ABOUT CAPACITOR IN SHORT CIRCUIT???

[nostromo332003]

HI

I had a question about capacitor.
In a short circuit, the capacitor contribution with current to the fault???

I said not but really a dont know exactly??

regards

 

[buzzp]

If the capacitor is charged at the time of the fault, it will contribute to a fault. The duration depends on the cap size but I think, in general, it is negligible.

If your talking about a capacitor bank or something similar, it should be considered. Especially if the breaker, or whatever is going to break the fault, is before the capacitor circuit. Then the caps can continue to feed the fault until all energy is dissipated out of the caps (could happen real quick or not depending on the impedance).

 

[dpc]

It's generally ignored. On a typical power system, fault current is highly inductive so capacitive discharge current would be 180 degrees out of phase with the other fault current sources.

It can be an issue in certain circumstances.

I'd recommend Conrad St. Pierre's book "A Practical Guide to Short Circuit Calculations" if you want an in-depth look at the topic.

 

[cuky2000]

Capacitors may produce only high transient current of short duration at frequency much larger than the regular sources.

Therefore, capacitors do not make significant contributions to the overall short circuit in an AC power system even if the capacitor is charged.

SC contribution comes exclusively from rotating machineries (motors and generators).

For additional reference in this topic consult “Sources of fault current” IEEE Std 141 - Chapter 4.