US2412926A - High voltage protective link - Google Patents

Description

Dec. 17, 1946- E. A. THQMPsQN p HIGH VOLTAGE PROTECTIVE LINK Filed Aug. 26, 1942 3 Sheets-Sheet l lNVENTOR ATTORNEY 5702/; A. Thompson.

WITNESSES:

Dec. 17, 1946."

E. A. THOMPSON HIGH VOLTAGE PROTECTIVE LINK Filed Aug. 26, 1942 3 Sheets-Sheet 2 WITNESSES:

EAMWALL INVENTOR Elvin A. Thompson.

BYi

NEY

ATI'OR Dec. 17, 1946.

E. A. THOMPSON HIGH VOLTAGE PROTECTIVE LINK Filed Aug. 26, 1942 3 Sheets-Sheet 3 1 rm as 46' y I 44 43 44 i l. E i

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Patented Dec. 17,1946

HIGH VOLTAGE PROTECTIVE LINK Elvin A. Thompson, Sharon,

Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Application August 26, 1942, Serial No. 458,210

transformers, it has become customary practice to provide a fusible link or conductor in the high voltage circuit positioned in the insulating fluid of the apparatus for interrupting the connection of the apparatus to the high voltage circuit upon a short circuit of the transformer windings. Such a power transformer assembly is described in Patent 2,1Q8,489, issued to F. L. Snyder on April 23,, 1940, and assigned to the same assignee as this application.

In such electrical apparatus, it has been customary to mount the protective link device directly on the lower end of the high voltage bush ing below the top level of the insulating liquid or to mount it On a separate support near the lower end of the high voltage bushing. When the fusible conductor of such a protective device is fused to interrupt the circuit, it is necessary to replace the fused conductor, and in order to .do this, it has been necessary to lower the level of the insulating liquid within the apparatus casing suiiiclently below the level of the protective device as to permit a person to enter the casing through a manhole in the cover of the apparatus and replace the fusible conductor element. It is also frequently necessary to remove the high voltage bushing from its mounting in order to apply th protective link.

It is an object of the invention to provide a protective device for use in apparatus of the character described in which the protective de vice may be removed and the fusible element re= viewed without the necessity of lifting the bushing or of draining the oil below its normal level.

It is a further object of the invention to pro vide a protective device for use in apparatus or" the described in which an operator lira-y remove the fused conductor and r place it with a new one without the necessity for entering the or casing of the apparatus.

@ther objects advantages of the invention will be apparent from the following description oil a preferred embodiment of the invention, ref= erence being had to the accompanying drawings,

which:

Figure l a vertical sectional view of electri= cal apparatus to which my invention is applied taken the line oi Fla. 2;

6 Claims. (01. 200-) Fig. 2 is a top plan view of the apparatus;

Fig. 3 is a vertical sectional view or the protective device that is mounted in the cover of the electrical apparatus;

Fig. 4 is an enlarged sectional view taken along the line IV-IV of Fig. 3; and

Fig. 5 is an enlarged sectional view of a portion of the device shown in Fig. 4.

Referring to the drawings, a tank or casing ii is provided having a cover it and which may include a compartment H for containing'a, main power transformer, a compartment It for containihg tap changing mechanism, and a compertinent it for containing metering and control mechanism, as well as other compartments such,

for example, as for containing a low voltage circult breaker between the transformer windings and the low voltage terminals of the apparatus. A lightning arrester i6 is shown mounted above the cover of the apparatus having one terminal ll grounded on the apparatus casing and the upper terminal l8 connected to a high voltage circuit conductor it) which is connected also to the terminal stud 2! of a high voltage bushing 22, the lower end 23 of which is connected through terminals 2t and 25 of a protective device it to the winding terminals ill of a main power transformer 28. As shown in Fig. 2, there will be three lightning arresters and three high voltage terminal bushings 22 for a threemhase power transformer, and likewise three low voltage terminal bushings Si having terminal studs con nected to low voltage lightning arresters also to the low voltage circuit conductors through which power is supplied from the apparatus.

Manhole covers 3 3 are provided in the cover it of the apparatus to permit workmen to enter the apparatus casing for necessary repairs and smaller covers are provided, three in nuinicer. directly behind each of the three high voltage bushings for providing access to the protective devices 526 which devices are more clearly shown in Figs. and 5.

The protective device includes a fixed por tion permanently mounted within the apparatus and including a base and a barrier or wall 8? of insulating material extending upwardly from the base to a level 33 below the level of the oil within the apparatus. The carrier wall is also provided with openings 39 to permit the flo of the cooling and insulating fluid in and about the parts of the protective device within the barrier wall The terminals 26 and 25 are mounted in the wall or barrier 3'] and provided on their inner ends with flat vertically extend-1m contact.

