In an electro dynamometer type of wattmeter , the inductance of the pressure coil circuit produces error :

which is lower at low power factors

which is constant irrespective of the power factor of the load

which is higher at low power factors

which is lower at low power factors

In electro dynamometer type of wattmeter current coils designed for carrying heavy currents use stranded wires or laminated conductors :

to reduce eddy current losses in the conductors

The power factor of a single phase load can be calculated if the instruments available are

one voltmeter, one ammeter and one energy meter

one voltmeter, one ammetqr and one wattmeter

one voltmeter, one ammeter and one energy meter

The braking torque provided by a permanent magnet in a single phase energy meter is proportional to the

square of the flux of the permanent magnet

distance of the permanent magnet from the centre of the revolving disc

Hole s are drilled on the opposite sides of the spindle of an energy meter to avoid

dissipate heat generated due to eddy currents

A bridge circuit works at a frequency of 2KHz, the following can be used as detectors for detection of null conditions in the bridge:

vibration galvanometers and tunable amplifiers.

vibration galvanometers and headphones

headphones and tunable amplifiers.

vibration galvanometers and tunable amplifiers.

vibration galvanometers, headphones and tunable amplifiers.

High resistances are provided with a guard terminal. This guard terminal is used to :

guard the resistance against stray electrostatic fields

guard the resistance against over loads.

Which of the following devices should be used for accurate measurement of low D.C. voltage ?

small range thermocouple voltmeter

small range moving coil voltmeter

small range thermocouple voltmeter

A moving iron ammeter coil has few turns of thick wire in order to have:

low resistance and large current carrying capacity

A megger indicates infinity when test terminals are open-circuited. This is because:

no current flows through the pressure coil

no current flows through the current coil

no current flows through the pressure coil

no current flows through the compensating winding

current does not flow through current coil and pressure coil

While testing cables the galvanometer used should be initially short-circuited in order to protect it from sudden initial inrush currents as the cable have:

a low value of initial resistance

a low value of initial capacitance

a high value of initial capacitance

The size of the earth or ground wire is based on the:

maximum fault current carrying through the ground wire

rated current carrying capacity of the service line

The spring material used in a spring control device should have thefollowing property.

most be of low temperature co-efficient

should have low specific resistance

Hole s are drilled on the opposite sides of the spindle of an energy meter toavoid

dissipate heat generated due to eddy currents

The vale of resistance of an earthing electrode depends upon

shape and material of the electrode

depth to which electrode is driven into earth

The major advantage of electromagnet type meter over a permanent magnetmeter is

. the electromagnet meter costs much less

the permanent magnet meter has a more sluggish coil

. the electromagnet meter need not be aligned with the earth’s magnetic field

. the electromagnet meter is more rugged

A galvanometer can be used for measuring current and voltage of a circuitby:

without shunt and series resistance

connecting high value of resistance in series only

shunt for measuring current and high resistance in series for voltage

without shunt and series resistance

In an electro dynamometer type of wattmeter

any of the two coils current coil or pressure coil can be made fixed.

both the coils should be movable.

134 + Mcqs in Electromagnetic Interference in Electrical Engineering Page 1 McqOptions

1.	The adjustment of position of shading bands, in an energy meter is done to provide
A.	friction compensation
B.	creep compensation
C.	braking torque
D.	none of the above
Answer» B. creep compensation

Discussion

2.	In an electro dynamometer type of wattmeter , the inductance of the pressure coil circuit produces error :
A.	which is constant irrespective of the power factor of the load
B.	which is higher at low power factors
C.	which is lower at low power factors
D.	none of the above.
Answer» C. which is lower at low power factors

Discussion

3.	In electro dynamometer type of wattmeter current coils designed for carrying heavy currents use stranded wires or laminated conductors :
A.	to reduce iron losses
B.	to reduce hysteresis losses
C.	to reduce eddy current losses in the conductors
D.	all of the above.
Answer» D. all of the above.

