IEC (the International Electrotechnical Commission) uses eight duty cycle designations to describe electrical motors operating conditions:
|The motor works at a constant load for enough time to reach temperature equilibrium.
|The motor works at a constant load, but not long enough to reach temperature equilibrium. The rest periods are long enough for the motor to reach ambient temperature.
|Intermittent periodic duty
|Sequential, identical run and rest cycles with constant load. Temperature equilibrium is never reached. Starting current has little effect on temperature rise.
|Intermittent periodic duty with starting
|Sequential, identical start, run and rest cycles with constant load. Temperature equilibrium is not reached, but starting current affects temperature rise.
|Intermittent periodic duty with electric braking
|Sequential, identical cycles of starting, running at constant load and running with no load. No rest periods.
|Continuous operation with intermittent load
|Sequential, identical cycles of running with constant load and running with no load. No rest periods.
|Continuous operation with electric braking
|Sequential identical cycles of starting, running at constant load and electric braking. No rest periods.
|Continuous operation with periodic changes in load and speed
|Sequential, identical duty cycles run at constant load and given speed, then run at other constant loads and speeds. No rest periods.
Electrical units, amps and electrical wiring, wire gauge and AWG, electrical formulas and motors.
IEC and NEMA torque classifications of electrical motors.
NEMA enclosure classifications versus IEC enclosure classifications.
Inductive loads and power factors with electrical three-phase motors.