RCD Test Timings.

[kai]

On a Wylex 60amp RCD, 30MA trip.
The following results were obtained.
Earth Loop impedance of circuit was 0.27 ohms on a PME system.
POS cycle trip time = 11 milliseconds, at 1 and 5 times trip current.
NEG cycle trip time = 22 milliseconds, at 1 and 5 times trip current.
Is it normal for an RCD to have such differing trip times?

 

[industryspark]

would expect the rcd to trip faster for 1 times trip current than the 5 times trip current! you have them as the same for both.

the pos and neg cycles are often different, just record the highest and make sure its within allowance and your ok.

 

[Spark123]

or t'other way round, faster at 5I than at I

 

[industryspark]

cheers for pointing out my deliberate mistake spark 123

apologys for the blonde moment folks! still recovering from last nights excesses!

 

[kai]

Incidentally the circuit being tested was the Cooker Control Panel Socket, on a B20 breaker (cause it only feeds a 3kW Oven, in place of the former cooker).

 

[securespark]

I got the following information from MEM, following a test report on some RCD's we had sent back for testing.

Ideally, for a perfect rms profile, there should be a 10ms difference between tests on + and -ve cycle.

If anyone wants to see a copy, please e-mail me.