Rccb & Rcd

[wkyong]

Under what conditions can cause a 3 phases RCCB(residual current circuit breaker) or RCD (residual circuit breaker)trip off?Let say if red phase takes10A ,yellow phase takes 5A & blue phase takes 7A,under this unbalanced current condition will it trips the above breaker?

 

[Bob Scott]

Under what conditions can cause a 3 phases RCCB(residual current circuit breaker) or RCD (residual circuit breaker)trip off?Let say if red phase takes10A ,yellow phase takes 5A & blue phase takes 7A,under this unbalanced current condition will it trips the above breaker?

The phase with the excessive current should trip and also disconnect the other two phases.

 

[Pommie]

I assume the 3 phase breaker will trip if the phase and neutral currents don't add up to zero. I have 3 phase breakers in my house, I can arbitrarily turn on single phase appliances and therefore have very out of balance phase currents, the overall current, including neutral, is however still zero. My recollection is that an out of balance current of 35mA is required to trip an RCD.

I assume there are also breakers that detect out of balance phase currents to protect motors etc.

Mike.

 

[steven7890]

single phase RCCBs with "1P+N" label come into the industries some years ago. Like to know if 1P+N stand for 1 pole + neutral, or 1 phase+ neutral (Wiki did not say this) ? Also does 1P+N type of RCCB has 2 pole (2 set of single pole but mechanically gang together) isolator inside? This is because I see "1P+N" and "2 pole" appear on the same product descriptions of RCCB?

 

[dr pepper]

A 3 phase rcd will only trip if one or more of the currents on the 3 phases increases past the 'breakers ratings, or if the currents on all 3 phases and neutral dont cancel, ie if a current higher than the rcd trip current (30ma, 100ma etc) is comming out of one of the 3 lives and not returning on either one of the other lives or neutral, ie you've got hold of a live and the resultant current is passing through you to ground instead of back to neutral or another live.