Several operating methods for judging the first and last ends of motor windings with a pointer multimeter

When the labels of the six output terminals of the three-phase asynchronous are missing or unclear, or after the winding is re-wound, it is necessary to find out which two terminals belong to the same phase, which one is the beginning of the coil, and which one is the end of the coil. The following introduces several operating methods for using pointers to determine the beginning and end of motor windings.

method one

Use a multimeter to identify the two wire ends of each phase of the three-phase winding and perform hypothesis numbering.

Observe the direction in which the pointer of the multimeter (microampere setting) swings. When the switch is turned on, if the pointer swings to the side greater than 0, then the lead connected to the positive terminal of the battery and the lead connected to the negative terminal of the multimeter are the same beginning or end. If the pointer swings in the opposite direction, the lead connected to the positive terminal of the battery and the lead connected to the positive terminal of the multimeter are at the same beginning or end.

Then connect the battery and switch to the two wire ends of another phase and conduct a test to correctly identify the beginning and end of each phase.

Method Two

First, use the resistance range of a multimeter to distinguish the two wire ends of each phase of the three-phase winding. Assume that the windings of each phase are numbered u1, u2, v1, v2 and w1, w2. Follow the diagram below to connect the wires and determine the beginning and end. Turn the motor rotor by hand. If the pointer of the multimeter (microampere range) does not move, it proves that the assumed number is correct. If the pointer deflects, it means that the assumed number of the first and last ends of one of the phases is wrong. It should be adjusted phase by phase and retested until it is correct. until.

Method three

First, use a multimeter to electrically isolate the two wire ends of each phase of the three-phase winding, perform hypothesis numbering, and connect the wires as shown below. Connect any two phase windings in series and then connect it to the AC voltage block of the multimeter, and connect the third phase winding to 36v low voltage AC.

After powering on, if the voltmeter has no reading, it means that the two wires connected together are the beginning or the end. The voltmeter has a reading. One of the two wires connected together is the head end and the other is the tail end. If any end is determined as the known first end, the same method can be used to determine the first and last ends of the third phase.