Q.1
Oil switches are employed for
  • low currents circuits
  • low voltages circuits
  • high voltages and large currents circuits
  • all circuits
Q.2
Which of the following circuit breakers has high reliability and minimum maintenance ?
  • Air blast circuit breakers
  • Circuit breaker with SF6 gas
  • Vacuum circuit breakers
  • Oil circuit breakers
Q.3
By which of the following methods major portion of the heat generated in a H.R.C. fuse is dissipated ?
  • Radiation
  • Convection
  • Conduction
  • All of the above
Q.4
Relays are used for phase faults on long line.
  • Impedance
  • Reactance
  • Either of the above
  • None of the above
Q.5
Relays can be designed to respond to changes in
  • resistance, reactance or impedance
  • voltage and current
  • light intensity
  • temperature
  • all above
Q.6
Fault diverters are basically
  • fuses
  • relays
  • fast switches
  • circuit breakers
Q.7
Ionization in circuit breaker is facilitated by
  • high temperature
  • increase of mean free path
  • increasing field strength
  • all of the above
Q.8
On which of the following effects of electric current a fuse operates?
  • Photoelectric effect
  • Electrostatic effect
  • Heating effect
  • Magnetic effect
Q.9
In order that current should flow without causing excessive heating or voltage drop, the relay contacts should
  • Have low contact resistance
  • Be clean and smooth
  • Be of sufficient size and proper shape
  • Have all above properties
Q.10
Shunt capacitance is neglected while considering
  • short transmission line
  • medium transmission line
  • long transmission line
  • medium and long transmission lines
Q.11
Which of the following parameter can be neglected for a short line?
  • Inductance
  • Capacitance
  • Resistance
  • Reactance
Q.12
Induction cup relay is operated due to changes in
  • current
  • voltage
  • impedance
  • all of the above
Q.13
Ungrounded neutral transmission system is not recommended because of system
  • insulation being overstressed due to over voltages
  • insulation overstress may lead to failure and subsequent phase to phase faults
  • being inadequately protected against ground fault
  • all of the above
Q.14
The delay fuses are used for the protection of ________ .
  • motors
  • power outlet circuits
  • fluorescent lamps
  • light circuits
Q.15
Overload relays are of type.
  • induction
  • solid state
  • thermal
  • electromagnetic
  • E. all above
Q.16
A balanced 3-phase system consists of
  • zero sequence currents only
  • positive sequence currents only
  • negative and zero sequence currents
  • zero, negative and positive sequence currents
Q.17
The line insulation is the insulation level of the station equipment.
  • less than
  • same as
  • more than
  • proportional to
  • E. not directly related with
Q.18
Burden of a protective relay is the power
  • required to operate the circuit breaker
  • absorbed by the circuit of relay
  • developed by the relay circuit
  • none of the above
Q.19
What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?
  • Zero
  • Unity
  • Infinity
  • None of the above
Q.20
The torque produced in induction type relay (shaded pole structure) is
  • inversely proportional to the current
  • inversely proportional to the square of the current
  • proportional to the current
  • proportional to square of the current
Q.21
The material used for fuse must have
  • low melting point and high specific resistance
  • low melting point and -low specific resistance
  • high melting point and low specific resistance
  • low melting point and any specific resistance
Q.22
The voltage appearing across the contacts after opening of the circuit breaker is called______voltage.
  • recovery
  • surge
  • operating
  • arc
  • none of the above
Q.23
Admittance relay is _______ relay.
  • impedance
  • directional
  • non-directional
  • none of the above
Q.24
Directional relays are based on flow of
  • power
  • current
  • voltage wave
  • all of the above
Q.25
Protection by fuses is generally not used beyond
  • 20 A
  • 50 A
  • 100 A
  • 200 A
Q.26
A fuse is connected
  • in series with circuit
  • in parallel with circuit
  • either in series or in parallel with circuit
  • none of the above
Q.27
Arc in a circuit behaves as
  • a capackive reactance
  • an inductive reactance
  • a resistance increasing with voltage rise across the arc
  • a resistance decreasing with voltage rise across the arc
Q.28
The inverse definite mean time relays are used for over current and earth fault protection of transformer against
  • heavy loads
  • internal short-circuits
  • external short-circuits
  • all of the above
Q.29
The relay with inverse time characteristic will operate within
  • 1.5 sec
  • 5 to 10 sec
  • 5 to 20 sec
  • 20 to 30 sec
  • E. none of the above
Q.30
Thermal overload relays are used to protect the motor against over current due to
  • short-circuits
  • heavy loads
  • grounds
  • all of the above
0 h : 0 m : 1 s