Transmission Line Objective Type Questions and answers

26.  The positive sequence current of a transmission line is

   A. Always zero

   B. One third of negative sequence current

   C. Equal to negative sequence current

   D. three times the negative sequence current

27.  When a fault occurs in a high-voltage transmission line, first the

   A. Circuit breaker operates then the relay

   B. Relay operates then the circuit breaker

   C. Relay operates, then successfully the isolator and the circuit breaker

   D. Isolator operates, then successfully the relay and the circuit breaker

28.  Zero sequence impedance of the transmission line is

   A. equal to the positive sequence impedance of the line

   B. About 2.5 to 3 times the positive sequence impedance of the line

   C. Less than positive sequence impedance of the line

   D. none of the above

29.  A transmission line is protected bye

   A. Distance protection

   B. Current graded overcurrent protection

   C. Time graded overcurrent protection

   D. All of the above

30.  Which is the main relay for protecting up to 90% of the transmission line length in the forward direction?

   A. Directional overcurrent relay

   B. Mho relay

   C. Carrier-current protection relay

   D. Impedance relay

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