Abstract:
An energy-saving ground-fault circuit interrupter (GFCI) includes an electronic circuit board provided in a housing and a breaker switch mounted on and controlled by the electronic circuit board. The electronic circuit board includes a power circuit, a test circuit, a work indicator circuit, a leakage detection circuit, a neutral-line ground fault detection circuit, a silicon-controlled rectifier (SCR) circuit, and an integrated circuit. The GFCI is characterized by further including a dual-coil switch-closing circuit parallel-connected to the power circuit and is advantageous in that the breaker switch can be rapidly closed by simultaneously supplying electricity to both coils to effect strong electromagnetic attraction, is kept closed by only one of the coils after current to the other coil is cut off via the properties of capacitors, and when a circuit fault occurs, is opened via an SCR which renders the single working coil out of electricity to ensure safety.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Chinese Application No. 201610011729.8, filed Jan. 8, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to the technical field of electrical appliance protection devices. More particularly, the present invention relates to an energy-saving ground-fault circuit interrupter which closes a breaker switch rapidly with two coils and then uses only one of the coils to keep the breaker switch closed. 
         [0004]    2. Description of Related Art 
         [0005]    Ground-fault circuit interrupters (GFCIs) are designed and manufactured in accordance with the requirements set forth in the US UL943 standard. 
         [0006]    The solenoid relay in a conventional GFCI requires a high-voltage, high-power power supply mode. This mode, however, tends to bring the solenoid relay into a large-current, high-power state, in which the solenoid relay keeps generating heat and may burn as a result. 
         [0007]    To overcome the shortcomings of the prior art, the inventor of the present invention designed a novel GFCI which opens and closes a breaker switch entirely under the control of an electronic circuit, and which is more energy-saving than its conventional counterparts. 
       SUMMARY OF THE INVENTION 
       [0008]    To implement the afore-mentioned functions and overcome the shortcomings of the prior art, the present invention provides an energy-saving GFCI which incorporates the following technical solutions: 
         [0009]    An energy-saving GFCI includes an electronic circuit board and a breaker switch mounted on and controlled by the electronic circuit board. The electronic circuit board is provided in a housing formed by hermetically connecting a base and a cover and is provided with the following circuits: 
         [0010]    a power circuit composed at least of a neutral line N, a live line L, and a breaker switch SK 1  series-connected to the neutral line N and the live line L; 
         [0011]    a test circuit series-connected to the power circuit and composed at least of a test resistor Rs and a test push-button switch SK 2  series-connected together; 
         [0012]    a work indicator circuit series-connected to the power circuit and composed at least of a resistor R 13  and a light-emitting diode (LED) light series-connected together; 
         [0013]    a leakage detection circuit series-connected to the power circuit and composed at least of a leakage detection transformer L 3 , a capacitor C 6 , and a capacitor C 7 ; 
         [0014]    a neutral-line ground fault detection circuit series-connected to the power circuit and composed at least of a neutral-line ground fault detection transformer L 4 , a capacitor C 8 , and a capacitor C 9 ; 
         [0015]    a silicon-controlled-rectifier (SCR) trigger circuit composed at least of a capacitor C 5 , an SCR, and a trigger switch SK 3 ; and 
         [0016]    an integrated circuit (IC) which is electrically connected to the leakage detection circuit and the neutral-line ground fault detection circuit in order to receive respectively therefrom a leakage fault signal and a ground fault signal, and which is also electrically connected to the SCR trigger circuit in order to send thereto a shaped leakage fault trigger signal and a shaped ground fault trigger signal. 
         [0017]    The energy-saving GFCI is characterized by further including a dual-coil switch-closing circuit parallel-connected to the power circuit, wherein the dual-coil switch-closing circuit includes: 
         [0018]    a first switch-closing circuit composed of a diode D 1 , a resistor R 2 , a capacitor C 1 , a coil L 1 , a triode Q 1 , a resistor R 5 , a resistor R 6 , a resistor R 7 , a resistor R 8 , a capacitor C 3 , and a capacitor C 10 ; and 
         [0019]    a second switch-closing circuit parallel-connected to the first switch-closing circuit and composed of a diode D 2 , a resistor R 1 , a capacitor C 2 , a coil L 2 , a triode Q 2 , a resistor R 9 , a resistor R 10 , a diode D 3 , and a capacitor C 4 ; 
         [0020]    wherein the coils L 1  and L 2  have the same current direction so as to jointly generate a switch-closing electromagnetic force in the instant when they are supplied with electricity. 
