Patent Description:
Circuit breakers are used to interrupt current flow in the event of abnormal operating conditions, such as a short circuit or current overload. To interrupt current flow, electrical contacts are separated. Electrical arcing may occur between the contacts as they are separated, resulting in potential damage to the contacts as well as other components in the circuit breaker from electrical and heat energy generated from arcs or arcing. The quick extinction of this arc is desired not only to minimize damage to the circuit breaker but to interrupt the current as quickly as possible to protect the wires and load. AC circuits are generally used in many of today's power systems however, DC circuits are becoming more popular due to the use of batteries, DC converters, LED lighting, DC motors, and photovoltaic arrays all of which are inherently DC powered. And since a DC circuit is more difficult to interrupt current flow as compared to an AC circuit due to the natural current zero crossing inherent in an AC circuit, the traditional circuit breakers designed for use in an AC circuit have a difficult time interrupting a DC circuit. So, there is a need for a circuit protective device which can efficiently interrupt DC and protect a DC circuit. <CIT> discloses an apparatus for extinguishing an arc, comprising an arc chute including: a pair of opposing side walls, arc plates arranged between the side walls, the body having an open area and a plurality of slots through which to facilitate gas flow. A back wall is arranged on a backside of the body, the backwall including at least one magnet that generates a magnetic field to redirect an arc in the open area toward one of the side walls. <CIT> discloses an apparatus for extinguishing an arc according to the preamble of claim <NUM>.

In accordance with an embodiment, an apparatus according to claim <NUM> is provided for extinguishing an arc. The apparatus includes an arc chute that includes a pair of opposing side walls, a non-magnetic body arranged between the side walls, and a back wall arranged on a back side of the non-magnetic body. The side walls are formed of an electrically insulating material. The non-magnetic body has an open area and a plurality of slots through which to facilitate gas flow. The back wall includes at least one first insulator and at least one magnet. The at least one first insulator is arranged between the at least one magnet and the open area and configured to electrically isolate the magnet from the non-magnetic body. The magnet can generate a magnetic field to redirect an arc in the open area toward one of the side walls, depending on current direction.

The side-walls can be formed by inserting the arc chute inside of the arc chamber or there may be side walls created from an insulating material which can also be used to support the metal arc plate stack.

In various embodiments, the non-magnetic body can be a non-ferromagnetic body, which comprises a plurality of stacked metal plates that are spaced-apart to form the plurality of slots therebetween. Each plate of the plurality of stacked metal plates can have a pair of arms extending from a base which is connected therebetween. The open area is formed between the pair of arms of the stacked metal plates. Each plate of the plurality of stacked metal plates can have a U-shaped profile or a π-shaped profile.

The at least one first insulator can include a plurality of spaced apart grooves or recesses configured to engage and support an outer surface of the base of corresponding plates from the plurality of stacked metal plates, and is configured to support the at least one magnet. The at least one first insulator can also include one or more vent openings through which to facilitate gas flow out from the open area. The at least one magnet can have a first end and an opposite second end. The first and second ends can each have an opposite magnetic polarity with one of the first or second end facing toward the open area across the at least one first insulator.

The at least one first insulator can also include at least one pocket for supporting the at least one magnet. The at least one first insulator can further include one or more vent openings through which to facilitate gas flow out from the open area, the at least one magnet comprises a plurality of magnets, and the at least one first insulator includes a plurality of pockets for supporting the plurality of magnets at different locations. The plurality of pockets can be separated by the one or more vent openings.

The apparatus can further include a pair of second insulators each including a plurality of spaced apart grooves or recesses configured to engage and support corresponding plates from the plurality of stacked metal plates. Each second insulator can be engaged to the plurality of plates of a respective one of the pair the side walls. Furthermore, each of the pair of second insulators can be configured to engage an open end of a corresponding arm of the pair of arms. The arc chute can also include at least one side gas channel. The first and/or second insulators can comprise of nylon.

