]

Hi,

I know this might sound a simple question to answer in an exam but in one of the 2391 written papers one of the questions asks "what are the current ratings to be used for a 30mA RCD test". I answered 15mA (half times), 30mA (one times) and 150mA (five times). Am I correct in saying this as it has been bugging me a bit.

Thanks.
Dan

Sounds bang on to me.