         [0021]    Once the diode D 1  rectifies the current running therethrough, at least the following closed loops may be formed: 
         [0022]    a first closed loop composed of the resistor R 2  and the capacitor C 1  (this closed loop will not be formed when the capacitor C 1  is fully charged and therefore does not allow passage of current); 
         [0023]    a second closed loop composed of the resistor R 2 , the coil L 1 , the triode Q 1 , the resistor R 5 , the resistor R 6 , the resistor R 7 , and the triode Q 1  and serving to supply electricity to the coil L 1  in order for the coil L 1  to close the breaker switch SK 1 ; 
         [0024]    a third closed loop composed of the resistor R 5  and the capacitor C 10  (this closed loop will not be formed when the capacitor C 10  is fully charged and therefore does not allow passage of current); 
         [0025]    a fourth closed loop composed of the resistor R 5 , the resistor R 6 , and the trigger switch SK 3 , wherein the trigger switch SK 3  remains open when there is no circuit fault or when the GFCI is supplied with electricity and in normal operation; 
         [0026]    a fifth closed loop composed of the resistor R 5 , the resistor R 6 , the resistor R 7 , and the resistor R 8 ; 
         [0027]    a sixth closed loop composed of the resistor R 5 , the resistor R 6 , the resistor R 7 , and the capacitor C 3  (this closed loop will not be formed when the capacitor C 3  is fully charged and therefore does not allow passage of current); 
         [0028]    a seventh closed loop composed of the resistor R 5 , the resistor R 6 , the capacitor C 4 , and the diode D 3  (this closed loop will not be formed when the capacitor C 4  is fully charged and therefore does not allow passage of current); 
         [0029]    an eighth closed loop composed of the resistor R 5 , the resistor R 6 , the capacitor C 4 , the resistor R 9 , and the resistor R 10  (this closed loop will not be formed when the capacitor C 4  is fully charged and therefore does not allow passage of current); and 
         [0030]    a ninth closed loop composed of the resistor R 5  and the resistor R 6  in the first switch-closing circuit; the capacitor C 4 , the resistor R 9 , and the triode Q 2  in the second switch-closing circuit; and the resistor R 1 , the coil L 2 , and the triode Q 2  in the second switch-closing circuit. 
         [0031]    In addition, once the diode D 2  rectifies the current running therethrough, at least the following closed loops may be formed: 
         [0032]    a tenth closed loop composed of the resistor R 1  and the capacitor C 2  (this closed loop will not be formed when the capacitor C 2  is fully charged and therefore does not allow passage of current); and 
         [0033]    an eleventh closed loop composed of the resistor R 1 , the coil L 2 , and the triode Q 2  in the second switch-closing circuit; the resistor R 5  and the resistor R 6  in the first switch-closing circuit; and the capacitor C 4 , the resistor R 9 , and the triode Q 2  in the second switch-closing circuit and serving to supply electricity to the coil L 2  in order for the coil L 2  to close the breaker switch SK 1 . 
         [0034]    When the capacitors C 1 , C 2 , C 3 , C 4 , and C 10  are fully charged, the coil L 1  is supplied with electricity and continues generating an electromagnetic field to keep the breaker switch SK 1  closed, whereas the coil L 2  is out of electricity and unable to close the breaker switch SK 1  by electromagnetic attraction. 
         [0035]    When one of the leakage detection circuit and the neutral-line ground fault detection circuit detects a circuit fault, the one detecting the circuit fault sends the fault signal to the IC instantly. The IC shapes the fault signal and sends the resulting trigger signal to the SCR trigger circuit. As a result, the trigger switch SK 3  is triggered to close, causing the voltage value at the resistor R 7  to approach zero rapidly. Once the triode Q 1  is turned off, the coil L 1  becomes out of electricity and is unable to close the breaker switch SK 1  by electromagnetic attraction. 
