MXPA96001902A - Discharge circuit switch to tie - Google Patents

Abstract

The present invention relates to an earth leakage circuit interrupter line cord plug (GPCI) using an electrically latched relay, in place of a circuit breaker or other type of mechanical fastening device, to interrupt the current load alternates when a ground loss condition occurs. In order to reduce the size of the relay and minimize the cost and complexity of the GPCI plug, the relay and movable contact structures are mounted directly to the circuit board carrying the remaining components of the GFCI circuit. In a preferred embodiment, the relay contact structures are integral with the plug blades of the GFCI plug. The relay-contact contact structures preferably comprise deflectable spring arms which are pre-loaded when the relay contacts are in the open position in order to control the contact space and which deviate beyond the contact closure point when the relay contacts are in contact with the relay contacts. the closed position in order to increase the closing force. The main electrical components of the GFCI plug, including the relay contacts, relay coil and sensing transformer, are mounted on the circuit board in a generally tandem or in line arrangement in order to minimize the dimensions of the plug

Description

CIRCUIT SWITCH FOR LOSS TO GROUND CIRCUIT Reference to Related Request: This application is a continuation in part of the previous application Serial No. 08 / 115,020, filed by Thomas M. McDonald on September 2, 1993 and entitled "Manually Adjusted Earth Loss Circuit Interrupter", whose disclosure is incorporated herein by reference.

Field of the Invention The present invention relates to a ground loss circuit interrupter device (6FCI) for protecting an AC load circuit. More specifically, the invention relates to a GFCI device that is modeled on a line cord plug and uses a relay, rather than a circuit breaker or other type of mechanical fastening device, to open and close the circuit. AC load. * BACKGROUND OF THE INVENTION Conventional GPCI devices are designed to fire in response to the detection of a ground loss condition in an alternating current load. Generally, the ground loss condition results when a person comes into contact with the line side of the AC load and one earth at the same time, a situation that may result in serious damage. The GPCI device detects this condition using a sensing transformer to detect an imbalance between the currents flowing in the line and neutral conductors of the alternating current supply, as will occur when part - of the current on the line side as being diverted to ground When such an imbalance is detected, a mechanically clamped circuit breaker circuit inside the GFCI device immediately trips to an open condition, thereby opening both the? two of the line of alternating current and eliminating all the energy 0 of the load. Many types of GFCI devices are capable of firing not only by contact between the line side of the alternating current load and ground, but also by a connection between the neutral side of the alternating current load and ground. The last type of connection can result from a defective load, or from improper wiring or installation, is potentially dangerous because it can prevent a conventional GFCI device from firing at the intended threshold level * of differential current when a line loss to ground occurs. 0 GFCI devices can be connected to junction boxes or circuit breaker panels to provide central protection to alternating current wiring through a commercial structure or residence. More commonly, however, GFCI devices are incorporated into electrical receptacles that are so designed for installation in various locations within a building. A typical receptacle configuration, as shown, for example, in U.S. Patent No. 4,568,997 to Bienwald et al., Includes test and reset pressure buttons and a lamp or light emitting diode (LED) that indicates that the circuit is operating normally. When COJJ returns a ground fault in the protected circuit, or when the test boost is depressed, the GFCI device trips and an internal circuit breaker opens both sides of the current line to? triple The trip of the circuit breaker causes the reset -0 button to jump out and the LED to extinguish, providing a visual indication that a ground fault has occurred. In order to readjust the GFCI device, the reset button is pressed in order to close and hold the circuit breaker and this also causes the LED to light up again. 5 Portable GFCI devices have been designed for use in situations where the cea power supply circuit. available does not include a central GFCI device or # type of receptacle. These portable devices can be incorporated into line plugs, extension cords, and plug-in units and are often used with power tools and other types of potentially hazardous energy equipment in construction sites and the like. of portable GFCI devices can be found in U.S. Patent No. 4,197,567 and Dietz et al. and U.S. Pat.

»Joined 5,229,739 to Legatti et al. However, like the GFCI receptacle-type devices described above, the portable GFCI devices typically rely on mechanical circuit breakers to trip in response to ground-loss condition. Mechanical circuit breakers add undesirable complexity and cost to the GFCI circuit and are also subject to failure due to the mechanical nature of the firing and clamping functions. The newer types of GFCI devices employ relays 0 instead of circuit breakers or other types of mechanical fastening devices, to interrupt the load energy when a ground fault condition corrects. An electronic circuit controls the current flow of the relay coil and, the relay contactors serve to open and close both sides of the alternating current line in response to the presence or absence of a fault or loss to ground signal. In these devices only a momentary, push button switch, simple # is needed to perform the reset function, since the clamping of the relay contacts is done electronically more - well than mechanically. This results in a simpler, less expensive and safer device. As described in the aforementioned co-pending patent application of Thomas M. McDonald Serial No. 08 / 115,020, a GFPC relay type device can be designed to incorporate a particularity of manual austere, in that of the reset pressure button must be pressed before power can be applied to an AC load. This - provides protection against unexpected start of the a.c. when the GFCI device is initially connected or after a power supply switch, which can be dangerous when power equipment is involved. Unfortunately, the substitution of a de-type circuit for a mechanical circuit breaker is difficult in the case of portable GFCI devices, particularly those that are incorporated into AC line cord plugs. These devices must be relatively small in order to to perform its intended function and, a conventional relay, which must be moistened on a circuit board together with the relatively large number of electrical components required for the clamping and firing functions, takes up a considerable amount of space. Ideally, it would be desirable to reduce the size of the relay-type GFCI device so that it can be incorporated into a c.a. of relatively small dimensions. of the present invention is proport a relay-type GFCI device that is relatively small and compact, allowing it to be incorporated into an AC line cord plug. A further object of the invention is to provide a A relay-type GFCI device in which a novel relay contact arrangement is used, both to reduce the size of the relay and to minimize the cost and complexity of the GFCI device. Still another object of the invention is to provide a relay-type GFCI device in which the main electrical components of the device, including relay coil relay contacts and percept transformation, are mounted on a circuit board in a generally tandem dipsolution or - * 0 online in order to reduce the dimensions of the device to the minimum. The above objects are substantially achieved by providing an in-ground loss circuit breaker plug comprising a housing having a pair of plug blades 5 for connection to an AC receptacle and a pair of output terminals for connection to an AC load, and electrical circuits inside the housing to provide - # ground loss protection to an AC load connected to the output terminals. The electrical circuit includes a relay 0 comprising a relay coil and a pair of contact-relay sets for selectively connecting and disconnecting the plug blades and the output terminals. The electrical circuit also includes an electronic circuit coupled to the relay coil to keep the relay contact assemblies in a closed position to connect the plug-in terminals to the terminals. output in the absence of a ground loss condition and, to cause the relay contact assemblies to move to an open position to disconnect the plug blades from the output terminals in response to a ground loss condition. In accordance with another aspect of the present invention, a relay contact arrangement for use in an earth leakage circuit breaker plug comprises a circuit board, an integral plug blade and contact structure. fixed relay carried by the circuit board. The movable relay contact structure carried by the circuit board and an actuator for moving the movable relay contact structure towards and out of contact with the fixed relay contact structure. In accordance with an additional aspect of The present invention, a method for opening and closing the line or neutral side of an alternating current load in a ground fault switch is provided. The method comprises the steps of providing a fixed relay contact structure and a movable relay contact structure that is movable to and out of contact with the fixed relay contact structure, with the movable contact structure being provided in the form of a cantilevered spring arm having a secured end, a free end and a contact portion positioned at an intermediate point between the secured end and the free end pS. * make contact with the fixed-line contact structure; connecting one of the fixed and movable relay contact structures to the line or neutral side of an alternating current source and the other of the fixed and movable relay contact structures to the same side of the alternating current load; opening the line or neutral side of the alternating current load by moving the spring arm to a first stop position in which the spring arm is not in contact with the fixed contact structure; and closing the line or neutral side of the alternating current load by applying a force to the free end of the spring arm to move the spring arm to a second stop position in which the spring arm is biased to carry the portion of the spring arm. contact it to contact with the fixed relay contact structure. The distance moved by the free end of the contact arm from the first stopping position to the second stopping position is greater than the distance necessary to bring the contact portion of the spring arm into contact with the fixed contact structure, so that the closing force applied between the contact portion of the spring arm and the relay contact structure is increased.

