Question 1

The voltage appearing across the contacts after opening of the circuit breaker is called______voltage.

Accepted Answer

A)  recovery
B)  surge
C)  operating
D)  arc A

Question 2

The time of closing the cycle, in modern circuit breakers is

Accepted Answer

A)  0.003 sec
B)  0.001 sec
C)  0.01 sec
D)  0.10 sec A

Question 3

Overheating of relay contacts or contact born out is due to

Accepted Answer

A)  slow making and breaking of load circuit contacts
B)  foreign matter on the contact surface
C)  too low contact pressure
D)  all of the above D

Question 4

Large internal faults are protected by

Accepted Answer

A)  merz price percentage differential protection
B)  mho and ohm relays
C)  horn gaps and temperature relays
D)  earth fault and positive sequence relays

Question 5

Interruption of large currents by relay requires

Accepted Answer

A)  arc suppressing blow out coils
B)  wide separation of the opened contacts
C)  high speed opening of contacts
D)  all of the above

Question 6

Resistance grounding is used for voltage between

Accepted Answer

A)  33kVto66kV
B)  HkVto33kV
C)  3.3kVandllkV
D)  none of the above

Question 7

In a circuit breaker the basic problem is to

Accepted Answer

A)  maintain the arc
B)  extinguish the arc
C)  transmit large power
D)  emit the ionizing electrons

Question 8

H.R.C. fuses provide best protection against

Accepted Answer

A)  overload
B)  reverse current
C)  open-circuits
D)  short-circuits

Question 9

Shunt capacitance is neglected while considering

Accepted Answer

A)  short transmission line
B)  medium transmission line
C)  long transmission line
D)  medium and long tr

Question 10

Protective relays are devices that detect abnormal conditions in electrical circuits by measuring

Accepted Answer

A)  current during abnormal condition
B)  voltage during abnormal condition
C)  constantly the electrical quantities which differ during normal and abnormal conditions
D)  none of the above

Question 11

Ungrounded neutral transmission system is not recommended because of system

Accepted Answer

A)  insulation being overstressed due to over voltages
B)  insulation overstress may lead to failure and subsequent phase to phase faults
C)  being inadequately protected against ground fault
D)  all of the above

Question 12

To protect most of the electrical equipment handling low power, the types of relays used are

Accepted Answer

A)  thermocouple
B)  electronic and bimetallic
C)  both (a)  and (b) 
D)  none of the above

Question 13

Which of the following is the least expensive protection for overcurrent is low voltage system ?

Accepted Answer

A)  Rewireable fuse
B)  Isolator
C)  Oil circuit breaker
D)  Air break circuit breaker

Question 14

For the protection of power station buildings against direct strokes the requirements are

Accepted Answer

A)  interception
B)  interception and conduction
C)  interception, conduction and dissipation
D)  interception, conduction, dissipation and reflection

Question 15

Insulation resistance of high voltage circuit breakers is more than

Accepted Answer

A)  1 mega ohms
B)  10 mega ohms
C)  100 mega ohms
D)  500 mega ohms

Question 16

When a transmission line is energized, the wave that propagates on it is

Accepted Answer

A)  current wave only
B)  voltage wave only
C)  both (a)  and (b) 
D)  power factor wave only

Question 17

The delay fuses are used for the protection of ________ .

Accepted Answer

A)  motors
B)  power outlet circuits
C)  fluorescent lamps
D)  light circuits

Question 18

Ionization in circuit breaker is facilitated by

Accepted Answer

A)  high temperature
B)  increase of mean free path
C)  increasing field strength
D)  all of the above

Question 19

A transmission line is protected by

Accepted Answer

A)  inrush protection
B)  distance protection
C)  time graded and current graded over current protection
D)  both (b)  and (c)

Question 20

The reflection co-efficient at the open circuited end of a transmission line.

Accepted Answer

A)  zero
B)  infinity
C)  unity
D)  none of the above

Exam 2: Electrical Protection and Transmission Systems