WorksheetsProtection and Switchgear Quiz 3
Total questions: 10
Worksheet time: 5mins
What is the major cause of the failure of the circuit breaker?
Trip circuit open
Trip latch defective
Spring defective
All of these
For a high speed circuit breaker what will the total clearing time?
Few minutes
Few seconds
1 to 2 cycles
5 to 20 cycles
Circuit breakers usually operate under
Steady short circuit current
Sub transient state of short circuit current
Transient state of short circuit current
None of these
SF6 is which type of gas?
Electro positive
Electro negative
Both (a) and (b)
None of these
What is the purpose of back up protection?
To increase the speed
To increase the reach
To leave no blind spot
To guard against failure of primary
In a circuit breaker the contact space is ionised by what?
Thermal conduction from the contact surface
Thermal emission from the contact surface
Thermal ionisation of gas
All of above
Which of the following should have low value for the contacts and their material?
Thermal capacity
Contact resistance
Thermal conductivity
None of above
How is the initiation of electric arc at the instant of contact separation caused?
Field emission of electrons
Thermionic emission of electrons
Both (a) and (b)
None of these
The arc resistance depends on which among the following factors?
Cross section of the arc
Length of the arc
Degree of ionization
All of the above
The rating of the circuit breaker is usually determined on the basis of _______ fault.
Symmetrical
Line to line
Single line to ground
Double line to ground
