US999893A - Winding-coil for dynamo-electric machines. - Google Patents

Description

G. B. SKINNER.

- WINDING con, FOR DYNAMO ELECTRIC MACHINES.

APPLICATION FILED OCT. 7, 1908.

999,893; Patented Aug. 8,1911.

INYENTOR ATTO RN EY UNITED STATES PATENT orrIoE.

CHARLES E. SKINNER, OF 'WILKINSBURG, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, OF EAST PITTSBURG, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

WINDING COIL FOR DYNAMIC-ELECTRIC MACHINES.

Specification or Letters Patent.

To all whom it may concern:

Be it known that I, CHARLES E. SKINNER, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny are often constructed by winding copper strap or ribbon into arectangular helix, and since the voltage between turns in coils of this character is relatively low, strips of insulating material have usually been inserted between the turns of the helix in preference to wrapping the conductor with insulating tape or completely covering it by other means, in order to improve the ventilation of the winding. I a

According to my present inventioml employ metallfoil or very thin metal ribbon which has been so treated as to produce a hard film or coating of insulation on its surface. By this means, the space occupied by the insulation so produced is relatively small, since foil'of approximately one-thousandth of an inch in thickness may be employed, and, in addition to this advantage, the coil is rendered fireproof and capable of opera tion at high temperatures.

It will be readily understood by .those' skilled in the art that the electrical design of a coil to which the aforesaid insulation is to be applied, may be so modified as to effect a material saving in. the amount of copper required. p

Figure of the accompanying drawing is a perspective view of a coil constructed in accordance with my invention, and Figs. 2 and 3 are sectional elevations of the coil of Fig. 1 with insulating wrappings of heat.- conducting material applied thereto. Fig. 4 is a sectional elevation, on a larger .scale, of a portion of a coil disclosing a modified insulating structure embodying my invention.

Referring to the drawings, the coil here illustrated comprises a plurality of turns of conducting strap or ribbon, which, together,

constitute a substantially rectangular helix, the turns being wound on edge so that the flat surfaces of the ribbon are adjacent to each other. After the coil is formed of bare copper ribbon or strap, strips 2 of metal foil are interposed between the adjacent turns of the helix, said strips having first been treated to produce the insulating coating or film on their surfaces; ,The edges of the conducting strap of which the coil is wound are insulated by a close wrapping 3 of metal foil, similar to that employed be-' tween the turns of the helix, the necessary insulation being obtained by treating the foil as hereinafter pointed out and by employing any desired number ofoverlapping turns. The wrapping is bound 'as tightly as possible to the coil in order toimprove its eat-conducting properties by excluding films of air which, when heated, become poor heat-conductors. For mechanical reasons, the thickness. of the foilor'plate used in the wrapping 3 may be increased and the wrap ping built up ofoverlapping angle plates 4 arranged to telescope together, as shown in Fig, 3.

here the insulation is required to withstand relatively high voltages, sheets 5 of mica may be interposed between layers of the metal foil as shownin Fig. 4 of the drawings. 7

An insulating fabric constructed in the manner just referred to has the advantage of being fireproof, while the aluminum foil holds the mica flakes in position.

I prefer toemploy strips of aluminum foil of substantially one-thousandth (1/ 1000) of an inch in thickness, in order that a minimum amount of space may be-occupied by the insulation and in order that the fireproof insulating film may readily be formed on its surface. A specially good result may be obtained by passing the strip of aluminum through a bath of ammonium bora-te or some other suitable liquid and at the same time passing current through the electric conductor and the bath, thereby roducing an aluminum-oxid film which is 're latively hard, not readily destroyed byv heat, and at the same time affords adequate insulation for a considerable voltage which is far in excess of the voltage which usually obtains between adjacent turns of the field coils of a dynamo-electric machine.

Patented Aug. 8, 1911.

It will be readily understood that my invention is not restricted to any specific type or kind of coil, and I desire that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A fireproof coil for electrical apparatuscomprising a plurality of turnsof conductin material separated by metal foil treate to produce an insulating coating or film on its surface.

2. A fireproof coil for electrical apparatus comprising a plurality of turns of copper strap or ribbon and a suit-able strip or layer of metal foil interposed between adjacent turns, said metal foil being first treated to provide an insulatin film on its surface.

3. A fireproof coi for electrical apparatus, comprising a plurality of turns of confoil.

- In testimony whereof; I have hereunto subscribed my name this 21st-day of Sept, 1908.

CHARLES E. SKINNER.

Witnesses:

LILIAN I. JOHN, BIRNEY HINES.

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