xvi LIST OF PRINCIPAL SYMBOLS 



Symbol. Meaning. P^. whjedjjned 



la, 1 Gross armature length 90, 102 



/, Semi-net armature length 220 



In Net armature length 102 



L I nductance 184 



m Number of phases 69 



M Magnetomotive force 7 



M a M.m.f. of armature 144 



Ma M.m.f. of direct reaction 153 



M f M.m.f. of field 144 



M n Net m.m.f 144 



M t M.m.f. of transverse reaction 153 



MI Demagnetizing m.m.f 165 



M, Distorting m.m.f 166 



n Number of turns 127, 211 



TI, N! Number of turns in primary of a transformer 62, 81 



JVj Number of turns in secondary of a transformer 62 



N Total turns in series 65 



O m Mean length of turn 211 



p Number of poles 133 



P Power 48 



(P Permeance 9 



(P a Permeance of air-gap 89 



(Pa Equivalent permeance around conductors in the ducts per cm . . 220 



(P c Permeance of the path of the complete linkages 182 



(Pe Equivalent permeance around the end-connections per cm 220 



(Peg Equivalent permeance 184 



(Pi' Equivalent permeance around embedded conductors per cm ... 220 



(Pp Permeance of the path of the partial linkages 182 



(P s Permeance of simplified air-gap 90 



(P z Zig-zag permeance 223 



q Number of sections in a transformer 213 



q Number of turns per commutator segment 235 



r, R Resistance 51, 177 



(R.P.M.) Speed in revolutions per minute 260 



(R Reluctance 7 



s Distance 244 



s Number of coils short-circuited by a brush 236 



8 Slot width 93 



S Number of slots per pole per phase 68 



S Surface area 244 



t Thickness of laminations 51 



t Time 9 



t Tooth width 93 



t' Tooth width corrected 93 



T Time of one cycle 64 



T Torque 253 



