Abstract:
An improved ground-fault circuit interrupter (GFCI) device has a moveable lock plate controlled by a relay to block a hole under the reset guiding member to prevent reset of the device. The moveable lock plate blocks the hole and prevents reset when the relay is not energized, and expose the hole to allow reset when the relay is energized. The relay is powered by a power supply circuit which is connected in series with a solenoid across the input side of the GFCI. The solenoid is controlled by a control circuit, and causes a disconnecting assembly to disconnect the input and output sides of the GFCI when a leakage current is detected. If the solenoid malfunctions, or if the GFCI device is reversely wired, the relay is not energized and the device cannot be reset.

Description:
This application claims foreign priority benefits under 35 U.S.C. §119(a)-(d) from China Patent Application No. 200620158464.6, filed Nov. 14, 2006, which is incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to leakage current protection devices, and more particularly relates to improved ground-fault circuit interrupters with a reverse wiring protection function. 
     2. Description of the Related Art 
     A receptacle type ground-fault circuit interrupter (GFCI) device with reverse wiring protection is described in commonly owned U.S. Pat. No. 7,009,473, issued Mar. 7, 2006, which is incorporated by reference herein in its entirety. This device provides both leakage current protection and reverse wiring protection that protects against incorrect wiring during installation. Such a GFCI receptacle has a pair of input terminals for connecting to power lines, a pair of output terminals for connecting to a load, and one or more insertion outlets on a faceplate of the receptacle each for receiving the prongs of a plug. When installing the GFCI receptacle in the wall, if the power lines from the wall are incorrectly connected to the output (load) side of the receptacle, the GFCI device effectively cuts off power output at the input side of the receptacle. An improved receptacle type GFCI device with reverse wiring protection is described in commonly owned U.S. patent application Ser. No. 11/484,506, filed Jul. 10, 2006, now pending, which is incorporated by reference herein in its entirety. In this improved GFCI device, if the power lines are incorrectly connected to the load side of the receptacle during installation, power output to both the input side of the receptacle and the insertion outlets on the faceplate is prevented. The GFCI receptacle includes two stationary terminals on two first output conductors electrically connected to the insertion outlet, two stationary terminals on two second output conductors adapted for electrically connecting to the load, and four moveable terminal on two moveable connector arm adapted for electrically connecting to the power lines. The four moveable terminals correspond in position to the four stationary terminals, respectively, and operate to electrical connect or disconnect the power lines to and from the load and the insertion outlet in a manner controlled by a disconnecting mechanism assembly and a reverse wiring protection mechanism. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a GFCI device that is an improvement of the GFCI device described in commonly owned U.S. Pat. No. 7,009,473 and U.S. patent application Ser. No. 11/484,506. 
     An object of the present invention is to provide a GFCI receptacle device with reverse wiring protection function, and can prevent electrical connection between the input and output sides when the disconnecting solenoid is not properly functioning. 
     Additional features and advantages of the invention will be set forth in the descriptions that follow and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides an improved ground-fault circuit interrupter (GFCI) device, which includes: input conductors adapted to be electrically connected to hot and neutral power lines; output conductors adapted to be electrically connected to hot and neutral load lines; output metal plates adapted for receiving prongs of a plug; a disconnecting assembly for electrically connecting the input conductors to the output conductors and the output metal plates when in a connected state, and electrically disconnecting the input conductors from the output conductors and the output metal plates when in a disconnected state; a solenoid which, when triggered, causes the disconnecting assembly to move from the connected state to the disconnected state; a detector coil for detecting a leakage current on the input conductors; a control circuit electrically coupled to the detector coil and the solenoid for triggering the solenoid when a leakage current is detected; a power supply circuit connected in series with the solenoid between the input conductors; a relay connected to the power supply circuit, the relay being energized when the power supply circuit has a current passing through it; a moveable lock plate coupled to the relay, the moveable lock plate being moveable between a locking position when the relay is not energized and an unlocking position when the relay is energized; and a reset mechanism coupled to the disconnecting assembly for resetting the GFCI device, the reset mechanism including a reset button and a vertically movable reset guiding member coupled to the reset button, wherein when the reset guiding member moves down and then up, it engages with the disconnecting assembly to cause the disconnecting assembly to be in the connected state, and wherein the moveable lock plate prevents the reset guiding member from moving down when the moveable lock plate is in the locking position. 
