US3593251A

US3593251A - Fuse device

Info

Publication number: US3593251A
Application number: US752848A
Authority: US
Inventors: James C Wilson
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1968-08-15
Filing date: 1968-08-15
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13

Abstract

An improved fuse device comprises an insulating housing and fuse means supported in the housing with external terminals extending out through openings at opposite ends of the housing for enabling connection of the fuse means in an electric circuit. The fuse device is a multipole fuse device, and terminal connectors, on the external terminals, are housed in cavities at one end of the housing.

Description

United States Patent [72] inventor James C. Wilson Beaver, Pl. [2|] Appl. No. 752.848 [22] Filed Aug. l5, I968 [45] Patented July 13,197! [73] Assignee Westinghouse Electric Corporation Pittsburgh, Pl.

[541 FUSE DEVICE 8 Claims, 5 Drawing Figs.

[52] U.S.Cl 337/186 [51] Int. Cl "."H0lh85/20 [501 Field 0! Search 337/186, 281, 188; 335/7, I97. I61

(56} References Cited UNITED STATES PATENTS 3,281,555 10/!966 Fister 337/188 329L940 12/[966 Kozacka 337/161 3,032,631 5/l962 Edmundsw. 337/186(X) 3,077,525 2/l963 Dyer 337/! 86(X) Primary Examiner Harold Broome Atrorney.r-A. T. Stratlon. C. L. McHale and W. A. Elchik ABSTRACT: An improved fuse device comprises an insulating housing and fuse means supported in the housing with external terminals extending out through openings at opposite ends of the housing for enabling connection of the fuse means in an electric circuit. The fuse device is a multipole fuse device, and terminal connectors, on the external terminals, are housed in cavities at one end of the housing SHEEI 1 OF 4 INVENTOR James C. Wilson av a. 46.144

ATTORNEY l gu l 1 1 f PATENIED JUL 3 3 WI wnNEssEs mew 971 M ifiv PATENTEU JUN 3197:

SHEET 2 DF 4 FUSE DEVICE CROSS-REFERENCE TO RELATED APPLICATION The multipole fuse device of this invention is herein disclosed as being connected to a multipole circuit breaker of the type disclosed in the patent to Nick Yorgin et al. U.S. Pat. No. 3,462,7l6issued Aug. [9, I969.

PRIOR ART AND BACKGROUND OF THE INVENTION In the U.S. Pat. to Swain No. 2,950,370, there is disclosed a circuit interrupter comprising a multipole molded-case-type circuit breaker and a separate fuse unit mounted at each of the two opposite ends of the circuit breaker with the fuse units comprising current-limiting fuses for increasing the interrupting capacity of the circuit interrupter. The fuse device of this invention is an improvement over fuse devices of the type disclosed in the Swain patent in that the fuse device of this invention is relatively simple in construction; relatively easy to manufacture and assemble; and there are fewer terminal connections in the circuit through the fuse device. The boltontype fuse device of this invention is also an improvement over fuse devices of the type disclosed, for example, in the U.S. Pats. to Jacobs Jr. No. 2,734,110, to Fister U.S. Pat. No. 3,281,555 and to Hitchcock U.S. Pat. No. 3,319,027.

