US3480898A

US3480898A - Combined fuse and switch operator assembly

Info

Publication number: US3480898A
Application number: US630330A
Authority: US
Inventors: Bertrand V Giegerich
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1967-04-12
Filing date: 1967-04-12
Publication date: 1969-11-25
Anticipated expiration: 1986-11-25

Description

Nov. 25, 1969 B. v. GIEGERICH 3,480,898

COMBINED FUSE AND SWITCH OPERATOR ASSEMBLY Filed April 12, 1967 United States Patent O 3,480,898 COMBINED FUSE AND SWITCH OPERATOR ASSEMBLY Bertrand V. Giegericli, Pittsfield, Mass., assignor to s(rgenlteral Electric Company, a corporation of New or v Filed Apr. 12, 1967, Ser. No. 630,330 Int. Cl. H01h 85/22 U.S. Cl. 337-4 4 Claims ABSTRACT OF THE DISCLOSURE A combined fuse and switch assembly especially useful in electrical apparatus, such as submersibledistribution transformers. The apparatus is provided with a fuse holder mounted in the interior of the apparatus. The fuse holder has a lower rotatable fuse contact which is hermetically sealed and connected to a switch mounted in the interior of the apparatus. The rotatable fuse contact operates the switch. A second fuse contact is provided in the fuse holder. A removable cover has the fuse secured thereto such that when the cover is placed on the top of the fuse holder, outside of the apparatus, such as a transformer, the fuse is inserted into the holder contacting both fuse contacts. Rotation of the fuse cover, to lock and seal the cover on the outside of the fuse holder, closes the internal switch. To remove the fuse, the cover must iirst be rotated to unlock the cover which opens the internal switch.

Background of invention This invention relates to electrical apparatus such as distribution transformers and more particularly to a combined fuse and switch operator assembly for use in such electrical apparatus.

There is presently a well defined, growing trend in the electrical distribution teld from overhead, open wire electrical distribution to underground, buried wire distribution. With this growing trend many utilities are evolving new operating procedures to develop safe, efficient operating practices for underground servicing. At the same time, the equipment manufacturers are attempting to build distribution equipment which may be used with these new operating procedures. Many types of distribution apparatus are now provided with removable fuses which may be readily removed from the outside of the apparatus and there may be replaced, in the event of faults which may occur within the electrical apparatus. With these types of removable fuses, many of the utilities require that a switch be provided in series with the removable fuse such that the switch may first be opened prior to the removal of the fuse. In many instances, in following these numerous operating procedures of utilities, the fuse is removed prior to operating or performing a service function on the electrical apparatus since the removal of the fuse provides a positive, visually verifiable, opening of the circuit to the electrical apparatus.

Many of these fuses are not considered as current interrupting devices in the manner of a switch, since they are not designed to be removed while the electrical current is applied to such fuses. In order to provide safe operating procedures for the removal of fuses, it is considered desirable to provide with such fuses, a switch operating device such that the switch in series with the fuse must be opened prior to the removal of the fuse. In those instances where switches are provided in series with the fuse, but are not required to be operated prior to removal of the fuse, it is of course, possible for a lineman or other service man working on the electrical apparatus to forget to open the switch prior to the removal of the Patented Nov. 25, 1969 ICC fuse. In such instances, as is well known in the art, the electrical arc built up in the removal of the fuse may be sufficient to actually blow the fuse out of the transformer or to cause a line to ground fault, which may injure the operator and also damage the equipment. Therefore it is considered desirable to provide a switch in series with the fuse, which switch must be opened prior to the removal of the fuse.

It is therefore one object of this invention to provide a combined fuse and switch operator assembly such that the fuse cannot be removed or inserted while the switch is in its closed or energized position.

A further object of the invention is to provide a sealed, removable fuse, where a fuse cover carries the fuse and causes opening of a series switch when the fuse cover is being unlocked prior to removal of the fuse.

Summary of invention Briey, in one form, the combined fuse and switch operator of this invention comprises a fuse holder mounted in an electrical apparatus. A rotatable fuse contact is provided sealed in the holder and connected to operate a switch internally of the apparatus. A fuse cover is also provided with the fuse secured thereto. When the fuse is inserted in the holder, the lower portion of the fuse iits into the rotating contact. As the fuse cover is turned to lock the cover and fuse in place in the electrical apparatus, the rotatable fuse Contact is rotated to close the switch. When the fuse cover is rotated to unlock the cover for removal of the fuse, the rotatable fuse contact moves the switch to its open or deenergized position, before the fuse can be removed.

The invention which is sought to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention, and the manner in which its various objects and advantages are obtained, as well as other objects and advantages thereof, will be better understood from the following detailed description of a preferred embodiment thereof, particularly when considered in the light of the accompanying drawing.

