Nominal motor current
A motor is usually constructed according to an insulation class. Also, the motor is rated a ‘nominal current’.
When the motor has a temperature equal to the ambient temperature and starts to run, it will be heated up
proportional with the current flowing through the motor.
By definition, when the current flowing through the motor is equal to the nominal rated current, the motor
temperature will rise to a temperature which is equal to the maximum allowable operation temperature for
that insulation class.
Example
• Insulation class of the motor: F
• Nominal current of the motor: 100 A
• Ambient temperature: 40 °C
When the motor is running continuously for an infinite time, the motor temperature will rise to a temperature
of 155 °C and will stabilize there. See also the graph below.
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