The present invention relates to circuit breakers.
Circuit breakers are one of a variety of overcurrent protection devices used for circuit protection and isolation. The circuit breaker provides electrical protection whenever an electric abnormality occurs. In a typical circuit breaker, current enters the system from a power line and passes through a line conductor to a stationary contact fixed on the line conductor, then to a movable contact. The movable contact is fixedly attached to a pivoting arm. As long as the stationary and movable contacts are in physical contact, current passes from the stationary contact to the movable contact and out of the circuit breaker to down-line electrical devices.
In the event of an overcurrent condition (e.g., a short circuit), extremely high electromagnetic forces can be generated. The electromagnetic forces repel the movable contact away from the stationary contact. Because the movable contact is fixedly attached to the rotating arm, the arm pivots and physically separates the stationary and movable contacts, thus tripping the circuit. Upon separation of the contacts and blowing open the circuit, an arcing condition occurs. The breaker's trip unit will trip the breaker which will cause the contacts to separate.
Embodiments of the invention are directed to circuit breakers with moving contacts having heel-toe action which are configured to direct arcing across a small portion of a stationary contact surface to arc chutes to thereby alleviate deterioration due to arcing and improve conductivity of a major portion of the stationary contact and moving contact surface over time.
Embodiments of the invention are directed to circuit breakers that include a moveable contact arm. The contact arm has first and second cooperating arm members coupled together. The first arm member engages a pivotable handle and the second arm member comprising an electrical contact. The second arm member can move inward and outward relative to the first arm member.
A lower end portion of the first arm member can be pivotably attached to an upper end portion of the second arm member.
The circuit breaker can include a stationary contact and an arc chute. Only a toe portion of the second arm member last engages a lower edge portion of a stationary contact prior to separation from the stationary contact when the arm moves toward an “OFF” position and/or in an opening position to thereby direct arcing into the arc chute and avoid arcing across a surface of the stationary contact above the lower edge portion.
Adjacent ends of the first and second cooperating arm members can be coupled together in a manner that allows an upper end of the second arm member to move inward and outward and up and down relative to a lower end portion of the upper arm member.
The circuit breaker can include a sleeve affixed to a lower end portion of the first arm member. The sleeve can have a slot. The second arm member can also include a slot. The slot of the sleeve and the slot of the second arm member can be aligned so as to allow a pin to extend therethrough and allow the pin to travel inward, outward, upward and downward to place the second arm member in different positions.
The first arm member can hold a lower end of mechanism spring and can have a curvilinear receiving pocket that faces the upper end of the second arm member. The mechanism spring and/or another spring attached to the first arm member can apply a downwardly extending first force vector to the second arm member. The second arm member can engage a spring configured to apply an upwardly extending second force vector in a direction opposing the first force vector.
The spring that applies the second force vector can extend off a back surface of the first arm member down about a back surface of the second arm member.
An upper segment of the second arm member can be spaced apart from the lower segment of the first arm member at the coupling of the first and second arm members.
The second arm member can include an upwardly extending slot that is aligned with a cooperating slot in a sleeve attached to the first arm member or to a slot in the first arm member. A pin can extend through the slots and the pin in the cooperating slots allows the second arm member to translate relative to the first arm member.
The circuit breaker can include a spring that is attached to and extends below the first arm member behind an upper end portion of the second member to force the second arm member to rotate forward.
The circuit breaker can include a mechanism spring held by a lower end of the first arm member. The first arm member can include a knee that resides above the lower end of the first arm member that faces the mechanism spring.
The circuit breaker can include a mechanism spring held by a lower end segment of the first arm member. The lower end segment of the arm member can have a smaller width than a width of the second arm member adjacent thereto and resides spaced apart a distance from an adjacent underlying portion of the second arm member.
Other embodiments are directed to methods of operating a circuit breaker. The methods include: (i) placing only a toe segment of a moving contact against a stationary contact at a lower edge portion of the stationary contact immediately prior to an arcing action; and (ii) directing all arcing down into an adjacent arc chute providing an arc-free contact surfaces above the toe segment of the moving contact and above the lower edge portion of the stationary contact.
The placing step can be carried out by using a moveable contact arm having first and second arm members coupled together, the placing comprises translating the second arm member relative to the first arm member.
The placing step can be carried out by using a moveable contact arm having first and second arm members pivotably coupled together by pivoting the second arm member relative to the first arm member.
The placing step can be carried out by using a moveable contact arm having first and second arm members coupled together with at least one pin and cooperating slots. The pin can travel in the slots allowing the second arm member to travel through different positions.
