Abstract:
The present invention provides a circuit interrupting device which is capable of providing protection against electrical surge through its innovative electrical discharge design; establishing or discontinuing electrical continuity among the input power source, output load, and user accessible load through its innovative contacts connection/disconnection design; automatic or manual testing of the condition of the key components in the circuit interrupting device by way of a simulated leakage current; and testing whether the device is properly wired by way of a reset switch.

Description:
RELATED APPLICATION 
       [0001]    The present application claims the priority of Chinese patent application Nos. 200720178404.5, 200720178405.X, 200720178407.9 and 200720178406.4, all filed on Sep. 30, 2007, the contents of which are herein incorporated by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a circuit interrupting device, preferably a ground fault circuit interrupter, which is capable of providing protection against electrical surge through its innovative electrical discharge design; establishing or discontinuing electrical continuity among the input power source, output load, and user accessible load through its innovative contacts connection/disconnection design; automatic or manual testing of the conditions of the key components in the circuit interrupting device by way of a simulated leakage current; and testing whether the device is properly wired by way of a reset switch. 
       BACKGROUND OF THE INVENTION 
       [0003]    Due to increasingly higher demands for safety of ground fault circuit interrupters (GFCIs), it is desirable to provide safety measures for the GFCIs to allow an end user to find out whether the components of the GFCIs are working properly, whether the GFCIs are properly wired, and whether there is power to the output load. Additionally, it is desirable to extend the life span of the GFCIs by designing a feature that can protect the GFCIs from high voltage surge, such as lightning. The invention described below is designed to encompass the safety functions set forth above. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides four embodiments which can be adopted by a circuit interrupting device either separately or in any combinations to provide various features and functions to the circuit interrupting device. 
         [0005]    The first embodiment of the present invention provides a circuit interrupting device, preferably a ground fault circuit interrupter (GFCI), which has an input end which is electrically connected to an input power source, an output end which is electrically connected to an output terminal, and a user accessible load end which is electrically connected to a user accessible output socket. The circuit interrupting device comprises a pair of input power connecting pieces. Each of the input power connecting pieces is electrically connected to a hot or a neutral wire of the input power source respectively, and the hot wire of the input power source is preferably operationally connected to the neutral wire of the input power source through a solenoid coil and a metal oxide varistor (MOV). 
         [0006]    Also, each of the input power connecting pieces has an end which is extended to a discharge metal piece having a tip. The tip of the discharge metal piece from one input power connecting piece faces, but does not contact with, the tip of the discharge metal piece from the other input power connecting piece. During a high voltage surge, such as lightning, this pair of the discharge metal pieces from the pair of input power connecting pieces causes a discharge of electricity through the tips of the discharge metal pieces to protect the circuit interrupting device from being damaged due to the high voltage surge. The circuit interrupting device further comprises a pair of input flexible metal pieces which is electrically connected to the input power source. Each of the input flexible metal pieces comprises a discharge metal piece which has a tip. The tip of the discharge metal piece from one input flexible metal piece faces but not contacts the tip of the discharge metal piece of the other input flexible metal piece. 
         [0007]    The second embodiment of the present invention provides a circuit interrupting device, preferably a GFCI, which comprises: (1) a pair of output power conductors extended to the user accessible load end; each of the output power conductors comprises a fixed contact and an output conductor flexible metal piece containing a movable contact; (2) a pair of output terminal metal pieces, each comprising a fixed contact; and (3) a pair of input flexible metal pieces electrically connected to the input power source; each of the pair of the input flexible metal pieces contains a movable contact. The movable contact of the output conductor flexible metal piece is capable of connecting/disconnecting to the fixed contact on one of the output terminal metal pieces and each of the input flexible metal pieces is capable of connecting/disconnecting to the fixed contact on one of the output conductors to establish or discontinue the electrically continuity between the input end, the output end, and the user accessible load end. 
         [0008]    The input flexible metal piece of the second embodiment is adapted to operationally pass through a differential transformer. 
         [0009]    The circuit interrupting device further comprises a tripping mechanism located underneath a reset button comprising a reset support piece and a tripping device. The tripping device moves with the reset button when the reset button is depressed or released; the tripping device further extends outward to form a pair of lifting arms; each of the pair of lifting arms has an upper step and a lower step, each having a protrusion which is capable of passing through a through hole on the output conductor flexible metal piece or the input flexible metal piece to be connected to the reset support piece. 
         [0010]    The reset support piece and the tripping device each contains a through hole which is aligned to allow a directional lock from underneath the reset button to pass through. The directional lock is capable of passing through a hole in a locking member when the reset button is depressed and a solenoid coil is energized to reset the circuit interrupting device. It is preferred that the directional lock has a larger diameter in an upper part than in a lower part. Also, the width of the reset support piece is preferred to be shorter than that of the pair of lifting arms extended out from the tripping device. 
         [0011]    The third embodiment of the present invention provides a circuit interrupting device, preferably a GFCI, which comprises a simulated leakage current generating switch (KR- 1 ) coupled to the reset button. When the circuit interrupting device is properly wired and in a tripped state, the simulated leakage current generating switch automatically causes the circuit interrupting device to generate a simulated leakage current which can test components of the circuit interrupting device. 
         [0012]    The simulated leakage current generating switch comprises a first switch piece, a second switch piece, and a third switch piece, which are in triangular arrangement with the first switch piece located at the bottom; the second switch piece situated in the middle; and the third switch piece located at the top. The first switch piece is in series with a resistor and is electrically connected to a neutral line of the input power source. The first switch piece has a contact located at the upper end of the first switch piece. The second switch piece is electrically connected to a hot line of the input power source via a solenoid coil. The second switch piece has two contacts located at the upper and the lower ends of the second switch piece. The third switch piece is electrically connected to the positive pole of a silicon controlled rectifier (SCR), which is then electrically connected to the neutral line of the input power source. The third switch piece has a contact located at a lower end of the third switch piece. The second switch piece is in contact with the first switch piece when the circuit interrupting device is connected to the wall and the reset button is in a tripped state to allow the simulated leakage current to be generated automatically. 
