ELECTRICAL ENGINEERING BITS-8

1.

In submerged arc furnace the power is controlled by ______?

 Either Varying the spacing between the electrodes or Varying the voltage applied to the electrodes.

2.

The minority carrier concentration is largely a function of

 temperature

3.

The insulating material should have
 all of these 

4.

In illumination technology total lumens emitted by source / total lumens available after waste of light is equal to _______?

 waste light factor.

5.

A control system in which the control action is somehow dependent on the output is known as
 Closed loop system 

6.

Overload capacity of diesel engines is usually restricted to

 2 percent

7.

Constantan contains
 copper and nickel 

8.

The current carrying capacity of cables in D.C. is more than that in A.C. mainly due to
 smaller dielectric loss 

9.

According to application, instruments are classified as
 Both switch board and portable 

10.

A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is

 high starting torque

11.

Specified quantities of load bus are ______?
 P and Q 

12.

The design of mechanical parts is particularly important in case of _____ speed machines.

 high

13.

Automatic signalling is used for which of the following trains ?

 Superfast trains

14.

Operating torques in analogue instruments are
 deflecting, control and damping 

15.

Zero initial condition for a system means

 system is at rest and no energy is stored in any of its components

16.

Murray loop test can be used for location of

 both the ground fault and the short-circuit fault

17.

In a stepper motor the detente torque means ???

 minimum of the static torque with the phase winding unexcited.

18.

The principle on which vector voltmeter is based is
 that it measures the amplitude of a single at two points and at the same time measures their phase difference 

19.

To reduce the radio interference which line is/are transposed?

 Both of these

20.

In which of the following applications the load on motor changes in cyclic order ?
 All of these 

21.

In transmission lines distribution constants are ??
 resistance, inductance and capacitance 

22.

Heat is transferred simultaneously by condition, convection and radiation

 inside boiler furnaces

23.

Which of the following is/are the methods to reduce the armature reaction and its effects?
 All of these 

24.

The thermal conductivity of hydrogen is ______ times that of air.

 7

25.

Helical windings are used in
 power transformers 

26.

The function(s) of an heating chamber is/are to ________
 All of these 

27.

Non-linear resistors

 produce harmonic distortion

28.

Capacitor start capacitor run provides ________
 high staring torque and high power factor. 

29.

The braking retardation is usually in the range

 3 to 5 km phps

30.

Proximity effect depends on _______?
 All of these 

31.

The supply frequency usually employed for high frequency eddy current heating is ________
 10 KHz to 400 KHz. 

32.

The material for armouring on cable is usually

 any of these

33.

Induction type single phase energy meters measure electric energy in
 kWh 

34.

Demagnetization effects which of the following?

 reduction in main field flux and reduces the terminal voltage

35.

Which of the following motors is usually preferred for kiln drives ?

 Any one of these

36.

_______ is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another,
 Meggar 

37.

Overhead telephone wires are made of

 steel

38.

Which of the following insulation is used in cables ?
 all of these 

39.

Which of the following methods is used to control speed of 25 kV, 50 Hz single phase traction ?

 Tap changing control of transformer

40.

A closed loop system is distinguished from open loop system by which of the following ?
 Feedback 

41.

The coasting retardation is around
 0.16 km phps 

42.

If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be
 15 cm 

43.

Surface resistance of an insulating material is reduced due to the
 both smoky and dirty atmosphere and humidity in the atmosphere 

44.

Which of the following is an open loop control system ?

 Field controlled D.C. motor

45.

A control system with excessive noise, is likely to suffer from

 saturation in amplifying stages

46.

The conduction of electricity, in semiconductors, takes place due to movement of
 electrons and holes 

47.

Commercial available medium size machines have a speed range of ______ .

 2000 to 2500 r.p.m.

48.

Circuit breakers are essentially
 current carrying contacts called electrodes 

49.

The process of heat transfer during the reentry of satellites and missiles, at very high speeds, into earth's atmosphere is known as
 ablation 

50.

Energy consumption in propelling the train is required for which of the following?
 All of these 

51.

