Use the figures and winding connections diagrams in the lesson on motor rewind to help identify the type of connection.

Connection. Determine the type of connection (this may have to be done after burnout). Carefully cut all lacing on the connection side of the winding. arefully pull all jumpers, all internal connections, and the line (T1, T2, T3, etc.) leads away from the stator winding.

Line leads will be stranded wire; motor leads are solid magnet wire

Locate points where the line leads connect to the stator winding and determine the number of stator winding (phase) leads connected to each. Inspect for star points formed where the finishes of the phases connect together. If you find star points, this indicates a wye or star connection.

If a star point is found, and there are two phase finishes connected to each line lead, inspect for another star point (denoting a parallel wye). If no star points are located and there are two phase leads connected to each line lead, a delta connection is indicated.

Enter the information in the space provided on the motor repair identification sheet.

Number of pole-phase groups (PPGs).Multiply the number of poles by the number of phases. Enter the information in the space provided on the motor repair identification sheet.

Number of coils per PPG. Divide the number of coils by the number of PPGs. Enter the information in the space provided.

Coil span or pitch. Coil span or pitch is defined as the number of slots separating the sides of the same coil including the slots in which the coil sides lie. Span is defined as the number of risers spanned by the coil.

If the stator contains a basket winding, determine the coil span or pitch at this time. If the stator contains a distributed winding, it is better and easier to determine span or pitch after burnout. Enter the information in the space provided.

Depending on the condition of the individual winding and connections, it may be better and easier to determine wire size(s)after burnout.

Wire size. Cut one line lead just below on the stator side of the soldered connection point to the phase lead. After removing the insulation film, use a gage to measure each wire that was connected to the line lead. To measure the wire without removing the insulating film, insert the wire into the slot that is approximately the size of the wire gage. If the wire fits loosely, go to the next smaller slot. Repeat until the wire will not fit in the slot unless forced. This slot is the size of the wire.

Turns per coil. This information will be obtained from the sample coil removed from the stator winding after burnout. Tie or tape the coil on one side. Cut the coil on the opposite side, tie or tape at either end, and separate the cut ends. Count the number of turns of wires in the coil. Divide the number of turns by the number of wires in hand, if applicable. Enter the information in the the space provided.

Determining the number of wires in hand information may be more easily and better obtained after burnout.

Number of wires in hand. Count the number of wires in any phase lead that was previously connected to a line lead. Enter the information in the space provided.

It is best to obtain the end room data before burnout.

End room (front and back). End room is defined as the distance the coils extend beyond the end of the slots. Front end room refers to this distance on the connection side of the stator winding.

Measure the end room with a steel rule. Enter the information in the space provided.

Lead wire size circular mil area (CMA). If the phase lead wire size and number of wires in hand are known, proceed as follows to determine CMA of lead wire required. Refer to the wire table for standard annealed solid copper wire to obtain the diameter of the phase lead wire in mils. Apply the following formula:

Total CMA = D² conductors in hand

Example:
The phase lead is number 22 gage wire, 5 in hand.
Diameter of 22 gage wire = 25.3 mils
25.3 x 25.3 = 640.09 x 5 = 3200.45 CMA

For delta-connected windings, you must multiply the total CMA by 1.73.

3200.45 x 1.73 = 5536.8 CMA

By referring to the table, you will see that the closest match of lead wire CMA, without being less than required, would be number 15 for a wye connection and number 12 for a delta connection.

One method of determining the size of lead wire requires that the horsepower, voltage, and type of winding connection be known. By applying this information to the lead wire table for motors, you can determine the size of lead wire to be used. Determine the size of the wire required and enter the size in the space provided.

Lead wire length. Measure the length of the lead wire. Enter the information in the space provided.

Winding connection diagram

When all information is obtained, draw a winding connection diagram. For basket-wound and single-phase motors, use the space provided on the right side of the motor repair identification sheet. For distributed wound motors, construct a straight line or circular winding connection diagram (discussed in the lesson on motor rewind).