My AC induction motor has to run in indexing table application which works 24X7. Each cycle has 1.2sec (0.2sec idle). Hence per hour the motor has 3000 cycles. Iam having forced cooling fans on motor to dissipate the heat generated due to high start/stop. My motor brake (AC) releases within 0.04sec engaging within 0.007sec. hence the total braking action is about only 0.47sec. Pls tel me the 0.2 sec is enough for idle condition of motor.
Well as you know, S3 is intermittent duty, but I think S3 maybe something like 20 min run per hour. See the site below which states equal on/off periods I think. Better off replacing with S1 motor I would think, unless above 20 kW. or so.
In order to answer this you need to know 1. The motor torque and current vs time. 2. The power lost in the motor. 3. The motor temperature rise per watt of power loss with and without the fan.
