US2689944A - Electric jumper and contact - Google Patents

Description

Sept. 21, 1954 T. E. CURTIS ELECTRIC JUMPER AND CONTACT Filed July 23, 1949 '/////l//{//I/I/I//Il//I//////////////////////l.7/ 'Il/I/l//I/l/l/l//l/l.V/l/I//AV/l/l/ 2 Sheets-Sheet 1 77-/OMAS E CURT/S INVENTOR.

AGENT Patented Sept. 21, 1954 &689344 ELECTRIC JUMPER AND CONTACT Thomas E. Curtis, Hampton, Ga., assigor to Southern States Equipment Corporation, a corporation of Georgia Application July 23, 1949, Serial No. 106345 4 Claims.

This invention relates to electric circuit-interrupting devices such as switches, fuses, and the like, particularly those for outdoor use on high-voltage circuits. object of this invention is to provide jumper means whereby the mechanical functioni of a device such as an electric switch may be tested while the device is in service.

A further object is to provide means whereby a high-voltage fuse Cartridge may be removed for inspection or replacement without interruption of the load supplied by the fuse. Heretofore it has been necessary to obtain clearance on the use in order to inspect the fuse element for possible deterioration after long service. Frequently alternative sources of power are not available, and it has been necessary to interrupt the service, causing considerable inconvenience and expense.

The jumper would also be useful for maintaining service while automatic switching equipment was tested. such switching systems are often quite complex and sometimes involve load-break switches. These systems frequently supply service for long periods of time without Operating mechanically, and yet are called upon for dependable operation under extreme conditions whenever necessary. This jumper would provide a means of maintaining service while the switching equipment was operated for testing purposes.

Another object is to provide such a jumper which is simple and economical in constructon, and which is adaptable for use on any circuitinterrupting device of the general types used on high-voltage electric systems. It is the well established practice to mount all such high voltage circuit interrupting devices upon insulator units which conform to established standard specifications. Such an insulator unit includes a flat topped metal cap afiixed to the top of the porcelain and the cap is drilled and threaded to receive bolts which are used to secure the current carrying members to the top of the insulator.

'The size of the bolts and the diameter of the bolt circle is specified for each size of insulator unit.

See Patents Nos. 1,560,998, 1,635,o49, 2,231,992 2,521,826.

Another object is to provide new members which can readily be attached to existing apparatus, thereby providing supporting means for the jumper.

Figures 1 and 2 show respectively the upper part and the lower part of one form of jumper embodying the features of this invention, the hole !4 being shown in each figure, and Figure 1 being partially in section; Figure 3 is a partial view to the same scale showing the top of one form of insulating switch stick which could be used to operate the device shown in Figures 1 and 2. The switch stick and a jumper supported thereon are together designated as the jumper assembly. Figures 4, 5, and 6 drawn to a smaller scale show successive steps in the operation of the jumper shown in Figures 1 and 2 in conjunction with a high-voltage circuit-interrupting device such as a switch, fuse, or the like; Figure 7 drawn to a larger scale is a plan view of one type of metallic stationary contact which is adapted for mounting between the terminals of a circuit-interrupting device and their respective insulating supports, and which is co-operable with a jumper shown in Figures 1 and 2; Figure 8 to the same scale is a side elevation of the member shown in Figure 7.

Referring to Figura 1, a jumper l has an upper jumper contact 2 fastened to a tubular housing 3 by means of screws l, 4. The upper contact 2 may be made in any convenient shape, but preferably it is made annular. At the lower extremty of the upper contact 2 is a hole 5 which is inside the cover or housing 3. One end of a helical extension spring 6 is hooked to hole 5, and the other end is hooked to an eye 'i ormed in end of a link 8. A similar eye 9 in the other end of link 8 is hooked to a hole !0 in the lower jumper contact li. A shoulder IZ of lower contact l l bears against the end of the cover 3 when end members 2 and H are free. The relative lengths of the cover 3, the spring 6, and the link 8 are such that the shoulder !2 on lower contact ll is held rather loosely against the end of the cover or tubular housing 3 when the jumper contacts 2 and ll are free.