Brief Description of the Drawings Referring now to the drawings, which form a part of the original exposition: Figure 1 is an external perspective view of a - * earth leakage circuit interrupter plug constructed in accordance with a preferred embodiment of the present invention; Figure 2 is a partial cut-away view of the ground loss circuit interrupter plug of Figure 1; Figure 3 is an elevation view of the earth leakage circuit interrupter plug of Figure 1, with a rear cover removed to illustrate certain internal components; Figure 4 is an elevation view of the rear cover that has been separated from the earth leakage circuit interrupter plug in Figure 3, which illustrates internal details thereof; Figure 5 is an enlarged perspective view of the circuit board used in the earth leakage switch switch plug of Figure 1, illustrating the electrical components carried therein; # Figure 6A is an elevation view of the upper portion of the circuit board of Figure 5, illustrating the 0 relay contact assemblies in the closed position; Figure 6B is an elevation view similar to that of Figure 6A, illustrating the relay contact assemblies in the open position; Figures 7 and 8 are schematic diagrams of two different electric coils 5 that can be used in the socket of loss-to-ground circuit interrupter of Figures 1 -6; Figures 9A, 9B and 9C are front, side and bottom views of a modified construction that can be used for the spring arm of each relay contact assembly in the GFCI plug 10 of Figure 1; and Figure 10 is an elevation view of the upper portion of a modified printed circuit board that is designed to accommodate the spring arm shown in Figures 9A 9B and 9C.

Detailed Description of the Preferred Modes A ground loss circuit interrupter (GFCI) plug 10 constructed in accordance with a preferred embodiment of the present invention is illustrated in Figures 1 and 2. The GFCI plug 10 includes a plastic housing that is made of a rear cover 12, a front cover 14 and a cover 16 of the wiring chamber. The rear cover 12 extends vertically from one end of the GFCI plug 10 to the other, while the front cover 14 has a lower edge 18 terminating some distance above the bottom of the GFCI plug 20. The remaining distance between the lower edge 18 and the front cover 14 and the bottom of the plug 10 GFCI is occupied by the cover 16 of the wiring chamber. The front cover 14 is attached to the rear cover 12 along its periphery The entire section is formed by an adhesive along a seam line 20 to form a water-tight envelope. The wiring chamber cover 16 is attached to the rear cover 12 - by screws (not shown) so that the wiring chamber cover 16 can be separated for the purpose of ligating or - removing an AC line cord. In a preferred embodiment, the GFCI plug 10 is approximately 12.70 inches in height, about 5.08 inches in width and (except in the area of the plug blades) approximately 3.81 inches in depth. As best seen in Figure 2, a pair of plug blades -22 and 24 and a ground pin 26 project horizontally outwardly from the rear cover 12 of the GFCI plug 10 to allow it to be connected to a bulk receptacle. alternating current connected to earth, with three projections, conventional. The plug blade 22 corresponds to the line (hot) side of the c.a. and, the plug blade 24 # responds to the neutral side of the c.a. In some embodiments, the plug blades 22 and 24 may be of different sizes - to ensure proper polarization; however, this is not necessary when a ground pin 26 is used as in the ilsutrated embodiment. In order to preserve the watertight nature of the housing portion of GFCI at;; H;; between the covers 12 and 14, a generally rectangular flange 28 is formed around the plug blades 22, 24 and the 26 of ground to form a shallow cavity with the -wall of the rear cover 12. This cavity is filled with an encapulation compound 30 which seals the specimens through which the plug blades 22 and 24 and the ground pin 26 protrude through the wall of the rear cover 12. The potting compound 30 also provides additional stiffness to the plug blades 22 and 24 and prevents deflection of the plug blades 22 and 24 from being transmitted to the inner portions of the blades. This is a significant sale, since, as will be described in more detail below, the internal portions of the plug blades 24 and 26 form part of the relay contact structure of the GFCI circuit. Referring again to Figure 1, the front cover 14 of the GFCI plug 10 is formed with a recessed area 32 in which two momentary pressure pushbutton switches 34 and 36 are provided. The pushbutton switch 34 serves as a TEST switch that allows the GFCI encoder 10 to be tested if a loss condition is earthed. The second pressure button 36 serves as either an ADJUST or RESET switch., depending on whether the internal circuit of the GFCI plug 10 is designed to provide manual or automatic adjustment, as will be discussed in more detail below. Both press button switches 34 and 36 are of water-tight, rubber-membrane-like preference or * of the board type, as described in the co-pending patent application, commonly assigned, Serial No. 08 / 229,855, filed by ard E. Strang et al. on April 19, 1994 and entitled "Compression Seal Assembly". of Button Well ", said Sulfidity being incorporated herein by reference. In this type of switch, the pressing of the pressure button 34 or 36 causes an internally mounted conductive tab or layer to contact two conductive remnants on the back surface of a printed circuit board housed within the GFCI socket 10. . Placed adjacent to the pushbutton switches 34 and 36, at the edge of the recessed area 32, there is a lens 38 for a light emitting diode (LED) or a neon bulb - carried by the circuit board within the socket. 10 of GFCI. The LED or neon bulb, when illuminated, provides an indication that the relay contacts within the 10 GFCI plug are closed and that power is available in the AC receptacle - to which the plug 10 is connected. GFCI. As illustrated in Figure 1, the GFCI-plug 10 has a generally vertical, upright configuration, with the blades 22 and 24 detached and the ground pin 26 extending horizontally outward from the rear upper portion of the housing and with the pressure buttons 34 and 36 and lens 38 - accessible in front of the housing. A cord 40 of line-c.a. of field wire extends from the bottom of the plug - 10 of GFCI and serves to connect the plug 10 of GFCI to a ga from c.a. (not shown), which may consist of an energy tool, apparatus or the like. When the plug blades 22 and 24 and the ground pin 26 are inserted into a conventional three-pronged alternating current receptacle, the GFCI plug 10 serves as a line cord plug for the altering current load device. which is fixed by means of the line cord 40. It will be appreciated that the generally vertical, elongated configuration of the GFCI plug 10 is advantageous by minimizing its depth and increasing its stability when connected to a C.A. receptacle. mounted on the wall. Figure 3 is an elevation view of the GFCI plug 10 as seen from the right hand side in Figure 1, with the rear cover 12 removed and the line cord 40 not yet fixed. The front cover 14 defines a shallow, generally rectangular cavity in which a similarly configured circuit board is received. The circuit board 42 provides physical support for the plug blades 22 and 24, and also carries the various electrical components that are required to detect and respond to ground loss conditions. These include a relay contact assembly 44 for opening and closing the line side of the AC supply, a similar relay contact assembly 46 for opening and closing the neutral side of the AC supply, a winding coil and assembly. 48 for opening and closing the relay contact assemblies 44 and 46 by means of an actuator 50 and a pair of transformers 52 and 54 toroids that are used to detect ground loss conditions. A line conductor 56 connects the load side of the relay contact assembly 44 to a line terminal 58 and a neutral conductor 60 connects the load side of the relay contact assembly 46 to an output terminal 62. -neutral. The line and neutral conductors 56 and 60 pass both through the transformer cores 52 and 54 and are 1 to 2 at their lower ends to conductive remnants (placed on the reverse side of the printed circuit board 42 and are not vj ^ sible in Figure 3) that contact the output terminals 58 and 62. The lower ends 64 and 66 of the output terminals 58 and 62, respectively, are provided with an enlarged rectangular configuration to serve as nut plates. The holes 68 and 70 are formed in the nut plates-to accommodate the screws 69 (shown in Figure 5) which are used with corresponding nuts 71 (also visible in Figure 5) to secure the line and neutral conductors of the co_r 40 of alternating current line of Figure 1 to the output terminals 58 and 62. The two screws 69 and / or nuts 71 may have different colors (e.g., applying a nickel plating to a brass nut or screw) to visually distinguish the line terminals and the one from the other. A cavity 72 within the wiring chamber cover 16 provides an enclosure for the nut plates 64 and 66 and for the exposed ends of the line cord conductors when the cover is provided. 16 of the wiring chamber is secured to the rear cover 12 of Figure 1. An opening 74 of increasing configuration is provided at the bottom of the wire chamber cover 16 to allow the line cord 40 of Figure 1 passes out of the 10 GFCI plug, and a curved plastic rib 76 - in the middle of the wire chamber 72 bears against the line cord 40 to provide stress relief. Two cylindrical plastic protuberances 78 and 80 are formed on either side sZ. of the rib 76 and contain holes 82 and 84, respectively, 0 to receive the threaded ends of a pair of screws (not shown). The screws are carried by the rear cover 12 and serve to releasably connect the wiring chamber cover 16 to the rear cover 12. This allows the wiring chamber cover 16 to be separated from the rear cover 12, so that the line and neutral conductors of the line cord-40 of Figure 1 can be attached to the plates 64 and 66 of nut and allows the cover 16 of wiring chamber then # is affixed back to the back cover 12 to enclose the wiring chamfer ra 72. Figure 4 is an elevation view illustrating the interior of the rear cover 12 that has been removed from the GFCI plug 10 in Figure 3. The rear cover 12 defines a cavity 86 that houses the components carried by the board 42 and closes the wiring chamber 72 when the rear cover 12 is attached to the front cover 14 and the cover # 16 of wiring camera, respectively. In the upper portion of the cavity 86 there are two vertical slots 88 and 90 through which the plug blades 22 and 24, respectively, pass to reach the outside of the GFCI plug 10. Between the slots 88 and 90 there is an earthing band 92 extending vertically in the cavity 86 and carrying the grounding pin 26 of Figures 1 and 2 at its upper end. A retainer 94 of generally T-shaped plastic is held in contact with the upper end of the band • 0 92 grounding and serves as a spacer between the grounding band 92 and the relay and plunger coil assembly 48 of Figure 3 when the 10 GFCI plug is fully crimped. At its lower end, the grounding band 92 terminates in a nut plate 96 which is generally similar to the nut plates 64 and 66 of Figure 3. A screw 98 passes through a guidewire. not shown) in the nut plate 96 and engages a nut 100 on the opposite side of the nut plate, - identical to the way in which the screws and nuts are removed by the nut plates 64 and 66 of the nut. Figure 3. The screw 0 98 and the nut 100 are used to connect the bare end - of an earth conductor of the line cord 40 of Figure 1 to the ground band 92 of Figure 4. This provides electrical continuity between the ground pin 26 of Figures 1 and 2, and the ground conductor of the line cord 40. The nut plate 96 of Figure 4 is received between a pair of walls 102 of • and 104 vertical plastic that are integrally formed inside the rear cover 12. The walls 102 and 104 serve to position the nut plate in the proper position and to prevent contact between the nut plate 96 and the adjacent nut plates 64 and 66 of Figure 3 when the GFCI plug 10 is fully assembled. . Additional, integral, plastic walls 106 and 108 are provided in parallel relation, spaced with the walls 102 and 103 in order to trap and position the nut plots 64 and 66 of Figure 3. during the attachment of the line , the neutral and teirra conductors of the line cord 40 of Figure 1 to the GFCI plug 10, the square nuts 71 (visible in Figure 5) carried by the nut plates 64 and 66 of Figure 3 are prevented from rotating. with screws 69 through walls 110, 112, 114, 116 of plastic, respectively 5 which are carried by plastic walls 102, 103, 105 and 108 respectively. Similar transverse walls (not visible in Figure 4) are provided to restrict the nut 100.

