Three phase asynchronous motor stator winding of the first and last end of the discrimination method, respectively, using the multimeter inspection method, low voltage AC power supply method, fast judgment of the three-phase asynchronous motor stator winding end, need a friend reference.

As follows:

1、 One of the inspection methods with Multimeter

① Judge the two outgoing terminals of each phase winding. Distinguish the two wire ends of each phase of the three-phase winding with the resistance of the multimeter, and make hypothesis number. Connect the wires according to the method in Fig. 1-1.

② Judge the beginning and the end. Look at the direction of the pointer swing of the multimeter (microampere gear). At the moment of closing the switch, if the pointer swings to the side greater than 0, the head or tail of the wire connected to the battery positive electrode and the negative pole of the multimeter are the same. If the pointer swings in the opposite direction, the lead connected to the positive electrode of the battery and the positive pole of the multimeter are the same as the first or the last end.

③ Then connect the battery and the switch to the other two wire ends, and then test, the head and tail ends of each phase can be correctly identified. Figure 1 one of the methods for checking multimeter

2、 Check method 2 with Multimeter

① Judge the two outgoing terminals of each phase winding. Distinguish the two wire ends of each phase of the three-phase winding with the resistance of the multimeter.

② Each phase winding is assumed to be numbered U1, U2, V1, V2 and W1, W2.

③ Connect according to Figure 1-2 to judge the end. Turn the motor rotor by hand. If the pointer of the multimeter (microampere) does not move, it is proved that the assumed number is correct. If the pointer is deflected, it means that there is a wrong number at the beginning and end of one phase, and the measurement should be repeated one by one until it is correct.

Fig. 2 multimeter check

3、 Low voltage AC power supply method

① Judge the two outgoing terminals of each phase winding. Distinguish the two wire ends of each phase of the three-phase winding with the resistance of the multimeter, and make hypothesis number.

② Connect according to figure 1-3. Connect any two windings in series, then connect them to the AC voltage range of voltmeter or multimeter, and connect the third phase winding with 36V low voltage AC power supply.

③ Judge the beginning and the end. After power on, if the voltmeter does not read, it means that the two wire ends connected together are the same as the head end or the tail end. The voltmeter has readings. One of the two wire ends connected together is the head end and the other is the tail end. Any fixed end is the known head end. The head and tail ends of the third phase can be determined by the same method.

Fig. 3 low voltage AC power supply method

3. The wiring shall be conducted according to the three-phase asynchronous motor nameplate, and the grounding protection line shall be added. 4、 Training precautions 1. When measuring the insulation resistance of three-phase asynchronous motor, it is absolutely not allowed to measure the insulation resistance with a megohmmeter when the equipment is charged; after the measurement, the equipment should be discharged, otherwise it is easy to cause electric shock accident. 2. It is forbidden to touch the measuring part of the equipment or the terminal of the megger by hand before the megger stops rotating. Do not touch the exposed part of the lead wire when removing the wire.

After distinguishing the head and tail, connect the wires according to the figure below.