     The improved ground-fault circuit interrupter device further includes a fist pair of stationary contact terminals electrically connected to the input conductors; a second pair of stationary contact terminals electrically connected to the output metal plates; and a first pair and a second pair of moveable contact terminals electrically connected to the output conductors, wherein the disconnecting assembly moves the first and second pairs of moveable contact terminals to be in contact with the first and second pairs of stationary contact terminals, respectively, in the connected state and moves the first and second pairs of moveable contact terminals to break contact with the first and second pairs of stationary contact terminals, respectively, in the disconnected state. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exterior perspective view of a GFCI receptacle device according to an embodiment of the present invention. 
         FIG. 2  is an exploded view showing the structure of the GFCI receptacle. 
         FIG. 3  is a perspective view of the GFCI receptacle in a partially assembled state. 
         FIGS. 4 and 5  are cross-sectional views illustrating the GFCI receptacle in a proper working condition, where the input side and the output side are electrically connected. 
         FIGS. 6 and 7  are cross-sectional views illustrating the GFCI receptacle in a disconnected condition when reverse wired or when the solenoid is not properly functioning, where the input side and the output side are electrically disconnected. 
         FIG. 8  is a circuit diagram of a GFCI receptacle according to an embodiment of the present invention. 
         FIG. 9  is a circuit diagram of a GFCI receptacle according to an alternative embodiment of the present invention. 
         FIG. 10  is a circuit diagram of a GFCI receptacle according to another alternative embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in  FIGS. 1-3 , a GFCI receptacle according to an embodiment of the present invention includes a body and the following components disposed within the body: input conductors electrically coupled to input screws, output conductors, output metal plates electrically coupled to output screws for receiving prongs of a plug, a detector coil for detecting a leakage current, a disconnecting assembly for electrically connecting and disconnecting the input side and the output side, and a circuit board having a control circuit. 
     As shown in  FIG. 1 , the body includes a cover  1  and a base  2 . The cover  1  has a three-phase power outlet, a reset button  4  and a test button  5 . The reset button  4  and test button  5  pass through the cover  1  to couple to components inside the body. A pair of input screws  30 ,  33  and a pair of output screws  31 ,  32  are provided on the side of the base  2 . 
     As shown in  FIG. 2 , an insulating support frame  6  is disposed inside the body, and a metal grounding plate  3  is disposed between the cover  1  and the insulating support frame  6 . The grounding plate  3  is connected to the ground via conductors and a grounding screw  34 . A circuit board  7  is disposed between the support frame  6  and the base  2 . 
     As shown in the figures, on both sides of the support frame  6  are hot output conductor  10  and neutral output conductor  11 . On the output conductors  10  and  11  and corresponding to the outlet holes are metal insertion plates  57 ,  58 ,  59  and  60 . A stationary contact terminal  55  is provided on the hot output conductor  10  and a stationary contact terminal  56  is provided on the neutral output conductor  11 . 
     As shown in  FIGS. 2 and 3 , provided on the circuit board  7  are input conductors  20 ,  21 , detector coil  9 , moveable elastic output metal plates  14 ,  15 , and a disconnecting assembly for connecting and disconnecting the input side and the output side of the GFCI receptacle. 
     One end of the input conductors  20 ,  21  pass through the detector coil  9  to be soldered together with metal connectors  23 ,  26  on the circuit board  7 , and are electrically connected to the hot and neutral input screws  30 ,  33  via conductors. The other end of the input conductors  20 ,  21  are provided with stationary contact terminals  50 ,  51 . 