* Also visible in Figure 4 is a curved plastic rib 118 that is similar to the rib 76 of the Figure 3 and which bears against the opposite side of the line cord 40 when the GFCI plug 10 is fully assembled . A semicircular opening 120 is provided at the bottom of the rear cover 12 and coincides with the opening 74 of Figure 3 to provide the opening for the line cord 40 on the bottom of the GFCI plug 10. In order to seal the cavity 86 with With the entrance of water or moisture, the rear cover 12 of Figure 4 includes a horizontally extending cavity 122, which coincides with a similar cavity 124 formed by a plastic structure at the bottom of the front cover 14 in the Figure 3. When the back cover 12 and the front cover 14 meet, the cavities 122 and 124 together form a closed chamber through which the output terminals 58 and 62 of Figure-3 and the ground band 92 of Figure 4 pass. A circular hole 126 in the rear wall of the rear cover 12 provides communication between this chamber and the outside of the GFCI plug 10, and an encapsulation compound is injected through the hole 126 to fill the chamber during assembly of the - 10 plug of GFCI. This provides effective sealing of the lower portion of the cavity 86 of Figure 4 when the GFCI plug-10 is fully assembled. A smaller hole 128 in the opposite side of the chamber from the hole 126 provides ve tilation for the chamber 122, 124, during the injection of the encapsulation compound. At the bottom of the rear cover 12, a pair of cylindrical protrusions 130 and 132 are formed in positions corresponding to those of the cylindrical protuberances 78 and 80 of Figure 3. The holes 134 and 136 are formed in the protuberances 130 and 132 cylindrical, respectively, and these holes extend to the rear surface of the back cover 12 to receive the head portions of the screws (not oyster * das) mentioned above. These screws couple the threaded holes 82 and 84 in the cylindrical protuberances 78 and 80 of the shroud 16 of the wiring chamber in Figure 3 to releasably secure the wiring chamber cover 16 to the back cover 12. Figure 5 is an enlarged perspective view of the circuit board 42 of Figure 3, shown separated from the front OJ 14 and, Figures 6A and 6B are elevational views of the upper portion of the circuit board 42 illustrating the closed and open positions, respectively, of the relay contact assemblies 44 and 46. These Figures illustrate two significant features of the GFCI plug 10, namely, the novel construction of the relay contact sets 44 and 46 and the space saving arrangement of the components on the circuit board 42. The relay contact assemblies 44 and 46 are substantially identical to each other, even though the corresponding components are each mirror images of each other to provide a symmetrical arrangement around the vertical midline of the circuit board 42 as shown in FIG. Figure 5. Referring first to the contacting assembly 44 - a fixed contact is provided by means of a structure that is integral with the plug blade 22. The structure includes the plug blade 22 itself, an intermediate portion that is bent at an angle of approximately -90Q with respect to the plane of the plug blade 22 and, a po_r contact support 140 that is bent at an angle of approximately 90Q from the intermediate portion 138. The intermediate portion 138 is parallel to the plane of the circuit board 42 and is secured to the circuit board 42 by means of a rivet 142. The plane of the contact support portion 140 is orthogonal to those of both., the intermediate portion 138 and the plug blade 22, as shown and, extend outward in a direction normal to the plane of the circuit board 42. As will be evident, the plug blade 22, the intermediate portion 138 and the contact support portion 140 can be formed from a continuous strip of metal that is bent at 90 ° along two fold lines. The contact support portion 140 is an electrical contact 144 of disk configuration on its surface facing upwards. Also, attached to the circuit board 42 by means of a second rivet 136 placed outside and slightly below the rivet 142, there is a cantilevered resilient arm having a base portion 148 and an elastic or deflectable portion 150. The base portion 148 is secured to the circuit board 42 by the rivet 146 and is flat against the circuit board and the elastic portion 150 is bent at an angle of 90Q with respect to the base portion so that it is initially extends outward in a direction -normal to the plane of the circuit board 42. The elastic portion 150 is then bent through an arc of 90s, as shown, so that its largest portion extends toward the midline - * vertical of the circuit board 42 with its inner edge parallel to the plane of the circuit board 42 and its bottom surface in overlying relationship with the contact support portion 140 of the fixed contact structure. The elastic or deflectable portion 150 of the spring arm terminates at a free end 152 that deflects up and down through the actuator 50 in a manner to be described later. At an intermediate point between the base portion 148 and the free end 142, the deflectable portion 150 of the spring arm carries on its surface # 0 gives down a disc configuration contact 154 which is placed in a superimposed relationship with the upwardly directed contact 144, carried by the contact support portion 140 of the fixed contact structure. The construction of the relay contact assembly 46 is essentially identical to that described above, except that the components are embedded in a mirror-like manner. Integral with the plug blade 24 are an intermediate portion 156 which is fixed to the circuit board 42 by means of a rivet 158 and a contact support portion 160 which is carried by the intermediate portion 156. The spring arm of the relay contact set 46 includes an ablation portion 162 that secures to the circuit board 42 by means of a rivet 164, and an elastic or deflectable portion 166 terminating at a free end 168, the latter being in contact with the bottom of the actuator 50.

