US2654583A - Air-cooled transformer - Google Patents

Description

Oct. 6, 1953 E. D. TREANOR AIR-COOLED TRANSFORMER Filed Oct. 12, 1949 Inventor-z Edward D.Tr-e an or, by

His Attorney.

Patented Oct. 6, 1953 AIR-COOLED TRAN SFORMEB Edward D. Trcano'r, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application October 12, 1949, Serial No. 121,013 1 Claim. (Cl. 257 191) This invention relates to stationary electrical induction apparatus, and more particularly to a cooling device for such apparatus.

In. the construction of all but the smaller size transformers, it is universal practice to provide some type of cooling system for the transformer in order to conduct away the heat generated by the electrical losses of the transformer.

It is an object of my invention to provide a simple and economical arrangement for air cooling stationary electrical induction apparatus, such as transformers.

It is a further object of my invention to provide a new and improved arrangement for providing forced circulation of air internally and externally of a transformer structure.

In accordance with these objectives, my invention provides a new and improved cooling structure for a transformer in which an electric motor drives two sets of fan blades, one set of blades providing for the internal circulation of air within the transformer, while the other set of fan blades provides the external circulation of air about the transformer structure.

The features of my invention which I believe to be novel are set forth with particularity in the appended claim. My invention itself, however. both as to its organization and use, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawing in which the single figure represents a front elevation, partially cut away, of a transformer equipped with the forced air cooling means .Of my invention.

Referring now to the drawing, there is shown a transformer tank 1 containing a magnetic core I having. winding. legs 3 and 4 which are connected atxthe top and bottom, respectively, by yoke members 5 and 6. Each of the leg membets 3 and .4 is provided with an electrical winding which may consist of a plurality of concerntrio cylindrically-wound coils l, :8, and 9 such as are: illustrated in a partially cutaway view on winding leg .3, These coils maybe connected tother in any desired manner to achieve whatever electrical characteristics are desired. The particular electrical relation existing between the various coils-isnot pertinent to my invention. Cylindricallv-wound coils 1,8, and 9 are separated from each other by suitable axial spacers- (notshown) so as to maintain axial ducts in for a purpose to be hereinafter described. The coils :8 and s on each winding leg are surrounded on their outer periphery by a cylinder H of insulating material.

Conccntrically mounted about the core and winding assembly is a double-walled bafile ii. The outer wall 13 of the baffle is mounted in spaced relation to the wall of the transformer tank I by any suitable means, such as brackets, while the inner wall 14 ofthe baflle is mounted in spaced relation to the surface of insulating cylinders i I, and conforms in shape generally to the outer contours of insulating cylinders H. Thus an air duct is provided between the outer wall 13 of the braille and the inside surface of the transformer tank, and also between the inner wall H of the baifie and the outer surface of insulating cylinders H.

A metal hood I5 surrounds the top of the transformer tank and extends downwardly for the greater part of the height of the transformer tank structure. The hood I5 is spaced away from the exterior of the transformer tank structure to provide a chamber through which air may circulate.

In order to provide both internal and external air circulation in accordance with my invention, there is vertically mounted on top of the hood l'5 an electric motor is having rig-idly attached to its shaft two sets of fan blades I1 and I8, respectively.

As will be seen from the drawing, fan blades H are contained within the chamber formed between the exterior of the tank I and the hood l5, whereas fan blades it are contained within the chamber formed by the inside surface of the tank casing and the outside wall I; of baille II.

It is preferable that the direction of air flow on the outside and inside surfaces of the transformer casing should be in opposite directions in order to provide counter-flow cooling; that is, the direction of air flow in the chamber formed between hood l5 and. the outer surface of tank I should be opposite to the direction of air flow in the chamber formed between the inner surface of tankl and the outer wall 13 of baffle 12. This is shown by the air direction 'fi'ow arrows in the drawing.

Fan blades l1 cause air to be drawn in from the atmosphere and to be force-circulated th o gh e chamber formed between hood l5 and the exterior surface of transformer tank 1. Wh le circula mg hr ugh his chamber, the air passes ver cooling tubes 1-8 through which the nternal air .of the transformer t nk circula es. as will be hereinafter explained. The circulation of the ext rnal .air around the coolin ube l9 and around the exterior surface of tank 1| conducts away heat from the transformer tank, and also from the cooling tubes l9.