Discussion

4.	The resistance in the circuit of the moving coil of a dynamometer wattmeter should be
A.	almost zero
B.	low
C.	high
D.	none of the above
Answer» D. none of the above

Discussion

5.	The pressure coil of a wattmeter should be connected on the supply side of the current coil when
A.	load impedance is high
B.	load impedance is low
C.	supply voltage is low
D.	none of the above
Answer» B. load impedance is low

Discussion

6.	In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at
A.	0
B.	60
C.	90
D.	120
Answer» E.

Discussion

7.	The power factor of a single phase load can be calculated if the instruments available are
A.	one voltmeter and one ammeter
B.	one voltmeter, one ammetqr and one wattmeter
C.	one voltmeter, one ammeter and one energy meter
D.	any of the above
Answer» C. one voltmeter, one ammeter and one energy meter

Discussion

8.	The braking torque provided by a permanent magnet in a single phase energy meter is proportional to the
A.	square of the flux of the permanent magnet
B.	speed of the meter
C.	distance of the permanent magnet from the centre of the revolving disc
D.	all of the above.
Answer» E.

Discussion

9.	Hole s are drilled on the opposite sides of the spindle of an energy meter to avoid
A.	balance of the disc
B.	dissipate heat generated due to eddy currents
C.	avoid creep on load
D.	increase the deflection torque
Answer» D. increase the deflection torque

Discussion

10.	Swamping of resistance is used to compensate error due to:
A.	stray magnetic field
B.	temperature variations
C.	large supply variations
D.	none of the above
Answer» C. large supply variations

Discussion

11.	In an Induction type energy meter, maximum torque is obtained when the parameter of the rotating disc are
A.	r=0
B.	x=0
C.	r=x
D.	none of the above
Answer» C. r=x

Discussion

12.	In an induction type energy meter, compensation for static friction is provided by
A.	drilling holes in the disc
B.	lag circuits
C.	shading bands
D.	none of the above
Answer» D. none of the above

Discussion

13.	A bridge circuit works at a frequency of 2KHz, the following can be used as detectors for detection of null conditions in the bridge:
A.	vibration galvanometers and headphones
B.	headphones and tunable amplifiers.
C.	vibration galvanometers and tunable amplifiers.
D.	vibration galvanometers, headphones and tunable amplifiers.
Answer» C. vibration galvanometers and tunable amplifiers.

Discussion

14.	Maxwell s inductance capacitance bridge is used for measurement of inductance of:
A.	low q coils
B.	medium q coils
C.	low and medium q coils
D.	none of the above.
Answer» C. low and medium q coils

Discussion

15.	High resistances are provided with a guard terminal. This guard terminal is used to :
A.	bypass leakage current
B.	guard the resistance against stray electrostatic fields
C.	guard the resistance against over loads.
D.	none of the above.
Answer» B. guard the resistance against stray electrostatic fields

Discussion

16.	The wheatstone bridge cant be used for precision measurements because errors are introduce into on account of :
A.	resistance of connecting leads
B.	thermo electric emf
C.	contact resistances
D.	all of the above.
Answer» E.

Discussion

17.	--------- is an instrument which measures the insulation resistance of an electric circuit relative to earth and one another,
A.	tangent galvanometer
B.	meggar
C.	current transformer
D.	none of the above
Answer» C. current transformer

Discussion

18.	Which of the following devices should be used for accurate measurement of low D.C. voltage ?
A.	small range moving coil voltmeter
B.	d.c. potentiometer
C.	small range thermocouple voltmeter
D.	none of the above
Answer» C. small range thermocouple voltmeter

Discussion

19.	For handling greater currents induction wattmeters are used in conjunction with
A.	potential transformers
B.	current transformers
C.	power transformers
D.	either of the above
Answer» C. power transformers

Discussion

20.	If the current in a capacitor leads the voltage by 80 , the loss angle of the capacitor is
A.	10
B.	80
C.	120
D.	170
Answer» B. 80

Discussion

21.	It is required to measure the true open circuit e.m.f. of a battery. The best device is
A.	d.c. voltmeter
B.	ammeter and a known resistance
C.	d.c. potentiometer
D.	none of the above
Answer» D. none of the above

Discussion

22.	Which of the following devices may be used for extending the range of instruments ?
A.	shunts
B.	multipliers
C.	current transformers
D.	all of the above
Answer» E.

