The present invention relates generally to electrical switches, and more particularly to blade- or knife-type electrical safety switches.
In electronics, a switch is an electrical component that can break an electrical circuit, for example, to interrupt the current flow or divert the current from one electrical path to another. In blade- or knife-type electrical safety switches, the circuit for each phase is completed through a pivotable, electrically conductive knife or blade, which engages a corresponding contact to electrically connect the line current to the load. In some applications, the blade-type switches are mounted in an enclosure and incorporate an insulating base to carry an incoming line terminal for each phase. One such blade-type electrical switch is disclosed, for example, in U.S. Pat. No. 6,331,684, to Hamid S. Abroy et al., which is incorporated herein by reference in its entirety.
Switches can be of the fusible type or the non-fusible type. In non-fusible switches, the blade engages a contact which is directly electrically connected to the load. In fusible switches, in contrast, the blade engages a contact which is electrically connected to a fuse clip having a fuse seated thereon. The fuse is then electrically connected to the load. U.S. Pat. No. 4,302,643, to Russell Cox et al., and U.S. Pat. No. 5,777,283, to David E. Greer, both of which are incorporated herein by reference in their respective entireties, disclose fusible switch assemblies utilizing the abovementioned construction. Fusible switches are often used in switchboards to distribute power for industrial, commercial, and manufacturing applications.
In some currently designed safety switches, the voltage breaking point of the blades from the jaws takes place at one location, and the generated arc is guided through the arc housing, safely managed, and disposed. In many applications, more power must be distributed through enclosures which are the same size or smaller. For instance, as solar energy becomes more desirable, a higher voltage per pole on the safety switch will be required. This requires increasing the electrical rating of the switch to carry a higher voltage and current density while decreasing the size of the enclosure housing the electrical parts.
When the wattage across a switch is sufficiently large (e.g., 600 Vac per pole and 600 Vdc through two pole (300 Vdc/Pole)), the electron flow across switch contacts can be sufficient to ionize the air molecules between the contacts as the switch is opened or closed, forming an electric arc. The electric arc is very hot, so much so that it can erode the metal surfaces of the switch contacts. Accordingly, there is a need for a switch assembly and switching mechanism that can effectively and efficiently quench arcs generated in high voltage applications, while maintaining a sufficiently small overall footprint. The switch assembly should be economical to manufacture, and be capable of being assembled easier and faster to reduce costs. In addition, field assembly and retrofit should be simplified, and the switch should have widespread application. Another need would be to bring multiple voltage outputs into a multi-pole safety switch and be able to disconnect the power sources with a minimum number of safety switches.
According to some aspects of the present disclosure, the voltage across the safety switch is broken down in two different places and each arc is managed separately, therefore allowing the switch to have a higher voltage per pole. By dividing the arc voltage in half, it can be managed more efficiently and each pole of the switch can be used separately as opposed to using two poles in series. In some embodiments, the foregoing objectives can be achieved while keeping the safety switch in the same approximate dimensions and envelope as existing safety switch assemblies. Moreover, the safety switch assembly of some embodiments meets visible blade requirements and, in some embodiments, can break 600 Vdc or more per pole while meeting the current overload requirements prescribed by standard agencies, such as the Underwriters Laboratory (UL) 98 Standard.
Each safety switch can use two blades in conjunction with an intermediate insulator. The tripartite blade-insulator-blade assembly can be laminated and adapted to pivot about a hinge. A separate jaw can be provided for making contact with each electrically conductive side of the tripartite blade such that the arc voltage is broken at two places and in half.
In accordance with some aspects of the present disclosure, a switch assembly is presented for making and breaking electrical connections in an electrical circuit. The switch assembly includes a platform with first and second electrically conductive jaws operatively attached to the platform. The first jaw is configured to electrically connect to an incoming line of the electrical circuit, whereas the second jaw is configured to electrically connect to an outgoing line of the electrical circuit. The switch assembly also includes a blade with a first electrically conductive plate attached to and spaced from a second electrically conductive plate via an electrical insulator. The blade is pivotably coupled to the platform to rotate between a disengaged position, whereat the blade is electrically decoupled from the first and second jaws, and an engaged position, whereat the blade delivers an electrical current received from the first jaw through the first and second plates to the second jaw.
In other aspects of the present disclosure, a switch assembly is featured for making and breaking electrical connections in an electrical circuit. The switch assembly includes an electrically insulated platform with first and second electrically conductive jaws mounted thereto. The first jaw is configured to electrically connect to an incoming line of the electrical circuit, whereas the second jaw is configured to electrically connect to the outgoing line. The switch assembly also includes a blade with a first electrically conductive plate attached to and electrically insulated from a second electrically conductive plate via an electrical insulator. The blade is pivotably coupled to the platform to rotate between an engaged position, whereat the blade delivers an electrical current received from the incoming line via the first jaw through the first and second plates to the outgoing line via the second jaw, and a disengaged position, whereat the blade is electrically decoupled from the first and second jaws such that the voltage of the electrical load is broken down separately at the first jaw and at the second jaw.
