PROTECTIVE ELECTRICAL DEVICE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to electrical wiring devices, and particularly to electrical wiring devices that include electric circuit protective features.

2. Technical Background

The average consumer is so used to having electric power at his beckon call, that he often forgets, or does not know, how that electric power is delivered to him. The terms “electrical wiring device” or “electrical circuit” are thus very often abstractions to the typical consumer. As such, it may be useful to provide a brief review of the terminology that is used to describe the technologies related to the delivery of electric power within a structure or a residence.

AC electric power service provided by the power utility is usually terminated by a breaker panel located within the residence. Very often the breaker panel is disposed in the basement of the structure if it has one. The breaker panel distributes the electric power to various branch circuits throughout the structure such that each branch circuit is monitored and controlled by a circuit breaker. If the circuit breaker detects a fault condition it will trip the breaker to interrupt the delivery of power to that circuit. Moreover, the consumer may manually actuate the breaker switch to interrupt the delivery of power to that circuit. The breaker switches may be rated at 20 A or 15 A depending on the nature of the branch circuit.

The backbone of a single phase branch circuit typically includes a cable that has a black (hot) wire, a white (neutral) wire and a green (ground) wire. In some cases, only two wires (hot and neutral) are employed. An additional hot wire is required for each additional phase such that a two phase circuit may include four wires and a three phase circuit may include five wires. The conventional method for installing electrical circuits includes a “rough-in” installation phase and a finish installation phase. In the rough-in phase, conduit or cable is disposed throughout the structure in accordance with the building plans. Junction boxes are installed at appropriate locations to house electrical connection points where two or more conductors can be spliced together. Device boxes are installed throughout the structure where electrical service is desired. After the boxes are placed, the electrical wires are pulled through the conduits (if provided) and all of the circuits are bonded such that the neutral conductors are connected to ground at or near the circuit breaker.

The electrical wiring in a branch electric circuit typically interconnects one or more electrical wiring devices. One or more electrical wiring devices may be mounted to a device box depending on the size of the device box. A single-gang device box typically accommodates one electrical wiring device; a two-gang device box will typically accommodate two electrical wiring devices, and so on and so forth. An electrical wiring device provides the consumer with a point of access to electrical service. For example, a receptacle outlet provides power to a portable device when the device's corded power plug is inserted into an energized receptacle. Once an electrical wiring device is installed inside the device box, a cover plate is disposed over the electrical wiring device to “complete the electrical enclosure” such that individuals are not exposed to “hot” electrical wiring after the electrical power is turned ON.

From a structural standpoint, an electrical wiring device is disposed within an electrically non-conductive housing, and nowadays that non-conductive material is usually made from a hard plastic material. A set of line terminals, a set of load terminals and often a ground connection are provided at the exterior of the electrical wiring device and are connected to electrical components or conductors disposed in the interior of the device. The “line terminals” of an electrical wiring device refers to the terminals that connect the wiring device to conductive wires from the breaker panel. The “load terminals” or the “feed-through load terminals” are connected to downstream wiring that is configured to propagate AC power to one or more downstream electrical loads. The term “receptacle load terminals” refers to a receptacle outlet that provides power to a portable load when a corded power plug is inserted therein. A load, of course, refers to an appliance, a lighting device, or some other kind of device that consumes electrical power during operation.

Certain types of electrical faults are known to occur in branch electric circuits and electrical wiring systems. These faults represent serious safety issues that may result in fire, shock or electrocution if not addressed properly. Electric circuit protection devices are deployed in the branch electric circuits to prevent the consumer from being shocked or electrocuted when such faults occur. These protective devices usually include a circuit interrupter disposed between the line terminals and the load terminals. The circuit interrupter provides power to the load terminals under normal conditions; however, when the protective device detects a fault condition in the load circuit, it will trip the circuit breaker to interrupt electrical connectivity between the line terminals and the load terminals. There are many types of electric circuit protection devices including ground fault circuit interrupters (GFCIs), arc fault circuit interrupters (AFCIs), transient voltage surge suppressors (TVSSs), or surge protective devices (SPDs). This list includes representative examples and is not meant to be exhaustive and a single device may be configured to perform one or more of these functions (e.g., a combination AFCI/GFCI).

There are several drawbacks associated with conventional installation methods and conventional protective electrical wiring devices. Conventional protective electrical wiring devices often do not make efficient use of space. In addition, mounting the wiring device's ground strap to the device box is tedious, time consuming, and therefore costly. The same can be said of mounting the cover plate to the electrical wiring device. Moreover, in multi-gang installations, the finished look is often ragged because the plurality of electrical devices and their respective cover plates are typically not in alignment. This misalignment can be, and very often is, in all three dimensions. Retrofitting an electrical installation can also be problematic from the standpoint of the finished look because the device box, or an old work box, may not be precisely aligned to the plane of the wall surface. This is especially true if the wall surface itself is uneven. After remodeling a space, homeowners often seek to replace an existing wall plate with one that better matches the new décor. Thus, a homeowner may inadvisably remove the faceplate cover from an energized wiring device and inadvertently become exposed to a shock hazard from the “hot” electrical wiring.

What is needed therefore is a protective electrical wiring device system that addresses the drawbacks articulated above. In particular, what is needed is a protective electrical wiring device that may be employed in a number of different form factors without having to modify the internal electro-mechanical configuration of the device. Stated differently, a protective device is needed that can be configured in a conventional form factor or in another form factor suitable for use in a modular framing system such that it does not require fasteners to be securely installed within the device box.

SUMMARY OF THE INVENTION

The present invention addresses the needs described above by providing a protective electrical wiring device system that addresses the drawbacks articulated above. The protective electrical wiring device of the present invention may be employed in a number of different form factors without having to modify the internal electro-mechanical configuration of the device. In other words, the protective device of the present invention can be configured in a conventional form factor or in a form factor suitable for use in a modular framing system such that it does not require fasteners to be securely installed within the device box.

Generally in one aspect, an electrical wiring device includes: a housing assembly including a cover assembly and a back body member, the cover assembly including a plurality of receptacle openings, the housing assembly further including a plurality of line terminals and a plurality of feed-through load terminals, the housing assembly also including a plurality of receptacle load terminals substantially aligned with the plurality of receptacle openings; a fault protection circuit disposed in the back body and substantially disposed on at least one printed circuit board (PCB), the fault protection circuit being configured to provide a fault detection stimulus in response to detecting at least one type of predetermined fault condition, the fault detection stimulus decoupling a reset pin from a latching element, the reset pin being coupled to the latching element in response to a reset stimulus; and a circuit interrupter disposed inside the housing, the circuit interrupter including a latch block assembly configured to accommodate the reset pin and the latching element, the latch block being moveable between a first state in response to the reset stimulus and a second state in response to the fault detection stimulus, wherein the latch block assembly comprises an upper latch block, wherein the reset pin is positioned through the upper latch block, and the upper latch block is configured to drive the circuit interrupter only in a single direction, the driving in the single direction serving to decouple the plurality of line terminals, the plurality of feed-through load terminals and the plurality of receptacle load terminals to the second state.

According to an embodiment, the latch block assembly further includes a central latch block portion configured to accommodate the reset pin and the latching element, the central latch block portion including an open side.

According to an embodiment, the circuit interrupter further includes at least one set of a plurality of contact sets configured to close in the first state and open in the second state, at least one of the plurality of contact sets being configured to decouple at least a portion of the fault protection circuit assembly from one line terminal of the plurality of line terminals, in the second state.

According to an embodiment, the portion of the fault protection circuit assembly includes a solenoid configured to effect the second state when the at least one type of predetermined fault condition is detected.

According to an embodiment, the device further includes a switch including a switch throw element coupled between the latch block assembly and a moveable contact assembly, the switch throw element including a coil spring at least partially disposed on a second side of the at least one PCB, the coil spring being configured to drive the movable contact assembly so that the movable contact assembly engages a fixed contact assembly to close the auxiliary switch, the latch block assembly being configured to drive the switch throw element to open the moveable contact assembly and a fixed contact assembly.

According to an embodiment, the switch is configured to decouple at least a portion of the fault protection circuit assembly from the plurality of line terminals in the second state.

According to an embodiment, the coil spring is constrained between an interior surface of the back body and the moveable contact assembly.

According to an embodiment, the interior surface includes a post structure.