SUMMARY OF THE INVENTION An improved circuit interrupter comprises a multipole circuit breaker and a multipole fuse device connected to the breaker by means of bolt-on-type connecting means. The fuse device comprises an insulating fuse housing and fuse means supported within the housing. The fuse housing comprises a front housing part having a plurality of compartments therein and a back pan housing secured to the front housing part. A separate fuse means is mounted in each of the compartments of the front housing part, and each compartment is filled with an arc-quenching filler material such as sand. Each of the separate fuse means comprises a pair of terminals, a pair of insulating spacers supporting the terminals and a plurality of metal fusible elements connected between the terminals. Each of the terminals comprises an internal leg connected to the fusible elements and an external leg that extends generally normal to the internal leg and that is adapted to receive bolton-type connection with a conductor. The external legs of the spaced terminals extend out through slots in the opposite ends of the front housing part, and the back housing part comprises a generally flat front surface that closes off the compartment openings of the front housing part to complete the housing assembly. A resilient gasket is provided between the front and back housing parts. The fuse housing is shaped to provide a plurality of cavities at one end thereof for receiving solderless terminal connectors that are connected to the external terminal legs at one end of the fuse unit to enable connection of the circuit interrupter in an electric circuit. Each of the fuse means is a unitary preassembled device. During the assembly operation each of the fuse means is dropped into the associated compartment of the front housing part. A gasket is then positioned at the opening end of the front housing part. Thereafter, the compartments of the front housing part are filled with an arc-quenching filler material such as sand, and the back housing part is secured into position to complete the assembly. Each of the fuse means comprises indicator means. When any of the fuse means blows the associated indicator means will be released to automatically protrude out through an opening in the front of the fuse housing to provide a visual indication that the fuse means has blown.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view, with parts broken away, of a circuit interrupter constructed in accordance with principles of this invention;

FIG. 2 is a sectional view taken generally along the line Il-Il of FIG. 1;

FIG. 3 is an exploded side view, with parts broken away, of the fuse device seen in FIGS. 1 and 2;

FIG. 4 is an end view of the parts of FIG. 3 looking in the direction of the IV-IV arrows of FIG. 3; and

FIG. 5 is a perspective view of the gasket seen in FIGS. 2

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, there is shown, in FIGS. 1 and 2, a three-pole circuit interrupter 5 comprising a three-pole circuit breaker 7 and a three-pole fuse device 9 connected to the circuit breaker.

The circuit breaker 7 is of the type that is more specifically described in the patent to Nick Yorgin et al., U.S. Pat. No. 3,462,716 issued Aug. 19, I969. Thus, only a brief description of the circuit breaker 7 is given herein.

Referring to FIGS. I and 2, the circuit breaker 7 is a threepole circuit breaker comprising an insulating housing 11 and a circuit breaker mechanism I3 supported in the housing II. The housing 11 comprises a back insulating housing base I5 and a front insulating housing cover 17 cooperating with the base I5 to enclose the circuit breaker mechanism. The housing I'l comprises suitable insulating barrier means separating the housing into three internal compartments for housing the three-pole units of the circuit breaker. The circuit breaker mechanism 13 comprises an operating mechanism 19, a latch mechanism 2! and a thermal-and-magnetic trip device 23.

A stationary contact 25, a movable contact 27 and an arcextinguishing unit 29 are provided for each pole unit of the circuit breaker. The stationary contact 25, for each pole unit, is fixedly mounted on the inner end of a conducting strip 3] that extends outward to an external cavity where a well-known type of solderless terminal connector 33 is secured to the end of the conductor 31. The movable contact 27, for each pole unit, is mounted on a contact arm 35 that is mounted on a switch arm 37 that is fixedly secured to an insulating tie bar 39. The switch arms 37 for the three-pole units are secured to the common tie bar 39, and the tie bar 39 is mounted for pivotal movement between open and closed positions.

The operating mechanism I9 comprises an inverted generally U-shaped operating lever 41, an overcenter spring means 43 and a toggle 45. An insulating handle 47 is connected to the lever 41, with the handle 47 protruding through a suitable opening in the front of the breaker housing. The lever 41 is mounted for pivotal movement about the inner ends of the legs thereof. The toggle 45 is connected to the switch arm 37 of the center pole unit.

The contacts are manually opened by movement of the handle 47 from the "on" position to the "off" position. This movement moves the line of action of the overcenter springs 43 to cause collapse of the toggle 45 to thereby cause opening movement of the switch arm 37 in the center pole unit. Since all three switch arms are connected to the tie bar 39 for simultaneous movement, this movement simultaneously moves the three switch arms 37 to the open position. The contacts are manually closed by reverse movement of the handle 49 from the ofF position to the on" position, which movement moves the line of action of the overcenter springs 43 to erect the toggle 45 to thereby move the centerpole switch arm 37, and therefore all of the switch arms 37, to the closed position seen in FIG. 2.

