Background

Proper coil insertion in a stator requires adequate insulation for the coil sides. Since any electric circuit must be mechanically as well as electrically sound, the risk of damage during installation must be minimized.

Preparation for coil insertion

Carefully lay out previously prepared insulating materials, pole-phase groups (PPGs), and required tools.

Place the stator in a stator holder and secure.

Insert the protective paper liner.

Insert slot cell insulator in the slot where the first coil side will be installed (slot 1). Spread the two sides of the insulation to make coil insertion easier.

Lay out a PPG next to the stator with the leads and crossover near the side of the stator where the connections will be made.

Coil insertion

For the procedure below, the leads will be on the correct side of the stator.

Pick up a coil by the end farthest from the stator and end over end the coil through the stator bore.

Carefully remove the twine from the coil side that will be installed in the first slot.

Flatten the coil between the thumb and index finger of each hand, fanning the wires into parallel rows, and feed the coil into the slot.

Press the ends of the coil down into the slot to clear the stator bore.

Insert a coil side separator over the coil side.

The installation of one slot cell insulator at a time will greatly reduce the chances of skipping a slot. Also, there is less chance of injuring your fingers or hands by cutting them on additional installed slot cell insulators.

Continue to install one slot cell insulator, one coil side, and one coil side separator until one span is completed.

Allow the sides of the coils of the first span to rest on the protective liner.

After one span is laid in, install the next PPG by putting one coil side in an empty slot, and the other side into a slot with a coil and a coil separator. Tamp the flat coil separator down tightly with a tamping wedge before putting a second coil side in a slot.

The temporary slot stick must project over the ends of the coil to protect it from the cutting tool.

Insert a temporary fiber slot stick (wedge) to hold wires in place on top coil side.

Cut the excess slot cell insulation flush with the stator iron using a slot cell insulation cutter.

Remove the temporary fiber slot stick by pulling it out of the slot.

Fold the two sides of the slot cell insulation over each other. Insert a slot wedge over the folded slot cell insulation.

As each PPG is inserted, install triangular sheets of phase material to separate the phase groups.

Ensure that the phase material butts against the slot cell insulation in the stator bore.

Trim the phase material to within 1/4 inch of the coil ends.

Continue to insert coils, using slot cell insulation, coil separators, temporary slot sticks, slot wedges, and phase material until all the coils are installed in the stator.

Remove the protective liner when coils must be installed under the coils first laid in.

Lay in the top coils of the first span when all the bottom slots have been filled.