Connection of Double-Pole, Dual-Speed Windings

Commonly used for coils of double-layer windings are lap- and concentric-types. Single-speed double-layer winding electric machine is usually connected as whole-coiled winding. Double-pole, dual-speed electric machine is connected as double-layer, whole-coiled winding at high speed and as double-layer, half-coiled winding at low speed.

Take as an example a three-phase, dual-speed, 2/4-pole, 24-slot, double-layer winding. The arrangement of coils is shown in the Table and in the following figure.

Slot number

1

2

3

4

5

6

7

8

9

10

11

12

Two poles

A

A

A

A

–C

–C

–C

–C

B

B

B

B

Four poles

A

A

A

A

C

C

C

C

B

B

B

B

Slot number

13

14

15

16

17

18

19

20

21

22

23

24

Two poles

–A

–A

–A

–A

C

C

C

C

–B

–B

–B

–B

Four poles

A

A

A

A

C

C

C

C

B

B

B

B

The connection for variation of number of poles is shown in the next figure. On the top-left is the two-pole, 2Y-connection at high speed, on the top-right is the four-pole connection at low speed.