         [0036]    In the first switch-closing circuit and the second switch-closing circuit, the resistor R 2  and the resistor R 5  are parallel-connected to each other and series-connected to the diode D 1 ; 
         [0037]    the coil L 1  and the triode Q 1  are series-connected to each other and parallel-connected to the capacitor C 1 , and this parallel-connected unit is series-connected to the resistor R 2 ; 
         [0038]    the resistor R 6  and the capacitor C 10  are parallel-connected to each other and series-connected to the resistor R 5 ; 
         [0039]    the trigger switch SK 3 , the capacitor C 4 , and the resistor R 7  are parallel-connected to one another and series-connected to the resistor R 6 ; 
         [0040]    the resistor R 8 , the capacitor C 3 , and the triode Q 1  are parallel-connected to one another and series-connected to the resistor R 7 ; 
         [0041]    the resistor R 1  is series-connected to the diode D 2 /M 7 ; 
         [0042]    the coil L 2  and the triode Q 2  are series-connected to each other and series-connected to the resistor R 1 ; 
         [0043]    the triode Q 2  and the resistor R 10  are parallel-connected to each other and series-connected to the resistor R 9 ; and 
         [0044]    the resistor R 9  and the diode D 3  are parallel-connected to each other and series-connected to the capacitor C 4 . 
         [0045]    The present invention is advantageous over the prior art in that, by supplying electricity to both coils simultaneously, a strong force of electromagnetic attraction is instantly generated to close the breaker switch rapidly; that after the breaker switch is closed, the current to one of the coils is cut off via the properties of capacitors, and electricity is supplied to only one coil to keep the breaker switch turned on; and that upon occurrence of a circuit fault, the SCR renders the single working coil out of electricity, so the breaker switch cuts off power supply to ensure safety. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0046]      FIG. 1  is a schematic circuit diagram of the GFCI of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]    To facilitate the understanding of the technical means, inventive features, objectives, and effects of the present invention, the invention is described in more detail below with reference to the accompanying drawing. 
         [0048]    The GFCI of the present invention has two working positions, namely ON and OFF. When the GFCI is in the ON position, power supply is connected to the load; when the GFCI is in the OFF position, power supply is cut off from the load. The GFCI is configured to cut off the current in the wire between the power supply and the load when a leakage fault or ground fault takes place at the load end, with a view to ensuring both personal and equipment safety. 
         [0049]    Referring to  FIG. 1 , the GFCI of the present invention includes the following circuits: 
         [0050]    a power circuit C 001  composed at least of a neutral line N, a live line L, and a breaker switch SK 1  series-connected to the neutral line N and the live line L; 
         [0051]    a test circuit C 002  series-connected to the power circuit C 001  and composed at least of a test resistor Rs and a test push-button switch SK 2  series-connected together; 
         [0052]    a work indicator circuit C 003  series-connected to the power circuit C 001  and composed at least of a resistor R 13  and a light-emitting diode (LED) light series-connected together; 
         [0053]    a leakage detection circuit C 004  series-connected to the power circuit C 001  and composed at least of a leakage detection transformer L 3 , a capacitor C 6 , and a capacitor C 7 ; 
         [0054]    a neutral-line ground fault detection circuit C 005  series-connected to the power circuit C 001  and composed at least of a neutral-line ground fault detection transformer L 4 , a capacitor C 8 , and a capacitor C 9 , wherein a resistor R 11  and a resistor R 12  are series-connected between the leakage detection circuit C 004  and the neutral-line ground fault detection circuit C 005 ; 
         [0055]    a silicon-controlled-rectifier (SCR) trigger circuit C 006  composed at least of a capacitor C 5 , an SCR, and a test push-button trigger switch SK 3 ; and 
         [0056]    an integrated circuit (IC) C 007  which is electrically connected to the leakage detection circuit C 004  and the neutral-line ground fault detection circuit C 005  in order to receive respectively therefrom a leakage fault signal and a ground fault signal, and which is also electrically connected to the SCR trigger circuit C 006  in order to send thereto a shaped leakage fault trigger signal and a shaped ground fault trigger signal. 