3 members 4| for engaging contact members 42 mounted upon a movable portion of the protective device which includes a cover or plate 43 normally supported below the manhole cover 35 in any suitable manner as by lugs 44, and provided with a handle 45 for raising the plate 43 and the movable portion of the device supported thereby from within the apparatus after removal of the manhole cover 35.

Extending downwardly from the plate 13 are supporting members 46, here shown as four in number, which are attached in any suitable manner to spacer members 41 shown at various levels along the vertical supporting members 56. Two of the vertical spacer members 46, as best shown in Fig. 4, serve as guide members fitting within channels in guide members 58 extending downwardly within the barrier wall 31. Another of the supporting members d6 serves as a support for the contact members 62 which serve as terminals of the removable portion of the device for con- Modifications in the apparatus illustrated and described may be made within the spirit of my invention, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

1. In an electrical apparatus including a casing having a liquid insulating medium therein, a cover provided with an opening therein, insulating bushings mounted on and extending through the cover of the casing through which extend leads connecting the apparatus to line circuit conductors, a protective device for the electrical apparatus positioned within the casing and mounted below the opening in the easing cover, said protective device including a base portion and a tubular barrier wall member exnecting a fusible conductor 5| between the terminals and 25 of the protective device when the movable portion 40 is in its normal illustrated position. The protective device including the fusible conductor 5! may correspond in principle to that illustrated and described in Patent No. 2,223,726, to J. K. Hodnette, issued December 3, 1940, and assigned to the same assignee as this application. The fusible conductor 5| is shown attached between terminals 52 and 53 by set screws 55 and 55 respectively, the upper terminal 52 bein connected to the upper contact member 52 through a terminal head 56, conductor 57, and the lower terminal 53 being connected to the lower contact member 52 by a cable 58.

The fusible conductor element 5| is supported from the upper plate 53 through vertical members 5i which are connected in any suitable manner as by a pin 62 to the terminal head 56. A tube 63 of fiber or other suitable material extends downwardly from the upper terminal 52 about the fusible conductor 5! for aiding in the blowout characteristics of the are formed when the device operates to interrupt the circuit in a manner now Well known. The lower terminal 53 is mounted in a, piston 55 normally positioned in a bore within a tubular member 65 of insulating material which may be supported from the terminal head 56 through members 66 and 67.

When the current carried by the apparatus exceeds the safe value sufiiciently to cause the fusible conductor Fat to fuse and draw an areunder the insulating liquid in which it is immersed, the gases produced by the arc cause the I piston 65 that is attached to the end of the cable 58 to be rapidly ejected from the bore within the tubular member 65 so as to rapidly increase the length of the arc which is extinguished in the insulating liquid surrounding the fusible conductor.

When the fusible conductor 5| has melted and interrupted the circuit, a, similar fusible conductor may be replaced by removing the manhole cover 35 and lifting the entire movable portion of the protective device by the handle 45 from within the apparatus casing, causing the contact members 42 to separate from the contact members il, Thus the entire structure positioned within the vertical supporting members 46 is removed from the apparatus permitting a. new fusible wire 5| to be inserted without the necessity of lifting the heavy high voltage bushings or draining the oil to permit a workman to enter the casing of the apparatus.

tending upwardly therefrom and provided with openings therein to permit the flow of the liquid insulating medium within the barrier wall, and guide members extending inwardly from the barrier wall to guide the removable portion against rotation while permitting vertical movement thereof, a pair of fixed contact members mounted on thebarrier wall, one connected to the inner end of a circuit conductor supplying energy to the apparatus and one connected to the apparatus, and means for supporting said fixed con tact members beneath the normal top level of the liquid dielectric, and a removable portion containing a fusible conductor, said removable portion being insertable and removable through the opening in the apparatus cover and having slidable contact members adapted for engaging the fixed contact members for connecting the fusible conductor between the bushing terminal and the apparatus terminal and positioning the fusible conductor below the top level of the liquid dielectric.