According to an embodiment, the device further includes a frame configured to be mounted to a device wall box, the frame including a first edge formed around a peripheral portion of the frame, the first edge being configured to overlay a structural surface disposed around the device wall box, the frame assembly further including a frame opening corresponding to at least one gang opening, the frame opening substantially defining a second edge configured to extend inwardly toward the device wall box interior such that the frame opening provides sole access to the device wall box interior, the housing being configured to be coupled within the frame opening to complete a system enclosure such that the device wall box interior is substantially inaccessible.

According to an embodiment, the device further includes an aesthetic overlay configured to be removably coupled to the frame assembly, the aesthetic overlay including an overlay opening configured to provide access to at least a portion of the cover assembly.

According to an embodiment, the circuit interrupter includes a plurality of contact sets configured to close in the first state and open in the second state, the upper latch block being substantially disposed between the plurality of contact sets and a user accessible surface of the cover assembly.

According to an embodiment, the latch block assembly further includes a lower latch block configured to drive the circuit interrupter only in a second direction to couple the plurality of line terminals, the plurality of feed-through load terminals and the plurality of receptacle load terminals to the second state.

According to an embodiment, the circuit interrupter includes a plurality of contact sets configured to close in the first state and open in the second state, and the lower latch block is substantially disposed between the plurality of contact sets and a major rear surface of the back body member.

According to an embodiment, the circuit interrupter further includes an auxiliary switch configured to decouple a trip solenoid in series with a control thyristor from a line terminal of the plurality of line terminals in the second state.

According to an embodiment, the plurality of receptacle load terminals include a plurality of fixed contacts that become connected to the plurality of line terminals and the plurality of feed-through load terminals in the first state and electrically isolated from the plurality of line terminals and the plurality of feed-through load terminals in the second state.

According to an embodiment, the latch block assembly further includes a central axis positioned through a central portion of the latch block assembly, and wherein the upper latch block further includes at least one set of two breaker arms, each breaker arm extending in a plane that is substantially perpendicular to the central axis.

According to an embodiment, the latch block assembly further includes a central axis positioned through a central portion of the latch block assembly, and wherein the lower latch block further includes a set of two lifter arms, each lifter arm extending in a plane that is substantially perpendicular to the central axis.

According to an embodiment, the reset pin is positioned through a reset pin aperture in the upper latch block.

Generally in another aspect, a circuit interrupting device includes: a first pair of electrical conductors including a phase and neutral, the first pair of electrical conductors adapted to electrically connect to a source of electric current; a second pair of electrical conductors including a phase and neutral; a third pair of electrical conductors including a phase and neutral, wherein the first, second, and third pairs of electrical conductors are electrically isolated from each other and positioned to electrically connect to at least one user accessible receptacle; a reset assembly comprising a reset pin; a latch block assembly comprising an upper latch block, wherein the reset pin is positioned through the upper latch block, and the upper latch block is configured to move between a first state which provides electrical continuity between the first pair of electrical conductors and at least one of the second and third pairs of electrical conductors and a second state where electrical continuity between at least two of the pairs of electrical conductors has been broken in response to a driving force applied by the upper latch block only in a single direction; and at least one break spring coupled to the upper latch block and configured to drive the upper latch block from the first state to the second state upon the occurrence of a predetermined fault condition.

According to an embodiment, the device further includes a housing including a front cover and a back body member having a user accessible surface; and a circuit interrupter including a plurality of contact sets configured to close in the first state and open in the second state, the upper latch block being substantially disposed between the plurality of contact sets and a user accessible surface of the front cover.

According to an embodiment, the device further includes at least one make spring, where the latch block assembly further includes a lower latch block, and the at least one make spring being configured to drive the lower latch block from the second state to the first state after resolution of the predetermined fault condition.

According to an embodiment, the device further includes a housing including a front cover and a back body member, the back body member having a major rear surface; and a circuit interrupter including a plurality of contact sets configured to close in the first state and open in the second state, the lower latch block being substantially disposed between the plurality of contact sets and the major rear surface.

According to an embodiment, the reset pin is configured to movably reorient the lower latch block to the first state to reestablish electrical continuity between the pairs of electrical conductors after resolution of the predetermined fault condition.

According to an embodiment, the reset assembly further includes a reset button and a latch, the reset assembly configured to receive a reset stimulus serving to couple the reset assembly to the latch in the first state.

According to an embodiment, each conductor among the plurality of first pair of electrical conductors and the plurality of second pair of electrical conductors includes a cantilever member moveable between the first state and second state.

According to an embodiment, the cantilever members associated with the second pair of electrical conductors are adapted to electrically connect to the plurality of third pair of electrical conductors.

According to an embodiment, the plurality of third pair of electrical conductors includes a plurality of fixed electrical contacts connected to the at least one user accessible receptacle, the cantilever members connecting to the plurality of fixed electrical contacts in the first state.

According to an embodiment, the latch block assembly further includes a central latch block portion configured to accommodate a reset pin and a latching element, the central latch block portion including an open side.

According to an embodiment, the latch block assembly further includes a lower latch block.

According to an embodiment, the lower latch block is coupled to a make spring and configured to move between the first state and the second state, the make spring being configured to drive the lower latch block from the second state to the first state after resolution of the predetermined fault condition.

According to an embodiment, the reset pin is positioned through a reset pin aperture in the upper latch block.

Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a protective wiring system in accordance with one embodiment of the present invention;

FIGS. 2A and 2B are perspective views of the frame member depicted in FIG. 1;

FIG. 3 is a perspective view of the protective wiring device depicted in FIG. 1;

FIG. 4 is a perspective view of a protective wiring device in accordance with an alternate embodiment of the present invention;

FIG. 5 is a perspective view of the protective wiring device depicted in FIG. 3 with the front cover assembly removed;

FIG. 6 is a first perspective view of the protective wiring device depicted in FIG. 3 with the housing assembly removed;

FIG. 7 is a second perspective view of the protective wiring device depicted in FIG. 3 with the housing assembly removed;

FIG. 8 is a perspective view of the protective wiring device depicted in FIG. 3 with the housing assembly and the separator cap removed;

FIG. 9 is a perspective view of the protective wiring device depicted in FIG. 3 with the housing assembly, separator and separator cap removed;

FIG. 10 is a perspective view of a protective wiring system in accordance with another embodiment of the present invention;

FIG. 11 is a perspective view of a protective wiring device depicted in FIG. 10;

FIG. 12 is a perspective view of the protective wiring device depicted in FIG. 10 with the front cover assembly removed;

FIG. 13 is a perspective view of the protective wiring device depicted in FIG. 10 with the housing assembly and the separator cap removed;

FIG. 14 is a perspective view of the protective wiring device depicted in FIG. 10 with the housing assembly, separator and separator cap removed;

FIG. 15 is another perspective view of the protective wiring device depicted in FIG. 10 with the housing assembly, separator and separator cap removed;

FIG. 16 is a rear perspective view of the protective wiring device depicted in FIG. 10;

FIG. 17 is a perspective view of the printed circuit board assembly of the protective wiring device depicted in FIG. 10;

FIG. 18 is a perspective view of the lower latch block assembly depicted in FIG. 17;

FIG. 19 is a perspective view of the latch block assembly in accordance with another embodiment of the present invention;

FIG. 20 is a perspective view of the lower latch block portion of the latch block assembly depicted in FIG. 19;

FIG. 21 is a perspective view of a protective wiring device in accordance with yet another embodiment of the present invention;

FIG. 22 is a schematic view of a ground fault circuit interrupter in accordance with embodiments of the present invention;

FIG. 23 is a schematic view of a ground fault circuit interrupter in accordance with alternate embodiments of the present invention; and

FIG. 24 is a schematic view of an arc fault circuit interrupter in accordance with yet other alternate embodiments of the present invention.

DETAILED DESCRIPTION

Reference will now be made in detail to the present exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. An exemplary embodiment of the protective device of the present invention is shown in FIG. 1, and is designated generally throughout by reference numeral 10.

