A Y-connected, 3-phase, 50 Hz, 6-pole, slip ring induction motor has following data: Rating: 400 V, 50kW, 960rpm Rs=0.08 Ω, Rr'=0.1 Ω, Xs=Xr'=0.3 Ω Moment of inertia=10Kg·m2 Motor is to be stopped from its no load speed under reverse voltage braking operation. Find the value of external resistance to be inserted in rotor circuit so that the braking process will take minimum time. Also calculate braking time. With the rotor resistance as calculated in (i) find energy loss in the motor..

A Y-connected, 3-phase, 50 Hz, 6-pole, slip ring induction motor has following data: Rating: 400 V, 50kW, 960rpm Rs=0.08 Ω, Rr'=0.1 Ω, Xs=Xr'=0.3 Ω Moment of inertia=10Kg·m2 Motor is to be stopped from its no load speed under reverse voltage braking operation. Find the value of external resistance to be inserted in rotor circuit so that the braking process will take minimum time. Also calculate braking time. With the rotor resistance as calculated in (i) find energy loss in the motor..

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter32: Three-phase Motors

Section: Chapter Questions

Problem 6RQ: Name three factors that determine the torque produced by an induction motor.

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Concept explainers

Types of Braking

A brake is a mechanical device that absorbs energy from a moving system and inhibits its motion. It helps to slow or stop a moving vehicle, axle, wheel, etc. The braking system uses friction between two types of surfaces that are pressed together that convert kinetic energy into heat energy. For instance, we know that in the case of regenerative braking, the brakes convert energy into electrical energy which can be used for later use. The conversion of kinetic heat energy into potential energy is stored in the form of pressurized oil or air. In the brake disc, oil, or fin, the eddy current brakes convert kinetic energy into the electric current with the help of a magnetic field which is converted into heat.Generally, such braking systems apply to the moving axles of wheels. They may also take other forms like moving fluids' surface. In the case of drag racing cars, both wheel brakes are used whereas in parachute or airplanes, both wheel brakes or drag flaps raised in to the air are used.

Question

A Y-connected, 3-phase, 50 Hz, 6-pole, slip ring induction motor has following data:

Rating: 400 V, 50kW, 960rpm

Rs=0.08 Ω, Rr'=0.1 Ω, Xs=Xr'=0.3 Ω

Moment of inertia=10Kg·m2

Motor is to be stopped from its no load speed under reverse voltage braking operation.

Find the value of external resistance to be inserted in rotor circuit so that the braking process will take minimum time. Also calculate braking time.
With the rotor resistance as calculated in (i) find energy loss in the motor..

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