In another embodiment, a circuit protective device is provided, which includes a first electrical contact, and a movable second electrical contact, which when engaged with the first electrical contact, is configured to enable current flow thereacross to a circuit. The circuit protective device can further include the apparatus for extinguishing an arc or an arc chute, such as described herein. The circuit protective device can include a case for housing the first and second electrical contacts and the arc chute. The side walls of the arc chute of the apparatus can be formed as part of the case or side walls of an arc chamber in the case. The circuit protective device can be a bi-directional DC circuit breaker or still function as an AC circuit breaker.

The present disclosure relates to an arc chute for a circuit protective device, such as a circuit breaker. The arc chute includes a pair of opposing side walls, a back wall and a non-magnetic body for extinguishing an arc. The non-magnetic body is arranged between the side walls and back wall, and includes an open area (or space), also referred to as an arc quenching chamber. The back wall (e.g., toward a vent side) can include a back insulator to support and electrically isolate one or more magnets from the pair of side walls. The one or more magnets on the back wall can generate a magnet field to redirect arcing in or around the open area toward one of the side walls of the arc chute, such as for example due to disengagement of electrical contacts of the circuit protective device,. The non-magnetic body can include a stack of non-magnetic metal plates (e.g., non-ferromagnetic plates, etc.), which are spaced-apart to provide a plurality of slots through which to facilitate the flow of gas (or gas flow), such as produced as a result of arcing, out from the open area of the non-magnetic body between the opposing side walls. The arc chute can also be designed with gas channels on an outer side surface and/or outer back surface of the non-magnetic body to control or facilitate movement of gas flow to one or more vents or venting components of the circuit protective device.

Such an arc chute configuration with the magnet(s) arranged at a back (or vent-side) of the arc chute can break-up arcs quickly and effectively through the use of magnetic fields to redirect an arc(s) to one of the side walls, where the slotted design can also help to extinguish arcs. Furthermore, such an arc chute configuration is more versatile than an arc chute that employs magnets on the sides of the chute to redirect arcing towards a back of the chute. An arc chute with magnets on the sides can be used primarily with unidirectional circuit breakers, e.g., where current flow is in one direction (or polarity) through a circuit protective device. In contrast, the arc chute configuration of the present disclosure can be used with bi-directional circuit breakers in which the terminals are interchangeable, e.g., first and second terminals are connectable to the load and line wiring respectively, or vice-a-versa. By positioning the magnet(s) at the back of the arc chute, arcs in a bi-directional circuit breaker can be redirected to one or the other of the side walls of the arc chute according to the direction (or polarity) of current flow through the circuit breaker. The arc chute configuration of the present disclosure can also incorporate gas channels to direct or facilitate movement of gases to the vent(s) of the circuit breaker or arc chamber which includes the arc chute, the vent and electrical contact assembly. The arc chute configuration can also incorporate one or more insulators to support the non-magnetic body or portions thereof (e.g., a stack of non-magnetic or deionizing plates), and insulator materials such as nylon or other materials which can produce gases as a result of arcing to further help extinguish an arc(s) and to cool down the arc chute. The magnetic field created by the permanent magnet also serves to cool the arc by increasing convective losses due to the increased turbulence produced by the magnetic field produced by the permanent magnet. The faster the arc can be cooled, the quicker and more efficient the arc extinction process becomes. Various arc chute designs or configurations will be described in greater detail below with reference to the figures.

<FIG> show front and back perspective views of an arc chute <NUM> in accordance with a first embodiment. The arc chute <NUM> can be employed in a circuit protective device to extinguish an electric arc which may result from operation of the circuit protective device, such as the engagement or disengagement of electrical contacts therein. The circuit protective device can be a circuit breaker, such as an AC or DC circuit breaker, a contactor, or other circuit protective device. The arc chute <NUM> includes a non-magnetic body <NUM> for extinguishing an arc, a pair of opposing side walls <NUM>, and a back wall <NUM>. The non-magnetic body <NUM> includes a plurality of slots <NUM> for facilitating gas flow, and an open area (or space) <NUM>. The non-magnetic body <NUM> is arranged between the side walls <NUM>. The side walls <NUM> can be formed of an electrically insulating material, such as a non-magnetic or other insulating material (e.g., fiberboard or glass polyester). The back wall (or vent end) <NUM> includes a back insulator <NUM> to support at least one magnet <NUM> (e.g., a permanent magnet), and to electrically isolate the magnet <NUM> from the non-magnetic body <NUM>. The magnet <NUM> can be retained in a pocket <NUM> (e.g., pocket, recess or recessed area, etc.) of the back insulator <NUM>. As will be described further below, the magnet <NUM>, which is arranged at the back of the arc chute <NUM>, is configured to generate a magnet field(s) to redirect arcs generated in or around the open area <NUM> toward one of the side walls <NUM> (or one of the sides of the non-magnetic body <NUM>).

