Fuse to circuit breaker adapter

STATEMENT OF GOVERNMENT INTEREST

The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefore.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to protective electrical circuit devices and more particularly to a circuit breaker adapter that enables a circuit breaker to be utilized in a fuse holder.

2. Background

The United States Navy and Coast Guard have a number of combat ships fitted with highly automated guns that utilize an electrically powered gun mount to control the gun. The Mark gun (MK-75) is a three-inch gun with a range of ten 10 nautical miles and can fire up to eighty rounds per minute. The high level performance guns are lightweight and have low manning requirements. The Mk-75 is well suited for installation on smaller combat vessels, frigates and cutters.

The first United States produced gun mount for the MK-75 was delivered in August 1978. Currently, MK-75 guns are on some guided missile frigates and some Navy hydrofoils. The Coast Guard's cutters are equipped with automated guns MK-75 guns, where the gun mount is remotely controlled. The gun mounts control the train and elevation of the gun, and the protective electrical devices that are a part of the electrically powered gun mount systems are starting to exhibit signs of aging, as evidenced by a higher incidence of blown fuses. This spike in demand has depleted the entire government stock of these legacy parts, which are SCR fuses. Furthermore, the cost and the time to replace are unacceptably too long and high in cost. The United States Navy and Coast Guard need a timely and cost effective solution to keep the electrically powered gun mounts operational.

SUMMARY OF THE INVENTION

The disclosed invention is an adapter that enables a circuit breaker to be installed in place of a fuse in a fuse holder on a vessel and in any other suitable application. Installation of a new fuse is commonly referred to “plug and play”, where a blown fuse is pulled-out of a pair of electrically conductive gripping clips in a fuse holder and the new fuse is pushed-in the pair of clips, therein reestablishing a closed, working, protected electrical circuit. One advantage of a circuit breaker is that with an overage current, the circuit breaker trips protecting the circuit but unlike a blown fuse, which must be replaced, the tripped circuit breaker only needs to be reset. Some circuit breakers are self-resetting.

Another advantage of the invented adapter is that the existing fuse panels may be used, obviating the cost and time needed to install a circuit breaker panel. The option to rewire gun control panels to accommodate circuit breakers is obviated. Installing a circuit breaker panel requires a lot of time, effort, and money.

An aspect of the invention is that the adapter is suitable for a single fuse holders and fuse holders that may hold a plurality of fuses. The adapter permits the simultaneous use of both circuit breakers and fuses. A fuse holder has an electrically insulating plate with one or more insular elongate bays, wherein each bay has a pair of clamping fuse clips. A common variation of a fuse clip has a pair of opposing electrically conductive contacts for clamping a knife-blade-end of a fuse. A fuse with a blade element, for example, an SCR fuse, includes a center section that is an elongate cylindrical element and a pair of outboard elongate sections that are similar in shape to a blade. The blade element has an overall length that extends lengthwise through the cylindrical element. The blade element has a center fusible portion that is enclosed within the cylindrical element. The elongate sections have a blade thickness, and the elongate sections project from opposing ends of the center elongate cylindrical element.

The fuse is positioned in the fuse holder by forcing the blade element into the clips, causing each clip to springedly widen as it receives the elongate section of the blade element. A gripping force is generated by the clips on the blade element, securing the fuse in the bay of the fuse holder.

The invented adapter enables the use of a minimally modified circuit breaker in a legacy fuse holder. The circuit breaker has a first pronged terminal and a second pronged terminal spaced by a separation length. A first arcuate conductive articulable extension is pivotally attached to the first pronged terminal. A second arcuate conductive articulable extension is pivotally attached to the second pronged terminal. The articulable extensions may be pivoted outwardly from an assembly position where they are closely aligned with the pronged terminals to a use position. The articulable extensions are nearly orthogonal to the pronged terminals, and aligned to be nearly longitudinal. The arcuate conductive articulable extensions have an individual thickness that is comparable to the thickness of the elongate sections of the blade element and an individual length that cumulatively spans a distance comparable to the overall length of the fuse minus the separation length of the pronged terminals. Depending on the selection of the circuit breaker, the individual length of the articulable extensions is usually about the length of the elongate sections of the blade element. The articulable extensions are arcuate to permit pivoting from the assembly position to the use position.

