Power systems Objective Type Questions Gate Preparation Power generations

1.An industrial consumer has a daily load pattern of 2000kW,0.8 lag for 12 hrs and 1000 kW UPF for 12 hrs. The load factor is
a)0.5 b)0.75
c)0.6 d)2.0
Answer:0.6

2.What is the maximum value of a load which consumes 500 kWh per day at a load factor of 0.40. if the consumer increases the load factor of 0.50 without increasing the maximum demand?
a)52.08kW b)50.8kW
c)4.5kW d)60Kw
Answer:52.08kW

3.A consumer consumes 600 kWh per day at a load factor of 0.40. if the consumer increases the load factor of 0.70 without increasing the maximum demand, what the consumption of energy in kWh
a)950kWh b)1000kWh
c)1050kWh d)1100kWh
Answer:1050kWh

4.the yearly load duration curve of a power plant is a straight line. The maximum load is 750 MW and the minimum load is 600MW.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)0.75,0.83
Answer:0.75,0.83,

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5.What is the utilization factor of a power station which supplies the following loads?
Load A: motor load of 200 kW between 10 am to 7 pm
Load B: lighting load of 100kW between 7pm to 11pm
Load C: pumping load of 110 kW between 3pm to 10am
a)1.60 b)1.32
c)1.00 d)2.56
Answer:1.32

6.A power station supplies the peak load of 50MW,40MW, and 70MW 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)120MW,60.8 b)90MW,50.6
c)103.2MW,51.61 d)100MW,0.51
Answer:103.2MW,51.61

7.A generating station has a maximum demand is 50 MW, a load factor of 60%, a plant capacity factor of 45% and if the plant while running as per schedule, were fully loaded. The daily energy produced will be
a)400MW b)720MW
c)500MW d)600MW
Answer:720MW
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More: Electrical Machines Objective Type Questions For Gate Preparation-2

8.A generating station has a maximum demand of 20 MW, the 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)10MW b)15MW
c)2MW d)5MW
Answer:5MW

9.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:500MWh/day

10.A 100 km transmission line is designed for a nominal voltage of 132 kV and consists of one conductor per phase. The line reactance is 0.726 ohm/km.the static transmission capacity of the line, in megawatts, would be
a)132 b)240
c)416 d)720
Answer:416

11.The per unit impedance of a circuit element is 0.15. if the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be
a)0.075 b)0.15
c)0.30 d)0.600
Answer:0.30

12.The conductor of a 10 km long, single phase, two wire line are separated by a distance of 1.5 mother diameter of each conductor is 1 cm.if the conductors are of copper, the inductance of the circuit is
a)50.0 mH b)45.3 mH
c)23.8 mH d)19.6 mH
Answer:23.8 mH

13.A 100 km long transmission line is loaded at 110kV.if the loss of line is 5 MW and the load is 150MVA, the resistance of the line is
a)8.06 ohms per phase
b)0.806 ohms per phase
c)0.0806 ohms per phase
d)80.6 ohms per phase
Answer:8.06 ohms per phase

14.A 3-phase,11kV,50Hz,200kW, 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 micro-farads is
a)3.948 b)1.316
c)0.439 d)11.844
Answer:1.316

15.Which one of the following statements is not correct for the use of bundled conductors in transmission lines?
a) control of voltage gradient
b) reduction in corona loss
c)reduction in ratio interference
d)increase in interference with communication lines
Answer: increase in interference with communication lines

16.A single phase transmission line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 The sending end power factor is
a) unity b)0.8 lagging
c)0.8 leading d)0.6 lagging
Answer: 0.6 lagging

17.A medium line with parameters A, B, C, D is extended by connecting a short line of impedance z in series. The overall ABCD parameters of the series combination will be
a) A, AZ, C+D/Z, D
b) A, AZ+B, C+DZ, D
c)A+BZ, B, C+DZ, D
d)AZ, B, C/Z, D
Answer: A, AZ+B, C+DZ, D

18.When bundle conductors are used in place of single conductors, 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: decrease and increase

19.For an exciting ac transmission line, the string efficiency is 80%, if dc voltage is supplied for the same set up, the string efficiency will be
a) <80%
b)80%
c)90%
d)100%
Answer:100%

20.For a 500 Hz frequency excitation, a 50km long power line will be modelled as
a) short time
b) medium time
c)long time
d)data insufficiency for decision
Answer: long time

21.What is the sag for a span of 400m, if the ultimate tensile strength of conductor is 6000 kef, and the weight of conductor is 550kgf/km? factor of safety is 2.
a)1.016 m b)2.40 m
c)3.6 m d)4.2 m
Answer:3.6 m
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22.A transmission line conductor at a river crossing is supported from two towers at height of 30m and 90m above water level. The horizontal distance between towers is 270m, if tension in the conductor is 1800 kg and conductor weight 1 kg/what is the clearance between conductor and the water at a point midway between the towers?
a)79.50 m b)54.94 m
c)60 m d)51.4 m
Answer:54.94 m

23.An overhead transmission line has a span of 240 m between level supports. What is the maximum sag if conductor weight 727 kg/km and has a breaking strength of 6880 kg?allow the factor of safety of 2 and neglect wind and ice loading
a)1.52 m b)1.6 m
c)0.75 m d)1.25 m
Answer:1.52 m

24.A conductors composed of seven identical copper strands, each having a radius rather self GMD of the conductors will be
a)2.177 r b)2.645 r
c)2.141 r d)1.21 r
Answer:2.177 r
STEADY-STATE PERFORMANCE OF OVERHEAD TRANSMISSION LINES AND CABLES AND SURGE PROPAGATION

25.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 dielectric is not to exceed 20 kV/mm.
a)21.4 mm b)24.4 mm
c)22.4 mm d)28.2 mm
Answer:21.4 mm