Duty cycle of AC motors

Hello guys,

I need help understanding duty cycles of AC motors. I have read the following article explaining the difference between different types.

I'm not sure if I understood the S2 type. For example S2-30 min. These 30 minutes only refers to short time duty.
I wonder how to know rest time i.e. after what time the motor can be started again.

For example I have found the following data in one brochure:
Actuators are for open-close duty and positioning duty are rated for class A and B or types of duty S2 - 15 min. A special version for longer running is available for the S2 - 30 min duty.


Thank you.

For S2, the rest period must be long enough for the motor to reach ambient (room) temperature.
And how long is that then, you ask? Well, that depends on your motor and cooling. There's no easy answer unfortunately.

Try this. Might help you understand insulation class as it relates to duty cycle

http://ekeindia.com/learning-tutorials/electrical-motor-insulation-class/


And this

https://www.engineeringtoolbox.com/iec-duty-cucles-d_739.html

Exactly as CommissioningMan said, I have attached an explanation from IEC 60034-1.

Thank you all for your replies.
I'm not sure how to interpret this time data. For example S2-30 min!?!
What this 30 minutes means?
Does it means that motor needs 30 min to reach temperature equilibrium or something else?

It means it can run for 30 minutes before requiring to be off long enough to reach ambient temperature.

To me, these ratings are garbage. Without specifying what the cool-down time is or a percent duty cycle, you still can not specify a motor for a given application.

IMO, the rating should be 25%-60min or some-such, meaning it can run 25% of the time with a 60 minute maximum total cycle (run+rest). But what do I know?