The operating mechanism I9 comprises a trip member 49 that is latched by means of the latch device 21. In each pole unit, the trip device 23 comprises a bimetal 51, a magnetic yoke 53 and a magnetic armature 55. Upon the occurrence of an overload above a first predetermined value, the bimetal 51 is heated and flexes to the right whereupon an adjusting screw 57 engages a common trip bar 59 to move the trip bar 59 to a releasing position to release a latch 61 which then releases the trip member 49. Upon release of the trip member 49, the springs 43 operate to move the trip member 49 to thereby effect collapse of the toggle 45 and opening movement of the switch arms 37 in a well-known manner. Following a thermal tripping operation, the circuit breaker is reset and relatched by movement of the handle 47 to the full "off" position to thereby move the trip member 49 back to the latched position seen in FIG. 2. Upon the occurrence of an overload above a second predetermined value higher than the first predetermined value, the armature 55 is instantaneously attracted to the yoke 53 to thereby move the trip bar 59 to the tripping position to effect tripping operation in the same manner as was hereinbefore described with regard to the thermal tripping operation.

Referring to FIG. 2, the circuit through each pole unit extends from a generally L-shaped conductor 65, through a flexible conductor 67, the bimetal a flexible conductor 71, the contact arm 35, the movable contact 27, the stationary contact 25, the conductor 3 I, to the solderless tenninal connector 33. As can be seen in FIG. 2 in each pole unit there is a pair of cavities at the opposite ends of the housing. The conductor 33 is supported in the cavity on the right, and the conductor 65 extends into the cavity on the left. In each pole unit the conductor 65 is positioned to receive connection of one of the terminals of the fuse device in a manner to be hereinafter more specifically described.

The fuse device 9 comprises an insulating fuse housing indicated generally at 75. The fuse housing 75 comprises an insulating front housing part 77 (FIGS. 3 and 4) and an insulating back housing part 79. The front housing part 77 is molded with insulating barrier means to form three adjacent compartments 8]. A separate fuse means indicated generally at 83 is supported in each of the compartments 8!.

Each of the fuse means 83 (FIGS. 3 and 4) comprises a pair of

terminals

85 and 87. Each of the

terminals

85, 87 comprises an internal generally planar leg 89 that is bentover at the lower end thereof to provide an external generally planar leg 91 that extends generally normal to the plane of the associated leg 89. Each of the internal legs 89 is provided with a plurality of recesses on the inside flat face thereof, and a plurality of metallic fusible elements 93 are supported on the inside faces of the legs 89. Each of the elements 93 is positioned at the op posite ends thereof in recesses in the legs 89, and the ends are soldered into position to fixedly support each element on the inside faces of the legs 89. As can be understood with reference to FIGS. I and 3, there are two rows of elements 93 between each pair of legs 89 with each row comprising three elements 93 that are slanted to provide elongation of the elements 93 within the space between the faces of the internal legs 89. As can be seen in FIGS. 2 and 3, one row comprises three parallel elements 93 slanted in one direction and the other row comprises three parallel elements slanted in another direction. Each of the fusible elements 93 is provided with a plurality of slots at opposite sides thereof to provide a plurality of portions of reduced cross section that will fuse or blow upon the occurrence of overload current conditions in a wellknown manner. A pair of rigid insulating supporting and spacing members 95 are provided between each pair of terminals 83 to support and space the terminals in the manner disclosed in FIGS. 3 and 4. As can be seen in FIG. I, each of the legs 89 is provided with a slot at the upper end thereof and the upper rigid insulating spacer 95 is provided with a pair of projections that are positioned within the slots to locate the upper spacer 95. As can be understood with reference to FIGS. 3 and 4, each of the legs 89 is provided with a notch at the lower end thereof, and the lower insulating spacer 95 is provided with projections that engage in the notches to position the lower spacer 95. A metallic fusible strain wire 97 extends through an opening in the lower insulating spacer 95 and is soldered over at 99 to secure the strain wire 97 to the lower insulating spacer 95. The strain wire 97 extends through an opening in the upper insulating spacer 95 and is secured to an indicator A compression spring I03 is positioned between the indicator I01 and the front face of the upper insulating spacer 95 to bias the indicator Illl upward (FIG. 3) and to maintain the strain wire 97 under tension. As can be understood with reference to FIG. 3, lateral movement of the insulating spacers 95 is prevented by the positioning of the spacers in the slots in the terminals 83, and the compression spring 103 biases the spacers inwardly, which movement is limited by the engagement of the projections of the spacers with parts of the terminals 83, so that the spacers 95 are fixedly mounted and positioned to space and support the terminals 83. The external leg 9| (on the left as seen in FIG. 3) is provided with an opening therein, and a solderless terminal connector I05 is connected to the leg 9] by means of a screw I07 that extends through the opening in the leg 9! and is threaded into a portion of the solderless terminal connector I05. The leg 91 seen on the right in FIG. 3 is provided with an opening therein, and a member I09, having a tapped opening therein aligned with the opening in the leg 91, is fixedly secured to the under surface of the leg 9] to receive a screw or bolt in a manner to be hereinafter described.

