Thermal analysis of asynchronous machines under intermittent loading
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Kuupäev
2019
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Ajakirja pealkiri
Ajakirja ISSN
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Abstrakt
The operation of electric machines is accompanied by losses which are mostly
converted to heat. The heat needs to be dissipated from the machine. With a properly dimensioned
motor, the arising heat is balanced with dissipated one. After the motor is started at ambient
temperature, all functional parts of the machine are gradually warmed until stabilized. Any
overloading of the machine leads to stabilization at temperatures higher than expected by the
designers. High temperatures in the machine could cause a crash by damaging an insulation. In
case of machines with permanent magnets, the temperature affects their magnetic properties and
can leads to demagnetization at the Curie temperature. Therefore, the measuring of temperature
is so important for verifying the allowed warming of the motor. Contact and noncontact methods
could be used for temperature measuring. Thermal warming and temperature distribution in an
electric machine can be also determined by theoretical calculations based, for example, on the
finite element method. This method is used by a number of computer software such as Ansys.
The article deals with generation and propagation of heat in electric motors and with measuring
of warming characteristics with a variable value of a load factor for intermittent periodic loading
of asynchronous machine. The loading is carried out by the dynamometer. The temperature
measurement is implemented by temperature sensors which are located on the stator winding of
the asynchronous motor and are in operation for the whole time the motor is loaded.
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Märksõnad
electric machine, loading, losses, load factor, warming, articles