The current zero interruption, in oil and air blast circuit breakers, is achieved by_______________?

A. neutral wire
B. negative of D.C. circuit
C. positive of D.C. circuit
D. phase dine

A. protect the line
B. open the circuit
C. protect the appliance
D. prevent excessive currents
E. none of the above

A. transposition of the power line
B. transposition of the communication line
C. both (A) and (B)
D. increasing the distance between the conductors

A. thermocouple
B. electronic and bimetallic
C. both (A) and (B)
D. none of the above

A. mechanical vibration
B. insulation failure
C. loose connection
D. impulse voltage

A. recovery
B. surge
C. operating
D. arc
E. none of the above