         [0013]    The reset button has a reset support piece located underneath it. A touch pin extends downward from one corner of the reset support piece. When the circuit interrupting device is properly wired and in a tripped state, the springing activity by a quick trip spring, which is slid onto the directional lock, pushes the touch pin of the reset support piece to extend downward and steadily press onto the second switch piece, thus pushing the second switch piece into contact with the first switch piece to allow the simulated leakage current to be generated automatically 
         [0014]    The simulated leakage current ceases to be generated when said circuit interrupting is reset. 
         [0015]    The circuit interrupting device further comprises a test switch (KR- 5 ) coupled to a test button. The test switch comprises a flexible test switch piece and a metal piece in series with a second simulated leakage current generating resistor. When the test button is depressed, the flexible test switch piece is in contact with the metal piece to manually generate the simulated leakage current to test the circuit interrupting device. The flexible test switch piece is electrically connected to a hot wire of the load end and the metal piece is electrically connected to a neutral wire of said input power end. 
         [0016]    The circuit interrupting device further comprises a reset indicator light. When the device is properly wired and in a tripped state, if the components of the circuit interrupting device work properly, the reset indicator light lights up. 
         [0017]    Additionally, the circuit interrupting device comprises a power output indicator light. When the circuit interrupting device has power to the output end and the user accessible load end, the power output indicator light is lit. 
         [0018]    The components of the circuit interrupting device that can be tested by the simulated leakage current comprises solenoid coil and silicon controlled rectifier (SCR). Additionally, the differential transformer and the leakage current detection integrated chip can also be tested. 
         [0019]    The final embodiment of the present invention provides a circuit interrupting device which comprises a reset switch (KR- 4 ) coupled to a reset button. The reset switch comprises a flexible metal switch piece and an electric contact. When the circuit interrupting device is properly wired and in a stripped state, a depression of the reset button allows the flexible metal switch piece to be in contact with the electric contact to allow reset. 
         [0020]    One end of the flexible metal switch piece is electrically connected to a hot wire of the input power end through a solenoid coil and the other end is suspended. The electric contact is electrically connected to the positive pole of a silicon controlled rectifier (SCR), which is then electrically connected to a neutral wire of the input power end. When the reset button is depressed, the flexible metal switch piece is in contact with the electric contact. 
         [0021]    Alternatively, one end of the flexible metal switch piece is electrically connected to a neutral wire of the input power end through a solenoid coil and the other end is suspended. The electric contact is electrically connected to a hot wire of the input power end through the positive pole of a silicon controlled rectifier (SCR). When the reset button is depressed, the flexible metal switch piece is in contact with said electric contact. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is an exploded cubic schematic of the structure of the present invention. 
           [0023]      FIG. 2  is the main view of the present invention. 
           [0024]      FIG. 3  is the front view of the present invention with the upper lid removed. 
           [0025]      FIG. 4  is an illustration of the relationships among the input flexible metal pieces, output conductors, output conductor flexible metal pieces, and output terminal metal pieces of the present invention and their structures. 
           [0026]      FIG. 5  is an illustration of the relationships among the parts which can be viewed on top of the printed circuit board of the present invention. 
           [0027]      FIG. 6  is an exploded cubic schematic of the structure of the model reset/tripping mechanical construction of the present invention. 
           [0028]      FIG. 7-1  is a partial cross-sectional view along the B-B line in  FIG. 3 . It is an illustration of the relationships among the parts how the GFCI works initially when there is no power output. 
           [0029]      FIG. 7-2  is a partial cross-sectional view along the B-B line in  FIG. 3 . It is an illustration of the relationships among the parts when the reset button is depressed. 
           [0030]      FIG. 7-3  is a partial cross-sectional view along the B-B line in  FIG. 3 . It is an illustration of the relationships among the parts after the device has been reset and the GFCI works normally and has power output. 
           [0031]      FIG. 7-4  is a partial cross-sectional view along the B-B line in  FIG. 3 . It is an illustration of the relationships among the parts when the test button is depressed to cut off power output to the load and user accessible load of the GFCI. 
           [0032]      FIG. 8-1  is a partial cross-sectional view along the C-C line in  FIG. 3 . It is an illustration of the relationships among the parts after the reset button is depressed and the interrupter has power output. 
           [0033]      FIG. 8-2  is a partial cross-sectional view along the C-C line in  FIG. 3 . It is an illustration of the relationships among the parts when the device is tripped and the GFCI has no power output. 
           [0034]      FIG. 9-1  is a partial cross-sectional view along the A-A line in  FIG. 3 . It is an illustration of the relationships among the parts when the device is in a tripped state. 
           [0035]      FIG. 9-2  is a partial cross-sectional view along the A-A line in  FIG. 3 . It is an illustration of the relationships among the parts the instant the reset button is pressed. 
           [0036]      FIG. 9-3  is a partial cross-sectional view along the A-A line in  FIG. 3 . It is an illustration of the relationships among the parts after the device has been reset. 
           [0037]      FIG. 10  is a detailed circuitry on the control circuit board of the GFCI of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0038]    As shown in  FIG. 1 , the GFCI disclosed by the present invention mainly comprises a housing, and a circuit board  18  which is installed inside the housing. 
         [0039]    Within the housing, there are upper cover  2 , insulated middle support  3  and base  4 . Between upper cover  2  and insulated middle support  3 , there is metal mounting strap  1 . Circuit board  18  is installed between insulated middle support  3  and base  4 . 
         [0040]    As shown in  FIG. 1  and  FIG. 2 , upper cover  2  contains power output sockets  5  and  6 , reset button hole  8 -A, test button hole  7 -A and status indicator hole  30 -A. Reset button (RESET)  8  and test button (TEST)  7  are placed inside reset button hole  8 -A and test button hole  7 -A, respectively. Reset button  8  and test button  7  pass through metal strap  1  and insulated middle support  3 , and come into contact with the component assembly on circuit board  18 . There are four clamp hooks  2 -A on both sides of upper cover  2  which are used to securely connect base  4  through fasten groove  4 -B located on the inner side of base  4 . 
         [0041]    Metal mounting strap  1  is located between upper cover  2  and insulated middle support  3 , and is connected to the ground through ground screw  13 -A. Grounding vanes  11  and  12  are located on metal mounting strap  1 , at locations vertically corresponding to the grounding holes on power output sockets  5  and  6  of upper cover  2 . Installation holes  13 -B are placed on both ends of metal mounting strap  1 . 