As embodied herein and depicted in FIG. 1, a perspective view of a protective wiring system 100 in accordance with an embodiment of the present invention is disclosed. System 100 includes a protective wiring device 10 disposed within frame member 90. The protective device 10 includes a front cover assembly 12 that is accessible via an opening 90-13 of the frame. The back body portion 14 of the device 10 is snapped into the frame 90 such that it is positioned within the device box (not shown). The back body portion 14 is inaccessible to the user once it is coupled to the frame 90. Thus, one of the features of this embodiment of the present invention is that the frame member 90 is configured to “complete the electrical enclosure” when a modular electrical device (such as protective device 10) is properly installed within the frame 90. The frame member 90 prevents individuals from being exposed to hot electrical wiring in the device box.

Referring to FIGS. 2A and 2B, perspective views of the frame member 90 depicted in FIG. 1 are disclosed. FIG. 2A is directed to the rear side 90-2 of the frame member 90, whereas FIG. 2B is directed to the front side 90-1 of the frame member 90. With respect to “completing the electrical enclosure” when a modular electrical device is properly installed within the frame, the modular device is snapped into frame opening 90-13 and completely fills the opening 90-13. In conventional designs, a conventional wall plate is used to complete the enclosure. As stated above, the present invention thus prevents individuals from being exposed to hot electrical wiring in the device box before a wall plate is installed.

Note that a frame enclosure lip 90-5 is formed around the outer perimeter of the frame. The frame enclosure lip 90-5 is configured to be disposed over, and abut, the wall surface 1 (not shown in this view). The edge of a properly installed wall box would thus seldom, if ever; touch the rear surface of the frame because of the frame enclosure lip 90-5 provides separation between the frame and the wall surface. This is true even when old work boxes are deployed. Old work boxes, of course, have flanges that mount to the outer surface of the sheet rock. One of the functions of the frame enclosure lip 90-5 is therefore to avoid interference with these flanges such that the frame 90 does contact the wall surface 1.

The frame opening 90-13 is sized to accommodate three device modules. Stated differently, the frame opening can accommodate three one-module devices, a one module device and a two module device, or a three module device. The frame 90 may be equipped with modular alignment connectors that allow the electrical enclosure to be completed with a single two-module sized device. In this case, the device is disposed between two alignment connectors that together take up one module's worth of space within opening 90-13. Reference is made to U.S. patent application Ser. No. 13/680,675, which is incorporated herein by reference as though fully set forth in its entirety, for a more detailed explanation of the frame member 90.

The frame opening 90-13 has edge portions that mate with the snap elements 14-4 (see FIG. 5) formed in the back body of the protective wiring device 10 shown herein. The device depicted in FIG. 1, for example, is equipped with a three-module sized back body 14 and a two module front cover 12. Thus, the device 10 does not require the use of any modular alignment connectors. Again, once the electrical wiring device is installed within the frame opening 90-13, the enclosure is completed. An interior serrated lip 90-6 extends from both side portions of the frame device opening 90-13 and adjoins a connector landing element 90-7 disposed at either end of the frame opening 90-13. The interior serrated lips 90-6 and the connector landing elements 90-7 extend perpendicularly around the entire frame opening 90-13 to form a rim or skirt that is inserted into the device box during installation. Accordingly, the region between the outer enclosure lip 90-5 and the interior rim (i.e., serrated lips 90-6 and landing 90-7) is disposed over the wall surface 1. Once the wall box fasteners 90-10 are inserted into the fastener slots 90-12 and tightened, the only way of accessing the interior of the device box is via the frame opening 90-13. However, the frame opening 90-13 is completely occupied by the protective wiring device 10 and thus the interior of the device box is inaccessible.

Referring to FIG. 3, a perspective view of the protective wiring device 10 depicted in FIG. 1 is disclosed. Again, the protective device 10 includes a two module front cover 12 and a three module back body 14. The front cover 12 includes stepped portions 12-1 that are recessed relative to the raised center portion 12-2 formed in front cover 12. The portion of the front cover 12 that includes the receptacle openings 16, test button 15 and reset button 17 is framed by an aesthetic overlay (not shown). Note that the reset button and the test button are diagonally disposed with respect to each other. Stated differently, a substantially square area 11 is formed by extending imaginary horizontal and imaginary vertical lines from the outer edges of the test and reset buttons such that the test and reset buttons are disposed in opposite corners of the substantially square area 11. The term “imaginary lines” means that the lines are not visible on the device but are merely used to define the meaning of the term “square area” herein. The stepped or recessed cover portions 12-1 are hidden behind the aesthetic overlay when it is mounted to the frame to give the assembly a finished and aesthetically pleasing appearance. As described in U.S. patent application Ser. No. 13/680,675, which is incorporated herein by reference as though fully set forth in its entirety, the frame 90 is configured to retain an aesthetic overlay by way of ratcheting snap elements 90-3, 90-3′ and 90-4.

Note that the reset button 17 includes a visual indicator lens 17-1 formed therein. The lens 17-1 is in optical communication with a light source disposed within the housing of device 10. The nature of the indicator is described below in the discussion of the various schematics. The back body is shown herein to include snap elements 14-1 which are configured to snap into and mate with the serrated edges 90-60 of the frame opening 90-13.

Referring to FIG. 4, a perspective view of a protective wiring device in accordance with an alternate embodiment of the present invention is disclosed. Note that in the various views provided herein, like reference numerals refer to identical or functionally-similar elements. The device of FIG. 3 is a 15 A device, whereas the device 10 of FIG. 4 is a 20 A device, as shown by the neutral openings 16-2′ in FIG. 4. Otherwise, both devices are similar. FIG. 4 also shows self-grounding contact 14-3, which is also employed in the 15 A device of FIG. 3 (but not shown). Alternatively, the ground connection may be made via a ground wire 14-3′. Device 10 also includes line terminals 14-1 which are configured to terminate the wiring that extends back to the breaker panel. Load terminals 14-2 (not shown in this view) are disposed at the opposite end of the device 10.

Referring to FIG. 5, a perspective view of the protective wiring device depicted in FIG. 3 (with the front cover assembly removed) is shown. The device 10 includes a separator cap 20 that is disposed under the front cover 12. The separator cap 20 is fabricated from a non-conductive material and is configured to accommodate the shutter assemblies 22 and the ground strap 24. The test button 15 and the reset button 17 are connected to components that are disposed under the separator cap 20. The ground strap 24 includes receptacle ground contacts 24-1 that are aligned with the ground prong openings 16-3 formed in the front cover 12. Thus, when a corded plug is inserted into the receptacle openings 16, the ground prong portion extends through opening 16-3 to mate with the ground contacts 24-1. The movistor MOV1 is also seen in this view; MOV1 is connected to between the line terminals 14-1. Reference is made to U.S. patent application Ser. No. 13/487,547, filed Jun. 4, 2012 which is incorporated herein by reference as though fully set forth in its entirety, for a more detailed explanation of the shutter assemblies 22.

Referring to FIG. 6, a first perspective view of the protective wiring device depicted in FIG. 3 is disclosed. This view shows the latch block assembly 50, the hot circuit interrupter 60-1, and illustrates the underside of the PCB 40 with the housing assembly removed.

Two different contact embodiments are shown at the same time for purposes of comparison. The contacts (60-11, 60-12, 60-13) in the first embodiment are referred to sandwiched contacts and can be said to be “in-line” (thus, 60-10 and 60-14 are not employed in this embodiment). In this embodiment, the hot side of the circuit interrupter 60-1 includes a line hot contact arm 40-10 and a load hot contact arm 40-20. The line hot contact arm 40-10 includes a dual-sided contact 60-11 which mates with the load hot contact 60-12, respectively, (disposed on the load hot arm 40-20) and the fixed hot load contact 60-13 when circuit interrupter 60 is in the reset state. Contacts 60-11, 60-12, and 60-13 share a common axis. The contacts are separated from one another when circuit interrupter 60 is in the tripped state. Again, contacts 60-10 and 60-14 are omitted in the first alternate embodiment.

In the alternate contact embodiment contacts 60-10 and 60-14 are included and contact 60-12 is omitted. Line contact 60-10 is connected to line hot contact arm 40-10 and load hot contact 60-14 is connected to load hot arm 40-20. Contact 60-11 is still connected to the line hot contact arm 40-10 but since hot line contact 60-12 is omitted it need only be a single sided contact having only to mate with contact 60-13. When circuit interrupter 60 is in the reset state contacts (60-10, 60-14) mate and contacts (60-11, 60-13) mate. Since contact pairs (60-10, 60-14) and (60-11, 60-13) lie on two axes this arrangement is referred to as a “staggered contact” arrangement. In the tripped state contacts (60-10, 60-14) and (60-11, 60-13) are separated.

