HUNTING IN MOTOR

                                     

Causes of hunting motor or generator? 

1. Sudden removed the load from the motor or generator.

 

2. Sudden change in the field winding current.

3. Cyclic variation of the load torque on the motor and generator.

4. Faulting occurring in the power system which the generator supplies.

Effects of hunting on the generator and motor?

1. motor or generator loses your synchronism. 

2. hunting increases the possibility of resonance.

3. Large mechanical torque may develop in the rotor shaft.

4. power losses in motor and generator increase and temperatures of the machine rise.

5. hunting can cause variations of the supply voltage producing undesirable lamp flickers.

Reducing methods of hunting:-

Two methods can be used to reduce the hunting effect. written below-

Using the damper winding:-

damper winding situated in the slot of the pole face in salient pole machines. damper winding made by aluminum and copper with low resistance.

 

when the sudden rotor speed is chanced by the Lenz law an electromotive force(EMF) produces in damper winding. damper winding back (EMF) opposes the change of rotor speed.

Thus the speed of the rotor remains unchanged.

Advantage

1. some number of turns used.

2. clean and weightless.

3. immediate effectiveness is shown.

4. this method is used on large scale. 

 Using the heavy flywheel:-   

This method is taken from physics law conservation of momentum.

in this method, heavy mass is connected with prime mover. so that inertia of prime mover increased. so that motor moves at constant speeds.