. Practical wireless telegraphy; a complete text book for students of radio communication . re is shown. In this diagram, an armature having 18 conductors revolves in a four pole field and theflow of current will be observed to have the following direction. If we start from com-mutator segment I, the point where the current enters the armature through the negativebrush, then the current flows through conductor 17, to commutator segment A, through con-ductors I and 6, and out at segment B. Tracing in the opposite direction, current flowsthrough 2, through 15 to segment H, through 18 and 13 and
. Practical wireless telegraphy; a complete text book for students of radio communication . re is shown. In this diagram, an armature having 18 conductors revolves in a four pole field and theflow of current will be observed to have the following direction. If we start from com-mutator segment I, the point where the current enters the armature through the negativebrush, then the current flows through conductor 17, to commutator segment A, through con-ductors I and 6, and out at segment B. Tracing in the opposite direction, current flowsthrough 2, through 15 to segment H, through 18 and 13 and finally comes out at G. Thecurrent is thus seen to take two paths from the negative brushes through the armature coilsto the positive brushes. And it will be clear also that one side of a given armature coil liesunderneath a north pole and the opposite side underneath a south pole 90° distant. Thestudent should note carefully the direction of the flow of current in all coils of the armaturewinding, taking particular note of the fact that in parts of the armature, the current is flowing. Fig. 32—Development of Lap-Wound Armature. towards the positive brushes and in other parts, away from the negative brushes. The coilscomposing the armature winding are connected so that the voltage induced jn one adds on fothat of the next coil, hence, current flows in the same general direction through variousgroups of coils although the sides of a given coil are under magnetic fields of opposite polarity. It is to be noted that the brush shown in Fig. 32 short circuits a particular coil of thearmature, which lies in the neutral magnetic Held. It is self-evident that if a given armaturecoil were short circuited by a brush when the coil occupies a position other than the neutralposition, it would be surrounded by a magnetic Held and current of great strength would beinduced therein. This would overheat or melt the conductors or at least would cause destruc-tive sparking at the commutator. If
Size: 2136px × 1170px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