The neutral side of circuit interrupter 60-2 includes a similar arrangement. The circuit interrupter 60 is configured to work in conjunction with the latch block assembly 50, the reset pin assembly 17, and the fault detection apparatus disposed on PCB 40 to drive the circuit interrupter 60 into the tripped state or the reset state. The fault detection apparatus disposed on PCB 40 is described below in the discussion of the schematic diagrams provided herein. (See, e.g., FIGS. 22-24).

The latch block assembly 50 is shown to include an upper latch block portion 52 and a lower latch block portion 54. The latch block 50 is coupled to the reset button by way of reset pin 17-5. A break spring 17-4 is disposed around the reset pin and exerts a break force during the tripping action. A make spring 50-1 is disposed between the separator 30 and the latch block assembly 50. The make spring 50-1 exerts a force against the latch block in the reset state to ensure that the contacts of the circuit interrupter 60 are closed and do not arc.

The lower latch block 54 is also coupled to an auxiliary switch KR1 disposed at the underside of PCB 40. The plunger 54-1 extends from the lower latch block through an opening formed in PCB 40 to open the auxiliary switch KR1. Accordingly, the auxiliary switch KR1 operates in conjunction with the circuit interrupter such that when the circuit interrupter is opened (i.e., device 10 is tripped), the auxiliary switch KR1 is opened, and vice-versa. The switch KR1 includes switch contacts KR1-1 disposed on either end of a conductive bus bar KR1-4 that make and break contact with switch contacts KR1-2 that are mounted on the underside of the PCB 40. The switch contacts KR1-2 are, in turn, electrically connected to circuit traces formed in PCB 40 in accordance with the present invention (See, e.g., the schematic of FIG. 22). Switch KR1 is closed when the circuit interrupter is in reset state due to spring KR1-3 being compressed between the back body 14 and bus bar KR1-4. In the tripped state, plunger 54-1 drives the bus bar to the open position causing spring KR1-3 to compress further. The length of plunger 54-1 is chosen to ensure contacts KR1-1 close before the contacts in circuit interrupter 60 close.

Referring to FIG. 7, a second perspective view 10-2 of the protective wiring device 10 depicted in FIG. 3 is disclosed. FIG. 7 is rotated relative to the view of FIG. 6 such that the separator cap 20, shown disposed above the separator member 30, is more clearly visible. Note that like reference numerals refer to identical or functionally-similar elements. FIG. 7 illustrates that the receptacle contact structures 30-1 (hot) and 30-2 (neutral) are disposed within the separator member 30 and isolated from the ground conductor 24 by the separator cap 20. The receptacle contact structures (30-1, 30-2) drop into pockets formed in the separator 30 and then held in place by the separator cap 20.

Referring to FIG. 8, a perspective view 10-3 of the protective wiring device 10 depicted in FIG. 3 is disclosed with the housing assembly and the separator cap removed. Again, like reference numerals refer to identical or functionally-similar elements. This view more clearly shows the configuration of the hot receptacle conductor 30-1 and the neutral receptacle conductor 30-2. The hot receptacle conductor 30-1 is substantially “L-shaped.” The first leg of the hot receptacle contact structure 30-1 extends along one side of the device in a longitudinal direction (within the separator 30) between the movistor MOV1 and the reset button 17. The second leg extends from the intersection with the first leg across the device to the opposite side of the device. The line hot contact 60-11 of the hot side of the circuit interrupter 60-1 is formed where the latitudinal leg of the hot contact structure 30-1 meets the longitudinal leg of the contact structure 30-1. One set of user-accessible hot receptacle contacts 30-12 is formed at the free end of the longitudinal leg and the other set of user-accessible hot receptacle contacts 30-12 is formed at the free end of the latitudinal leg. As such, the sets of hot receptacle contacts 30-12 are disposed “kitty-corner” at opposing corners of the device (See, e.g., FIG. 1). The neutral receptacle conductor 30-2 is substantially straight and extends approximately along the center longitudinal axis of the device 10 within the separator 30. The neutral set of contacts 30-22 is provided at each end of the neutral receptacle conductor 30-2.

Referring to FIGS. 8 and 9, the separator 30 also accommodates a test printed circuit board (PCB) 15-1 that includes contact pads that are connected to a first test wire lead 15-2 and a second test wired lead 15-3 (not shown). The first test wire lead 15-2 is connected to the hot receptacle conductor 30-1 and the second lead 15-3 is connected to the PCB 40. (See, e.g., FIG. 22). When the test button 15 is depressed by the user, a conductive bus bar underneath the button bridges the contact pads formed on test PCB 15-1, closing the test switch. When test button 15 is not depressed, a spring bias (not shown) between the button and PCB 15-1 keeps the test switch open.

Referring to FIG. 9, a perspective view 10-4 of the protective wiring device depicted in FIG. 3 is disclosed in accordance with an alternate embodiment of the invention. In this view, the housing assembly, separator and separator cap are removed. Once again, like reference numerals refer to identical or functionally-similar elements. While many of the components shown in this Figure have been described previously, the hot and neutral circuit interrupters (60-1, 60-2) are shown as sandwiched contacts, one of the contact arrangements that have been described already. Both this embodiment and the previous embodiment, however, are similar in layout. The line hot conductor 40-10 extends diagonally from the toroidal sensors L1/L2 (under the test button 15) to the hot circuit interrupter 60-1 (substantially under the reset button 17). The load hot terminal 14-20 is connected to the load hot conductor 40-20 which extends along the longitudinal edge of PCB 40 before it is bent 180° backwards (in a u-shape) towards the circuit interrupter 60-1. Thus, the line hot conductor 40-10 and the load hot conductor 40-20 form an acute angle with the vertex being located at the circuit interrupter 60-1. The line neutral conductor 40-12 also extends diagonally from the toroidal sensors L1/L2 (under the test button 15) to the neutral circuit interrupter 60-2 (substantially under the reset button 17). The load neutral terminal 14-22 is connected to the load neutral conductor 40-22 which extends latitudinally from the opposite edge of PCB 40 towards the neutral circuit interrupter 60-2. The line neutral conductor 40-12 and the load neutral conductor 40-22 also form an acute angle, with the vertex being located at the neutral circuit interrupter 60-2. This structure, along with that of the receptacle conductors (30-1, 30-2) allows the device 10 to conform to various form factors including those described herein.

As embodied herein and described in FIG. 10, a perspective view of a protective wiring system 100 in accordance with another embodiment of the present invention is disclosed. This embodiment is like the first embodiment in that the reset button and the test button are again diagonally disposed with respect to each other such that the test and reset buttons are disposed in opposite corners of substantially square area. This modular embodiment differs from the one depicted in FIGS. 1-9, in that the size of the front cover portion is increased from two modules to three modules. The aesthetic cover plate (not shown) employed with this embodiment will also require a three module sized opening, whereas the aesthetic plate opening in the previous embodiment is only two modules in size. The consumer may select the three module device 10 for any number of reasons including aesthetic ones.

Referring to FIG. 11, a perspective view of a protective wiring device depicted in FIG. 10 is disclosed. Once again, like reference numerals refer to identical or functionally-similar elements described previously. As before, the front cover 12 includes receptacle openings 16, test button 15 and reset button 17 and is framed by an aesthetic overlay that has a three module opening (not shown). This protective device 10 differs from previous embodiments in that it includes a three module front cover 12 and a three module back body 14. The aesthetic overlay and frame member 90 are described in U.S. patent application Ser. No. 13/680,675, which is incorporated herein by reference as though fully set forth in its entirety.

Another difference between this embodiment and the embodiment of FIGS. 1-9 is that the orientation of the receptacle openings 16′ in this embodiment are rotated 180° relative to the orientation of the receptacle openings 16 in the previous embodiment (FIGS. 1-9). Stated differently, the ground prong openings are disposed along the latitudinal edges of device 10, the neutral openings are disposed along the longitudinal edges and the hot blade openings are disposed in a central region of the front cover 12.

