## PSC Junior Instructor – Electrician Solved Paper 2015 – Part 3

Question 51:-_________ is the measure of how much potential difference the insulation layer can withstand without breaking down.
A:-Insulation resistance
B:-Breakdown voltage
C:-Resistance
D:-Dielectric strength

Question 52:-The light output of Tin oxide Sodium lamps is in the order of
A:-50 lumens/watt
B:-45 lumens/watt
C:-75 lumens/watt
D:-150 lumens/watt

Question 53:-The torque of a three phase induction motor is proportional to
A:-square root of applied voltage
B:-applied voltage
C:-square of applied voltage
D:-half of applied voltage

Question 54:-Tap changing transformers are used for
A:-stepping up the voltage
B:-stepping down the voltage
C:-both stepping up and stepping down the voltage
D:-supplying low current for instruments

Question 55:-Which Dc motor have negligible effect on speed with increase in torque?
A:-DC differential compound motor
B:-DC cumulative compound motor
C:-DC series motor
D:-DC shunt motor

Question 56:-In a pure inductive AC circuit, the average true power is equal to
A:-V x I watts
B:-Zero watts
C:-Square of current multiplied by reactance Watts
D:-V x I volt amperes

Question 57:-The part of an instrument which helps in leading in and leading out the current to the moving coil is
A:-the spindle
B:-the copper or aluminium disc
C:-jewel bearing
D:-control spring

Question 58:-An outside micrometer can measure thickness and outside diameters to an accuracy of
A:-±0.1mm
B:-±0.5mm
C:-±0.001mm
D:-±0.01mm

Question 59:-When a secondary battery is charged at 2% to 3% of normal rate for a long period, it is known as
A:-boost charge
B:-trickle charge
C:-freshening charge
D:-initial charge

Question 60:-Double squirrel cage induction motors are used where ________ torque is essential.
A:-high starting torque
B:-low starting torque
C:-low running torque
D:-high running torque

Question 61:-Which one of the following wiring circuit is not in accordance with IE rules?
A:-Corridor wiring
B:-Tunnel wiring
C:-Godown wiring
D:-Bank wiring

Question 62:-The distance between the two active sides of a coil under adjacent dissimilar poles is called
A:-coil pitch
B:-winding pitch
C:-pole pitch
D:-pitch factor

Question 63:-For the blocked rotor test of a 3 phase induction motor, the supply voltage should be limited to less than _______ percentage of rated voltage.
A:-5%
B:-10%
C:-3%
D:-20%

Question 64:-The amount of heat required to increase the temperature of one kilogram of water through 1°C is
A:-3187 joule
B:-4187 joule
C:-4187 calorie
D:-3187 calorie

Question 65:-Admittance is the reciprocal of
A:-resistancve
B:-conductance
C:-reactance
D:-impedance

Question 66:-The damping winding in a synchronous motor is generally used
A:-to provide starting torque only
B:-to reduce noise level
C:-to prevent hunting and to provide the starting torque
D:-to reduce eddy currents

Question 67:-Voltage dependent resistors are used as
A:-as current stabilisers
B:-as heating elements
C:-to suppress surges
D:-for inductive circuits

Question 68:-In a DC generator, brush shifting is done to
A:-alter the inter pole flux
B:-alter the main field flux
C:-neutralise the cross magnetising effect
D:-neutralise the demagnetising effect

Question 69:-To control a lamp from 4 positions, how many switches are required?
A:-4 two-way switcges
B:-4 intermediate switches
C:-3 two-way switches and one intermediate switch
D:-2 intermediate switches and 2 two-way switches

Question 70:-The fusing factor for HRC fuse is
A:-2.0
B:-1.7
C:-1.4
D:-1.1

Question 71:-Low and medium voltage underground cables should be laid at a depth of _______ from the ground surface to the top of the cable.
A:-0.75m
B:-0.9m
C:-1.0m
D:-1.05m

Question 72:-For low and medium voltage overhead lines, the minimum clearance above ground, which is erected across a street, shall not be less than
A:-5.791m
B:-6.096m
C:-5.486m
D:-4.572m

Question 73:-In capacitor start, capacitor run motors, the capacitors used are
A:-both capacitors are of same value
B:-one larger value capacitor of oil filled type and a smaller value capacitor of electrolytic type.
C:-one larger value capacitor of electrolytic type and a smaller value capacitor of oil filled type.
D:-both capacitors are of electrolytic type.

Question 74:-While erecting a pole, the depth of pit below the ground level, in normal soil should be about _________ of the length of the pole.
A:-1/6
B:-1/5
C:-1/4
D:-1/7

Question 75:-In an AC operated relay, the purpose of shading coil placed near the tip of magnetic pole face is to
A:-eliminate chatter
B:-eliminate humming
C:-to reduce eddy current
D:-to reduce hysteresis loss