Kondensaattorikäynnistysmoottorit

Kondensaattorikäynnistysmoottorit, or capacitor-start motors, are a type of single-phase induction motor designed for applications requiring higher starting torque than that provided by split-phase motors. They achieve this increased torque through the use of a capacitor connected in series with the auxiliary starting winding. This capacitor is typically a high-value electrolytic type.

When the motor starts, both the main winding and the starting winding are energized. The capacitor in the starting circuit creates a phase shift between the current in the main winding and the starting winding. This phase shift results in a rotating magnetic field within the stator, which then induces a current in the rotor and generates torque, initiating rotation. The capacitor is usually switched out of the circuit once the motor reaches approximately 75-80% of its operating speed by a centrifugal switch or a current-sensing relay.

This design makes capacitor-start motors suitable for loads that are difficult to start, such as compressors, pumps, and heavy machinery. They offer a good balance between starting performance and cost compared to other single-phase motor types. However, the presence of the capacitor and the switching mechanism adds complexity and potential points of failure. The motor's efficiency is generally good once it is running on the main winding alone.