<-- Back Items 27 - 32

Item 33. Weight of Iron in Core (Without Teeth), Wt_core
Wt_core = 0.28 × l_n × [ p × ( R_a² - R_s²) - CS_AD ].

Item 34. Weight of Iron in Teeth, Wt_teeth
Wt_teeth = 0.28 x l_n × [p × ( R_s² - r²) - (S x s x d )].
Wt_teeth = 0.28 x l_n × [S × d ×t_ave].

Item 35. Total Core Loss, incl. Teeth (open circuit), KW, W_sfe
W_sfe = W_core + W_teeth

Core Loss, (open circuit), KW, W_sfe
W_core = w/lb x + Wt_core
W_teeth = w/lb x + Wt_teeth
For iron-loss per pound, refer to Fig. 67, using the approximate flux densities for B"g_core and B"t from item 30 and item 31. Remember that Fig. 67 gives the watts/pound/cycle, reduced by 20%.

Item 36. Length mean turn of armature winding, m.l.t.
m.l.t. = 2l_a + 2.5t + 2kV + 6
Add 5% of length at end of turns for safety.

Cross Section of Conductor, sq. in, CS_{sq. in.}
CS_{final in sq. in.} = a x t_c x w_c.

Cross Section of Conductor, Circular Mils, (m)
(m) = (4/p) × (CS_{final in sq. in}) x 10⁶.
Where: CS_{final in sq. in} is Item no. 27.

Turns per Phase, T/f
T/f = Z' / 2 .

Item 37. Resistance per Phase, ohms, at 60°, (R/f)
(R/f) = m.l.t. × (T/f) / (m).

Item 38. IR Drop per phase (FL Current), volts, IR/f
IR/f = (R/f) x I_c
Add 5% for the effect of eddy currents in the conductors.

Item 39. Total Armature Copper Loss (FL Current), KW, I²R/f
I²R/f = 3 x I_c² x (R/f)
Add 50% to cover sundry indeterminate load losses.

Items 40 - 43

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