The adaptor further includes an electrical insulating chute shaped housing, where the housing is a contiguous block of material that receives the modified circuit breaker with the articulable extensions and the gripping clips. The housing has a first accessible open cavity and a second accessible open cavity, where each accessible open cavity is open on a bottom side (the bottom side of the housing covers the clips mounted on the fuse holder's electrically insulating plate). Each accessible open cavity is sufficiently large to accommodate a clip gripping an articulable extension. The top side of the housing is chute shaped, and it has two slotted sockets, where their center points are spaced by the separation length. Each socket extends to one of the accessible open cavities. The sockets provide passages large enough to accommodate the articulable extensions and terminals in the assembly position.

The circuit breaker adapter is assembled by plugging the articulable extensions into sockets in the chute shaped portion of the housing. The modified circuit breaker is seated in the chute section of the housing and the articulable extensions are protruding from the bottom side of the housing. Assembly is completed by pivoting the articulable extensions outboard to the use position, into the accessible open cavities of the housing. The chute shaped housing is locked onto the circuit breaker, and the extensions are positioned to engage the clips on a fuse holder. The housing has an overall length that may span the entire length of the bay of the fuse holder, but this extra length is generally not required.

Another advantage of the invented circuit breaker adapter is that a tripped reset button may be reset without removing the circuit breaker adapter or cutting off the power.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing invention will become readily apparent by referring to the following detailed description and the appended drawings in which:

FIG. 1 is an elevated plan view of a conventional legacy fuse holder that can hold up to three fuses, where currently there are two fuses, each fuse in a bay having a pair of clamping fuse clips, where each clip grips an end of a blade section therein securing the fuse;

FIG. 2 is an elevated view of a conventional n SCR fuse with a conductive blade that functions in part as a structural element for the SCR fuse;

FIG. 3 is an elevated perspective view of a circuit breaker fitted with a circuit breaker adapter that enables a modified circuit breaker to be utilized in a fuse holder;

FIG. 4 is an elevated plan view of a three bay fuse holder, as shown in FIG. 1, that is currently holding two circuit breakers, each of which are fitted with a circuit breaker adapter enabling the circuit breakers to be utilized instead of or in combination with fuses having a blade;

FIG. 5 is a frontal view of a circuit breaker adapter;

FIG. 6a is a frontal view of a modified circuit breaker having extensions that are shown in the assembly position (A), where the extensions are closely aligned with the pronged terminals, where a first arcuate conductive articulable extension is pivotally attached to the first pronged terminal, and a second arcuate conductive articulable extension is pivotally attached to the second pronged terminal;

FIG. 6b is a frontal view of the modified circuit breaker shown in the use position (U), wherein the arcuate conductive articulable extensions are pivotally rotated out board to a use position where the articulable extensions are nearly orthogonal to the pronged terminals, and closely aligned as to be nearly longitudinal;

FIG. 6c is an exploded view of an articulable extension, a pronged terminal, and a rivet;

FIG. 7a is a plan view of a front side of the adapter's electrical insulating chute shaped housing, that insulates and supports the modified circuit breaker and the housing has accessible open cavities that are sufficiently large to accommodate springedly widened clips gripping articulable extensions in the use position;

FIG. 7b is an overhead view of a top side of the adapter's housing illustrating the approximate size and position of the sockets that receive the pronged terminals fitted with articulatable extensions;

FIG. 7c is a plan view of a bottom side of the adaptor's electrical insulating chute shaped housing illustrating the accessible open cavities; and

FIG. 7d is a cross-sectional view of the chute shaped housing, taken along sectional line 7d-7d of FIG. 7a, illustrating how the pivoting action transitions (T) from an assembly position (A) to a use position (U) places positions articulatable extensions in the accessible open cavity and the action effectively locks the modified circuit breaker on the housing.

