Paralleled gensets and fault current

[Elect117]

I agree that the contacts of the set mounted breaker will not see more than 2 generator's maximum worth of fault current, but if the fault happens on the line or load side of one of the set mounted breaker, the breaker terminations will see 3 generators worth of fault current and needs to be braced for such. The standards for breakers generally do not differentiate the AIC rating of a breaker and the withstand rating of a breaker mounting / terminations, so you would still fail at 100kA.

You mean if the fault is breaker terminal to breaker terminal (on the same side of the breaker, either line or load)? Are the magnetic force effects from the currents going into the terminal from the two different sides additive or subtractive?

Cheers, Wayne

Wouldn't that mean their was a catastrophic failure of the breaker anyway? I wouldn't expect it to operate as intended right?

 

[ron]

Wouldn't that mean their was a catastrophic failure of the breaker anyway? I wouldn't expect it to operate as intended right?

The SCCR means it can accommodate that amount of current without catastrophic failure.