Deck 3: Electrical Measurement and Testing

Question 1

Generally grounding is provided for:

A)only for the safety of the equipment
B)only for the safety of the operating personnel
C)both (a) and (b)
D)none of the above

Answer 1

both (a) and (b)

Question 2

Ground resistance should be designed such that:

A)grounding resistance should be as low as possible
B)grounding resistance should be as high as possible
C)grounding resistance should be always zero
D)none of the above

Answer 2

grounding resistance should be as low as possible

Question 3

The objective of earthing or grounding is:

A)to provide as low resistance possible to the ground
B)to provide as high resistance possible to the ground
C)to provide flow of positive, negative and zero sequence currents
D)none of the above

Answer 3

to provide as low resistance possible to the ground

Question 4

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.

Question 5

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.

Question 6

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.

Question 7

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.

Question 8

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.

Question 9

A potentiometer may be used for

A)measurement of resistance
B)measurement of current
C)calibration of voltmeter
D)all of the above

Question 10

--------- 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

Question 11

For measuring a very high resistance we should use

A)kelvin\s double bridge
B)wheat stone bridge
C)meggar
D)none of the above

Question 12

The electrical power to a meggar is provided by

A)battery
B)permanent magnet d.c. generator
C)ac. generator
D)any of the above

Question 13

In a meggar controlling torque is provided by

A)spring
B)gravity
C)coil
D)eddy current

Question 14

The operating voltage of a meggar is about

A)6 v
B)12 v
C)40 v
D)100 v

Question 15

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

Question 16

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

Question 17

In an Anderson bridge, the unknown inductance is measured in terms of

A)known inductance and resistance
B)known capacitance and resistance
C)known resistance
D)known inductance

Question 18

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°

Question 19

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

A)magnetic screening
B)wagner earthing device
C)wave filters
D)any of the above

Question 20

Standard resistor is made from

A)platinum
B)maganin
C)silver
D)nichrome

Question 21

Commonly used standard capacitor is

A)spherical type
B)concentric cylindrical type
C)electrostatic type
D)multilayer parallel plate type

Question 22

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

Question 23

Loss of charge method is used to measure:

A)low r
B)high r
C)low l
D)high l

Question 24

Megger is an instrument used for the measurement of:

A)high resistance and insulation resistance
B)medium resistance
C)low resistance
D)leakage current

Question 25

Anderson bridge is used to measure of:

A)inductance
B)capacitance
C)time period
D)resistance and capacitance