Discussion

23.	The damping force acts on the moving system of an indicating instruments only when it is
A.	moving
B.	stationary
C.	near its full scale deflection
D.	just staring to move
Answer» B. stationary

Discussion

24.	The most commonly used null deflector in a power frequency ac bridge is a
A.	vibration galvanometer
B.	d arsanval galvanometer
C.	ballistic galvanometer
D.	tachometer
Answer» B. d arsanval galvanometer

Discussion

25.	A moving iron ammeter coil has few turns of thick wire in order to have:
A.	high sensitivity
B.	effective damping
C.	low resistance and large current carrying capacity
D.	large scale
Answer» D. large scale

Discussion

26.	A megger indicates infinity when test terminals are open-circuited. This is because:
A.	no current flows through the current coil
B.	no current flows through the pressure coil
C.	no current flows through the compensating winding
D.	current does not flow through current coil and pressure coil
Answer» B. no current flows through the pressure coil

Discussion

27.	A 3810/63 P.T. is used with a voltmeter gives reading of 28.11 V , then the actual line voltage is ------ V
A.	0.4648
B.	975
C.	1700
D.	1100
Answer» D. 1100

Discussion

28.	A 1000:5 C.T. is used with an ammeter. If ammeter reading is 1.8 A then the actual line current is --------------A
A.	160
B.	400
C.	0.09
D.	360
Answer» E.

Discussion

29.	While testing cables the galvanometer used should be initially short-circuited in order to protect it from sudden initial inrush currents as the cable have:
A.	a low value of initial resistance
B.	a low value of initial capacitance
C.	a high value of initial capacitance
D.	both (a) and (b)
Answer» D. both (a) and (b)

Discussion

30.	The ratio of maximum displacement deviation to full scale deviation of the instrument is called
A.	static sensitivity
B.	dynamic deviation
C.	linearity
D.	precision or accuracy
Answer» D. precision or accuracy

Discussion

31.	The gravity controlled instrument has crowded scale because current is proportional to
A.	balancing weight
B.	deflection angle
C.	sine of deflection angle
D.	none of the above
Answer» D. none of the above

Discussion

32.	Which type of damping is used in Induction type energy meter?
A.	air friction
B.	fluid friction
C.	gravity
D.	eddycurrent
Answer» E.

Discussion

33.	C.R.O gives
A.	actual representation
B.	visual representation
C.	approximate representation
D.	incorrect representation
Answer» C. approximate representation

Discussion

34.	The size of the earth or ground wire is based on the:
A.	maximum fault current carrying through the ground wire
B.	rated current carrying capacity of the service line
C.	depends on the soil resistance
D.	both (a) and (c)
Answer» E.

Discussion

35.	The adjustment of position of shading bands, in an energy meter is done toprovide
A.	friction compensation
B.	creep compensation
C.	braking torque
D.	none of the above
Answer» B. creep compensation

Discussion

36.	The spring material used in a spring control device should have thefollowing property.
A.	should be non-magnetic
B.	most be of low temperature co-efficient
C.	should have low specific resistance
D.	all of the above
Answer» E.

Discussion

37.	Deflection system of a CRT consists of
A.	4 plates
B.	6 plates
C.	2 plates
D.	8 plates
Answer» D. 8 plates

Discussion

38.	Commonly used elements for wire strain gauges are
A.	nickel and copper
B.	nickel and gold
C.	gold and brass
D.	silver and aluminium
Answer» B. nickel and gold

Discussion

39.	Hole s are drilled on the opposite sides of the spindle of an energy meter toavoid
A.	balance of the disc
B.	dissipate heat generated due to eddy currents
C.	avoid creep on load
D.	increase the deflection torque
Answer» D. increase the deflection torque

Discussion

40.	CRO is a
A.	fast x-y plotter
B.	slow x-y plotter
C.	medium x-y plotter
D.	not a plotter
Answer» B. slow x-y plotter

Discussion

41.	A _____ device prevents the oscillation of the moving system andenables the latter to reach its final position quickly
A.	deflecting
B.	controlling
C.	damping
D.	any of the above
Answer» D. any of the above

Discussion

42.	_____ instruments are those which measure the total quantity of electricitydelivered in a particular time.
A.	absolute
B.	indicating
C.	recording
D.	integrating
Answer» E.

Discussion

43.	McLeod gauge used for measurement of
A.	high pressure
B.	low pressure
C.	very high pressure
D.	pressure
Answer» C. very high pressure

Discussion

44.	In an induction type energy meter, compensation for static friction isprovided by
A.	drilling holes in the disc
B.	lag circuits
C.	shading bands
D.	none of the above
Answer» D. none of the above

Discussion

45.	The damping force acts on the moving system of an indicating instrumentsonly when it is
A.	moving
B.	stationary
C.	near its full scale deflection
D.	just staring to move
Answer» B. stationary

Discussion

46.	The vale of resistance of an earthing electrode depends upon
A.	shape and material of the electrode
B.	depth to which electrode is driven into earth
C.	specific resistance of soil
D.	all of the above.
Answer» E.

