MCQOPTIONS
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MCQOPTIONS
This section includes 249 Mcqs, each offering curated multiple-choice questions to sharpen your Power Systems knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
If time of operation of a relay for unity TMS is 10 secs, then time of operation for 0.5 TMS will be _______ secs |
| A. | 1 |
| B. | 3 |
| C. | 5 |
| D. | 7 |
| Answer» D. 7 | |
| 102. |
If a 100V/10V, 50 VA transformer is converted to 100/110V auto transformer, then rating of the auto transformer is _______ VA |
| A. | 5.50 |
| B. | 55.0 |
| C. | 0.55 |
| D. | 550 |
| Answer» E. | |
| 103. |
A transformer rated for 500 kVA. 11 kv/0.4 kV has an impedance at 10% and is connected to an infinite bus. The fault level of the transformer is ___________ kVA |
| A. | 0.5 |
| B. | 5000 |
| C. | 5.000 |
| D. | 0.005 |
| Answer» C. 5.000 | |
| 104. |
A 100/5 A bar primary current transformer supplies an O/C relay set at 25% pick up and it has a burden at 5 VA. The secondary voltage is _________V |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» B. 2 | |
| 105. |
If the inductance and capacitance of a system are 1 H and 0 01 F respectively and the instantaneous value of current interrupted is 10 amps. The value of shunt resistance across the breaker for critical damping is ________ k |
| A. | 0.5 |
| B. | 0.05 |
| C. | 5 |
| D. | 5.05 |
| Answer» D. 5.05 | |
| 106. |
A nuclear power station of 500 MW capacity is located at 300 km away from a load center. Select the most suitable power evacuation transmission configuration among the following options |
| A. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/Q-24A.jpg"> |
| B. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/Q-25B.jpg"> |
| C. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/Q-25C.jpg"> |
| D. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/Q-25D.jpg"> |
| Answer» B. <img src="http://images.interviewmania.com/wp-content/uploads/2019/12/Q-25B.jpg"> | |
| 107. |
The ratio of reset to pick up current for an induction cup relay is approximately _________ |
| A. | 9.90 |
| B. | 0.99 |
| C. | 99 |
| D. | 0.099 |
| Answer» C. 99 | |
| 108. |
The impedance value of generator is 0.2 p.u. on a base value of 11 kV, 50 MVA. The impedance value for a base value of 22 kV, 150 MVA is _______ p.u. |
| A. | 5 p.u |
| B. | 1.5 p.u |
| C. | 0.15 p.u |
| D. | 15 p.u |
| Answer» D. 15 p.u | |
| 109. |
The plug setting of a negative sequence relay is 0.2 A. The current transformer ratio is 5: 1. The minimum value of line to line fault current for the operation of the relay is _______ A |
| A. | 1732 |
| B. | 1.732 |
| C. | 17.32 |
| D. | 173.2 |
| Answer» C. 17.32 | |
| 110. |
A 100/5 A bar primary current transformer supplies an O/C relay set at 25% pick up and it has a burden of 5 VA. The secondary voltage i s __________V |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» E. | |
| 111. |
In a 400 kV power network, 360 kV is recorded at 400 kV bus. The reactive power absorbed by a shunt reactor for 50 MVAr, 400 kV connected at the bus is _________ MVAr |
| A. | 40.05 |
| B. | 4005 |
| C. | 40.5 |
| D. | 4.5 |
| Answer» D. 4.5 | |
| 112. |
The positive sequence current for a L-L fault of a 2 kV system is 1400 A, and corresponding current for a L-L-G fault is 2220 A. The zero sequence impedance of the system is ________ |
| A. | 5.275 |
| B. | 52.75 |
| C. | 5275 |
| D. | 0.5275 |
| Answer» E. | |
| 113. |
If the fault current is 2000 A, the relay setting is 50% and CT ratio is 400: 5, then plug setting multiplier will be _________ A |
| A. | 10 |
| B. | .010 |
| C. | 1.0 |
| D. | .001 |
| Answer» B. .010 | |
| 114. |
An industrial consumer has a daily load pattern of 2000 kW, 0.8 lag for 12 Hrs. and 1000 kW UPF for 12 Hrs. The load factor is ________ |
| A. | 0.75 |
| B. | 75 |