According to other aspects of the present concepts, an electrical distribution device is presented for connecting to an electrical circuit with incoming and outgoing lines. The electrical distribution device includes an enclosure with an electrically insulated platform disposed within the enclosure. A first electrically conductive jaw is mounted to the platform adjacent a second electrically conductive jaw. The first jaw is configured to electrically connect to an incoming line of the electrical circuit, whereas the second jaw is configured to electrically connect to an outgoing line. The second jaw is distinct and spaced from the first jaw. The electrical distribution device also includes one or more blades, each having a first electrically conductive plate attached to and electrically insulated from a second electrically conductive plate via an electrical insulator. An electrically conductive, single-piece mounting hinge pivotably couples the blade to the platform. A rotor is rotatably mounted within the enclosure. The rotor has at least one blade slot receiving the blade therethrough. The rotor is configured to selectively move the blade between a disengaged position, whereat the blade is electrically decoupled from the first and second jaws, and an engaged position, whereat the blade distributes an electrical current received from the incoming line via the first jaw through the first and second plates to the outgoing line via the second jaw.
The above summary is not intended to represent each embodiment or every aspect of the present disclosure. Rather, the foregoing summary merely provides an exemplification of some of the novel features included herein. The above features and advantages, and other features and advantages of the present disclosure, will be readily apparent from the following detailed description of the embodiments and best modes for carrying out the present invention when taken in connection with the accompanying drawings and appended claims.
While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the disclosure is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Referring now to the drawings, wherein like reference numerals refer to like components throughout the several views,
In the embodiment illustrated in
The electrically insulating base 28 of the switch assembly 20, commonly referred to as a line base or platform, generally operates to provide a module for a single phase of a multi-phase circuit. The insulating base 28 can be integrally formed (e.g., via injection molding) of an electrically insulating material, such as a thermoplastic polymer, an example of which is sold by the General Electric Company under the tradename VALOX®. In a multi-phase application, multiple interlocking insulating bases 28 are mounted adjacent one another inside the electrical distribution device 10, each base 28 being connected to a respective line service for a phase. In the illustrated embodiment, the insulating base 28 has a generally square-polyhedron shape with a bottom surface 25 integral with (i.e., manufactured as a single element) opposing sidewalls 27 and 29, each of which extends generally perpendicularly from a respective lateral edge of the insulating base 28. The opposing sidewalls 27, 29 provide the components in the base 28 separation and arc protection from the other phases in adjacent insulating bases. A U-shaped stand 31 is integral with and extends generally perpendicularly from a forward edge of the insulating base 28. The U-shaped stand 31 is configured to mate with and align the arc suppressing housings 42 with respect to the insulating base 28.
In a multi-phase application with a plurality of interlocking insulating bases 28, at least one of the insulating bases 28 is secured to the enclosure 12. For example, threaded fasteners (e.g., screws) or other mounting hardware can be inserted through apertures in the insulating bases 28 to secure the base 28 to the enclosure 12. Then, after at least one of the bases 28 is secured to the enclosure 12, the remainder of the insulating bases 28 can be secured to and operatively supported by a respective adjacent base 28. In the illustrated embodiment, however, each of the insulating bases 28 is not only connected to another base, but is also secured to the enclosure 12.
With reference to both
The rotor 34 of
Each segment 34A, 34B, 34C of the rotor 34 has an integral sleeve 46A, 46B and 46C, respectively. The integral sleeves 46A, 46B, 46C have respective slots 47A, 47B and 47C that extend therethrough, transverse to the longitudinal axis of the rotor 34. Each slot 47A, 47B, 47C is adapted (i.e., shaped and sized) to receive therethrough and engage a corresponding blade 30, as seen in
In the illustrated embodiments, the switch assembly 20 is mated with the switching mechanism 22, which is operable to effect actuation of the switch assembly 20 upon movement of the handle 16. As shown in
In use, the handle 16 outside the enclosure 12 can be selectively moved between “ON” and “OFF” positions as desired by the user. During movement of the handle from one position to the other, the switching mechanism 22 operates to quickly accumulate kinetic energy from the movement of the handle, store the energy, and rapidly release the energy to rotate the rotor 34. Thus, when the switching mechanism 22 releases the stored kinetic energy, the rotor 34 is quickly rotated, which in turn rotates the blade 30 to rapidly engage and disengage the blade 30 from the jaws 38A and 38B. An exemplary switching mechanism that operates in conjunction with the foregoing description is described in extensive detail in U.S. Pat. No. 5,739,488, to Terry A. Cassity et al., which issued on Apr. 14, 1998 and is entitled “Switch Operating Mechanism Including Handle,” and is incorporated herein by reference in its entirety.
