US1130485A

US1130485A - Electric fuse.

Info

Publication number: US1130485A
Application number: US76518413A
Authority: US
Inventors: Charles W Davis
Original assignee: STANDARD UNDERGROUND CABLE Co
Current assignee: STANDARD UNDERGROUND CABLE Co
Priority date: 1913-05-03
Filing date: 1913-05-03
Publication date: 1915-03-02
Anticipated expiration: 1932-03-02

Description

C. W. DAVIS; ELECTRIC FUSE.

APPLICATION FILED MAY 3,1913.

1,1 30,485, Patented Mar. 2, 1915.

WITN ESSESI INVENTOR 'UNITED STATES PATENT OFFICE.

CHARLES W. DAVIS, F EDGEWORTH, PENNSYLVANIA, ASSIGNOR T0 STANDARD UNDERGROUND CABLE COMPANY, OF FITTSBURGH, PENNSYLVANIA, A CORPO- RATION OF PENNSYLVANIA.

ELECTRIC FUSE.

To all whom it may concern:

- Be it known that 1, CHARLES W. DAVIS, residing at Edgeworth, in the county of Allegheny and State of lennsylvania, a citizen of the United States, have invented or discovered a certain new and useful Improvement in Electric Fuses, of which improvemen-t the following is a specification.

My invention relates to electric fuses or cut-outs adapted to interrupt an electric circuit upon the passage therethrough of abnormal and dangerous currents, and has particularly to do with fuses for high tension currents.

It" is well understood that electric fuses are designed or rated so as to break the cir- I cuit, in which they are placed, when the cur rent carried thereby reaches or exceeds a predetermined strength] The conditions,.

under which such fuses become effective, vary' throughout a wide range. First, the

current carried by the circuit may gradually rise until the predeterminedfusion point of the fuse is reached, the blowing.

thereof under such conditionbeing usuallyattended by a relatively small explosion and a correspondingly decreased liabilityof an are being established. Also, when the rise in the current is gradual, the. fusible element heats up slowly, and during such heating period the circuit will remain closed and.

will be subjected to a current of greater strength than it is intended to carry. In

the second'place, a short circuit of substantially any strength in excess of the-fuse rating may almost instantaneously traverse the circuit, causing the fuse to blow with a violent explosion, and very materially increasing the liability of a continued arc, being established.

It is the object of my present invention to provide a fuse or cut-out, whereby the rapidity and extent or intensity of the circuits interruption will vary according to the character of the current traversing the circuit and causing such interruption.

In the accompanying drawing I have illustrated in vertical section a single embodiment of my invention. s

Having reference first to the constructio of the fuse illustrated herein, and subsequently to its operation under the varying conditions of service, the complete structure is placed in a fuse box 1, through the Specification of LettersPat-ent.

Patented Mar. 2, 1915;

\ a iieationfiieana s, 191a Seria1No.765,184.

contactor consisting preferably of a tube 7- having a plurality of spring arms at its lower end, adapted to electrically engage or contact with the inner surface of said sleeve 4. The upper end of the fuse casing is closed by meansof a suitable plug 8, provided with a binding post 9; and a fuse strip, comprising a low fusion portion 10 and adjoining

higher fusion portions

11 and 12,'is placed in the upper portion of the casing, the portion 11 being electrically connected to the binding post 9, and the portion 12 to the contactor 7 by means of a suitable flexible conductor 13,, which preferably eX- te'nds' through and is secured to a suitable pressure-resisting movable abutment 20. The casing 5 is loosely mounted for vertical movement in a tube 14, which is secured to a transversely extending support 21 of insulating material, which in turn is supported. by rods 22. The arrangement is such that gases, generated upon the blowing of the fusible element 10,-will exert their expansive forces longitudinally of the casing 5 and cause it. to move vertically, carrying with it the contactor 7 thereby disengaging it from the contactor a. A second means is also provided for moving the fuse. casing to effect a disengagement of the contactors l and 7, such means being effective upon the flowing of an abnormal current through the circuit, but independent of the explosive action of the fuse strip. As illustrated herein,"surh means consists of an electromagnetic coil and a core or plunger adapted to engage the fuse casing 5, preferably striking it a hammer blow as it is drawn into the magnetic field of the coil, the arrangement being such that the plunger will not be caused to move until the current flowing through the fuse has exceeded the fuse rating.