Referring to FIG. 12, a perspective view 10-1 of the protective wiring device depicted in FIG. 10 is disclosed with the front cover assembly removed. The device 10 includes a separator cap 20 that is disposed under the front cover 12 and over the separator 30. The separator cap 20 is fabricated from a non-conductive material and is configured to accommodate the shutter assemblies 22 and the ground strap conductor 24. The separator cap 20 of this embodiment is larger than the one employed in the previous embodiment and includes a flange portion 20-1 that accommodates the ground contact 24-1 at one end and the self-grounding connector 14-3 at the opposite end. The ground strap conductor 24 includes receptacle ground contacts 24-1 that are aligned with the ground prong openings 16-3 formed in the front cover 12. As described previously, the self-grounding connector 14-3 is configured to contact frame 90 to thereby provide a path to ground.

As before, the test button 15 and the reset button 17 are connected to components that are disposed under the separator cap 20. Reference is made to U.S. patent application Ser. No. 13/487,547, filed Jun. 4, 2012 which is incorporated herein by reference as though fully set forth in its entirety, for a more detailed explanation of the shutter assemblies 22.

Referring to FIG. 13, a perspective view 10-2 of the protective wiring device depicted in FIG. 10 is disclosed with the housing assembly and the separator cap removed. This view is similar to FIG. 8 in that it shows the hot receptacle conductor 30-1 and the neutral receptacle conductor 30-2 disposed within the separator 30. However, because the receptacle openings 16 have been rotated 180° relative to that of the previous embodiment, the relative positions and shapes of the hot receptacle conductor 30-1 and the neutral conductor 30-2 are also changed vis á vis the previous embodiment. (Compare FIGS. 10-11 to FIGS. 1-3). Accordingly, the hot receptacle conductor 30-1 extends substantially along the center longitudinal axis of the device 10 (within the separator 30) such that the hot receptacle contacts 30-12 are formed at each end thereof. The hot fixed contact 60-11 is connected to a branch portion 30-11 that extends from a central portion of the hot conductor 30-1 toward the side of the device 10.

The neutral receptacle conductor 30-2, on the other hand, has a rather complex shape and includes a central leg 30-21 that extends latitudinally from side-to-side within the separator 30. One set of neutral receptacle contacts 30-22 extends longitudinally from one end of the central leg 30-21 towards the movistor MOV1. Another set of neutral receptacle contacts 30-22 extends longitudinally from the other end of the central leg 30-21 away from the test button. A second neutral leg 30-23 is shaped like the number seven (“7”). It includes a base portion that extends from the central leg 30-21 and is disposed between the neutral receptacle contact set 30-22 and the hot receptacle contact set 30-12. Thereafter, the second leg 30-23 includes two ninety degree turns such that it positions the neutral fixed contact 60-12 between the reset button and the hot receptacle contact set 30-12.

Like previous embodiments, the separator 30 accommodates the test PCB 15-1 therewithin. The test wire 15-2 is connected to the hot receptacle conductor 30-1 and test wire 15-3 to the PCB 40.

Referring to FIG. 14, a perspective view 10-3 of the protective wiring device 10 depicted in FIG. 10 is disclosed. In this view, the housing assembly (12, 14), separator (30) and separator cap (20) are removed such that PCB 40 is shown in conjunction with the receptacle conductors 30-1 and 30-2. The line hot conductor is shown to extend from the toroidal sensors L1/L2 to form an acute angle relative to the load hot conductor 40-20. The hot receptacle branch conductor 30-11 is clearly shown to extend from the hot receptacle conductor 30-1 such that the fixed hot contact 60-13 is disposed overtop line hot contact 60-11 and load hot contact 60-12. Except for the receptacle conductors (30-1, 30-2), the components shown in FIG. 14 are the same as for the two module embodiment shown in FIG. 8.

FIG. 15 is another perspective view 10-4 of the protective wiring device 10 depicted in FIG. 10. This view is rotated about ninety degrees relative to the view provided by FIG. 14. Once again, like reference numerals refer to identical or functionally-similar elements described in the previous drawings. The housing assembly (12, 14), separator (30) and separator cap (20) are removed in this drawing. This view provides a clearer depiction of the neutral circuit interrupter 60-2 and the second neutral leg 30-23 of the neutral receptacle conductor 30-2. In particular, the second neutral leg 30-23 is parallel to, and is disposed overtop, the neutral load conductor 40-22 such that the fixed neutral contact 60-23, the line neutral contact 60-21 and the load neutral contact 60-22 are in vertical alignment. In addition, the line conductors 40-10 and 40-12 are clearly shown to extend diagonally across the PCB 40 to form an acute angle relative to their respective load conductors 40-20, 40-22. Spring 15-4 biases test button 15 in the open position when not being depressed by the user.

Referring to FIG. 16, a rear perspective view of the protective wiring device depicted in FIG. 10 is disclosed. The line terminals 14-1 and the load terminals 14-2 provide wire insertion openings (14-100, 14-120, 14-200, and 14-220) formed in the rear portion of the back body 14. Once the wires are inserted therein, the installer uses the screw terminals formed in the ends of the back body to screw down a plate to prevent the wires from being pulled out of the wire insertion openings.

Referring to FIG. 17, a perspective view 10-5 of the printed circuit board assembly of the protective wiring device depicted in FIG. 10 is disclosed. Like reference numerals refer to identical or functionally-similar elements described previously. The line hot conductor 40-10 extends diagonally from the toroidal sensors L1/L2 (under the test button 15) to the hot circuit interrupter 60-1 (substantially under the reset button 17). The load hot terminal 14-20 is connected to the load hot conductor 40-20 which extends along the longitudinal edge of PCB 40 before it is bent 180° backwards towards the hot circuit interrupter 60-1. As before, the line hot conductor 40-10 and the load hot conductor 40-20 form an acute angle with the vertex being located at the circuit interrupter 60-1. The line neutral conductor 40-12 also extends diagonally from the toroidal sensors L1/L2 (under the test button 15) to the neutral circuit interrupter 60-2 (substantially under the reset button 17). The load neutral terminal 14-22 is connected to the load neutral conductor 40-22 which extends latitudinally from the opposite edge of PCB 40 towards the neutral circuit interrupter 60-2. The line neutral conductor 40-12 and the load neutral conductor 40-22 form an acute angle with the vertex being located at the neutral circuit interrupter 60-2. This structure, along with that of the receptacle conductors (30-1, 30-2) allows the electro-mechanical design to conform to various form factors including those described herein.

The latch block 50 includes an upper latch block 52 and a lower latch block 54 which are described in greater detail below. The latch block 50 includes an upper latch block portion 52 and a lower latch block portion 54. A central aperture 52-1 in the upper latch block portion accommodates the reset pin 17-5. The upper latch block 52 further includes breaker arms 52-2 which are configured to force the line conductors 40-10, 40-12 downwardly during a tripping action to break the contact between the fixed contacts 60-13, 60-23 (not shown in this view) and the line contacts (60-11, 60-21). In particular, upper breaker arms 52-2 apply force to extension fingers 40-100 on line conductors (40-10, 40-12.) Similarly, lower breaker arms 52-20 (not shown in this view) apply force to extension fingers disposed on load conductors (40-20,40-22) during a tripping action to break the contact between the line contacts (60-11,60-21) and the load contacts (60-12,60-22.) In particular, lower breaker arms 52-20 apply force to extension fingers on load conductors (40-20, 40-22.) The breaker arms 52-2 assure a position of line conductors arms (40-10,40-12) and breaker arms 52-20 assure a position of load conductors (40-10,40-12) in the tripped state. As such, the upper and lower breaker arms assure a predetermined minimum separation distance between line contacts (60-11,60-21) and load contacts (60-12,60-22) when circuit interrupter 60 is in the tripped state. Note that the extension fingers on the load conductors are not visible in this view, but are similar to the extension fingers 40-100 provided on the line conductors.

The lateral portions of the solenoid bobbin assembly 70 are disposed between the line conductor arms (40-10, 40-12) while its end portions are positioned between the toroidal assembly L1/L2 and the latch block assembly 50. The overall length of the toroidal assembly L1/L2, bobbin assembly 70 and latch block assembly 50 can be greater than the distance between the line terminals (14-10,14-12) and the load terminals (14-20,14-22) since they are mounted to PCB 40 along a diagonal axis. The movistor MOV1 (shown in FIG. 15) is not depicted in this view for sake of clarity, but is connected between the line terminals 14-10 and 14-12.