         [0057]    The circuitry of the GFCI further includes a dual-coil switch-closing circuit parallel-connected to the power circuit C 001 , wherein the dual-coil switch-closing circuit includes a first switch-closing circuit CL 01  and a second switch-closing circuit CL 02 . 
         [0058]    The first switch-closing circuit CL 01  is composed of a diode D 1 , a resistor R 2 , a capacitor C 1 , a coil L 1 , a triode Q 1 , a resistor R 5 , a resistor R 6 , a resistor R 7 , a resistor R 8 , a capacitor C 3 , and a capacitor C 10 . The resistor R 8 , the capacitor C 3 , and the capacitor C 10  mainly serve a filtering and voltage stabilizing function. 
         [0059]    The second switch-closing circuit CL 02  is parallel-connected to the first switch-closing circuit CL 01  and is composed of a rectifier diode D 2 , a resistor R 1 , a capacitor C 2 , a coil L 2 , a triode Q 2 , a resistor R 9 , a resistor R 10 , a diode D 3 , and a capacitor C 4 . 
         [0060]    In the first switch-closing circuit CL 01  and the second switch-closing circuit CL 02 , the resistor R 2  and the resistor R 5  are parallel-connected to each other and series-connected to the diode D 1 ; 
         [0061]    the coil L 1  and the triode Q 1  are series-connected to each other and parallel-connected to the capacitor C 1 , and this parallel-connected unit is series-connected to the resistor R 2 ; 
         [0062]    the resistor R 6  and the capacitor C 10  are parallel-connected to each other and series-connected to the resistor R 5 ; 
         [0063]    the trigger switch SK 3 , the capacitor C 4 , and the resistor R 7  are parallel-connected to one another and series-connected to the resistor R 6 ; 
         [0064]    the resistor R 8 , the capacitor C 3 , and the triode Q 1  are parallel-connected to one another and series-connected to the resistor R 7 ; 
         [0065]    the resistor R 1  is series-connected to the diode D 2 /M 7 ; 
         [0066]    the coil L 2  and the triode Q 2  are series-connected to each other and series-connected to the resistor R 1 ; 
         [0067]    the triode Q 2  and the resistor R 10  are parallel-connected to each other and series-connected to the resistor R 9 ; 
         [0068]    the resistor R 9  and the diode D 3  are parallel-connected to each other and series-connected to the capacitor C 4 ; and 
         [0069]    the coils L 1  and L 2  have the same current direction in order to jointly generate a switch-closing electromagnetic force immediately after they are supplied with electricity. 
         [0070]    Once the diode D 1  rectifies the current running therethrough, at least the following closed loops may be formed within the first switch-closing circuit CL 01  and the second switch-closing circuit CL 02 : 
         [0071]    a first closed loop composed of the resistor R 2  and the capacitor C 1  (this closed loop will not be formed when the capacitor C 1  is fully charged and therefore does not allow passage of current); 
         [0072]    a second closed loop composed of the resistor R 2 , the coil L 1 , the triode Q 1 , the resistor R 5 , the resistor R 6 , the resistor R 7 , and the triode Q 1  and serving to supply electricity to the coil L 1  in order for the coil L 1  to close the breaker switch SK 1 ; 
         [0073]    a third closed loop composed of the resistor R 5  and the capacitor C 10  (this closed loop will not be formed when the capacitor C 10  is fully charged and therefore does not allow passage of current); 
         [0074]    a fourth closed loop composed of the resistor R 5 , the resistor R 6 , and the trigger switch SK 3 , wherein the trigger switch SK 3  remains open when there is no circuit fault or when the GFCI is supplied with electricity and in normal operation; 
         [0075]    a fifth closed loop composed of the resistor R 5 , the resistor R 6 , the resistor R 7 , and the resistor R 8 ; 
         [0076]    a sixth closed loop composed of the resistor R 5 , the resistor R 6 , the resistor R 7 , and the capacitor C 3  (this closed loop will not be formed when the capacitor C 3  is fully charged and therefore does not allow passage of current); 
         [0077]    a seventh closed loop composed of the resistor R 5 , the resistor R 6 , the capacitor C 4 , and the diode D 3  (this closed loop will not be formed when the capacitor C 4  is fully charged and therefore does not allow passage of current); 
         [0078]    an eighth closed loop composed of the resistor R 5 , the resistor R 6 , the capacitor C 4 , the resistor R 9 , and the resistor R 10  (this closed loop will not be formed when the capacitor C 4  is fully charged and therefore does not allow passage of current); and 
         [0079]    a ninth closed loop composed of the resistor R 5  and the resistor R 6  in the first switch-closing circuit CL 01 ; the capacitor C 4 , the resistor R 9 , and the triode Q 2  in the second switch-closing circuit CL 02 ; and the resistor R 1 , the coil L 2 , and the triode Q 2  in the second switch-closing circuit CL 02  (when the capacitor C 4  is fully charged and therefore does not allow passage of current, this closed loop will not be formed, and consequently the coil L 2  will not be supplied with electricity). 
