Motor insulation temperature rise calculator
Check whether a motor’s winding stays within its insulation class: enter ambient temperature and measured temperature rise, pick the insulation class, and read whether the total stays under the class limit.
Winding temperature vs insulation class
Hot-spot temperature = ambient + measured rise. The class limit is the maximum permitted total winding temperature (IEC 60034): A 105 °C, E 120 °C, B 130 °C, F 155 °C, H 180 °C.
Service-factor allowance: leave roughly a 10 °C margin below the class limit for a 1.15 service factor, and remember the measured rise is a winding average while the true hot-spot can run a few degrees higher.
Keeping a motor inside its insulation class keeps it safe at full load.AO Ctrl stocks the motors and thermal-protection parts to help:
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Frequently asked questions
What is the maximum temperature for motor insulation classes A, B, F and H?
The calculator uses the IEC 60034 class limits: A 105 °C, E 120 °C, B 130 °C, F 155 °C and H 180 °C. The hot-spot temperature — ambient plus measured rise — is compared against the selected class maximum, and the tool shows the margin and a PASS or WARNING verdict.
How do I check if a motor winding is within its insulation class?
Add the ambient temperature to the measured temperature rise to get the hot-spot temperature, then compare it with the class limit. The calculator does exactly that — with the defaults of 40 °C ambient, an 80 °C rise and class F, the hot-spot is 120 °C, leaving a 35 °C margin.
How much margin should I leave below the insulation class limit?
Leave roughly a 10 °C margin below the class limit for a 1.15 service factor, and remember the measured rise is a winding average while the true hot-spot can run a few degrees higher. Keeping inside the class limit keeps the motor safe at full load.
AO Ctrl provides this tool for reference only.