A disk configuration contact 170 carried by the portion - • Contact contact 160 of the fixed contact structure is placed in opposite relation with a similar disc-shaped contact 172 carried on the lower surface of the elastically or deflectably portion 166 of the spring arm. The actuator 50 of Figures 5, 6A and 6B is formed with rounded, downwardly extending shoulders 171 and 173 that bear against the respective free ends 152 and 168 of the spring arms. The actuator 50 is part of a one-piece plastic structure that also includes a cylindrical spacer 174 and a lower stop member 176 similar to horizontal bar. The actuator 50, spacer 174 and stop member 176 are brought as a unit by the plunger 178 of a relay coil 180. The relay coil 180 is housed within a U-shaped metal frame 182 which, together with a corresponding metal cover 184, concentrates the magnetic flux lines within the core 180. When the coil 180 is energized by an electric current (as will occur during normal operation In the absence of an earth leakage condition, the metal plunger 178 is attracted to a magnetic core piece 188 which is secured to the bottom of the metal frame 182 and projects upwards from a distance. cuts to the coil core 180. When this occurs, the actuator 50 is pulled down as shown in Figure 6A, thereby deviating the elastic portions 150 and 166 of the restraint arms 5 to carry the contacts 154 and 172 of relay higher towards • contact with lower contacts 144 and 170. This closes both sets 44 and 46 of the relay contact and completes a circuit between each of the corresponding outlet blades 22 and 24 and terminal 58 or -62, when the current is removed from the relay coil 180; piston 178 and actuator 50 move upwardly under the restoring force of the elastic portions 150 and 166 of the spring arms, until these components assume the positions shown in Figure 6B. In this condition, the upper relay contact disks 154 and 172 are 0 separated from the lower relay contact disks 144 and 170, thereby opening both relay contact sets 44 and 46 and breaking the circuit between each blade 22 and 24 of plug and its corresponding output terminal 58 or 62. It will be seen from Figure 6B that the contact occurring between the lower stop member 176 and the lower surfaces of the contact support portions 140 and 160 of the fixed contact structures 1 im_ the upward stroke of the plunger 178 and actuator 50. This has a number of advantages. First, it helps to limit the size - of the magnetic space that may exist between the bottom of the piston 0 178 and the top of the magnetic core peg 188 and, in this way, ensures that the piston 178 will respond appropriately when the relay coil 180 it is energized Secondly, diming the components in such a way that the stop member 176 impinges on the lower surfaces of the portions 140 and -5 160 of the contact support before the elongated portions 150 and 166.

When the spring arms have deflected fully upward, a certain amount of preload force can be maintained on the spring arms when the relay contact sets 44 and 46 are in the open position shown in Figure 6B. It maintains the actuator 50 in contact with the free ends 152 and 168 of the spring arms at all times, which adjusts the space between the contact disks of each relay contact set 44 and 46 and provides more positive control. through the - movement of the spring arms.