As embodied herein and depicted in FIG. 18, a perspective view of the lower latch block assembly 54 shown in FIG. 17 is disclosed. The lower latch block 54 includes a central body 54-6 having a central aperture 54-3 formed therein. The central aperture 54-3 accommodates the reset pin 17-5 which extends through an opening in the latch member 56 in the reset state. The central body portion 54-6 also includes a side opening 54-5 that is configured to accommodate the lower portion of the U-shaped latch member 56 (not shown). The side opening 54-5 includes rails 54-50 that allow the lower portion of the latch 56, which is inserted into opening 54-5, to slide back and forth between the tripped state and the reset state. The latch 56 also includes arms 56-2 that extend around the central opening 54-3. The arms 56-2 include a catch that engages a stepped retainer portion of the central body 54-6. The catch and stepped portion resist the force applied by spring 58 to hold the latch in place. The latch spring 58 tends to force the latch member away from the central body 54-6 when no other stimulus is applied. When reset button 17 is depressed and released, the lower portion of latch 56 is lifted toward the central body 54-6 by reset pin 17-5 due to the bias of make spring 50-1. The upward motion of latch 56 in turn lifts lower latch block assembly 54 to the reset position by way of lifter arms 54-2. In particular, the lifter arms 54-2 lift the load arms (40-20, 40-22) which in turn lift the respective line arms (40-10, 40-12) upwardly such that the circuit interrupters 60-1 and 60-2 are reset. Conversely, when the device is tripped, the solenoid armature 70-1 (not shown) engages the front plate 56-1 of the latch 56 to compress the latch spring 58. This action releases the reset pin 17-5 from the latch and causes the lower latch block 54 to drop such that the circuit interrupters 60-1 and 60-2 are opened (tripped).

As described previously, the central body 54-6 also includes a plunger 54-1 that extends into an opening formed in the PCB 40. When the circuit interrupter 60 is in the tripped state, the plunger 54-1 engages the auxiliary switch KR1 such that it is open. When the circuit interrupter 60 is in the reset state, the plunger 54-1 is retracted such that the auxiliary switch KR1 is closed. See, e.g., FIGS. 6 and 22.

Referring to FIG. 19, a perspective view of the latch block assembly 50′ in accordance with another embodiment of the present invention is disclosed. Again, like reference numerals refer to identical or functionally-similar elements described previously. In this embodiment, central apertures are substantially eliminated from both the lower latch block 54′ and the upper latch block 52′. The upper latch block 52′ and the lower latch block 54′ include central rectangular shaped voids 52-1 and 54-3, respectively. The lower latch block 54′, however, does include an opening 54-6 in the bottom portion that aligns with the opening formed in the latch plate 56′.

As previously described herein, each side of the upper latch block 52′ includes an upper arm 52-2 and a lower arm 52-20. As more clearly shown in this figure, the line conductors (40-10, 40-12) and load conductors (40-20,40-22) are not cantilevered per se; rather they are driven between the reset and tripped positions respectively by arms (52-2,52-20) and arms 54-2. The positions of the line and load contacts (60-10, 60-11, 60-12, 60-22, 60-21, 60-23) thus rely on arms (52-2, 52-20, 54-2) for positioning.

FIG. 20 is a perspective view of the lower latch block portion 54′ of the latch block assembly 50′ depicted in FIG. 19. Again, like reference numerals refer to identical or functionally-similar elements described previously. This embodiment employs an L-shaped latch 56′ rather than the U-shaped latch used in the previous embodiment.

As embodied herein and depicted in FIG. 21, a perspective view of a protective wiring device 10 in accordance with yet another alternate embodiment of the present invention is disclosed. In this embodiment, the device is configured as a conventional wiring device that includes mounting ears 14-4′ instead of snaps that engage frame 90 (See, e.g., FIG. 1). Moreover, the line terminals 14-1 and the load terminals 14-2 are disposed along the sides of the back body 14 rather than in the manner previously described. However, this embodiment is like the first embodiment in that the reset button and the test button are again diagonally disposed with respect to each other such that the test and reset buttons are disposed in opposite corners of substantially square area. Thus, this embodiment may employ any of the electromechanical designs described herein. The electromechanical arrangement described previously allows the device to be configured in a variety of form factors including those shown herein. Stated differently, the present invention provides an efficient and cost effective way to employ a given design within a variety of form factors.

As embodied herein and depicted in FIG. 22, a schematic view of the protective circuit employed in the electrical wiring device of the present invention is disclosed. Moving from left to right in the schematic, it is seen that protective circuit 40 includes hot line terminals 40-10 and a neutral line terminal 40-12. On the load side of device 10, there is a pair of user accessible receptacles, each including a hot receptacle terminal 30-12 and a neutral receptacle terminal 30-22. The load terminals include load hot terminal 14-20 and load neutral terminal 14-22.

The ground fault circuitry 400 includes a differential transformer L1 which is configured to sense load-side ground faults. Transformer L2 is configured as a grounded neutral transmitter and is employed to sense grounded-neutral fault conditions. Both transformers are disposed in toroid assembly L1/L2 described previously. Both differential transformer L1 and grounded-neutral transformer L2 are coupled to the fault detector integrated circuit 406. Detector 406 is powered by a power supply circuit 408 connected to pin V⁺ on detector 406. The detector 406 output, provided on output pin SCR, is connected to the control input of SCR 410. Low pass filter 412, comprising resistor R10 and capacitor C7, filter the detector output signal. GFCI 400 also includes a snubber circuit 414 that includes resistor R4 and capacitor C8. Snubber circuit 414 prevents voltage transients from triggering SCR 410.

When SCR 410 is turned ON, solenoid 70 is energized, actuating circuit interrupter 60. Solenoid 70 remains energized for a time period that is typically less than about 25 milliseconds. Circuit interrupter 60 trips, resulting in the line terminals 14-1 being disconnected from respective load terminals 14-2. After the fault condition has been eliminated, the circuit interrupter 60 may be reset by way of reset button 17. In one embodiment, the reset mechanism 17 is purely mechanical in nature and does not include any electrical contacts for test initiation.

GFCI 400 addresses certain end of life conditions by denying power to the load when the device is unable to function. As an example of an end-of-life condition, solenoid 70 is susceptible to burn-out if SCR 410 becomes shorted out, or is permanently turned ON. Solenoid 70 may burn out if it is energized for more than about 1 second. Once the solenoid 70 burns out, the circuit interrupter 60 is incapable of being tripped. Solenoid burn-out prevention is provided by auxiliary switch 422 (KR1). Auxiliary switch 422 is configured to open when the circuit interrupter 60 is in the tripped position. If SCR 410 is shorted out or permanently ON, auxiliary switch 422 ensures that solenoid 70 is not permanently connected to a current source. The user may attempt to reset the device 10 by depressing the reset button 17, but the circuit interrupter 60 will immediately trip in response to the current flowing through the solenoid 70. Because the latch block 50 is coupled to the auxiliary switch 422 by plunger 54-1, auxiliary switch 422 is opened before solenoid 70 can be burned out.

In another embodiment, another failure mode is addressed by GFCI 400; this mode relates to the end-of-life failure mode of movistor MOV1. MOV 1 is disposed in series with auxiliary switch 422 and trip solenoid 70. This arrangement significantly reduces the probability of damage due to an over-current situation. When MOV 1 reaches end-of-life and shorts out, trip solenoid 70 is energized and auxiliary switch 422 is opened. As previously described, when auxiliary switch 422 opens, the flow of short circuit current is terminated before any damage to device 10 ensues.

GFCI 400 also includes trip indication circuit 426. Trip indicator 426 is implemented by placing LED1 and series resistors (R11-R14) in parallel with auxiliary switch 422. LED1 is configured to emit a visual signal when circuit interrupter 60 and auxiliary switch 422 are in an open state (tripped). In an alternate embodiment LED 1 is replaced by an annunciator that provides an audible signal when interrupter 60 is in the tripped state.

GFCI 400 also includes a test circuit 150. The test circuit 150 is coupled between the line neutral terminal 14-12 and the hot receptacle terminal 30-12. The test circuit 150 includes a test button assembly 15 shown here to include a switch disposed in series with test resistor R1.

As embodied herein and depicted in FIG. 23, a schematic view of a ground fault circuit interrupter 400 in accordance with another embodiment of the present invention is disclosed. Again, like reference numerals refer to identical or functionally-similar elements. The instant embodiment includes universal auto-test and indicator functionality that is not present in the previous embodiment.