In this example, the non-magnetic body <NUM> can be formed of a plurality of stacked plates <NUM> (e.g., deionizing plates) which are spaced-apart from each other to form the plurality of slots <NUM> (e.g., slots, openings, through-holes, etc.). For example, each of the plates <NUM> of the body <NUM> can include a base <NUM> and a pair of opposing arms <NUM> which extend from the base <NUM>. The open area <NUM> is formed or provided between the pair of opposing arms <NUM> of the stacked plates <NUM>. The non-magnetic body <NUM> and its plates <NUM> can have a U-shape profile. The plates <NUM> can be made of a non-magnetic material such as non-ferromagnetic material, non-magnetic steel (e.g., <NUM> or <NUM> stainless steel) or other non-magnetic metals (e.g., copper, brass, etc.), and can be formed by stamping, molding or other manufacturing techniques to obtain a desired shape.

As further shown, the arc chute <NUM> can utilize the back insulator <NUM> and front (or side) insulators <NUM> to support the plates <NUM> of the body <NUM>. For example, the back insulator <NUM> and front insulators <NUM> can include a plurality of spaced-apart grooves or recesses (e.g., blind slots, etc.) <NUM> and <NUM> respectively, which are configured with a size and shape to engage and support corresponding plates from the plurality of stacked plates <NUM>. Each front insulator <NUM> can be positioned (or arranged) on an outer side surface or portion at or around an open end of each of the pair of side walls <NUM>. The insulators <NUM> and <NUM> can be formed of an electrically insulating material to electrically isolate the magnet <NUM> from the non-magnetic body <NUM> and its component(s). The insulators <NUM> and <NUM> can also be formed of a suitable material (e.g., nylon, nylon composite, etc.) which can produce gases as a result of arcing to help extinguish an arc and to cool down the arc chute. Furthermore, as shown in <FIG>, the back insulator <NUM> can include at least one pocket <NUM> for supporting and retaining the magnet <NUM>. Although not shown in this example, the insulators <NUM>, <NUM> can include vent openings to facilitate the flow of gases out from the open area <NUM>. The back insulator <NUM> can partially surround the magnet <NUM> as shown, or alternatively fully surround the magnet <NUM>.

As generally shown by the bi-directional arrows in <FIG>, the side walls <NUM> can be arranged relative to a respective outer side of the non-magnetic body <NUM>. The proximity of each side wall <NUM> to a respective side of the body <NUM> as well as its dimension, shape or size can be configured according to the arc chute design, such as whether a front/side insulator <NUM> is to be utilized, whether side gas channels are incorporated, the size and shape of the plates of the body <NUM>, the configuration of an arc chamber including its housing, and so forth. In various example embodiments, the side walls <NUM> can be formed by inserting the arc chute inside of the arc chamber (e.g., side-walls of the arc chamber become the side-walls of the arc chute) or side walls can be created from an insulating material which can also be used to support the stack of plates.

