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Title: |
1895 Article-Ayrton & Perry, Electric Motor |
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Source: |
Modern Mechanism 1895 pg 540 |
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Insert Date: |
8/30/2011 9:41:18 PM |
Professors Ayrton and Perry, of England, have devoted much attention to the study of electric motors, and have promulgated the theory that, whereas in the dynamo the field should be of great magnetic strength and the armature a weak one magnetically, the reverse should be observed in the motor—i.e.. the field should be a weak magnet and the armature a powerful magnet. This theory, however, has not been sustained by practical experience. They embodied their ideas some time ago in a form of motor which differs from those of ordinary construction in that the armature is kept stationary while the field magnet revolves within it.
Fig. 2 shows the Ayrton and Perry motor in perspective ; Fig. 3 shows the construction of the motor more in detail. The stationary armature, as will be seen, consists of a laminated cylinder built up of toothed rings of sheet-iron, and resembles very much the Pacinotti toothed-ring armature. The wires are wound on in sections, joined iii series, and at each joint are connected to a segment of the stationary commutator. C C. The spindle of the revolving field magnet carries the brushes, which revolve with it.
In explanation of the operation of the motor, Professor Ayrton says that wherever the brushes, B, happen to be at any particular moment, there two opposite magnetic poles, at A7 and 8, are produced on the armature, as shown in Fig. 3. As the brushes revolve, so do these poles, and the brushes, which are carried by the field magnets, are so set that the magnetic poles in the armature are always a little in front of those in the field magnet. The latter, therefore, are, as it were, perpetually running after the former, but never catching them. From the peculiar construction of the Ayrton and Perry motor, it may be operated without any wire at all upon the revolving field magnets. This arises from the fact that the magnetism in the stationary armature induces opposite magnetism in the iron of the field magnets, and, as pointed out before, the brushes are so placed that the magnetic poles in the armature are always just in front of those in the iron, which latter are always running round after those in the former, but never catch up with them. |
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