Discussion

47.	The major advantage of electromagnet type meter over a permanent magnetmeter is
A.	. the electromagnet meter costs much less
B.	the permanent magnet meter has a more sluggish coil
C.	. the electromagnet meter need not be aligned with the earth’s magnetic field
D.	. the electromagnet meter is more rugged
Answer» E.

Discussion

48.	Which of the following instruments indicate the instantaneous value of theelectrical quantity being measured at the time at which it is being measured ?
A.	absolute instruments
B.	indicating instruments
C.	recording instruments
D.	integrating instruments
Answer» C. recording instruments

Discussion

49.	A galvanometer can be used for measuring current and voltage of a circuitby:
A.	shunt only
B.	connecting high value of resistance in series only
C.	shunt for measuring current and high resistance in series for voltage
D.	without shunt and series resistance
Answer» D. without shunt and series resistance

Discussion

50.	In an electro dynamometer type of wattmeter
A.	the current coil is made fixed
B.	the pressure coil is fixed
C.	any of the two coils current coil or pressure coil can be made fixed.
D.	both the coils should be movable.
Answer» B. the pressure coil is fixed

Discussion

Explore topic-wise MCQs in Electrical Engineering.

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

In an electro dynamometer type of wattmeter , the inductance of the pressure coil circuit produces error :

In electro dynamometer type of wattmeter current coils designed for carrying heavy currents use stranded wires or laminated conductors :

The resistance in the circuit of the moving coil of a dynamometer wattmeter should be

The pressure coil of a wattmeter should be connected on the supply side of the current coil when

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

The power factor of a single phase load can be calculated if the instruments available are

The braking torque provided by a permanent magnet in a single phase energy meter is proportional to the

Hole s are drilled on the opposite sides of the spindle of an energy meter to avoid

Swamping of resistance is used to compensate error due to:

In an Induction type energy meter, maximum torque is obtained when the parameter of the rotating disc are

In an induction type energy meter, compensation for static friction is provided by

A bridge circuit works at a frequency of 2KHz, the following can be used as detectors for detection of null conditions in the bridge:

Maxwell s inductance capacitance bridge is used for measurement of inductance of:

High resistances are provided with a guard terminal. This guard terminal is used to :

The wheatstone bridge cant be used for precision measurements because errors are introduce into on account of :

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

Which of the following devices should be used for accurate measurement of low D.C. voltage ?

For handling greater currents induction wattmeters are used in conjunction with

If the current in a capacitor leads the voltage by 80 , the loss angle of the capacitor is

It is required to measure the true open circuit e.m.f. of a battery. The best device is

Which of the following devices may be used for extending the range of instruments ?

The damping force acts on the moving system of an indicating instruments only when it is

The most commonly used null deflector in a power frequency ac bridge is a

A moving iron ammeter coil has few turns of thick wire in order to have:

A megger indicates infinity when test terminals are open-circuited. This is because:

A 3810/63 P.T. is used with a voltmeter gives reading of 28.11 V , then the actual line voltage is ------ V

A 1000:5 C.T. is used with an ammeter. If ammeter reading is 1.8 A then the actual line current is --------------A

While testing cables the galvanometer used should be initially short-circuited in order to protect it from sudden initial inrush currents as the cable have:

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

The gravity controlled instrument has crowded scale because current is proportional to

Which type of damping is used in Induction type energy meter?

C.R.O gives

The size of the earth or ground wire is based on the:

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

The spring material used in a spring control device should have thefollowing property.

Deflection system of a CRT consists of

Commonly used elements for wire strain gauges are

Hole s are drilled on the opposite sides of the spindle of an energy meter toavoid

CRO is a

A _____ device prevents the oscillation of the moving system andenables the latter to reach its final position quickly

_____ instruments are those which measure the total quantity of electricitydelivered in a particular time.

McLeod gauge used for measurement of

In an induction type energy meter, compensation for static friction isprovided by

The damping force acts on the moving system of an indicating instrumentsonly when it is

The vale of resistance of an earthing electrode depends upon

The major advantage of electromagnet type meter over a permanent magnetmeter is

Which of the following instruments indicate the instantaneous value of theelectrical quantity being measured at the time at which it is being measured ?

A galvanometer can be used for measuring current and voltage of a circuitby:

In an electro dynamometer type of wattmeter