As will be apparent from FIGS. 6A and 6B, the flanges 171 and 173 of the actuator 50 abut against the respective free ends 152 and 168 of the elastic portions 150 and 156 of the spring arms at a considerable distance from the locations of the spring arms. the upper contact discs 154 and 172. This allows some degree of overrun by the actuator 50 when the plunger 178 moves in the downward direction, exceeding the amount of travel actually necessary to carry the upper contact discs 154 and 170 in contact with the lower contact diodes 1440 and 170. This is advantageous because of 0 at least two reasons. First, the overtravel produces an additional degree of deviation of the elastic portions 150 and 166 of the spring arms in the regions between the upper contact discs 154, 172 and the free ends 152, 168. This additional deviation increases the closure or retention force that is applied between the upper contact disks 154, 172 and the disks. , ^ _ ^ cos 144, 170 lower contact. The second advantage is that, in case the gaps between the line side contact disks 144, 154 and the neutral side contact disks 170, 172 are different when the relay contact sets 44 and 46 are in In the open position of Figure 6B, overtravel of the actuator 50 will compensate for this difference and ensure that both sets of contacts are completely closed. Other advantages of the present invention will also be apparent from Figs. 5, 6A and 6B. For example, the relay contact pads 44 and 46 are relatively compact in construction, requiring only a small amount of space near the upper end of the printed circuit board 42. Both the fixed and movable contact structures of each relay assembly 44, 46 are mounted directly to the board of circuit I 5 inmate 5, an arrangement that is considerably simpler and more compact than the alternative of mounting a self-contained DPST relay in the board 42 of circuit. Finally, the cost and complexity The number of the relay contact assemblies 42 and 46 is further reduced by forming the contact structures 138, 140 and 156, 160 integrally fixed with the respective blades 22 and 24. In other circumstances, this latter feature could be disadvantageous in that the deflection of the blade blades 22 and 24 (which typically occurs in a horizontally inward or outward direction) could result in movement of the supporting portions 140 and 160. of contact of co_n structures fixed touch. In the illustrated embodiment, however, the encapsulation compound 30 of Figure 2 substantially prevents any deviation of the plug blades 22 and 24 from being transmitted to the corresponding contact bearing portions 140 and 160. The mechanical locations of the rivets 142 and 158 at intermediate points between the socket blades 22 and 24 and the contact support portions 140 and 160 also tend to insulate the contact support portions 140, 160 from any deviation J. of the blades 22 and 24 of plug. Additionally, even when the plug blades 22 and 24 are biased in a direction horizontally inwardly or outwardly, and this deflection is to some extent transposed to the contact support portions 140 and 160, the that the planes of the contact portions 140 and 160 are parallel to the direction of the deviation element means that the space between the respective pairs of contact disks 144, 154 and 170, 172 will not be affected. In general, this will be the case as long as the planes of the contact support portions 140 and 160 are orthogonal to the planes of the plug blades -22, 24 and parallel to the direction in which they deviate. the plug blades 22, 24. As can be seen from Figure 5, the main components of the GFCI plug 10 are arranged in a tandem or in line manner on the circuit board 42, with the plug blades 22, 24 at the top, the terminals - 25 td, 62 outgoing in the background and the contact assemblies 44, 46 of * re, the relay coil 180 and the toroidal transformers 52, 54 arranged linearly therebetween. This arrangement is relatively compact and provides spaces on either side of the talker 42 for the resistors, capacitors, integrated circuits and other electrical components required to detect ground loss and control the energization and deactivation of the relay coil 180. A particularly advantageous arrangement, which is employed in the illustrated embodiment, is to mount the # power supply components on the upper portion of the circuit board 42 (near the relay coil 180 and the relay contact assemblies 44, 46) and mount the integrated circuits and other sensitive components on the lower part of the circuit board 42 to isolate them from the interference caused by the operation of relay coil 180 and sets 44, 46 relay contact. In FIGS. 5, 6A and 6B, the electrical components carried by the circuit board 42 are designated individually to correspond with the reference numbers. # cia used in the schematic diagrams of Figures 7 and 8, so that the preferred positions of the components will be evident. speakers Figures 7 and 8 are schematic diagrams of two alternative electronic circuits that can be employed in the GFCI plug-10 of Figures 1-6. The circuit of figure 7 incorporates a particularity of automatic adjustment, in which the conjun¬ to 44 and 46 relay contact always close automatically that energy is applied to the AC input terminals. The circuit of Figure 8, on the other hand, requires manual adjustment to close the relay contact assemblies 44 and 46 when the GFCI plug 10 is initially connected to a C.A.-receptacle. or after a power supply interruption. Referring first to Figure 7, the automatic adjustment circuit -200 includes a pair of inlet terminals 22 and 24 corresponding to the plug blades of the GFCI plug 10. The line input terminal 22 is connected through the relay contact assembly 44 to the line conductor 56, and the neutral input terminal 24 is connected through the relay contact set 46 to the neutral conductor 60. The line and neutral conductors 56 and 60 are connected to the output terminals 58 and 62, respectively. A transient voltage suppressor 202 is connected through the input terminals 22 and 24 to provide protection from voltage parasites due to ignition and other transient conditions. The output terminals 58 and 62 are connected, respectively, to the line input terminals and over an alternating current load (not shown) through the line cord 40 of FIG. 1. The established conveying paths. by conductors 56 and 60 are selectively made and broken by the first and second relay contact assemblies 44 and 46, respectively, in order to selectively connect and disconnect input terminals 22 and 24 from the terminals. * 58 and 62 exit signals. The relay contact assemblies 44 and 46 are operated simultaneously by the alternating current coil 180. The energization of the relay coil 180 causes both relay contacts 44 and 46 to be retained in the position shown in FIG. 6A, establishing continuous conductive paths between the input terminals 22, 24 and the terminals 58. 62 output and delivering power from the alternating current source 204 to the load. When the relay coil 180 is deactivated, the relay contact assemblies 44 and 46 * 10 read both to the open position shown in Figure 6B, interrupting from this year the conductive trajectories 56 and 60 and eliminating the AC power of the load. The relay coil 180 is deactivated in response to the detection of a ground fault condition, in a manner that is further described and prevents an electric shock hazard by immediately and simultaneously removing the energy from both sides of the ground. load of - alternating current when this condition is detected. When the relay contact assemblies 44 and 46 are - in the closed position, the alternating current line and the , 56 and 60 neutrals are connected through a de-bypass path comprising a diode 206, LED 208 and current limiting resistor 210. The illumination of the LED 208, which is visible through the slow 38 of FIG. 1, provides a visual indication that the relay contact assemblies 44 and 46 are closed and that energy is available from source 204 of co-- * alternating current. When the occurrence of a ground loss condition causes the relay contact assemblies 44 and 46 to open, the LED 208 is no longer illuminated. If desired, a neon bulb can be replaced by LED 208. The detection of a ground loss condition is implemented by a current sensing circuit comprising two transformers 52 and 54, a commercially available GFCI controller 212 and various components of interconnection. The GFCI controller 212 is preferably an Type 0 RV4145N integrated circuit manufactured by Semiconductor Division of Raytheon Company, located in Mountain View, California. The GFCI controller 212 is activated from the alternating current input terminals 22 and 24 by means of a full wave power supply comprising a diode bridge 214, a current limiting resistor 216 and a capacitor 218. of filter. The positive output of the filter bridge 214 is also connected to one side of the relay bank 180 and, a diode 217 prevents the capacitor 218 from dis¬ # Charge through coil 180 of relay. A capacitor 210 proposes noise filtering through the outputs of the diode bridge 214-0. The line and neutral conductors 56 and 60 pass through the magnetic cores 220 and 222 of the transformers 52 and 54, as shown, with the secondary coil 224 of the transformer 52 being connected to the GFCI contractor input 212 and the secondary coil 226 of the transformer 54 being connected in between the GFCI controller 212 and the blackout output terminal - of the diode bridge 214. The transformer 52 serves as a differential transformer for detecting a connection between the line side of the alternating current load and a ground (not shown), while the transformer 54 serves as a neutral transformer grounded to detect a connection between the neutral side of the AC load and a ground. In the absence of an earth leakage, the currents flowing through the drivers 56 and 60 will be the same and opposite and no net flux will be generated in the core 220 of the difference transformer 52. In case a connection occurs between the line side of the AC load and ground, however, the current flowing through the leads 58 and 60 will no longer cancel accurately and a net flow will be generated in the No. 220 of the transformer 52. This flow will result in a potential at the output of the coil 224 - secondary and this output is applied to the inputs of the controller 212 of GFCI to produce a trigger signal on the output line 221. If the ground loss condition results from the neutral side of the AC load that is accidentally connected to ground, a magnetic path is