US1967653A

US1967653A - Bushing insulator

Info

Publication number: US1967653A
Application number: US520286A
Authority: US
Inventors: Arthur O Austin
Original assignee: Ohio Brass Co
Current assignee: Ohio Brass Co
Priority date: 1931-03-05
Filing date: 1931-03-05
Publication date: 1934-07-24
Anticipated expiration: 1951-07-24

Description

July 24, 1934. A. o. AUSTIN BUSHING INSULATOR 3 Sheets-Sheet 1 Filed March 5, 1931 .mll

E E Il: mr nu E 1N VENTQR Arf/wr 0. Ausf/f7. el Q Eg y //M A TTORNE Y July 24, 1934. A. o. AUSTIN BUSHING INSULATOR Filed March 5, 1931 3 Sheets-Sheet 2 3 f /1/ f, f

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July 24, 1934. A Q AUSTIN 1,967,653

BUSHING INSULATOR Filed Maron 5, 1951 s sheetS-sheet s [1V l/ENTOR v CT A TTORNEY Patented July SM, i234 i i y i.

USG MS'UMTH,

Jersey Application March 5, 1931i, Serial No. .52@,266 Y 23 Claims.

This invention relates to bushing insulators and has for one of its objects theprovision of means for discharging the filling fluid from the interior of the bushing insulator without the necessity of reaching the lower end of the insulator.

A further object of the invention is to provide means for maintaining the insulator at a constant temperature.

Other objects and advantages will appear from the following description.

The invention is exempliiied by the combina'- tion and arrangement of parts shown in the accompanying drawings `and described in the following specification, and it is more particularly pointed out in the appended claims. i

In the drawings:

Fig. 1 is an elevation with parts in section showing one form of the present invention.

Fig. 2 is a part section and part elevation of the upper end of an insulator having a modied form of the invention applied thereto.

Fig. 3 is a part section and part elevation of the lower end of the insulator corresponding to Fig. 2.

Fig. 4 is a view similar to Fig. l showing a different form of the invention.

Fig. 5 is a view similar to Fig. 1 showing still another form of the invention.

1n high voltage bushings, particularly those filled with oil or other fluid insulating medium, it sometimes becomes advisable to change the fluid when its dielectric strength is reduced by absorption oi water or conducting compounds caused by electrostatic discharges. This is particularly true where the insulating batlies or cylinders in a bushing are made of material which will take up moisture or which will carbonize due to leakage or charging current.

It has been common practice to provide lling or emptying means at the iange of the bushing. Since, however, the oil of lowest dielectric strength will be found at the bottom of the bushing, it is evident that filling from the flange will not re move the material of lowest dielectric strength.

llt is also diflicult to change the oil where it is necessary to get at the lower end of the bushing, as where the bushing extends into a closed housing. This will necessitate taking the bushing out of service and possibly lowering the oil level in the housing to get at the lower end connection. Where bushings are placed in a transformer housing, this is a serious matter and constitutes an increased hazard.

The present invention provides means for changing the oil in a bushing, which may be operated without reaching the inner or enclosed end of the bushing, and which will permit change of the insulating medium without taking the bushing out of service. The same means for changing the medium may also be used for obtaining a (Cl. NES-Jell) sample-of the filling medium to see whether ci not a change is necessary or advisable.

1n the form of the invention shown in Fig. 1 the

members

10 and 11 form the outside case or insulating members of 'the bushing which en- 65 close insulating baffle 12. The bushing is provided with a hollow conductor member 13 having a valve seat 14 pierced by an orifice l5.v The orifice 15 is closed by a needle valve or other suitable closing device 16.' An opening 17 is pro- 70 vided in the wall of the conductor 13 and in the side of the block forming the valve seat 14.

