How a compressor motor starts affects inrush current, component stress and energy use. The right start method protects the electrical supply and extends motor life.
Direct and Star-Delta Start
- Direct start draws a high inrush current.
- Star-delta reduces starting current by starting in star then switching to delta.
- Both run at fixed speed after starting.
Soft Start
- Ramps voltage to limit inrush current.
- Reduces mechanical shock on the drivetrain.
- Still runs at fixed speed once running.
Variable Speed Drive
- Varies motor speed to match air demand.
- Best part-load efficiency and soft starting.
- Higher cost but fastest energy payback in variable load.
Which start method is best?
For energy savings at variable load, VSD is best. For fixed-speed machines, soft start or star-delta protects the supply.
Talk to an Engineer
Contact Panrui with your flow, pressure and air quality requirements to get a recommendation and factory quote for your project.