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The torque produced in induction type relay (shaded pole structure) is inversely proportional to the square of the current.

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Description : With a neat sketch give the working of shaded pole induction motor.

Last Answer : Explanation: It has squirrel cage rotor and salient pole stator. The stator poles are shaded partially by short circuited conductor band to create the phase difference between the fluxes emerging from shaded ... rotating magnetic field in the air-gap and torque is exerted on the squirrel cage rotor.

Description : In the induction type directional over current relay, when a short-circuit occurs in the circuit (A) power flows in reverse direction (B) power flows in normal direction (C) directional power element does not operate (D) over current element is not energized

Last Answer : In the induction type directional over current relay, when a short-circuit occurs in the circuit power flows in reverse direction

Last Answer : In a shaded pole single-phase motor, the revolving field is produced by the use of shading coils.

Description : State two applications of 1) Shaded pole motor 2) Universal motor

Last Answer : (i)Applications of Shaded pole motor: 1. Small fans 2. Toy motors 3. Hair dryers 4. Ventilators 5. Electric clocks 6. Record players 7. Motorized valves 8. Gramophones 9. Photocopying ... 5. Portable Drilling Machines 6. Electric Shavers 7. Mechanical computing Machines 8. Machine Tools etc.

Last Answer : Locked rotor current of a shaded pole motor is slightly more than full load current.

Last Answer : The shaded pole motor is used for low starting torque.

Last Answer : In case of a shaded pole motor the direction of rotation of the motor is from main pole to shaded pole.

Last Answer : A shaded pole motor can be used for toys, hair dryers, circulators etc.

Last Answer : The range of efficiency for shaded pole motors is 5% to 35%.

Last Answer : In a shaded pole motor, the shading coil usually consist of a single turn of heavy copper wire which is short-circuited and carries only induced current.

Last Answer : Induction cup relay is operated due to changes in current, voltage, impedance.

Description : In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high ... the outer high resistance winding. (D) Large current flows through the inner low resistance winding.

Last Answer : In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.

Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be

Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m

Description : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down

Last Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque

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Description : State the function and shape of following parts used in induction type energy meter: i) Series magnet ii) Shunt magnet iii) Al disc iv) Brake magnet

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Last Answer : Operating Principal:- The disc is placed between the two-flux due to pressure coil and flux due to current coil, which will set up torque on the disc which is proportional to power causing the ... is proportional to voltage, the second carries a current coil so its flux is proportional to current.

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Description : An induction type energy meter is found to run fast. Correction for this error can be made by  (A) Over-load compensation. (B) Voltage compensation. (C) Moving the brake magnet away from the centre of the disc. (D) Moving the brake magnet towards the centre of the disc.

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Last Answer : Induction type single phase energy meters measure electric energy in kWh.

Description : The most efficient torque — producing actuating structure for induction — type relay is:

Last Answer : The most efficient torque — producing actuating structure for induction — type relay is: induction-cup structure

Description : A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60

Last Answer : 0

Description : The purpose of the restraining coil in a biased differential relay is  (A) To reduce CT saturation during fault.  (B) To increase the sensitivity of the relay.  (C) To match the transformation ratio.  (D) To limit the spill current through the relay during heavy external fault.

Last Answer : d

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Description : What is the difference between relay and contactor?

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Last Answer : A negative sequence relay is used for protection of Generator 

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Last Answer : The relay with inverse time characteristic will operate within 5 to 10 sec.

Last Answer : The under voltage relay can be used for generators, busbars, transformers, motors.

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Last Answer : Relay working like contact it is noise less 

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Description : The torque produced in wattmeter is proportional to

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