         [0042]    As shown in  FIG. 1  and  FIG. 3 , a hot power line output conductor  14  and a neutral power line output conductor  13  are respectively placed on both sides of insulated middle support  3  within the housing and extended to contain gripping wing pieces  60 ,  61 ,  62  and  63 . Gripping wing pieces  60 ,  61 ,  62  and  63  are located directly under the neutral power line holes and hot power line holes of power output sockets  5  and  6  of upper cover  2 . As shown in  FIG. 3  and  FIG. 4 , on one end of hot power line output conductor  14 , there is a fixed contact  16 . On the other end of hot power line output conductor  14 , there is an output conductor flexible metal piece  21  which is connected to the output conductor  14  by a rivet. A movable contact  23  is attached to the end of output conductor flexible metal piece  21 . Similarly, at one end of neutral power line output conductor  13 , there is a fixed contact  15 . On the other end of neutral power line output conductor  13 , there is an output conductor flexible metal piece  20  which is connected to the output conductor  13  by a rivet. A movable contact  22  is attached to the end of output conductor flexible metal piece  21 . 
         [0043]    As shown in  FIG. 1 , base  4  is used to accommodate insulated middle support  3  and control circuit board  18 . On the two sides of base  4 , a pair of neutral power line and hot power line input wiring screws  9  and  10  and a pair of neutral power line and hot power line output wiring screws  109  and  110  are symmetrically placed. 
         [0044]    The core component of the present invention is control circuit board  18  which is installed within the housing. It has the functions of causing power outlet sockets  5  and  6  on upper cover  2  of the GFCI and power output wiring screw  109  and  110  located on both sides of base  4  to have or not to have power output; testing the components of the GFCI to determine whether these components have come to an end of their service life; displaying the test result by indicator lights on upper cover  2  and causing the reset button to reset or to trip; protecting the device against high voltage surge such as lightning; and preventing any reverse wiring error occurred during the installation of the GFCI. 
         [0045]    As shown in  FIG. 1  and  FIG. 5 , on circuit board  18 , there are a pair of hot power line and neutral power line input flexible metal pieces  51  and  50 . One end of power input flexible metal pieces  51  and  50  is bent 90 degrees downward to facilitate power input flexible metal pieces  51  and  50  to pass through differential transformer  19 . Alternatively, power input flexible metal pieces  51  and  50  can be fastened to separate pieces which in turn pass through differential transformer  19 . The power input flexible metal pieces  51  and  50  can either weld onto circuit board  18  or directly connect to hot power line, neutral power line input wiring screws  10  and  9  through input power connecting pieces  25  and  24 . Hot power line input wiring screw  10  is connected to a hot power line inside the wall through a wire. Neutral power line input wiring screw  9  is connected to a neutral power line inside the wall through a wire. Movable contacts  55  and  54  are placed on the other end of input flexible metal pieces  51  and  50 . 
         [0046]    Hot and neutral power output terminal metal pieces  81  and  80  are welded onto the other end of circuit board  18  and come into contact with power output wiring screws  110  and  109 . Hot and neutral power output terminal metal pieces  81  and  80  contain fixed contacts  53  and  52  respectively which are protruded sideward from the metal pieces. 
         [0047]    As shown in  FIG. 3 ,  FIG. 4  and  FIG. 5 , movable contacts  54  and  55  on power input flexible metal pieces  51  and  50  respectively come into contact with or disconnect from a pair of fixed contacts  16  and  15  on output conductors  14  and  13  above insulated middle support  3 , forming a group of hot line and neutral line power switches. Movable contacts  23  and  22  on the pair of output conductor flexible metal pieces  21  and  20  come into contact with or disconnect from fixed contacts  53  and  52  on power output terminal metal pieces  81  and  80 , forming another group of hot line and neutral line power switches. The movable and fixed contacts on power input flexible metal pieces  51  and  50 , power output conductors  14  and  13 , output conductor flexible metal pieces  21  and  20  as well as on power output terminal metal pieces  81  and  80  form a total of two groups of hot line and neutral line power switches  55  and  16 ,  54  and  15 ,  23  and  53 , and  22  and  52 , which respectively correspond to switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  in wiring diagram in  FIG. 10 . 
         [0048]    As shown in  FIG. 1 ,  FIG. 5  and  FIG. 7-1 , there is also a differential transformer  19  on circuit board  18  which is used for detecting leakage currents. As shown in  FIG. 10 , the hot power line HOT and neutral power line WHITE pass through differential transformer  19  (L 1  and L 2  in the figure). When there is a leakage current (i.e., an imbalance current between the hot and white lines) on the power supply loop, the differential transformer will output a voltage signal to the leakage current detection control chip IC (model No. RV4145). Pin  5  of the chip IC outputs a control signal to silicon controlled rectifier (SCR), causing the reset/tripping mechanical device on circuit board  18  to act, so that reset button  8  pops up and the GFCI trips, cutting off the power output from the GFCI. 
         [0049]    As shown in  FIG. 1 ,  FIG. 5 ,  FIG. 6 ,  FIG. 7-1  and  FIG. 9-1 , a reset/tripping mechanical device is also placed on circuit board  18  which causes input flexible metal pieces  50  and  51  to be electrically connected to or disconnected from output conductors  13  and  14 , and causes output conductor flexible metal pieces  20  and  21  to be electrically connected to or disconnected from power output terminal metal pieces  80  and  81 . The reset/tripping mechanical device includes a directional lock  35  which is embedded underneath reset button  8 ; reset spring  91  and quick trip spring  66 -A which are slid onto directional lock  35 ; a reset support piece  28 A; a “T” shaped tripping device  28  coupled to reset button  8 ; locking member  30 ; locking member spring  34 ; simulated leakage current generating switches  66 ,  67  and  88  which are coupled to reset button  8 ; reset switches  72  and  72 A and solenoid coil  26 . 
