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Publication numberUS3894171 A
Publication typeGrant
Publication dateJul 8, 1975
Filing dateNov 20, 1973
Priority dateNov 23, 1972
Also published asDE2358072A1
Publication numberUS 3894171 A, US 3894171A, US-A-3894171, US3894171 A, US3894171A
InventorsKusay Roland Gregor Paul
Original AssigneeBritish Oxygen Co Ltd
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrical transformers
US 3894171 A
Abstract
The cooling oil in large electrical transformers is purified, by having sorbed water and gases removed, by means of a vacuum treatment vessel permanently plumbed to the transformer. The desorbing treatment is carried out while the transformer is live, so that the oil needs little or no extra heat supplied before it can be treated.
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Description  (OCR text may contain errors)

United States Patent [191 Kusay July 8, 1975 [54] ELECTRICAL TRANSFORMERS 3,675,395 7/1972 Baranowski 55/164 [75] Inventor: Roland Gregor Paul Kusay,

Blechingley, England Primary ExaminerSamih N. Zaharna [73] Ass1gnee: TheBntrsh Oxygen Compan Assistant ExaminerRichard W. Burks Lmmed London England Attorney, Agent, or FirmDennison, Dennison, 22 Filed: Nov. 20, 1973 Townshend & Meserole [21 Appl. No.: 417,559

[ 30] Foreign Application Priority Data [57] ABSTRACT Nov. 23, 1972 United Kingdom 54199/72 [52] Us Cl 174/14 R; 55/164. 55/190. The cooling oil in large electrical transformers is puri- 210/223; fied, by having sorbed water and gases removed, by [51] Int CL. Holb 9/06;BO1d 19/OO-.BO1d 39/00 means of a vacuum treatment vessel permanently [58] Field of Search u 55 /21 52 5 5 164 plumbed to the transformer. The desorbing treatment 55/189 190 210/222 174/121 R 15 is carried out while the transformer is live, so that the oil needs little or no extra heat supplied before it can [56] References Cited be treated- UNITED STATES PATENTS 2,340,898 2/1944 Race 55/189 X 2 Claims, 1 Drawing Figure tim ELECTRICAL TRANSFORMERS This invention relates to big electrical transformers of which the windings are immersed in a dielectric oil housed in a container.

The dielectric strength of such an oil is appreciably reduced by the presence in it of water, gas or particulate impurities. This leads to inefficient operation of the transformer as its losses increase with time as the oil becomes increasingly adulterated as water and gas from the atmosphere are absorbed by the oil. While solid impurities can be removed by filters having pores of appropriate size, absorbed gases and water vapour have to be removed by a desorption process.

It is known to treat electrical oils intermittently by coupling up the transformer container at chosen intervals to a mobile treatment unit employing filters, electrical or other heaters, and vacuum degassing apparatus. The treatment unit consumes a lot of power in heating the oil up to its treatment temperature, and takesa long time because of the care which has to be taken during the heating process to limit the temperature which the oil reaches so as to avoid thermally decomposing the oil. Immediately prior to the treatment, and during all the time that the treatment is taking place, the transformer is out of commission, and hence elaborate and expensive measures have to be taken to make up for this.

The present invention aims at enabling transformer oil to be treated while the transformer is live, but obviating, or at least reducing, down-time of the transformer.

Accordingly the present invention provides an oilinsulated electrical transformer which is as claimed in the appended claims.

The present invention willl now be described by way of example with reference to the accompanying drawing, which is a diagrammatic view of a transformer of the present invention.

A transformer casing 2 houses the windings and insulating oil of the transformer, electrical connection to the transformer windings being effected by means of insulating bushings 4.

Extending from the lower part of casing 2 is a conduit 6 leading through a valve 8 to a filter vessel 10 which 'is designed to remove from the oil at least a high proportion, if not all, of any solid particles in suspension in, or entrained by, the oil stream. The filtered oil stream passes along conduit 6 and through a flowcontrol valve 12 to the upper partof a vacuum treatment vessel 14, having a central compartment 16 in which are packed Raschig rings or other column fillers 17 over which the oil to be treated flows in a thin film. In so doing, the oil is subjected to vacuum by means of a vacuum pump 18 driven by an electric motor 20. P0- sitioned in the lower part of vessel 14 is a level-sensing switch 22.

