Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ...4Spec. U. S. Patent, 637,349. "Spec. British Patent, 5,530, April, 1899. the armature winding when the motor is started and replaced by the first mentioned winding when synchronism is attained. A general idea of the British T. II. Patent referred to, may be obtained by an inspection of Figure 72. This patent has to do with improvements in self-starting devices, by the introduction of certain combinations of inductance and condensance, or-of resistance and reactance in parallel with the motor across the mains. Fig. 72. Alexander Heyland" has devised a form of single-phase selfstarting motor. In this machine the chief winding is distributed in a set of slots, the leakage self-induction being reduced by having separate teeth over a considerable part of the periphery. The starting winding consists of closed coils wound in a bunched fashion so as to increase the leakage self-induction. A thin section of iron also bridges the slots holding these conductors. The currents induced in this closed winding, lag greatly and produce a cross field similar to another phase winding. His more recent work7 on the polyphase motor may have also some bearing upon single-phase work. oElec. Eng., Sept., 1897. Another interesting type of single-phase motor designed a short time ago by Prof. D. C. Jackson, consists of a rotor with two separate windings, one a commutated winding having resistance connectors joining successive segments of the commutator to avoid sparking, and the other, a winding short circuited through a variable resistance. In addition to being selfstarting the motor possesses the advantage of practically sparkless running, together with the possibility of running above, below, or at synchronism, depending upon the resistance inserted in...
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