PROTECTION AND SWITCHGEAR - QUESTIONS AND ANSWERS

1.What is resistance switching?

It is the method of connecting a resistance in parallel with the contact space(arc). The resistance reduces the restriking voltage frequency and it diverts part of the arc current. It assists the circuit breaker in interrupting the magnetizing current and capacity current.

2. What do you mean by current chopping?

When interrupting low inductive currents such as magnetizing currents of the transformer, shunt reactor, the rapid deionization of the contact space and blast effect may cause the current to be interrupted before the natural current zero. This phenomenon of interruption of the current before its natural zero is called current chopping.

3. What are the methods of capacitive switching?

• Opening of single capacitor bank • Closing of one capacitor bank against another