Test method for temperature rise of induction motors
There is no unified conclusion about the temperature rise problem of overlapping frequency methods; in fact, there is a method associated with the motor and the test. See Annex: superposition temperature rise factor analysis. DIV> question evaluation, thank you!
The temperature rise test of the direct load method shall be carried out at rated frequency, rated voltage, rated power or nameplate current for continuous rating (S1 working system) motors. When testing, the three-phase asynchronous motor should keep the rated load until the temperature rise of each part of the motor reaches the thermal stable state. During the test, the voltage, current and input power of the motor, as well as the cooling medium of the stator core, the bearing, the inlet and outlet of the air duct, and the temperature of the surrounding cooling medium are recorded every half hour. If the method of live temperature measurement is adopted, the resistance of the winding shall be measured every half hour as well as before the test. During the test, measures should be taken to minimize changes in coolant temperature. In order to shorten the test time, the temperature rise test can be carried out at the beginning of proper overload. Short term rating (S2 work) motor, when testing, according to the length of the work time, every 5-15min records a test data. Intermittent cycle work quota (S3 work) motor, such as without other provisions, test, each cycle should be 10min, until all parts of the motor temperature rise to thermal stability. The temperature shall be tested at the end of the last half of the load period. In order to shorten the test time, the load can last for a period of time at the beginning of the test.
The equivalent load method includes the stator frequency superposition method to reduce the voltage load method. The equivalent load method is limited to the motors employed by the S1 system. For equipment limited to 100KW, the lower voltage load method shall be adopted. For the vertical or above 300KW, if the stator frequency superposition method is allowed, the following temperature rise test shall be carried out when the voltage load reduction method is adopted.A: carries out no-load temperature rise test at rated frequency rated voltage and determines the temperature rise and core temperature rise at this time.B: conducts temperature rise test at rated frequency, 1/2 rated voltage and full load current, and determines the temperature rise of the winding, the temperature rise of the core and the full load current