As shown in <FIG>, the magnet <NUM> can generate a magnet field(s), as generally indicated by the example field lines, around the arc chute <NUM> and across the open area <NUM>. In this example, one magnetic pole (e.g., North (N) or South (S)) of the magnet at one end/side is configured to face the direction of the open space <NUM> and the opposite magnetic pole at an opposing end/side faces away from the open space <NUM>. A moving arm <NUM> of a contact assembly of a circuit protective device can include or carry a moving electrical contact <NUM> (on an underside generally identified by broken lines). The moving arm <NUM> can pass through the open area <NUM> to engage or disengage from another electrical contact <NUM> (e.g., a stationary contact) of a contact assembly of the circuit protective device to enable or interrupt current flow, respectively. The electrical contact <NUM> can be arranged below (e.g., immediately below) the arc chute <NUM>. When arcing is produced in the open area <NUM> between the electrical contacts <NUM> and <NUM> (e.g., as the moving electrical contact <NUM> disengages from the contact <NUM> and moves through the open area <NUM>), the resulting arc is redirected by the magnetic field generated by the magnet <NUM> toward one of the pair of side walls <NUM> to extinguish the arc.

<FIG> is a top-sectional view of a portion of an arc chute <NUM> in accordance with a second embodiment. The arc chute <NUM> can include the same or similar components as the arc chute <NUM> of <FIG>, except that a back insulator 150A can include at least one vertical vent opening <NUM> (e.g., opening, slot, through-hole, etc.) and can support a plurality of vertical magnets 170A in respective pockets 154A as shown in <FIG>. The vertical vent opening(s) <NUM> can facilitate the flow of gases out from the open area <NUM>. The arc chute <NUM> can also include additional front/side insulators (e.g., <NUM> in <FIG> or others described herein) arranged on an outer surface of the side walls <NUM>.

As shown in <FIG>, the magnets 170A can generate magnet fields, as shown by the example field lines, around the arc chute <NUM> and across the open area <NUM>. In this example, a moving arm <NUM> of a circuit protective device can include or carry a moving electrical contact <NUM> (on an underside generally identified by broken lines). The moving arm <NUM> can pass through the open area <NUM> to engage or disengage the moving electrical contact <NUM> to or from another electrical contact <NUM> (e.g., a stationary contact), respectively, of the circuit protective device to enable or interrupt current flow, respectively. When arcing is produced in the open area <NUM>, the resulting arc(s) can be redirected by the magnetic fields generated by the magnets 170A toward one of the pair of side walls <NUM> to extinguish the arc(s).

<FIG> is a top-sectional view of a portion of an arc chute <NUM> in accordance with a third embodiment. The arc chute <NUM> can include the same or similar components as the arc chute <NUM> of <FIG>, except that a back insulator 150B can include at least one horizontal vent opening <NUM> and can support a plurality of horizontal magnets 170B in respective pockets 154B as shown in <FIG>. The horizontal vent opening(s) <NUM> (e.g., in <FIG>) can facilitate the flow of gases out from the open area <NUM>. The arc chute <NUM> can also include additional front/side insulators (e.g., <NUM> in <FIG> or others described herein) arranged on an outer surface of the side walls <NUM>.

As shown in <FIG>, the magnets 170B can generate a magnet field(s), as shown by the example field lines, around the arc chute <NUM> and across the open area <NUM>. In this example, a moving arm <NUM> of a circuit protective device can include or carry a moving electrical contact <NUM> (on an underside generally identified by broken lines). The moving arm <NUM> can pass through the open area <NUM> to engage or disengage the moving electrical contact <NUM> to and from another electrical contact <NUM> (e.g., a stationary contact), respectively, of the circuit protective device to enable or interrupt current flow, respectively. When arcing is produced in the open area <NUM>, the resulting arc(s) can be redirected by the magnetic fields generated by the magnet 170B toward one of the pair of side walls <NUM> to extinguish the arc(s).

Various examples of the back insulator is shown and described above with reference to <FIG>. It should, however, be understood that the back insulator can be formed as a single piece or multiple pieces, and can be configured with vent openings and magnets at desired positions on or along a back wall of the arc chute. For example, the back insulator can have vertical and/or horizontal vent openings and/or openings having other dimensions, shape or sizes. The vent openings for the back and other insulators can be arranged (or positioned) to correspond with the slots on the non-magnet body (e.g., <NUM>) or components of the arc chute. Other example insulator configurations, such as for the front/side insulators, will be described below with reference to the examples <FIG>. Furthermore, the side walls (or portions thereof) of the arc chute may be arranged against or in proximity to an outer side of the non-magnetic body according to the arc chute design.