A flexible metallic conductor [3 provides a low resistance electrical path between jumper contacts 2 and li. One end of the conductor 13 is fastened to upper jumper contact 2, preferably by soldering. conductor [3 passes inside the coils of spring 8, makes several turns around link 8, and is fastened to lower jumper contact H in a manner similar to the junction with upper end member 2. The purpose of coiling conductor !3 into several turns about link 8 is to provide for axial movement of lower end member ll with respect to upper end member !Z while the two are joined by conductor !3. It is apparent that the above described arrangement is readily adaptable for use under any of a large number of different voltage conditions. In almost every application of the jumper, the terminals to be bridged are disposed vertically, one above the other, or with one terminal at a higher level than the other so that all or an appreciable portion of the weight of the parts is taken by the upper terminal. A jumper for high voltage application must have a longer cover or housing 3, a longer link 8, and possibly a longer conductor [3 than does a jumper for a lower voltage application. Since any increase in the length of link 8 and of conductor !3 would not materially increase the loading of spring 6, and since the vertical com.- ponent of the weight of the relatively heavy cover 3 is taken by the upper contact member 2', the loading of spring 6 and the resulting contact pressure at contact ll is substantially independ ent of the voltage rating or physical size of the jumper. Thus by the invention substantially uniform contact pressure is achieved' for 'all voltage ratings and this highly desirable result is" achieved with a minimum of special parts. Statedotherwise, jumpers of all voltage ratings use the same parts except for the housing or cover 3, the link 8 and possibly the conductor !3 although it is possible that a standard' length for the conductor l 3 could be found which would be satisfactory for all voltages, since any surplus length for low Voltage jumpers probably could be coiled within the housing cover 3 in any suitable manner if desired.

Lower jumper contact ll may be made in any of several possible forms. A simple ring would be satisfactory, but the arrangement shown is preferred. A large ring M is formed in lower jumper contact ll near the shoulder 12. A hol'- low cylinder [5, having a length several times greater thanits.. diameter joins the ring l4' opposite shoulder !2, such that the hollow cylinder !5 is co-axial with cover 3. Ring !4 and cylinder are integral parts ofclower jumpercontact H.

One type of insulating switch stick in common use is shown in Figure 3. To an insulating rod !6 is fastened a head ll', consisting of a cylindrical body !8 with a cone-shaped tip !9, and having a laterally extending finger at right angles to the cylindrical body !8, and spaced some distance from the conical tip [9. The form of invention here shown uses a socket designed for use with an insulating stick havingsuch a head. The open end of the hollow cylinder 15' has a curved slot 2| designed forc engagement with the lateral ly extending finger 26 of the insulating stick head I'l when the cylindrical body !81 is inserted in the hollow cylinder !5 in a bayonet-type joint. The entire jumper I shown inFigures 1. and'2 can thus be supported by the switch stick,. and this jumper assembly is all in alignment, so itis easily handled by the insulating rod\ IS'.

One use of the jumper I shown inE'gures. 1 and 2 in conjunction with a high-voltage circuitinterrupting device is shown inFigures 4, 5, and 6. Referring to Figure 4, switch stick .head i l'l is engaged with lower contact ll, andithe jumper I is raised into position so that the upper. contact 2 is engaged with a laterally extending stationary contact 22 which may be part of one terminal 23 of alcircuit-interrupting device 24 such? as a switch, fuse, or the like. Referring to Figure 5, with the upper end member 2 of the. jumper i engaged with stationary contact 22, an axial pull is applied to the insulating rod !6, thus extending spring 6 and increasing the spacing between upper contact 2 and lower contact I I simultaneously lower contact ll is moved laterally by means ofinsulating rod IE' so thatilower contact H is engaged withanother stationary contact25 on a second terminal 25 of circuit interrupting device 24, contact 25 being similar in form to contact 22. The normal length of the jumper l is purposely made shorter than the spacing between stationary contacts 22 and 25 so that when jumper contacts 2 and l l are engaged respectively with stationary contacts 22 and 25 the jumper contacts 2. and ll are held: in firm contact with. their" respective stationary" contacts 22 and 25 by the tension of spring 6. After the jumper l is thus engaged, as shown in Figure 6, the head l'l of the switch stick may be rotated and then 'withdrawn from engagement with lower contact' H. An` electrical path of adequate capacity isthereby established between terminals 2.3; and' 213 of circuit-interrupting device 24, so that the bridging means 21, which may be a switch'blade', fuse cartridge, or the like, may be rem'oved without affecting the current which may be fiowing through the device between terminals 23 -and.2fi. And with thelong switch stick removed,the compact jumper is not in theway of anything else.