As will be understood with reference to FIG. 3, there is a slot 111 at one end of each of the compartments 81 of the front housing part 77, and a cavity 1 I3 opposite each slot 1 I I. There is a slot 115 in the front housing part 77 at the opposite end of each of the compartments 8!. When it is desired to assemble the fuse device 9, the front housing part 77 is turned over. A tubular insulating sealing member 117 is placed over the indicator I01 and spring 103 of each of the fuse means 85, and each of the fuse means 85 is then dropped downward into the associated cavity 81 with the member I17 engaging a shoulder portion 119 at the front of the associated compartment and with the indicator 10! being positioned in an opening [21 at the front of the compartment 83. As was Previously set forth, each of the fuse means 83 is a unitary structure, as shown in FIG. 3, with the parts being retained in position by means of the spacers 95. Inward movement of each of the fuse means 83 is limited when the front portions of the external legs 91 engage the insulating surfaces at the front of the slots III, I15. During the movement of each fuse means 83 into position, the associated solderless terminal connector I05 moves into the associated cavity 113. After the three fuse means 83 are properly positioned in the associated cavities of the front housing part 77, a resilient gasket 127 is placed on the housing part 77 and an arc-quenching filler material, such as sand, is poured into the compartments 81, with the filling material flowing in the compartments to fill the voids in the compartments. As can be seen in FIG. 5, the gasket 127 is provided with openings 129 that align with the compartments 8] and openings 13] that align with the cavities 113. With the fuse means 83, filler material 128 and gasket I27 in position, the lower housing part 79 is placed into position against the gasket I27, and the

housing parts

77, 79 are then secured together. There are four pockets I35 (FIG. 3) in the lower part of the housing part 79, which pockets are shaped to key with four nuts 137. The nuts 137 are positioned in the ockets I35, and four elongated bolts 139 are placed through suitable openings in the front housing part 77 and back housing part 79. The bolts 139 are threaded into the nuts 137 to draw the

housing parts

77, 79 together sandwiching the gasket 127 therebetween to fixedly secure the

housing parts

77, 79 together. The gasket I27 serves to prevent the escape of filler material from the housing. As can be understood with reference to FIGS. 3 and 4, the front surface 141 of the lower housing part 79 is a flat planar surface. When the

housing part

77, 79 are secured together, the fuse device is turned over to the upright position seen in FIG. 2. In the upright position, the lower surfaces of the legs 91 of each of the three fuse means 83 rest on the gasket 127, that is positioned on the flat front surface 141 of the lower housing part 79, to thereby support the three fuse means 83 on the front of the housing part 79. Thereafter, the small space between the front portions and sides of the legs 91 and the peripheries of the openings of the slots III, 115 is filled by means of an insulating cement 143 that is painted into these openings. The cement 143 is a type of cement that may be painted into position to take a firm set without actually getting hard so that if relative movement of the fuse means 83 occurs the cement I43 will not crack. The

cement [43 serves to prevent the escape of the filler material through the openings through which the external legs 91 extend.