         [0050]    The reset support piece  28 A is made of plastic and is located below and coupled to reset button  8 . The left and right sides of the “T” shaped tripping device  28  extend outward to form a pair of stepped lifting arms. In an embodiment of the present invention, the left and right lifting arms  27 A and  28 B are shaped like two steps. A small protruding cylinder  28 F is placed on each step. Reset support piece  28 A is located below reset button  8  and above the “T” shaped tripping device  28 . To facilitate assembly, the length of reset support piece  28 A is preferred to be shorter than the span of the lifting arms from the tip of the left to the tip of the right sides of tripping device  28 . Recessed round holes are placed on the bottom surface of reset support piece  28 A in places that receive protruding cylinders  28 F on the left and right lifting arms of tripping device  28  to connect reset support piece  28 A to tripping device  28  so that both pieces can move up and down with reset button  8 . At the same time, reset support piece  28 A can also be detached from tripping device  28 . In solenoid framework  26 K of solenoid coil  26  which accommodates reset support piece  28 A and tripping device  28 , there is a limiting block  26 Z which limits the lowest possible movement of reset support piece  28 A. 
         [0051]    As shown in  FIG. 5 , through holes  69  are placed on input flexible metal pieces  51  and  50  and output conductor flexible metal pieces  21  and  20  at places corresponding to the vertical passing lines of protruding cylinders  28 F on the left and right lifting arms of tripping device  28  to allow protruding cylinders  28 F to pass through in order to be received by reset support piece  28 A. As shown in  FIG. 9-1 , when tripping device  28  and reset support piece  28 A are assembled, the protruding cylinders  28 F on the left and right lifting arms of tripping device  28  are first passed through through-holes  69  on input flexible metal pieces  51  and  50  and output conductor flexible metal pieces  21  and  20 , thus placing output conductor flexible metal pieces  21  and  20  above steps  28 B on the outer side of the left and right lifting arms of tripping device  28  and placing input flexible metal pieces  51  and  50  above steps  27 A on the inner side of the left and right lifting arms of tripping device  28  and below reset support piece  28 A. Then, the protruding cylinders  28 F are slide into the recessed round holes on the bottom surface of reset support piece  28 A. At the same time when tripping device  28  coupled to reset button  8  move up and down, input flexible metal pieces  51  and  50  and output conductor flexible metal pieces  21  and  20  are also driven by the movement of reset button  8  to move up and down. 
         [0052]    In the middle of the reset support piece  28 A, there is a vertical through hole  29 A that allows directional lock  35  to be threaded through. In the middle of tripping device  28 , there is also a vertical through hole  29  to allow directional lock  35  to thread through. As shown in  FIG. 7-1  and  FIG. 9-1 , directional lock  35 , which is embedded underneath reset button  8  and onto which reset spring  91  and quick trip spring  66 -A are slid, can move up and down along the straight through hole  29 A and central through hole  29  in the middle sections of reset support piece  28 A and tripping device  28 . The diameter of the upper part of the directional lock  35  is larger than the diameter of the lower part. Step  35 A is formed between the upper and lower parts of directional lock  35 ; reset spring  91  slides onto the upper part of directional lock  35  and is located between reset button  8  and insulated middle support  3 ; quick trip spring  66 -A slides onto the lower part of directional lock  35  and is located between step  35 A of directional lock  35  and reset support piece  28 A. When the reset button is at a tripped state, reset support piece  28 A is combined with tripping device  28  due to pushed pressure from quick trip spring  66 -A. 
         [0053]    A circular groove  36  is located near the bottom of directional lock  35 . The bottom of directional lock  35  is a blunt plane  41 . When reset button  8  is at a tripped state, blunt plane  41  of directional lock  35  and a through hole  31  in locking member  30  are in a staggered position so that directional lock  35  cannot pass through locking member  30 . 
         [0054]    Tripping device  28  has a through hole  30 E in the middle section. Locking member  30  is a movable “L” shaped latch, preferably made of metal materials. It is inserted across the middle section of tripping device  28  by through hole  30 E. When reset button  8  is in a tripped state, blunt plane  41  of directional lock  35  is above locking member  30  and is in a staggered state with locking member hole  31  on top of locking member  30 . 
         [0055]    A locking member spring  34  is placed between the side wall of tripping device  28  and the inside wall of locking member  28 . A solenoid coil  26  with a built-in movable iron core  42  is placed on the outside wall of locking member  30 . Built-in movable iron core  42  of solenoid coil  26  directly faces the side wall of locking member  30 . When solenoid coil  26  is energized, the iron core moves inward and plunges upon the outside wall of locking member  30  to force locking member  30  to move horizontally, thus enabling blunt plane  41  of directional lock  35  below reset button  8  to be aligned with through hole  31  and move downward to facilitate reset of the device or move upward to facilitate tripping of the device. Movable iron core  42  has a tower shaped spring  42 A slid at the end portion of the iron core  42 . 
