Electrical network motor in the process of using, may present terminal block wiring board is damaged, then lead to cannot distinguish six terminals and cohesion of the internal winding connection, this paper share the multimeter to ac and dc method the detailed operation on identifying the beginning and the end of the three-phase winding motor. 1, the discriminant of the winding two terminals of the motor with three-phase winding, each phase winding has two terminals, the discriminant of each phase winding terminal applicable multimeter ohm. Put the multimeter R× 10Ω, measuring any two terminals of the resistance in the motor terminal box, if resistance is very small, display the current measured two terminals of a phase winding terminal, then use the same method to find the other two phase winding terminal, because each phase winding structure identical, therefore has the meantime a set of terminal marked as U phase, the other two groups of terminals are marked as V and W phase separation. 2, identifying the winding tail end of the first motor can not distinguish the U, V, W phase, but in the end of each phase winding is necessary to distinguish. Discriminant first end of the commonly used way to have a dc winding method and communication method. 1) dc method of judging the first end of the three-phase winding in the difference between the end of a phase winding first by applying the method of dc, it is necessary to have ascertained the winding two terminals. Dc method first discriminant winding end puts multimeter minimum dc current file, red, black pens and separation by a group of two terminals of the winding, and then to the other one phase winding two terminals of the battery and switch, switch on, at the instant of the switch is closed, if the clock right swing, indicate the battery terminals and red pens and the anode receive receive terminal for side (with the sameBattery cathode by the terminal and terminal for side) with the same black pens and receive, if the clock swings to the left, indicate the battery negative terminal connect terminals and red pens and receive to end, with the same figure in whose hands the right swing, indicate the Wa end with Ua end to end, with the same again break switch, two pens and pick up one of the remaining two terminals of the phase winding, using the same method to judge the phase winding terminals. Identify each phase winding after the end of the same name, will be of the same nature three end with the same name as the winding head end, the rest of the three terminals for the winding end. Because of the motor winding resistance is small, switch closure time not too long, to avoid the battery run out or burn out. Dc method judging winding end with the same principle is: when closing switch moment, W winding electromotive force, arising from Russia but have a current through the electromotive force polarity for Wa, Wb negative, because the other two phase winding and within easy reach of W phase winding, W on the phase winding is induced electromotive force on the two phase winding, if Ua end with end to end with the same Wa, the Ua the polarity is positive, U phase winding into a circuit with a multimeter, U phase winding of induction electromotive force of the current flow from red pens and multimeter, the clock will swing, right open closed after one period of time, into the W phase winding current basically stable, W phase winding electromotive force was not occurred, the other two phase winding nor inductive electromotive force, multimeter the clock will stop at zero calibration. (2) communication method in the difference between the first end winding, by applying the method of communication is also asking has been ascertained and the winding two terminals. Communication method to judge winding fore and aft of the two phase winding first link up the two terminals, multimeter under ac voltage, red, black pens and separation after the two phase winding of the other two terminals, and then to the rest of the phase windings to light bulbs and 220 v ac power, if the clock is marked by voltage indicator, red, black pens and pick up the two terminal end (for different nameLink up the two terminals are same side)Changing winding again, do the above test, multimeter indicate voltage value is 0, indicating UbWa for side (with the sameUaWb for side) with the same。 Identify each phase winding after the end of the same name, will be of the same nature three end with the same name as the winding head end, the rest of the three terminals for the winding end. Communication method of judging the principle is: the same name as the 220 v ac voltage by the bulb step-down to a phase winding, the other two phase winding induction voltage, if the two phase winding is end with different end link up with the same name, the superposition of two voltage on the phase winding increases one times, multimeter can have voltage indicator, if the two windings is end with the same name with the same cohesion, superposition of two voltage on the phase winding will cancel each other out, multimeter measured voltage is 0.
