ELECTRICAL ENGINEERING BITS-1

1.

Breadth factor is defined as the ratio of ??
 emf with distributed winding to emf with concentrated winding 

2.

An elevator drive is required to operate in

 four quadrants.

3.

The total number of strands in a ACSR conductor are 7, then find the layer number?

 2

4.

The internal flux linkage due to internal flux of a conductor is __________?
 I/2*10-7 wb-T/m 

5.

Belted slip ring induction motor is almost invariably used for
 jaw crushers 

6.

Long distance railways use which of the following ?
 25 kV single phase A.C. 

7.

Steel wire is used as

 all of these

8.

If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be

 10 kV/mm

9.

An ohmmeter is a

 moving coil instrument

10.

Cables for 220 kV lines are invariably
 compressed oil or compressed gas insulated 

11.

The charging reactance of 50 km transmission line is 1500 Ω. What is the charging reactance for 100 km length of line?

 750 O

12.

Specified quantities of slack bus are _______
 V and d 

13.

Universal motor have which of the following application?
 Food mixer. 

14.

As a result of introduction of negative feedback which of the following will not decrease ?
 Band width 

15.

Specific energy consumption is least in _______ service.
 main line 

16.

Capacitor in split phase induction motor is used for __________?

 starting the motor

17.

The flash point of transformer oil should be higher than
 104°C 

18.

Ferranti effect can be compensated by which of the following ?
 shunt reactor 

19.

Flux density under leading pole tips in case of generator will _____?

 decrease

20.

Synchronous capacitor is _______ ??
 an over excited synchronous motor without mechanical load 

21.

The minimum charge on an ion is
 equal to the charge of an electron

22.

In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of

 0.5 Hz

23.

__________method has leading power factor
 Dielectric heating 

24.

Induction furnaces are employed for which of the following ?

 Heat treatment of castings

25.

Any externally introduced signal affecting the controlled output is called a

 stimulus

26.

Polarity of supply voltage is reversed in which type of braking?
 Plugging. 

27.

The surge resistance of cable is

 50 ohms

28.

Which of the following motor used in hair dryers?
 Shaded pole IM. 

29.

Two resistors are said to be connected in series when

 same current passes in turn through both

30.

The initial response when tne output is not equal to input is called
 Transient response 

31.

Under excited Synchronous phase modifier works as ______?
 shunt reactor 

32.

A 1000 W bulb fitted with a reflector illuminates an area of 3 m × 3 m with an average illumination of 450 lux. If the bulb has and efficiency of 9 lumens / watt the efficiency of the reflector is ______?

 45 %.

33.

In synchronous motor the torque is proportional to _______?
 Power P 

34.

Heat control switches are used in

 cooling ranges

35.

An induction meter can handle current upto

 100 A

36.

In ________ the speed can be varied by changing the position of brushes.

 schrage motor

37.

For which of the following applications motor has to start with high acceleration?
 Lifts and hoists 

38.

In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be

 0.5

39.

Battery operated scooter for braking uses

 mechanical braking

40.

Which of the following will happen if the thickness of refractory wall of furnace is increased ?

 Temperature on the outer surface of furnace walls will drop

41.

If an AC servomotor has one of its winding excited by AC, then voltage measured at the other winding with rotor running will be

 proportional to rotor speed.

42.

The superconductivity is due to

 the crystal structure having no atomic vibration at 0°K

43.

The effect of ------------------ on main field flux is armature reaction?
 armature flux 

44.

An inverted V-curve of synchronous motor shows the variation of _____?
 power factor and dc excitation at constant load 

45.

An electric dipole of moment P is placed in front of a ground sphere. The change induced on the surface of the sphere is (Assume radius of sphere = R and distance from dipole to centre of sphere = d)

 PR/d2.

46.

Thermal overload relays are used to protect the motor against over current due to
 heavy loads 

47.

cables are used for 132 kV lines.
 Extra super voltage 

48.

________are used for construction of core of electromagnets.
 Soft magnetic materials 

49.

The second derivative input signals modify which of the following ?
 The time constant and suppress the oscillations 

50.

In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at

 120°

51.

The torque speed characteristics of a AC servomotor is approximately?

 linearised

52.

