Correct option is A
· Hunting is a phenomenon that occurs in synchronous machines, both synchronous motors and synchronous generators.
· It refers to the oscillation or fluctuation of the rotor around its synchronous speed. This oscillation is caused by sudden changes in load, voltage fluctuations, or disturbances in the power system.
· Hunting can lead to instability and may cause mechanical stresses in the machine, which can be harmful if not controlled. To mitigate hunting, dampers or damper windings are often used in synchronous machines.
CAUSES OF HUNTING:
· Sudden changes of load
· Faults occurring in the system which the generator supplies
· Sudden changes in the field current
· Cyclic variations of the load torque.
EFFECTS OF HUNTING:
· It can lead to loss of synchronism.
· It can cause variations of the supply voltage producing undesirable lamp flicker.
· It increases the possibility of resonance. If the frequency of the torque component becomes equal to that of the transient oscillations of the synchronous machine, resonance may take place.
· Large mechanical stresses may develop in the rotor shaft.
· The machine losses increase and the temperature of the machine rises.
