What is the classification of duty of rotating electrical machines?

What is the classification of duty of rotating electrical machines?  
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1 Answer

Answer :

S1 – Continuous operation at rated load (MCR) in 40 °C

S2 – Short time operation (STR) for 5 minute or 15 minutes or 30 minutes.

S3 – Intermittent periodic operation (resting and loading e.g. cranes, lifts etc)

S4 – As for S3 but with starting

S5 – As for S3 with electric braking

S6 – Continuous cyclic operation. 
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