MOTOR DUTY S1 VS S3 1

[J Dua]

I HAVE INTERMITTENT LOAD OF PARTICULAR PLANT AREA, EARLIER FOR THIS INTERMITTENT LOAD WE WERE USING S1 CONTINUOUS RATING MOTOR 7.5 KW ,THE FAILURE RATE WAS MORE FOR BOTH WINDING AND BEARING , THE WORKING AMBIENT IS MORE AS OF HOT BILLETS ROLLER AREA.

WHAT IS RECOMMENDED THE DUTY OF THE MOTOR, SHOULD I GO FOR S3 INTERMITTENT OR OTHER WWAY TO THINK IS BY OPT FOR S3 DUTY MOTOR, THE RATE WILL BE MORE,
AS PER MY UNDERSTANDING FOR INTERMITTENT LOAD, IF WE USING S1 CONT DUTY MOTOR IS BETTER OPTION.

PLEASE CLARIFY.

 

[7anoter4]

As I understand you have a hot billet roller driven by 7.5 kW motor.
At first, the billet has to be smaller cross section than maximum permitted [rated].
In my opinion a recording work of 24 hr. will state how the load is distributed as maximum [and average] and the load frequency.
IEC 60034-1 S6 it could be the suitable duty, in my opinion, since there is no time de-energized at rest.
The ambient temperature it is an important factor, also. You have to derate the motor power according to actual temperature with respect to maximum rated.