Fan blades l8, which are mounted on the same shaft as fan blades ll, cause a circulation of the internal air of the transformer tank partly through the cooling tubes [9 and partly in proximity to the walls of the transformer tank. As will be noted from an inspection of the air flow direction arrows, fan blades [8 cause air from inside the transformer tank to pass partly through the external cooling tubes I9 and partly through the chamber formed between the inside surface of the tank I and the outer wall [3 of baffle l2. This arrangement insures that all air in the transformer tank is either circulated through the cooling tubes [9 which have large heat-dissipation areas, or in close proximity to the walls of the tank which also have large heatdissipation areas. The air after having passed through the cooling tubes I9 or through the chamber between the inner surface of tank I and the outer wall E3 of bailie I2 then passes upwardly through the ducts H3 between the cylindrical windings l, 8 and 9, and also through the duct formed between the exterior surface of insulating cylinder H and the interior wall Id of the baflie I2. The air which passes into the duct between the insulating cylinders I l and the inside wall I l of the bafile l2 passes out through slots 28 in insulating cylinders II and thence through the duct formed between cylindrical coil windings 1 and 8 into the upper part of the transformer tank and back through the fan blades Hi again. It can be seen that ducts Ill and the duct between the exterior of insulating cylinders II and the radially inner surface of wall i l of the bafile l2 are in parallel with each other with respect to the flow of air or other gaseous cooling fiuid through the encasing means or tank I. However, the ducts just mentioned are in series fluid fiow relationship with respect to the duct or chamber formed between the outer wall l3 of the baffle and the inner wall surface of the tank or encasing means I.

Since an air-cooled transformer tank of this type is ordinarily operated at atmospheric pressure, a certain amount of interchange of air occurs between the air of the atmosphere and that inside the tank in order to maintain pressure equilibrium. This interchange for pressure equalization may occur where the fan shaft enters the transformer casing, if a relatively loose seal is used at this point. Alternatively, if, a'tight seal is employed at the point where the fan shaft enters the transformer casing, it obvious that breather means such as are well known in the art could be mounted on the transformer casing to provide for pressure equalization between the interior of the tank and the atmosphere.

In this connection, the internal fan 18 serves the additional purpose of preventing the deposition of dust from the atmosphere on the windings l, 8, 9 of the transformer, thereby aiding in the quicker dissipation of heat from the windings.

Thus, it can be seen that the dual fan system of my invention provides a fan element for circulating air inside of the transformer tank and out through cooling tubes which surround the tank, and another fan element which provides for an external circulation of air around the external surface of the tank and around the external surface of the cooling tubes through which the internal air passes. Through the cooperation of these two fan elements an internal and an external circulation of air is provided, with both fan elements being driven by one motor.

While there has been shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the invention and, therefore, it is aimed in the appended claim to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

A cooling means for an apparatus contained within an encasing means comprising a motor mounted adjacent said encasing means, a shaft turned by said motor, two sets of fan blades displaced axially from one another on said shaft, a hood enclosing said encasing means but spaced therefrom to form a shallow chamber about said encasing means, said hood having openings for the entrance and exit of atmospheric air, one of said sets of fan blades being positioned within said chamber to circulate air in said chamber, said second set of fan blades being positioned interiorly of said encasing means to circulate a gaseous cooling fluid within said encasing means, a double-walled baffle positioned between the interior wall surface of said encasing means and the exterior surface of said apparatus, said baiile having a radially outer axially-extending wall conforming substantially to the shape of the axially-extending inner wall surface of said encasing means and extending for a substantial part of the length thereof but being displaced from said axially-extending inner wall surface sufficiently to provide a shallow first duct for the passage of said gaseous cooling fluid, said baffle having a radially inner wall substantially conforming in shape to the portion of the outer surface of said apparatus which extends axially of said encasing means but displaced from said outer surface of said apparatus sufiiciently to provide a shallow second duct for the passage of said gaseous cooling fluid between the radially inner surface of said inner wall of said bafile and said outer surface of said apparatus, said baffle having a first radially extending wall portion adjacent but displaced from an end of said encasing means, said first radially extending wall portion joining together said radially inner and outer axially-ex tending walls of said bafiie to restrain passage of cooling fluid between said inner and outer Walls of said bafiie, the spaced arrangement of said first radially extending wall portion from the adjacent end of said encasing means permitting fluid flow between said first and second ducts at said end of said encasing means, said baflie having a second radially extending wall portion axially displaced beyond the end of said apparatus and adjacent but displaced from an opposite end of said encasing means, said second radially extending wall portion being attached to said radially outer wall of said baffle and enclosing the area defined by said outer wall, said second set of fan blade being positioned between the axially outer surface of said second radially extending wall portion and the end wall of said encasing means, said second radially extending wall portion being apertured adjacent said second set of fan blades to permit passage of said gaseous cooling fiuid to said second set of fan blades from said second duct, said second set of fan blades providing a circulation of said gaseous cooling fluid in a series path comprising said first and second ducts, and axially extending radiating tubes within said chamber, one end of said radiating tubes connected to said encasing means axially between said second radially extending wall portion and the adjacent end of said encasing means, and the other end of said tubes connected to said encasing means axially between said first radially extending wall portion and the adjacent end of said encasing means, said second set of fan blades providing circulation of said gaseous cooling fluid through said tubes.

EDWARD D. TREANOR.

6 References Cited in the file of this patent UNITED STATES PATENTS Number Number Name Date Randall Jan. 13, 1914 Demers Oct. 13, 1931 Burnham May 2, 1944 Blancha Nov 7, 1944 Melville July 20, 1948 FOREIGN PATENTS Country Date Great Britain Dec. 11, 1930 Great Britain July 18, 1938 Switzerland Sept. 16, 1947

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