The Theory, Design and Working of Alternate-Current Motors

by Llewelyn Birchall Atkinson

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1898 ...of such a machine, on account of its dual function of a 3-phase motor and a commutating dynamo, is higher than in a machine of equal output having a single function. The effect of the current in the armature of a rotary converter may be determined by considering the machine, first, acting as a simple 3-phase machine, and secondly, as a continuous-current dynamo. Superimposing the conditions obtaining in the first condition on those obtaining in the second, it will be found that the resultant current in all the conductors of the rotary converter is less than is the case either with a 3-phase machine or a dynamo; consequently the heating of such a machine when operated as a rotary converter is less than when operated either as a 3-phase machine or dynamo. The reactions of the magnetism due to the current in the armature add together in such a way that the resultant interaction in the rotary converter is greatly less than when acting either as a dynamo or a 3-phase generator; consequently the distortion in the air-gap is small, and change of lead for varying load becomes negligible. The advantages of the rotary converter may be pointed out at length, since in installations differing only in magnitude from the original Dublin installation, as at first laid out, the rotary converter becomes by far the most desirable and economical machine. In large installations where 200-kilowatt machines or larger can be economically used for conversion, there is no question as to the greater efficiency and advantage of the use of rotary converters. In the present installation, however, the machines were of 75-kilowatt capacity, so that small reducing transformers would have to be used. These transformers are not so easily repaired as a synchronous motor. Further, to allow for...

146 pages, Paperback

Published July 18, 2023