established between the differential transformer 52 and the neutral transformer 54 connected to -ground. When this occurs, a positive feedback loop is created around an operational amplifier within the GFCI controller 212 and the resultant oscillations of the amplifier will also result in the trigger signal on the line 221. Since the GFCI controller 212 it's a component - commercially available, its operation is well known and does not need to be described in detail. By using this device, a resistor 225 serves as a feedback resistor for adjusting the gain of the controller and, therefore, its sensitivity to normal faults, and a capacitor 223 in parallel with resistor 225 provides noise filtering. The capacitors 227 and 228 provide noise filtering at the inputs of the controller, and capacitor 230 provides an input coupling of C.A. The capacitor 232 serves as a portion of the oscillatory circuit for the neutral transformer 54 connected to the rod. In the absence of a ground loss condition, no output is produced by the GFCI controller 212 on line 221. Under these circumstances, the current flows from the full wave power supply formed by the diode bridge 214, resistor 216. and filter capacitor 218 and then passes through the tripping circuit to provide a signal input to an additional circuit that controls the energization of the relay coil 180. The trip circuit comprises a resistor 234 of limitation connected to the positive terminal of the filter capacitor 218, a momentary normally open push button switch 36 corresponding to the RESET switch 36 of FIG. 1 and, a switching or bypass circuit. in the form of a silicon-controlled rectifier 236 (SCR) that pulls its anode connected to the mechanical circuit breaker, in that * Power loss condition does not restore power to the AC load until the manual reset button is pressed. In the circuit of Figure 7, the momentary oppression of the RESET pressure button 36 will create a short circuit across the anode and cathode of the SCR 236, causing the SCR 236 to stop current conduction. When the RESET push button 36 is released, the SCR 236 will remain in a non-conductive state in the absence of a new pulse signal. This restores the control signal to the relay coil circuit and - 0 reactivates the relay coil 180, thereby closing the relay contact assemblies 44 and 46 and restoring the alternating current energy to the terminals 58 and 62 of the relay. load or output. As noted above, the node 238 between the station 234 and the anode of the sCR 236 corresponds to the input of a unit 5 controlling the energization of the relay coil 180. This circuit includes resistors 242 and 244, which are connected in series between the node 238 and the negative output of the bridge 214 of # diode to form a voltage divider. The node 246 between the two resistors is connected to the component input (G) of a metal-oxide field-effect transistor oxide (MOSFET) 248 and, the source terminal (S) of the MOSFET 248 is connected ta to the negative output of the diode bridge 214. The drain terminal (D) of the MOSFET 248 is connected to one side of the relay coil 180 and, the opposite side of the relay coil 180 is connected to the positive output of the diode bridge 214 as an anode. * previously. In this way, when the MOSFET 248 is driven towards induction, the alternating current will flow through the relay coil 180 and will keep the relay contact assemblies 44 and 46 in a closed position. When the relay coil 180 is deactivated by the non-conductive MOSFET 248, the relay contact assemblies 44 and 46 will be opened to eliminate the energy of the alternating current load. The cyclical disconnection of the MOSFET 248 in the winding coil circuit is focused on the voltage at node 246 in the three resistors 42 and 244 voltage dividers and, this voltage in turn d = -:: •: r; The presence of the control signal at the input node 238 of the relay coil circuit is determined by the state of the SCR 236 of the trip circuit. The values of the resistors 242 and 244 voltage dividers are selected so that the appropriate gate voltage is applied to the MOSFET 248 when the control signal is present. A filter capacitor 250 is connected between the gate terminal of the MOSFET 248 and the negative output of the diode bridge 214 in order to prevent the MOSFET 248 from cycling cyclically by noise imputation. A resistor 252 and diode 254 enable the capacitor 250 to discharge quickly when the SCR 236 goes into conduction - thereby enabling a rapid disconnection of the MOSFET 248. A capacitor 256 is connected between the drain and source terminals of the MOSFET 248 in order to prevent the MOSFET 248 is disengaged toward driving by rapid changes in the voltage of * drain-to-source, a phenomenon known as dV / dT triggering. In addition to the RESET switch 36, a second momentary normally open momentary push button switch 34 is provided to allow the user to test the operation of the GFCI plug 10. The test switch 34 is connected in series with a current limiting resistor 258 and, the series connection of the switch 34 and resistor 258 is connected between the conductor 56 of the alternating current line on the load side of the transformers. 52 and 54, and the neutral conductor 60 alternates on the supply side of the transformers 52 and -54. When the TEST switch 34 is momentarily depressed, sufficient current will flow through the resistor 258 to cause an imbalance in the current flowing through the primary coil of the transformer 52. This will simulate a ground loss condition 5, causing the GFCI controller 212 to produce an output signal on the line 221 which deactivates the relay coil 180 by making the SCR 236 driver and MOSFET 248 non-driver. Relay contact assemblies 44 and 46 will open, and can be closed again by pressing switch 36 of REA0 JUSTE. If this sequence of events does not occur, the user will be alerted to the fact that the GFCI plug 10 is defective and requires repair or replacement. Figure 8 is a schematic diagram of a modified circuit 270 for the GFCI plug 10 incorporating a manual adjustment part. Except for the particularity of # manual adjustment, the circuit of Figure 8 is similar to that of Figure 7 and the components thereof have been numbered correspojpiently. The particularity of manual adjustment, which is described in the aforementioned copending patent application - by Thomas M. McDonald, Serial No. 08 / 115,020, requires that the GFCI-plug 10 be manually adjusted by depressing the reset switch 36 when the GFCI plug 10 is initially connected to the alternating current power supply 204, or after an interruption in the alternating current energy SJJ 0 minitrada. This is achieved, in part, by means of a controlled switching device 272 which is collated in series between the resistor 234 and the node 238, as illustrated in FIG. 8, in order to selectively apply the control signal of the control circuit. Stopped the resistors 242 and 244 voltage dividers of the relay coil circuit 5. In the illustrated embodiment, the controlled switching device 272 comprises an opto-isolator 272. The control or input circuits 274 6 276 of the opto-isolator 272 are connected to an internal light-emitting diode (LED) 278 which allows the current to flow between the terminals 280 and 282 of outlet-0 of the optoisolator when the LED 278 is deflected forward. In the circuit of Figure 8, the input terminals 274 and 276 of the opto-isolator are connected through the load or output terminals 58 and 62 of the GFCI plug 10 in order to form a charge energy charging circuit for detect the availability of alternating current power in the terminals of - load. The diode 206 is placed in series between the alternating current line output terminal 58 and the positive optoisolator input terminal 274 for limiting the reverse deviation potential through the LED 278. A resistor 286 is placed on the ground. between the diode 284 and the LED 278 to limit the current flow through the LED 278. The LED 208 of Figure 7 (which is replaced by a neon bulb if desired) is placed in series between the resistor 286 and the LED 278 in the circuit of FIG. 8 and illuminates as long as the alternating current energy is available at the load terminals 58 and 62. The momentary pushbutton switch 36 is connected through the output terminals 280 and 282 of the optoisolator 272 as shown. The momentary pressure button 36 is normally open andWhen pressed, it establishes a short circuit between the resistor 234 and the node 238 in order to derive the optoisolator 272. A capacitor 283 is connected in parallel with the switch 36, as shown In the absence of a ground loss condition, the - control signal current flowing from the resistor 234 passes through the optoisolator 272 to the node 238 and voltage dividing resistors 242 and 244, thereby making the conductive MOSFET 248 and energizing the relay coil 180 so as to to maintain - the relay contact assemblies 44 and 46 in the closed position. When the closed relay contact assemblies 44 and 46, the current of the AC power source 204 flows through the diode 284, resistor 286 and LEDs 208 and 278, provide In this way, a charge energy signal maintains the optoisolator 272 in a conductive state as long as the power is being made available at the load terminals 58 and 62. (The optoisolator 272 actually conducts only during the rn gave positive cycles of the alternating current potential at the load terminals 58 and 62, but the capacitor 250 is of sufficient size to maintain the MSFET 248 in conduction during the short intervals in the that the optoisolator 272 is not driving). When a ground loss condition is detected by the GFCI controller 212, the MOSFET 248 becomes non-conductive - when the SCR 236 is connected cyclically to conduction and deactivates the relay coil 180. This causes the relay assemblies 44 to open, thereby removing the energy from both sides of the alternating current load. The opening of the relay contact assemblies 44 and 46 also eliminates the energy of the input terminals 274 and 276 of the optoisolator 272, thereby causing the optoisolator 272 to become non-conductive and the SCR 236 to turn off. The termination of the ground loss condition will not readjust to the GFCI plug 10, since 0 the current can not flow to the reel coil 180 until the optoisolator 272 has been restored to a conductive state. The reset is achieved by momentarily pressing the reset switch 36, which drifts to the optoisolator 272 and allows the corried to flow through the relay coil 180 for a period of time to close the contact assemblies 44 and 46. relay.

