Sections: Pole | Yoke & Ring | Field Magnet Coil

Pole Design

Item 50.7. Leakage Factor, l_f

Output of machine. kW	Leakage Coefficient
50	1.25 to 1.12
100	1.22 to 1.11
200	1.20 to 1.10
500	1.18 to 1.09
1,000	1.16 to 1.08
1,500	1.14 to 1.07
2,000	1.12 to 1.06

Refer to the table at right.
Common value use: 1.15.
For correction, after finalizing the pole dimensions.

Item 50.8. Maximum Flux Density in Pole Core at Full Load, B"g_c
Refer to the B-H curve of fig. 61.
Trial value: 90,000 lines per sq. in.

Item 50.9. Cross Section of the Pole Core, A_c
Use: A_c = F_FL x l_f / B"g_c

Length of Pole Core, l_core
Use: l_core = l_a - 1.5d
This is the length of pole core measured parallel to the shaft.

Width of the Pole Core, w_core
Use: w_core = A_c /l_core

Pole Ledge
Approximately about 1/2 inch.

Pole Tips
Usually rounded off with a radius of about 1/8 inch.

Flux Leaking from Pole Tip, F_tips
Use: F_tips = 0.25 x 0.15 x F.

Length of AB, length_AB
Use: length_AB = 0.5r t - w_core .

Flux Entering Armature Teeth in space AB, F_AB
Use: F_AB = (length_AB/ r t) x F .

Total Flux at x, Fx
Use: F_tips + F_AB.

Thickness of Metal at the Pole, x
Use: x = F_x / L_core x B"g_c.

Item 50.10. Length of Winding Space on Pole, d
Radial dimension of the pole must approximately correspond to that of the commutating pole.

Items 11 - 14

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