Alternating currents of electricity; their generation, measurement, distribution, and application

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. 1893 Excerpt: ...with side wings for ventilation. The attachment of each pair of cheeks to the supporting ring is by means of a shank passing through insulating washers into a cavity in the ring, and secured by a nut. The cavity is cast out with sulphur. To avoid too great a loss by eddy currents the conductor is made very thin; the winding is split up into two, four, or more parallel circuits. I may here incidentally mention that where an armature winding is thus split up, great care must be taken to have all the magnets of equal strength, as otherwise there would be created with the armature differential currents, which would waste far more power than the eddy currents, which the arrangement was intended to avoid. The Ferranti machines now working at Deptford are giving an electromotive force of 10,000 volts, and to prevent flashing over to the magnets the latter are provided with double caps of ebonite. 2. The Mordey Alternator.--This is also a coreless machine of the disc pattern, but the armature is fixed whilst the magnets revolve. The armature coils (Fig. 22) are wedge-shaped, and the conductor is a thin copper strip wound on a slate core, the layers being separated, as in the Ferranti coils, by a thin strip of insulating material. The attachment is made at the outer and wider end of the coil to a gun-metal supporting ring. The magnets are of cast-iron, and so shaped as to require only one coil C of exciting wire. This is wound on a central cylindrical part y, to both sides of which are pole pieces of peculiar star-like form. Thus the poles on one side of the armature are all of the same sign, and those on the other side are of the opposite sign, the lines of force passing from N to S at right angles through the surface of the armature, and all in the same direction....