Type of dutyen (VDE 0530)

Continuous-running duty S 1

Operation at constant load, the duration 
of which is sufficient to reach thermal equilibrium. 

Key to curves

Short-time duty S 2

Operation at constant load, duration of which, however, is not sufficient to reach thermal equilibrium, with a subsequent rest lasting until the motor temperature differs no more than 2 K from the temperature of the coolant.

Example: S 2 – 60 min
(The time means 60 minutes rating)

Intermittent-periodic duty S 3

Operation composed of a sequence of identical cycles of which each cycle includes a period at constant load and a rest whereby the starting current does not have any considerable effect on heating.

Example: S 3 – 10 %
(The percent figure refers to the cyclic duration factor)