What it means
The main motor overload relay has tripped or the controller has detected the corresponding overload condition.
The compressor is protected from continued operation while the motor overload condition exists.
Likely causes
- Main motor overload relay tripped
- Incorrect compressor configuration or pressure setting
- Low line voltage
- Underlying motor, starter, electrical or mechanical load problem
Operator-safe first checks
- Do not keep resetting the overload after repeated trips.
- Record load pressure, other alarms and whether the trip occurred at start or while loaded.
- Escalate electrical checks to qualified personnel.
Trained maintenance / service checks
- After the overload element cools, determine why it tripped before resetting.
- Verify compressor configuration and load-pressure setting.
- Measure line voltage and diagnose starter, motor and mechanical load as required.
Can the compressor keep running?
No. A motor overload is a protective trip; repeated resets can damage equipment or create an electrical hazard.
Source confidence
OEM VERIFIED
Sullair directs service personnel to the overload relay, compressor configuration, load pressure and line voltage.
Source: Sullair STS Controller User Manual, part 02250241-178 R01. Referenced manual page(s): 33.