| C. | 7.5 |
| D. | 0.0075 |
| Answer» B. 75 | |
| 115. |
What is the overall diameter of a single core cable when its working on a three phase 264 kV system? The maximum permissible stress in the dieletric is not to exceed 20 kV/mm is ________ mm |
| A. | 21.4 mm |
| B. | 214 mm |
| C. | 2.14 mm |
| D. | .214 mm |
| Answer» B. 214 mm | |
| 116. |
A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short circuit line current of ___________ A |
| A. | 0.150 |
| B. | 15.0 |
| C. | 150 |
| D. | 1.50 |
| Answer» D. 1.50 | |
| 117. |
A 60 kV (rms) single core metal sheathed cable is to be graded by means of a metallic intersheath. The safe electric stress of the insutating material is 6 kV/mm (rms). The overal diameter of the intersheath is ________ mm |
| A. | 2.0 mm |
| B. | 20 mm |
| C. | 0.020 mm |
| D. | 200 mm |
| Answer» C. 0.020 mm | |
| 118. |
To increase the visual critical voltage of cporona for an overhead line, one solid phase-conductor is replaced by a bundle of four smaller conductors per phase, having an aggregate cross-sectional area equal to that of the solid conductor. If the radius of the solid conductor is 40 mm, then the radius of each of the bundle conductors would be _______ mm |
| A. | 2.0 mm. |
| B. | 0.020 mm. |
| C. | 0.20 mm. |
| D. | 20 mm. |
| Answer» E. | |
| 119. |
A 220 kV, 20 km long, 3-phase transmission line has the following A, B, C, D constants: |
| A. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>10</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">3</span></td></tr></table> |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>3</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">11</span></td></tr></table> |
| C. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>11</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">3</span></td></tr></table> |
| D. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>9</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td></tr></table> |
| Answer» D. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>9</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">2</span></td></tr></table> | |
| 120. |
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 power factor to unity. The capacitance per-phase of the capacitor in microfarads is __________ |
| A. | 1216 |
| B. | 1316 |
| C. | 1612 |
| D. | 1613 |
| Answer» C. 1612 | |
| 121. |
The per cent age resistance and per cent age react ance of a 10 kVA, 400 V/200 V, 3-phase transformer are 2% and 10% respectively. If the const ant losses in t he machine are 1%, the maximum possible percentage efficiency of the transformer is __________ |
| A. | 96.85 |
| B. | 9.685 |
| C. | 968.5 |
| D. | 0.9685 |
| Answer» B. 9.685 | |
| 122. |
Plug setting of a relay can be altered by varying |
| A. | number of ampere-turns |
| B. | air gap of magnetic path |
| C. | adjustable back up stop |
| D. | none of these |
| Answer» B. air gap of magnetic path | |
| 123. |
For an existing ac transmission line, the string efficiency is 80%, if dc voltage is supplied for the same set up, the string efficiency will be ______% |
| A. | 70 |
| B. | 80 |
| C. | 90 |
| D. | 100 |
| Answer» E. | |
| 124. |
If a line is 100% series compensated, it may result into series resonance at power frequency of _______ Hz |
| A. | 5.0 |
| B. | 0.5 |
| C. | 50 |
| D. | 0.05 |
| Answer» D. 0.05 | |
| 125. |
An IDMT over current relay has a current setting of 15% and has a time multiplier setting of 0.5. The relay is connected in the circuit through a CT having 500: 5. The time of operation of the relay if the circuit carries a fault current of 6000 A is ________ sec |
| A. | 157.5 sec. |
| B. | 15.75 sec. |
| C. | 1.575 sec. |
| D. | 1575 sec. |
| Answer» D. 1575 sec. | |
| 126. |
The surge impedance of a 400 km long overhead transmission line is 400 ohms. For a 200 km length of the same line, the impedance will be _______ |
