This invention relates generally to fuses, and, more particularly, to fused disconnect switches.
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 opens one or more circuits through the fuse to prevent electrical component damage.
In some applications, fuses are employed not only to provide fused electrical connections but also for connection and disconnection, or switching, purposes to complete or break an electrical connection or connections. As such, an electrical circuit is completed or broken through conductive portions of the fuse, thereby energizing or de-energizing the associated circuitry. Typically, the fuse is housed in a fuse holder having terminals that are electrically coupled to desired circuitry. When conductive portions of the fuse, such as fuse blades, terminals, or ferrules, are engaged to the fuse holder terminals, an electrical circuit is completed through the fuse, and when conductive portions of the fuse are disengaged from the fuse holder terminals, the electrical circuit through the fuse is broken. Therefore, by inserting and removing the fuse to and from the fuse holder terminals, a fused disconnect switch is realized.
Known fused disconnects are subject to a number of problems in use. For example, any attempt to remove the fuse while the fuses are energized and under load may result in hazardous conditions because dangerous arcing may occur between the fuses and the fuse holder terminals. Some fuseholders designed to accommodate, for example, UL (Underwriters Laboratories) Class CC fuses and IEC (International Electrotechnical Commission) 10X38 fuses that are commonly used in industrial control devices include permanently mounted auxiliary contacts and associated rotary cams and switches to provide early-break and late-make voltage and current connections through the fuses when the fuses are pulled from fuse clips in a protective housing. One or more fuses may be pulled from the fuse clips, for example, by removing a drawer from the protective housing. Early-break and late-make connections are commonly employed, for example, in motor control applications. While early-break and late-make connections may increase the safety of such devices to users when installing and removing fuses, such features increase costs, complicate assembly of the fuseholder, and are undesirable for switching purposes.
Structurally, the early-break and late-make connections can be intricate and may not withstand repeated use for switching purposes. In addition, when opening and closing the drawer to disconnect or reconnect circuitry, the drawer may be inadvertently left in a partly opened or partly closed position. In either case, the fuses in the drawer may not be completely engaged to the fuse terminals, thereby compromising the electrical connection and rendering the fuseholder susceptible to unintended opening and closing of the circuit. Especially in environments subject to vibration, the fuses may be jarred loose from the clips. Still further, a partially opened drawer protruding from the fuseholder may interfere with workspace around the fuseholder. Workers may unintentionally bump into the opened drawers, and perhaps unintentionally close the drawer and re-energize the circuit.
Additionally, in certain systems, such as industrial control devices, electrical equipment has become standardized in size and shape, and because known fused disconnect switches tend to vary in size and shape from the standard norms, they are not necessarily compatible with power distribution panels utilized with such equipment. For at least the above reasons, use of fused disconnect switches have not completely met the needs of certain end applications.
In the illustrative embodiment of
The housing 104 may be fabricated from an insulative or nonconductive material, such as plastic, according to known methods and techniques, including but not limited to injection molding techniques. In an exemplary embodiment, the housing 104 is formed into a generally rectangular size and shape which is complementary to and compatible with DIN and IEC standards applicable to standardized electrical equipment. In particular, for example, each housing 104 has lower edge 112, opposite side edges 114, side panels 116 extending between the side edges 114, and an upper surface 118 extending between the side edges 114 and the side panels 116. The lower edge 112 has a length L and the side edges 114 have a thickness T, such as 17.5 mm in one embodiment, and the length L and thickness T define an area or footprint on the lower edge 112 of the housing 104. The footprint allows the lower edge 112 to be inserted into a standardized opening having a complementary shape and dimension. Additionally, the side edges 114 of the housing 104 have a height H in accordance with known standards, and the side edges 114 include slots 120 extending therethrough for ventilating the housing 104. The upper surface 118 of the housing 104 may be contoured to include a raised central portion 122 and recessed end portions 124 extending to the side edges 114 of the housing 104.
The fuse 106 of each module 102 may be loaded vertically in the housing 104 through an opening in the upper surface 118 of the housing 104, and the fuse 106 may extend partly through the raised central portion 122 of the upper surface 118. The fuse cover 108 extends over the exposed portion of the fuse 106 extending from the housing 104, and the cover 108 secures the fuse 106 to the housing 104 in each module 102. In an exemplary embodiment, the cover 108 may be fabricated from a non-conductive material, such as plastic, and may be formed with a generally flat or planar end section 126 and elongated fingers 128 extending between the upper surface 118 of the raised central portion 122 of the housing 104 and the end of the fuse 106. Openings are provided in between adjacent fingers 128 to ventilate the end of the fuse 106.
