UNIT II

Fundamentals of Arc Interruption

Q1) What is an arc? Explain Arc Interruption Methods.

Q2) Discuss the recovery rate theory and energy balance theory of arc interruption in a circuit breaker.

Q3) Explain terms:  i) Restriking voltage    ii) Recovery voltage      iii) RRRV

Q4) Derive expressions for restriking voltage and RRRV.

Q5) What is resistance switching?

Q6) Explain the phenomenon of current chopping in a circuit breaker. What measures are taken to reduce it?

Q7) Discuss the problem associated with the interruption of

        (i) Low inductive current                          (ii) Capacitive current

Q8) Write a note on current chopping.

Q9) Mention the different methods of high resistance arc interruption.

Q10) A 3-phase alternator has the line voltage of 11kV. The generator is connected to a circuit breaker. The inductive reactance upto the circuit breaker is 5Ω/phase. The distributed capacitance upto circuit breaker between phase and neutral is 0.001 μF. Determine peak restriking voltage across the CB, frequency of restriking voltage, average rate of restriking voltage upto peak restriking voltage, maximum RRRV.