<FIG> illustrate front and top views, respectively, of some of the components of an arc chute <NUM> in accordance with a fourth embodiment. The arc chute <NUM> can include the same or similar components as the arc chute <NUM> of <FIG>, except that a front insulator 160C can be arranged across a face (or front) of an open end of each side wall <NUM>. In this example, the body <NUM> includes a plurality of spaced-apart stacked plates <NUM>, which are received and held within the grooves or recesses <NUM> of the insulators 160C. The width of the front insulator 160C can correspond to a width of a respective arm 122C of the body <NUM> (e.g., a width of a face of an open end of the arm 122C).

<FIG> illustrate an example process for forming some of the components of an arc chute, such as the non-magnetic body and side walls, in accordance with various embodiments. As shown in <FIG>, each plate <NUM> of a non-magnetic body <NUM> can be formed with a plurality of stakes <NUM> on an outer side portion of the plate. As shown in <FIG>, plates <NUM> can then be staked to the side walls via the stakes <NUM>. As shown in <FIG>, the protruding portions of the stakes <NUM> can be spun to reduce or remove them from the arc chute assembly. Thereafter, the back insulator and magnet(s) can be incorporated into the assembly, which can then be inserted into a case/housing of a circuit protective device (e.g., circuit breaker, contactor, etc.) to create an area generally referred to as the arc chamber. The arc chamber can include arc chute, venting, and contact assembly. The process described above is simply provided as an example for forming an arc chute in accordance with one or more embodiments such as described herein.

<FIG> illustrate front and top views, respectively, of some of the components of an arc chute <NUM>, in accordance with a fifth embodiment. The arc chute <NUM> can include the same or similar components as the arc chute <NUM> of <FIG>, except that each front insulator 160D can be arranged across a face (or front) of an open end of a respective arm 122D of a non-magnetic body 110D, and the arc chute <NUM> can be designed with side gas channels <NUM> (e.g., a vertical recessed area or gap). In this example, the body 110D includes a plurality of spaced-apart stacked plates 120D, which are received and held within the grooves or recesses <NUM> of the insulators 160D. Extending portions (or moldings) <NUM> of the base 124D of the body 110D can extend beyond an outer side of the arms 122D, and the front insulators 160D can also extend beyond a face (or front) of an open end of each of the arms 122D. The extending portions <NUM> of the base 124D and the front insulators 160D together with an outer surface of the side walls 112D can form gas channels <NUM> for directing gas flow, such as for example toward a vent or venting components of a circuit protective device. In this example, the gas channels are formed by a combination of portions of the non-magnetic body 110D and the front insulators 160D along with the side walls 112D. The body 110D can have a π-shaped profile.

As further shown in <FIG>, the assembly of the arc chute <NUM> can be inserted into an arc chamber <NUM> of a circuit protective device. In operation, gases produced as a result of arcing can be directed toward an arc chamber vent <NUM> at a vent end (or back) of the arc chamber <NUM>. For example, some of the gases may be channeled from the side channels <NUM> through slots at the base of the body <NUM> to the vent <NUM>. The circulation of the gases can help to further extinguish arc by cooling the arc.

<FIG> illustrates an arc chute 1700A, which is an alternative example arc chute configuration to the arc chute <NUM> in <FIG>. As shown in <FIG>, side walls of the arc chute can be formed using side walls <NUM> of the arc chamber <NUM>.

<FIG> illustrates an arc chute 1700B, which is another alternative example arc chute configuration to the arc chute <NUM> in <FIG>. As shown in <FIG>, the non-magnetic body 110DB includes a recessed area on each outer side of the body, which together with the side wall (e.g., 112D) form side channels <NUM> for directing gas flow, such as for example toward a vent or venting components of a circuit protective device.