As before, the ground fault circuitry 400 includes a differential transformer L1 which is configured to sense load-side ground faults, i.e. ground faults located in loads connected to load terminals 14-2 or receptacle contacts (30-12, 30-22) and transformer L2, which is configured as a grounded neutral transmitter that is configured to sense grounded-neutral fault conditions. Both transformers are disposed in toroid assembly L1/L2 as described above. Both differential transformer L1 and grounded-neutral transformer L2 are coupled to the fault detector integrated circuit 406. Detector 406 receives power from a dual power supply circuit 408 that is described in greater detail below. The output of the detector 406 is connected to the control input of SCR 410. When SCR 410 is turned ON, the dual-solenoid 70′ is energized to actuate the circuit interrupter 60 such that the circuit interrupter 60 and the auxiliary switch 422 are tripped (opened). Solenoid 70′ remains energized for a time period that is typically less than about 25 milliseconds. When the circuit interrupter 60 trips, the line terminals 14-1 are disconnected from their respective load terminals 14-2 or receptacle contacts (30-12, 30-22.) After the fault condition has been eliminated, the circuit interrupter 60 may be reset by way of reset button 17 which has been depicted and described previously.

As its name suggests, the grounded neutral transmitter L2 is configured to detect a grounded neutral condition. As an initial point, note that the line neutral conductor (i.e., the conductor that is connected to neutral line terminal 14-12) is typically grounded in the electrical circuit at the panel—this does not constitute a grounded neutral fault condition. When a grounded neutral condition is not present, the grounded neutral transmitter L2 is configured to couple equal signals into the hot and neutral conductors. Because the differential transformer L1 is configured to sense a current differential, the equal signals provided by grounded neutral transmitter L2 effectively cancel each other out. On the other hand, a grounded neutral condition does occur when the load neutral conductor (i.e., the conductor that is connected to load neutral terminal 14-22 or neutral receptacle contact 30-22) is accidentally grounded. This creates a parallel conductive path (relative to the neutral return path) between the neutral line terminal 14-12 and neutral load terminal 14-22. As a result, another signal circulates around this current loop and it is coupled onto the neutral conductor (but not the hot conductor) to create a differential current. The differential transformer L1 senses the differential current between the hot and neutral conductors and the detector 406 generates a fault detection signal in response thereto. The fault detection signal trips the circuit interrupter 60.

In reference to the dual power supply circuit 408, it is provided to accommodate the needs of both the detection function (described above) and the universal auto-test circuit 401 described below. Dual supply 408 includes power supply portion 408-1 which includes diode D1 in series with resistors R6 and R7. The series circuit is disposed between the cathode of diode D4 and the anode of diode D6. The power supply portion 408-1 is thus connected to line hot via diode D4 and solenoid 70′ and is further configured to provide power to the supply terminal of detector 406 via diode D6. Diode D4 is further connected to power supply portion 408-2 which includes diode D2 in series with resistors R8 and R10; the series circuit is connected to the cathode of diode D6. Power supply portion 408-2 is configured to charge capacitor C6 whereas power supply portion 408-1 is configured to charge the parallel capacitor bank 408-3 (C16-C20). The total capacitance in bank 408-3 is greater than that of capacitor C6. The capacitor bank 408-3 has enough stored energy to maintain the power supply voltage during the negative half cycle auto-test. When the AC line cycle is negative, the diode D6 is forward biased, thereby coupling capacitor bank 408-3 to capacitor C6. Because the power supply is active during the negative half cycle, detector 406 is responsive during the auto-test.

When the GFCI 400 detects a fault condition, it is configured to interrupt the circuit interrupter 60 during the positive half-cycle of the AC line cycle. In order to meet the trip time requirements, power supply portion 408-2 is configured to charge to the full supply voltage in less than about 2 milliseconds. This means that during the positive half cycles, a hazardous ground fault condition is detected and interrupted quickly. On the other hand, power supply portion 408-1 takes longer to come up to full charge due to the large value of capacitor bank 408-3. Power supply portion 408-1 charges with a time constant that is approximately 15 milliseconds. However, due to reverse biasing of diode D6, power supply portion 408-2 is not prevented from charging quickly. In summary, detector 406 relies on power supply 408-2 during the positive half cycles for ground fault detection and relies on power supply 408-1 for auto-testing during the negative half cycles.

At this point, it is helpful to bring the universal auto-test circuit 401 into the discussion since one of the purposes of the dual power supply 408 is to support the auto-test circuit 401. The auto-test circuit 401 generates a simulated grounded neutral test signal by way of wire loop 402 when FET (Q2) is turned ON. When FET 404 (Q2) is turned ON, the grounded neutral transmitter L2 produces an oscillating signal that is a function of the full power supply voltage. The ON state resistance of FET 404 is less than about 4 Ohms. Thus, the wire loop 402, in combination with the FET 404 (in the ON state), forms a loop that passes through the differential transformer L1 and neutral transmitter L2 to simulate a grounded neutral condition. In an alternate embodiment, instead of having a third wire passing through the transformers (L1, L2) the wire loop 402 may incorporate a portion of the neutral conductor that is disposed between line neutral terminal 14-12 and load neutral terminal 14-22. One advantage for placing the third wire within the wire loop relates to improved noise immunity. When the third wire is employed, the wire loop 402 and the neutral conductor are isolated such that the current propagating in wire loop 402 during the self-test is not affected by voltage drops or electrical noise propagating in the neutral conductor. Noise propagating on the neutral conductor could otherwise impair the test fault signal and its detection by the GFCI.

The timing of the FET ON state is controlled by the timing resistor R14. In one embodiment of the present invention, the FET 404 is turned ON near the conclusion of the positive half cycle of the AC power source and remains ON through a portion of the negative half cycle to produce the test fault signal. The grounded neutral transformer L2 generates a differential current in response to the test current propagating in wire loop 402. The differential current is, in turn, sensed by transformer L1. If the circuit is working properly, the sensor signal provided by L1 should be deemed by detector 406 as a fault. As described above, during normal operations and when the GFCI 400 is operating properly, the fault detector 406 provides a fault detection signal that is sufficient to turn SCR 410 ON. However, the auto-test is performed during the negative half cycle or late in the positive half cycle such that SCR 410 will not be turned ON during the positive half cycle at a time that could cause nuisance tripping of the circuit interrupter. In one embodiment, SCR 410 is turned ON late in the positive half-cycle of the AC line cycle where the amount of current flowing through the SCR 410 is not sufficient to energize the dual-solenoid 70′. In another embodiment, SCR 410 is turned ON during the negative half cycle, remaining ON until power supply 408 is sufficiently discharged before the next positive half cycle, that occurring before the start of the next positive half cycle. Moreover, SCR 410 is prevented from conducting current through dual-solenoid 70′ during the negative half cycle by diode D4.

One reason for using a relatively lengthy time duration for the simulated fault signal generated by loop 402 is to ensure that detector 406 has sufficient time to detect the self-test. One drawback to this approach relates to the duration of the magnetic flux in the sensor core. Specifically, if the magnetic flux in the core carries over into the subsequent positive half cycle, the resultant sensor output would cause detector 406 to improperly turn SCR 410 ON and nuisance trip the device 10. For this reason, the output voltage of the dual power supply 408 is collapsed before the conclusion of the negative half cycle. One reason why the collapsible power supply voltage prevents nuisance tripping relates to the inability of grounded neutral oscillations to persist in the absence of the power supply output voltage. Even when FET 404 is turned ON, there is substantially no magnetic flux in the sensor core once the power supply voltage collapses. Thus, if the power supply voltage is collapsed before the conclusion of the negative half cycle, the grounded neutral oscillations that otherwise would be generated by FET 404, cannot carry over into the positive half cycle. Thus, the dual power supply 408 prevents nuisance tripping.