     The moveable elastic output metal plates  14 ,  15  are provided on the two sides of the circuit board  7 . One end of the moveable elastic output metal plate  14  is soldered together with metal connectors  24  on the circuit board  7 , and is electrically connected to the hot output screws  31 . The other end of the moveable elastic output metal plate  14  forks into two moveable contact arms  43 ,  42  with moveable contact terminals  46 ,  47 , respectively. The moveable contact terminal  46  corresponds in position to the stationary contact terminal  50  of the input conductor  20  to form a switch that can be opened or closed; the moveable contact terminal  47  corresponds in position to the stationary contact terminal  55  of the input conductor  10  to form another switch that can be opened or closed. Similarly, one end of the moveable elastic output metal plate  15  is soldered together with a metal connector  25  on the circuit board  7 , and is electrically connected to the neutral output screws  32 . The other end of the moveable elastic output metal plate  15  forks into two moveable contact arms  41 ,  40  with moveable contact terminals  45 ,  44 , respectively. The moveable contact terminal  45  corresponds in position to the stationary contact terminal  51  of the input conductor  21  to form a switch that can be opened or closed; the moveable contact terminal  44  corresponds in position to the stationary contact terminal  56  of the input conductor  11  to form another switch that can be opened or closed. 
     Between the input conductors  20 ,  21  and the moveable elastic output metal plates  14 ,  15 , a disconnecting assembly for connecting and disconnecting the input side and output side of the GFCI device is provided. The disconnecting assembly includes a disconnecting member  12 , an L-shaped lock member  13 , and a disconnecting coil (solenoid)  8  with a plunger  16 . 
     The disconnecting member  12  has a cylindrical shape with a though hole  62  and two side arms  53 ,  52  extending outward. The moveable elastic output metal plates  14 ,  15  are located above the side arms  53 ,  52 , respectively, and move up and down with the disconnecting member  12 . A cylindrical reset guiding member  37  is disposed inside the though hole  62  of the disconnecting member  12  (see  FIG. 2 ), and passes through the support frame  6  and metal grounding plate  3  to reach the underside of the reset button  4 . The lower end of the guiding member  37  is cone-shaped, and has a circular groove  38  above the cone-shaped end. The upper end of the guiding member  37  is coupled to the reset button  4  and can move up and down with it. A reset spring  27  is disposed around the reset guiding member  37 . 
     The disconnecting member  12  also has lateral hole  63 , where the top portion of the L-shaped lock member  13  is slideably disposed in the lateral hole  63 . Two holes  61  are provided on the top portion of the L-shaped lock member  13 , and a U-shaped slot  64  is provided on the side portion of the L-shaped lock member  13  to engage a circular groove located at the front end of the plunger  16 . The plunger is disposed inside the disconnecting coil  8 , and a disconnecting spring  28  is disposed between the rear end of the plunger  16  and the disconnecting coil  8 . 
     The two ends of the disconnecting coil  8  are connected via the control circuit on the circuit board across the input side hot and neutral lines of the GFCI device. When a current flows through the disconnecting coil  8 , a magnetic field is generated which causes the plunger  16  to move. The plunger  16  pushes the L-shaped lock member  13  coupled thereto to slide within the disconnecting member  12 . As a result, the reset guiding member  37  moves vertically in the though hole  62  of the disconnecting member  12 , bringing the disconnecting member  12  to move vertically, so that the moveable contact terminals  46 ,  45  on the moveable elastic output metal plates  14 ,  15  located above the side arms  53 ,  52  are brought into contact with the stationary contact terminals  50 ,  51  on the input conductors  20 ,  21 , and the moveable contact terminals  47 ,  44  are brought into contact with the stationary contact terminals  55 ,  56  on the output conductors  10 ,  11 . The input side and output side of the GFCI device are therefore electrically connected. 