After bridging means 21 is restored to engagement withterminals 23 and26,' the jumper l may be. removed by the reverse of the procedure described above. The head ll on the switch stick is insertedin the open end of the hollow cylinder 15- and engagedby ai combined thrusting and rotary movement. An axial pull is applied'to the rod I 6 combined with a lateral movement, to disengagelower jumper contact Il from stationary contact25`. Thevjumper I can then be lifted from engagement with stationary contact 22', thus restoring the circuiteinterrupting device 24 to its normal Operating condition.

stationary contacts 22 andi25 can be made as integral parts ofvterminals 23 and. 26 respectively. A more satisfactory method would be tolmake separate contact. members 28, as shown in Figures. 7' and 8,' adapted for mounting between terminals 23 and.26"and.their respective insulating supports 2`9` and 30.' These members preferably; are made withtheir hook portions in the same plane as the flatplate portion and are symmetrical so 'that identical parts could .be used with both terminals 23 and 26, and they could be provided with.various sets of holes conforming tovarious standardizeddrillings for insulator Caps sothat identical parts could be attached to any circuit interrupting device on which .it might be desirablet tousethe jumper l. It will be observedmthat. the hook has. a .surface which is disposedstangentially relative to the` point on the periphery of the flatplate portion from which the hook projects. This constructional feature makes it possible. to preserve the normal spacing between. the, terminals oni. which two of the hooked contacts are mounted and. also avoids sharp points whichcould provide surfaces from whichcorona would discharge. By arranging the projections as shown in the drawing, a jumper of minimum length and weight canbe used.

The. jumper l alternatively can be used in conjunctionwith a pair. of insulators which are adjacentto butnot identical withthe insulators supporting the fuse, switch, or other device which is to be by-passedbyw means of the jum er.

Since the spacing between terminals of circuitinterrupting devices of a` given voltage rating have become more or less standardizedthroughout the industry, variousiumpers l, as shown in Figures 1`and.2, could be made, each to fit devices of aparticular.voltagerating. Contacts 2 and l l .andspringfiicould beidentical for any-voltage rating, and various length assemblies could be constructed by varying the lengths of cover 3, link 8, and conductor !3.

I claim:

1. As an article of manufacture for use as a hooked contact in association with an electrical terminal, a unitary contact member comprising a flat plate having a substantially circular periphery and a solid midportion and formed with a series of perforations disposed concentrically relative to the periphery of the plate, and a short hook projecting from one part of the periphery of the plate, said hook having a surface thereoi disposed tangentially of said one part of the periphery of the plate.

2 As an article of manufacture for use as a hooked electrical contact attachable to a terminal-supporting insulator unit by insertion between the terminal and its supporting insulator unit, a unitary contact consisting of a thin fiat plate having a curved periphery and a solid mid- .portion and with a relatively short hooked contact projecting laterally from one portion of the periphery of the said plate, said hooked contact being disposed in substantially the same plane as said plate and a surface of said hooked contact being tangential relative to said one portion of the periphery of said plate.

3 13. A jumper for interconnecting an upper electric terminal with a lower electric terminal, said jumper comprising a first contact engageable with the upper terminal, a second contact electrically connected with said first contact, a tubular housing of insulating material, said first contact being aixed to one end of said housing and said second contact being disposed at the other end of said housing in axially slideable 'relationship thereto and with its lower end portion projecting axially from said housing and having a cavity therein constructed to form a temporary operative connection with a switch stick and also formed to engage the lower terminal, said housing being supported by said first contact and the upper terminal when said contacts are in operative engagement with said terminals, a tension spring disposed in said housing with one end thereof connected to one of said contacts, and a link disposed in said housing with one end thereof connected to the other end of said spring and with the other end thereof connected to the other of said contacts, said spring and said link being efiective to bias said contacts toward each other.

4. A jumper for interconnecting a pair of spaced electric terminals, said jumper comprising a tubular housing, a first contact disposed at one end of said. housing and being engageable with one of said terminals, a second contact disposed at the other end of said housing in axially slideable relation thereto and with at least a portion of said contact being outside of said housing. at all times, said portion of said second contact being engageable with the other of said terminals and having a shoulder engageable with the end of said housing to determine the minimum spacing between said contacts, said portion of said second contact also being formed with a cavity therein to receive and form a temporary operative connection with one end of a switch stick, means for biasing said contacts toward each other, and means for electrically interconnecting said contacts.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 22,412 Shultz' Dec. 21, 1943 1,378,801 Lamb May 17, 1921 1,702,235 Steinberger Feb. 12, 1929 2,287,499 Smith June 23, 1942 2304307 Donaghue Dec. 15, 1942 2,306,661 Gengler Dec. 29, 1942 2,347,851 Steinmayer May 2, 1944 2,477,653 Roane Aug. 2, 1949 FOREIGN PATENTS Number Country Date 17,382 France Aug. 22, 1913 (Addition to 443,(3'74) 174,025 Great Britain Jan. 19, 1922

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