As can be understood with reference to FIGS. 1-3, there are three pole-unit compartments in the insulating housing 75 with the back housing part 79 forming the backwalls of the three compartments and with the hood-type front housing part 75 forming the sidewalls, end walls and front walls of the three compartments.

When the fuse device 9 is completely assembled, the fuse device is removably connected to the circuit breaker 7 by means of a plurality of screws When it is desired to connect the fuse device 9, the fuse device is moved adjacent to the one end of the circuit breaker 7 with each of the external legs 91 of the terminals 87 extending into the associated cavity of the housing ll of the circuit breaker below the associated terminal conductor 65. An opening in each leg 91 is aligned with an opening in the associated conductor 65. Thereafter, a screw 15! may be passed through the aligned openings in the

members

65, 91 and threaded into the member 109 that is secured to the associated leg 91. Thus, the screws l5l fixedly connect the terminals 87 to the terminals 65. As can be seen in FIGS. 1 and 4, the insulating housing 75 ofthe fuse device 9 is provided with a pair of slots I53 between adjacent pole units. The insulating housing 11 of the circuit breaker 7 is provided with a pair of slots I55 (FIG. 1) between adjacent pole units. The

slots

153, 155 provide electrical clearance between adjacent terminals 87 of the three adjacent pole units. As can be understood with reference to FIGS. l--3, each of the cavities 113 is separated by suitable insulating barrier means, that form the cavity, to provide adequate insulation between adjacent terminals 85 and adjacent solderless terminal connectors 105.

Referring to FIGS. 1 and 2, the circuit through each pole unit of the multipole fuse device 9 extends from the solderless terminal I05 through the terminal 85, the fusible elements 93, the terminal 87 to the terminal 65 to which the terminal 87 is connected by means of the screw I51. Upon the occurrence of a severe overload above a third predetermined value higher than said second predetermined value, the fusible elements 93, which are in parallel in the circuit of the associated overloaded pole unit, will fuse or blow instantaneously to interrupt the overload with a current-limiting action. The heat that is generated by the circuit interruption in the associated fuse device is conducted through the filler material to the fusible strain member 97. When the fusible strain member 97 fuses, the compression spring l03 biases the indicator 101 frontward which movement is limited by the engagement of a shoulder portion [57 on the indicator 101 with the surface 119 of the front housing part 77. The indicator 101 protrudes through the top opening 1217 in the actuated position thereof, to provide a clear visual indication that the fuse means 83 has blown. When a maintenance man sees that a particular fuse means has blown, he can remove the fuse device 9 and replace the blown fuse means 83 with a similar fuse means 83. Thereafter, the fuse device 9 can be installed and connected to the circuit breaker 7 in the same manner as was hereinbefore described. During the course of replacing the blown fuse means 83, the filler material 127 can be replaced with filler material that his not been subjected to a circuit interruption.

For certain applications, conducting means can be added to connect at least a portion of the length of the fusible strain wire 97 in parallel with the fusible elements 93 between the

terminals

85, 87. in these applications, the flow of current will fuse the strain wire 97 when the elements 93 fuse upon the occurrence of a severe overload above the third predetermined value.

I claim:

I. A fuse device comprising an insulating housing forming a compartment therein and having opening means therein at opposite ends of said compartment, fuse means supported on said insulating housing and comprising a pair of fuse terminals, each of said fuse terminals comprising an internal leg and an external leg extending from the internal leg, fusible-element means connected between said internal legs, said housing comprising a back housing part and a front housing part, said fuse means being supported at the front of said back housing part, said front housing part comprising a hood-type housing part positioned over said internal legs and said fusible-element means to cooperate with said back housing part to enclose said fuse means within said compartment except for said external legs which protrude through said opening means at opposite ends of said compartment, each of said internal legs extending from back-to-front in said compartment with each fuse terminal being shaped at the back thereof such that the associated external leg extends generally normal to the direction of extension of the associated internal leg at the back of the associated internal leg, laid hood-type front housing part forming the front internal wall the internal sidewalls and the internal end walls of said compartment, laid back housing part forming the internal backwall of said compartment, said housing having opening means at the front thereof, said fuse means comprising indicator means positioned in proximity to said opening means and operating automatically to protrude through said opening means when said fuse means has blown to provide an external visual indication of the blown condition of said fuse means, and an arc-quenching filler material filling the space within said compartment.

