TransactionsPublished under the care of the General Secretary and the Treasurer . Fig. 38. Cast-Steel PoleWith Screwed-on liAMi-NATED Pole-Shoes. Fig. 39. Cast-Steel PoleWith Sceewed-on CastIron Pole-Shoes. poles are calculated in the same way as those of the mainpoles. For reversing the current the necessary field is This field must be provided in the commutating zone under thecompensating poles. Since the field is requisite only in the com-mutating zone itself, and since the coil sides are not equally dis-tributed over the armature periphery, but are concentrated in slots,. Fig. 40. Direct-C
TransactionsPublished under the care of the General Secretary and the Treasurer . Fig. 38. Cast-Steel PoleWith Screwed-on liAMi-NATED Pole-Shoes. Fig. 39. Cast-Steel PoleWith Sceewed-on CastIron Pole-Shoes. poles are calculated in the same way as those of the mainpoles. For reversing the current the necessary field is This field must be provided in the commutating zone under thecompensating poles. Since the field is requisite only in the com-mutating zone itself, and since the coil sides are not equally dis-tributed over the armature periphery, but are concentrated in slots,. Fig. 40. Direct-Current Machine With Commuta-tion Poles. the width of the compensating poles, in view of the lateral strayfield, is best made somewhat smaller than f^ -}- b^ — /?^ becausethe current in one slot is commutated over so wide a zone. First the ampere-turns, A TIV per circuit, are calculated whichare necessary to drive the flux ARNOLD AND LA COUR: COMMUTATION. 845 through the magnetic circuit C, of the compensating pole. Tothese are then added the total ampere-turns of the armature ^ . ^^Sper pair of poles which influence the same circuit. For two com-mutating poles we obtain, therefore, a number of ampere-turns AWn = A TFfc^ -{-T ASwhere t signifies the distance between pole centers. Hence, it fol-lows that all compensating poles receive a larger number of ampere-turns than the armature. It is necessary to observe that the lengthof winding is much less than that of the main pole, and that thenumber of ampere-turns of the main pole becomes smaller, becausethe brushes stan
Size: 2218px × 1126px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookidtr, booksubjectelectricity