         [0056]    As shown in  FIG. 6  and  FIG. 9-1 , a simulated leakage current generating switch (switch KR- 1  in  FIG. 10 ) is coupled to reset button (RESET)  8  and is placed beside tripping device  28 . The simulated leakage current generating switch comprises three triangularly arranged metal switch pieces  66 ,  67  and  88 . The first metal switch piece  66  is located at the bottom; the second flexible metal switch piece  88  is located in the middle; and the third metal switch piece  67  is at the top. On the upper surface of first metal switch piece  66 , a contact  68 C is placed. On the upper and lower surfaces of second flexible metal switch piece  88 , contacts  68 A and  68 B are respectively placed. On the lower surface of third metal switch piece  67 , a contact  67 A is placed. Reset support piece  28 A extends a touch pin  28 E downward which is capable of pressing down on the second flexible metal switch piece  88 . When the GFCI is properly wired and is at a tripped state, automatically due to the compression of quick trip spring  66 -A, touch pin  28 E of reset support piece  28 A extends downward to cause contact  68 B on the lower surface of the second flexible metal switch piece  88  to be in contact with contact  68 C on the upper surface of first metal switch piece  66 . As shown in  FIG. 9-2 , when reset button  8  is depressed, contact  68 B on the lower surface of the second flexible metal switch piece  88  remains in contact with contact  68 C on the upper surface of the first metal switch piece  66 . As shown in  FIG. 9-3 , when the device is reset, both reset button  8  and tripping device  28  move up, driving reset support piece  28 A to move up together with them and causing touch pin  28 E to concurrently move away from the upper surface of the second flexible metal switch piece  88 . Under its own flexible action, the second flexible metal switch piece  88  causes contact  68 B on its lower surface to be disconnected from contact  68 C on the upper surface of the first metal switch piece  66 . Contact  68 A on the upper surface of the second flexible metal switch piece  88  comes into contact with contact  67 A on the lower surface of the third metal switch piece  67  and become conducted. As shown in  FIG. 10 , first metal switch piece  66  is at the bottom and is connected to the neutral line via differential transformer  19  and through simulated leakage current limiting resistor R 4 ; second flexible metal piece  88  is in the middle and is connected to the hot line AC current via solenoid coil  26  (L 3  in  FIG. 10 ); third metal piece  67  is connected to the neutral line on the power input end through silicon controlled rectifier (SCR) V 4 . Therefore, when the GFCI is properly wired and is at a tripped state, the combined actions of quick trip spring  66 -A and touch pin  28 E of reset support piece  28 A allows contact  68 B on the lower surface of second flexible metal switch piece  88  to be in contact with contact  68 C on the upper surface of first metal piece  66  to activate resistor R 4  to automatically generate a simulated leakage current, thus achieving the purpose of, without the need to operate any part, testing the functionality of differential transformers L 1  and L 2 , solenoid coil  26  (L 3 ), the leakage current detection chip IC, and the SCR. The hot power line is connected to the neutral power line which threads through differential transformer L 1  and L 2  through solenoid coil  26  (L 3 ), flexible metal piece  88 , metal piece  66  and resistor R 4 , forming a simulated leakage current generating loop and automatically generating a simulated leakage current, to detect whether the GFCI has come to the end of its service life. If the GFCI has not come to the end of its service life, a reset indicator light V 5  is lit. If the GFCI has come to the end of its service life, the GFCI prevents the reset button from being reset and the end-of-life reset indicator V 5  is not lit. After reset button  8  is reset, the second flexible metal piece  88  is disconnected from the first metal piece  66 , and comes into contact with third metal piece  67 . The simulated leakage current that has been generated through the connection with first metal piece  66  disappears naturally. 
         [0057]    In sum, when contact  68 B on the lower surface of the second flexible metal piece  88  comes into contact with contact  68 C on the upper surface of the first metal piece  66 , a simulated leakage current is automatically generated. The GFCI is in an end-of-life testing state. When contact  68 A on the upper surface of flexible metal piece  88  comes into contact with contact  67 A on the lower surface of metal piece  67 , the simulated leakage current disappears and the GFCI is in a reset state. 
         [0058]    As shown in  FIG. 6  and  FIG. 7-1 , a reset switch (KR- 4  in  FIG. 10 ) is coupled to reset button  8  and is placed below tripping device  28 . The reset switch comprises flexible metal piece  72  and electric contact  72 A. One end of flexible metal piece  72  is welded onto the circuit board and is connected to hot line on the power input end through solenoid coil  26  (L 3  in  FIG. 10 ); the other end is suspended in the air and above electric contact  72 A. A contact  72 C is on flexible metal piece  72  and is at a place directly above electric contact  72 A. Electric contact  72 A is welded onto the circuit board  18  and is connected to the positive pole of SCR V 4 . When reset button  8  is at a tripped state as shown in  FIG. 7-1  and when reset button  8  is in a reset state as shown in  FIG. 7-3 , flexible metal piece  72  and contact  72 A do not contact with each other. The reset switch is in a nonconductive state. When reset button  8  is pressed down, as shown in  FIG. 7-2 , tripping device  28  presses down on flexible metal piece  72 , causing contact  72 C of flexible metal piece  72  and contact  72 A to come into contact and become conducted. The reset switch KR- 4  is closed. When reset button  8  is released, as shown in  FIG. 7-4 , flexible metal piece  72  and contact  72 A are disconnected, thus reflecting the condition of reset button  8 . 
         [0059]    As shown in  FIG. 6 , reset support piece  28 A, tripping device  28 , locking member  30 , locking member spring  34 , reset button  8 , simulated leakage current generating switch  66 ,  67  and  88  coupled to reset button  8  as well as reset switch  72  and  72 A are all shielded within solenoid framework  26 K of the solenoid coil  26 . There is a solenoid coil protection shield  41 -C outside the coil of solenoid coil  26 , on whose top surface there are four rectangular holes  80 A and  81 A; on its left and right sides, there is respectively a hooked pin  41 -B which is used to hook onto circuit board  18 . On the side of solenoid coil protection shield  41 -C, there is a step  41 -F which is used to support output conductor flexible metal pieces  21  and  20 . At the place where the top surface and side of solenoid coil protection shield  41 -C meet, there is a step  41 -H which is used to support input flexible metal pieces  51  and  50 , so as to reduce pressure from output conductor flexible metal pieces  21  and  20  and input flexible metal pieces  51  and  50  on the lifting arms on the left and right sides of tripping device  28 . This would allow output conductor flexible metal pieces  21  and  20  and input flexible metal pieces  51  and  50  to work steadily. 
         [0060]    Directional lock  35  that forms the reset/tripping mechanical device, reset spring  91  and quick trip spring  66 -A that slide onto directional lock  35 , reset support piece  28 A, the “T” shaped tripping device  28  that is coupled to reset button  8 , locking member  30 , locking member spring  34 , the simulated leakage current generating switch  66 ,  67  and  88  that is coupled to reset button  8 , the reset switch  72  and  72 A, and solenoid coil  26  are interconnected to form a freely movable body and support each other. 
         [0061]    As shown in  FIG. 7-1  and  FIG. 3 , below test button  7  there are flexible metal piece  46  and metal piece  47  which contains a simulated leakage current generating resistor R 3 . A pressing of test button  7  cause flexible metal piece  46  to be in contact with metal piece  47  which manually generates a simulated leakage current. The flexible metal piece  46  and the metal piece  47  (resistor R 3  in  FIG. 10 ) form test switch (KR- 5 ) in  FIG. 10 . One end of flexible metal piece  46  is connected to the hot line of the power output end LOAD of the ground fault circuit interrupter, while the other end is suspended in the air and below it, there is the metal piece  47  which contains the simulated leakage current generating resistor R 3 ; one end of the metal piece  47  is suspended below flexible metal piece  46 , while the other end is connected to the neutral line at the power input end. As shown in  FIG. 7-4 , when test button  7  is depressed, flexible metal piece  46  comes into contact with metal piece  47  and manually generates a simulated leakage current. When test button  7  is released, flexible metal piece  46  is disconnected from the metal piece  47  and the simulated leakage current disappears. 