As shown in
The arc suppressing housing 42 has a plurality of shelves, designated generally as 65 in
With reference now to
The blade 30 is pivotably coupled to the platform via an electrically conductive mounting hinge 32. In the illustrated embodiment, the mounting hinge has a single-piece, unitary body comprised of a substantially planar base 70 and laterally opposing, substantially parallel tabs 72 and 74 that extend generally perpendicularly from the base 70. The blade mounting hinge 32 is fabricated from an electrically conductive material. In some embodiments, the hinge 32 is made from a single, integral piece of flat copper sheet metal that is initially formed to the required dimensions and is then bent to the desired shape. The mounting hinge 32 operatively attaches to the insulating base 28. By way of non-limiting example, the base 70 of the blade hinge 32 can be provided with apertures 71 for securing directly to the insulating platform 28 with threaded fasteners. The blade 30 is received between the opposing tabs 72, 74. The blade 30 can be pivotably attached to the hinge 32 via a lateral hinge pin 90 (shown in
In the illustrated embodiment, the blade 30 is a tripartite construction comprised of an electrical insulator 84 and at least two electrical conductors: one electrical conductor is represented herein by a first electrically conductive plate 86, whereas the other electrical conductor is represented herein by a second electrically conductive plate (shown hidden in FIG. 4 at 88). In some embodiments, each electrically conductive plate 86, 88 is fabricated from a generally rectangular metal plate, such as copper or aluminum, that is coated with a corrosion resistant plating. The first electrically conductive plate 86 is attached to and spaced from the second electrically conductive plate 88 via the electrical insulator 84.
As seen in
The blade 30 is pivotably coupled to the platform 28 (e.g., via hinge 32) to rotate between a disengaged position (seen in
Depending on whether a fusible or a non-fusible switching assembly is to be employed, a variety of additional components are added to the above described switch assembly 20. In a non-fusible switching assembly, a load terminal is utilized. The load terminal directly contacts and is secured to the bottom of the blade hinge 32. Otherwise, no additional connecting members are typically required. In a fusible switching assembly, additional electrical contacts, an additional insulating base, a fusible member, and a load terminal are required. A more detailed discussion of how various components work to provide a fusible or a non-fusible switching assembly is provided in U.S. Pat. No. 6,331,684, to Hamid S. Abroy et al., which issued on Dec. 18, 2001 and is entitled “Modular Switch Assembly,” incorporated herein by reference above.
The dual breaking electrical joint 120 also includes a multi-layer blade 130. In the illustrated embodiment, the blade 130 is a tripartite construction, although more than three layers is certainly envisioned. The blade 130 includes an electrical insulator 184 that extends between and spans the entire area of first and second electrically conductive plates 186 and 188, respectively. The first electrically conductive plates 186 is attached to and spaced from the second electrically conductive plate 188 via the electrical insulator 184. In this embodiment, the plates 186, 188 are attached to the electrical insulator 184 via layers of adhesive 190.
The blade 130 is pivotably coupled to the platform 128 via an electrically conductive mounting hinge 132. The mounting hinge 132 of
While particular embodiments and applications of the present invention have been illustrated and described, it is to be understood that the invention is not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the spirit and scope of the invention as defined in the appended claims. To that extent, elements and limitations that are disclosed, for example, in the Abstract, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference or otherwise
Number | Name | Date | Kind |
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2224380 | Crabbs et al. | Dec 1940 | A |
2571864 | Graybill | Oct 1951 | A |
3240888 | Rys et al. | Mar 1966 | A |
3335399 | Rys | Aug 1967 | A |
3339047 | Rys et al. | Aug 1967 | A |
3346711 | Rys et al. | Oct 1967 | A |
4302643 | Cox et al. | Nov 1981 | A |
5057654 | Meyer et al. | Oct 1991 | A |
5322982 | Leger et al. | Jun 1994 | A |
5609245 | Cassity et al. | Mar 1997 | A |
5737195 | Cassity et al. | Apr 1998 | A |
5739488 | Cassity et al. | Apr 1998 | A |
5746306 | Cassity et al. | May 1998 | A |
5777283 | Greer | Jul 1998 | A |
6313416 | Abroy et al. | Nov 2001 | B1 |
6331684 | Abroy et al. | Dec 2001 | B1 |
Number | Date | Country |
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197 34 676 | Feb 1999 | DE |
0 062 369 | Oct 1982 | EP |
Entry |
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Schneider Electric; Solar Disconnect Switches; Heavy Duty Safety Switches (Fusible and Non-Fusible) on direct Current and Photovoltaic Systems; downloaded Sep. 9, 2010; (1 page). |
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Number | Date | Country | |
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20120085736 A1 | Apr 2012 | US |