How to judge a three-phase ac motor
Three-phase resistance line resistance is measured with meter, first to see if there is resistance, and then to the equilibrium value is decrease (maximum minimum), general corporate control within 1% resistance unbalance degree, resistance unbalance affects a relatively high fever, insulation damage easily.
A visual inspection, Measure U1U2, V1V2, W1W2 resistance, the three-phase resistances should be equal, and the three phase maximum difference should not exceed 2% of the mean 3, if it's a multimeter, it's almost the same Monitor current and motor temperature after idle running
You measure U1, U2, w1, V1, V2 with ohm, which is the best thing you can do if you don't have a bad one, you can measure the resistance to the ground
How to measure the good and bad of the motor using the multimeter ohm. One, check to see if the road is open, U1 pairs U2 V1 to V2 W1 pair, check insulation U1 to V1, W1 U1, V1 W1 pair.
First, the power supply is cut off, and the hand disk motor turns, whether the bearing card dies, the rotor sweep, etc. Mechanical fault. Disconnect the motor power cord (U1, V1, W1, U2, V2, W2), measured with a multimeter, U1, U2, V1, V2, W1 and W2 resistance size, three-phase resistance is similar to normal, if the difference is too big there is winding interturn short circuit, also check the resistance between three-phase (three-phase resistance between infinite is normal) and the resistance (to casing).