In an exemplary embodiment, the cover 108 further includes rim sections 130 joining the fingers 128 opposite the end section 126 of the cover 108, and the rim sections 130 secure the cover 108 to the housing 104. In an exemplary embodiment, the rim sections 130 cooperate with grooves in the housing 104 such that the cover 108 may rotate a predetermined amount, such as 25 degrees, between a locked position and a release position. That is, once the fuse 106 is inserted into the housing 104, the fuse cover 108 may be installed over the end of the fuse 106 into the groove of the housing 104, and the cover 108 may be rotated 25 degrees to the locked position wherein the cover 108 will frustrate removal of the fuse 106 from the housing 104. The groove may also be ramped or inclined such that the cover 108 applies a slight downward force on the fuse 106 as the cover 108 is installed. To remove the fuse 106, the cover 108 may be rotated from the locked position to the open position wherein both the cover 108 and the fuse 106 may be removed from the housing 104.
The switch actuator 110 may be located in an aperture 132 of the raised upper surface 122 of the housing 104, and the switch actuator 110 may partly extend through the raised upper surface 122 of the housing 104. The switch actuator 100 may be rotatably mounted to the housing 104 on a shaft or axle 134 within the housing 104, and the switch actuator 110 may include a lever, handle or bar 136 extending radially from the actuator 110. By moving the lever 136 from a first edge 138 to a second edge 140 of the aperture 132, the shaft 134 rotates to an open or switch position and electrically disconnects the fuse 106 in each module 102 as explained below. When the lever 136 is moved from the second edge 140 to the first edge 138, the shaft 134 rotates back to the closed position illustrated in
A line side terminal element may 142 extend from the lower edge 112 of the housing 104 in each module 102 for establishing line and load connections to circuitry. As shown in
A lower conductive fuse terminal 156 may be located in a bottom portion of the fuse compartment 150 and may be U-shaped in one embodiment. One of the end caps 154 of the fuse 106 rests upon an upper leg 158 of the lower terminal 156, and the other end cap 154 of the fuse 106 is coupled to an upper terminal 160 located in the housing 104 adjacent the fuse compartment 150. The upper terminal 160 is, in turn, connected to a load side terminal 162 to accept a load side connection to the disconnect module 102 in a known manner. The load side terminal 162 in one embodiment is a known saddle screw terminal, although it is appreciated that other types of terminals could be employed for load side connections to the module 102. Additionally, the lower fuse terminal 156 may include fuse rejection features in a further embodiment which prevent installation of incorrect fuse types into the module 102.
The switch actuator 110 may be located in an actuator compartment 164 within the housing 104 and may include the shaft 134, a rounded body 166 extending generally radially from the shaft 134, the lever 136 extending from the body 166, and an actuator link 168 coupled to the actuator body 166. The actuator link 168 may be connected to a spring loaded contact assembly 170 including first and second movable or switchable contacts 172 and 174 coupled to a sliding bar 176. In the closed position illustrated in
While in an exemplary embodiment the stationary contact 178 is mounted to a terminal 142 having a bus bar clip, another terminal element, such as a known box lug or clamp terminal could be provided in a compartment 182 in the housing 104 in lieu of the bus bar clip. Thus, the module 102 may be used with a hard-wired connection to line-side circuitry instead of a line input bus. Thus, the module 102 is readily convertible to different mounting options in the field.
When the switch actuator 110 is rotated about the shaft 134 in the direction of arrow A, the siding bar 176 may be moved linearly upward in the direction of arrow B to disengage the switchable contacts 172 and 174 from the stationary contacts 178 and 180. The lower fuse terminal 156 is then disconnected from the line-side terminal element while the fuse 106 remains electrically connected to the lower fuse terminal 156 and to the load side terminal 162. An arc chute compartment 184 may be formed in the housing 104 beneath the switchable contacts 172 and 174, and the arc chute may provide a space to contain and dissipate arcing energy as the switchable contacts 172 and 174 are disconnected. Arcing is broken at two locations at each of the contacts 172 and 174, thus reducing arc intensity, and arcing is contained within the lower portions of the housing 104 and away from the upper surface 118 and the hands of a user when manipulating the switch actuator 110 to disconnect the fuse 106 from the line side terminal 142.