When it is desired to change the oil in the bushing it is not necessary to go below the metal supporting iiange 18, as the weather cap 19 may 75 be removed, exposing the rod 20 which is attached to or a part of the needle valve 16. The valve 16 may then be opened by rotating the rod 20 by means of a wrench or other suitable instrument applied to the head 21 of the rod 80 20. This will permit the oil to be discharged through the opening l5. The oil may be replen ished through the lling plug 22 at the ange, or through the filling plug 23 inthe expansion reservoir. if desired, the bushing may be entire- 35 ly emptied and refilled, or the oil changed, without lowering the level so as to avoid possible air traps.

The same general principle applied in a differn ent form is shown in Figs. 2 and 3.. 1n this form 96 acentral pull rod 24 is used for attaching the lower terminal 25 with its conductor lead 26, so that a bushing may be removed or installed in a transformer housing or other apparatus without the necessity of lowering the oil level or Q5 reaching the lower end of the bushing to attach vthe vterminal lead 26.

through the center of the bushing as the bushing i is lowered into place. After the bushing is in place, the pull rod 24 is tightened or placed under tension, which insures good contact between the contact member 28 at the lower end of the bushing and the terminal 25. By placing the gasket 27 between the removable terminal member 25 attached to the lead 26 and terminal 28 attached to the bushing, it is possible to effect a tight seal at this point. By providing an openn ing 29 in the hollow conducting member 30, ll() oil may be discharged from the space inside the bushing to the space between the pull rod 24 and the Wall of the conducting tube 30. By loosening the pull rod 2li which will permit terminal cap 25 to drop to bring the openings 3l in reg- 115 istration with the groove 32, the oil may be discharged througli' openings 31 or suitable grooves permitting the bushing to be drained. The arrangement at the upper end of the bushing permitting lowering ci the pull rod 24 is shown in 12 `lfig. 2. @e rod 24 is provided with nuts 33 for tightening the rod and holding it in place. These are readily accessible by removing the weather cap 34. The nuts 33 rest upon washers 54 supported on the upper end of the conductor tube 30. The tube is'held under` tension by springs 35 resting on the bottom of the reser- Voir 36.

Instead of draining the oil by opening the valve 16, the arrangement shown in Figs. 2 and 3 makes it possible to remove the oil from the bottom of the bushing through the upper end.

The cap 37 is provided with a plugged opening 38 and the terminal 3dr has an opening register ing with the opening 38. When it is desired to remove the oil from the bushing, the plug is removed from the opening 38 and a connecting pipe inserted in its place. By applying suction to the connected pipe by any suitable means such as siphoning, oil' will be drawn up through the space between the draw rod 24 and the wall of the conducting tube 30. The washers 54 are provided with suitable grooves to permit upward iiow of the oil. The oil will be drawn from the lower end of the bushing through the opening 29. With this arrangement it is not necessary to provide an opening at the lower end of the bushing so the danger of leaks can be avoided.

If desired, the bushing may be entirely drained before refilling or a fresh supply of oil allowed to enter at an opening in the filling iiange, as shown in Fig. 1. A preferable method, however, is to remove the filling plug 39 in the reservoir 36 and allow the new oil to ow in through this opening as the old is withdrawn through-opening 38 so as to maintain the oil level. If the new oil is warmer than the oil being removed, there will be but very little mixture of the two and a complete change of the oil may be elected in exceedingly short time.

In the form of the invention shown in Fig. li, the inner baffle 39 forms a tube through the bushing for the' removal of the oil. The upper end of the baille 39 is closed by cork or other suitable packing material 40 through which an outlet tube 41 extends. The outer end of the tube 4l may be closed by a cap 42. The lower end of the baiile 39 may be left open or provided with an extension 43 having its lower end open inside the outer shell at its bottom end. With the construction shown in Fig. 4, all that is necessary to replace the oil in the bushing is to remove the cap 42, attach suitable connecting means and apply the necessary suction to draw the oil through the

tubular members

39, 4l and 43. This may be accomplished by any suitable means such as a -siphon or suction pump. A fresh supply of oil may be admitted through suitable openings or passages 44 in the upper terminal or through the hole in the supporting ange if desired.

