How to measure the resistance between the coils of a three-phase motor in the resistance block of a multimeter
The phase-to-phase resistance of a motor cannot be measured with a swing meter because the voltage of the swing meter is too high and may break through the insulation of the coils. Normally, we use a multimeter resistance block to measure the resistance between the coils of a three-phase motor. Whether it is a star connection or an angle connection, the resistance between the three phase windings should be very small and normal between the windings.
But to make it clear that the three-phase windings are actually each one, in addition to the smaller power motors will be connected internally into a star or triangle, high-power motors need to be connected to the connection piece to be connected, or the use of star-delta step-down control wiring, if the connection piece is removed, the resistance between the three-phase windings should be greater than one megohm.
Three-phase winding insulation to ground, you can use megohmmeter to measure, usually infinity, at least greater than 0.5 megohm, the larger the motor insulation resistance requirements of the higher, 45 kilowatts of motor, insulation resistance should be in more than one megohm.
The insulation to ground here is the junction of the windings to the motor body, not the insulation to the earth wire or earth. So when we measure, we only need to measure the resistance of the winding and the body.