| A. | 0.4 |
| B. | 400 |
| C. | 0.04 |
| D. | 40 |
| Answer» C. 0.04 | |
| 127. |
A long distance overhead transmission line of 220 kV rating is to be protected against faults between phase and ground. The fault resistance including that of the ground is found to vary over a wide range. Which of the following types and relays will give the best performance under the situation indicated above? |
| A. | Overcurrent relay |
| B. | Differential relay with percentage bias |
| C. | Reactance type distance relay |
| D. | Impedance type distance relay |
| Answer» D. Impedance type distance relay | |
| 128. |
A transformer is rated at 11 kV/0.4 kV, 500 kVa, 5% r eact ance. What is the short circuit M VA of the transformer when connected to an infinite bus? |
| A. | 20 MVA |
| B. | 10 MVA |
| C. | 15 MVA |
| D. | 5 MVA |
| Answer» C. 15 MVA | |
| 129. |
A single core lead covered cable is to be designed for 132 kV to earth. Its conductor radius is 20 mm and its insulating material A, B and C have relative per mittivities 5, 4 and 3 respectively and corresponding maximum permissible stresses of 3.6, 2.4 and 2.0 kV/mm (rms) respectively. The minimum diameter of the lead steath will be _______ mm |
| A. | 173.78 mm |
| B. | 1738 mm |
| C. | 1.7378 mm |
| D. | 173.8 mm |
| Answer» B. 1738 mm | |
| 130. |
Steady-state stability limit is |
| A. | greater thantranient stability limit |
| B. | equal to transient stability limit |
| C. | less than the transient stability limit |
| D. | none of these |
| Answer» B. equal to transient stability limit | |
| 131. |
For enhancing the power transmission in a long EH V transmission line, the most preferred method is to connect a |
| A. | series inductive compensator in the line |
| B. | shunt inductive compensator at the receiving end |
| C. | series capacitive compensator in the line |
| D. | shunt capacitive compensator at the sending end |
| Answer» D. shunt capacitive compensator at the sending end | |
| 132. |
For a long uncompensated line the limit to the line loading is governed by |
| A. | thermal limit |
| B. | voltage drop |
| C. | stability limit |
| D. | corona loss |
| Answer» D. corona loss | |
| 133. |
A 3 load of 750 kW at 400 V, 50 Hz, operates at a power factor of 0.7 lagging. What is the capacitance per phase of a mesh connected capacitor bank to improve the power factor to 0.95 lagging? |
| A. | 3040 F |
| B. | 2500 F |
| C. | 3438 F |
| D. | 2789 F |
| Answer» D. 2789 F | |
| 134. |
A single circuit 50 Hz, 3 transmission line has the following parameters per km. |
| A. | 0.926% |
| B. | 9.26% |
| C. | 92.6% |
| D. | 926% |
| Answer» D. 926% | |
| 135. |
A single phase load of 200 kVA, is delivered at 2500 V over a tranmissi on line having a R = 1.4 , X = 0.8 . What is the voltage at the sending end, when the power factor of the load is 0.8 lagging? |
| A. | 2.627 kV |
| B. | 2.069 kV |
| C. | 2.840 kV |
| D. | 3.54 kV |
| Answer» B. 2.069 kV | |
| 136. |
A three phase synchronous generator delivers 10 mvA, at a voltage of 10.5 kV. The line impedance is 5 . What is the voltage drop in the line in per unit and in volts ? Use the reference base as 12 mVA at 11 kV. |
| A. | 549.36A, 1.25 kV |
| B. | 539.46A, 2.81 kV |
| C. | 549.36A, 2746.8 kV |
| D. | 549.36A, 2.0 kV |
| Answer» D. 549.36A, 2.0 kV | |
| 137. |
In the above question, the maximum energy that could be produced daily is |
| A. | 500 MWh/day |
| B. | 360 MWh/day |
| C. | 600 MWh/day |
| D. | 720 MWh/day |
| Answer» B. 360 MWh/day | |
| 138. |
For equilateral spacing of conductors of an untrasposed 3-phase line, we have |
| A. | bal anced receiving end voltage and no communication interference |
| B. | unbalanced receiving end volt age and no communication interference |
| C. | balanced receiving end voltage and communication interference |
