The field of the invention relates generally to overcurrent protection fuses, and more specifically, to modular fuse holders for overcurrent circuit protection.
Fuses are widely used as overcurrent protection devices to prevent costly damage to electrical circuits. Fuse terminals typically form an electrical connection between an electrical power source and an electrical component or a combination of components arranged in an electrical circuit. One or more fusible links or elements, or a fuse element assembly, is connected between the fuse terminals, so that when electrical current through the fuse exceeds a predetermined limit, the fusible elements melt and open one or more circuits through the fuse to prevent electrical component damage.
A variety of different types of fuse holders are known providing electrical interfaces for overcurrent protection fuses. Such fuse holders are typically wired into circuitry with line and load side terminals, and the fuses complete an electrical connection within the fuse holder between the line and load side terminals. Existing fuse holders, however, have not completely met the needs of those in the art, and improvements are desired.
Non-limiting and non-exhaustive embodiments are described with reference to the following Figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
For power distribution purposes, fuses are sometimes arranged in and enclosed by a panelboard, sometimes referred to as a control panel. Other circuit protection components such as circuit breakers are also commonly used in combination with fuses in panelboards. A main service device connects a power supply to and from the panelboard, and the circuit breakers and fuses typically provide circuit protection to branch circuits being fed from the panel through the main disconnect. When the main service device is a disconnect switch it can be used to de-energize all the branch circuits, or the individual branch circuits can be de-energized using the circuit breakers while the main disconnect remains connected and the other branch circuits are still supplied with electrical power. Additionally, when electrical fault conditions occur, the circuit protectors (e.g., the breakers and the fuses) may be selectively coordinated so that only the affected branch circuit or feeder circuit may be interrupted while the other branch circuits and feeder circuits continue normal, full power operation.
Recently, panelboards have been developed use with compact fusible switching disconnect devices that provide both fuse capabilities and switching capabilities in a single housing. The compact package size of such devices eliminates a need for separately provided and separately wired circuit breakers common to conventional panelboard designs. This allows in a reduction in size of the panelboard, and a considerable increase in the interrupting rating per volume of the panelboard over conventional panelboards. An exemplary compact panelboard of this type, as well as the compact switching disconnect devices for the panelboard, are described in U.S. patent application Ser. No. 11/941,212 filed Nov. 16, 2007 and Ser. No. 12/691,344 filed Jan. 21, 2010, the disclosures of which are hereby incorporated by reference in their entirety. Further adaptations are desirable to configure the panelboards for particular uses, while still achieving further benefits of compact, space saving design with enhanced performance capabilities.
The panelboard 100 is shown for illustrative purposes only, and the fuse holder assembly 102 accordingly may be utilized with other panelboards while achieving at least some of the benefits described below. The panelboard 100 is therefore provided in the present discussion for purposes of illustration rather than limitation.
The fuse holder assembly 102 includes a nonconductive fuse holder body 104 including a top surface 106 and a bottom surface 108 opposing the top surface 106, left and right side surfaces 108 and 100 opposing one another and interconnecting the top and bottom surface 106 and 108, and lateral side surfaces 114 and 116 extending between and interconnecting the top, bottom, left and right surface 106, 108, 110 and 112.
The body 104, including the surfaces 106, 108, 110, 112, 114 and 116 collectively define an enclosure or receptacle 116 (best shown in
In an exemplary embodiment, the body 104 and the lever arm 118 is configured to accommodate and accept a cylindrical fuse described further below. The body 104 may be formed from a nonconductive material such as plastic or another suitable material according to known techniques such as molding processes or others known in the art. In the exemplary embodiment shown, the body 104 is formed with a compact size and profile, and has an exemplary height H (
In the embodiment shown, the lateral surface 112 includes an aperture 124 therein, and an actuator slot 126 is exposed through the surface 112 so that the lever arm 118 can be remotely actuated with a mating actuator 128 (
The bottom surface 108 of the body 104 in the illustrated example is formed with a DIN rail slot 130 to facilitate mounting of the fuseholder assembly 102 for use.
First and second fuse clips 132 and 134 (
A line side connection terminal 140 is mechanically and electrically connected to the fuse clip 132, and a load side connection terminal 142 is mechanically and electrically connected to the second fuse clip 134. In the example shown, the line side connection terminal 140 is a panelboard clip and the load side terminal 142 is a wire lug terminal. It is appreciated, however, that a variety of alternative terminal structure is known in the art and could likewise be utilized in other embodiments. Also in the exemplary embodiment shown, the line and load side connection terminals 140, 142 each respectively define a non-switchable current path to one of the first and second fuse clips 132, 134. In other embodiments, one or more switching contacts could be associated with one of the line or load side connection terminals 140, 142 to provide a switchable current path through the fuse 120. Exemplary switching elements and arrangements are described in the applications referenced above and may be utilized in such an embodiment. Alternatively, other switching arrangements could be likewise be utilized.
The panelboard clip 140 extends from the bottom surface 108 (
As shown in
The line and load side terminals 140, 142 and the fuse clips 132, 134 may be configured such that the assembly 102 may conform to accepted standards in the industry concerning their electrical ratings and other factors. Such standards include, but are not necessarily limited to UL and IEC standards familiar to those in the industry.
One or more fusible links or elements (not shown), or a fuse element assembly, is contained within the body 150 and connected between the fuse terminal elements 136, 138 so that when electrical current through the fuse 120 exceeds a predetermined limit, the fusible elements melt and open the circuit path through the fuse 120.