Another form of the invention which may have a material advantage in some types where a central passage is not easily provided is shown in Fig. 5 in which an insulating tube 46 extends to the bottom of the bushing and is connected at its upper end to a suitable outlet 47 at the ange. This member 46 may be a'ber, porcelain, glass, or insulating tube made of suitable material. In order to change the oil in the bushing, all that is necessary is to open the member 47 and allow the oil to discharge. A threeway valve 48 is provided for this purpose. If oil is filled in through the upper filling plug 49, the oil may be readily changed in the bushing inattesa even without taking the bushing out of service. Where the member 46 Within the insulator is formed of dielectric material, the connecting conduit outside of the insulator may be of conducting material. Where cil and Water are placed under high stress in a bushing, Water is sometimes precipitated. This tends to accumulate in the lower end of the bushing. 1t is therefore advantageous to be able to withdraw the liquid from the lower end of the bushing. The ability to maintain a definite 'standard in the insulating oil has the advantage that the electrical characteristics of the bushing will not change materially. This is important where a capacitance coupling is to be used and a high degree of accuracy maintained. The capacitance coupling shown in Fig. 5 is similar to that of my prior Patent #1,910,228, dated May 23, 1933. The baffle 55 has a metallized surface 56 forming an electrostatic coupling with the central conductor 57. A lead 58 extends out through the bushing 59 and is connected with the primair C a transformer 60. The other terminal transformer primary is grounded at 61. Charging current for the capacitance member 56 passes through the transformer primary. The secondary of the transformer is connected to any electrical translating device to be energized such as a meter, relay or synchronizing apparatus.

The invention also has the advantage that means may be provided for maintaining a constant temperature in the bushing. In order to maintain a constant temperature in the bushing, connection 50 is provided between the outlet 47 and an inlet 51. If the outlet 47 and inlet 5l are connected to a suitable oil supply which may be circulated and in which the temperature may be controlled, it is evident that the temperaturc within the bushing may be controlled to practically any desired point. This may be readily effected by connecting the outlet 47 and inlet 51 by a tubular member 50 in such a Way that the oil may be warmed by a heating element 52, heat being supplied by an electric current controlled by a suitable thermal relay 53. By heating the oil it is possible to produce sufficient heat so as to force the circulation and thereby maintain the temperaturein the bushing. This temperature may be controlled either through limiting the maximum amount by the relation of radiation to heat supplied, or by the use of the relay which may be placed in the circulating oil supply of the bushing at the bushing or elsewhere if desired.

By raising the temperature of the bushing above the air, the insulating property of the bushing will be maintained and the danger of flashover particularly under fog and dirt conditions will be greatly reduced. A system of this kind may be used which may tend to heat up the bushings through any suitable relay which may be actuated by humidity or temperature, or through periods when it is desired to Warm the surface of the bushing or to maintain a definite temperature inside the bushing to control the electrical characteristics of the capacitance tap, or to maintain high insulation of the oil to preventit taking up water.

I claim:

1. The combination with a bushing insulator, of means accessible at apoint above the lower end of said insulator for draining the filling fluid from the interior of said insulator.

2. The combination with a bushing insulator having a flange between the Aends thereof for supporting said insulator, of means accessible at a point above said flange for draining the uid from the interior of said insulator.

3. The combination with a bushing insulator having a drain opening at the lower end thereof, of a closure for said opening, and means accessible at a point above the lower end of said insulator for opening said closure.

4. The combination with a bushing insulator having a flange between the ends thereof for supporting said insulator, said insulator having a drain passage at the lower end thereof, of a closure for said drain passage, and means accessible at a point above said iiange for operating said closure to open and close said drain passage.

5. The combination with a bushing insulator, of a conduit having an intake opening in the interior of said insulator near the lower end thereof, said conduit having a discharge opening adjacent the upper end of said insulator.

