I had some time today, so I finished the rewind and prepared the motor for dipping.
Inside an four pole wye connected induction motor there are four coil groups for each phase. These coil groups are connected with adjacent coil groups and the wye point. When connecting adjacent coils, the field direction (and thus the direction of DC current though the coil group) is reversed. Remember that opposites attract? That's how the magnetic field pulls the rotor around! Thus, it's imperative to know the polarity of each coil before making connections. If the connections are wrong after this stage they are very hard to correct.
To do this, I used a 9V battery and a child's compass. "Flashing" each coil group in succession with the 9V battery made the compass point towards or away from the coil group. If it showed north, I had the correct polarity. If the compass turned south, I knew I had the polarity reversed.
Referring back to the illustration I made a long time ago, there are 24 connections to be made. Since I'm winding this as a dual 240V-480V motor, I need to break out 9 leads. The remaining 15 connections are made internally in the motor windings:
All of the connections are made by cleaning the copper wire, twisting it together and "balling" it with a small oxy-acetylene flame. This is the preferred method as it is mechanically strong, exhibits a low resistance and will not weaken at the temperatures experienced within a motor core.
Once the connections are made, they are wrapped in fiberglass tube and the windings and their connections are bound up with fiberglass. The process is almost complete here, sans the three wires which make up the internal wye.
Inside an four pole wye connected induction motor there are four coil groups for each phase. These coil groups are connected with adjacent coil groups and the wye point. When connecting adjacent coils, the field direction (and thus the direction of DC current though the coil group) is reversed. Remember that opposites attract? That's how the magnetic field pulls the rotor around! Thus, it's imperative to know the polarity of each coil before making connections. If the connections are wrong after this stage they are very hard to correct.
To do this, I used a 9V battery and a child's compass. "Flashing" each coil group in succession with the 9V battery made the compass point towards or away from the coil group. If it showed north, I had the correct polarity. If the compass turned south, I knew I had the polarity reversed.
Referring back to the illustration I made a long time ago, there are 24 connections to be made. Since I'm winding this as a dual 240V-480V motor, I need to break out 9 leads. The remaining 15 connections are made internally in the motor windings:
All of the connections are made by cleaning the copper wire, twisting it together and "balling" it with a small oxy-acetylene flame. This is the preferred method as it is mechanically strong, exhibits a low resistance and will not weaken at the temperatures experienced within a motor core.
Once the connections are made, they are wrapped in fiberglass tube and the windings and their connections are bound up with fiberglass. The process is almost complete here, sans the three wires which make up the internal wye.
Last edited:
