chapter  12
23 Pages


Practice has shown that increasing the winding temperature over the insulation class limit reduces the insulation life L versus its value L0 at the insulation class temperature (Figure 12.1):

It is thus very important to set the maximum winding temperature as a design constraint. The highest temperature spot is located in the stator end connections. The rotor cage bars experience a larger temperature, but they are not, in general, insulated from the rotor core. If they are, the maximum (insulation class dependent) rotor cage temperature has to be also observed. The thermal modeling depends essentially on the cooling approach.