The housing 104 additionally may include a locking ring 186 which may be used cooperatively with a retention aperture 188 in the switch actuator body 166 to secure the switch actuator 110 in one of the closed position shown in
A bias element 200 may be provided beneath the sliding bar 176 and may force the sliding bar 176 upward in the direction of arrow B to a fully opened position separating the contacts 172, 174 and 178, 180 from one another. Thus, as the actuator body 166 is rotated in the direction of arrow A, the link 168 is moved past a point of equilibrium and the bias element 200 assists in opening of the contacts 172, 174 and 178, 180. The bias element 200 therefore prevents partial opening of the contacts 172, 174 and 178, 180 and ensures a full separation of the contacts to securely break the circuit through the module 102.
Additionally, when the actuator lever 136 is pulled back in the direction of arrow C to the closed position shown in
In one exemplary embodiment, and as illustrated in
The lever 136, when moved between the opened and closed positions of the switch actuator, does not interfere with workspace around the disconnect module 102, and the lever 136 is unlikely to be inadvertently returned to the closed position from the open position. In the closed position shown in
When the modules 102 are ganged together to form a multi-pole device, such as the device 100, one lever 136 may be extended through and connect to multiple switch actuators 110 for different modules. Thus, all the connected modules 102 may be disconnected and reconnected by manipulating a single lever 136. That is, multiple poles in the device 100 may be switched simultaneously. Alternatively, the switch actuators 110 of each module 102 in the device 100 may be actuated independently with separate levers 136 for each module.
Like the module 102, the module 220 may include the fuse 106, the fuse cover 108 and the switch actuator 110. Switching of the module is accomplished with switchable contacts as described above in relation to the module 102.
Unlike the modules 102 and 220, the module 250 may include a housing 252 configured or adapted to receive a rectangular fuse module 254 instead of a cartridge fuse 106. The fuse module 254 is a known assembly including a rectangular housing 256, and terminal blades 258 extending from the housing 256. A fuse element or fuse assembly may be located within the housing 256 and is electrically connected between the terminal blades 258. Such fuse modules 254 are known and in one embodiment are CubeFuse modules commercially available from Cooper/Bussmann of St. Louis, Mo.
A line side fuse clip 260 may be situated within the housing 252 and may receive one of the terminal blades 258 of the fuse module 254. A load side fuse clip 262 may also be situated within the housing 252 and may receive the other of the fuse terminal blades 258. The line side fuse clip 260 may be electrically connected to the stationary contact 180. The load side fuse clip 262 may be electrically connected to the load side terminal 162. The line side terminal 142 may include the stationary contact 178, and switching may be accomplished by rotating the switch actuator 110 to engage and disengage the switchable contacts 172 and 174 with the respective stationary contacts 178 and 180 as described above. While the line terminal 142 is illustrated as a bus bar clip, it is recognized that other line terminals may be utilized in other embodiments, and the load side terminal 162 may likewise be another type of terminal in lieu of the illustrated saddle screw terminal in another embodiment.
The fuse module 254 may be plugged into the fuse clips 260, 262 or extracted therefrom to install or remove the fuse module 254 from the housing 252. For switching purposes, however, the circuit is connected and disconnected at the contacts 172, 174 and 178 and 180 rather than at the fuse clips 260 and 262. Arcing between the disconnected contacts may therefore contained in an arc chute or compartment 270 at the lower portion of the compartment and away from the fuse clips 260 and 262. By opening the disconnect module 250 with the switch actuator 110 before installing or removing the fuse module 254, any risk posed by electrical arcing or energized metal at the fuse and housing interface is eliminated. The disconnect module 250 is therefore believed to be safer to use than many known fused disconnect switches.
A plurality of modules 250 may be ganged or otherwise connected together to form a multi-pole device. The poles of the device could be actuated with a single lever 136 or independently operable with different levers.
The housing may also include connection openings 306 and access openings 308 in each side edge 310 which may receive a wire connection and a tool, respectively, to establish line and load connections to the fuses 106. A single switch actuator 110 may be rotated to connect and disconnect the circuit through the fuses between line and load terminals of the disconnect device 300.
Retention bars 328 may also be provided on the shaft 134 which extend to the fuses 106 and engage the fuses in an interlocking manner to prevent the fuses 106 from being removed from the device 300 except when the switch actuator 110 is in the open position. In the open position, the retention bars 328 may be angled away from the fuses 106 and the fuses may be freely removed. In the closed position, as shown in
Embodiments of fusible disconnect devices are therefore described herein that may be conveniently switched on and off in a convenient and safe manner without interfering with workspace around the device. The disconnect devices may reliably switch a circuit on and off in a cost effective manner and may be used with standardized equipment in, for example, industrial control applications. Further, the disconnect device may be provided with various mounting and connection options for versatility in the field.
