US2709736A - Load break - Google Patents

Description

May 31; 1955 H. P. SCHNEIDER LOAD BREAK 3 Sheets-Sheet l Filed Feb. 29. 1952 IN V EN TOR. A. der' May 31, 1955 H. P. SCHNEIDER LOAD BREAK Filled Feb. 29, 1952 3 Sheets-Sheet 2 l v INVENToR.

HZ'orny May 31 1955 H. P. SCHNEIDER 2,709,736

LOAD BREAK Filed Feb. 29. 1952 3 Sheets-Sheet 3 ,ffy 4 INVENTOR. Hans. Schn r' United States Patent O i LOAD BREAK Hans P. Schneider, South Milwaukee, Wis., McGraw Electric Company, Milwaukee, poration of Delaware assigner to Wis., a cor- This invention relates to a load break to be used principally on an enclosed fuse cutout for electrical apparatus.

There are numerous occasions when it is necessary to inspect the electricai lines or to do some repair work on the lines, and of course, to do so requires interrupting the current. fuse cutout when opened provides an air gap but when a fuse cutout is opened manually it is apt to draw a large arc. This is dangerous to the safety of the lineman. A large arc may also burn the contact points which would lessen the eiiciency of the contacts. Therefore, it can be seen that if a way can be devised for opening a fuse cutout without drawing an arc, it would eliminate a dangerous hazard to the linenien and prevent burning of the contact points and destruction of the cutout h using.

One object of this invention is to provide an air gap in a fuse cutout without drawing an arc.

Another object of this invention is to shunt the current that passes through the air gap between the upper stationary contact and the upper movable contact of a fuse cutout while the door of the cutout is being opened.

And another object if this invention is to provide a load break sectionalizing device in which the operator may open the circuit with the assurance that the arc will be confined to a predetermined zone in the device and will be substantially extinguished without any possibility of ashover.

ther objects will appear from time to time in the course of the specification and claims.

l illustrate an embodiment of my invention in the accompanying drawings, in which:

Fig. l is a sectional view of the load break attached to the top of a fuse cutout, the load break in inactive position.

Fig. 2 is similar to Fig. l showing the load break shortly after arc interruption.

Fig. 3 is a side elevation showing a load break mounted on the top of a fuse cutout.

Fig. 4 is a front elevation showing a load break mounted on the side of a fuse cutout.

Like reference figures illustrate like parts throughout.

Referring to Fig. l, l show a fragment of a standard fuse cutout Il consisting of a porcelain body portion 2 with a hinged door 3. The hinged door 3 has an eyelet handle 4 to facilitate opening. On the inner side of the cutout door 3 is attached a fuse tube 5 which moves with the door. A movable contact 6 extends from the upper end ot' the fuse tube 5 through an opening in the door 3 to the outside of the fuse cutout, and this conductor serves as a Contact means when the load break is being used.

The load break 7 is mounted by means of a conductive support member d through an opening 9 in the upper end of the fuse cutout 1. Some cement means 16 is used to fasten the support member 8 to the fuse cutout. This support member 8 is also connected with the power line entering the fuse cutout.

The load breakf is composed of conductor elements and non-conductor tubular portions and a latch which 2,709,736 Patented May 31, 1955 lCC 2 operates the load break when it is tripped by the movable Contact 6 extending from the door 3 of the fuse cutout.

A conductive tubular member 11 has a cap closure i2 at its outer end and at the other end it is tted into a metal sleeve 13. This metal sleeve 13 is encompassed by a conductor band ltd to which the mounting conductive support member 8 is attached. At the opposite end ofthe sleeve t3 trom the tubular member 11 is a iibre tube 16 which ts into a grooved portion 17 of the sleeve 13. An arcing conductor ring l ts between the end of the fibre tube i6 and a shoulder in the sleeve 13.

A metal rod 19 is disposed longitudinally within the bre tube io. Rod 19 normally serves as an electrical connection from the interior to the exterior or" the load break device by means of providing it with an arcing contact 2t) in electrical contact with resilient arms 2S in circuit continuity with sleeve 13.

Arcing contact Ztl is maintained in axial alignment with rod 19 by screwing it into the end of a plunger 21 composed of an insulating material of plastic such as methyl methacryiate. A helical spring 22 in compression is interposed between cap i2 and the head portion 2in interiorly of plunger 2l. circumjacent a spring aligning shaft 3S.

It is apparent that arcing contact 2d may separate from resilient arms 23 under the action of spring 22 to disrupt the electrical continuity of the load break device, but this action is normally prevented by an axial counterforce maintained along rod 19 by reason of it being latched.

The conductor rod i has on its outer end a head member 24 of greater diameter than the conductor rod i9. A notch 25 on the side of the head 24 forms the means in conjunction with a latch 29 for holding the plunger 2l and rod 19 within the load break housing.

A shunt horn 25 which shunts the air gap between the upper stationary contact and the upper movable contact of the cutout is held in rigid association with the bre housing 16 by means of a ferrule 27' and locking means 2S. T he shunt horn 26 holds the latch 29 shaped to tit in the notch 2S and held in that position by a leaf type spring The latch 29 has an extension 29a which forms the tripping means for moving the latch out of Contact with the conductor head 24.

Positive electrical contact between the slidabie conductor head 2d and ferrule 27 is obtained by means of a U- shaped spring 31 anchored to the ferrule and strongly pressing against head 26? as seen in Fig. l. However, when the load break device has been tripped as illustrated in Fig. 2, spring 3l drops down into contact with rod 19 so that the current being interrupted passes from said rod to said errule 2'7 to horn Z6 without any air gaps being formed in the circuit. Therefore, all arcing occurs between arcing contact 2t) and arcing ring 1S during the operation ot' the load break.

The use and operation of my invention are as follows:

In Fig. i the load break is inactive, the door of the fuse cutout is closed and current is traveling through the fuse cutout. in Fig. 2, the door orc the cutout is open, the current has been shunted around the air gap between the stationary terminal and the movable contact 5 tirough the load break, the contacts separated, and the resulting arc extinguished by the higher air pressure within the nbre tube rushing out. This creates an air gap.

rThe mounting conductor 8 is electrically connected within the fuse cutout and a conductive path exists within the load break from the band 1d to the sleeve 13, to the resilient arms 23, to arcing contact 2u, to the conductor rod 19, to the head 24 of the conductor rod i9, to the said shunt horn 26 with its latch tongue 29 resting in the notch 25. Consequently, when the fuse cutout door is opened the movable Contact 6 reaches the said shunt horn 26 along its curved surface 25a which closes the circuit through the load break. This contact is made before the circuit within the fuse cutout is broken as the distance that the cap on the end of the fuse tube travels between the contact brackets 15 is greater than the distance between the movable contact 6 and the curved surfaces 26a of the said shunt horn 26.

Since the current is already shunted around the air gap between the upper stationary terminal and the upper movable contact of the cutout before breaking the Contact between the fuse 5 and the contact brackets 15 there is no spark over within the cutout housing as the door 3 of the fuse cutout is being opened. The current continues to travel through the fuse so that the line is protected from overload at all times.

As the door 3 is opened farther the movable contact 6 trips the latch extension 2%, moving the latch 29 out of the notch 25 which releases the suspended assembly within the load break housing. The pressure spring Z2 pushes the plastic plunger 2l to the right and the spacer 20, conductors 19 and 24 ahead of it until the parts of the load break are in the position shown in Fig. 2. The U- shaped spring El assures a conductive path from the inner conductors 19 and 24 through the ferrule Z7 to the said shunt horn 26 to prevent spark over when the latch 29 is being tripped.

After the tripping action has taken place the leaf spring 3i) returns the latch 29 to its former position so that it will stop the arcing contact 20 from moving farther to the-right. Within the load break housing the circuit has been opened by the movement of the plastic plunger tube 21 into proximity with the fibre housing 16. The pressure created between the plastic and fibre being greater than the outside pressure it will tend to push outwardly through the space 32 between the inside tubes and the ferrule 27. This pressure of gases outwardly will extinguish any arc that might occur when the circuit is opened within the load break. Thus, it can be seen that an air gap has been created within the load break housing by moving non-conductive members into the circuit and moving the conductive members out of the circuit.

After the repair work has been done or the inspection made, the fuse cutout door can be reclosed and the circuit resumed through the fuse cutout. The load break can be reused after the rod 19 with attached plastic plunger tube 21 is pushed back against the spring 22 into the fibre tubular housing 16 and tubular member 11 respectively, to latched position as shown in Fig. l. Nothing is damaged in the load break by using it. It can be put into operation many times.

My load break can be mounted on top of the fuse cutout box as shown in Fig. 3 or it can be mounted on the side of the box as shown in Fig. 4. In both arrangements the mounting conductor is connected to the terminal that enters the fuse box. The conductor strip 6 can extend through the cutout door either at the top or at the side depending upon Where the load break is placed.

With a slight change in the shape of a fuse cutout door, it is also possible to place this load break within the fuse box. The same procedure would take place. As the cutout door is opened, the movable contact would shunt the current around the air gap between the upper stationary terminal and the upper movable terminal of said cutout through the load break before the regular circuit was interrupted. lt is also conceivable that my load break could be adapted to other forms of circuit interrupters.

Thus, my load break provides an effective and inexpensive device for momentarily shunting current around an air gap produced between a stationary contact and a movable contact so that a circuit interrupter can be opened without dangerous arcing.

I claim:

l. A load break device in combination with a cutout, said cutout including a fixed terminal, a pivotally mounted fuse tube releasably electrically connected thereto, and a movable Contact connected to said fuse tube and swingable therewith, said load break device comprising a circuit interrupter biased to open circuit position and normally electrically connected to said fixed terminal, and latch means normally restraining said circuit interrupter connected to said fixed terminal in closed circuit position, whereupon said movable contact may be swung to a rst position directly connecting said fuse with said fixed terminal and indirectly with said fixed terminal through said load break device to a second position connecting said fuse and load break device in electrical series relation, and to a third position whereby said latch means is released to open the electrical circuit within said load break device.

2. A load break device in combination with a cutout, said cutout including a fixed terminal, a fuse tube releasably electrically connected to said iixed terminal, support means pivotally carrying and slidably embracing said fuse tube, and a movable Contact in electrical relation to said fuse tube and swingable and slidable therewith, said load break device comprising a circuit interrupter biased to open circuit position and normally electrically connected to said iixed terminal, and latch means normally restraining said circuit interrupter connected to said fixed terminal in closed circuit position, said latch means extending into aligned spaced relation with said movable contact, where upon said movable contact may move to a first position directly connecting said fuse with said fixed terminal and indirectly with said fixed terminal through said load break device and said latch means', to a second position connecting said fuse and load break device in electrical series relation, and to a third position whereby said latch means is released to open the electrical circuit within said load break device.

3. A load break device for an enclosed fuse cutout, said fuse cutout characterized by an insulating housing enclosing a fuse receiving fixed terminal and a fuse tube carried by a pivotally mounted door for swinging movement with respect to said fixed terminal, said load break device comprising a tubular member having circuit interrupting means therein normally restrained in circuit closed position, a support member electrically connecting said fixed terminal and said tubular member, a spring biased rod means projecting from said tubular member for actuating said circuit interrupter, latch means carried by said tubular member and engaged with said rod means for maintaining said circuit interrupting means in circuit closed position, a movable contact electrically connected to said fuse tube and pivotable therewith into electrical contact with said latch means prior to disconnection of the fuse tube from said fixed terminal, whereafter continued pivotal movement of said movable contact will trip said latch releasing said circuit interrupter to circuit open position.

4. A load break device for a fuse cutout, said cutout characterized by a fixed terminal and a fuse tube swingably receivable by said terminal, said load break device comprising a conductive tubular member closed at one end and a non-conductive gas evolving tubular member coaxially adjacent thereto, a support member electrically connecting said fixed terminal and said conductive tubular member, a plunger slidable axially within said tubular members, spring means within said tube biasing said plunger toward said gas evolving tube, an arcing contact carried by and slidable with said plunger, resilient arms normally connecting said conductive tubular member to said arcing Contact, an arcing ring adjacent and connected to said resilient arms, a conductor rod having one end attached to said arcing contact and another end projecting from said gas evolving tubular member and including a manual reset head portion, latch means carried by said gas evolving tube normally engaging said rod, a movable contact connected to said fuse tube and swingable therewith to sliding contact relation with said latch means, whereby swinging said movable contact will divert an 5 electric current through said load break device into series relation with said fuse tube.

5. A load break device for a fuse cutout, said cutout having a fixed terminal and a fuse tube swingably receivable thereby, said load break device comprising a conductive tubular member and a non-conductive tubular member coaxially adjacent thereto, a support member electrically connected to said xed terminal and embracing said conductive tubular member, a spring biased circuit interrupting plunger slidable within said tubular members, a conducting rod connected to said plunger and projecting coaxially from said conductive tubular member, a ferrule on said non-conductive tube circumjacent said rod, a substantially U-shaped spring aflixed to said ferrule and biasing said rod thereagainst, latch means connected to said ferrule normally restraining said plunger in circuit Closed position, a movable contact swingable with said fuse tube into sliding contact relation with said latch means prior to separating from said fixed terminal thereby diverting an electric current through said load break device, whereafter said plunger may be tripped by said movable contact to open the electric circuit Within said load break device.

References Cited in the le of this patent UNITED STATES PATENTS 1,393,344 Conrad Oct. 11, 1921 2,200,122 Rawlins May 7, 1940 2,424,126 Smith, Jr July 15, 1947 2,434,315 Froland Jan. 13, 1948

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