* As soon as the contact assemblies are closed, the energy is applied again to the input terminals 274 and 276 of the insulator 027, which places the optoisolator 272 in conduction, the RESET button 36 can then be released without causing - the relay contact assemblies 44 and 46 are opened. The capacitor 283 helps retain the optoisolator 272 in conduction during this interval. Since the ground loss condition has been terminated, SCR 236 is no longer cycling cyclically -? by the output 221 of the GFCI controller 212 and, therefore, the The current flowing through the reset switch 36 or opto-isolator 272 is not derived to the negative output of the diode bridge 214. However, if the readjustment is treated while all of the earth loss condition is in effect, the SCR 236 will start to drive since it is still relying on a cyclic disconnect signal from the GFCI controller 212. Therefore, the current passing through the reset or opto-isolator switch 362 will be derived directly to the nega- tive output of the diode bridge 214 by the SCR 236 and, the potential at the node 238 will be insufficient for activate coil 180 of relay. The manner in which the GFCI circuit 270 of FIG. 8 provides a particularity of manual rejouting by following the initial connection to an alternating current power supply, or termination of a power supply interruption, - 5 will now be evident. Since terminals 274 and 276 of in-- * The opto-isolator 272 are connected (through the diode-284, resistor 286 and LED 208) to the neutral line conductors 56 and 60 on the load side of the relay contact assemblies 44 and 46, will not be activated. less than medium power is supplied to the alternating current source 204 and the contact assemblies 44 and 46 are closed. The contact assemblies 44 and 46, in turn, can not be closed until the current is initially supplied to the relay coil 180 by operating the reset switch 36 to position the optoisolator 272 in conduction. In another 0 words, after the plug blades 22 and 24 of the GFCI plug 10 are initially connected to an AC receptacle, the alternating current energy will not appear at the output terminals 59 and 62 until the button 36 of RESET pressure is pressed momentarily. Similarly, an interruption in the alternating current energy from the source 204 will remove the power from the output terminals 58 and 62 - deactivating the relay coil 180 for a sufficient period of time. * to allow the contact sets 44 and .46 to open and, this will cause the optoisolator 272 to become nonconductive. 0 The energy will not be restored until the RESET switch 36 is momentarily depressed to close the contact assemblies 44 and 46 and, thus, return the optoisolator 272 to a conductive state. In both of the situations just described (ie, initial connection to an AC power source and a temporary interruption of the power source) 32 AC power), the LED 208 will not illuminate until the AC power becomes available at the load and output terminals 58 and 62. In this way, the non-illumination of the LED 208 serves not only to indicate that a ground loss occurred, as in the circuit of Figure 7 but also indicates when it is adjusted in the manual of the plug 10 GFC is needed in order to provide alternating current power to the output terminals 58 and 62. The optoisolator 272 of Figure 8 may adopt a variety of forms. In the embodiment shown, the portion of the opto-isolator 272 through which the controlled current flows comprises a phototransistor, with the output terminals 280 and 282 comprising the collector and emitter terminals, respectively the phototransistor. In other embodiments, however, this portion of the opto-insulator may comprise a thyristor, such as a controlled-duty rectifier (SCR) or a triac, or a field effect transistor (FET). Either of these devices - * may be used in place of the optoisolator 272 shown in FIG. 8. The desirable feature of all these devices is 0 to provide electrical isolation between the output terminals 58 and 62 and the internal control circuit of the device. 10 plug of GFCI. In this way, a fault or defect in the internal circuit of the GFCI plug 10 can not cause the ends 58, 62 and 62 of the load to be connected to the source 204 of the circuit 5 when the contact assemblies 44 and 46 are connected. of relay are »In the open position. This is a desirable security feature in a GFCI device. Other methods to achieve the desired isolation, including the use of relays and triacs cyclically disconnected by transformer, are described in the above-mentioned co-pending application to Thomas M. McDonald, Serial No. 08 / M5.020, which is incorporated in the present by reference. Also described in the copending application is an additional modifications in which the reset switch 36 is relocated in a manner that restores the optoisolator 272 to the non-conductive state by temporarily deriving the output terminals of the opto-isolator as in FIG. 8, but instead, temporarily activating the input terminals 274 and 276 of the optoisolator 272 from the alternating current input terminals 22 and 24. Preferred values will give the electrical components 5 used in circuits 200 and 270 of GFCI of Figures 7 and 8 are given in Table 1 below. The values of • Sjk resistor is expressed in ohms (o), iloohms (K) or megohms 0M). All resistors are 1/4 watt unless otherwise noted. Capacitor values are expressed in micro farads (uF) or picofarads (pF). * box 1 Component Value or Type Resistors 215, 258 15K Diodes 206, 214, 217, 254 1N4005 LED 208 Red (or neon bulb) Resistor 210 47K Resistor 216 15K (2. watts) Capacitors 218, 240, 250 3.3 uF Capacitor 219 0.01 uF (500 volts min.) Capacitor 223 22 pF (50 volts) Resistor 225 1.0 M Capacitor 227 0.01 uF Capacitor 228 0.001 uF Capacitor 230 10 uf (50 volts) Capacitor 232 0.01 uF Resistor 234 2200 0 SCR 236 Teccor EC 103 Resistors 242, 244 22 MOSFET 248 Siliconix BN50300L Resistor 252 22 0 Capacitor 0.0022 uF (500 volts min.) Resistor 258 15 K Optoisolator 272 4N36 or KPC PC17T1 Resistor 286 27K (1/2 watt) or 47K for neon bulb. Capacitor 283 0.1 uF (25 volts) Figures 9A, 9B and 9C illustrate a modified construction of spring arm 148, 150 of Figures 5, 6A and 6B, and - Figure 10 illustrates a modified circuit board configuration that can be used with this spring arm. It will be understood that a similar modification can be employed for the second spring arm 162, 166 of Figures 5, 6A and 6B. In the modification, the base portion 148 'of the spring arm is along the back surface of the circuit board 42 F instead of along the front surface as shown - 10 in Figure 5. The elastic or deflectable portion 150 'of the spring arm passes through a horizontal groove 290 formed (close to the upper left hand corner of the board 42 and remains on the contact support portion 140 of the The fixed contact structure as in the embodiment of Figures 5, 6A and 6B. At the lower end of the base portion 148 ', a semicircular tongue or retainer 292 is formed and passes through an elongated hole 294 in the circuit board 42 positioned below the slot 290. During assembly, the clamping force - exerted between the slot 290 and the hole 294 by the deflectable portion 0 150 'and the tongue 292 retains the spring arm in place on the circuit board 42. As in the embodiment of Figures 5, 6A and 6B, a rivet 146 is then inserted through a hole 296 in the surgeon's board and through a corresponding hole 298 in the base portion 148 'of the spring arm 5 to permanently fix arm 148, 150 'of reso_r you to the board 42 circuit. During wave soldering of the circuit board 42, the weld is applied to the base portion 148 'and to an underlying contact pad on the reverse side of the printed circuit board 42, which additionally secures the arm 148'. , 150 'from springs to board 42 of circuit. The embodiment of Figures 9A, 9B, 9C and 10 is advantageous in that the rotation of the spring arm 148 ', 150' above the rivet axis 146 of Figures 5, 6A and 6B is mediately prevented from engaging the 150 'portion deflectable with the slot 290 and by engaging the tongue or retainer 292 with the elongated hole 294. Said rotation, which otherwise can occur with repeated deflection of the spring arm by the actuator 50, is undesirable because it can alter the space between the contact discs 144 and 154 in Figures 5, 6A and 6B. As in the embodiment of FIGS. 6A and 6b, a hole 298 is provided in the spring or deflectable portion 150 'of the spring arm to allow attachment of the upper contact disk 154. The tapered profile of the resilient or deflectable portion 150 'as shown in FIG. 9C is also shared with the fashion of FIG. 5 and, it is advantageous by reducing the deflection force necessary to close the relay contact assembly 44. . Also visible in Figure 10 is the hole 300 which is formed near the upper edge of the circuit board 42 to receive the rivet 142 of Figures 5, 6A and 6B. Even though it has only been selected to illustrate - • the present invention a. number.- 1 imitated of exemplary modalities, will be understood by those experienced in the matter that can be made in the same diverse changes and modifications. For example, the housing of the GFCI plug 10 may be provided with one or more female alternating current outputs to accommodate the plugs of the alternating current charging devices, in addition to or instead of the line cord 40. These and other changes or modifications are intended to be within the spirit and scope of the invention as defined in the attached clauses. 0