Pressure cables are generally not used beyond
 66 kV 

53.

The term self GMD is used to calculate ______
 inductance 

54.

The value of co-efficient of adhesion will be high when rails are
 cleaned with sand 

55.

When a capacitor was connected to the terminal of ohmmeter, the pointer indicated a low resistance initially and then slowly came to infinity position. This shows that capacitor is
 all right 

56.

Shunt field of DC generators consists of--------number of turns and ---------- conductors respectively
 large and thin 

57.

Which of the following braking systems is used on steam locomotives ?

 Vacuum system

58.

If the diameter of the conductor is increased ______
 the inductance is decreased 

59.

Hunting in a synchronous cannot be due to _______?
 windage friction. 

60.

Main traction systems used in India are, those using
 all of these 

61.

________are always double layer type.
 Closed windings 

62.

For n bus power system size of Y bus matrix is ___________?
 n×n 

63.

A 8 pole, 50 Hz single phase induction motor is running at 690 rpm. Its slip with respect to forward field is

 0.08

64.

With feedback _____ increases.

 system stability

65.

For flat voltage profile system, voltage regulation is ____

 0%

66.

Overhead lines for power supply to tramcars are at a minimum height of

 10 m

67.

The winding where dummy coils are used is sometimes called
 forced winding 

68.

Mass, in force-voltage analogy, is analogous to

 inductance

69.

The heat dissipated by _____radiation from a surface depends upon its temperature and its characteristics like colour, roughness etc.
 radiation 

70.

A signal other than the reference input that tends to affect the value of controlled variable is known as

 disturbance

71.

A 4 pole lap wound dc generator has 4 brushes, if one of the brush is damaged, what will be the change in V, I and P ratings ______?
 V, I/2 and P/2 

72.

Which of the following materials is used for making coils of standard resistances ?
 Manganin 

73.

The skin effect shows that __________?
 current density is more at the surface of the condutor 

74.

D.C. shunt relays are made of

 many turns of thin wire

75.

The conductivity of a conductor can be increased by

 increasing its temperature

76.

Which of the following variety of copper has the best conductivity ?

 Pure annealed copper

77.

In a 1-phase induction motor, if the forward torque slip is S, what is the backward torque slip?
 2-S 

78.

Co-efficient of adhesion is

 low in case of D.C. traction than in the case of AC. traction

79.

Which is the best conductor of electricity ?
 Silver 

80.

The electrical power to a meggar is provided by
 permanent magnet D.C. generator 

81.

The electrode of a direct arc furnace is made of

 graphite

82.

Ward-Leonard controlled D.C. drives are generally used for ______ excavators.

 Heavy duty

83.

________ has the highest value of thermal conductivity.

 Copper

84.

Yokes with rectangular cross-section are used for
 small capacity transformers 

85.

The transient response of a system is mainly due to
 stored energy 

86.

In salient pole synchronous machine, the reluctance power varies as _______?
 sin2d 

87.

Which of the following is the output of a thermocouple ?

 D.C. voltage

88.

A.C. servomotor is basically a
 two phase induction motor 

89.

High braking torque produced in __________

 plugging.

90.

All of the following are equivalent to watt except
 amperes/volt 

91.

With direct water cooling it is possible to have ratings of about

 600 MW

92.

The kinetic energy of a bounded electron is
 less than that of unbounded electron 

93.

In case of _______ speed control by injecting e.m.f. in the rotor circuit is possible.
 slip ring induction motor 

94.

_____ instruments are those which measure the total quantity of electricity delivered in a particular time.
 Integrating 

95.

Dielectric strength of rubber is around

 30 kV/mm

96.

Which of the following machines has heavy fluctuation of load ?
 Punching machine 

97.

E.m.f. of a Weston cell is accurately measured by

 electrostatic voltmeter

98.

For open control system which of the following statements is incorrect ?
 Recalibration is not required for maintaining the required quality of the output 

99.

Surge impedance loading of a 3-phase, 400 kV transmission line is 400 Ω. The surge impedance loading is ________

 400 MW

100.

For a motor-generator set which of the following motors will be preferred ?

 Synchronous motor