Question: what is the difference between class b and class f insulation?
Answer: Temp. ... For example, an 80°C rise is often referred to as a 'Class B', as 80°C is the maximum allowable temperature rise for a 1.0 S.F. motor with Class B insulation and a 40°C ambient temperature. This practice means that a motor with Class F insulation and an 80°C rise is referred to as an 'F/B' motor.