Brief description of drawing FIGURE 1 is a length-wise sectional view of a cornbined fuse and switch operator according to one embodiment of this invention;

FIGURE 2 is a top view of the fuse cover shown in section in FIGURE 1;

FIGURE 3 is a partial view, partially in section showing another form of fuse holder according to this invention; and

FIGURE 4 is a perspective view of a preferred form of rotatable fuse contact according to this invention.

Description of preferred embodiment This invention relates to a combined fuse and switch operating device in which the fuse is provided wtih a contact which connects with a rotatable fuse contact in a fuse holder. The rotatable -fuse contact is, in turn, directly connected to a switch operator which, on rotation, will either open or close a .series switch. The preferred ernbodiment set forth herein discloses the present specific construction believed most suitable for obtaining the various objects and advantages of this invention. Obviously, many changes may be made in various constructional details without departing from the scope of the invention herein defined.

Referring now to the drawing in which like numerals are used to indicate like parts throughout and referring particularly to FIGURE 1, there is shown one form of a combined fuse and switch operator assembly according to this invention. As is shown in FIGURE 1, a fuse holder shown as two parts, 12 and 14 of electrical insulating material .such as porcelain or the like, is secured to a Wall member 16 which may be, for example, the cover of an electrical apparatus, such as a submersible transformer. A cover member 18 is provided which seals in a water tight manner to fuse holder 10. The cover 18 carries a fuse 20 which makes electrical connection with fuse contacts 22 and 24, which are mounted in the lfuse holder 10. Fuse contact 22 is rotatably mounted in the bottom of fuse holder 10 and is hermetically sealed from the interior of the transformer by an hermetic seal 26 which may be, for example, an hermetic seal as described and claimed in application Ser. No. 623,451, filed Mar. 15, 1967, for Hermetic Seal for Rotating Shaft, by the inventor herein, and which is assigned to the same assignee as this invention and now abandoned. A switch operator or handle 28 is provided and fixed to the lower part of contact 22 as shown. The operator handle 28 rotates with the contact 22 to open or close a .switch (not shown) which is within the transformer or electrical apparatus and in electrical series with fuse 20.

Leads

30 and 32 are provided on the fuse holder 10, the lead 30 going to the switch (not shown) through which the apparatus is energized and the lead 32 leading to a bushing (not shown) which provides the electrical energy to the apparatus, for example, a submersible distribution transformer.

Referring specifically to the constructional details shown, the upper part 12 of fuse holder 10 is molded of electrical insulating material such as, for example, a porcelain material and is provided with a circular flange, such as 34, which is molded or cast in place into the upper part of member 12, as shown. Flange 34 may be attached to wall member 16 of the electrical apparatus in any desired manner, the present preferred manner being to Weld flange 34 directly to the wall 16 of the electrical apparatus. A pair of metal inserts such as, for example, L-

shaped flanges

36 and 38 are also molded or cast in place into the upper portion 12 and the lower portion 14, respectively. These

metal inserts

36 and 38 are in turn welded to a U-shaped metal member 40, which forms a portion of the electrical contact of the fuse holder 10. As can be seen from FIGURE 1 of the drawing, the metal insert 40 is connected, preferably by brazing, to a metal sleeve 42 which extends from metal insert 40 to the top of fuse holder 10, in the manner shown. As will be understood, the metal sleeve 42 is provided at its upper portion with a spring 44 to maintain pressure on the electrical contact 24 as is shown. Lead 32 which, as explained, goes to the bushing (not shown) of the electrical apparatus, is connected to a stud 46 which is mounted on the metal insert 40 in the manner shown. A second stud 48 may also be provided, if desired, for an additional connection of the electrical lead to the interior of the transformer.

The lower portion 14 of bushing 10 is provided with an L-shaped metal ilange 50 which is molded or cast in place in the lower end of the porcelain part 14. Flange 50 in turn is Welded to a lower plate member 52 which forms the bottom of the fuse holder 10. The rotatable contact 22 is rotatably mounted in the lower plate member 52 and, as mentioned, is provided with the hermetical sealing member 26, as shown. In the example shown in FIGURE 1 of the drawing, metal contact 22 is bolted to rotatable shaft 54 by means of a bolt member 56. Obviously, the rotatable shaft 54 and the fuse contact 22 may be made of one piece if desired. However, it has been found that, for purposes of assembly, it is better to make it in two parts as shown.