         [0062]      FIG. 10  is the circuit diagram of the GFCI. As shown in the diagram, the control circuit mainly comprises differential transformers L 1  (1000:1) and L 2  (200:1) used for detecting an electric leakage current, control chip IC (RV4145), solenoid coil L 3  (SOL) with a built in iron core, silicon controlled rectifier (SCR) V 4 , simulated leakage current generating switch KR- 1  coupled to reset button RESET, switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  serially connected in the power supply line, reset switch KR- 4  coupled to reset button RESET, reset indicator light V 5 , power output indicator light V 3 , simulated leakage current generating resistors R 4  and R 3  and some related diodes, resistor and capacitances, etc. 
         [0063]    After the hot power line HOT and neutral power line WHITE on the power input line for the GFCI pass through differential transformers L 1  and L 2 , they are connected to the hot line and neutral line output conducting socket in the plug hole of the single phase, three line socket on the surface of the GFCI through switches KR- 2 - 1  and KR- 2 - 2 . At the same time, the hot line HOT, neutral line WHITE output conducting socket in the plug hole of the single phase, three line socket on the surface of the GFCI is connected to hot line HOT, neutral line WHITE of the output end (load connecting end) LOAD of the GFCI through another group of switches KR- 3 - 1  and KR- 3 - 2 . Switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1 , and KR- 3 - 2  are capable of moving up and down with the reset button RESET. 
         [0064]    The leakage current detection signal output ends of differential transformers L 1  and L 2  are connected to signal input pins  1 ,  2 ,  3  and  7  of the control chip IC. Control signal output pin  5  of the control chip IC is connected to the gate of silicon controlled rectifier (SCR) V 4 . Power input pin  6  of control chip IC is connected to hot line HOT on the power input end LINE of the GFCI through diode V 1 , resistor R 1  and solenoid coil L 3 . Ground pin  4  of control chip IC is connected to neutral line WHITE on the power input end LINE of the GFCI. 
         [0065]    The negative pole of silicon controlled rectifier (SCR) V 4  is connected to neutral line WHITE on the power input end LINE of the GFCI. The positive pole of silicon controlled rectifier (SCR) V 4  is connected to the hot line HOT on the power input end through reset switch KR- 4  and solenoid coil  26  coupled to reset button RESET. At the same time, the positive pole of silicon controlled rectifier (SCR) V 4  is also connected to first metal switch piece  67  of the simulated leakage current generating switch KR- 1 . 
         [0066]    Simulated leakage current generating switch KR- 1  is a switch with a pair of constantly closed contacts and a pair of constantly open contact. The KR- 1  contains a sharing point A, i.e., via the second flexible metal piece  88 , which is connected to the hot line HOT on the power input end of the GFCI through solenoid coil L 3 . KR- 1 &#39;s constantly closed contact, i.e., metal piece  66 , is connected to power neutral line WHITE that passes through differential transformers L 1  and L 2  through simulated leakage current generating resistor R 4 . KR- 1 &#39;s constantly open contact, i.e., metal piece  67 , is connected to the positive pole of silicon controlled rectifier (SCR) V 4 . 
         [0067]    The iron core built-in solenoid coil L 3  causes reset button RESET to reset or trip through the reset/tripping mechanical device inside the GFCI, thus causing switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  to move with reset button RESET so as to establish or discontinue electric continuity among the input end, the output load end, and the user accessible load end. The iron core built-in solenoid coil L 3  further causes the simulated leakage current generating switch KR- 1  to disconnect or close. 
         [0068]    A power output indicator light V 3  (LED 1 ) is connected between power output end LOAD of the hot line and the neutral line of the GFCI. It is used to indicate whether the GFCI has power output. When the GFCI has power output, LED 1  is lit; otherwise, LED 1  is not lit. 
         [0069]    Between positive pole B of silicon controlled rectifier (SCR) V 4  and sharing point A of simulated leakage current generating switch KR- 1  is a reset indicator light V 5  (LED 2 ), which is used to indicate whether the GFCI has come to the end of its service life. When the leakage current protection circuit works normally, i.e., components comprising the leakage current protection circuit, such as silicon controlled rectifier V 4 , solenoid coil  3 , differential transformers L 1  and L 2  and control chip IC are intact and cable of being conducted normally, the reset indicator light LED 2  is lit, indicating that the GFCI has leakage current protection functions. Otherwise, when one of the components of the leakage current protection circuit fails, the end-of-life reset indicator LED 2  is not lit, indicating that the leakage current protection circuit has come to the end of its life and reminding the user to get a good replacement the GFCI in a timely manner. 
         [0070]    As shown in  FIG. 9-1 , the power output indicator light and the reset indicator light are side-by-side placed on control circuit board  18 . A vertically placed light guide tube  77  is placed above the two indicator lights. The light guide tube  77  passes through hole D on insulated middle support  3  (as shown in  FIG. 3 ), and its tip is located below indicator hole  30 -A on the surface of upper cover  2 . 
         [0071]    An automatic simulated leakage current is formed when the neutral line WHITE of the power input end which threads through different transformers L 1  and L 2  is connected to the hot line HOT of the power input end through simulated leakage current generating resistor R 4 , the constantly closed contact of simulated leakage current switch KR- 1  (i.e., metal piece  66 ), and solenoid coil L 3  (SOL). After the power input end LINE of the GFCI is properly connected to the power line inside the wall and the device is in a tripped state, since the constantly closed contact of simulated leakage current switch KR- 1  coupled to reset button RESET is in a closed state a simulated leakage current is generated. When the leakage current protection circuit works normally, after the leakage current is detected, the constantly closed contact of simulated leakage current generating switch KR- 1  is disconnected through the reset/tripping mechanical device, and the constantly open contact closes, and therefore the simulated leakage current disappears and reset button RESET is reset. 
