Important interview questions for an induction motor?

INDUCTION MOTOR

1.What is an induction motor?

an alternating current motor in which torque is produced by the reaction between a varying magnetic field generated in the stator and the current induced in the coils of the rotor. It is also called as asynchronous motor.

2.what are the types of induction motor?

Single phase induction motor

a) split phase induction motor

b) capacitor start induction motor

c) capacitor start capacitor run induction motor

d) shaded pole induction motor

Three phase induction motor

a) squirrel cage induction motor

b) slip ring induction motor

3.what is slip in an induction motor?

It is the difference between the flux speed(Ns) and rotor speed(N).

Speed of the rotor of an induction motor is always less than its synchronous speed.

%slip = (Ns-N) *100/Ns.

4.what are the methods of measuring slip?

a) measurement of rotor speed

b) measurement of rotor frequency

c) stroboscopic method

5.what are the method of speed control in three phase induction motor?

a)control from stator side:

Changing the supply frequency

Changing the supply voltage

Changing the number of stator poles

b) control from rotor side:

Injecting resistance in rotor circuit

Injecting EMFs in the rotor circuit

Various ways of cascade connection

6.what are the test of induction motor?

a)No load test

b) locked rotor test

c) break down torque load performance test

d) temperature test

e) determination of efficiency test

f) stray load loss test

7.what are the starters used for starting induction motor?

a) direct online starter

b) star delta starter

c) auto transformer starter

d) resistance starter

e) series reactance starter

Comments

Star Delta starter working principles, control circuit, components, advantages and disadvantages

Star delta starter working principle theory There are many different starting methods are used to start a three-phase induction motor like Star delta starter. One of them, popular and cheapest is a Direct online starter. But its use limited for smaller HP motor, to start higher rating 3 phase motors star-delta starter is used. Star-delta starter is useful where all six terminals of the motor are accessible. we will discuss star delta starter working principle with help of power and control diagram, Theory, connection wiring diagram, parts like contactor, mcb, fuses, a timer circuit, overload relay. Star-Delta starter is the simplest starting method for reducing the inrush starting current of Induction motor. The starter can be used with all squirrel-cage induction motors that are delta-connected for normal operation. The reduction of the high motor current causes a reduction of the starting torque of the motor. Star-delta starting is therefore especially suitable for...

How to do Installation and termination of Electrical cables(HV, MV, LV)?

How to do Installation and Termination of Electrical cables(HV, MV, LV) : 1.Material : All wires and cables to be examined prior to installation. No wire or cable with bruised, cut or abraded insulation, or wire that does not pass a continuity test shall be used. 2.Tools and equipment : Truck, crane, cable drum jacks, cable drum shaft, cable socks, cable rollers, cable cutter, hydraulic crimping tools, hand crimping tools, scaffolding with wheels, ladders, torque wrench, box spanner set, ring spanner set, open end spanner set, screw driver, hack saw frame, measuring tape, drilling machines, holesaw cutter, cutting pliers. 3.Preparation : Cables shall be identified with regard to type, size, length etc. And shall be inspected for any physical damage. The cable shall be free from any damages and the ends sealed with caps to prevent the ingress of water during transportation or storage. 4.Installation : All cable shall be megger tested prior to pulling cable. Prior to com...

What is the purpose of automatic transfer switch (ATS)?

What is the Purpose of a Transfer Switch ? A automatic transfer switch (ATS) is a gadget that transfer a force supply from its essential source consequently to a reinforcement generator when it detects a disappointment or blackout happening in the essential source until utility force is reestablished. The ATS is associated with both essential and reinforcement power sources, and fills in as a delegate between the force sources and your structure or hardware, going about as an electrical transfer. An ATS can likewise go about as a repetitive, rack-mounted force supply for hardware that is associated with a force source with just one line. How does an transfer switch work? The main breaker in the transfer switch switches the force source from your utility capacity to a backup generator. The structure can't be associated with both the generator and utility force simultaneously. The main breaker moves power from one source to the next. This forestalls the gene...

Electrical learn easily

Search This Blog