The conduit 6 leading from the bottom of vessel 14 passes through an oil pump 24 and a permanent magnet filter 26 to a discharge valve 28. From valve 28 the treated oil passes through a valve 30 before reentering the interior of casing 2.

Associated with the apparatus is a control unit 32 which is connected to valve 8; motor a vacuum gauge 21; level-sensing switch 22, and pump 24.

By means which do not form part of the subjectmatter of the present application, and which are therefore not described in further detail, the control unit 32 acts to open valve 8 when the level of contamination of the oil in chamber 2 reaches a chosen value. It is also effective to monitor the degree of vacuum in vessel 14 and to start the vacuum pump when the pressure in the interior of vessel 14 rises to too high a value. It is also effective to switch the vacuum pump off when the pressure in vessel 14 has fallen to a chosen minimum level.

Control unit 32 is also effective to energise pump 24 when the level-sensing switch 22 indicates that there is sufficient volume of vacuum-treated and filtered oil in the bottom of the vessel 14.

The discharge valve 28 can be operated either automatically or manually as need arises.

For the treatment process to be successful, it is necessary for the temperature of the contaminated oil to be treated to be raised to about 4565C. At this temperature the surface tension of the oil is sufficiently low to allow any absorbed gases or vapours to be desorbed by the application of a suitable degree of vacuum in vessel 14. In accordance with the present invention, the oil is raised to this treatment temperature by the waste heat normally released by the transformer windings when it is operating. If the oil does not normally reach the desired treatment temperature, or if it falls below this temperature under adverse weather conditions, it is within the purview of the present invention to incorporate an auxiliary heater 34 in conduit 6 before filter 10.

In view of the relatively large mass of oil required to be treated, the heater will be of insufficient capacity to heat all the oil in casing 2 from ambient temperature to the treatment temperature, so that the major proportion of the heat necessary would be supplied by the transformer windings. This leads to a substantial reduction in the expense of the degassing equipment, in that the heater can be of very low rating compared with that necessary for existing mobile servicing units.

The degree of contamination of the oil can be monitored either continuously or intermittently, and the results of the monitoring can be used to cause control unit 32 to switch on the treatment unit when the degree of contamination has risen to a specified level. However, it might be desirable in some circumstances to keep the treatment unit operating continuously so that any contaminants are removed more or less immediately after they appear in the oil.

The choice between these two conditions is made on considerations which do not effect the mode of operation of the present invention, and so will not be described further.

I claim:

1. An oil insulated electrical transformer including a casing having an outlet permanently communicating its interior with vacuum degassing apparatus for treatment of the oil while the transformer is live, means for feeding oil to the degassing apparatus, and returning treated oil to the interior of the casing, either continually or intermittently, the degassing apparatus including a compartment containing packed column fillers over which the oil can flow in thin films, said compartment being connected to a vacuum pump, a control unit operatively connected between the compartment and vacuum pump to turn the vacuum pump on when the pressure in the compartment is above a chosen maximum; and to turn the pump off when the pressure is below a chosen minimum, a valve located at the outlet of the casing and controlling flow of oil from the interior of the casing, said control unit opening the valve when the contamination in the oil in the casing reaches a chosen level, and a second valve located at the inlet of the casing and controlling the flow of treated oil toward the interior of the casing.

