What is the recommended Insulation Class and Temperature for Induction Motor ?

(1 Min Read)

• Class F insulation with Class B temperature rise is the most commonly required insulation system for industrial motors i.e., max. temperature rise of 80 °C above ambient temperature.
• The use of Class F insulation (ambient temperature 40 °C + Max. permissible temperature rise 105 °C + Hotspot temperature margin 10 °C ) with Class B (ambient temperature 40 °C + Max. permissible temperature rise 80 °C + Hotspot temperature margin 10 °C ) temperature rise gives motors a 25 °C safety margin. This can be used to increase the loading of the motor for limited periods, to operate at higher ambient temperatures or altitudes or with greater voltage and frequency tolerances. It will help to extend insulation life.
• Hence a Class F Motor's insulation can go up to to a max temperature of 40+80+10 = 130°C is the recommended limit by most of the manufacturers.