US1562428A

US1562428A - Oil-cooled transformer

Info

Publication number: US1562428A
Application number: US422465A
Authority: US
Inventors: Robert V Bingay
Original assignee: PITTSBURGH TRANSFORMER CO
Current assignee: PITTSBURGH TRANSFORMER CO
Priority date: 1920-11-08
Filing date: 1920-11-08
Publication date: 1925-11-17
Anticipated expiration: 1942-11-17

Description

Nov. 17, 192s.V 1,562,428

R. V. BINGAY OIL COOLED TRANSFORMER Filed Nov. 8, 1920 54 Sme/nio@ /af a 55 MJOIZS /7 Patented Nov. 17, 1925.

vmuren ROBERT V. BINGAY, OF PITTSBURGH, PENNSYLVANIA, ASSIGl'NOE' TO PITTSBURGH TRANSFORIVIER COMPANY. A CORPORATIONDF PENNSYLVANIA.

GIL-COOLED TRANSFORMER.

Application led November 8, 1920. Serial No. l122,465i

`To all whom it may concern.'

State of Pennsylvania, have invented cer` tain new and useful Improvements in Oil- Cooled Transformers, of which the following is a specification.

This inventionrelates to transformers and particularly to transformers cooled by a circula-ting liquid `such as oil.l Such transformers are usually placed in a tank pontaining the cooling oilwhich is heated by the transformer and transfers this heat to the outer portion of the tank; The cooling oil is also an insulator and in order to preserve the oil and maintain its insulating properties it has been found desirable to protect it against contact with the outer air.

The object of this invention is to provide a transformer containing means that `will retain the oil out of contact with the surrounding atmosphere and at thesametime.

permit of expansion and/contraction of the oil due toltemperatur'changes.

In the embodiments of the invent-ion shown in the drawings,

Fig. l is an elevational view of a transformer tank and expansion tank in connection therewith,

Fig. 2 is a similar view of a modified form, and

Fig. 3 is a similar diagrammatic -view illustrating a system adapted for a plurality of tanks.

In the embodiment of the invention shown in Fig. l a transformer tank K on a. base B contains the transformer and cooling oil O. The tank K is filled with the oil O up'to the under surface of the cover C to give extended cooling contact and to restrict the area of Contact 'of oil and air, the wholev tank being oil and air tight. To permit ex# pansion of the oil when heated expan' sion tank E is provided for instance standing on thev base B beside the tank K and connected thereto by pipe P having the three-way cock 9 to close the pipe in both directions or open a connection between the tanks E and K or to close thev connection to tank K and open the bottom of tank E to discharge the oil therefrom. The pipe P and tank E are oil and air tight and when the transformer is connected in lcircuit it heats the oil O which expands an amount de endent in general upon the temperature rlse of the oil, compressing the gas or air in the tank E and raising its pressure correspondingly. Upondisconnection ofthe transformer and coolin of the oil the gas pressure in tank E will orcc2 the oil back into tank Kto maintain the latter always full, and it isto be noted that at no time is there any the outer air. I

An overheating of the oil O and resultant excessive rise inv pressure may be taken care of by the safety blowolf W of the tank K or a safety valve V may be provided on tank E to relieve the pressure. The pressure gage S may also be provided in connection with vthe tank E and an oil level gage L and air introducing means A comprising for instance a cylinder D containing a drying agent' suchas calciuml chloride and having a pump or pump connection at its outer end to force in air.

Under normal conditions of operation the apparatus of this invention will retain the transformer oil sealed against escape and against contact with the outer atmosphere so that the liquid cooling system-is hermetically sealed and a circular oat member R may be provided to iioat on the surface of the oil in tank E to further restrict communication with the contact with the air or gas contained in the system. The tank K when cool may be just completely filled for instance to a level l() or an overflow of the oil through pipe P into ltank E may be permitted to establish its own level such as l1 in the tank E or this level may be pumped to any desired point such as l2 and even back up in pipe P by pressur'e through the pump connection A.

If with cool oil the oil pressure at the top of tank K is substantially atmospheric then the gaslpressurc in tank E will be atmos# pheric for level l() of the oil or for

level

11 or 12 it will be thatA ofthe corresponding lUO lcvelin tank K, for instance a few pounds vin' tank' E will be transferred by pipe P to the oil in tank K and when the transformer is in operation the oil O will be under pressure.`

The tank E instead of resting on the transformer base may, where convenient, be mounted in elevated position for instance on top of the transformer cover C as shown 1n Fig. 2 in connection with the tank E', pipe I and cock 20, and its operation here will be substantially similar to that in Fig. l, the gas pressure and its changes being, however, less in this elevated position for a given expansion of the oil so that the pressure variations on the oil in the tank K will be reduced for a given size of expansion tank. These variations would be still further reduced by a higher elevation of the expansion tank and the reduction of the pressure in the expansion tank below atmospheric for instance to a value sufficient to give at- 'mospheric pressure at the top of tank K.

