New Member Question on cold & hot starts

[Dennis Alwon]

I got this as a pm from Camilo

hi,

just want to know what is meant by 3 cold and 2 hot starts for 11kV motors.

the sequence in the design specs stated like this: "three cold starts with respect to two hot starts shall be possible in sequence. It shall be interrupted between second cold start and the first hot start by a cooling period of maximum 30 minutes in case of motors for heavy start up conditions."

thanks in advance.

camilo

 

[Hv&Lv]

It has to do with the thermal protection of the motor. You get a motor too hot during starting sequences insulation could melt, or the conductors in the motor could short. It is a common requirement for high voltage motors.
Here is a paper on thermal protection and design:
http://www.gedigitalenergy.com/multilin/family/motors/motor_thermal_model.pdf

 

[camilopinoy]

thanks Hv&Lv. the article helps a lot.:thumbsup: