US2734966A - Circuit interrupter - Google Patents

Description

Feb. 14, 1956 H. P. SCHNEIDER CIRCUIT INTERRUPTER 3 Sheets-Sheet 1 Filed NOV. 20, 1952 INVENTOR.

1956 H. P. SCHNEIDER CIRCUIT INTERRUPTER 3 SheetsSheet 2 Filed Nov. 20, 1952 INVENTOR.

Feb. 14, 1956 P, scHNElDER 2,734,966

' CIRCUIT INTERRUPTER Filed Nov. 20, 1952 3 Sheets-Sheet 3 INVENTOR. Hans hnfiiole flllorn/ 7 United States Patent CIRCUIT IN TERRUPTER Hans P. Schneider, Milwaukee, Wis., assignor to McGraw Electric Company, Milwaukee, W1s., a corporation of Delaware Application November 20, 1952, Serial No. 321,545

16 Claims. (Cl. 200-114) This invention relates to a loadbreak to be used on an enclosed fuse cutout for electrical apparatus.

There are numerous occasions when it is necessary to inspect theelectrical lines or-to do some repair work on the lines and, of course, to do so requiresinterrupting the current. When a fuse cutout is opened an air gap is provided but during the process of opening a fuse cutout manually, one is apt to draw a large are. This is undesirable for several reasons. It is dangerous to the lineman and it is apt to burn the contact points which would impairthe effectivness of the cutout.

In my copending patent application Serial No. 274,128, filed February 29, 1952, now Patent No. 2,709,736, dated May 31, 1955, I provide a loadbreak device mounted on the outside of an enclosed fuse cutout. This invention is a further development of the loadbreak idea disclosed in said patent.

The object of this invention is to provide a loadbreak incorporated in a fuse cutout door that can be installed on a standard fuse cutout.

Another object of this invention is to provide a means of opening the door of a fuse cutout without drawing an arc.

A further object of this invention is'to shunt the current in a fuse cutout while the door of the cutout is being opened.

Another object of this invention is to provide a loadbreak 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 flash-over.

And another object of this invention is to provide a latching device in the loadbreak door that prevents reclosing of the door until the loadbreak is reset.

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

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

Fig. 1 is a sectional view of myloadbreak incorporated in the door of an enclosed fuse cutout showing the door in closed position.

Fig. 2 is similar toFig. l but with the door in open position.

Fig. 3 is a sectional view taken substantially on the line 3-3 of Fig. 1.

Fig. 4 is a fragmentary view showing the latch closed around the projecting stud of the conductor rod.

Fig. 5 is a fragmentary view showing the movement of the latch as the loadbreak door is being opened.

Fig. 6 is a fragmentary view showing the latch being spread apart by the upward movement of the stud.

Fig. 7 is a side vew of the latch taken approximately on the line 77 of Fig. 5.

Like reference figures indicate like parts throughout.

Referring to Figs. 1 and 2, I indicate a standard fuse cutout box 1 consisting of a porcelain housing 2 with an is a plug 32 forming a top closure.

upper terminal 3 and a lower terminal 4. A hook member 5 is located at the lower portion of the box. Attached to the upper terminal 3 is a conductive pressure spring 6. Mounted on the upper portion of the conductive pressure spring 6 is a secondary contact button 7.

My loadbreak device is built entirely in a fuse cutout door 8 and can be fitted onto the standard fuse cutout box 1 by the hook means 5. The door has a standard holding member 9 to hold a fuse tube 10 so that when the door is closed the conductor cap 10a of the fuse tube 10 fits under tension beneath the pressure spring 6.

The fuse cutout door 8 consists of a porcelain housing 11 with an eyelet 12 providing the means for opening the door with a switch stick. In the upper interior of the door housing 11 above the eyelet 12 are two recesses 13 and 13a to receive the leg ends of a U-shaped movable contact member 14. This movable contact member 14 slides in two tubular positioning holders 15 and 16. The holder 16 has a greater length and diameter than the holder 15 to provide space for a spring 17 to operate and actuate the movable contact member 14. The spring 17 surrounds the leg 14a of the movable contact 14 in the area between a slidable collar 18 on the leg 14a and the recess 13a. One end of this spring 17 is located in the recess 13a and causes an outward thrust on the movable contact 14 holding it tightly against theupper terminal button 7 at all times even as the door is being opened. On the opposite side of the collar 18 from the spring 17 is a washer 19 and a pin 60 which locate the collar 18 flush with the outer face of the holder 16 when the movable contact 14 is thrust inwardly. Near the end of-leg 14b is a protruding peg 61 which prevents further outward movement of the movable contact 14 beyond the notched portion 62 in the holder 15.

Extending substantially coextensive with the interior of the fuse cutout door 8 is the main body of the loadbreak device 21 It is mounted upon an inner shoulder extension 21 of the porcelain door 11 with a metal collar 22 between the shoulder 21 and the loadbreak device 20. The loadbreak is also held in mid-section by means of a welded section 23 to an abutting piece 24. A connecting plate 25, shown in Fig. 3 attaches the holders 15 and 16 to the upper part of the loadbreak body 20. e

The upper portion of the loadbreak body 20 is composed of a tubular metal housing 26 with a slot 27 extending down one side. The slot is shown in views 2, 4, 5, and 6. The lower portion of the loadbreak body 20 is a tubular fibre housing 28. The two tubular housings are held together by a clamping collar 29. Two metal rings 30 and 31 are within the collar 29 above the fibre tube'28.

At the upper end of the conductive tubular housing 26 Extending downwardly from the plug 32. is a guide rod 33 around which a tension spring 34 extends.

A movable portion of the loadbreak extends within the precedingly described housing. It consists of a fibre tube 35 with a seating portion 36 within, to which the lower end of the spring 34 is anchored. The upper end of the fibre tube 35 is enclosed by a collar 37. A stud 38 exends from the collar 37 transversely outwardly through the slot 27 in the tubular housing 26. This stud 38 rests on the movable contact leg 1412 when the loadbreak fuse tube is in cocked position, and when the stud 38 is released by movement of the movable contact 14 it drops downwardly in the slot 27.

At the lower end of the fibre tube 35 is a steel arcing ring 39 attached by threaded screw means 40 into the bottom of the fibre tube 35. A second steel ring 41 is inserted around the screw 40 between the fibre tube 35 and the arcing ring 39. Extending downwardly from the arcing ring 39 is a conductor rod 42. A stainless steel spring 43 of slightly conical shape surrounds the lower end of the conductor rod 42. This spring 43 is anchored v at thebottom of the fibre tube 28 between it and a metal A in Figs. 1 and 2. These pins are welded on opposite sides of the loadbreak housing26 and on opposite sides of the movable contact 14. The latching device 46 and its operation is shown in Figs. 4, 5, 6, and 7. It consists of two latches, a lower actuating latch 47 and an upper latch 48 which controls the actuating latch. The latches have protruding portions 49 and 50 around which the ends of a torsion spring 51 are hooked. The spring 51 acts to pull the upper and lower latches together in locking position.

In Fig. 4, the upper and lower latches are locked around the stud 38 of the movable inner portion of the loadbreak and hold the stud in this cocked position while the door is being closed and the movable contact 14 moves to its inner position whereby the leg 14b of the movable contact 14 supports the stud in cocked position.

'The dash dot lines of Fig. 4 indicated the position to which the lower latch 47 is pushed by the inward movement of the leg 14b. The lower latch 47 is pushed aside so as not to interfere with the downward movement of the stud 38 when the loadbreak is operated.

When the fuse cutout door is opened and the movable contact 14 moves outwardly under the pressure of the spring 17, the leg 14b moves to the position shown in Fig. 5. This releases the stud 38 allowing it to drop and the upper latch 48 to drop downwardly into the space left by the movable contact leg 14b. The stud 38 being released allows the inner movable fibre fuse tube to drop down in the loadbreak housing. The downward movement of the stud 38 holds the lower latch 47 aside until its passes that portion 47a of the lower latch which is in the same plane as the stud. In Fig. 7 it can be seen that the lower latch 47 is offset in its lower portion so as not to interfere with the further downward travel of the stud 38. After the stud has passed the lower latch 47,

- the latch is free to snap back against the upper latch 48 under pressure from the spring 51.

Fig. 6 illustrates the re-cocking process. As the movable inner portion of the loadbreak is pushed upwardly by means of the conductor rod 42 of Fig. 1, the stud 38 pushes aside the lower latch 47 in that upper area 47a which it contacts. As the stud 38 is moved farther in the upward direction it lifts the upper latch 48 and moves into the position shown in Fig. 4. The lower latch 47 snaps back to the under side of the stud and holds it there while the fuse cutout door is being closed and the movable contact leg 14b is thrust back into its inner position under the stud 38. Because the upper latch 48 drops into the space occupied by the movable contact leg 14b when the loadbreak is in an. uncooked position, it prevents the movable contact 14 from being thrust inwardly which in turn prevents the closing of the fuse cutout door when the loadbreak is in an uncooked or unset position.

A front shelf 52 of insulating material extends across the inner side of the fuse cutout door and prevents ex- I ploding gases from escaping in the direction of the upper terminal. In this shelf 52 is a conductive contact button 53 which presses against the conductor cap of the fuse 10 because of spring pressure means 54. An insulated wire 55 embedded in the porcelain of the shelf 52 forms a conductive path from the conductor collar 22 to the contact button 53, thus completing the auxiliary circuit.

The use and operation of my invention are as follows:

This fuse cutout with a loadbreak built in the door provides a means of opening the circuit without creating a dangerous arc. The main current path is from the upper terminal 3 through spring 6 and the fuse tube 10 to the lower terminal 4. The loadbreak provides an auxiliary path for the current. Its route is from the upper terminal 3 to the movable contact 14 at the contact button 7. From the movable contact legs 14 the current flows down the conductive tubular housing 26 to the collar 29 and conductor ring 30 to the arcing ring 39 and from there down the conductor rod 42. The spring 43, the conductor plate 56 at the bottom of the'loadbreak and the. conductor collar 22 carry the current to an insulated wire 55 which extends to the metal contact button 53 pressed by spring tension means 54 against the conductor cap of the fuse 10. The auxiliary current path then follows the same path as the main current.

With two current paths one path can be interrupted without causing an arc. Fig. 2 shows the door in open position. As the door 8 is opened the movable contact 14 is thrust outwardly by the spring 17 sothat it continues to maintain a firm contact against the button 7 of the upper terminal. During the opening of the door the'conductor cap 10a of the fuse 10 is disengaged from the spring 6 before the movable contact 14 is removed from under the stud 38. This prevents arcing between the fuse 10 and the spring 6 as the current is still flowing through the loadbreak when the fuse breaks contact.

When the door reaches the angle of opening which removes the movable contact 14b from under the stud 38, the inner movable section of the loadbreak is released and drops downward in the tubular conductive housing 26 and the lower tubular fibre housing 28 to the position shown in Fig. 2. As the stud 38 and the collar 37 with the fibre tubular member 35 move downwardly, the arcing ring 39 moves out of conductive proximity with the conductive housing 26, and the fibre member 35, a non-conductor moves into its place.

By changing the juxtaposition of conductive material and non-conductive material, the auxiliary current path is interrupted within the loadbreak where arcing is harmless. The two fibre tubes 35 and 28, concentric to each other, break the current flow and extinguish any flashover that might occur. The gases are expelled out of the lower opening of the fibre tubes.

After inspection or repairs are made the door can be closed again. The double latching arrangement prevents accidental closing of the door before the loadbreak has eben re-cocked. The upper latch 48 prevents thrusting the movable contact 14 into closed position until the loadbreak has been reset which is indicated by the stud 38 moving the lower latch 47 aside and lifting the upper latch 48 so as to fit in locked position between the two latches.

My invention provides a loadbreak device installed in a door that can be inserted in a standard fuse cutout. It provides a means of opening an electrical circuit without arcing. The current flow is broken in a confined area of fibre tube where it can do no harm and where the flash is quickly extinguished by the inherent properties of the fibre. And this loadbreak has a safety latch which prevents the door from being closed before the loadbreak is re-cocked to operating position. With this loadbreak, it is possible to close off a section of the electrical lines where repairs or inspection are needed and to do it without the risk of injuring a lineman or burning the con tacts.

I claim:

1. A switch adapted to be opened under load comprising an insulating housing including a door, two terminal members fixedly spaced from each other within the housing, switch means for connecting and disconnecting said terminal members by movement to closed and open position respectively, insulating door means for moving said switch means, an auxiliary circuit normally connected from one of said fixed terminals to said switch means within said housing, the upper contact of said auxiliary circuit having a spring biasing said contact against the upper of the said two fixed terminal members while said switch means is being operated, maintaining said contact between the upper movable contact and the upper of the said two fixed terminals after said switch means has disconnected said two terminals, the said auxiliary circuit comprising conductive members normally in series and are extinguishing nonconductive members, latch means for separating said conductive members and inserting said arc extinguishing non-conductive members in series with said switch means to break the electrical path of said auxiliary circuit, and means for replacing the conductive members in series.

2. In a circuit interrupter including a housing having a door, a pair of spaced upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to a movable auxiliary circuit within said loadbreak, said upper movable contact being of suflicient length to maintain the movable auxiliary circuit through the loadbreak in closed position while the door of said circuit interrupter is being opened and until after the fuse that bridges said terminals has been removed from etween said terminals, said upper movable contact in open door position releasing the said movable auxiliary circuit within said loadbreak, said movable auxiliary circuit comprising coaxially disposed conductive and nonconductive tubular members adjacent each other at their ends, a conductive contact collar normally restrained in contact relation to said conductive tubular member and slidable to contact relation with said non-conductive tubular member when said door is in open position.

3. In a circuit interrupter including a housing having a door, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non-conductive materials forming a releasable auxiliary circuit when in closed position and breaking said circuit when in open position, said non-conductive materials having arc extinguishing characteristics, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the releasable auxiliary circuit within said loadbreak, said upper movable contact being of sufiicient length to maintain the releasable auxiliary circuit while the door of said circuit interrupter is being opened, said releasable auxiliary circuit being maintained until after the fuse has been removed from between said terminals, said upper movable contact when in open door position releasing the said releasable auxiliary circuit thus separating the conductive material within said loadbreak and inserting the non-conductive materials to break the auxiliary circuit and extinguish the are thereby.

4. In a circuit interrupter including a housing having a door, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non-conductive materials forming a releasable auxiliary circuit when in closed position and breaking said circuit when in open position,

said non-conductive materials having arc extinguishing characteristics, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminals while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the releasable auxiliary circuit within said loadbreak, said upper movable contact being of sufiicient length to maintain the releasable auxiliary circuit while the door of said circuit interrupter is being opened, said releasable auxiliary circuit being maintained until after the fuse has been removed from between said terminals, said upper movable contact when in open door position releasing the said releasable auxiliary circuit thus separating the conductive material within said loadbreak and inserting the non-conductive materials to break the auxiliary circuit and extinguish the are thereby, a latching means releasably engageable with said upper movable contact for preventing the closing of said door while the loadbreak is in open circuit position and for positioning and holding said auxiliary circuit when said circuit is returned to closed position while the door is being closed.

5. In combination with an insulating housing including a door, an enclosed fuse cutout comprising upper and lower terminals with a removable fuse extending between them and attached to the door of said cutout, a loadbreak enclosed in the door of said cutout, said loadbreak having a conductive circuit and an arc extinguishing non-conductive circuit position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed position forming a maintaining means for said conductive circuit position of said loadbreak, said upper movable contact while said door is being opened continuing to maintain the conductive circuit position of said loadbreak until after the fuse that bridges said terminals has been disengaged from said upper terminal, said upper movable contact in open door position releasing the conductive circuit in the loadbreak and establishing the arc extinguishing nonconductive circuit position, said are extinguishing nonconductive circuit position breaking the electrical circuit and extinguishing arcing within the loadbreak.