As such, when the fuse 120 is installed in the fuseholder assembly 102, the fusible element or elements that extend between the fuse terminals 136, 138 define a conductive current path for current to flow between the fuse clips 132, 134, and in turn completes a circuit path between the line and load side terminals 140, 142 of the assembly 102. When the fusible element or elements operate in response to specified current conditions, however, no current is conducted between the fuse terminal elements 136, 138 and the line side terminal 146 becomes electrically isolated from the load side terminal 142. The fuse 120 must then be replaced to restore operation of the circuitry.
The fuse 120 may be a photovoltaic fuse attachable to the panelboard 100 as part of a power distribution system in a solar powered electrical network. In different embodiments, the fuse 120 may more specifically be a UL248-xx or IEC 60269-2-1 photovoltaic fuse having an operating voltage of about 1000 Vdc, an amperage rating of about 1 A to about 32 A, and an interrupting rating of about 33 kA. In the example shown in
Because of operating differences in solar powered systems versus other power distribution networks, it is important the photovoltaic fuse 120 not be replaced with another and generally incompatible type of fuse. Because different types of fuses, however, can be relatively easily confused this presents practical concern to system administrators. The consequences of having a mismatched fuse installed in the fuse holder assembly 102 can be significant. Accordingly, the assembly 102 includes features to prevent this from happening.
Turning now to
When the fuse 120 is inserted into the sleeve 155, the stub 158 may be received in the depression 152 in the fuse terminal element 136 and the end face 154 (
The lever arm 118 in the illustrated embodiment is an integrally formed or single piece element including the sleeve 155, the actuator slot 126, and other features described herein. The lever arm 118 may be fabricated from plastic according to known techniques.
The lever arm 118 includes generally opposed first and second ends 160 and 162. The end 160 defines the finger grip 122 and the open face of the sleeve 155. The end 162 is rotatably mounted to the fuse holder body 104 proximate the top surface 106 (
As still another enhancement, the lever arm 118 may be configured with an audible click feature so that a user can know if the arm 118 is completely closed. Such an audible click feature can be implemented in a variety of ways and is believed to be within the purview of those in the art.
It may also be shown in
The sensors in the housing, via the wires 224, are connected in parallel with the fuse 120 in the assembly 102 and may monitor voltage conditions, for example, across the fuse. When the fusible element operates and the fuse opens, the voltage drop is detected and a signal may be sent from the accessory 220 to a remote location to indicate the open fuse.
In the embodiment shown in
Particulars of the monitoring assembly 220 are described in detail in U.S. Pat. No. 7,576,630, the disclosure of which is hereby incorporated by reference in its entirety.
The actuator 128 (also shown in
The benefits of the invention are now believed to have been amply illustrated in connection with the exemplary embodiments disclosed.
An embodiment of a fuse holder assembly has been disclosed including: a nonconductive fuse holder body defining a fuse receptacle, the fuse holder body including a top surface and a side surface including an aperture; a lever arm adapted to receive and retain a cylindrical fuse having first and second conductive terminal elements, the lever arm including opposing first and second ends, the first end being rotatably mounted to the fuse holder body proximate the top surface and a portion of the first end being exposed and accessible through the aperture in the side surface, the lever arm being pivotal about the first end such that the second end is selectively positionable between an open position and a closed position relative to the fuse holder body, the open position providing access to insert or remove the cylindrical fuse from the lever arm and the closed position preventing access to the cylindrical fuse; first and second fuse clips mounted to said body, wherein the respective first and second fuse clips engage the first and second conductive terminal elements when the cylindrical fuse is received therein and the lever arm is in the closed position, and wherein the first and second fuse clips are disengaged from the first and second conductive terminal elements when the cylindrical fuse is received in the lever arm and the lever arm is in the open position; and line and load side connection terminals each associated with one of the first and second fuse clips, the line and load side connection terminals each respectively defining a non-switchable current path to one of the first and second fuse clips.
Optionally, one of the line and load side connection terminals may be a panelboard clip extending from the fuse holder body. The fuse holder body may include a bottom surface opposite the top surface, and the panelboard clip may include a first portion extending substantially perpendicularly to the bottom surface and a second portion extending substantially parallel to the bottom surface. The first portion of the fuse clip may extend through and project from the bottom surface, thereby spacing the second portion from the bottom surface. The panelboard clip may be integrally formed with one of the first and second fuse clips. The fuse holder assembly may further include a panelboard, with the panelboard clip attachable to the panelboard.
The lever arm may be configured to reject an incompatible fuse, including a UL Supplemental fuse, a class CC fuse, and an IEC 10x38 fuse. The lever arm may define an axial sleeve configured to receive the fuse, with the sleeve including an abutment surface for the cylindrical fuse and a fuse rejection stub projecting therefrom. The stub may be substantially aligned with a longitudinal axis of the cylindrical fuse when the fuse is received in the sleeve. One of the first and second conductive terminal elements of the cylindrical fuse may include an indentation, with the stub being received in the indentation. The fuse may be a photovoltaic fuse.
A portion of the first end of the lever arm may define an actuator slot, with the actuator slot being exposed and accessible through the aperture in the side surface. The lever arm may optionally define a shank lock opening at the second end.
A status module may optionally be separately provided from the nonconductive body and configured to transmit a signal to a remote device when the cylindrical fuse operates to open a current path between the first and second fuse clips. The status module may be configured to simultaneously monitor multiple cylindrical fuses. The status module may include an actuator coupled to an actuator slot of the fuse holder assembly, whereby when the actuator slot is rotated as the lever arm is opened, the actuator is also rotated and causes the status module to be reset.
At least one of the line and load side connection terminals may optionally include a dual wire box lug terminal. An audible tactile click may be associated with one of the opened and closed positions of the lever arm. A height of the fuse holder may be less than about 72 mm. A width of the fuse holder may be about 17.5 mm or less.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.