<FIG> illustrate front and top views, respectively, of some of the components of an arc chute <NUM> in accordance with a sixth embodiment. The arc chute <NUM> can include the same or similar components as the arc chute <NUM> of <FIG>, except that each side insulator 160E can be arranged on a side of a front of an open end of an arm 122E of a non-magnetic body 110E, and the arc chute <NUM> can be designed with a side gas channel <NUM> (e.g., a vertical recessed area or gap) on its side(s). In this example, the body 110E includes a plurality of spaced-apart stacked plates 120E, which are received and held within the grooves or recesses <NUM> of the insulators 160E. Extending portions (or moldings) <NUM> of the base 114E of the body 110E can extend beyond an outer side of the side walls 112E, and the side insulators 160E can also extend from an outer side of each of the arms 122E of the body 110E. The side insulators 160E and the extending portions <NUM> of the base 114E together with the side walls 112E can form gas channels <NUM> for directing gas flow, such as toward a vent or venting components of a circuit protective device. In this example, the body 110E can have a π-shaped profile.

In various examples described herein the gas channels can be formed by a combination of portions of the non-magnetic body and the front/side insulators (e.g., <FIG>), with a desired shape and direction. However, gas channel(s) can be formed by configuring a shape of the outer surface of the non-magnetic body (e.g., the stacked plates) with one or more vertical or horizontal recesses or gaps or a combination thereof on the outer surface of the walls (e.g., side and/or back walls), and/or through the use of additional insulators spaced-apart along an outer surface of the non-magnetic body. The arc chute design can also have tabs designed in as part of the metal plate and then staked or spun down to an insulator piece. The grooves (e.g., grooves, recesses, slots, etc.) of the insulators, which are configured to receive and support the plates of the non-magnetic body of the arc chute as well as separate and isolate the plates from each other, can be formed by stamping, cutting, molding or other manufacturing techniques. In general, the insulators and the non-magnet body can be joined using corresponding male and female parts (e.g., tongue and groove) for joining components, with the male part or the female part on the insulator or the non-magnetic body. Furthermore, each plate of the non-magnetic body can be formed as one piece or a plurality of pieces. For example, the pair of arms of each plate can be separate pieces, which are connected to the back insulator for support. In addition, the various components of the arc chute (e.g., non-magnetic body, insulator(s), side walls, back wall, etc.) can be connected together using various techniques, including but not limited to male/female connectors on the components, adhesives, stakes or staking, or other manufacturing techniques for joining components together.

The arc chute as described herein can be used with different types of circuit protective devices, including but not limited to a molded case circuit breaker (MCCB), miniature circuit breaker (MCB), unidirectional or bi-directional circuit breaker, and so forth. The size, shape, dimension and location of the various components or parts of the arc chute assembly (e.g., magnets, insulators, non-magnetic body, slots, openings, channels, recesses, recessed portions, recessed areas, etc.) can be varied to satisfy safety requirements, or according to the size or type of the circuit breakers or the particular application.

Claim 1:
An apparatus for extinguishing an arc, comprising:
a circuit breaker with a single-arm moving assembly, and
an arc chute (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, 1700A, 1700B, <NUM>) including:
a pair of opposing side walls (<NUM>, 112D, 112E, <NUM>) formed of an electrically insulating material;
a body (<NUM>, <NUM>, 110D, 110DB, 110E) arranged between the side walls, the body having an open area (<NUM>) and a plurality of slots (<NUM>) through which to facilitate gas flow;
a back wall (<NUM>) arranged on a back side of the body, the back wall including at least one first insulator (<NUM>, 150A, 150B),
characterized in that
the body (<NUM>, <NUM>, 110D, 110DB, 110E) is a non-magnetic body,
the back wall (<NUM>) includes at least one magnet (<NUM>, 170A, 170B),
the at least one first insulator (<NUM>, 150A, 150B) being arranged between the at least one magnet (<NUM>, 170A, 170B) and the open area and configured to electrically isolate the magnet from the non-magnetic body, the magnet generating a magnetic field to redirect an arc in the open area (<NUM>) toward one of the side walls (<NUM>, 112D, 112E, <NUM>) and to create turbulence to cool to the arc.