     To prevent reverse wiring mistake, and to electrically disconnect the input side and the output side in the event of abnormal conditions in the disconnecting solenoid, a relay assembly is provided as shown in  FIGS. 2 and 5 . The relay assembly includes a relay coil  17 , a relay plunger  19 , a moveable lock plate  18  and a spring  29 . The relay plunger  19  is disposed inside the relay coil  17 , and its front end is coupled to the moveable lock plate  18  to move it. The spring  29  is disposed between the relay coil  17  and the relay plunger  19 . On the circuit board  7 , a hole  65  is provided below the reset guiding member  37  as shown in  FIG. 7 . Before the GFCI is installed, the hole  65  is initially covered by the moveable lock plate  18 . During installation, when the input side and output side of the GFCI are correctly wired and the disconnecting solenoid and other components of the GFCI device are functioning normally, the relay coil  17  is energized, generating a magnetic field to drive the relay plunger  19 . Thus, the moveable lock plate  18  is moved by the relay plunger  19  to expose the hole  65 . When the hole  65  is exposed, the reset guiding member  37  can be moved vertically inside the though hole  62  of the disconnecting member  12 . The vertical movement of the reset guiding member  37  is necessary to allow the reset button  4  to be pressed down. To reset the device, the reset button  4  is pressed down and then released. The reset guiding member  37  brings the disconnecting member  12  upwards (as the groove  38  engages the edge of the hole  61  of the L-shaped lock member  13  when the reset button is pressed down), causing the moveable contact terminals  46 ,  45 ,  47 ,  44  to contact the stationary contact terminals  50 ,  51 ,  55 ,  56 , respectively. As a result, the input side and output side of the GFCI device are electrically connected. The hole  65  remains exposed and the GFCI device can be repeatedly reset after trips as long as all components of the control circuit function properly. 
     As shown in  FIGS. 8 ,  9  and  10 , the two ends of the relay coil  17  are connected to the DC output or AC input of a power supply circuit (the diode bridge) that supplies power to the GFCI control circuit. At least one end of the relay coil  17  is connected after the solenoid SOL (i.e. the disconnect coil  8 ). The solenoid is connected in series with the power supply circuit. 
     As shown in  FIG. 8 , the hot line (HOT) of the input side (LINE), a diode bridge rectifier circuit D 1 -D 4 , the solenoid SOL, and the neutral line (WHITE) of the input side (LINE) are connected in series to form the power supply circuit that supplies power to the GFCI control circuit. One end of the relay coil  17  is connected via a resistor R 3  to the positive DC output of the diode bridge rectifier circuit D 1 -D 4 . The other end of the relay coil  17  is connected after the solenoid SOL to the input of the diode bridge rectifier circuit D 1 -D 4  that is connected to the negative DC output of the diode bridge rectifier circuit D 1 -D 4 . 
     As shown in  FIG. 9 , the hot line (HOT) of the input side (LINE), a diode bridge rectifier circuit D 1 -D 4 , the solenoid SOL, and the neutral line (WHITE) of the input side (LINE) are connected in series to form the power supply circuit that supplies power to the GFCI control circuit. One end of the relay coil  17  is connected via a resistor R 5  to the positive DC output of the diode bridge rectifier circuit D 1 -D 4 . The other end of the relay coil  17  is connected after the solenoid SOL to the negative DC output of the diode bridge rectifier circuit D 1 -D 4 . 
     As shown in  FIG. 10 , the hot line (HOT) of the input side (LINE), a diode bridge rectifier circuit D 1 -D 4 , the solenoid SOL, and the neutral line (WHITE) of the input side (LINE) are connected in series to form the power supply circuit that supplies power to the GFCI control circuit. One end of the relay coil  17  is connected to the input of the diode bridge rectifier circuit D 1 -D 4  that is connected to the hot line (HOT) of the input side (LINE). The other end of the relay coil  17  is connected after the solenoid SOL to the input of the diode bridge rectifier circuit D 1 -D 4  that is connected to the neutral line (WHITE) of the input side (LINE). 
