Locked rotor amps. A compressor's LRA is typically around five to six times its rated load amps. Seeing LRA for more than a second or two means the compressor is not starting: a failed capacitor, a stuck mechanism, high unequalized pressures or a bad winding. The internal overload then trips, and the cycle repeats every few minutes until someone notices.
Clamp shows 112 amps for three seconds and then the overload kicks, that's LRA, check the cap before you condemn the compressor.
Also heard as
- locked rotor amps
- locked rotor current
Related terms
Cap
Short for capacitor, the part that gives compressor and fan motors the phase shift they need to start and run.
Hard start kit
An add-on start capacitor and relay that gives a struggling compressor extra torque to start.
Compressor
The pump that raises refrigerant vapor from evaporator pressure to condenser pressure and keeps it circulating.
Short cycling
A compressor or system turning on and off too often, with run times too short to reach steady operation.