US2447883A

US2447883A - Electrical induction apparatus

Info

Publication number: US2447883A
Application number: US528716A
Authority: US
Inventors: Lawrence C Whitman
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1944-03-30
Filing date: 1944-03-30
Publication date: 1948-08-24
Anticipated expiration: 1965-08-24

Description

Aug. 24,

L. c. WHITMAN 2,447,883 mcrkrcu xunucnon Arrnnus Filed larch 30, 194.4

In'ventor': Lawrence C. Whitman,

His Attorney- Patented Aug. 24, 1948 2,447,883 ELECTRICAL INDUCTION APPARATUS Lawrence C. Whitman, Pittsiield, Mass assignor to General Electric Company, a corporation of New York Application March so, 1944, Serial No. 528,716

1 9 Claims.

My invention relates to electrical induction ap- Daratus such as transformers and reactors and to the type in which the 'core and coils are immersed in an insulating and cooling dielectric liquid.

In the manufacture of electrical induction apparatus, such as transformers which'have a liquid filled casing, it is customary to employ a gas chamber or conservator on the top of the transformer casing which communicates with the inside of the transformer casing. In some applications, however, where the height of the apparatus should be kept to a minimum it has been suggested to place the gas expansion chamber other than on top of the casing, such as on the side thereof. Such liquid filled apparatus has also been cooled by the use of .cooling radiators which are connected to the top and bottom of the casing so that the dielectric fluid may circulate by free convection up through the core and coils and down through the radiator.

It is therefore an object of my invention to provide a liquid filled electric induction apparatus with an improved expansion chamber construction.

A further object of my invention is to provide an electric induction apparatus of the liquid filled type which has a minimum height and floor space.

A further object of my invention is to reduce the quantity of liquid necessary for filling the casing of a liquid filled electric induction apparatus.

A still further object of my invention is to provide an improved arrangement for cooling an electric induction apparatus.

Further objects and advantages of my invention will become apparent from the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

In the drawing, Fig. 1 is a side elevationin partial section of a transformer which is provided with an embodiment of my invention; Fig. 2 is an end view in section of the transformer illustrated in Fig. 1.

In the construction illustrated in the drawing I have shown my invention as applied to an electrical induction apparatus, such as a transformer, but it will be understood that my invention may be employed with any other suitable type of electrical apparatus which is liquid filled. The construction as shown in the drawing includes any suitable type of core [0 with cells H surrounding the core winding leg. Enclosing the core and coils is a casing II. A cover I: is pr0- vided so that the casing and cover provide a substantially fluid tight enclosing casing. Suitable bushings H are placed in the casing side walls for lead-in conductors which connect to the coils i I. It will be understood that any suitable bushing may be employed which is substantially fluid tight and has a tight seal with the casing. In order to provide a cooling and dielectric liquid for the core and coils the casing contains any suitable liquid such as oil or a chlorinated hydrocarbon of the type described in Patent 1,931,373 to Clark, issued October 17, 1933, and assigned to the same assignee as this present invention.

In' order to provide a suitable expansion chamber for absorbing the pressure changes due to expansion of the liquid during increases in temperature, I provide an expansion chamber it which is inside the-casing 82, such as being near the top thereof. The expansion chamber includes partitions ii and I! and a bottom 18, the partitions II and H being attached to the lower surface of the cover I 3 in any suitablemanner such as by welding to provide a substantially fluid tight joint. The expansion chamber H5 may be filled with a suitable gas such as nitrogen. Communication is provided between the gas expansion chamber and the inside of the casing by an opening 19 in the side wall ll of the gas expansion chamber.

In order to allow for a suitable expansion of the liquid, the liquid is filled to a level which at no load will be below the top of the transformer casing and preferably in the vicinity of the bottom 18 of the gas expansion chamber such as at a level indicated by the line 20. Furthermore,

the side walls 96 and I! of the gas expansion chamber are spaced from side walls 2| and 22 respectively of the casing a predetermined amount which depends upon the size of the casing and the amount of liquid employed so.

that upon heating of the liquid, the liquid will rise into the space between the side walls of the gas expansion chamber and the casing. Thus,

