Page 196 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS ELECTRICIAN - CITS

Calculation of electrical degrees required for phase splitting

Total electrical degrees = 180 x Total number of poles
= 180x4= 720 electrical degrees
Degrees/slot = 720/24 = 30 electrical degrees
No. of slots required for 90 electrical degrees dis-placement between main and starting winding = 90/30 = 3
slots.
Hence if the main winding starts in, say, slot number one, then the starting winding should be started in 1+3 = 4th
slot.

Computing the above information in a winding table we have Table 2.

Table 2
Winding table

Slot position for poles

Winding I pole II pole III pole IV pole
Main 1 - 6 7 - 12 13 - 18 19 - 24

2 - 5 8 - 11 14 - 17 20 - 23

Starting 4 - 9 10 - 15 16 - 21 22 - 3

Remembering whole coil connection the connection diagram is to be drawn as shown in Fig 4.
Remember ‘S’ is for starting and ‘E’ for end connection.
Based on the winding table the developed diagram is drawn as shown in Fig 5.

Fig 4 Fig 5

Example 2 : Prepare the winding table, draw the connection and developed diagrams for a single phase, 4-pole,
whole coil connected capacitor motor having 36 slots 28 coils (16 coils for main and 12 coils for the starting
winding).
Coil per group in main winding 16/4=4 coils/group/poles
Coil per group in starting winding 12/4 = 3 coils/group/poles

Number of slots 36
Pole pitch - 1 1 - 9 - 1 8
Number of poles 4

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