A rotatable cover member 18 is provided which has a flange member 58 as is best seen in FIGURE 2 of the drawing. As is shown in FIGURE 2, flange member 58 is provided with

cutout portions

60 and 62 which mate with the turned lugs 64 and 66, which are mounted on the cover or wall member 16 of the electrical apparatus. The flange 58 of cover 18 is also provided with

stops

68 and 70 which, as can be seen in FIGURE 2 of the drawing, will rotate to contact

lugs

64 and 66 to prevent further movement of the cover member 18. As will be understood, the cover member 18 is placed on the fuse holder 10 with

cutouts

60, 62 fitting down over the

lugs

64, 66. The cover is then rotated in a clockwise direction, as indicated by the closed arrow shown in FIGURE 2, until the

stops

68 and 70 contact lugs 64 and 66, in the manner shown in FIGURE 2. As will be understood, this will lock the fuse member 20 within fuse holder 10 and prevent any accidental removal thereof. The

lugs

64 and 66 extend high enough above cover 16 so that the fuse cannot be partially inserted to close the switch, but must be fully inserted so that flange 58 is held down by the lugs.

As is best shown in FIGURE l of the drawing the interior of cover 18 is provided with the insulating material 72 which is flared to cooperate with the conical shaped top 74 of the upper member 12 to fuse holder 10. The internal dimensions of insulation 72 in cover member 18 is smaller than the outer dimension of top 7`4 of fuse holder 10. This provides a pressure-tight lit, requiring insulation 72, which is preferably an elastomeric material to be stretched over top 74 of fuse holder 10. This provides a water-proof seal to the fuse holder 10 and also provides very high dielectric strength to the seal. It has been found that the dielectric strength is related directly to the stretch of insulation 72. It is believed that this is due to imperfections in the mating surfaces between insulation 72 and top 74 of fuse holder 10. The stretching of insulation 72 apparently brings these mating surfaces into closer contact, with fewer voids. As will be understood, as the cover 18 is placed over the conical top 74 of bushing 10, the insulation 72 will stretch and tighten on the top portion 74 of portion 12 to seal the bushing holder from any possibility of water entering through the cover member 118. It also provides an electrical seal capable of withstanding insulation test voltages.

Also connected to insulation 72 is an insulating tube 76 which in turn is connected to the upper fuse contact 78 of fuse member 20. In the embodiment shown, fuse contact 78 is bolted to the insulating tube 76 by means of bolt 80. As will be understood, the upper contact 78 of fuse 20 may be pinned or brazed or otherwise firmly fixed to fuse 20. The lower contact of fuse 20 is indicated at 82 and, as shown, is a split contact having a spiral spring 84 therein and fits within the sides of the contact 22 of fuse holder 10. As will be understood, contact 82 is also pinned or brazed or otherwise firmly connected to fuse 20. The spiral spring -84 aids in providing a firm electrical contact between fuse contact 82 on fuse 20 and the fuse contact 22 in fuse holder 10. As will be understood from the foregoing, rotation of fuse cover y18 to lock it in place, or to unlock it, Will in turn rotate fuse 20 through tube 76, bolt -80 and contact 78 which will, in turn, rotate contact y82 which will rotate the contact 22 to thereby rotate switch operator 28 to either open or close the internal switch (not shown) of the electrical apparatus.

As is shown, particularly in FIGURE 1, the cover 18 is provided with a raised lug 86 which has an opening 88 therein for reception of a hook stick or the like. Thus, as will be understood, an operator such as a lineman may place a hook stick (not shown) into opening 88 and thereby insert fuse 20 into fuse holder 10 and in locking such fuse within the fuse holder, close the switch through operator 28. In a similar manner, the lineman using a hook stick in the opening 88 of lug 86', may unlock the fuse cover 18 by rotating it in a counterclockwise direction, as indicated by the arrow labeled open in FIG- URE 2, to thereby open or deenergize the switch. After cover 18 is unlocked, which opens the switch, fuse 20 may be removed from fuse holder 10.

Fuse holder 10 is also provided with an insulating sleeve or tube 90 which surrounds fuse 20. This insulating sleeve 90 is placed between fuse 20 and metal sleeve 42, as shown in FIGURE l. The insulating sleeve 90 eX- tends from the top of fuse 20 to the bottom of fuse holder` 10. As can be seen, this construction allows the placing of contact 46 and lead 32 below the oil level of the electrical apparatus. It is desirable to have this below the oil level to provide adequate insulation from contact 46 to the wall member A16. If only air were used as insulation it would be necessary to substantially increase the length of fuse holder below wall member 16. Also the insulating sleeve 90 provides adequate insulation to prevent any arcing from the lower end of fuse to the lower end of metal sleeve 42, after the fuse has interrupted the circuit.

FIGURE 3 shows a modiiication of the fuse holder in which the fuse holder is made of an electrically insulating material such as, for example, a molded epoxy resin. In this type of one piece fuse holder, indicated at 10', a metal insert such as 46 and 48 may be molded directly into the fuse holder and make contact with the metallic sleeve member 42 which will form one of the contacts for the fuse 20 as is shown in FIGURE 3. insulating sleeve 90 is also provided, as shown. In this manner, as will be understood, the fuse holder may be made of a single piece of insulating material rather than the two piece porcelain holder as is shown in FIGURE 1 of the drawing. As will be clear to those skilled in the art, the fuse contacts for the fuse 20' will operate in the same manner as previously discussed, for opening and closing a switch (not shown) prior to the removal or after the insertion of the fuse 20.