Referring again to the drawing, the plunger is, in this embodiment of my invention, a tube 15 loosely surrounding the fuse casing 5 and vertically movable with relation thereto, the lower end of the tube resting upon the support-21. A plunger-engaging abutment 16 projects from the side of the casing 5 in the path of movement of the plunger and above the upper end thereof, the arrangement being such that the movement of .merged in a body of arc-dampening liquid,

such as oil or carbon tetra-chlorid. When the fuse box L is filled \with such a liquid to a point above the level of the top of the casing 5,

suitable holes

18 and 19 may be placed in the lower and upper ends, respectively, of such casing so. that the find may circulate therethrough and thus cool the fusible element .10. If, however, it is desirable to have the fusible element 10 unsurrounded by such liquid the upper casing holesmay be placed below the fusible element 10 as indicated at 19 in which event a fuse-containing pocket will be formed 1n the upper portion of the casing 5. Such pocket may be filled with an inert granular material, such as slaked lime or magnesia, or the pocket may be simply an air-pocket, the air pressure varying according to the level of the liquid within the fuse box.

When, inthe operation of the fuse, the current carried by the circuit gradually rises to and above the rated capacity of the fusible element 10, the plunger 15, being.

drawn within the coil 17, strikes the casing abutment 16 and lifts the casing 5, thus disengaging the contactors 4 and 7. As will be readily seen, theadvantageof such an arrangement is that the circuit will be effectually opened even though the are formed by the blowing of. the fuse should hold on, in which event theexpansion of the gases will expel the relatively cool liquid from the lower end -of the. casing 5 and between the two contactors 4 and 7,

v thus more effectually quenching the are at this point Also, thegap between the free ends of the

high fusion portions

11 and 12 will be widened. k Incase the circuit is short-circuited bya current of materially greater strength than the rated capacity of the fusible element 10, such element will be fused almost instantaneously. The plunger will, in this event, impart a hammer blow to the casing 5, thus overcoming the initial frictional resistance "betweenthe contactors 4 and 7, which contactors will be separated both by the action of the electro-magnet and by the explosive forces of the fuse.

within said casing,

I claim as my invention: 1. In an electric fuse, the combination of a fuse box containing a bodyof arc-dampening liquid, a. pairof contactors submerged in said liquid and movable to and from engagement with each other, a casing secured to one of said contactors, afuse strip within the casing, and means for ap-.

plying the explosive force of said fuse when blown to separate said contactors and to force a stream of arc-dampening liquid between them when separated.

2. In an electric fuse, the combination of a fuse box containing a body of arcdampenlng liquid, a fixed contactor submerged in the liquid, a fuse casing provided with a contactor movable to andfrom engagement with the first named contactor and adapted to contain a portion of the liquid within the fuse box, an expulsion opening in said casing adjacent to thepoint of engagement of said'contactors, a fuse strip within said casing, and means for applying the explosive force of said fuse strip when blown to move the contactor borne by the casing from its engagement with said fixed contactor and to expel the liquid from the fuse casing through said opening and between the separated contactors.

3. In an electric fuse, the combination of a contactor, a movable fuse casing provided with a contactor adapted to electrically engage said first-named contactor, a fuse strip and means efiective upon the passage of an abnormal current through said fuse strip to engage and move said casing, therebydisengaging said contactors.

4. In an electric fuse, the combination of a contactor, a movablefuse casing provided with a contactor adapted to electrically engage said first-named contactor, a fuse strip within said casing, an electro-magnet havmg its coil in circuit with said fuse and a movable plunger in the magnetic field of said coil and means for applying the movmg force of said plunger to said casing upon the passage of an abnormal current through said fuse.

5. In an electric fuse, the combination of .a fuse-box containing a body of arc-dampening liquid, a contactor submerged in said llquld, a movable fuse casing provided with anexpulsion opening beneath the surface of said liquid, a contactor secured to and a fuse strip within said casing, and means effective upon the passage of an abnormal current through said fuse strip to move said casing for disengaging said contactors, and means for applying the expansive forces of the gases of fusion generated by the blowing of said fuse strip to expel the liq'uidfrom said casing and between said disengaged contactors.

6. In an electric fuse, the combination of a fuse box containing a body of arc-dam-- a fuse casing provided with an expulsion pening liquid, a pair of engaging but separable oontactors submerged in said liquid,

opening adjacent to said contactors and below the level of the liquid Within said box, a fuse strip Within said casing, means effective upon the passage of an abnormal current through said fuse to disengage said contactors, and means for applying the ex-.

pensive forces of the gases of fusion generated by the blowing of said fuse strip to expel the liquid from said casing and be: tween said disengaged contactors.

7. in an electric fuse, the combination of a fuse box containing a body of arc-dampening liquid, a fixed contactor in said box, a vertically-disposed and vertically-movable fuse casing closed at its upper end and open casing adjacent to its open lower end and adapted to electrically engage said firstnamed contactor, a fuse strip within the upper portion of said casing, an electromagnet haying itscoil in circuit with said strip, a movable plunger in the magnetic field of said coil, and means for applying the moving force of said plunger to dislodge said casing upon the passage of an abnormal current through said fuse strip.

In testimony whereof I have hereunto set my hand. CHARLES W. DAVIS.

Witnesses:

R. W, WHITE, FRANGIS J. TomAssoN.

at its lower end, a contactor secured to said