The placing step can be carried out using a moveable contact arm having an upper arm member coupled to a lower arm member and applying spring force vectors to only the lower arm member that (i) push an inner facing surface of the lower arm member downward and (ii) push an outer facing surface of the lower arm member inward.
The method can include applying a first spring force against a lower arm member of a moveable contact arm to rotate the lower arm member clockwise when opening and applying a second spring force using a main mechanism spring attached to an upper arm member of the moveable contact arm, the lower arm member configured to move inward, outward and up and down relative to the upper arm member whereby the second spring force is stronger than the first spring force so as to rock the lower arm member counter clockwise once in an “ON” position.
Still other embodiments are directed to circuit breakers that include a housing, a pivotable handle held by the housing and a moveable contact arm held in the housing. The arm has first and second cooperating arm members. The first arm member engages the pivotable handle and the second arm member includes an electrical contact and is configured to be able to translate inward and outward and/or pivot relative to the first arm member. The circuit breaker also includes a stationary contact in the housing configured to engage the electrical contact of the second arm member. At least one of the stationary contact or the second arm electrical contact includes silver in an amount between about 35, and 97%.
An upper portion of the second arm member can be pivotably attached to a lower portion of the first arm member. Only a toe portion of the second arm member electrical contact engages only a lower edge portion the stationary contact when the arm moves toward an OFF position and/or in an opening position to thereby direct arcing into the arc chute and avoid arcing across a surface of the stationary contact above the lower edge portion.
Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.
It is noted that aspects of the invention described with respect to one embodiment, may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below.
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which illustrative embodiments of the invention are shown. Like numbers refer to like elements and different embodiments of like elements can be designated using a different number of superscript indicator apostrophes (e.g., 40, 40′, 40″, 40′″).
In the drawings, the relative sizes of regions or features may be exaggerated for clarity. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The term “Fig.” (whether in all capital letters or not) is used interchangeably with the word “Figure” as an abbreviation thereof in the specification and drawings. In the figures, certain layers, components or features may be exaggerated for clarity, and broken lines illustrate optional features or operations unless specified otherwise. In addition, the sequence of operations (or steps) is not limited to the order presented in the claims unless specifically indicated otherwise.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.
Spatially relative terms, such as “beneath”, “below”, “bottom”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass orientations of above, below and behind. The device may be otherwise oriented (rotated 90° or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The term “about” refers to numbers in a range of +/−20% of the noted value.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
The term “non-ferromagnetic” means that the noted component is substantially free of ferromagnetic materials so as to be suitable for use in the arc chamber (non-disruptive to the magnetic circuit) as will be known to those of skill in the art.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Turning now to the figures,
As shown in
The handle 15 can be associated with a disconnect operator (e.g., an operating handle) connected to an assembly for opening and closing separable main contacts in a circuit breaker 10 or for turning power “ON” and “OFF” using a switch associated with a fuse. The circuit breaker 10 can be for a motor starter unit or feeder unit, for example. It is noted that not all circuit breakers 10 require a “TRIP” position (e.g., fused disconnect switches), so in some embodiments, the arm 25 and handle 15 can include only two operative positions, “ON”, “OFF,” rather than “ON,” “OFF” and “TRIP” positions.
Turning back to
Embodiments of the invention are configured to keep the arc at the “toe” of the contact 25t, which is at the bottom of the breaker, close to the arc chute 75 (
During endurance testing per UL 489, the arm 20 rapidly repetitively moves through its operative positions. Operational requirements from UL's “X” Program called “Overload” currently requires a breaker to be toggled 50, times at six (6) times rated current. For a 150, Amp breaker, the six (6) times test current is 900, Amps, which is arcing the contacts 25, 125 fifty (50) times. Afterwards, a temperature rise test is performed and the temperature rise cannot exceed 50, degrees C. It is contemplated that the new cooperating arm members 21, 22 will meet the Overload temperature rise requirement, and, indeed, be able to operate at a maximum temperature rise defined by the noted UL Overload test of 50, degrees C.
The effectiveness of contact performance is typically directly proportional to the amount of silver in the contacts, which can be an expensive component of a breaker 10. Embodiments of the invention allow a reduction in the percentage of silver in the contacts 25, 125, potentially allowing for a substantial cost reduction. Today some contacts are 50% Ag, although 70% and up to 97% may be useful. It is contemplated that the contacts can have Ag in a range as low as about 35%. Embodiments of the invention can have contacts with Ag content between about 35% and 97%, including about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, and about 90%.
