The method of multimeter to judge the same name end of three-phase asynchronous motor winding
Method 1. Triangle connection assay
Step 1: Set the multimeter to R×100 gear, and measure the six outgoing wires of the motor junction box, two and two, respectively, to determine the three-phase winding.
The specific method: connect the red (or black) test lead to one of the lead wires; the black (or red) test lead contacts the other five lead wires in turn; the two outgoing ends of the channel (refers to larger deflection and smaller resistance) are one phase , and make a mark (it is recommended to use knotting or coloring as an identification mark) to distinguish it from the following two phases, and so on, divide the six lead lines into three groups (as shown in Figure 2).
Step 2: Set the multimeter to the current micro-ampere block, and check the wiring as shown in the figure to determine the head and tail ends of the two-phase windings.
specific method:
(1) Set the multimeter to the current microamp;
(2) The red and black test pens of the multimeter are connected to the two ends of one of the windings of the motor; from: Home of Electrical Technology
(3) Then contact the two terminals of the other phase of the motor successively with the negative and positive electrodes of the battery (or take out the battery in the multimeter for testing) E (9V or 1.5V battery);
(4) If the pointer of the multimeter is deflected in the positive direction, the terminal connected to the positive terminal of the battery and the terminal connected to the negative terminal of the multimeter (black test pen) are the terminals of the same name; otherwise, the terminal connected to the negative terminal of the battery and the terminal connected to the negative terminal of the multimeter (black test pen) are the terminals of the same name. The same name end; as shown in the figure, it is marked with a black dot as the head end (or tail end), which is the same name end. In the same way, determine the head and tail of the other phase.
Method 2: Star junction assay
Step 1: Determine the three-phase winding (the method is the same as above, note that after each phase is detected, a simple and clear sign should be made; in order to distinguish the three-phase stator winding).
Step 2: Star connection to determine the start and end of the three-phase winding 1.
specific method:
(1) Set the multimeter to the micro-block;
(2) Short-circuit each end of the three windings of the three-phase asynchronous motor together to connect the red test lead, connect the other three ends together, and then connect to the black test lead;
(3) Rotate the motor at a constant speed and observe the deflection of the pointer.
(4) If the pointer is hardly deflected, the three wire ends selected by each winding connected together are the same name ends (as shown in Figure 3). Otherwise, it should be adjusted by changing the line.
2. Line change rule:
(1) Mark the head and tail of the three windings respectively, and predetermine the terminal numbers.
(2) One group of windings (assumed to be the ⑤-⑥ end) is always fixed and used as a reference.
<3) After the head and tail of any one of the other two groups are matched, judge according to the specific methods (1)-(4). If there is still deflection, the end of the other group will be reversed, and then judged according to the specific method "1)-(4), and the correct end of the same name will be judged.
Attached, the junction box diagram of the star and delta connection of the stator windings UI-U2, V1-V2, W1-W2 of the three-phase asynchronous motor is shown in Figure-1. The broad curve shows that the star connection of the three-phase asynchronous motor is the fixed hand winding. The head end (or tail end) of the three-phase asynchronous motor is connected with each other; and the delta connection of the three-phase asynchronous motor is that the head end of the stator winding of one phase is connected to the tail end of the stator winding of the other phase. That is to say, whether it is a star connection or a delta connection, when repairing the motor, the key is to first determine the three-phase fixed-hand winding and its head and tail ends of the three-phase asynchronous motor. The author combines his own teaching practice experience and summarizes two kinds of rapid use of multimeters. A method for effectively judging the head and tail ends of three-phase asynchronous motor windings.
