Insulation Class

The highest temperature in the motor’s hottest spot has a serious impact on the life of the electric motor. The temperature that occurs at that spot is a combination of motor design temperature and the ambient temperature. The insulation class shows the motor’s ability to withstand temperatures over time.

The motors have different insulation capabilities. The insulation codes show their thermal tolerance or ability to survive at a specified temperature for a period of time. The higher the designated code letter, the greater the heat capability.

It is based on the highest temperature the material can withstand continuously without degrading or reducing motor life. IES specify 5 different types of insulation classes:

• Class A – 105c
• Class E -120c
• Class B – 130c
• Class F – 155c
• Class H – 180c

In the example, we can see that the motor has an insulation class of F, indicating that the motor’s thermal tolerance is 155c.