         [0072]    As shown in  FIG. 10 , after the GFCI is properly wired to the wall and the reset button has not been reset and the pair of constantly closed contacts of simulated current generating switch KR- 1  connects hot line HOT on the power input end to power neutral line WHITE that passes through differential transformers L 1  and L 2 , the simulated leakage current generating circuit automatically generates a simulated leakage current. The leakage current flows through differential transformers L 1  and L 2  which outputs a signal to the control chip IC. Pin  5  of the control chip IC outputs a high potential control signal to the gate of silicon controlled rectifier (SCR) V 4  to trigger SCR. The positive pole and the negative pole of the SCR are conducting. A large current flows through solenoid coil L 3 . Solenoid coil L 3  generates a magnetic field to move its iron core into the solenoid coil and causes reset button RESET to act through the reset/tripping mechanical device. The reset button is reset, while at the same time, the constantly open contact of simulated current generating switch KR- 1  is closed; the constantly closed contact is disconnected and the simulated leakage current disappears. 
         [0073]    By contrast, if the leakage current protection circuit is not working properly and the GFCI has come to the end of its service life, then SCR V 4  is not conducting so that no large current will flow through solenoid coil L 3 . As a result, no magnetic field is generated, and the built-in iron core within the solenoid coil does not act, so that the reset/tripping mechanical device does not act and the reset button cannot be reset. The reset indicator light V 5  and the power output indicator light V 3  are not lit, thus reminding the user that the GFCI has come to the end of its life and a good replacement the ground fault circuit interrupter is required. 
         [0074]    As shown in  FIG. 10 ,  FIG. 7-2  and  FIG. 9-2 , when reset button RESET is depressed and when constantly closed contacts  68 C and  68 B of simulated leakage current generating switch KR- 1  are not yet disconnected, but the reset switch KR- 4  which is coupled to reset button RESET is closed. At this time, since the closure of KR- 4  causes point A and point B to have a short connection, the original voltage on point A and point B is applied to solenoid coil (SOL) L 3 , causing a certain current to flow through the solenoid coil to generate a magnetic field. The iron core inside the solenoid coil is engaged in an impact movement. Through the reset/tripping mechanical device, the reset button can be reset, as shown in  FIG. 7-3  and  FIG. 8-1 . Light emitting diode V 5  connected between point A and point B is in a cut off state and indicator light V 5  goes out. At the same time, due to the action of reset button RESET, constantly closed contacts  68 B and  68 C of the simulated leakage current switch KR- 1  coupled thereto are disconnected. Constantly open contact  67 A and  68 A are closed, and the simulated leakage current disappears. After reset button RESET is reset, switch KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  coupled thereto are closed, the GFCI has power output and power output indicator light V 3  is lit, indicating that both the single phase, three line socket on the surface of the interrupter and LOAD output end have power output. 
         [0075]    When the functions of the GFCI are intact, after the GFCI is powered and the reset button RESET is depressed, load end LOAD and the user accessible load end of the GFCI have power output and the GFCI works normally. At this time, if a leakage current is detected, due to the fact that hot power line HOT and neutral line WHITE both pass through the differential transformers L 1  (1000:1) and L 2  (200:1), because the currents from the two power lines, respectively, that passes through differential transformers L 1  and L 2  are not the same, differential transformers L 1  and L 2  immediately sent a voltage signal with a certain value to the control IC. A control signal is output from pin  5  of the IC to the gate of SCR V 4 . SCR V 4  is triggered and the positive pole and the negative pole become conducted, thus causing point B on the positive pole of SCR V 4  to be at a low electric potential. Because the constantly open contact of switch KR- 1  is in a closed state, point A and point B are the same point. Since the other end of solenoid coil L 3  is connected to the hot power line, both ends of solenoid coil L 3  will receive a voltage of a certain value. A certain amount of electric current flows through the solenoid coil L 3  and generates a magnetic field. The iron core within the solenoid coil is engaged in plunged onto the side wall of the locking member  30 , causing reset button RESET to be tripped through the reset/tripping mechanical device and power output to be cut off. As shown in  FIG. 8-2 , power output indicator light V 3  goes out and the reset indicator light V 5  is lit. 
         [0076]    When a test needs to be performed to determine whether the GFCI functions normally, as shown in  FIG. 7-4 , test button TEST  7  can be pressed, to cause test switch KR- 5  coupled to the test button  7  to be closed, thus generating a simulated leakage current to test the components of the GFCI. If the leakage current protection circuit does not work normally and the GFCI has come to the end of its life, the reset indicator light V 5  is not lit and reset button RESET cannot be reset. 
         [0077]    In the situation as shown above, the control signal output from pin  5  of the IC must pass through and be connected to anti-jamming capacitance C 5  between the gate of the SCR and ground to prevent the occurrence of triggering by error. 
         [0078]    To improve the life of the ground fault circuit interrupter and avoid any damage to the GFCI caused by instantaneous high voltage such as lightning or as a result of any other cause, as shown in  FIG. 10  and  FIG. 5 , the present invention provides discharge metal pieces  25 A and  24 A which are extended from the ends of the power input connecting pieces  25  and  24  that connect the GFCI with hot power line and neutral power line input wiring screws  10  and  9 . The tips of the two metal pieces are placed opposite to each other and keep a certain distance from each other. 
         [0079]    As shown in  FIG. 10 ,  FIG. 5 ,  FIG. 7-1  and  FIG. 8-1 , the discharge metal pieces  51 A and  50 A can also be found on input flexible metal pieces  51  and  50  that pass through the differential transformers. The tips of the two discharge metal pieces are placed opposite to each other and keep a certain distance from each other. 
         [0080]    In addition, hot line HOT of the power input end passes through solenoid coil SOL and a metal oxide varistor MOV to be connected to neutral line WHITE on the power input end. 
         [0081]    When an instantaneous high voltage caused by lightning or any other cause acts on the ground fault circuit interrupter, the air media between the tips of the discharge metal pieces  25 A and  51 A, which are connected to the input end hot line, and the tips of discharge metal piece  24 A and  50 A, which are connected to the neutral line on the input end, is broken down, causing the air to discharge. Most of the high voltage is consumed through the discharging metal pieces, and the small remaining part is consumed through solenoid coil SOL and the metal oxide varistor MOV, thus protecting the ground fault circuit interrupter from being damaged by high voltage. 