2. In a casing containing an electrical transformer having high-voltage and low-voltage windings, and containing a liquid dielectric with in the casing in which the transformer is immersed, and having highwoltage insulating bush ings mounted on the cover of the casing through which extend leads connecting said high voltage windings to high-voltage circuit can ductors, a protective device associated with high-voltage circuit conductor including eon ductor which will fuse when subjected to predetermined electrical conditions positioned within the casing and mounted below an opening in the apparatus cover below the top level of the liquid dielectric, said protective device compri tubular barrier wall permanently mounted with Q in the apparatus casing beneath the top level of the liquid dielectric and provided with a pair of terminals, one terminal being connected to the inner end of the bushing lead andthe other terminal being connected to the high-voltage winding, and a removable portion containing the fusible conductor insertable into the barrier through the opening in the apparatus cover and having terminals therein for engaging the ter= minals in the barrier wall for connecting the I fusible conductor between the high-voltage terminal lead and the high-voltage winding and positioning the fusible conductor below the top level of the liquid dielectric.

3. In a casing containing an electrical apparatus, a liquid dielectric within the casing in which the electrical apparatus is immersed and having insulating bushings mounted on and. extending through the cover of the casing through which extend leads connecting the apparatus to line circuit conductors, a protective device for the electrical apparatus positioned within the easing and mounted below an opening in the apparatus, said protective device comprising a fixed portion permanently mounted within the apparatus casing and a removable portion, the fixed portion comprising a tubular barrier wall of insulating material extending upwardly from a supporting base and having an open upper end terminating below the opening in the apparatus cover at an elevation below the top level of the liquid dielectric, guide members carried by said barrier wall for governing the axial position of the removable portion when inserted into the barrier, and fixed contact members carried by the barrier, the removable portion containing a fusible conductor and having slidable contact members therein for engaging the fixed contact members carried by the barrier for connecting the fusible conductor between the bushing terminal and the apparatus terminal and positioning the fusible conductor below the top level of the liquid dielectric, said removable portion having' guide members for cooperating with the guide members on the fixed portion of the device for guiding the contact members into circuit closing positions. I

4. In a casing containing an electrical transformer having high-voltage and low-voltage windings, and containing a liquid dielectric within the casing in which the transformer is immersed, and having high-voltage insulating bushings mounted on the cover of said casing through which extend leadsconnecting said high-voltage windings to high-voltage circuit conductors, a protective device associated with each highvoltage circuit conductor including a conductor which will fuse when subjected to predetermined electrical conditions positioned within the casing and mounted below an opening in the apparatus cover below the top level of the liquid dielectric, said protective device comprising a tubular barrier wall permanently mounted within the apparatus casing beneath the top level of the liquid dielectric and provided with a pair of terminals, one terminal being "connected to the inner end of the bushing lead and the other terminal being connected to the high-voltage winding, and a removable portion containing the fusible conductor highs-voltage terminal lead and the high-voltagewinding and positioning the fusible conductor 6 protective device including a fixed portion mounted within the casing and a removable portion cooperatively related thereto, said fixed portion including a base portion and a tubular barrier wall member extending upwardly therefrom andprovided with openings therein to permit the flow of the liquid insulating medium within the barrier wall, and guide members extending inwardly from the barrier wall to guide the removable portion against rotation while, permitting vertical movement thereof, a pair of fixed contact members mounted on the barrier wall, one of said fixed contact members being connected to the inner end of the bushing lead and the other one of said fixed contact members being connected to the apparatus, and means for supporting said fixed contact members beneath the normal top level of the liquid dielectric, and a removable portion containing a fusible conductor, said removable portion being insertable and removable through the opening in the apparatus cover and having slidable contact members adapted for engaging the fixed contact members for connecting the fusible conductor between the bushing terminal and the apparatus terminal and for positioning the fusible conductor below the top level of the liquid dielectric, the removable portion having a plate member at its upper end an electrical transformer immersed in the liquid dielectric and having high-voltage and lowvoltage windings, a protective device associated with each high-voltage winding circuit conductor including a conductor which will fuse when subbelow the top level of the liquid dielectric, and

' guid members associated with said barrier wall and said removable portion for positioning the removable portion axially with respect to the barrier wall to insure engagement of the cooperating terminals carried by said'separableportion of said protective device.

5. In an electrical apparatus including a cas-,

ing having a liquid insulating medium therein, a cover provided with an opening therein, insulating bushings mounted on and extending through mounted below an opening in the apparatus, said 76 jected to predetermined electrical conditions positioned within the casing and mounted below an opening in the apparatus cover below the top level of the liquid dielectric, said protective device mitting vertical movement thereof, a pair of:

terminals, one terminal mounted in the barrier wall, one terminal being connected to a circuit conductor and the other terminal being connected to the high-voltage winding, said removable portion being insertable, into the casing through the opening in theapparatus cover and having terminals therein for engaging the terminals in the fixed portion for connecting the fusible conductor between the high-voltage terminal lead and the high-voltage winding and positioning the fusible conductor below the to level of the liquid dielectric.

nnvm A. 'rnomrson.

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