Rotating shaftMeasuring method for internal temperature of motor shell

First, the thermometer method:

Rotating shaftThis method uses the thermometer to determine the temperature directly, the most convenient. But the thermometer can only touch the surface of the motor parts., only the surface temperature is measured. The maximum temperature inside the motor can not be measured with a thermometer.

Second, Resistance method:

This method can only be used to determine the average temperature of the winding, the principle is as follows.

Rotating shaftBefore the motor runs, we first measure the cold resistance of the windings.R1,. That is, when the winding temperature is equal to the cooling medium temperature T1 resistance. Set the motor after the winding humidity rise to T2, the winding resistance will increase to R2. The temperature is measured in Celsius, and the copper windings have the following relationships: r1/r2= (235+T1)/(235+T2). From the upper-class, such as R1, R2 and T1 are known, you can solve the T2. T1-t2 is the temperature rise of the winding to the cooling medium. For the aluminum wire winding, change the constant 235 in the formula to 225.

Third, superposition method(Double-bridge Live Temperature measurement method):

Without interrupting the alternating load current, a weak DC current is superimposed on the load current to measure the variation of the DC resistance of the winding with the temperature to determine the temperature rise of the AC winding. The temperature rise limit of each part of the motor is related to the grade of the absolute rubber material, which is related to the temperature of the cooling medium, and also to the method of measuring temperature. The life of an insulating material is determined by its absolute temperature on a long journey, and not by the temperature rise. From winter to summer, from the north to the south, the environmental temperature changes very much. When the ambient temperature is low, the temperature rise limit of the motor can be improved, and when the ambient temperature is high, the temperature rise limit of the motor must be reduced. For the sake of clarity, the standard temperature of the cooling medium must be specified at the same time when the temperature rise limits of the motor parts are specified. The standard temperature of the cooling medium stipulated in China's electrician technical standard is4q℃. According to this regulation, the temperature rise of various parts of the motor, the application of different insulating materials and different temperature measurement methods, there are different temperature rise limit.

Four, buried quantity check temperature meter method:

Rotating shaftThe larger motor, in the assembly, is often estimated to have a higher temperature of the points, buried temperature meter. Temperature components have thermocouple and resistance thermometer. The heated end of the thermometer can be buried deep in the groove, such as between the conductor and the bottom and the upper and lower conductor. The extraction end of the thermometer is drawn to the outside and is connected to the measuring instrument to read out the temperature. The more the application of the thermometer, the more the measured temperature is likely to be close to the hottest temperature.