The nuisance tripping prevention feature is now described in greater detail. During the self-test, FET 404 is turned ON and the grounded neutral transmitter 102 (L2) produces an oscillating signal that is a function of the full power supply voltage. If the detector 406 is operational, SCR 410 is turned ON at about 225°-280° of the AC line cycle (i.e., during a portion of the negative half cycle). As a result, capacitor C6 and capacitor bank 408-3 (by way of resistor R13, opto-coupler U2, and diode D5) are dump-discharged via SCR 410 to thereby collapse the output voltage of the power supply. The discharging process occurs gradually because of the time constant associated with capacitor bank 408-3. As the power supply voltage gradually collapses in accordance with the aforementioned time constant, the magnitude of the oscillating signal produced by the grounded neutral transmitter L2 also diminishes. In turn, the grounded neutral simulation current propagating around loop 402 is also reduced. Finally, the flux in the transformer core is so low that the sensor signal it provides to the fault detector 406 does not represent a fault condition. The above stated process transpires before the conclusion of the negative half cycle. Accordingly, little or no flux is present in the transformer core at the start of the subsequent positive half cycle. In one embodiment of the present invention, the capacitor bank 408-3 time constant is about 0.5 milliseconds and the period of the grounded neutral oscillation is about 0.15 milliseconds.

As noted above, SCR 410 turns on during the negative half cycle, however current through SCR 410 is prevented from conducting through dual-solenoid 70′ during the negative half cycle because diode D4 is reverse biased. Watchdog circuit 421 monitors whether SCR 410 is turned ON or not, and it functions as follows: When SCR 410 turns ON indicative that GFCI 400 is operational, power supply 408 discharges via resistor R13, the diode portion of opto-coupler U2, diode D5, and SCR 410. Because of the current through its diode portion, the transistor portion of opto-coupler U2 turns ON to discharge the watchdog capacitor C12. Stated differently, the negative half-cycle test is performed every AC line cycle such that the charge accumulated on C12 should be discharged every line cycle. However, when there is an end of life condition, SCR 410 or opto-coupler U2 will fail to turn ON. If there is failure to turn on within four or five line cycles, the voltage on C12 becomes greater that the breakover voltage of diac Q3 and Q3 will conduct to turn opto-coupler U3 ON. The transistor portion of U3 is connected to the control input of secondary SCR Q4, and therefore, when U3 conducts, SCR Q4 is turned on such that the secondary side of the dual-solenoid 70′ is energized to trip the circuit interrupter 60 and the auxiliary switch 422. In other words, if the self-test performed by universal auto-test circuit 401 fails for a predetermined period of time, the watchdog circuit 421 will trip the device 10.

A wiring state detection circuit 420 is configured to prevent miswiring upon initial installation. Detection circuit 420 includes resistors R9, R15, and fusible element S1. When power is initially applied to the load terminals 14-20, 14-22 and the protective device is reset, the interrupting contacts 60 are tripped within about 25 milliseconds because detection circuit 420 creates an imbalance in the differential current flowing through sensor L1. The imbalance is detected by detector 406, SCR Q1 is turned ON and the device is tripped in the manner described above. Once AC power is properly connected the line terminals 14-10, 14-12, the fusible element S1 is cleared after the device is again tripped. Subsequently, the interrupting contacts 60 may be closed by reset assembly 17. The dual-solenoid 70′ may be energized for about 100 milliseconds before it is damaged and burns out; thus, it is not designed to burn out during the interval that SCR Q1 is conductive (i.e., about 25 milliseconds).

Miswiring is also prevented on re-installation. Referring back to the watchdog circuit 421, the charging path includes resistors R21, R27 and diode D9 disposed between load hot and watchdog capacitor C12 coupled to load neutral. When the device is miswired, i.e., when the AC source voltage is connected to the load terminals, the capacitor C12 is charged up. As with an end of life condition, the voltage on C12 becomes greater than the breakover voltage of diac Q3. When the reset button 17 is manually operated attempting to reset the device, the watchdog circuit 421 will energize the dual-solenoid 70′ to thereby trip the circuit interrupter 60. Each time reset is attempted; this process keeps repeating itself, until device 10 is properly wired. When power is properly applied to the line terminals and circuit interrupter 60 is in the tripped state, capacitor C12 will not charge due to the circuit interrupting contacts being open, and so device 10 can be reset.

Miswire protection on re-installation is afforded by coupling the watch-dog capacitor C12 to the load side of circuit interrupter 60. The other circuitry including the GFCI detector is coupled to the line side of circuit interrupter 60. The two opto-isolators, (U2, U3) electrically isolate these line side and load side circuits when circuit interrupter 60 is in the tripped state. Summarizing, opto-isolator U2 couples a drive signal from the line side circuit to the load side circuit. Opto-isolator U3 couples a drive signal from the load side circuit back to the line side circuit.

In reference to the indicator circuit 418, once the device 10 trips, the current from line hot 14-10 is diverted from the auxiliary switch 422 and through LED D10, depicted as LED 17-2 in FIG. 15, such that LED D10 is illuminated. If the auxiliary switch 422 is opened because SCR 410 failed to turn ON during an auto-test or because of miswiring, the indicator driving circuit 416 will cause the indicator LED D10 to flash. Note that SCR 410 (Q1) is also coupled to the indicator driving circuit 416. Specifically, when SCR 410 is turned ON as a result of the auto-test cycle, it is also configured to discharge capacitor C15 in addition to the watchdog capacitor C12. If SCR 410 fails to turn ON for four or five line cycles, the voltage on C15 becomes greater than the breakover voltage of diac Q5 such that Q5 begins to conduct. When diac Q5 conducts, SCR Q6 is turned ON causing transistor Q7 to momentarily turn ON. When Q7 is ON, current is diverted away from LED D10 and it is turned OFF. Q7 is only ON momentarily because diac Q5 will turn OFF when the voltage on capacitor C15 drops about seven (7) volts. Once diac Q5 stops conducting, capacitor C15 will charge up again and the cycle will repeat. Briefly, stated, the indicator LED D10 will provide a flashing red light indicating the device 10 has reached an end of life condition. The flashing light will continue until the consumer removes the device 10 from the source of AC power.

Referring to FIG. 24, a schematic view of an arc fault circuit interrupter in accordance with an embodiment of the present invention is disclosed. The AFCI 90 may be implemented using any of the form factors described herein (i.e., FIG. 1, 3, 10, 11 or 21). The end of life detection feature and the miswire prevention features may be adapted to AFCI 90 (i.e. FIG. 22 or 23.) AFCI 90 protects an electrical circuit and includes at least a neutral conductor 900 and a line conductor 901 connected to a power source (not shown). A ground conductor (not shown) is optionally present. AFCI 90 detects electrical arcs occurring between line conductor 901 and ground, neutral conductor 900 and ground should the power source be of reverse polarity, or line conductor 901 and neutral conductor 900.

A circuit interrupter 902 is disposed between the line conductor 901 and the load 99. This embodiment incorporates a first stage arc sensor 920, shown as a current transformer, which is configured to respond to the rate of change of neutral and/or hot conductor current with respect to time. Sensor 920 may be designed with a physically small core of a type and number of secondary turns which gives optimum sensitivity during arcing. Either a single conductor (hot line) or both conductors can pass thru the sensor. The arc fault detector detects arcs that are either hot to ground or hot to neutral. The sensor 920 provides two detector/amplifiers 921, 922 with sensor data. The detectors 921, 922 may be implemented using any suitable device, such as an integrated circuit used to detect ground faults (e.g., RV4141A). The detector 921 is referred to as the di/dt stage, because it detects the change in current with respect to time. Detector 921 also has a high pass filter capacitor 911 on its input side. The detector 922 is referred to as the 60 Hz or “threshold” stage, and uses a low pass filter capacitor 912 in a feedback stage. The 60 Hz threshold detector 922 controls the level at which an arcing condition is to be detected, e.g., at a 75 Ampere or greater load current.

The outputs of both stages are combined by a logic AND gate 913, and this output is further combined by a second logic AND gate 914 with a timer output. Stated differently, the input current signal must exhibit a rate of change that exceeds a predetermined rate, and a magnitude in excess of a predetermined threshold, within the time frame selected by the dimmer delay timer 952. If these conditions are met, a positive pulse is applied to the base of Q3 such that SCR 954 is turned ON. This energizes the solenoid 960 to trip the circuit interrupter 902.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening.

The recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not impose a limitation on the scope of the invention unless otherwise claimed.

No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. There is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

	Number	Date	Country
Parent	14977740	Dec 2015	US
Child	15240748		US
Parent	13761846	Feb 2013	US
Child	14977740		US

	Number	Date	Country
Parent	13680675	Nov 2012	US
Child	13761846		US

PROTECTIVE ELECTRICAL DEVICE

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