Deck 2: Instrumentation and Electrical Engineering

Question 1

Which of the following properties a damping oil must possess ?

A)must be a good insulator
B)should not have corrosive action upon the metal of the vane
C)the viscosity of the oil should not change with the temperature
D)all of the above

Answer 1

all of the above

Question 2

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 2

all of the above

Question 3

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 3

current transformers

Question 4

The pointer of an indicating instrument should be

A)very light
B)very heavy
C)either (a) or (b)
D)neither (a) nor (b)

Question 5

In majority of instruments damping is provided by

A)fluid friction
B)spring
C)eddy currents
D)all of the above

Question 6

An ammeter is a

A)secondary instrument
B)absolute instrument
C)recording instrument
D)integrating instrument

Question 7

In a portable instrument, the controlling torque is provided by

A)spring
B)gravity
C)eddy currents
D)all of the above

Question 8

The desirable static characteristics of a measuring system are

A)accuracy and reproducibility
B)accuracy, sensitivity and reproducibility
C)drift and dead zone
D)static error

Question 9

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

Question 10

Systematic errors are

A)instrumental errors
B)environmental errors
C)observational errors
D)all of the above

Question 11

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

Question 12

Instrument transformers are

A)potential transformers
B)current transformers
C)both (a) and (b)
D)power transformers

Question 13

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

Question 14

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

Question 15

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

Question 16

The turns ratio for C.T. is defined as

A)n2/n1
B)n1/n2
C)(n1+n2)/n1
D)(n1+n2)/n2

Question 17

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

Question 18

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

Question 19

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)

Question 20

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

Question 21

Potentiometer is an __ instrument:

A)indicating
B)comparison
C)calibrating
D)recording

Question 22

Which of the following bridge is frequency sensitive:

A)wheatstone bridge
B)maxwell bridge
C)anderson bridge
D)wien bridge

Question 23

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)

Question 24

Earth wire or ground wire is made of:

A)copper
B)aluminium
C)iron
D)galvanized steel

Question 25

Average resistance of human body is:

A)500 ohms
B)1000 ohms
C)1500 ohms
D)2000 ohms