         [0080]    Once the diode D 2  rectifies the current running therethrough, at least the following closed loops may be formed: 
         [0081]    a tenth closed loop composed of the resistor R 1  and the capacitor C 2  (this closed loop will not be formed when the capacitor C 2  is fully charged and therefore does not allow passage of current); and 
         [0082]    an eleventh closed loop composed of the resistor R 1 , the coil L 2 , and the triode Q 2  in the second switch-closing circuit CL 02 ; the resistor R 5  and the resistor R 6  in the first switch-closing circuit CL 01 ; and the capacitor C 4 , the resistor R 9 , and the triode Q 2  in the second switch-closing circuit CL 02  and serving to supply electricity to the coil L 2  in order for the coil L 2  to close the breaker switch SK 1  (this closed loop will not be formed when the capacitor C 4  is fully charged and therefore does not allow passage of current). 
         [0083]    When the capacitors C 1 , C 2 , C 3 , C 4 , and C 10  are fully charged, only the second closed loop and the fifth closed loop are formed, in which state: 
         [0084]    the coil L 1  is supplied with electricity and continues generating an electromagnetic field to keep the breaker switch SK 1  closed, and the capacitor C 4  does not allow current to pass therethrough such that the triode Q 2  is turned off and the coil L 1  is out of electricity and unable to close the breaker switch SK 1  by electromagnetic attraction. 
         [0085]    When one of the leakage detection circuit C 004  and the neutral-line ground fault detection circuit C 005  detects a circuit fault, the one detecting the circuit fault sends the fault signal to the IC C 007  immediately. The IC C 007  shapes the fault signal received and sends the resulting trigger signal to the SCR trigger circuit C 006 . In consequence, the trigger switch SK 3  is triggered to close, causing the voltage value of the resistor R 7  to approach zero rapidly. The triode Q 1  is turned off as a result, rendering the coil L 1  out of electricity and unable to close the breaker switch SK 1  by electromagnetic attraction. The power circuit C 001  in this state is in the OFF position, meaning the load is cut off from the power supply. 
         [0086]    The working principle of the GFCI is described below with continued reference to  FIG. 1 : 
         [0087]    In this GFCI, the solenoid relay controlling the breaker switch SK 1  is a joint control mechanism consisting of the coils L 1  and L 2  and capable of providing a strong attraction force for closing the breaker switch. The coil L 1  is supplied with electricity via the second closed loop, and the coil L 2 , via both the ninth and the eleventh closed loops. 
         [0088]    When the voltage of the power supply is zero, the working voltage of the circuits in the GFCI is zero, too. In this state, no current flows through the coil L 1  or the coil L 2 , and the GFCI is in the OFF state, with the breaker switch SK 1  open to cut off the connection between the power supply and the load. 
         [0089]    When the voltage of the power supply reaches a predetermined value (typically about 80% of the normal supply voltage value), current flows through the coils L 1  and L 2  in the same direction, and in an instant, the two coils jointly generate an electromagnetic force that rapidly moves the moving contact of the breaker switch SK 1  to the stationary contact. Consequently, the GFCI is shifted to the ON state, with the power supply supplying electricity to the load. 
