Hi
Here in CH the usage of earth leakage circuit breaker (ELCB) are common. We have two of them to protect the family. Do they have any impact on the measurement results? Where to place a CT? Before or Behind a ELCB?
Thanks for little Explanation!
Best Regards,
Axel
Re: Impackt of a Earth Leakage Circuit Breaker on measurement?
A Residual Current Device (RCD, or previously called an Earth Leakage Circuit Breaker) should have absolutely no effect on current measurements, nor vice versa. You can put the c.t. either side, whichever is convenient.
Re: Impackt of a Earth Leakage Circuit Breaker on measurement?
It will make no difference. The current measured by the CT will be the same either side of the ELCB (called a residual current device (RCD) these days). Look up RCD on Wikipedia for an explanation.
Re: Impackt of a Earth Leakage Circuit Breaker on measurement?
edited
Re: Impackt of a Earth Leakage Circuit Breaker on measurement?
Welcome!
Do you mean ELCB or RCD (residual current device)?
ELCB's which detect a voltage gradient to ground and rely on a single earth path for an installation are no longer favoured in the UK since it was found impossible to rely on a single fault path to earth. (Any parallel earth path is likely to reduce the voltage gradient used by the sensor and permit a dangerous fault current to flow.) For example bonding of water pipes can provide such a parallel path. If you are still using ELCB's then I would strongly recommend that you have your installation checked out for compliance with the current national standard by a qualified electrician. I shall be very surprised if your national standard does not replicate the steps being taken elsewhere towards EU harmonization.
Either way the position of your CT should make no difference either to your family's safety or the measurement.