2. A fuse device according to claim 1, said fusible-element means comprising a plurality of elongated fusible elements supported between said internal legs extending lengthwise between said internal legs, an arc-quenching filler material material substantially filling said compartment, and gasket means between said front housing part and said back housing part.

3. A multipole fuse device comprising an insulating housing, said insulating housing forming a plurality of compartments therein and having opening means therein at opposite ends of each of said compartments, a separate fuse means for each of said compartments, each of said separate fuse means comprising a pair of fuse terminals, each of said fuse terminals comprising a generally planar internal leg and a generally planar external leg extending from the associated internal leg along a plane generally normal to the plane of the associated internal leg, fusible-element means for each of said fuse means, each of said fusible-element means comprising a plurality of elongated fusible elements supported between the associated spaced internal legs, insulating spacing means between the internal legs of each of said fuse means supporting the associated internal legs in a generally parallel relationship and supporting the associated internal legs with the associated fusible-element means therebetween as a unitary assembly, said housing comprising a back housing part and a front housing part, said back housing part comprising a generally planar front surface, resilient gasket means on said generally planar front surface, each of said fuse means being supported on said resilient gasket means at the front of said back housing part, said front housing part comprising a hood-type front housing part forming a compartment for each of the poles of said fuse device with said generally planar front surface on said back housing part serving as a backwall of each of said compartments, said front housing part being positioned over said plurality of fuse means with each of said compartments enclosing a separate one of said fuse means except for the external legs of the fuse means and with the opposite external legs of each of said fuse means extending out through the associated opening means at the opposite ends of the associated compartment, and securing means drawing said front housing part and back housing part together compressing said resilient gasket means therebetween to support and house said plurality of fuse means.

4. A multipole fuse device accordin to claim 3, said front housing part forming a separate cavity opposite each of said the associated one external leg, and the other external leg of each of said fuse means having opening means therein for receiving bolt-on-type connection with a terminal conductor.

5. A multipole fuse device having a front a back a pair of opposite sides and a pair of opposite ends, said fuse device comprising a two-part insulating fuse housing comprising an insulating front housing part and an insulating back housing part, means securing said insulating front housing part and said insulating back housing part together to form said two-part insulating fuse housing, said two-part insulating fuse housing forming a plurality of adjacent side-by-side pole-unit compartments therein. said two-part insulating housing forming a plurality of adjacent side-by-side pole-unit cavities therein at a first end of said insulating fuse housing with each of said poleunit cavities being opposite a different one of said pole-unit compartments, said insulating fuse housing having opening means therein at each of the opposite ends of each of said compartments,

a separate fuse means for each of said compartments, each of said fuse means comprising a first terminal and a second terminal spaced end wise in the associated compartment from the associated first terminal, each of said first terminals comprising an internal part in the associated compartment and an external part extending through said opening means at the first end of the associated compartment into the associated cavity, a terminal connector on the external part of each of said first terminals in the associated cavity, each of said second terminals comprising an internal part in the associated compartment and an external part extending through the associated opening means at the second end of the associated compartment, each of said fuse means comprising fusible-element means, each of said fusible-element means comprising a plurality of elongated fusible elements supported between the internal parts of the first and second terminals extending lengthwise between the internal parts of the first and second terminals, each of said fuse means comprising insulating spacing means between the internal parts of the associated first and second terminals supporting the associated first and second terminals in a spaced relationship whereby each of said fuse means is mounted in the associated compartment as a unitary assembly,

and an arc-quenching filler material substantially filling each of said compartments.