         [0082]    If the metal oxide varistor MOV used in the GFCI is a surge suppressing MOV, it has the capability of preventing electrophoresis. 
         [0083]    As shown in  FIG. 10 , the GFCI of the present invention is also capable of preventing reverse wiring errors. As shown in  FIG. 10 , the load output end LOAD of the GFCI is connected to the single phase, three line output socket on the surface of the GFCI through switches KR- 3 - 1  and KR- 3 - 2  coupled to reset button RESET; hot line and neutral line on the input end the GFCI is connected to the hot line and neutral line of the single phase, three line output socket on the surface of the GFCI through switches KR- 2 - 1  and KR- 2 - 2 . Therefore, when an installer erroneously connects the power line inside a wall to the load output end LOAD of a GFCI, the present invention will automatically prevent reset because no simulated leakage current can be generated through the simulated leakage current generation circuit (comprising the constantly closed contacts of simulated leakage current switch KR- 1 , resistor R 4  and solenoid coil SOL). Control chip IC cannot output any control signal. SCR V 5  is not conducted. No current flows through solenoid coil SOL, thus no magnetic field is generated to push the built-in iron core to act. The reset/tripping mechanical device does not act, thus automatically preventing the reset button from being reset. Because switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  are coupled to reset button RESET, the non-movement of the reset button causes switches KR- 2 - 1 , KR- 2 - 2 , KR- 3 - 1  and KR- 3 - 2  to stay opened. Neither the input end LINE nor the power socket on the surface of the GFCI has power output. Reset indicator light V 5  is not lit, indicating a wiring error. It is only after the installer properly connects the wire then reset indicator light V 5  can be lit, reset button can be reset and the GFCI has power output. 
         [0084]    In conclusion, the GFCI disclosed in the present invention has the following outstanding advantages: 
         [0085]    (1) The GFCI has superior testing capability: After the power input end of the GFCI is properly connected to the power line within the wall, without operating of any part, a simulated leakage current can be automatically generated to detect whether the GFCI has protective functions against the leakage current, i.e., whether or not it has come to the end of its life by displaying the test result. 
         [0086]    a. When the components of the GFCI are working properly and the leakage current protection circuit has not come to the end of its life, the reset indicator light V 5  is lit, indicating that a correct reset mechanism can be set up so that the reset button can be reset. After the reset, power output indicator light V 3  is lit and reset indicator light V 5  goes out, indicating that the GFCI can work normally; 
         [0087]    b. When one or more of the components in the leakage current protection circuit are no longer functioning, reset indicator light V 5  is not lit, indicating that the leakage current protection circuit has come to the end of its life and the reset button cannot be reset. Neither the load output end nor the power socket on the surface of the GFCI has power output. Power output indicator light V 3  is not lit. 
         [0088]    Therefore, the user can conclude whether the GFCI has come to the end of its life and its work status by the monitoring the reset indicator light V 5  and power output indicator light V 3 . 
         [0089]    (2) The GFCI has a Prolonged Service Life: 
         [0090]    The present invention uses a quick trip spring  66 -A slid onto directional lock  35 . When the reset button is at a tripped state, quick trip spring  66 -A allows touch pin  28 E of reset support piece  28 A to extend downward to steadily press onto the flexible metal switch piece  88 , thus causing contact  68 B on flexible metal piece  88  to be in steady and reliable contact with contact  68 C of metal piece  66  to generate a simulated leakage current to test the device. After the reset button is reset, the quick trip spring  66 -A is in a compressed state. When the reset button is tripped, said quick trip spring  66 -A is released, thus assisting movable contacts  55  and  54  on input flexible metal pieces  51  and  50  to be quickly detached from fixed contacts  16  and  15  on power output conductors  14  and  13  and movable contacts  23  and  22  on output conductor flexible metal pieces  21  and  20  to be quickly detached from fixed contacts  53  and  53  on power output terminal metal pieces  81  and  80 . This guarantees minimal detachment time, thus reducing the arc generated by the detachment of movable and fixed contacts, and prolonging the life of the movable and fixed contacts and prolonging the life of the GFCI. 
         [0091]    (3) The GFCI has high voltage surge protection function: The GFCI of the present invention contains a pair of input power connecting pieces which has a pair of discharge metal pieces. During a high voltage surge, the discharge metal pieces of said input power connecting pieces cause a discharge of electricity through the tips of the discharge metal pieces to protect the GFCI from being damaged due to the high voltage surge. 
         [0092]    (4) The GFCI has Manual End-of-Life Detect Function: 
         [0093]    a. When a leakage current is generated through manual simulation, if the GFCI works normally and has not come to the end of its life, reset indicator light V 5  is lit, indicating that the GFCI can work normally and can be reset. After it is reset, reset indicator light V 5  goes off and power output indicator light V 3  is lit; 
         [0094]    b. When a leakage current is generated through manual simulation and the leakage current protection circuit has come to the end of its life, reset indicator light V 5  is not lit, indicating that the GFCI has come to the end of its life and the reset button is prevented from reset. The load output end of the GFCI and the single phase, three line power output sockets on the surfaces of the GFCI have no power output. The power output indicator light V 3  is not lit. 
         [0095]    (5) The GFCI has Reverse Wiring Protection: 
         [0096]    When an installer or electrician erroneously connects the hot power line inside a wall to the power output end LOAD of a ground fault circuit interrupter, the automatic testing of the GFCI through the simulated leakage current generation circuit does not work and the GFCI cannot reset. The GFCI has no power output. Reset indicator light V 5  is not lit, indicating a wiring error. It is only after the installer properly connects the wire then the reset indicator light V 5  can be lit, reset button can be reset, and the power output end of the GFCI has power output. The power output indicator light V 3  is lit. 
         [0097]    While the GFCI with an automatic end-of-life test has been described in connection with an exemplary embodiment, those skilled in the art will understand that many modifications in light of these teachings are possible, and this application is intended to cover variations thereof. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.