What is the maximum temperature the motor of centrifugal pump can withstand?
The insulation grade of the motor of centrifugal pump refers to the heat resistance grade of the insulating material used, which is divided into A, E, B, F, and H grades. The allowable temperature rise refers to the limit that the temperature of the motor is increased compared with the ambient temperature.
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Temperature rise refers to the value that the temperature of the stator winding of centrifugal pump is higher than the ambient temperature under the rated operating state of the motor (the ambient temperature is specified as 35°C or below 40°C, if the specific value is not marked on the nameplate, it is 40°C)
Insulation temperature class A class E class B class F class H class
Maximum allowable temperature (℃) 105 120 130 155 180
Winding temperature rise limit (K) 60 75 80 100 125
Performance reference temperature (℃) 80 95 100 120 145
In electrical equipment such as generators, the insulating material is the weakest link. The insulating material is especially susceptible to high temperature and accelerated aging and damage. Different insulating materials have different heat resistance properties, and electrical equipment using different insulating materials can withstand The ability of high temperature of centrifugal pump is different. Therefore, general electrical equipment stipulates the maximum temperature for its work.
According to the ability of different insulating materials to withstand high temperature, 7 maximum allowable temperatures are specified for them, which are arranged in accordance with the temperature: Y, A, E, B, F, H and C. Their allowable operating temperatures are: 90, 105, 120, 130, 155, 180 and 180°C or higher. Therefore, Class B insulation indicates that the generator adopts an insulation heat-resistant temperature of 130°C. The user should ensure that the generator is not used when the generator is working. The insulation material exceeds this temperature to ensure the normal operation of the generator.
Insulation material with insulation class B, mainly made of mica, asbestos, glass fiber glued or impregnated with organic glue
●At what temperature can the motor work normally? What is the maximum temperature the motor can withstand?
Answer: If the temperature of the measured motor cover exceeds the ambient temperature by more than 25 degrees, it indicates that the temperature rise of the motor has exceeded the normal range. Generally, the temperature rise of the motor should be below 20 degrees. Generally, the motor coil is made of enameled wire, and when the temperature of the enameled wire is higher than about 150 degrees, the paint film will fall off due to the high temperature, resulting in a short circuit of the coil. When the coil temperature is above 150 degrees, the temperature of the motor casing is about 100 degrees, so if it is based on its casing temperature, the maximum temperature the motor can withstand is 100 degrees.
●The temperature of the motor should be below 20 degrees Celsius, that is, the temperature of the motor end cover should be less than 20 degrees Celsius when it exceeds the ambient temperature, but what is the reason why the motor heats up more than 20 degrees Celsius?
Answer: The direct cause of motor heating is due to the large current. Generally, it may be caused by the short circuit or open circuit of the coil, the demagnetization of the magnetic steel or the low efficiency of the motor. The normal situation is that the motor runs with high current for a long time.
●What causes the motor to heat up? What kind of process is this?
Answer: When the motor is running under load, there is power loss in the motor, which will eventually become heat energy, which will increase the temperature of the motor and exceed the ambient temperature. The value by which the motor temperature is higher than the ambient temperature is called the ramp-up. Once the temperature rises, the motor will dissipate heat to the surroundings; the higher the temperature, the faster the heat dissipation. When the heat emitted by the motor per unit time is equal to the heat dissipated, the temperature of the motor will no longer increase, but maintain a stable and constant temperature, that is, in a state of balance between heat generation and heat dissipation.
●What is the allowable temperature rise of the general motor? Which part of the motor is most affected by the temperature rise of the motor? How is it defined?
Answer: When the motor is running under load, it is necessary to play its role as much as possible, that is, the larger the output power, the better the load (if the mechanical strength is not considered). But the greater the output power, the greater the loss of power, the higher the temperature. We know that the weakest thing in the motor is the insulating material, such as enameled wire. There is a limit to the temperature resistance of insulating materials. Within this limit, the physical, chemical, mechanical, electrical and other properties of insulating materials are very stable, and their working life is generally about 20 years. Exceeding this limit, the life of the insulating material is shortened sharply, and even burns out. This temperature limit is called the allowable temperature of the insulating material. The allowable temperature of the insulating material is the allowable temperature of the motor; the life of the insulati
