US1901767A - Lightning or surge absorber - Google Patents

Description

March 14, .1933. I O RIS 1,901,767

LIGHTNING OR SURGE ABSORBER Filed Oct. 19, 1929 5 p. y. mm;

Patented Mar. 14, 1933 :UNITED STATES PATENT OFFICE ERIC DOUGLAS TOBIAS NORRIS, OF HOLLINWOOD, ENGLAND, A INC 01' NEW YORK, N. Y.

assrenon: r rnan'amu LIGHTNING OR SURGE ABSORBER Application filed October 19, 1929, Serial No. 400,957,-and in Great Britain December 6, 1928.

This invention relates to lightning or surge absorbers of the type embodying a primary element comprising a winding for connection in series with the line and a metallic element associated with said wind- The winding andthe metallic element associated therewith may be regarded respectively as the primary and short-circuited secondary of a transformer.

Hitherto it has been the general practice to construct such devices in cylindrical form with cylindrical coils, providing the casings in the'larger sizes with radial coolin .fins.

Such devices may be oil filled or ry as desired.

Now I have found that with such constructions as contain oil provision must be made for the expansion and contraction of the oil with temperature changes. The provision of conservators with breather devices as is customary in electric transformer practice is undesirable since lightning or surge absorbers are usually mounted up a pole and are comparatively inaccessible.

Oil is desirable for two reasons, viz, for insulating purposes where the voltage is not fairly low and for heat dissipation purposes where the current is appreciable.

One object of the present invention is to provide constructions wherein the necessity for such conservator and breather device in oil-filled surge absorbers is avoided. Another object is to provide improved constructions both of the oil filled and dry type.

Referring tothe accompanying diagrammatic drawingz- Figure 1 illustrates a side view of one convenient construction in accordance with the present invention. 7

Figure 2 illustrates a horizontalsectionalview thereof.

Figure 3 illustrates, a vertical sectional view of a modified construction.

one convenient form -illustrated by way of example in Figures 1 and 2, I provide two fiat spiral line coils a, b separated by a sheet or sheets of insulation material a and disposed within a' substantially square flat castion conditions do not impose a limitation lig In carrying the invention intoefiect ing (2?, a layer or layers of insulation material g being interposed between the casing sides and the coils. Connecting leads are taken from the outer ends of the two coils respectively through diagonal corners of the casin and the coils are connected together electrically at their centres at 1'.

i The casing is provided with a suspension ring 6 at one of the remaining corners and is completely filled with oil. The space at 60. the centers of the coils is filled by inserting a disc or discs of wood 0.

According to this construction expansion and contraction of the oil is taken care of by the sides of the casing d which act as ex- Q panding diaphragms. Thus, the necessity for a conservator and breather device is avoided. I Furthermore, very little oil is required in comparison with that needed in the single to layer cylindrical type of sur e absorber and this is further reduced by t e provision of central disc or discs 0.

Also, there is no large waste space, as is the case in the ordinary cylindrical type 15 of absorber. Overall bulk is thus considerably less, with decrease in cost.

Again, owing to the comparatively small dimensions in the horizontal direction erecon the design, 1

Again, a primary winding embodying-elements having a plurality of layers in one plane is more eifici'ent as an inductance than a coil of the single layer cylindrical type. Thus, for a given inductance value less material is re uired than in the latter.

Again, since the external leads f are brought out from substantially the same plane as the coils their insulation is of extremely simple nature.

A similar form of construction ma be employed in respect of a non-oilled tning or sur e absorben.

Asregards coo ing, we prefer to provide yertical cooling fins 0 on the exterior of the casing which are much more effective than the radial fins employed on cylindrical surge absorbers owing to the unrestricted path for the air. The cooling of the actual wind- '100 ings when oil is employed may be riormed by the natural convection of the o through suitable oil ducts, and. this agam 1s more eifective in constructions according to the 5 present invention than hitherto racticable.

If oil ducts be not provided, 011 nevertheless im roves cooling by displacing the air from t e spaces between the sheets of insulation (oil having a thermal conductivity many times greater than air).

According to a modification as illustrated in Figure 3 the coil construction is somewhat similar tothat described above except that only two layers of windings are employed in a single plane. The insulation on the conductor may be, however, sufiicient for the insulation between conductor and dissipator v as well as between conductors.

Insulators g, g are at right an Ice to the 90 plane of the coil elements mste of in the same plane as before. The absorber con- 'sists of three pairs of elements connected electrically in series. Between each pair of coils and the adjacent pair a washer of dissipating material 7:. is inserted, washers lo and annular rings m together forming the case and secondary winding of the absorber. The washers k are furnished with vertical cooling fins 0'. The annular rings 'm are welded to the washers h and I: at points 1. Ample provision is therefore given for expansion.

In order to increase the electrostatic capacity of absorbers in accordance with the coated or covered with metal foil or metallized paper. Such conductor covering will improve the heat dissipation of the absorber, and if of suitable material bring the ener conductors.

The formsof construction described above are given by way of example only and may be modified.

For instance, it is not essential that the flat sheets of metal associated with the line the secondary element casing for the purv poses setforth.

2. A lightning or surge absorber as claimed in claim 1 including a core of insulating material disposed at the centre of dissipated into closer association with e the coil in order to reduce the required oil content of the 3. A; lightning or surge A absorber as claimed in claim 1 includ' terminals and external leads disposed at r i g ht angles to the plane of the coil.

4. A lightning or surge absorber as claimedin claim 1 including also vertical cooling fins for said 5. A lightning or 'surge absorber as claimed in claim 1 whereir 'said casing is formed of two circular metal disks spaced a art by an annular ring. of substantially -section.

In testimony whereof I have signed my name to this s ification.

ERIC DOU LAS TOBIAS NORRIS.

present invention the conductor may be

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