Method for Judging the Same Name End of Three Phase Asynchronous Motor Windings with a Multimeter
Method 1: Triangle connection measurement method
Step 1: Set the multimeter to R × Measure the six outgoing wires and two grounding wires of the motor junction box at 100 gears to determine the three-phase winding.
Specific methods; Connect the red (or black) probe to one of the lead wires; The black (or red) pen contacts the other five lead wires in sequence; The two outgoing terminals of the channel (referring to large deflection and low resistance) are in one phase and marked (it is recommended to use knotting or coloring as identification marks) to distinguish them from the following two phases. Similarly, the six outgoing lines are divided into three groups (as shown in Figure 2).
Step 2: Set the multimeter to the current microampere range, and check the wiring as shown in the figure to determine the beginning and end of the two-phase winding.
Specific methods:
(1) Set the multimeter to the current microampere range;
(2) Connect the red and black probes of the multimeter to the two endpoints of one winding of the motor;
(3) Then, contact the two endpoints of the other phase of the motor with the negative and positive terminals of the kilowatt battery (or remove the battery from the multimeter for testing) E (9V or 1.5V battery);
(4) If the pointer of the multimeter is deflected in the positive direction, the positive terminal of the battery and the negative terminal (black probe) of the multimeter have the same terminal. On the contrary, the terminal of the negative electrode of the battery and the terminal of the negative lead (black pen) of the multimeter are the same name. As shown in the figure, the first (or last) end is marked with a black dot, which means the end with the same name. Using the same method, determine the beginning and end of the other phase again.
Method 2: Star connection measurement method
Step 1: Determine the three-phase winding (the method is the same as above, note that after each phase is detected, simple and clear markings should be made to distinguish the three-phase stator winding).
Step 2: Star connection determines the first and last ends of the three-phase winding
Specific methods:
(1) Set the multimeter to microampere position;
(2) Short circuiting one end of each of the three windings of a three-phase asynchronous motor together with a red lead, connecting the other three ends together, and then connecting them with a black lead;
(3) Rotate the motor at a constant speed and observe the deflection of the pointer;
(4) If the pointer has almost no deflection, the three selected wire ends of each winding connected together are the same name ends (as shown in Figure 3). Otherwise, wire replacement adjustment should be carried out.
2. Line changing pattern:
(1) Mark the beginning and end of the three windings separately, and reserve the pin numbers.
(2) One set of windings (assumed to be terminals ⑤ - ⑥) is always fixed as the reference.
(3) After either of the other two groups is paired off, distinguish according to specific methods (1) - (4). If there is still deviation, then by aligning the head and tail of the other group and using specific methods such as "1) - (4)", the correct homonymous end can be identified.
