Method for Using a Multimeter to Locate and Connect a Three-Phase Asynchronous Motor in Delta Configuration
Let's first define each phase group. Regardless of the number of poles of your motor, each group of coils has a "start" and an "end". Defining the "start" and "end" means that the directions of all coils are consistent according to the direction of the current. After connecting all the phase groups in series, there will be six wires left in the end, that is, each phase has a "start" and an "end".
We define the start of the first phase as number 1, the start of the second phase as number 2, the start of the third phase as number 3, the end of the first phase as number 4, the end of the second phase as number 5, and the end of the third phase as number 6. To ensure a phase difference of 120 degrees, we swap the definitions of the start and end of the second phase.
If the motor power is less than 3KW, we can connect the ends together to form a star connection. If the motor power is greater than 3KW, we need to connect the start and end in parallel to form a delta connection. The wiring sequence for the delta connection is as follows: connect 1 and 6 in parallel, which means connecting the start of the first phase and the end of the third phase in parallel; connect 2 and 4 in parallel, which means connecting the start of the second phase and the end of the first phase in parallel; connect 3 and 5 in parallel, which means connecting the start of the third phase and the end of the second phase in parallel. Then connect these three groups to the three - phase power supply respectively. This is the delta connection. If the motor has a six - terminal connection block, as shown in the figure below, after wiring according to the above definitions, simply connect them with copper strips as shown in the figure.
Use a multimeter to measure the DC resistance values of the three phase groups. They should be the same. Then find the starts and ends in the way described above. The three starts are on one side inside the motor, and the three ends are on the opposite side, which are easy to find.
The simplest method is to use the continuity testing function of a multimeter to measure the six wires pairwise. If there is continuity, it means they belong to the same winding. Find the starts and ends of the three groups respectively. For the same letter, 1 and 2 are the start and end. Then define the upper terminals as W2, U2, V2 and the lower terminals as U1, V1, W1. Refer to the sequence in the figure below.