6. A multipole fuse device according to claim 5, each of said first terminals comprising an elongated first leg which is the internal part thereof and which extends from back-to-front in the associated compartment with a bend at the back thereof to provide a second leg which is the external part thereof and which extends out through the associated opening means at the first end of the associated compartment, and each of said second legs extending generally normal to the associated first leg.

7. A multipole fuse device according to claim 6, and gasket means between said insulating front housing part and said insulating back housing part.

8. A multipole fuse device according to claim 7, said front housing part being a hood-type housing part forming the inter nal front walls of said compartments and forming the internal and walls of said compartments and forming the internal sidewalls of said compartments, and said back housing part forming the internal backwalls of said compartments.

Claims

1. A fuse device comprising an insulating housing forming a compartment therein and having opening means therein at opposite ends of said compartment, fuse means supported on said insulating housing and comprising a pair of fuse terminals, each of said fuse terminals comprising an internal leg and an external leg extending from the internal leg, fusible-element means connected between said internal legs, said housing comprising a back housing part and a front housing part, said fuse means being supported at the front of said back housing part, said front housing part comprising a hood-type housing part positioned over said internal legs and said fusible-element means to cooperate with said back housing part to enclose said fuse means within said compartment except for said external legs which protrude through said opening means at opposite ends of said compartment, each of said internal legs extending from back-to-front in said compartment with each fuse terminal being shaped at the back thereof such that the associated external leg extends generally normal to the direction of extension of the associated internal leg at the back of the associated internal leg, said hood-type front housing part forming the front internal wall the internal sidewalls and the internal end walls of said compartment, said back housing part forming the internal backwall of said compartment, said housing having opening means at the front thereof, said fuse means comprising indicator means positioned in proximity to said opening means and operating automatically to protrude through said opening means when said fuse means has blown to provide an external visual indication of the blown condition of said fuse means, and an arc-quenching filler material filling the space within said compartment.

4. A multipole fuse device according to claim 3, said front housing part forming a separate cavity opposite each of said compartments, one of the external legs of each of said fuse means projecting into the associated cavity, a separate solderless terminal connector in each of said cavities connected to the associated one external leg, and the other external leg of each of said fuse means having opening means therein for receiving bolt-on-type connection with a terminal conductor.

5. A multipole fuse device having a front a back a pair of opposite sides and a pair of opposite ends, said fuse device comprising a two-part insulating fuse housing comprising an insulating front housing part and an insulating back housing part, means securing said insulating front housing part and said insulating back housing part together to form said two-part insulating fuse housing, said two-part insulating fuse housing forming a plurality of adjacent side-by-side pole-unit compartments therein, said two-part insulating housing forming a plurality of adjacent side-by-side pole-unit cavities therein at a first end of said insulating fuse housing with each of said pole-unit cavities being opposite a different one of said pole-unit compartments, said insulating fuse housing having opening means therein at each of the opposite ends of each of said compartments, a separate fuse means for each of said compartments, each of said fuse means comprising a first terminal and a second terminal spaced end wise in the associated compartment from the associated first terminal, each of said first terminals comprising an internal part in the associated compartment and an external part extending through said opening means at the first end of the associated compartment into the associated cavity, a terminal connector on the external part of each of said first terminals in the associated cavity, each of said second terminals comprising an internal part in thE associated compartment and an external part extending through the associated opening means at the second end of the associated compartment, each of said fuse means comprising fusible-element means, each of said fusible-element means comprising a plurality of elongated fusible elements supported between the internal parts of the first and second terminals extending lengthwise between the internal parts of the first and second terminals, each of said fuse means comprising insulating spacing means between the internal parts of the associated first and second terminals supporting the associated first and second terminals in a spaced relationship whereby each of said fuse means is mounted in the associated compartment as a unitary assembly, and an arc-quenching filler material substantially filling each of said compartments.

8. A multipole fuse device according to claim 7, said front housing part being a hood-type housing part forming the internal front walls of said compartments and forming the internal end walls of said compartments and forming the internal sidewalls of said compartments, and said back housing part forming the internal backwalls of said compartments.