| D. | unbal anced receiving end voltage and communication interference. |
| Answer» D. unbal anced receiving end voltage and communication interference. | |
| 139. |
Which one of the following statements is not correct for the use of bundled conduct or sin transmission lines? |
| A. | Control of voltage gradient |
| B. | Reduction in corona loss |
| C. | Reduction in radio interference |
| D. | Increase in interference with communication lines |
| Answer» E. | |
| 140. |
If fault current is 2000 amps, the relay setting 50% and C.T. ratio is 400/5, then plug setting multiplier will be |
| A. | 25 amps |
| B. | 15 amps |
| C. | 50 amps |
| D. | none of these |
| Answer» E. | |
| 141. |
A generating station has a maximum demand of 20 mW, load factor of 60%, a plant capacity factor of 50% and a plant use factor of 72%. What is the reserve capacity of the plant, if the plant, while running as per schedule, were fully loaded? |
| A. | 10 MW |
| B. | 15 MW |
| C. | 2 MW |
| D. | 5 MW |
| Answer» E. | |
| 142. |
A power station supplies the peak load of 50 MW, 40 MW and 70 MW to three localities. The annual load factor is 0.50 p.u. and the diversity factor of the load at the station is 1.55. The maximum demand on the station and average load respectively will be |
| A. | 120 MW, 60.8 |
| B. | 90 MW, 50.6 |
| C. | 103.2 MW, 51.61 |
| D. | 100 MW, 0.51 |
| Answer» D. 100 MW, 0.51 | |
| 143. |
In a DC transmission line |
| A. | it is necessary for the sending end and receiving end to be operated in synchronism |
| B. | the effects of inductive and capacitive reactances are greater than in an AC transmission line of the same rating. |
| C. | there are no effects due to inductive and capacitive reactances. |
| D. | power transfer capability is limited by stability considerations. |
| Answer» D. power transfer capability is limited by stability considerations. | |
| 144. |
The yearly load duration curve of a power plant is a straight line. The maximum load is 750 MW and the minimum load is 600 MW. The capacity of the plant is 900 MW. What is the capacity factor and utilization factor? |
| A. | 0.56, 0.80 |
| B. | 0.75, 0.83 |
| C. | 0.78, 0.9 |
| D. | 0.80, 0.83 |
| Answer» C. 0.78, 0.9 | |
| 145. |
What is the utilization factor of a power station which supplies the following loads ? |
| A. | 1.60 |
| B. | 1.32 |
| C. | 1.00 |
| D. | 2.56 |
| Answer» C. 1.00 | |
| 146. |
For a single phase overhead line having solid copper conductors of diameter 1 cm, spaced 60 cm between centers, the inductance in mH/km is |
| A. | 0.05 + 0.2 ln 60 |
| B. | 0.2 ln 60 |
| C. | 0.05 + 0.2 ln (60/0.5) |
| D. | 0.2 ln (60/0.5) |
| Answer» D. 0.2 ln (60/0.5) | |
| 147. |
What is the capacitance of neutral/km of a 1 phase line composed of number 2 single strand conductor radius is 0.328 cm, spaced 3 m apart and 7.5 m above the ground ? Neglecting earth effect. |
| A. | 0.817 F/km |
| B. | 0.00817 F/km |
| C. | 0.0212 F/km |
| D. | 0.516 F/km |
| Answer» C. 0.0212 F/km | |
| 148. |
When bundle conductors are used in place of single conduct or s, the effective inductance and capacitance will respectively |
| A. | increase and decrease |
| B. | decrease and increase |
| C. | decrease and remain unaffected |
| D. | remain unaffected and increase |
| Answer» C. decrease and remain unaffected | |
| 149. |
A medium line with parameters A, B, C, D is extended by connecting a short line of impedance Z in series. The over all ABCD par ameters of the series combination will be |
| A. | A, AZ, C + D/Z, D |
| B. | A, AZ + B, C, CZ + D |
| C. | A + BZ, B, C + DZ, D |
| D. | AZ, B, C/Z, D |
| Answer» C. A + BZ, B, C + DZ, D | |
| 150. |
A single phase transmisson line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is |
| A. | unity |
| B. | 0.8 lagging |
| C. | 0.8 leading |
| D. | 0.6 lagging |
| Answer» E. | |