DETAILED DESCRIPTION OF THE INVENTION

The invented adapter enables a circuit breaker to be installed in place of a conventional fuse in a conventional fuse holder. In an exemplary embodiment, the circuit breaker has planar pronged terminals that protrude from a side of the circuit breaker. The circuit breaker has a thickness that is narrow enough to fit in a bay of a fuse holder. The prior art, as shown in FIG. 1, illustrates a conventional fuse holder 100 that may hold up to three fuses 120 (see FIG. 2), and in the instant case the holder has two fuses. In the illustrated fuse holder, there are only two fuses 120a,120b in the holder 100 so that the reader can better understand the art. The fuse holder 100 has three bays 110a,110b,110c. The outside bays 110a, 110c are nearly mirror images, differing only in the location of the fuse holder fastening hole 102 in the base plate 104. Outside bay 110a has an upper left insulator 115a1 and a lower left insulator 116al. Outside bay 110c has an upper right insulator 115cr and a lower right insulator 116al. Bays 110b and 110c share an upper left insulator 115c1 and a lower left insulator 116c1. Bays 110a and 110c share an upper right insulator 115cr and a lower right insulator 116cr. Each bay has a width that is about 110w. In the applicant's illustrated invention there is additional insulation for each bay, and the additional insulation is not shared, irrespective of the number of fuse bays.

In the illustrated fuse holder 100 bay 110c has two clamping clips 111c, 112c that are ready to receive the fuse 120 with knife-blade-ends 121,122 (FIG. 2). Both of the clamping clips 111c,112c are springedly closed. In the other two bays 110a,110b the clips 112a, 111a and 112b, 111b are gripping and securing fuses 120a,120b. The clips 112a, 111a and 112b, 111b are springedly widened. In the case of clips 112a, 111a and 112b, 111b the fuses' blade sections 121a,122a,121b,122b have a thickness that determines how far the clips 112a, 111a and 112b, 111b are widened. Widening causes the clips to tighten their grip on the blade elements.

The fuse 120 shown in FIG. 2 and FIG. 1 has a blade element 124 with sections 121,122. The illustrated fuse may be an SCR fuse. It includes a center section 123 which is substantially an elongate cylindrical element. The outboard elongate sections 121,122 are similar in shape to a blade. The blade element has an overall length 1201 that extends lengthwise through the cylindrical element. The blade element 124 has a center fusible portion that is enclosed within the cylindrical element 123, which may be made of glass.

The fuse may be replaced by an inventive circuit breaker adapter shown in FIG. 3, where the circuit breaker adapter may be utilized in a fuse holder. In an exemplary embodiment, the circuit breaker adapter 10 includes a modified circuit breaker and a housing 20 with a bottom that may receive the fuse holder clips. The modified circuit breaker 51 is seated in a chute section of the housing 20. The chute portion of the housing 20 has a right wall 25′, a left wall 25, a right ledge 22s′, a left ledge 22s, a lower second right wall 25s′, a lower second left wall 25s, and a floor 22f. A bottom side 58 of the modified circuit breaker 50 is supported by the chute's right ledge 22s′ and the chute's left ledge 22s, spanning a lower channel 22c having a floor 22f (see FIG. 7a). A portion of the circuit breaker's left wall 56 is lodged against the chute's left wall 25, and a portion of the circuit breaker's right wall 56′ is lodged against the chute's right wall 25′. The circuit breaker has a reset button 52.

As shown in FIG. 6b, the illustrated circuit breaker is held together with rivets 53, 53′ and 53″. As shown in FIG. 3, rivet assembly 53″ extends below the front plate 55 from the bottom side 58 into the lower channel 22c. The rivet assembly 53″ extends between the lower second right wall 25s′ and the lower second left wall 25s toward the floor 22f of the chute.

FIG. 4 illustrates the fuse holder shown in FIG. 1, which in one exemplary variation is a Bussmann™ sfb1060-03 buss fuse block. The width of a bay 110w, as shown in FIG. 1, and the thickness of the circuit breaker 50t are approximately the same. The circuit breaker may be slightly thicker as it is elevated above the fuse holders' insulation walls 115al-cr, 116al-cr. Note, that in FIG. 4, in bays 110a and 110b, the circuit breaker adapters 10a,10b cover the clips. Only clips 111c, 112c are visible, and ready to receive the circuit breaker adapter 10c (not specifically shown).

A frontal view of the circuit breaker adapter having a modified circuit breaker is shown in FIG. 5.

