1. Damping of Oscillations: The primary purpose of damper windings is to damp out electrical oscillations that may occur in the alternator's electrical circuits. These oscillations can be caused by sudden changes in load or faults in the power system. The damper windings act as a closed circuit that provides a path for the oscillating currents to flow, dissipating them as heat. This helps to stabilize the alternator's output voltage and prevent potential damage to the machine.
2. Reduction of Hunting: Hunting is a phenomenon in synchronous machines, including alternators, where the rotor tends to oscillate about its equilibrium position due to the interaction between the rotating magnetic fields. Damper windings help to reduce hunting by providing additional damping to the rotor's motion. The damper winding acts as a squirrel-cage induction winding, creating a damping torque that opposes the rotor's oscillations and brings it back to its stable operating position.
Damper windings are typically embedded in slots on the rotor's surface, parallel to the field winding slots. They consist of copper or aluminum bars or conductors connected together at their ends to form a closed circuit. The damper winding is designed to have a low resistance and high reactance, allowing the oscillating currents to flow easily while minimizing energy losses.
The effective design and placement of damper windings are crucial for the stable operation of alternators. Proper damping ensures that the machine responds quickly to load changes, maintains voltage stability, and minimizes the impact of disturbances on the power system.
