Induction Motors Duty Cycles

Type of Duty

The following shall be the duty types:

Sl -Continuous duty
The motor works at a constant load for enough time to reach temperature equilibrium.

S2 -Short time duty
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

S3 -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

S4 -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.

S5 -Intermittent periodic duty with starting and electric braking
Sequential, identical cycles of starting, running at constant load and running with no load. No rest periods.

S6 -Continuous duty with intermittent periodic loading
Sequential, identical cycles of running with constant load and running with no load. No rest periods.

S7- Continuous duty with starting and electric braking
Sequential identical cycles of starting, running at constant load and electric braking. No rest periods

S8 -Continuous duly with periodic speed changes
Sequential, identical duty cycles run at constant load and given speed, then run at other constant loads and speeds. No rest periods.