As illustrated in FIG. 6a, a circuit breaker is modified to have extensions 70,70′. Brass is known to be suitable material. After modification the circuit breaker is renumbered to 51 reflecting the modifications. The modifications result in a pivotally attached first arcuate conductive articulable extension 70 to the first pronged terminal 60, and a pivotally attached second arcuate conductive articulable extension 70′ to the second pronged terminal 60′. An exploded view is shown in FIG. 6c of second arcuate conductive articulable extension 70′. The articulable extension 70′ is broadly similar to the fuse blade sections 121,122a shown in FIG. 2, however there are major departures. In FIG. 6c, the articulable extension 70′ has a length 70l′, a thickness 70t′, an inboard hole 77′ near an inboard end 76′ adjacent to an acruate edge 74′, a beveled corner 75′, and a tapered edge 72 that extends from the inboard end 76′ to an outboard end 71′. The inboard hole 77′ is axial to a terminal hole 62′ in the pronged terminal 60′. A fastening element 80′ axially connects the extension 70′ and the terminal 60′, permitting friction rotation.

Returning to FIG. 6a, extension 70 is similarly attached to terminal 60. The length between the points of attachment is 80 to 80′ is indicated by 601. This length is a separation length, which is about the distance between the center points 27c, 27c′ of sockets 27, 27′ as illustrated in FIG. 7b. As shown in FIG. 6b, the arcuate corners 74,74′ permit rotation of the extensions 70,70′ without impinging either the bottom side 58 or the rivet assembly 53″ of the circuit breaker. As shown in FIG. 6a, the extensions 70,70′ are in the assembly position (A).

In FIG. 6b, the articulable extensions 70,70′ are in the use position (U). When an extension is rotated in the socket 27,27′ during the transition (T) the corner 75,75′ of the extension 70,70′ could impact the wall 25s,25s′(see FIG. 7a) or a wall 29,29′ in the accessible open cavity as shown in FIG. 7d. To prevent impact, the corners 75,75′ may be beveled to a point where they are rounded.

FIG. 6b illustrates the modified circuit breaker 51 with the extensions in the use position. The housing 20 would normally prevent this view.

The adaptor's electrical insulating chute shaped housing 20 is illustrated in FIG. 7a. The housing 20 insulates and supports the modified circuit breaker 51 (not shown-see FIG. 6b). The housing has a left top side 22, a right top side 22′, a left end side 23, a right end side 23′, a bottom side 26, a center chute shaped section that includes a chute section's right side 25′, a chute section's left side 25, a right ledge 22s′, a left ledge 22s, a channel section having a lower second right side 25s′, a lower second left side 25s, and a floor 22f. As shown in FIGS. 7c and 7d, the housing has accessible open cavities (left cavity 28 and a right cavity 28′), where the right cavity 28′ is shown in FIG. 7d.

The modified circuit breaker 51 is attached by simply plugging the pronged terminals fitted with extensions (see FIG. 6a) into sockets. The sockets 27,27′ are shown in FIG. 7b. The center points of the sockets 27c,27c′ are labeled. The sockets are located in the ledges 22s,22s′, and the sockets are sufficiently large to accommodate the terminals with fastened extensions.

The sockets extend to the accessible open cavities 28,28′, as shown in the plan view of the bottom 26 side of the housing 20. The cavities 28,28′ are sufficiently large to accommodate the springedly widened clips 111c, 112c gripping the articulable extensions 70,70′ in the use position.

Rotation of the extensions 70,70′ and one of the cavities 28′ is shown in FIG. 7d, which is a cross-sectional view of the housing, taken along sectional line 7d-7d of FIG. 7a. The FIG. 7d illustrates how the pivoting action from the assembly position (A) through transitions (T) to the use position (U). The action effectively locks the modified circuit breaker 51 on the housing 20. As may be easily seen, once in the use position the tapered edge 72 is ready to engage a clip. The extension cannot rotate any further as the end of the extension 76 limits movement as does the ceiling 29c,29c′ of the cavities. Once engaged with the clips 111c, 112c, the springedly tensioned clips restrain any further movement. The adapter 10 is secured in a fused holder and the modified circuit breaker 51 is in electrical contact through the extensions 70, 70′, which are secured in the clips 111c, 112c. The clips 111c, 112c are individually and completely surrounded by an insulating housing. The housing may be made of Nylon® or other suitable material.

Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.