Question 1

Which of the following properties a damping oil must possess ?

Accepted Answer

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 D

Question 2

The desirable static characteristics of a measuring system are

Accepted Answer

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

Question 3

The turns ratio for C.T. is defined as

Accepted Answer

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

Question 4

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

Accepted Answer

A)  static sensitivity
B)  dynamic deviation
C)  linearity
D)  precision or accuracy

Question 5

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

Accepted Answer

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 6

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

Accepted Answer

A)  shunts
B)  multipliers
C)  current transformers
D)  all of the above

Question 7

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

Accepted Answer

A)  0.4648
B)  975
C)  1700
D)  1100

Question 8

Average resistance of human body is:

Accepted Answer

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

Question 9

Which of the following bridge is frequency sensitive:

Accepted Answer

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

Question 10

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

Accepted Answer

A)  160
B)  400
C)  0.09
D)  360

Question 11

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

Accepted Answer

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 12

Potentiometer is an __ instrument:

Accepted Answer

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

Question 13

In a portable instrument, the controlling torque is provided by

Accepted Answer

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

Question 14

In majority of instruments damping is provided by

Accepted Answer

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

Question 15

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:

Accepted Answer

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 16

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

Accepted Answer

A)  moving
B)  stationary
C)  near its full scale deflection
D)  just staring to move

Question 17

Instrument transformers are

Accepted Answer

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

Question 18

The pointer of an indicating instrument should be

Accepted Answer

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

Question 19

Systematic errors are

Accepted Answer

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

Question 20

Swamping of resistance is used to compensate error due to:

Accepted Answer

A)  stray magnetic field
B)  temperature variations
C)  large supply variations
D)  none of the above

Exam 2: Instrumentation and Electrical Engineering