What type of machinery typically utilizes a start capacitor?

Single-phase induction motors commonly utilize a start capacitor to enhance their starting torque. When power is applied to a single-phase motor, it does not naturally generate a rotating magnetic field, which is essential for starting. A start capacitor temporarily stores electrical energy and releases it to create a phase shift in the voltage supplied to the motor. This phase shift helps establish a rotating magnetic field, enabling the motor to start. Once the motor reaches a certain speed, typically around 70-80% of its full speed, a centrifugal switch or electronic relay disconnects the capacitor from the circuit, allowing the motor to operate solely on its running winding.

In contrast, heat pumps and central air conditioning units don't typically require start capacitors; instead, they often utilize different types of strategies for starting like built-in relays or other methods suited for their operational requirements. Three-phase generators usually do not use start capacitors, as they inherently produce a rotating magnetic field and do not experience the starting torque limitations faced by single-phase motors.