Where there are a numbei of transformers as indicated in diagram in- Fig. 3, the oil supply of all of these transformers may be connected to a single expansion tank preferably placed at an elevated position and acting as a common receptacle for the expansion from all of the transformers. 'This system has the advantage not only of saving a separate tank for each transformer but also of giving a more nearly constant, average pressure in all of the tanks.- The tank E of this system will have its pipes P1, P2', P3, etc., provided with control cocks 31, 32, 33, etc., so that any transformer may be disconnected without affecting the others.

The connection of pipe P to the trans- 'forrner tank K is preferably made at an extreme top point so that a-lr or gas in the tank will be carried over into the expansion tank E and will not remain trapped in the main tank above the level of the pipe opening. Wrhile in the foregoing illustrations of the operation of the expansion system the oil pressure at the top of the transformer tank when coolhas been assumed as substantially atmospheric it may in the tank of this. invention be below atmospheric so'that the subsequent pressure on the hot oil at the top of the tank will be more nearly at'- mospheric. i

In the expansion system of this invention the oil is kept out of contact with the atmosphere so that moisture is excluded and oxygenation of the oil is prevented and the oil is preserved indefinitely. Under normal operation the system requires no attention and after. severe overheating and over pressure it is only necessary with the tank of Fig. l to pump in air or gas to replace that exhausted -by the safety valve. With the expansion tank in raised positionthe air pump A may be replaced by automatic vmeans operating to admit air when the pressure drops below the atmospheric. The expansion apparatus is simple and inexpensive and easily adaptable to differing conditions of transformer installations and while the invention has been described in connection confined thereto but is intended to cover such modifications thereof as fall within the scope of the appended claims.

I claim:

1. In an expansion system for air cooled transformers the combination with a main transformer tank, of a non-expansible tank receiving the overflow from said main tank and having a rigid closed top for trapping andvholding a gas above the surface of said overflow and preventing outside air from havingaccess to the surface of the overflow during the expansion of oil in said main tank. A

2. In an expansion system for air cooled transformers the combination with a plurality of main transformer tanks, of a single non-'expansible tank receiving the overflow from all of said main tanks and having a rigid closed top for trapping and holding a gas above the surface of said overflow and.

preventing outside' air from having access to the surface of the overflow during the' expansion of oil in said main tanks.

3. In an expansion system for transformer tanks the'coinbination with a main tank, of an auxiliary nonexpansible expansion tank connected therewith and adapted to lower the pressure in the main tank to below atmospheric when cool and permit it to rise above atmospheric during the heating of the oil in the main tank. h

4. In an expansion system for air cooled transformers the combination with a main transformer tank, of a non-expansible tank receiving the overflow from said main tank and having a rigid closed top for trapping and holding a gas above the surface of said overflow and preventing outside air from having access to the surface of the overflow during the expansion of oil in said main tank, and means for exhausting gas from said expansion tank when the gas pressure therein exceeds a predetermined amount.

5. In an expansion system for air cooled transformers the combination with a main transformer tank, of a non-expansible tank receiving the overflow from said main tank and having a rigid closed top for trapping and holding a gas above the surface of said overflow and preventing Outside air from having access to the surface of the overflow during the .expansion of oil in said main tank, and means for introducing'air into,

said expansion tank. y

6. In an expansion system for air cooled transformers the combination with a main transformer tank, of a non-expansible tank receiving the overflow from said main tank and having a rigid closed top for trapping and holding a gas above the surface of said overflow and preventing outside air from havingv access to the surface of the overflow during the expansion of oil in said main tank,iand a member oating on the surface of the overfiow in said expansion tank' and lmain tank and preventing the outside air from having access to the surface of the oil, the oil and gas being hermetically sealed against the outside atmosphere during normal operation.

8. In an expansion system for transformers the combination with a maintransformer tank, a rigid non-expansble auxiliary tank connected thereto com letely closed for holding a gas compressedV `y the expansion of oil in the main tank and preventing the outside air from having access to the surface of the'oil, the oiland gas being hermetically sealed against the outside atmosphere during normal operation.

9. In an expansion system for transformers the combination Witha main transformer tank, of an auxiliary tank connected thereto completely closed for holding a gasv compressed by the expansion of oil in the main tank and preventing the outside air from having access to the surface of the oil, the oil and gas being hermetically sealed against the outside atmosphere durlng normal operation, and means permitting v"the escape of gas above a predetermined pressure.

10. In an expansion system for transformers the combination with a' main transformer tank, of an auxiliary tank connected' thereto completely closed for holding a gas compressed by the expansion of oil in the main tank and preventing the outside air from having access to the surface of the oil, the oil and gas being hermetically sealed against the outside atmosphere during normal operation, means permitting the escape of gas above a predetermined pressure, and means permitting the admission of gas..

' ROBERT V. BINGAY.