Start and End of Motor Windings

As mentioned in the previous post, you may end up with a motor that has 6 leads dangling from the terminal box and they are no longer numbered. Your task is to test the motor and prepare it to be put back in production. This may seem a bit daunting but it is actually quite easy to do.

Before you start with anything on the numbers, perform the motor test as per the previous post. To do this test for the Electrical side, just group your windings in pairs and don’t worry about which is one and which is two. Just find the pairs by testing the continuity of the windings with your Insulation Tester and remember to use it on the Ohm Scale. Once you have the pairs grouped, you can complete the Motor Test and move on to the next step of identifying the start and end of each winding.

You will need a 12V car battery (my preference) and an analogue multimeter for this step.

Connect a red wire to the positive of the battery and a black wire to the negative. Make sure you don’t touch the ends together! Now swap the leads on your meter the wrong way round i.e. Red into the black socket, and black into the red socket. If your meter leads are permanently connected, just mark the ends with some red and black tape. (Red tape onto the black lead, and black tape onto the red lead.)

What we will do now is to state that we call the red leads number one and the black leads number two. Connect the other end of the meter leads to any one of the winding pairs and make sure you have your meter set to measure DC Voltage

Now for the fun part. Hold the black lead on one end of another winding pair and touch and remove the red quickly. This will induce a voltage into the other windings and you will note a very quick deflection on your meter. If the deflection is positive, you have the numbers correct. If the meter deflects to negative, the numbers should be the other way round. Mark the motor leads at the battery pair one and two and do the same for the winding just tested. Using the same winding for the battery, perform the test on the remaining winding.

Well done! You have just paired the windings and established the beginning and end of each using some very inexpensive gearJ

Just remember to always swap the meter leads over when doing this as the induced voltage is in the reverse direction.