US2638120A - Arrangement in protecting relays for liquid-filled electrical apparatus - Google Patents

Description

y 2, 1953 E. STENKVIST ET AL ARRANGEMENT IN PROTECTING RELAYS FOR LIQUID-FILLED ELECTRICAL APPARATUS Filed Aug. 6, 1947 IN VEN TORS: EM/L STE/VK w: r ERIK GunMu/varso/v 14 TIDE/V5) Patented May 12 1953 ARRANGEMENT ,IN PROTECTING RELAYS FOR LIQUID-FILLED ELECTRICAL AP- PARATUS Emil 'Stenkvistand Erik Gudmundsson, Ludvika,

Sweden, assignors to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application August 6, 1947, Serial ,No. "766,706 In Sweden May 5, 1945 Section 1, Public Law 690, August 8,, 1946 1 Patent expires May 5, 1965 2 Claims. 1

In liquid filled electrical apparatus provided with expansion vessels, it is usual to provide a protecting relay in the pipe line between the apparatus and the expansion vessel and, on the development of gas in the apparatus, such relay gives a warning signal and in the event of larger faults releases the apparatus, Protecting relays of this type have been commonly employed in Europe and Canada for several years, see for example Gross, Transformer Protection Electric Engineering of June 1947, pages 564-569. When any defect occurs in the pro tecting relay itself, the movable parts thereof must be removed for repair or inspection and this is ordinarily a simple operation, since all movable parts are usually fastened to a cover or plate on the relay housing, so that the housing itself may remain in the pipe line and it is only necessary to remove the said cover for repair or inspection of the parts. In order to remove the cover from the housing, however, all oil must first be drawn ofi from the expansion vessel, so that the protecting relay will be entirely free from oil. In certain large transformers and other apparatus the quantity of oil in the expansion vessel may amount to several tons, and the operation of drawing off and refilling the oil is therefore very costly. In such cases the protecting relay has been heretofore provided with ordinary stop-cocks, one on each side thereof, and a shunting pipe line has also been provided with a stop-cock therein. The shunting pipe line is necessary for the breathing of the transformer during the time the stop-cocks of the relay are closed and such an arrangement of stop-cocks and shunting pipe lines occupies a very large space and is expensive to make and is, as a rule, not provided as standard but only on special order.

The present invention has for its object to overcome these objections connected with the arrangement above described, and according to this invention special valve means are contained within the relay-housing, such means having dimensions as small as possible and serving to shut off the relay chamber from its inlet and outlet pipe lines, and the relay-housing is provided with a by-pass duct within the relayhousing.

The present invention is more clearly described with reference to the accompanying drawing, which shows a longitudinal section of an arrangement according to the present invention.

In accordance with the present invention the pipe lines 2, 2 lead respectively to a transformer casing and to its expansion vessel (not shown on the drawing). The relay-housing 9 has inserted therein two valve discs H3, which are opened and closed by means of eccentric discs or cams ll fixed on shafts 12, which extend through the Wall of the housing and may be conveniently turned from the outside of the housing. The valve discs H) are movable in a straight line towards or away from the valve seats l3, and the movement of each of the eccentric discs I l is transmitted to its valve disc it] through the medium of a bail i5, which is secured to the valve disc Ill. For this purpose each bail l5 has two guide slots 16 so that the bail I5 together with the valve disc H) is moved towards or away from the valve seat It, when the shaft i2 is turned. In the drawing the valves are shown in dotted lines in their closed position and in full lines in their open position. The dot-anddash lines I? indicate the housing cover l'l supporting in the usual manner the mechanism of the fluid-actuated relay. By the use of an eccentric disc or cam for the operation of each valve, the arrangement requires very little space and the dimensions of the valves need not be increased. In the arrangement shown, the shunting by-pass I4 is contained within the relay-housing 9 and this by-pass is not provided with a stop-cock since the cross-sectional area of this by-pass is so small that the by-pass may remain permanently open without interfering with the function of the relay.

The fluid-operated protecting relay itself may be of any well-known type, and may, for example, comprise a float actuated by the level of the liquid in the housing and a member actuated by the flow through the housing.

We claim as our invention:

1. A device for insertion in a pipe line between a liquid-filled electric apparatus and its expansion vessel, comprising relay means responsive to at least one condition of liquid at the relay means, a housing forming a relay chamber accommodating said means, a detachable cover for said chamber, inlet and outlet ducts in the housing, two valve means, one on the inlet and one on the outlet side of said chamber, and a restricted duct formed within said housing and lay-passing said valve means, each of said valve means including a valve consisting of a valve disc adapted to be moved away from and towards its seat, a slotted bail fixed to said valve disc, cam means located in said bail, and a shaft fixed eccentrically to said cam and extending through the slots of said bail and through one wall of the housing.

2. A protecting device for insertion in a pipe line between a liquid-filled electric apparatus and its expansion vessel, comprising relay means responsive to at least one condition of liquid at the relay means, a housing forming a chamber accommodating said relay means, a detachable plate carried on the housing for giving access to said relay means, fluid ducts formed in the ends of said housing for the passage of fluid through said chamber, valve seats formed around said ducts and aligned with each other, valve discs mounted for movement towards and away from each other to engage and disengage said seats, slotted bails fixed on said valve discs, valve operating cam means located in said bails, actuating shafts fixed to said cam means and extending through the slots in said bails and through one wallof the housing, and a restricted duct formed Within one wall of the housing and permanently by-passing said valve seats.

EMIL STENKVIST. ERIK GUDMUNDSSON.

References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Powell July 5, 1859 Frenier May 24, 1921 Schaefer May 30, 1922 Dean Feb. 12, 1924 Gray Nov. 15, 1927 Patterson Jan. 1, 1929 Ray Feb. 3, 1931 Dowd Sept. 5, 1933 Mullen Apr. 10, 1934 Ingram June 24, 1941 FOREIGN PATENTS Country Date Austria Of 1938

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