Item 57. Approximate Air Gap Clearance, d
Use: d_trial = (D + 15 ) mills
Use: d_final = (d_final + 2 ) mills

Item 58. Equivalent Air Gap, d_e
Use: d_e = p × D / [ pD - ½ × 0.85 (S_Aw_A + S_Rw_R ) ]
Where: D = Stator Internal Diameter.
S_A = Number of Stator Slots.
w_A = width of opening at Stator Slot.
S_R = Number of Rotor Slots.
w_R = Width of opening at Rotor Slots.

Item 59. Maximum Ampere-Turns per pole in Air Gap, (TI)g
Use: (TI)g = 0.313 ( p/2 × B"ave_final ) d_e

Item 60. Magnetizing Component of Exciting Current, Io

HP	Io/Ie	HP	Io/Ie
20	0.30	150	0.23
50	0.27	200	0.21
100	0.25	250	0.19

Use: Io = m × 1.095 × ( p × B"gave_final × d_e ) / 3Z
Where: m = 1.2 to 1.4 with a common value of 1.33.
Item 60a. Ratio Io/Ic
Compare this value to Article 11.2, page 311.
Interpolate for other HP.

Item 61. Total No Load Losses, SL_NL = W_NL
Use: SL_NL = W_NL = W_{A fe} + W_{R fe} + W_cu + W_WF
Where: W_{A fe} , Armature Iron Loss, Item 39.
W_{R fe} = 0.05 × W_{R fe} .
W_cu = 3 × (1.01 Io² ) (R/f).
W_WF , Friction and Windage Loss, Item 56e.
1.01 Io, Estimated Primary Current.
(R/f), Resistance per phase, see Item 30.

Item 61a. In-phase Component of Exciting Current, Iw
Use: Iw = SL_NL / 3E = W_NL / 3E

Item 62. Total Exciting Current, Ie
Use: Ie = ( Ie² + Iw² )
Compare to the ratio Io/Ie = see Item 60a, and Article 112.

Item 63. Power factor with motor Running Light ( No Load), cosq_NL
Use: cosq_NL = Iw / Ie.

Leakage Flux - Permeance: Items 64 - 70

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