What is duty cycle of electrical motor?


#1

Duty Cycle

In NEMA world,typically duty cycle is referred to in one of two terms:

Continuous or intermittent

For IEC

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

S2-Short-time duty
The motor works at constant load,but not long enough to reach temperature equilibrium,and 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 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 electric breaking.
Sequential identical cycles of starting,running at constant load.Temperature equilibrium is not reached.


#2

S6-Continuous operation with intermittent load
Sequential,identical cycles of running with constant load and running with no load.No rest period

S7-Continuous operation with electric breaking
Sequential,identical cycles of starting,running at constant load,and electric breaking.No rest period.

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