US1723839A - Electrical apparatus - Google Patents

Description

1929- r 1.. H. BURNHAM 1,723,839

ELECTRI CAL APPARATUS Filed Feb. 23, l928 Inventor: Locke H.Bur-nham, yW

His Attorney.

Patented Aug. 6, 1929.

* UNITED STATES PATENT OFFICE.

LOCKE H. BURNI-IAM, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOR TO GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK.

ELECTRICAL APPARATUS.

Application filed February 23, 1928. Serial No. 256,236.

My invention relates to electrical apparatus and more particularly to electrlcal apparatus having n'iagnetic cores with vertical winding legs. In devices of this character, insulating and supporting means for the winding or windings is necessary between the end winding turns and the core yokes and this insulating and supporting means has been found to interfere with efficient cooling of the end turns and the core yokes. The general ob ect of the IIIXeIlt-IOII is to provide an improved arrangement of insulating and supporting means between the end winding turns and the core yokes.

The invention will be better understood from the following description taken in con nection with the accompanying drawing in which Fig. 1 is a view on an encased oil immersed transformer, the casing being broken away to show means insulating and supporting the windings in accordance with the invention, Fig. 2 is a sectional view of the transformer on the line 22 of Fig. 1 and Fig. 8 is a sectional view on the line 3-3 of Fig. 2.

Like reference characters indicate similar parts in the different figures of the drawing.

The transformer shown in the drawing includes a magnetic core 10 having a vertical central winding leg, two vertical outer legs and horizontal top and bottom yokes connecting the ends of the vertical legs. The winding leg is surrounded by a high voltage winding 11 and a low voltage winding 12 so that each winding passes through the two openings or windows between the central winding leg and the two outer legs of the core. The axial dimension or length of each winding is somewhat less than the distance bet-ween the two core yokes and each end of each winding is spaced. from the adjacent yoke. An insulating and supporting means 13 for the windings is provided in each of the four spaces thus formed. Each I insulating support 13 includes a plurality of sheets or layers 14 of suitable insulating material with interposed spacing strips 15 so that spaces or ducts for the flow of a cooling medium such as oil is provided between the layers 14. The layers 14 are provided with openings as shown in Fig.2 connecting the spaces or ducts between the layers. It will be apparent that this arrangement provides paths for the cooling medium so that it may flow through the openings in the layers 14 and the spaces between them and also along the inner surfaces of the core yokes and the end surfaces of the windings opposite the yokes, these surfaces of the windings and yokes being thus efficiently cooled. The openings in the insulating layers 14 are staggered or offset in successive layers to avoid a direct path for an electrical breakdown or are between the windings and the yokes. In this way. the creepage path between the windings and yokes may be so great to require a greater voltage to break it down than would be required to puncture the insulating layers 14 in a direct path between the windings and yokes. The insulating layers 14 preferably extend at each side beyond the faces of the core as shown most clearly in Fig. 2, the outer edge portions of the layers being bent away from the adjacent ends of the windings so that they may interfere as little as possible with the flow of the cooling medium and at the same time provide insulation between the windings and the core yokes along the two faces of the core. The cooling medium, such oil having a high dielectric strength, in which the transformers is immersed may be confined with the trans former in a suitable casing 16 as shown in Fig. 1.

The invention has been explained by describing and illustrating a particular embodiment thereof but it will be apparent that various changes may be made without departing from the scope of the invention as defined in the appended claims.

\Vhat I claim as new and desire to secure by Letters Patent of the United States, is

1. An electrical apparatus including a magnetic core having a plurality of legs and yokes connecting the ends of said legs, a winding surrounding one of said legs, layers of insulating material between an end of said winding and the adjacent yoke and extending beyond the adjacent portions of their surfaces, and means for spacing said layers to provide ducts between them, the layers having openings therein connecting said ducts, and said layers being sufficiently offset in successive layers to make the leak age paths between said winding and yoke longer through said openings than the shortest direct distance between the winding and yoke.

2. An electrical apparatus including a lU-i magnetic core having a plurality of legs and yokes connecting the ends of said legs, a winding surrounding one of said legs, layers of insulating material between an end ofsaidwinding and the adjacent yoke, said layers extending beyond the two faces of said core and said extended ends being bent away from said Winding, and means for spacing said layers to provide ducts between them, the layers having openings therein connecting said ducts.

3. An electrical. apparatus includinga magnetic core having a plurality of legs and yokes connecting the ends of said legs,

a winding surrounding one of said legs, layers of insulating material between an end of said winding and the adjacent yoke, said layers extending beyond the two faces of said core and said extended ends being bent away from said Winding, and means for spacing said layers to provide ducts between them, the layers having openings therein connecting said ducts, and said openings being offset from each other in successive layers.

In witness whereof, I have hereunto set my hand this 18th day of February, 1928.

LOCKE H. BURNHAM.

Images