6. In combination with an insulating housing including a door, an enclosed fuse cutout comprising upper and lower terminals with a removable fuse extending between them and attached to the door of said cutout, a loadbreak enclosed in the door of said cutout, said loadbreak having a conductive circuit and an arc extinguishing nonconductive circuit position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movabie contact when in closed position forming a maintaining means for said conductive .circuit position of said loadbreak, said upper movable contact while said door is being opened continuing to maintain the conductive circuit position of said loadbreak until after the fuse that bridges said terminals has been disengaged from said upper terminal, said upper movable contact in open door position releasing the conductive circuit in the loadbreak and establishing the arc extinguishing non-conductive circuit position, said are extinguishing non-conductive circuit position breaking the electrical circuit and extinguishing arcing within the loadbreak, a latching means for preventing the closing of said cutout door while the loadbreak is in nonconductive circuit position and for positioning and holding said conductive circuit position of said loadbreak while said cutout door is being closed and until said upper movable contact resumes its position of maintaining the conductive circuit position of said loadbreak.

7. In combination with an insulating housing including a door, an enclosed fuse cutout comprising upper and lower terminals with a removable fuse extending between them and attached to the door of said cutout, a loadbreak enclosedin the door of said cutout, said loadbreak having a closed circuit and an open circuit position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a bridges said terminals has been removed from between said terminals, said upper movable contact in open door position releasing the loadbreak means for movement to open-circuit position thereof, and said loadbreak means extinguishing the are within the same while moving to open circuit position.

8. In combination with an insulating housing including a door, an enclosed fuse cutout comprising upper and lower terminals with a removable fuse extending between them and attached to the door of said cutout, a loadbreak enclosed in the door of said cutout, said loadbreak having a closed circuit and an open circuit position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a maintaining means for said closed circuit position of said loadbreak, said upper movable contact while said door is being opened continuing to maintain the closed circuit position of said loadbreak until after the fuse that bridges said terminals has been removed from between said terminals, said upper movable contact in open door position releasing the loadbreak means for movement to open circuit position thereof, and said loadbreak means extinguishing the arc within the same while moving to open circuit position, a latching means for preventing the closing of said cutout door while the loadbreak is in open circuit position and for positioning and holding said closed circuit position of said loadbreak while said cutout door is being closed and until said upper movable 'contact resumes its position of maintaining the closed circuit position of said loadbreak.

9. In a housed circuit interrupter with a hinged door, a pair of spaced terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak having a conductive series and a non-conductive series, said non-conductive series including a fibre insulating tube, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with one of the said terminals while the door is being opened, said upper movable contact when in closed door position maintaining the said conductive series within said loadbreak, said upper movable contact while said door is being opened continuing to maintain the conductive series through the loadbreak until after the fuse that bridges said terminals has been disengaged from one of said terminals, said upper movable contact in open door position releasing the said conductive series circuit within said loadbreak allowing the non-conductive series to break the circuit, and the fibre insulating tube toextinguish the are.

10, In a housed circuit interrupter, a door on said circuit interrupter, a pair of spaced terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak having a conductive position and a non-conductive position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with one of the said terminals while the door is being opened, said upper movable contact when in closed door position maintaining the said conductive position within said loadbreak, said upper movable contact while said door is being opened continuing to, maintain theconductive position through the loadbreak until after the fuse that bridges said terminals has i 8 been disengaged from one of said terminals, said upper movable contact in open door position releasing the said conductive position by the circuit within said loadbreak allowing the non-conductive position to break the circuit during movement thereto.

ll. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising conductive and non-conductive materials, the conductive materials in series forming a closed circuit in the loadbreak and the non-conductive materials in series forming an open circuit in the loadbreak, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the said conductive materials in series forming an auxiliary circuit within said loadbreak, said upper movable contact being of sufiicient length to maintain the auxiliary circuit through the loadbreak while the door of said circuit interrupter is being opened, said auxiliary circuit being maintained until after the fuse that bridges said terminals has been disengaged from said upper terminal, said upper movable contact when in open door position releasing the said conductive materials in series within said loadbreak allowing the non-conductive materials in series to break said auxiliary circuit and to extinguish the are.

12. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising conductive and non-conductive materials, the conductive materials in series forming a closed circuit in the loadbreak and the nonconductive materials in series forming an open circuit in the loadbreak, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the said conductive materials in series forming an auxiliary circuit within said loadbreak, said upper movable contact being of sufficient length to maintain the auxiliary circuit through the loadbreak while the door of said circuit interrupter is being opened, said auxiliary circuit being maintained until after the fuse that bridges said terminals has been disengaged from said upper terminal, said upper movable contact when in open door position releasing the said conductive materials in series within said loadbreak allowing the non-conductive materials in series to break said auxiliary circuit and to extinguish the are, a latching means releasably engageable with said upper movable contact for preventing the closing of said door while the auxiliary circuit is in open position and for positioning and holding said auxiliary circuit in closed position while the door is being closed.

13. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a remov able fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non'conductive materials forming a movable auxiliary circuit when in closed position and breaking said circuit when in open position, plunger means within said series of conductive and nonconductive materials for maintaining said closed circuit, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper sufiicient length to maintain the auxiliary circuit while the door of said circuit interrupter is being opened, said auxiliary circuit being maintained until after the fuse has been disengaged from said upper terminal, said upper movable contact when in open door position releasing said plunger means to drop down and separate the conductive material within said loadbreak to break the circuit.

14. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non-conductive materials forming a movable auxiliary circuit when in closed position and breaking said circuit when in open position, plunger means within said series of conductive and non-conductive materials for maintaining said closed circuit, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper ter minal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the movable auxiliary circuit within said loadbreak, said upper movable contact being of sufiicient length to maintain the auxiliary circuit while the door of said circuit interrupter is being opened, said auxiliary circuit being maintained until after the fuse has been disengaged from said upper terminal, said upper movable contact when in open door position releasing said plunger means to drop down and separate the conductive material within said loadbreak to break the circuit, a latching means releasably engageable with said upper movable contact for preventing the closing of said door while the auxiliary circuit is in broken position and for positioning and holding said auxiliary circuit after said plunger has returned said auxiliary circuit to closed position, said latching means maintaining said auxiliary circuit in closed position While the door is being closed.

15. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non-conductive materials forming a movable auxiliary circuit when in closed door position and breaking said circuit when in open door position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the movable auxiliary circuit within said loadbreak, said upper movable contact being of sufficient length to maintain the auxiliary circuit while the door of said circuit interrupter is being opened, said auxiliary circuit being maintained until after the fuse has been disengaged from said upper terminal, said upper movable contact when in open door position separating the conductive material within said loadbreak to break the circuit.

16. In a housed circuit interrupter, a door on said circuit interrupter, upper and lower terminals, a removable fuse for bridging said terminals attached to the door of said circuit interrupter, a loadbreak enclosed in the door of said circuit interrupter, said loadbreak comprising a series of conductive and non-conductive materials forming a movable auxiliary circuit when in closed door position and breaking said circuit when in open door position, said loadbreak having an upper movable contact with spring pressure means to hold it in contact with the said upper terminal while the door is being opened, said upper movable contact when in closed door position forming a restraining means to the movable auxiliary circuit within said loadbreak, said upper movable contact being of suflicient length to maintain the auxiliary circuit while the door of said interrupter is being opened, said auxiliary circuit being maintained until after the fuse has been disengaged from said upper terminal, said upper movable contact when in open door position separating the conductive material within said loadbreak to break the circuit, a latching means releasably engageable with said upper movable contact for preventing the closing of said door while the auxiliary circuit is in broken position and for positioning and holding said auxiliary circuit in closed position while the said door is being closed.

References Cited in the file of this patent UNITED STATES PATENTS 1,393,344 Conrad Oct. 11, 1921 2,337,889 Harlow et a1. Dec. 28, 1943 2,344,113 Schultz Mar. 14, 1944 2,509,892 Steinmayer et al. May 30, 1950

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