Claims (19)

CLAIMS:

1. - An earth leakage circuit interrupter plug, which comrpenses: a housing having a pair of plug blades for connection to an alternating current receptacle and a pair of output terminals for coaxial to an alternating current load. na and I electrical circuit inside the housing to provide protection against earth leakage to a current load connected to the output terminals, the electric circuit including: a relay comprising a relay coil and a pair of - relay contact assemblies to connect and disconnect selectj ^ 5 the plug blades and output terminals; and an electronic circuit coupled to the relay coil to maintain the relay contact assemblies in a closed position to connect the plug blades to the output terminals in the absence of a ground loss condition and, in order to cause The relay contact assemblies are moved to an open position to disconnect the plug blades from the output terminals in response to a ground loss condition. 2.- A loss circuit switch plug -5 to ground as claimed in clause 1, which comprises plus a circuit board inside the housing to carry the electrical circuit, the circuit board providing a mounting for the pair of relay contact assemblies. 3. A ground-fault circuit interrupter plug as claimed in clause 2, wherein each of the relay contact assemblies comprises a fixed co-tact structure mounted to the circuit board and a tactile-cushion structure. mounted to the circuit board and, wherein the relay -F further comprises an actuator controlled by the relay coil -0 to move the movable contact structure towards and away from the contact with the fixed contact structure. 4. A ground-fault circuit interrupter plug as claimed in clause 3, wherein the fixed contact is integral with one of the plug blades. 5. A ground-fault circuit interrupter plug as claimed in clause 4, wherein the fixed contact structure and the plug blade are formed from a% continuous strip of metal that is secured at an intermediate point to the circuit board, with the section of the strip on one side 0 of the intermediate point forming the fixed contact structure and the portion of the strip on the other side of the intermediate point forming the enchfue blade. 6. An earth leakage circuit interrupter plug as recited in clause 5, wherein the portion -5 of the strip forming the fixed contact structure is in a - • plane that is substantially orthogonal to the plane of the plug blade and parallel to the longitudinal axis of the plug blade. 7. A ground loss circuit interrupter plug as claimed in claim 3, wherein the movable contact structure comprises a cantilevered spring arm having an end secured to the circuit board and a free end opposite to the insured end. 8.- A loss circuit breaker plug to * 10 ground as claimed in clause 7, wherein the actuator bears on the free end of the spring arm in order to deflect the spring arm into contact with the fixed contact structure and, where the spring arm it includes a contact portion positioned at an intermediate point between the free end and the secured end to contact the fixed contact structure during said deflection. 9.- A loss circuit breaker plug to ground as claimed in the case 8, wherein the actuator is movable between a first stop position in which the spring arm is not in contact with the fixed contact structure and a second stop position in which the The spring arm is deflected to bring the contact portion thereof into contact with the fixed contact structure and, wherein the distance moved by the actuator from the first stop position to the second stop position. is greater than the distance necessary to bring the contact portion of the spring arm into contact with the fixed contact structure, whereby the closing force applied between the contact portion and the fixed contact structure is included. 10. An earth leakage circuit interrupter plug as claimed in clause 9, wherein the free end of the spring arm is elastically biased toward the actuator when the actuator is in the first position. of detention in order to maintain a preload force on the spring arm. 11. A ground-fault circuit interrupter plug as claimed in clause 2, wherein the electric circuit further comprises a pair of line and neutral conductors for connecting the plug blades to the output terminals through of the relay contact assemblies and at least one perception transformer through which the line and neutral conductors pass to perceive an imbalance of -current in the conductors that is indicative of a condition -of loss to earth and, where the relay contact assemblies the relay coil and the sense transformer are mounted on the printed circuit board in a generally tandem arrangement. 12.- An earth leakage circuit breaker plug as claimed in the case 11, where the additional components of the electrical circuit is? mounted on the ta Circuit blending along at least one side of the generally tandem arrangement of the relay contact assemblies, the relay coil and the sense transformer. 13. An earth leakage circuit interrupter plug as claimed in clause 1, wherein the plug blades and output terminals are provided at generally opposite ends of the housing. 14.- A ground-fault circuit interrupter plug as claimed in clause 1, where the terminals 10 output ports comprise screw terminals positioned within the housing for connection to an alternate line cord. 15.- A relay contact arrangement for use on a ground-fault circuit interrupter plug, 15 that comrpende: a circuit board; an integral plug blade and conta £ structure ^ r to fixed relay carried by the circuit board, a movable relay contact structure carried by 20 the circuit board; and an actuator for moving the movable relay contact structure towards and out of contact with the fixed relay contact structure. 16.- A relay contact arrangement as rei¬ 25 vindicates in clause 15, where the interconnect blade gral and the fixed relay contact structure and movable contact structure are each mounted directly to the circuit board. 17. A relay contact arrangement as claimed in clause 15, wherein the fixed relay contact structure and the plug blade are formed from a continuous strip of metal which is secured at an intermediate point to the circuit board, with the portion of the tica.on one side of the intermediate point forming the fixed relay contact structure and the section of the strip on the other side of the intermediate point forming the plug blade. 18. A relay contact arrangement as claimed in clause 17, wherein the portion of the strip that forms the fixed relay contact structure is in a plane that is substantially orthogonal to the plane of the plug blade. and parallel to the longitudinal axis of the plug blade. 19. A relay contact arrangement as claimed in clause 15, wherein the movable relay contact structure comprises a cantilevered spring arm having an end secured to the circuit board and a free end opposite the secured end . 2T.- A relay contact arrangement as claimed in clause 19, wherein the actuator rests on the free end of the spring arm in order to deflect the spring arm into contact with the fixed relay contact structure and wherein the spring arm includes a contact portion c located at an intermediate point between the free end and the secured end to contact the fixed contact contact structure during said deflection. 21. A relay contact arrangement as claimed in clause 20, wherein the actuator is movable between a first stopping position in which the restraint arm is not in contact with the fixed relay contact structure and the second stopping position in which the spring arm deviates to bring the contact portion thereof into contact with the fixed relay contact structure and, where the distance moved by the actuator of the first stopping position to the second stopping position is greater than the distance needed to bring the contact portion of the spring arm into contact with the fixed relay contact structure, whereby the closing force applied between the contact portion and the structure Fixed relay contact is increased. 2

2. A contact arrangement of re l e as claimed in clause 21, wherein the free end of the spring arm is elastically deflected into contact with the actuator when the actuator is in the first stopping position at-end of maintain a preload force on the spring arm. 2

3. A method for opening and closing the line or neutral side of an alternating current load in a ground fault circuit interrupter, comprising the steps of: pr providing a fixed relay contact structure and movable relay contact structure that is movable to and out of contact with the fixed relay contact structure, the movable contact structure being provided in the form of a spring arm in cantilever having an end secured to a free end and, a contact portion placed at an intermediate point between the secured end and the free end to make contact with the fixed contact structure; connect one of the fixed and movable relay contact structures to the line or neutral side of an alternating current source and the other of the fixed and movable contact structures - to the same side of the alternating current load; opening the line or neutral side of the alternating current load by moving the spring arm to a first stop position in which the spring arm is not in contact with the fixed relay contact structure; and closing the neutral or alternating side of the running load by applying a force to the free end of the arm to move the spring arm to a second position where the HP arm rests on the arm.; s \ t? Nara i l ° var the contact portion thereof in contact with the fixed relay contact structure; wherein the distance moved by the free end of the spring arm from the first stopping position to the second stopping position is greater than the required distance - to bring the contact portion of the spring arm into contact with the fixed relay contact structure, whereby the closing force applied between the contact portion and the fixed relay contact structure is increased. 2

4. A method as claimed in claim 23, which further comprises the step of maintaining a pre-sealing force on the spring arm by elastically deflecting the spring arm towards the fixed relay contact structure while the spring arm He is in the first detention position. 0