Y when the liquid is heated due to any predetermined load on the transformer, such for example full load, the oil may rise in the space between the side walls am; suitable amount such as that indicated by the dash line 24. In order to maintain the liquid at suitable limits of temperature and pressure, when a predetermined load is reached such as full load, I provide cooler means which may be of any suitable type and which, in the construction illustrated in the drawing, includes a plurality of tubes 25 which are connected at the bottom through a header 2| and at the top through a header 21. It will be noted that the header 2! communicates with the side wall of the casing at approximately the level of the liquid indicated for full load and thus when the level reaches the header 2'' the oil may circulate by free convection up through load or full load condition, a tube 213 is provided which has one end in the opening it) and the second end 29 adjacent the lower portion or bottom i! of the gas expansion chamber. Thus the oil upon being sumciently heated may. expand into the tube and from there into the gas expansion chamber. It will also be seen that upon cooling of the oil such as will happen when the load is removed, the oil will begin to contract and due to the siphon tube 28 the oil will not be left in the bottom of the gas expansion chamber but due to the pressure built up by displacing the gas in the gas expansion chamber, the compressed gas will force any oil above the bottom 29 through the tube and into the main casing. It will be understood, of course, that there may be a very small volume of liquid left in the bottom of the gas expansion chamber in the space between the bottom of. the siphon tube 28 and the bottom it of the gas expansion chamber. However, this may be made a minimum amount within the usual manufacturing tolerances.

It will be seen from the above that I have provided a casing and gas expansion chamber construction for an electric apparatus such as a transi'ormer which has a minimum of height and weight, since the expansion chamber is placed inside the tank which will also use a minimum of liquid since the volume of the gas expansion chamber will displace the amount of liquid which overwlse would be used were the expansion chamber placed outside the tank. In order that the liquid may expand in the space between the side walls of the gas expansion chamber and the casing, the proportions of the sides of the casing and gas expansion chamber may be made any suitable value. Thus for example in the drawing, if the total height of the transformer is about 56 inches,

the gas expansion chamber may be about inches high and with a space about 1 inch between the side walls of the gas expansion chambet and the adjacent side walls of the casing. Thus with the oil having a level at noload or at degrees C. approximately in line with the bottom id of the gas expansion chamber, upon full load the oil will reach a level at about 2 inches below the top of the casing, and by providing the header 2'! of the cooler tube at slightly below this level the liquid will circulate through the cooler tube upon reaching approximately full load. Furthermore, the opening it may be placed any suitable place, such as slightly above the full load level or for a transformer having the dimensions as given above of approximately between an inch and a half inch from the top of the casing.

For protecting the apparatus against sudden internal pressure increases which might result from a. short circuit or heavy overload I provide a rupturable diaphragm supported in an opening in the bottom wall it of the gas expansion chamber, as illustrated in Fig. 2. The diaphragm may be supported relatively tightly over the opening in any suitable 'manner such as by the use of a collar 3 I Any suitable means may be employed menses for rupturing th diaphragm upon the attainment of a predetermined pressure in the transformer casing, such as by a. diaphragm rupturing arrangement 32 which is described in further detail in Patent 2,337,361 to Vienneau, issued December 31, 1943, and assigned to the same assignee as this present invention. By providing the rupturable diaphragm in the wall of the expansion chamber instead of in the outer wall of th transformer casing, high pressures due to a fault in the transformer which are not equalized through the relatively small tube 28 may be quickly released into the chamber it without exposing the insulating outside air. Also any small quantities of smoke or fumes released by the liquid due to the fault,

will not contaminate the outside air, which may be an important consideration when the transformer is installed in an enclosed room. such as in a basement.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to the particular embodiments described. and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

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

1. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing and in the vicinity of the top of said casing, said partition means providing side walls of said chamber spaced from the side walls of said casing, a dielectric liquid within said casing and having a no load level below the top of said casing so that upon heating 'said liquid may expand into the space between the side walls of said chamber and said casing, gas in said chamber, means providing an opening between said casing and chamber in the vicinity of the full load level of said liquid, and means for returning said liquid from said chamber to said casing when the liquid level in the casing falls below said full load level after rising above it.

2. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing and in the vicinity of the top of said casing, said partition means providing side walls of said chamber spaced from the side walls of said casing. a dielectric liquid within said casing and having a no load level below the top of said casing so that upon heating said liquid may expand into the space between the side walls of said chamber and said casing, gas in said chamben-and tube means having an end in an opening in a side wall of said chamber in the vicinity of the full load level of said liquid and another end within said chamber near the bottom thereof.

3. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing and in the vicinity of the top of said casing, said partition means pro- Viding side walls of said chamber spaced from the side walls of said casing, an opening in the side walls of said chamber near the top thereof, a dielectric liquid within said casing and having a no load level near the bottom of said chamber so that upon heating said liquid may expand into the space between the side walls of said chamber and said casing, gas in said chamber, cooler means having connection with said casing near the bottom thereof and near the top thereof below the level of said liquid at a predetermined load so I Q I A V that liquid may circulate in said casing and cooler upon said apparatus reaching said predetermined load.

4. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing, a dielectric liquid in said casing having a no load level near the bottom of said chamber, said partition means providing a side wall of said chamber spaced from a side wall of said casing a predetermined amount in relation to the amount of liquid and size of the casing so that upon heating said liquid will expand into the space between said spaced side walls of said chamber and casing to a predetermined level upon said apparatus reaching a predetermined load, an opening in th side wall of said chamber near the top thereof, and cooler means connected to said casing in the vicinity of said predetermined level of said liquid so that said liquid may flow into said cooler and be cooled.

5. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing, a dielectric liquid in said casing having a no load level below the top of said casing, said partition means providing a side wall of said chamber spaced from a side wall of said casing a predetermined amount in relation to the amount of liquid and size of the casing so that upon heating said liquid will expand into the space between said spaced side walls of said chamber and casing to a predetermined level upon said apparatus reaching a predetermined load, and a tube in an opening in said side wall of said chamber in the vicinity of said predetermined load and another end near the bottom of said chamber.

6. An electric induction apparatus including an enclosing casing, partition means providing a chamber within said casing, a dielectric liquid in said casing having a no load level below the top of said casing, said partition means providing a side wall of said chamber spaced from a side wall of said casing a predetermined amount in relation to th amount of liquid and size of the casing so that upon heating said liquid will expand into the space between said spaced side walls of said chamber and casing to a predetermined level upon said apparatus reaching a predetermined load, cooler means connected to said casing in the vicinity of said predetermined level of said liquid so that said liquid may flow into said cooler and be cooled, and a tube in an opening in said side wall of said chamber above said predetermined level with an end inside said chamber near the bottom thereof.

7. In combination, an nclosing casing for electric apparatus, a hollow chamber attached to the inner side of the cover of said casing and extending down into said casing, a liquid filling said casing to substantially the level of the bottom of said chamber when said apparatus is unloaded, an opening in said chamber near the top thereof, a gas filling said chamber and the space in said casing above the level of said liquid, and an external radiator connected to said casing near the bottom thereof and near the top thereof below the level of said opening in said chamber, the volume between the walls of said casing and chamber being such that the full load heating of said apparatus expands said liquid until it rises between said walls to a level which is between said opening in said chamber and the upper connection of said radiator to said casing.

8; In combination, an enclosing casing for electrical apparatus, a hollow chamber attached to the inner side of the cover of said casing, and extending down into said casing with an annular space between the walls of said chamber and casing,-a liquid filling said casing to substantially the level of the bottom of said chamber when said apparatus is unloaded, an opening in said chamber,near the top thereof, a gas filling said chamber and the space in said casing above the level of said liquid, an external radiator connected to said casing near the bottom thereof and near the top thereof below the opening in said chamber, the volume between the walls of said casing and chamber being such that full load heating of said apparatus expands said liquid until it rises between said walls to a level which is between said opening in said chamber and the upper connection of said radiator to said casing, and a pipe connected to said opening in said chamber and extending downwardly into said chamber substantially to the bottom thereof whereby any of said liquid which is forced into said chamber as a result of overloading of said apparatus will be returned to said casing through said pipe by the pressure of the gas in said chamber during subsequent cooling of said liquid.

9. In combination, an enclosing casing for electrical apparatus, a hollow chamber attached to I the inner side of the cover of said casing and extending down into said casing with an annular space between the walls of said chamber and casing, a liquid filling said casing to substantially the level of the bottom of said chamber when said apparatus is unloaded, an opening in said chamber near the top thereof, a gas filling said chamber and the space in said casing above the level of said liquid, an external radiator connected to said casing near the bottom thereof and .near the top thereof below the opening in said chamber, the volume between the walls of said casing and chamber being such that full load heating of said apparatus expands said liquid until it rises between said walls to a level which is between said opening in said chamber and the upper conassurances crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,232,834 Nichols July 10, 191! 1,721,331 Bugatti July 18, 1929 2,337,361 Vienneau Dec. 21, 1943 FOREIGN PATENTS Number I Country Date 158,698 Germany Feb. 25, 1905 527,486

Germany June 18, 1931