Dynamo-electric Machinery: A Manual for Students of Electrotechniques by Silvanus Phillips Thompson

Author:Silvanus Phillips Thompson
Language: eng
Format: epub
Publisher: Spon & Chamberlain
Published: 1905-03-25T05:00:00+00:00

FiG- 347.— Methods of CoNSTRUcriNfi Sloti'ed Rotors.

In order to get a perrectly cylindrical construction, which the Allgemeine Elektricitats-Gesellschaft of Berlin claim minimises the humming when rotating at high speeds, the

Fto. J48.— Rotor Construc

i Bullock Co.

construction shown in Fig, 349 has been adopted by them. Shaft and spider are in one piece of cast steel, C, and the former wound coils of strip copper are secured in position by the pieces B, B, which are let down into the dove-tailed slots

in the spider, and are then finally secured by the wedge D, which in its turn is prevented from flying outwards by the wedge E.

Revolving Armature Construction. For machines of A-type Mr. Parsons adopted, in 1896, a design having (for single-phase) the coils distributed in a number of closed slots below the periphery. One of the earliest Oerlikon plans (for a 2-phase machine) is shown in Fig. 314, p. 338, a 2-pole 20-slot winding, where the coils are threaded through closed slots, and the end-bends are wound under bronze projections, which abut against the

Fig. 349.—RoTOK Consthuction by the Allgemkine Co.

unwound parts of the core-disks. For a 3-phase armature the same firm developed the plan shown in Fig. 315, p. 339, which is a 4-slot 4-poIe winding.

Stator Construction.

The most special thing about stator-construction is the provision for circulation of air within the housing, as already alluded to. The Allgemeine Co. has used in some smaller turbo-machines the construction adopted for machines of older type, and shown in Fig. 166^, p. 182, in which the core-rings are mounted between circular checks without any casing to surround the outer periphery of the machine, thus exposing

to the cooling of the air the edges of the core-disks themselves.

A method of holding the end-bends of the armature-coils, as adopted by the General Electric Co. in the construction of their vertical-shaft Curtis turbo-alternators, is shown in Fig. 560, p. 475. The end-bends are threaded by straps of bronze bent to a U-form, which are solidly secured by the bolts that pass through the core-laminations and the core-heads.

Parsons's Turbo-Alternators.

As in the construction of steam-turbines, so also in that of generators to be driven by them, Mr. Parsons must be regarded as the pioneer. His first combined set of turbine and generator was built in 1884, and after use in Gateshead for several years was removed to South Kensington Museum. It ran at 18,000 RPM and developed about 7J KW in continuous current; the armature being 3 inches in diameter. The first turbo-alternator, built about 1888, had an output of 75 KW. In 1894 a turbo-alternator of 150 KW was installed at Portsmouth, and ran in parallel with other alternators of slow speed. About the same time others, of 350 KW, were supplied to the Metropolitan Electric Supply Co., at Manchester Square and elsewhere. Others of 500 KW were installed in Newcastle, Cambridge, and Scarborough. In 1900, Mr. Parsons constructed, for the town of Elberfeld, two sets of 1000 KW each, of 4-pole A-type running at 1500 RPM. They were found to consume only 19*43 lb.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.