Insulation class of motor

The insulation grade of the motor refers to the heat resistance grade of the insulating material used, divided into Y, A, E, B, F, H and C. The allowable temperature rise refers to the limit of the increase in the temperature of the motor compared with the ambient temperature.

        Insulation temperature class               Y       A      E       B       F       H       C

　　Maximum allowable temperature (℃) 90   105   120   130   155   180   180 or more

　　 Winding temperature rise limit (K)     60     75     80    100   125

　　 Performance reference temperature (℃) 80    95    100    120    145

        In electrical equipment such as motors, insulating materials are the weakest link. Insulating materials are particularly susceptible to accelerated aging and damage due to high temperatures. Different insulating materials have different heat resistance, and electrical equipment using different insulating materials has different ability to withstand high temperatures. Therefore, general electrical equipment stipulates the maximum operating temperature.