Maximum power developed is depends on ______?
 Both of these 

52.

The overall efficiency of steam locomo¬tive is around

 5 to 10 percent

53.

Battery operated trucks are used in
 factories for material transportation 

54.

In an energymeter braking torque is produced to

 maintain steady speed and equal to driving torque

55.

The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a

 two-phase winding

56.

In a system zero initial condition means that
 The system is at rest and no energy is stored in any of its components 

57.

If sparsity of a 5 bus transmission line is 0.4. Find the number of transmission lines?

 5

58.

_____ is the main constituent of glass
 Si02 

59.

Advantages of shunt compensation is/are _______

 It requires less maintanance

60.

Range of accelerating factor is
 1.6 to 1.8 

61.

The horsepower of steam locomotives is
 upto 1500 

62.

In most condition which frame of motor will be preferred?
 Totally enclosed fan coiled. 

63.

The ratio of maximum displacement deviation to full scale deviation of the instrument is called

 linearity

64.

Insulating materials have the function of
 preventing a short circuit between conducting wires 

65.

High tension cables are generally used upto

 11kV

66.

Low resistivity materials are used in
 all of these 

67.

To avoid the effect of stray magnetic field in A.C. bridges we can use

 magnetic screening

68.

Aluminium is now most commonly employed conductor material in transmission lines than copper because _____
 it is cheaper and lighter 

69.

Wagner earthing device is used to eliminate errors due to

 electrostatic coupling

70.

In synchronous motor, the damper winding is generally used to ____?
 prevent hunting and provide the starting torque. 

71.

The number of atoms per unit cell in B.C.C. structure is

 2

72.

Mercury as an electric contact material is
 a metal liquid 

73.

The adjustment of position of shading bands, in an energy meter is done to provide

 friction compensation

74.

Transmission lines are transposed to reduce __________?
 interference with neighbouring communication lines 

75.

The density of hydrogen is _____ times the density of air.

 0.07

76.

The rate of acceleration on suburban or urban services is restricted by the consideration of
 Passenger Discomfort 

77.

Which of the following are non-conductors of electricity?
 all of these 

78.

Number of slip rings in 3-phase synchronous motor will be _______?

 2 or 3

79.

In salient pole synchronous machine, maximum power occurs at a load angle of ??

 less than 90°

80.

Maximum power transfer in a transmission line can be obtained by _____?
 Both of these 

81.

In case of a steam engine an average coal consumption per km is nearly

 28 to 30 kg

82.

Which of the following motors are suitable for computer printer drive ?
 Stepper motor. 

83.

For dielectric heating the range of frequency normally employed is ________. 
 10 MHz to 40 MHz.

84.

With conventional hydrogen cooling it is possible to increase the rating of a single unit to
 200 MW 

85.

When a bogie negotiates a curve, reduction in adhesion occurs resulting in sliding. Thus sliding is acute when
 Both wheel base of axles is more and degree of curvature is more 

86.

For a hole which of the following statements is incorrect ?

 Holes can exist in any material including conductors

87.

The slot leakage can be calculated by making which of the following assumptions ?
 All of these 

88.

The efficiency of diesel locomotives is nearly

 20 to 25 percent

89.

The statement which is not correct from the following:
 For a uniform long charged line with l1 c/m the electric field intensity E is given as E = ?L/(p e0.r). 

90.

The frequency and time domain are related through which of the following?
 Laplace Transform and Fourier Integral 

91.

The voltage control in electric supply networks in required on account of which of the following reasons ?
 All of these 

92.

In a meggar controlling torque is provided by

 coil

93.

In a cable the voltage stress is maximum at
 core of the conductor 

94.

Advantages of gauss siedel method is/are _______?
 calculation time for each iteration is less 

95.

A phase shifting transformer is used in conjunction with
 Drysdale potentiometer 

96.

For germanium the forbidden energy gap is
 0.7eV 

97.

Which of the following methods is most accurate ?

 Equivalent current method

98.

Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ?
 The system is highly oscillatory 

99.

Which part of a motor needs maximum attention for maintenance ?
 Rearing