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Indian Oil Corporation Limited

IOCL Management Trainee

Electrical Engineering Technical Questions

Q.1 The two windings of a transformer is

• conductively linked.
• inductively linked.
• not linked at all.
• electrically linked.

Q.2 A salient pole synchronous motor is running at no load. Its field current is switched off. The motor will

• come to stop.
• continue to run at synchronous speed.
• continue to run at a speed slightly more than the synchronous speed.
• continue to run at a speed slightly less than the synchronous speed.

Q.3 The d.c. series motor should always be started with load because

• at no load, it will rotate at dangerously high speed.
• it will fail to start.
• it will not develop high starting torque.
• all are true.

Q.4 The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is about

• 50 Hz.
• 20 Hz.
• 2 Hz.
• Zero.

Q.5 In a stepper motor the angular displacement

• can be precisely controlled.
• it cannot be readily interfaced with micro computer based controller.
• the angular displacement cannot be precisely controlled.
• it cannot be used for positioning of work tables and tools in NC machines.

Q.6 The power factor of a squirrel cage induction motor is

• low at light load only.
• low at heavy load only.
• low at light and heavy load both.
• low at rated load only.

Q.7 The generation voltage is usually

• between 11 KV and 33 KV.
• between 132 KV and 400 KV.
• between 400 KV and 700 KV.
• None of the above.

Q.8 When a synchronous motor is running at synchronous speed, the damper winding produces

• damping torque.
• eddy current torque.
• torque aiding the developed torque.
• no torque.

Q.9 If a transformer primary is energised from a square wave voltage source, its output voltage will be

• A square wave.
• A sine wave.
• A triangular wave.
• A pulse wave.

Q.10 In a d.c. series motor the electromagnetic torque developed is proportional to

• (A)1a
• (B)12a
• (C)1/1a
• (D)1/12a

Q.11 In a 3 – phase induction motor running at slip ‘s’ the mechanical power developed in terms of air gap power Pg is

• (A)(s-1)Pg
• (B)Pg/1-S
• (C)1-SPg
• (D)S.Pg.

Q.12.In a 3 – phase induction motor the maximum torque

• is proportional to rotor resistance
• does not depend on
• is proportional to
• is proportional to

Q.13.In a d.c. machine, the armature mmf is

• stationary w.r.t. armature.
• rotating w.r.t. field.
• stationary w.r.t. field.
• rotating w.r.t. brushes.

Q.14.In a transformer the voltage regulation will be zero when it operates at

• unity p.f.
• leading p.f.
• lagging p.f.
• zero p.f. leading.

Q.15 The maximum power in cylindrical and salient pole machines is obtained respectively at load angles of

Q.16 The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be

• 3.6 V.
• 2.5 V.
• 3.0 V.
• 6.0 V.

Q.17 The emf induced in the primary of a transformer

• is in phase with the flux.
• lags behind the flux by 90 degree.
• leads the flux by 90 degree.
• is in phase opposition to that of flux.

Q.18 The relative speed between the magnetic fields of stator and rotor under steady state operation is zero for a

• dc machine.
• 3 phase induction machine.
• synchronous machine.
• single phase induction machine.
• all are correct

Q.19 The current from the stator of an alternator is taken out to the external load circuit through

• slip rings.
• commutator segments.
• solid connections.
• carbon brushes.

Q.20 A motor which can conveniently be operated at lagging as well as leading power factors is the

• squirrel cage induction motor.
• wound rotor induction motor.
• synchronous motor.
• DC shunt motor.

Q.21 A hysteresis motor

• is not a self-starting motor.
• is a constant speed motor.
• needs dc excitation.
• can not be run in reverse speed.

Q.22.The most suitable servomotor for low power applications is

• a dc series motor.
• a dc shunt motor.
• an ac two-phase induction motor.
• an ac series motor.

Q.23 The size of a conductor used in power cables depends on the

• operating voltage.
• power factor.
• current to be carried.
• type of insulation used.

Q.24 Out of the following methods of heating the one which is independent of supply frequency is

• electric arc heating
• induction heating
• electric resistance heating
• dielectric heating

Q.25.A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be

• 4.5%.
• less than 4.5%.
• more than 4.5%.
• 4.5% or more than 4.5%.

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