6. 'I'he combination with a bushing insulator having one end thereof adapted to extend into a closed housing, of a discharge conduit having an intake opening within the interior of said insulator adjacent the lower end thereof and having an outlet opening at a point accessible from the outside of said housing when said bushing insulator is in place in said housing.

rI. The combination with a bushing insulator having a flange thereon for supporting saidv insulator in a housing, a conduit having an intake opening in the interior of said insulator adjacent the lower end thereof, and an outlet opening outside oi said housing adjacent said iiange.

8. The combination with a bushing insulator, of a drain pipe extending through said insulator adjacent the axis thereof and having an intake opening at the lower end of said insulator and an outlet opening at the upper end of said insulator.

9. The combination with a bushing insulator having one end thereof arranged to extend into a closed housing, and means forming a drain for said insulator having an intake opening within said insulator adjacent the inner end thereof, and an outlet opening accessible from a point outside of said housing.

10. The combination with a bushing insulator having one end thereof arranged to extend into a closed housing, of dielectric material forming a drain for said insulator having an intake opening within said insulator and adjacent the inner end thereof and having an outlet opening outside of said housing and below the upper end of said insulator.

l1'. 'I'he combination with a bushing insulator having a flange between the ends thereof for supporting said insulator with one end thereof extending into a closed housing, dielectric means forming a drain passage having an intake opening within said insulator and adjacent the inner end of said housing and having an outlet opening outside oi said housing and adjacent said flange.

i2. The combination with a bushing insulator having a drain conduit for draining the nlling liquid from the interior of said insulator, said conduit comprising a dielectric baille disposed within said bushing insulator.

i3. A bushing insulator comprising a dielectric shell, a conductor extending through said insulator, Aa iiange secured to said insulator between the ends thereof ior supporting said insulator with one end thereof extending into a closed housing, a tubular dielectric baille surrounding said conductor, and an outlet opening having tight connection with the interior of said baille and extending outsideof said insulator for withdrawing the nlling liquid from the interior of said insulator through said baiile.

14. The combination with a bushing insulator, of means for heating the interior of said insulator to maintain a desired temperature therein and temperature regulated means for controlling said heating means.

15. The combination with a bushing insulator having a capacitance coupling connected therewith, of means for heating saidinsulator to control the characteristics of said coupling.

16. The combination with a bushing insulator having a capacitance coupling connected therewith, of means lling the interior of said bushing insulator, and means for heating said filling material to control the characteristics of said capacitance coupling.

17. The combination with a bushing insulator having a filling liquid therein, of means for heating the liquid in said insulator to control the temperature of said insulator, and a thermal device within said insulator for controlling said heating means.

1s. The'combination with a bushing insulatcr having a capacitance coupling therein, of a filling medium for said insulator forming at least part of the dielectric element of said coupling, and means for heating said illling medium to control the electrostatic properties thereof and to prevent accumulation of moisture on the outside of said insulator.

19. 'I'he combination with a. bushing insulator, of lling fluid within said insulator, a conduit having an intake opening adjacent the lower end of said insulator, and an outlet opening above the lower end of said insulator, a second conduit having connection with the outlet opening of said first-named conduit and having another connection with the interior of said insulator, and means for heating and circulating the filling fluid through said second-named conduit to control the temperature of the fluid within said insulator.

20. The combination with a bushing insulator, of a liquid filling medium for said insulator, of a conduit of dielectric material disposed within said insulator and extending upwardly from the lower portion thereof and having an outlet to the exterior of said insulator, and a connecting conduit of conducting material outside of said insulator.

2l. The combination with a conductor, of means comprising a. member of conducting material and a dielectric forming a capacitance coupling with said conductor, and means for regulating the temperature of said dielectric for controlling the electrical characteristics of said capacitance coupling.

22. The combination with a bushing insulator, of a capacitance coupling comprising a dielectric within said insulator, and means for regulating the temperature of said dielectric for controlling the electrical characteristics of said capacitance coupling.

23. The combination with a bushing insulator, of an insulating filling medium for said insulator, a capacitance coupling connected with said insulator, and means for regulating the temperature of said filling medium to control the electrical characteristics oi said capacitance coupling.

. ARTHUR O. AUSTIN.