The key is what is the insulation level of your motor. If it is a Class A, the ambient temperature is 40 degrees C, then the temperature of the motor's shell should be less than 60.
Temperature limit of various parts of the motor
(1) the temperature rise of the core contact with the winding (thermometer method) should not exceed the temperature rise limit of the winding insulation (resistance method), that is, the class A is 60 degrees, the E level is 75 degrees, the B level is 80 degrees, the F level is 100 degrees, and the H level is 125 degrees.
(2) the rolling bearing temperature should not exceed 95 centigrade, and the temperature of the sliding bearing should not exceed 80 degrees C. As the temperature is too high, the oil can change and destroy the oil film.
(3) in the practice of the temperature of the shell, it is often not hot.
(4) the stray loss of the squirrel cage rotor is very high, and the temperature is high, which is generally limited to the adjacent insulation. An irreversible varnish can be estimated in advance to estimate