2. A transformer as claimed in claim 1, in which a filter vessel is located between the outlet of the casing a permanent magnet filter being located between the outlet of the oil pump and the inlet of the casing.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2340898 *Nov 29, 1941Feb 8, 1944Gen ElectricElectric apparatus
US3675395 *Oct 9, 1970Jul 11, 1972Keene CorpApparatus for the purification of oils and the like
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4234754 *Feb 23, 1979Nov 18, 1980Bicc LimitedOil-filled electric cable installations comprising pressurizing oil tanks
US4280014 *Feb 14, 1980Jul 21, 1981Bicc LimitedElectric cable installations
US4358379 *Nov 21, 1980Nov 9, 1982Noboru InoueProcess for refining electric insulating liquids
US4526677 *Jun 4, 1984Jul 2, 1985Rockwell International CorporationRemoval of polyhalogenated biphenyls from organic liquids
US5976226 *Dec 18, 1997Nov 2, 1999Bastian; JuergenMeans to ensure a minimum of gas content in liquids used for heat exchange and insulating purposes with complementary means for liquid expansion into vessels with variable volumes
US6217634 *Aug 27, 1999Apr 17, 2001Electric Power Research Institute, Inc.Apparatus and method for monitoring and purifying dielectric fluids
US6391096Jun 9, 2000May 21, 2002Serveron CorporationApparatus and method for extracting and analyzing gas
US6491742Aug 3, 1999Dec 10, 2002Tokyo Electron LimitedESRF coolant degassing process
US7409849 *Nov 22, 2004Aug 12, 2008Filmax, Inc.Oil filtration system for plural phase power equipment tanks
US20080295904 *Jul 31, 2008Dec 4, 2008Filmax, Inc.Oil filtration system for plural phase power equipment tanks
CN103594227A *Oct 24, 2013Feb 19, 2014国家电网公司Transformer high-voltage side incoming cable oil tank three-phase assembly
CN105140014A *Sep 24, 2015Dec 9, 2015江苏宏源电气有限责任公司Method for oil injection of liquid immersed type distribution transformer
CN105185519A *Jul 29, 2015Dec 23, 2015国网山东省电力公司电力科学研究院Online monitoring and purifying system for transformer oil
CN105185519B *Jul 29, 2015Jun 29, 2016国网山东省电力公司电力科学研究院一种变压器油在线监控净化系统
CN105223277A *Nov 20, 2015Jan 6, 2016江苏有能电力自动化有限公司Novel transformer oil chromatography online monitoring device
CN105223277B *Nov 20, 2015Jul 18, 2017江苏有能电力自动化有限公司一种新型变压器油色谱在线监测装置
CN105223297A *Nov 20, 2015Jan 6, 2016江苏有能电力自动化有限公司Novel special degassing device for oil chromatography online monitoring device of transformer
CN105223297B *Nov 20, 2015Jul 18, 2017江苏有能电力自动化有限公司一种新型变压器油色谱在线监测装置专用的脱气装置
CN105259260A *Nov 20, 2015Jan 20, 2016江苏有能电力自动化有限公司Novel transformer oil chromatography online monitoring device with three-way valve
WO2000007688A1 *Aug 3, 1999Feb 17, 2000Tokyo Electron LimitedEsrf coolant degassing process
WO2015141612A1 *Mar 16, 2015Sep 24, 2015国立大学法人東京大学Separation apparatus, fluid device, separation method, and mixing method
Classifications
U.S. Classification174/14.00R, 210/223, 96/169, 96/201, 208/262.5
International ClassificationH01F27/14, H01F27/10, B01D19/00
Cooperative ClassificationB01D19/0063, H01F27/14
European ClassificationB01D19/00R, H01F27/14
Legal Events
DateCodeEventDescription
Apr 5, 1991ASAssignment
Owner name: COLOROLL (MARCH 1990) LIMITED
Free format text: CHANGE OF NAME;ASSIGNOR:POROUS ELEMENT HEATING LIMITED;REEL/FRAME:005668/0126
Effective date: 19900820
Owner name: POROUS ELEMENT TECHNOLOGY LIMITED, BROOKHILL ROAD,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COLOROLL (MARCH 1990) LIMITED;REEL/FRAME:005668/0128
Effective date: 19910307
Apr 5, 1991AS02Assignment of assignor's interest
Owner name: COLOROLL (MARCH 1990) LIMITED
Owner name: POROUS ELEMENT TECHNOLOGY LIMITED, BROOKHILL ROAD,
Effective date: 19910307
Apr 5, 1991AS01Change of name
Owner name: COLOROLL (MARCH 1990) LIMITED
Owner name: POROUS ELEMENT HEATING LIMITED
Effective date: 19900820
Apr 16, 1981ASAssignment
Owner name: POROUS ELEMENT HEATING LIMITED, HAVENSIDE, BOSTON,
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BOC INTERNATIONAL LIMITED;REEL/FRAME:003847/0172
Effective date: 19810330
Apr 16, 1981AS02Assignment of assignor's interest
Owner name: BOC INTERNATIONAL LIMITED
Owner name: POROUS ELEMENT HEATING LIMITED, HAVENSIDE, BOSTON,
Effective date: 19810330