The stator of the three-phase asynchronous motor and the synchronous machine, and the rotor of the three-phase wound motor have three-phase symmetrical windings. In the National Motor Standards, methods for measuring the DC resistance of these windings are specified. When measuring, the temperature of the winding to be tested must be measured. If the motor is in the actual cold state, the temperature can be corrected by the ambient temperature. When performing a type test or other test requiring accurate results, measure each phase resistance or each line resistance 3 times, and then take the average of 3 times as the measurement result.
● Direct measurement of phase resistance
When the stator or rotor three-phase winding phase of the motor has 6 terminals at the head and tail, or the three-phase winding is connected to the star (Y-shaped) inthe motor, but the neutral line is taken out except the three phase lines ( When the star point is also taken out, the DC resistance of each phase can be measured separately.
● Measuring line resistance
When the three-phase winding of the stator of the motor is connected to the star (Y) or the triangle (△) inside the motor, only the resistance of each of the two external ends (ie, the line resistance) can be measured, and then the corresponding phase resistance is converted by the formula.
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