. A text-book of electrical engineering;. Only those stator coils between B and D, subtending anangle tt (i — 2a) = 2877, need be considered, as the coils between D and Fare not linked with the flux produced by the rotor. Let Ti be the number of stator turns in series per pole-pair, Jg = c. Tj the number of rotor turns in series per pole-pair. 28—2 436 Electrical EngineertJig The maximum value of the flux density produced by a rotor current of I ampere will be B,= 0-477 ■ Tg where l„ is the double air-gap. This maximum value occurs at E in Figs. 432, 433, the flux densityfalling off unifo
. A text-book of electrical engineering;. Only those stator coils between B and D, subtending anangle tt (i — 2a) = 2877, need be considered, as the coils between D and Fare not linked with the flux produced by the rotor. Let Ti be the number of stator turns in series per pole-pair, Jg = c. Tj the number of rotor turns in series per pole-pair. 28—2 436 Electrical EngineertJig The maximum value of the flux density produced by a rotor current of I ampere will be B,= 0-477 ■ Tg where l„ is the double air-gap. This maximum value occurs at E in Figs. 432, 433, the flux densityfalling off uniformly on either side and reaching zero at the points C and we assume for the moment that the maximum flux density is unity andthat the motor is bipolar, so that each pole subtends an angle tt, we see that 2the flux density at any point in the air gap will he , where x is the angle between C and the point considered. A coil of width dx, as shown in thelower part of Fig. 433, will be linked by flux partly positive and partly. Fig. 433 negative, the resultant flux being equal to the shaded area, on the assump-tion that the motor has an axial length of i cm. Calling this flux O we have *=(-¥)-(i-)=i(-v:). dx The number of turns in series in this stator coil of width dx will be — .T,. TT The linkages will therefore be O dx •^^=t(^-V.)^- Now, to find the total stator linkages per pole-pair we have seen that weneed consider only those coils between B and D, that is from a; = — S77 toX = + Stt. Hence we have where 134 Single-phase Commutator Motors 437 Now, when we remember that the axial length is not i but L^, the maximum density not i but Bg = the pairs of poles not i but p, andD o4^ • ^2 la the pole-pitch not n but -^ times as great, we have M: 027r^ ^.T^ „ 10- 3 ------ l^ This is the mutual induction, but from it we can easily determine thecoefficient of self-induction of the stator, neglecting leakage, that is, neg-lecting the flux which links the
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