358. Phases comparison relaying is
A. used for providing back-up protection to transmission lines
B. immune to the effects of power surges
C. adversely affected by the currents flowing in the protected line due to mutual induction from another nearby circuit
D. adversely affected by the loss of synchronism between sources of generation beyond the ends of the protected line
359. Maloperation of differential protection of transformers due to magnetizing inrush current is prevented by
A. setting the current of the relay higher then the maximum value of inrush current
B. keeping the time-setting long enough for the current to fall to a value below the primary operating current of the relay
C. bypassing the inrush current from the operating coil of the relay
D. filtering the third harmonic content of the inrush current flowing through the operating coil and passing through the restraining coil
360. Incremental fuel costs in Rs/MWh fo a plant consisting of two units are given by dF
A. 200 MW and 700 MW
B. 300 MW and 600 MW
C. 400 MW and 500 MW
D. 500 MW and 400 MW
361. A single-phase full-bridge, voltage source inverter, feeds a pure inductive load L and the inverter input voltage is V. The current through L, with a period of T second, would be a Vs T
A. triangular wave with peak value ?L ? ?2Vs T
B. triangular wave with peak value ?L ? ?4Vs T
C. square wave with peak value ?L ? ?2Vs T
D. pulsed wave with peak value ?L ? ?2
362. Possible faults that may occur on a transmission line are 1 I. 3-phase fault 2. L-L-G fault3. L-L fault4. L-G fault. The decreasing order of serverity of the faults from the stability point of view is
A. 1-2-3-4
B. 1-4-3-2
C. 1-3-2-4
D. 1-3-4-2
363. Consider the following statements :The function of a condenser in a steam power plant is toI. condenser the large volume of steam to water to be used as boiler feed water.2. receive large volume of steam exhausted from the steam turbine. 3. maintain pressure below atmosphere so that maximum heat energy can be extracted from steam.Which of the statements given above are correct?
A. 1 and 2
B. 2 and 3
C. 1 and 3
D. 1, 2 and 3
364. The per unit impedance of a circuit element is 0.15. If the base kV and base MVA are halved, then what will be the new value of the per unit impedance of the circuit element?
A.0.075
B.0.15
C.0.3
D.0.6
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