# GAIL Placement Paper- Technical questions from previous years

## GAIL Placement Paper- Technical questions from previous years

Some of the questions observed in the technical section of GAIL’s written test paper are:

• What will be the volume of EMF, if a 4 pole lap wound DC shunt motor rotates at the speed of 1500 rpm with a flux of 0.4 mWB and the total numbers of conductors are 1000?

a. 0.1 volts
b. 10 volts
c. 100 volts
d. 1 volts

• What does a ceiling fan uses for its working?

a. Universal motor
b. Split – phase motor
c. Capacitor start motor
d. Capacitor start and capacitor run motor

• In a 3 phase synchronous motor

a. The speed of stator MMF is synchronous speed while that of rotor MMF is zero
b. The speed of stator MMF is always more than that of rotor MMF
c. The speed of stator MMF is always less than that of rotor MMF
d. Rotor and stator MMF are stationary with respect to each other

• How many pole of motor shall be there in a 50 Hz – 3 phase induction motor which has a full load of speed at 1440 r.p.m

a. 12
b. 8
c. 4
d. 6

• Assuming a 100% efficiency of a 1:5 step – up transformer has 120V across the primary and 600 ohms resistance across the secondary. Find the primary current equals?

a. 10 Amps
b. 5 Amps
c. 20 Amps
d. 0.2 Amps

• What shall be the frequency of rotor induced emf in a slip of the induction machine is 0.02 and the stator supply frequency is 50 HZ?

a. 2500Hz
b. 10Hz
c. 1 Hz
d. 50 Hz

• A 3 stack stepper motor with 12 numbers of rotor teeth has a step angle of

a. 8°
b. 24°
c. 12°
d. 10°

• What will you change to control the temperature of resistance furnaces?

a. Circuit configuration
b. Applied voltage
c. Number of heating elements
d. All of the above

• A single phase Hysteresis motor can run at

a. Synchronous and super synchronous speed
b. Sub synchronous speed only
c. Synchronous speed only
d. Synchronous and sub synchronous speed

• Oil – filled cable has a working stress of _________ kV/mm

a. 15
b. 12
c. 13
d. 10

• Which type of drive motor is used in a mixer – grinder?

a. Induction motor
b. Universal motor
c. DC motor
d. Synchronous motor

• How will an RC differentiator act?

a. Band – pass filter
b. Low – pass filter
c. Band – stop filter
d. High – pass filter

• What shall be the rotor frequency of a 3 phase 1000 RPM 6 pole induction motor with a slip of 0.04?

a. 6 Hz
b. 4 Hz
c. 2 Hz
d. 8 Hz

• Which of the following capacitor is polarized?

a. Electrolytic
b. Mica
c. Plastic – film
d. Ceramic

• A balanced 3 – phase, 50 Hz voltage is applied to a 3 phase, 4 pole induction motor, when the motor is delivering rated output the slip is found to be 0.05. What will be the speed of the rotor m.m.f relative to the rotor structure?

a. 25 r.p.m
b. 1500 r.p.m
c. 75 r.p.m
d. 1425 r.p.m

• From the below mentioned option, on which is the efficiency of a transformer dependent?

a. Stray losses
b. Di – electric losses
c. Core losses
d. Copper losses

• The synchronous speed for a 3 phase 6 pole inductions motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% shall be

a. 1500 rpm
b. 1690 rpm
c. 1750 rpm
d. 1710 rpm

• What is reduced when we laminate the armature of a SC machine?

a. Hysteresis loss
b. Friction and windage loss
c. Eddy current loss
d. Copper loss