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Motor bearings, also known as electric motor bearings or motor drive bearings, come in four common types: rolling bearings, sliding bearings, journal bearings, and oil-impregnated bearings. What are the temperature standards for motor bearings while they are in operation? Below, we reveal the temperature standards for motor bearings. In practice, the casing temperature is usually considered acceptable as long as it’s not hot to the touch. The stray losses on the surface of the squirrel-cage rotor are high, resulting in high temperatures; generally, this is kept within limits that do not pose a risk to the adjacent insulation. It can be estimated by applying irreversible color-changing paint in advance. Generally speaking, if the motor’s insulation class is A and the ambient temperature is 40°C, then the temperature of the motor’s enclosure should be less than 60°C. The core temperature rise due to winding contact (using the thermometer method) shall not exceed the temperature rise limit of the insulation of the winding in contact with it (using the resistance method); namely, 60°C for Class A, 75°C for Class E, 80°C for Class B, 100°C for Class F, and 125°C for Class H. The temperature of rolling bearings should not exceed 95°C, while the temperature of sliding bearings should not exceed 80°C. High temperatures can cause changes in the oil quality and damage the oil film. General motor operating procedures stipulate that the maximum temperature for rolling bearings should not exceed 95 degrees Celsius, while the maximum temperature for sliding bearings should not exceed 80 degrees Celsius. It is also required that the temperature rise does not exceed 55 degrees Celsius (the temperature rise is the bearing temperature minus the ambient temperature during testing); according to GB3215-82 4.4.1, during the operation of the pump, the maximum temperature of the bearings shall not exceed 80 degrees. JB/T5294-91 3.2.9.2 The temperature rise of the bearing shall not exceed 40 degrees above the ambient temperature, and the maximum temperature shall not exceed 80 degrees. JB/T6439-92 4.3.3 When the pump is operating under specified conditions, the surface temperature of the built-in bearings shall not be 20 degrees higher than the temperature of the medium being transported, with the maximum temperature not exceeding 80 degrees. The surface temperature rise at the external surface of the surface-mounted bearing should not exceed 40 degrees above the ambient temperature. The maximum temperature should not exceed 80 degrees. JB/T7255-94 5.15.3 Operating temperature of bearings. The bearing temperature rise shall not exceed 35 degrees above the ambient temperature, and the maximum temperature shall not exceed 75 degrees. JB/T7743-95 7.16.4 The temperature rise of the bearing shall not exceed 40 degrees above the ambient temperature, and the maximum temperature shall not exceed 80 degrees. JB/T8644-1997 4.14 The temperature rise of the bearing shall not exceed 35 degrees above the ambient temperature, and the maximum temperature shall not exceed 80 degrees.