US2107973A - Electric transformer for high tension - Google Patents

Description

Feb. 8, 1938. A BAJON ELECTRIC TRANSFORMER FOR HIGH TENSION Filed Sept. 3, 1935 Patented Feb. 8, 193 8 UNITED STATES PATENT QFFICE ELECTRIC TRANSFORMER FOR HIGH TENSION Adolphe Bajon, Gcntilly, France, asslgnor to Societe Anonyme "Transformateurs dc Mesure E. Walter, Gentilly, France, a corporation of France Application September 3, 1935, Serial No. 39,042

. In France December 29, 182*.

2 Claims.

Hitherto-the construction of such apparatus 5 has been attended with difllculties concerning the insulation oi the windings from one another or from ground. These difllculties are due to the lack of symmetry of the parts to be insulated, thus making it necessary to give complicated forms to'the insulating members, to the detriment of their dielectric properties. Various methods have been considered, up to the present, for obviating this drawback. The. dimensions of the magnetic circuit have been increased in 5 order to remove the windings from the unsymmetrical parts of thislatter. Use has also been made of a dielectric such as oil, which readily penetrates between the parts to be insulated and at once adapts itself to the most complex forms.

However, the first method leads to the use of very bulky and heavy apparatus which is not concement, while the use of oil does not lead to any great reduction of the sine, and it is always, with the great volume necessary, a source of serious danger from fire.

The present invention has for its object the construction of a transformer which does not offer these drawbacks. It is proposed to utilize for this purpose, instead of the closed magnetic m circuit which is in general use, an open magnetic circuit, which is symmetrical with reference to an axis. magnetic circuit carries windings separated is a condenser type insulating sleeve having metallic facings whichare connected to different points of the windings. The dielectric of the condenserv further assures the insulation of the windings from ground.

I .lhe invention wiil he better understood with reference to the accompanying drawing.

llieure 1 shows a constructional form oi? trans icrmer of the high-tension type.

Figure 2 is a diagram of the arrangement of the transformer.

Figure shows the arrangement of the plates dug the marinated core of the transformer.

.ieure represents the application oi the in a high urinal conor. open magne c circuit eight, an has a cylindrical form. As luctance of circuit is very high, an en larged part is provided at the base in order to reduce the reluctance, but the top part cannot comprise a like enlargement, owing to dimculties in the insulation. Immediately around this magnetic circuit is the low-tension winding C, which is insulated from the high-tension winding E-h' an insulat- 5 ing sleeve member I) having an i outer surface arranged coaxially with the magnetic circuit. The inner surface of the high-,

with the facing parts will be better understood with reference to Figure 2. In fact, the use of condensers connected as shown in Figure 2, has for its object, on the one hand, to compensate the increase oi. current at no load which is due to the open magnetic circuit, as the reduction of 5 this current is advantageous, and on the other hand, to facilitate the distribution, upon the winding, of surges which may come irom the exterior, such as may be caused by lightning, or the like.

The core it consists of radial plates arranged in groups, as shovm in Figure 3, which represents a cross-section of the magnetic circuit, in order to reduce the loss in the iron due to eddy currents. A It will thus he observed that the construction of this transformer oifers numerous advantages, due to the combination of a straight open magnetic circuit, with an insulating member provided with metallic facing parts, providing units of a con denser.

in fact, the use cl 2. straight magnetic circuit facilitates the insulation of the high-tensiorr winding, by to the dielectric very simple form. that of a circular tube, without making it necessary to increase the dimensions of the 4;; as of the separates. Thus a solid dielectric he used, the some tim obtaining" insulat could it he as 'ag'eous to use cilltate the mg, for error tanner may eed in a cylin u insulating mater: diameter only slightly greater than that of windings, and this will only require an em emely small amount of oil. I

ill

This arrangement is particularly advantageous in a high-tension transformer, as its general size is proportional to the tension, whereas in apparatus with closed magnetic circuit employing oil, the size will vary about as the cube of the tension.

The progressive distribution or the difierences of potential in the high-tension winding may be extended to adjacent apparatus. It is particularly applicable the distribution of the tension upon the terminal end of a cable P serving to supply the transformer, and for this purpose it is simply necessary to carry out the arrangement shown in Figure 4-, which represents the possible connections between the facing parts :1 which mounted on the cable, and the winding E oi ansforrner.

e character cs of ti s apparatus, as measuring transrcr :r, are as follows:

no-load current is smali.

accuracy is considerable.

e of th urrent at no load is the arrangement of the plat% I the core, as shown in Figure 3; (c) by the use of condensers connected as shown in Figure 2.

It is shown in the preceding considerations that on the one hand, this apparatus possesses, in addition to its own advantages, many of those of transformers with closed magnetic circuits and has few or the disadvantages of transformers with open magnetic circuit, in which the degree of accuracy can only be a very small fraction of the apparent power absorbed at no load, as such apparatus has either a very low degree of accuracy or a very large current at no load.

I claim:

1. In an electrical high tension support type transformer, an open magnetic clrcuitdron core having a bar-like vertical portion and alsupporting base portion adapted to be grounded, a low voltage winding arranged along the bar-like portion of the core, a high voltage winding having a generally conically shaped interior surface arranged over the low voltage winding, a plurality of insulated metal cylinders in stepped coaxial arrangement between the high and low voltage windings to provide capacity elements of a condenser, the inner cylinders being of greater length than the outer cylinders to substantially fill the space between the two windings, the area of the outermost cylinder equalling at least onehalf of the area of the innermost cylinder, and all of said cylinders extending beyond the two windings at the upper end thereof and the outer cylinders projecting beyond the upper end of said core.

2. In an electrical high tension support type transformer, an open magnetic circuit iron core having 5. her-like vertical portion and an eniarged supporting base po t on adapted to be grounded, a low voltace w ring arranged along the bar-like portion of the core, a high voltage winding having a generally sonically shaped interior surface arranged over the low voltage winding, a plurality or insulated metal cylinders in stepped coaxial arrangement between the hgh and low voltage windings to provide capalty elements-of a condenser, the inner cylinders being of greater length than the outer cylinders to substantially fill the space between the two windings, the area of the outermost cylinder equalling at least one-half the area of the innermost cylinder, all of said cylinders extending beyond the two windings at the upper end thereof and the outer cylinders projecting beyond the upper end of said core, and the successive outer cylinders projecting beyond each preceding inrcr cylinder.

ADOLPHE BAJOF'

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