Power Plant Engineering Objective Questions

101. Block rate tariff, where energy charge decreases with the increase in energy consumption,

(a) encourages the consumers for more consumption.
(b) discourages the consumers for more consumption.
(c) encourages the consumers to restrict their demands.
(d) encourages the consumers to improve the power factor.

102. The penalty for low power factor is imposed on

(a) residential and commercial consumers.
(b) industrial consumers.
(c) agricultural consumers.
(d) all of the above.

103. Doherty rate tariff is applied to

(a) domestic consumers.
(c) bulk supplies.
(b) medium industrial consumers.
(d) municipal loads.

104. Maximum demand tariff is generally not applied to the domestic consumers owing to their

(a) low maximum demand.
(b) low load factor.
(c) low power factor.
(d) low energy consumption.

105. Low power factor is usually not due to

(a) discharge lamps.
(b) incandescent lamps.
(c) arc lamps.
(d) induction furnaces.

106. The primary reason for low power factor is owing to installation of

(a) synchronous motors.
(b) dc motors.
(c) induction motors.
(d) commutator motors.

107. Low power factor has the drawback(s) of

(a) increased transmission and distribution losses.
(b) poor voltage regulation.
(c) high cost of equipment for a given load.
(d) all of the above.

108. The low power factor of an industrial plant is uneconomical for

(a) electric supply utility only.
(b) owner of the plant only.
(c) both the owner of the plant and the electric supply utility.
(d) either (a) or (b).

109. For a consumer the most economical power factor is usually

(a) 0.25 – 0.5 lagging.
(b) 0.25 – 0.5 leading.
(c) 0.85 – 0.95 lagging.
(d) 0.85 – 0.95 leading.

110. Power factor can be improved by using

(a) static capacitors.
(b) synchronous condensers.
(c) phase advancers.
(d) all of the above.

111. Static capacitors are rated in terms of

(a) kVAR
(b) kW
(c) kVA
(d) kWh

112. For power factor improvement static capacitors have the advantage(s) of

(a) small losses.
(b) easy installation.
(c) low initial cost and little maintenance.
(d) all of the above.

113. For power factor improvement static capacitors have the drawback(s) of

(a) short-service life.
(b) getting damaged by high voltage.
(c) not repairable.
(d) all of the above.

114. For power factor improvement synchronous condensers have the drawback(s) of

(a) comparatively higher maintenance and operating costs.
(b) requirement of auxiliary equipment for their starting.
(c) possibility of falling out of synchronism causing in interruption of supply.
(d) all of the above.

115. Advantages of the improved power factor are

(a) increase in operating efficiency of the power system.
(b) improvement in voltage regulation.
(c) reduction in overall cost per unit.
(d) better utilization of kW capacities of prime movers, transformers, switchgear and the lines.

116. The most suitable location for a power factor improvement device is

(a) near the electrical appliance which is responsible for the poor power factor.
(b) at the receiving end, in case of a transmission line.
(c) at the sending end.
(d) any where in the circuit.
(e) both (a) and (b).

118. An industrial installation has a power factor of 0.8 lagging. It would be economical to improve pf to

(a) unity.
(b) about 0.8 leading.
(c) about 0.95 lagging.
(d) about 0.95 leading.

119. A 3-phase, 11 kV, 50 Hz, 200 kW load has a power factor of 0.8 lag. A delta-connected 3-phase capacitor is used to improve the pf to unity. The capacitance per phase of the capacitor in micro-farads is

(a) 3.948
(b) 1.316
(c) 0.439
(d) 11.844 [GATE E.E. 1999]

120. The most economical limit of power factor correcting is governed by

(a) original power factor.
(b) relative costs of the supply and power factor correction equipment.
(c) both (a) and (b).
(d) none of the above.

121. There is a limit beyond which it is not economical still further to improve the power factor in order to meet the increased demand on the generating station. The maximum value to which the pf can be economically raised entirely depends upon

(a) the cost of the power factor correction equipment.
(b) the cost of the generating plant.
(c) the relative costs of the generating plant and phase advancing plant.
(d) none of the above.

 

• Power Plant Engineering MCQ Part – 1
• Power Plant Engineering MCQ Part – 2
• Power Plant Engineering MCQ Part – 3
• Power Plant Engineering MCQ Part – 4
• Power Plant Engineering MCQ Part – 5

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