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US Patent: 1,566,939
Dynamo-electric machine
Patentee:
Alfred F. Welch (exact or similar names) - Fort Wayne, IN

USPTO Classifications:
310/180, 318/778

Tool Categories:
electrical devices : electric motors : induction motors

Assignees:
General Electric Co. - Schenectady, NY

Manufacturer:
General Electric Co. - Schenectady, NY

Witnesses:
Unknown

Patent Dates:
Applied: Nov. 13, 1923
Granted: Dec. 22, 1925

Patent Pictures: [ 1 | 2 | 3 ]
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Vintage Machinery entry for General Electric Co.
Description:
"My invention... has for its object a novel construction of one of the members of such a machine whereby the magnetic material of the member is used to better advantage than was heretofore possible and the available space for the winding of the member is materially increased. Although my invention is applicable to dynamo electric machines generally, it is particularly applicable to single phase alternating current motors of the induction type provided with starting windings. A motor of this type has a nearly uniform revolving field, so that for best operation its field should present a uniform magnetic permeance for each unit element of the air gap periphery (represented usually by a tooth, where the teeth are equiangularly spaced). However, the main running winding is concentric with a larger number of turns in the outside than in the inside coils of each pole, and the starting winding requires only a very small area, part of which is arranged in slots left unfilled by the main winding. The slot area required is therefore not uniformly distributed around the periphery. Such a motor therefore requires a uniform distribution of peripheral iron cross section and a non-uniformly distributed winding... I shape the slots so that their area is such as to be filled with the winding and at the same time preserve a substantially uniform magnetic permeance."

This patent date was seen on a GE model 26136 motor, which is a 147 frame, quarter horsepower induction motor with the power applied to the rotor, (the usual induction motor has power applied to the stator, not the rotor) via brushes and slip rings. In a 1930 GE catalog it says, "The Type SA motors are designed with the primary or field winding on the revolving member of the rotor."

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