In some embodiments, in the “ON” position (
The sleeve 30, where used, can be pinned, screwed, nailed, riveted (27,
Referring to
The ramp 21r, can be continuously in contact with the upper part of the lower arm 22t. The smallest gap size 24 for the hook arm 21h, may be such as to provide at least about a 0.020, inch clearance, typically between about 0.020, and 0.050, inches to provide for any tolerance stack up during assembly.
As shown in
The lower/second arm member 22 can have a shunt attachment member 61 that engages a shunt 60 (
Still referring to
The lower resilient member or spring 32 (
A resilient member or spring 37 for transmitting the force vector Fl can reside in the gap space 24 (
The heel and toe 25h,, 25t, can each have a small contact area or point that is tangent T to a line extending off a bottom edge 22b, of the second arm member 22. Particularly for the opening configuration (
Referring to
The handle 15 can include an external portion 15e, (
The circuit breaker 10 can also include one or more of a magnet 135, a load collar 38, a load terminal 39, a bimetal member 43, an armature 44, a shunt bracket 47, a spring clip 50, a cradle 55 and frame 57. The circuit breaker 10 can have alternate configurations and components.
The arm 20 and handle 15 can have defined operative positions, “OFF,” “ON” and (optionally) “TRIP”. The movements can be over a desired handle angulation, typically between about 45, degrees to about 90, degrees, more typically about 90, degrees between the “OFF” and “ON” positions with the “TRIP” position between the “OFF” and “ON”. In the “ON” position, the arm 20 places the moveable contact 25 in abutting contact with the stationary contact 125. In the “OFF” position, the arm 20 rotates to move the moveable contact 25 away from the stationary contact 125. In the “TRIP” position, the arm 20 also positions the moveable contact 25 away from the stationary contact 125, typically a distance greater than the spaced apart distance of the two contacts 25, 125 in the “OFF” position.
Typically, in use, the face F (
In some embodiments, the circuit breakers 10 can be DC circuit breakers, AC circuit breakers, or both AC (alternating current) and DC (direct current) circuit breakers.
The circuit breakers 10 can be rated for voltages between about 1V to about 5000 volts (V) DC and/or may have current ratings from about 15, to about 2,500, Amps. The circuit breakers 10 may be high-rated miniature circuit breakers, e.g., above about 70A in a compact package. However, it is contemplated that the circuit breakers 10 and components thereof can be used for any voltage, current ranges and are not limited to any particular application as the circuit breakers can be used for a broad range of different uses.
The circuit breakers 10 can be molded case circuit breakers (MCCB)s. MCCBs are well known. See, e.g., U.S. Pat. Nos. 4,503,408, 4,736,174, 4,786,885,, and 5,117,211,, the contents of which are hereby incorporated by reference as if recited in full herein.
The circuit breakers 10 can be a bi-directional DC MCCB. See, e.g., U.S. Pat. No. 8,222,983,, the content of which is hereby incorporated by reference as if recited in full herein. The DC MCCBs can be suitable for many uses such as data center, photovoltaic, and electric vehicle applications.
As is known to those of skill in the art, Eaton Corporation has introduced a line of MCCBs designed for commercial and utility scale photovoltaic (PV) systems. Used in solar combiner and inverter applications, Eaton PVGard™ circuit breakers are rated up to 600, Amp at 1000, Vdc and can meet or exceed industry standards such as UL 489B, which requires rigorous testing to verify circuit protection that meets the specific requirements of PV systems. However, it is contemplated that the circuit breakers 10 can be used for various applications with corresponding voltage capacity/rating. In some particular embodiments, the circuit breaker 10 can be a high-rating miniature circuit breaker.
The pivoting can be carried out to move adjacent ends of the first and second cooperating arm members closer together and farther apart over a sequence of operational positions between ON and OFF (block 205).
The first and second arm members can be made of different conductive metallic materials (block 202).
The second arm member can have opposing longitudinally spaced apart ends, the first end has the contact and pivots toward and away from the stationary contact and the second end is attached directly or indirectly to the first arm member (block 208).
The first and second arm members can be connected with a sleeve with an elongate slot attached to adjacent end portions of the first and second arm members. The method can include moving the second arm member up and down while a pin attached to the sleeve and second arm member travels in the slot (block 212).
Only the toe (adjacent the lower edge of the contact) can engage the stationary contact when the arm rotates toward an OFF position/in an opening position to thereby direct arcing directly into the arc chutes avoiding virgin contact surfaces thereabove (block 215).
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.
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Entry |
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Non-final Office Action corresponding to U.S. Appl. No. 14/698,192 (16 pages) (mailed Aug. 11, 2016). |
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20160163482 A1 | Jun 2016 | US |