Hey Guys,

One of our fans generally trips on a cold start. So i want to set up two start curves in the GE Multilin controller, a cold start and warm start. Its a 1500hp 4.16kV motor. This motor lives outside and our ambient air temp varies so much (Canada) that using stator winding RTDs or Bearing RTDs isn't really feasible (they are just basically high temp sensors). This motor is required for our process so we start it, it trips and then we short the emergency start contacts and start it again and it runs (time between starts is set so low 1min). These two consecutive starts of course is very hard on the stator windings (and this is were I want to use the warm start).

Everything above is just informational - my real question is:

Is there a general rule of thumb for stator winding cool down time for the cold start value. I'm looking at a cold start curve that is about 8 times FLA.