Page 197 - Electrician - TT (Volume 2)

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The coil throw for main winding will be 1-9 and the winding table will be as shown in Table 3.

Table 3
Main winding - winding table

For the same group 1st pole 2nd pole 3rd pole 4th pole

1st coil 1 - 9 10 - 18 19 - 27 28 - 36
2nd coil 2 - 8 11 - 17 20 - 26 29 - 35
3rd coil 3 - 7 12 - 16 21 - 25 30 - 34
4th coil 4 - 6 13 - 15 22 - 24 31 - 33

Calculate the degrees/slot.

Total electrical degrees = 180 x 4 = 720 electrical degrees.
Degrees/slot = 720/36 = 20 electrical degrees
For phase displacement of 90 electrical degrees we require 90/20 = 4.5 slots. As it is impossible to start at 4.5
slots, let us start the starting winding in slot No.5.
Hence the coil throw for starting winding will also be 1 - 9, but it starts in the 5th slot. As such the winding table
will be as shown in Table 4

Table 4
Starting winding - winding table

For the same group 1st pole 2nd pole 3rd pole 4th pole

1st coil 5 - 13 14 - 22 23 - 31 32 - 4
2nd coil 6 - 12 15 - 21 24 - 30 33 - 3
3rd coil 7 - 11 16 - 20 25 - 29 34 - 2

There will be several slots having 2 coil sides and some slots may have single coil side only.
Remembering the whole coil connection, the connection diagram will be as shown in Fig 6.
Based on the above, the developed diagram is shown in Fig 7.

Fig 6

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CITS : Power - Electrician & Wireman - Lesson 86-92 CITS : Power - Electrician & Wireman - Lesson 86-92