Applied Electrical Engineering Mid - II, November - 2014

1.The maximum value of power factor can be
  • 1
  • 0.5
  • 0.9
  • None
Answer: A
2.The most economical power factor for a consumer is generally
  • 0.95 lagging
  • Unity
  • 0.6 lagging
  • 0.4 lagging
Answer: A
3.The length of a short transmission line is upto about
  • 50km
  • 120km
  • 200km
  • 240km
Answer: A
4.When the regulation is positive then receiving and voltage (Vr) is __ then sending and voltage (Vs).
  • More
  • Less
  • Equal
  • None
Answer: B
5.30<100×60<20° =
  • 2<2°
  • 1800<30°
  • 1800<2°
  • 2<30°
Answer: B
6. ______ fault gives rise to asymmetrical fault currents.
  • Single phase to ground
  • phase to phase
  • 3- phase short circuit
  • None
Answer: C
7.If the %age reactance of the system upto the fault point is 20% & the above KVA is 10,000 ,then short circuit KVA is -----------
  • 50000
  • 10000
  • 2000
  • 20000
Answer: A
8.At full load, the current induced in the rotor conductor of a 3-¢ squirrel cage induction motor is
  • More than rated current
  • more than no. of stator poles
  • Less than rated current
  • None of the above
Answer: C
9.Speed of one squirrel cage induction motor can be controlled by
  • Changing supply frequency
  • Changing number of poles
  • Reducing supply voltage
  • All of the above
Answer: A
10.The speed of the slip ring induction motor can be controlled by
  • Changing supply frequency
  • Changing number of poles
  • Changing the resistance of the rotor winding
  • All the above
Answer: C
11.The power factor of an A.C circuit is given by ____________ power divided by ______ power.
Answer: Active, Apparent
12.The major reason for low lagging power factor of supply system is due to the use of _________ motors.
Answer: Induction
13._______ Of transmission lines, is the most important cause of power loss in the lines.
Answer: Resistance
14.In any transmission line, AD - BC = ________.
Answer: 1
15.If the pf of load decreases, the line losses ________.
Answer: Increases
16.The most common type of fault in overhead lines is _____________.
Answer: phase – to – ground fault
17.Short circuit kVA is obtained by multiplying the base kVA by __________.
Answer: 5
18.Reactors are used at various points in the power system to _______________l.
Answer: Limit short-circuit current
19.When all the three phases are short circuited, it gives rise to ____________ currents.
Answer: Symmetrical fault.
20.An over- excited synchronous motor on no load is known as ______________.
Answer: Synchronous condenser.