Overload Switches

Overload Protection for Compressor Motors

An overload switch helps protect an electric motor from sustained excessive current and overheating. It should be selected and set according to the motor full-load current and used as part of a correctly designed control system.

Choose the Correct Overload Switch

How an Overload Switch Works

The overload device monitors motor current and responds when excessive current continues long enough to create a risk of overheating. It interrupts the control circuit or motor supply so the cause can be investigated before the motor is restarted.

• Helps protect motor windings from sustained overcurrent.
• Reduces the risk of overheating and premature motor failure.
• Provides resettable protection after the fault has been corrected.
• Supports safer compressor and machinery operation.
• Must be correctly matched and set for the connected motor.

Why an Overload May Keep Tripping

• Low supply voltage or excessive voltage drop during starting.
• Incorrect overload rating or setting.
• A failed start or run capacitor.
• The compressor is failing to unload before restart.
• A tight pump, motor bearing or other mechanical restriction.
• Incorrect pulley ratio, belt tension or excessive operating pressure.
• Damaged motor windings or poor electrical connections.

Installation and Electrical Safety

• Isolate the compressor from the electrical supply before inspection.
• Confirm the motor data plate and full-load current.
• Check the existing wiring and terminal arrangement before removal.
• Use a correctly rated replacement suitable for the control system.
• Test starting current and running current after installation.
• Installation and fault diagnosis should be completed by a competent person.