1. During the pump operation, the maximum temperature of the bearing does not exceed 80.
2. The temperature rise of the bearing shall not exceed the ambient temperature of 40, and the maximum temperature shall not exceed 80.
3. When the pump is running under the specified working conditions, the temperature of the outer surface of the built-in bearing should not be higher than the temperature of the conveying medium by 20, and the maximum temperature is not higher than 80. The temperature rise of the outer surface of the external bearing should not be higher than the ambient temperature of 40. The maximum temperature is not higher than 80.
4. The operating temperature of the bearing. The bearing temperature rise must not exceed the ambient temperature of 35 and the maximum temperature must not exceed 75.
5, the bearing temperature rise must not exceed the ambient temperature of 40, the maximum temperature must not exceed 80.
6, the bearing temperature rise must not exceed the ambient temperature of 35, the maximum temperature must not exceed 80.
The rules are the same, but the various manufacturing plants may be slightly different due to different manufacturing processes, but not too big.
Usually we measure the degree of motor heating by using "temperature rise" instead of "temperature". When "temperature rise" suddenly increases or exceeds the maximum operating temperature, the motor has failed. Below, Dalan Motor Xiaobian discusses some basic concepts and discusses with everyone.
1. Insulation grade of insulating material:
The insulating materials are divided into seven grades of Y, A, E, B, F, H, and C according to their heat resistance, and their limit working temperatures are 90, 105, 120, 130, 155, 180 ° C, and 180 ° C or higher, respectively. The ultimate operating temperature of the insulating material refers to the temperature at which the oil pump motor is the hottest in the winding insulation during the expected life of the design. According to experience, Class A materials have a life expectancy of 10 years at 105 ° C and Class B materials at 130 ° C. However, under actual conditions, the ambient temperature and temperature rise will not reach the design value for a long time, so the general life is 15-20. year. If the operating temperature exceeds the limit operating temperature of the material for a long time, the aging of the insulation is intensified and the life is greatly shortened. Therefore, when the motor is running, temperature is one of the main factors of life.
2, temperature rise
Temperature rise is the temperature difference between the motor and the environment caused by the heating of the motor. The running motor core is in the alternating magnetic field, which will cause iron loss. When the winding is energized, copper loss will occur, and Other stray losses will occur. These will increase the temperature of the motor. On the other hand, the motor will dissipate heat When the heat and heat are equal, the equilibrium state is reached, and the temperature does not rise and stabilizes at a level. When the heat is increased or the heat is reduced, the balance is broken, the temperature continues to rise, the temperature difference is increased, the heat is increased, and a new balance is reached at another higher temperature. However, the temperature difference at this time, that is, the temperature rise has increased more than before, so that temperature rise is an important indicator in the design and operation of the motor, which indicates the degree of heat generation of the motor. In operation, if the temperature rise of the motor suddenly increases, Indicates that the motor is faulty, or the air duct is blocked or the load is too heavy.
3. Relationship between temperature rise and temperature: For a motor that operates normally, its temperature rise should be independent of the ambient temperature under the rated load, but it is actually affected by factors such as ambient temperature.
(1) When the temperature drops, the temperature rise of the normal motor will decrease slightly. This is because the winding resistance r is lowered and the copper loss is reduced. For every 1 °C drop in temperature, r decreases by about 0.4%.
(2) For self-cooling motors, the temperature rise is increased by 1.5 to 3 °C for every 10 °C increase in ambient temperature. This is because the copper loss of the winding increases as the temperature rises. Therefore, temperature changes have a greater impact on large motors and closed motors.
(3) The air humidity is 10% higher. Due to the improvement of heat conduction, the temperature rise can be reduced by 0.07~0.38°C, with an average of 0.19°C.
(4) The altitude is 1 000 m, 100 m per liter, and the temperature rise increases by 1% of the temperature rise limit.
4, the limit operating temperature and the maximum allowable working temperature
It is generally said that the ultimate operating temperature of class a is 105 ° C, and the maximum allowable operating temperature of class a is 90 ° C. So, what is the difference between the extreme operating temperature and the maximum allowable operating temperature? In fact, this is related to the measurement method. Different measurement methods reflect different values ​​and have different meanings.
(1) The measurement method of the thermometer method reflects the local surface temperature of the winding insulation. This number is on average about 15 °C lower than the actual maximum temperature of the winding insulation, the "hottest spot". This method is the simplest and most widely used in medium and small motors.
(2) The resistance method reflects the average value of the copper temperature of the entire winding. This number is reduced by 5 to 15 ° C depending on the actual maximum temperature. The method measures the cold state and the thermal resistance of the conductor, and calculates the average temperature rise according to the relevant formula.
(3) When embedding the thermometer test, a copper or platinum resistance thermometer or thermocouple is embedded in the winding, the core or other components that need to be measured at the highest temperature. The measurement results reflect the temperature at which the temperature measuring element contacts. Large motors often use this method to monitor the operating temperature of the motor. The temperature measured by various measuring methods has a certain difference from the actual maximum temperature. Therefore, it is necessary to subtract the difference from the "limit operating temperature" of the insulating material to be the "highest allowable operating temperature".
5, the temperature limit of each part of the motor
(1) The temperature rise of the core in contact with the winding (thermometer method) shall not exceed the temperature rise limit of the winding insulation (resistance method), that is, Class A is 60 °C, Class E is 75 °C, Class B is 80 °C, Class F is 100 ° C and Class H is 125 ° C.
(2) The temperature of the rolling bearing should not exceed 95 °C, and the temperature of the sliding bearing should not exceed 80 °C. If the temperature is too high, the oil quality will change and the oil film will be destroyed.
(3) In practice, the temperature of the casing is often judged by hot and not hot, but it is related to the touch of each person, and the error is large, and it is necessary to accumulate certain experience.
----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant
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