PTC starter is used to start single phase compressor motor for refrigerator, water coolers, dehumidifiers, air conditioner, and similar refrigeration applications. When power is first applied to the compressor, the PTC element is in low resistance state. Current flows through the PTC element to the start windings, causing a beneficial phase angle shift between start and main windings, and resulting in an increase in the starting torque. After a short period, the PTC temperature rises, and its resistance increases dramatically. This auto-regulation property effectively switch off the start windings after the starting cycle.

PTC Compressor Starter is connected directly across the motor auxiliary winding.