Question 1

When a wave propagates on a transmission line, it suffers reflection several times at

Accepted Answer

A)  tapping
B)  load end
C)  sending end
D)  sending and other end D

Question 2

The interaction between a transmission line and communication line is minimized by

Accepted Answer

A)  transposing transmission as well as communication lines
B)  increasing the height of the trans-mission line tower
C)  increasing the distance between the two lines
D)  all of the above D

Question 3

Which of the following statements is incorrect?

Accepted Answer

A)  Station batteries are used to operate relay only
B)  The lightning arresters are basically surge diverters
C)  An impedance relay has maximum fault current when fault occurs near the relay
D)  A high speed relay has an operation of 1 to 2 cycles A

Question 4

The relay with inverse time characteristic will operate within

Accepted Answer

A)  1.5 sec
B)  5 to 10 sec
C)  5 to 20 sec
D)  20 to 30 sec

Question 5

Discrimination between main and back up protection is provided by the use of relays which are

Accepted Answer

A)  fact
B)  sensitive
C)  slow
D)  none of the above

Question 6

relay is preferred for phase fault on short transmission line.

Accepted Answer

A)  Induction type
B)  Reactance
C)  Impedance
D)  None of the above

Question 7

To reduce short circuit fault currents are used.

Accepted Answer

A)  reactors
B)  resistors
C)  capacitors
D)  none of the above

Question 8

A.C. network analyser is used to solve problems of

Accepted Answer

A)  load flow
B)  load flow and short-circuit
C)  load flow and stability
D)  load flow, short-circuit and stability

Question 9

Series reactors should have

Accepted Answer

A)  low resistance
B)  high resistance
C)  low impedance
D)  high impedance

Question 10

relays are used for phase faults on long line.

Accepted Answer

A)  Impedance
B)  Reactance
C)  Either of the above
D)  None of the above

Question 11

The under voltage relay can be used for

Accepted Answer

A)  generators
B)  busbars
C)  transformers
D)  all of the above

Question 12

Short-circuit currents are due to

Accepted Answer

A)  single phase to ground faults
B)  phase to phase faults
C)  two phase to ground faults
D)  any of these

Question 13

The single phasing relays are used for the protection of

Accepted Answer

A)  single phase motors only
B)  two phase motors only
C)  two single phase motors running in parallel
D)  three phase motors

Question 14

Distance relays are generally

Accepted Answer

A)  split-phase relays
B)  reactance relays
C)  impedance relays
D)  none of the above

Question 15

The short circuit in any winding of the transformer is the result of

Accepted Answer

A)  mechanical vibration
B)  insulation failure
C)  loose connection
D)  impulse voltage

Question 16

For which of the following ratings of the transformer differential protection is recommended ?

Accepted Answer

A)  above 30 kVA.
B)  equal to and above 5 MVA
C)  equal to and above 25 MVA
D)  none of the above

Question 17

A _______ is used to measure the stator % winding temperature of the generator.

Accepted Answer

A)  thermocouple
B)  pyrometer
C)  resistance thermometer
D)  thermometer

Question 18

Induction cup relay is operated due to changes in

Accepted Answer

A)  current
B)  voltage
C)  impedance
D)  all of the above

Question 19

Bus coupler is very essential in arrangement

Accepted Answer

A)  single bus
B)  double bus, double breaker
C)  main and transfer bus
D)  all of the above

Question 20

The line insulation is the insulation level of the station equipment.

Accepted Answer

A)  less than
B)  same as
C)  more than
D)  not directly related with

Exam 3: Electrical Substation Equipment and Protection Systems