One embodiment of a fusible switch disconnect module is disclosed herein. The module includes a disconnect housing adapted to receive at least one fuse therein; line side and load side terminals communicating with the at least one fuse when the fuse is inserted into the housing; and switchable contacts provided between one of the line side terminal and load side terminal of the disconnect housing and the fuse. The fuse is removably insertable in the housing; and the switchable contacts include at least one stationary contact and at least one movable contact being selectively positionable along a linear axis with respect to the stationary contact between an open position and a closed position to connect or disconnect an electrical connection through the fuse.
Optionally, the stationary contact includes a pair of stationary contacts, and one of the stationary contacts provided on the line side terminal. At least one fuse terminal may be provided and adapted to engage a conductive element of the fuse, wherein the at least one stationary contact includes a pair of stationary contacts, one of the stationary contacts provided on the fuse terminal. A movable bar may be provided with at least one movable contact, and a rotatably mounted switch actuator may be provided to position the movable contact between the open and closed positions, and a bias element may assist moving movable contact to the opened or closed position. At least two movable contacts may be provided and spaced from one another, thereby breaking electrical arcing in two locations spaced from one another when the switchable contacts are opened. An arc chute compartment may be provided in the disconnect housing to contain and dissipate arc energy at a location in the disconnect housing remote from a user. The switchable contacts may be lockable in one of the opened or closed positions, and the switch actuator may include a retention bar to prevent removal of the fuse from the disconnect housing unless the switchable contacts are in the open position. The disconnect housing may be adapted to receive a cartridge fuse or a rectangular fuse module, and modular housings may be provided and ganged to one another, each of the modular housings including switchable contacts to connect or disconnect a respective fuse. The switch actuator may simultaneously connect or disconnect multiple fuses. A fuse cover may extend over the exposed portion of the fuse, the fuse cover being lockable to prevent removal of the fuse from the disconnect housing. An electromagnetic coil may be provided and may be adapted to open the switchable contacts in one of an undervoltage or an overvoltage condition.
An embodiment of a single pole fusible switch disconnect device is also described herein. The device includes a disconnect housing adapted to receive a fuse therein, the fuse being separately provided from the housing and being removably insertable in the housing; line side and load side terminals connecting to the fuse when the fuse is inserted into the housing, at least one of the line and load-side terminals including a first stationary switch contact provided between the respective line side terminal and load side terminal and the fuse; a terminal adapted to engage a conductive element of the fuse when inserted into the disconnect housing, the fuse terminal including a second stationary switch contact provided on the at least one fuse terminal; a sliding bar within the disconnect housing, the sliding bar provided with first and second movable contacts corresponding to the first and second stationary switch contacts; and a rotatably mounted switch actuator to position the sliding bar and first and second movable contacts between an open position and a closed position relative to the first and second stationary switch contacts to connect or disconnect an electrical connection through the fuse.
An embodiment of a multiple pole fusible switch disconnect device is also described herein. The device includes a disconnect housing adapted to receive a plurality of fuses therein, the fuses being separately provided from the housing and being removably insertable in the housing; line side and load side terminals connecting to the respective fuses when the fuses are inserted into the disconnect housing, and stationary switch contacts provided between one of the respective line side terminal and load side terminal for each of the fuses; fuse terminals adapted to receive and engage a conductive element of each respective fuse when inserted into the disconnect housing, each fuse terminal including a second stationary switch contact; sliding actuator bars corresponding to each respective fuse, the sliding bars provided with first and second movable contacts completing electrical connections through each of the fuses when moved to a closed position; and a rotatably mounted switch actuator to position the sliding bars to connect or disconnect an electrical connection through the fuses, the switch actuator simultaneously connecting or disconnecting the fuses. Optionally, the disconnect housing may be adapted to be ganged together with a second disconnect housing.
Still another embodiment of a fusible switch disconnect device is described herein. The device includes means for housing at least one fuse, the fuse being removably insertable into the housing; means for connecting the fuse to a circuit; means for switching the means for connecting to connect or disconnect an electrical connection through the fuse, the means for switching located within the means for housing; and means for actuating the means for switching and selectively positioning the means for switching in opened and closed positions without removing fuse from the means for housing. Optionally, the device may further include means for opening the means for switching to one of a connected or disconnected position in response to one of an overvoltage event and an undervoltage event.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/609,431 filed Sep. 13, 2004 and entitled Fusible Switching Disconnect Modules and Devices, the disclosure of which is hereby incorporated by reference in its entirety.
Number | Date | Country | |
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60609431 | Sep 2004 | US |