     As shown in  FIGS. 8 ,  9  and  10 , when the solenoid SOL is not conductive due to an abnormal condition, the current path of the power supply circuit formed by the diode bridge rectifier circuit D 1 -D 4  and the solenoid is broken. Thus, no voltage is applied on the relay  17 , no current flows through the relay to generate a magnetic field, and the plunger  19  is not activated. As such, the moveable lock plate  18  is urged by the spring  29  to cover the hole  65  (shown in  FIG. 7 ). When the hole  65  is covered, because the reset guiding member  37  cannot be pressed down sufficiently along the though hole  62  of the disconnecting member  12  to allow the groove  38  to engage the edge of the hole  61  of the L-shaped lock member  13 , the reset guiding member  37  cannot bring the disconnecting member  12  upwards with it to make the contact between the moveable contact terminals  46 ,  45 ,  47 ,  44  and the stationary contact terminals  50 ,  51 ,  55 ,  56 , respectively. In other words, the reset action cannot be performed. As a result, the input and output sides of the GFCI device cannot be electrically connected. Similarly, if during installation of the GFCI device the output side of the GFCI device is connected to the power lines by mistake (i.e. reverse wiring), such that the hot and neutral wires of the power lines from the wall are connected to terminals  24 ,  25  shown in  FIGS. 8-10 , no voltage is applied to the power supply circuit formed by the diode bridge rectifier circuit D 1 -D 4 . As a result, the plunger  19  in the relay coil  17  is not activated even when the solenoid is in a proper working condition, and the moveable lock plate  18  is urged by the spring  29  and continues to cover the hole  65 . Thus, the reset action cannot be performed, and the input and output sides of the GFCI device cannot be electrically connected. 
     During installation, when the power lines from the wall are correctly connected to the input side GFCI device, i.e., when the line side (LINE) terminals  23 ,  26  are connected to the hot and neutral wires of the power lines, electrical connection between the input and output sides of the GFCI device can be achieved as described below. As shown in  FIGS. 8 ,  4  and  5 , when the solenoid is in a proper working condition and the GFCI device is correctly connected to the power lines, a current flows in the power supply circuit from the hot line (HOT) of the input side (LINE) via the diode bridge rectifier circuit D 1 -D 4  and the solenoid to the neutral line (WHITE) of the input side (LINE). The diode bridge rectifier circuit D 1 -D 4  provides an output voltage, and the relay  17  is energized to generate a magnetic field. The plunger  19  is activated and moves the moveable lock plate  18  to expose the hole  65  under the reset guiding member  37 . At this time, when the reset button  4  is pressed down, the reset guiding member  37  moves downwards in the though hole  62  of the disconnecting member  12 , and the groove  38  on the reset guiding member  37  engages the edge of the hole  61  of the L-shaped lock member  13 . When the reset button  4  is released, the reset guiding member  37  moves upward, bringing disconnecting member  12  upwards with it. The two side arms  53 ,  52  bring the moveable elastic output metal plates  14 ,  15  upwards. As a result, the moveable contact terminals  46 ,  45  come into contact with the stationary contact terminals  50 ,  51  connected to line side (LINE) terminals  23 ,  26 , and the moveable contact terminals  47 ,  44  come into contact with the stationary contact terminals  55 ,  56  on the output conductors  10 ,  11 . The input and output sides of the GFCI device are therefore connected, and power is available at the output side. 
     The GFCI device according to embodiments of the present invention has the following advantages. 
     First, because the moveable elastic output metal plates are used as the output conductor, and the movable contact terminals on the moveable contact arms are used to make electrical contact with the respective stationary contact terminals, the electrical contact is more reliable. Thus, the GFCI device according to embodiments of the present invention has a simple structure and is safe and reliable. 
     Second, the GFCI device according to embodiments of the present invention can prevent power output at the insertion outlets in the event of reverse wiring during installation and when the solenoid SOL is not functioning properly. The GFCI is provided with the relay coil and related components, where the relay coil is electrically connected to the output of the power supply circuit that supplies power to the GFCI control circuit, with the solenoid SOL connected in series in the power supply circuit. When the output side of the GFCI device is connected to the power lines by mistake, or when the solenoid SOL is burnt out (i.e. due to a large current caused by a short in the SCR or other components in the GFCI control circuit), the current path of the power supply circuit is broken, and now voltage is applied to the relay coil. As a result, the relay plunger is not activated, and the moveable lock plate  18  is urged by the spring  29  to cover the hole  65 . The reset button cannot be pressed down to reset the device. Thus, the input side and output side of the GFCI device remain disconnected, preventing power from being output to the insertion outlet on the faceplate of the device. 
     It will be apparent to those skilled in the art that various modification and variations can be made in the GFCI device of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.