         [0090]    After the breaker switch SK 1  in the GFCI is automatically closed, the capacitor C 4  in the ninth or the eleventh closed loop is rapidly charged to the full via the diode D 1  and then stops the passage of current. As a result, the triode Q 2  is turned off, and the coil L 2  is out of electricity and unable to close the breaker switch SK 1  by electromagnetic attraction. At this moment, only the coil L 1  is supplied with electricity, and the coil L 1  keeps generating an electromagnetic field to maintain the breaker switch SK 1  in the closed state. The maintaining voltage of the coil L 1  is as low as 15 V, which demonstrates the advantageous energy-saving feature of the GFCI. 
         [0091]    As soon as the leakage detection transformer L 3  in the leakage detection circuit C 004  or the neutral-line ground fault detection transformer L 4  in the neutral-line ground fault detection circuit C 005  detects a circuit fault, the transformer L 3  or L 4  which has detected the circuit fault sends the fault signal to the IC C 007 . The fault signal is shaped by the IC C 007  into a trigger signal, which is then sent to the SCR in the SCR trigger circuit C 006  to trigger, or close, the trigger switch SK 3 . Once the trigger switch SK 3  is closed, the voltage value of the resistor R 7  approaches zero rapidly, so no current flows to the triode Q 1 , meaning the triode Q 1  is in the cut-off state. Now that the triode Q 1  is turned off, the coil L 1  is out of electricity and is unable to close the breaker switch SK 1  by electromagnetic attraction. Under the elastic force of the spring in the breaker switch SK 1 , therefore, the moving contact of the breaker switch SK 1  separates from the stationary contact instantly, shifting the GFCI to the OFF state, in which the power supply stops supplying electricity to the load to prevent damage attributable to the fault current in the GFCI. 
         [0092]    Once the circuit fault is cleared, the operator can press the reset push-button of the GFCI to short-circuit the SCR, thereby stopping current from passing through the SCR. Thus, the trigger switch SK 3 , which has been triggered to close by the SCR, is turned from the turned-on state to the cut-off state. Even after the reset push-button is subsequently released, the trigger switch SK 3  will stay in the cut-off state as long as the SCR does not send out the trigger signal. While the trigger switch SK 3  is in the cut-off state, no current flows through the trigger switch SK 3 , so the voltage value of the resistor R 7  is restored at once. Accordingly, current runs to the triode Q 1  to turn it on. The current also flows through the coil L 1  such that the coil L 1  generates an electromagnetic field to close the breaker switch SK 1  by electromagnetic attraction. Moreover, as the trigger switch SK 3  enters the cut-off state from the turned-on state, the capacitor C 4 , which has fully discharged through the resistors R 9  and R 10  while the circuit was cut off from the power supply, begins to be charged and allows passage of current. The triode Q 2  is thus turned on again, and the coil L 2  generates a transient magnetic force due to the current passing therethrough. This magnetic force and the magnetic force generated by the coil L 1  jointly form a strong switch-closing force that closes the breaker switch SK 1  by electromagnetic attraction again, and by doing so, the GFCI reconnects the power supply to the load. Once the capacitor C 4  is fully charged, the triode Q 2  returns from the turned-on state to the cut-off state such that the coil L 2  is once more out of electricity and unable to close the breaker switch SK 1  by electromagnetic attraction. Now, again, only the coil L 1  is supplied with electricity and continues generating an electromagnetic force to keep the breaker switch SK 1  closed. 
         [0093]    When the GFCI is used for the first time, the indicator light of the GFCI will be lit upon connection between the pins of the GFCI and the socket of the power supply, indicating that the GFCI is outputting electricity. When the test push-button of the GFCI is pressed, the indicator light goes out, indicating that the GFCI is not outputting electricity. By pressing the reset push-button, the indicator light will be lit again, indicating that the GFCI is supplied with and outputting electricity and in normal operation. 
         [0094]    The advantages, as well as the principle and major features, of the present invention have been shown and described above. As would be understood by a person of ordinary skill in the art, the present invention is not to be limited by the disclosed embodiments; the embodiments and the description serve only to elucidate the principle of the invention. The present invention can be modified and improved in many ways without departing from the spirit and scope of the invention. All such modifications and improvements should fall within the scope of patent protection sought by the applicant. The scope of patent protection sought by the applicant is defined by the appended claims and includes their equivalents.