FIGURE 4 shows the present preferred construction of the lower fuse contact 82 and the rotatable fuse contact 22. As can be seen from FIGURE 4, rotatable fuse contact 22 has a square opening 23 which accepts the square shank 55 of rotating member 54. Contact 22 includes a U-shaped contact portion 25, as shown. Preferably both 22 and 54 are brass castings. Contact 82 also includes a U-shaped portion 83` which iits into U-shaped member 25. A spiral metal spring member 84 tits in opening 8S in portion 83 to provide constant outward pressure on the arms of the U-shaped portion 83. As will be understood, spring 84 will allow portion 83 to be inserted into U-shaped contact members 25', providing rm electrical contact between

members

22 and 82, and providing the rigidity necessary to operate the switch, without requiring excessive push-in or pull-out forces between

contacts

22 and 82. Of course, the mating U-shaped portions allow the fuse 20 to rotate contact 22, when the fuse 20 is rotated with cover member 18.

While there has been shown and described the present preferred embodiment of this invention, it will of course be understood by those skilled in the art that various changes may be made. For example, the removable fuse with hermetic fuse holder may be used without the rotating contact, if desired. As will be apparent, these changes may be made Without departing from the spirit and scope of the invention, particularly as the invention is defined in the appended claims.

What is claimed as new and which it is desired to be secured by Letters Patent of the United States is:

1. A combined fuse and switch operator comprising:

(a) a fuse holder mounted in a wall portion of an electrical apparatus,

(1) said fuse holder having a metal flange molded therein, said flange rigidly |attached to the wall portion of the electrical apparatus,

(b) an electrical contact at the bottom of said fuse holder,

(1) lsaid electrical contact being rotatably mounted and being hermetically sealed yfrom the i11- terior of said apparatus,

(c) a switch operator, said switch operator mounted on said rotatable contact outside said fuse holder, land rotatable with said rotatable contact,

(d) a fuse mounted within said fuse holder, said fuse having one contact making electrical and mechanical connection with said contact in said fuse holder,

(e) a fuse cover, said fuse cover being rigidly lattached to said fuse,

(1) said fuse cover fitting on said fuse holder in one position and being rotated to a second position for locking said cover on said holder, rotation of said cover causing said fuse contact to rotate said rotatable contact to thereby rotate said switch operator.

2. A combined fuse and switch operator comprising:

(a) a fuse holder mounted in a wall portion of :an

electrical apparatus,

l(b) a rst electrical contact in the bottom of said fuse holder,

(l) said electrical contact being rotatably mounted in the bottom of said fuse holder,

(2) said rotatable contact being hermetically sealed from the interior of said apparatus,

(c) a switch operator, said switch operator mounted on said rotatable contact outside said fuse holder, and rotatable with said rotatable contact,

(d) a second electrical contact in a portion of said fuse holder remote from said iirst electrical contact,

(e) a cover member for said fuse holder,

(f) a fuse member, said fuse member rigidly connected to said cover member,

(1) said fuse member having a pair of electrical -contacts making electrical connection with said tirst and second electrical contacts,

(2) one of said pair of contacts making a mechanical connection with said first contact,

(g) locking means on said wall portion ofthe electrical apparatus,

'(1) said locking means receiving said cover member in one position,

(2) said cover member rotatable to a second position to lock with said locking means, rotatation of said cover member rfrom said one position to said second position rotating said rotatable contact to thereby rotate said switch operator.

3. A combined fuse and switch operator as claimed in claim 2 in which said fuse cover is provided with Ian internal elastomeric insulation, said elastomeric stretching over the top of said fuse holder to provide a water tight lit and an electrically insulating seal therewith.

4. A combined fuse and switch operator as claimed in claim 2 in which said rotatable contact is provided with a Ushaped portion to receive said one of said fuse contacts, said one fuse contact being a U-shaped member having a spiral spring therein to force said one contact into firm electrical connection with said rotatable contact.

References Cited UNITED STATES PATENTS 3,286,061 11/ 1966 Henderson 200--129` 2,958,750 11/1960 Lebens 337-205 2,648,740 4/ 1953 Heath 200-128 1,601,926 10/ 1926 Simpson 200-129 FOREIGN PATENTS 480,690 2/ 1938 Great Britain.

BERNARD A. GILHEANY, Primary Examiner D. M. MORGAN, Assistant Examiner U.S. Cl. X.'R. 337-486, 227, 234