Ground Fault Circuit Interrupter (GFCI) System and Method

Abstract

The present application relates to ground fault circuit interrupter (GFCI) systems and methods. The present application provides a wiring device, which includes: a face contact; one or more line contact arms; one or more load contact arms; and a fault detection circuit. The one or more line contact arms have an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a substantially straight portion of the line contact arm. The one or more load contact arms have a load contact positioned on a curved portion of the load contact arm. The fault detection circuit detects a fault condition in the wiring device and generates a fault detection signal when the fault condition is detected, wherein the fault detection signal electrically disconnects the face contact from the upper line contact and the lower line contact from the load contact.

Description

[0001] Divisional Application Information

[0002] This application is a divisional application of an invention patent application with an application date of December 18, 2015, application number 201580085752.5, and invention name “Ground Fault Circuit Interrupter (GFCI) System and Method”. Technical Field

[0003] The described embodiments relate to ground fault circuit interrupter (GFCI) systems and methods. Background Art

[0004] The present invention relates generally to electrical devices with switches. More particularly, the present invention relates to circuit interrupting devices, such as ground fault circuit interrupter (GFCI) devices, which switch from a "reset" or latched state to a "tripped" or unlatched state when one or more conditions are detected. Such devices consistent with embodiments of the invention disclosed herein are more reliable and have a longer life expectancy than previously known GFCI devices.

[0005] GFCI devices having contacts biased toward an open position require a latching mechanism for placing and maintaining the contacts in a closed position. Likewise, electrical devices with switches having contacts biased toward a closed position require a latching mechanism for placing and maintaining the contacts in an open position. Examples of conventional types of devices include circuit interrupting type devices such as circuit breakers, arc fault interrupters, and GFCIs, to name a few.

[0006] When the GFCI device is in the open position, the contacts may still be relatively close to each other due to the relatively small size of the GFCI device. This can result in slow plasma extinction, arcing, and relatively slow disconnection (e.g., opening) of the contacts. These conditions can result in a higher failure rate of the device due to the accumulation of residues on the contacts that can result in longer opening times and possible permanent failure. Summary of the invention

[0007] In one embodiment, the present invention solves such problems by providing a wiring device, the device comprising: a face terminal for electrically connecting to an external load; a line terminal for electrically connecting to an external power supply; a load terminal for electrically connecting to a second external load; a face contact electrically connected to the face terminal; one or more line contact arms electrically connected to the line terminal; and one or more load contact arms electrically connected to the load terminal. Each line contact arm has an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a substantially straight portion of the line contact arm. Each load contact arm has a load contact positioned on a curved portion of the load contact arm. Wherein, when the wiring device is in a closed position, the face contact and the upper line contact are electrically connected, and the lower line contact and the load contact are electrically connected, and when the wiring device is in an open position, the face contact and the upper line contact are electrically disconnected, and the lower line contact and the load contact are electrically disconnected.

[0008] In another embodiment, the present invention provides a wiring device comprising: a face contact; one or more line contact arms; one or more load contact arms; and a fault detection circuit. The one or more line contact arms have an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a substantially straight portion of the line contact arm. The one or more load contact arms have a load contact positioned on a curved portion of the load contact arm. The fault detection circuit detects a fault condition in the wiring device and generates a fault detection signal when the fault condition is detected, wherein the fault detection signal electrically disconnects the face contact from the upper line contact and the lower line contact from the load contact.

[0009] In yet another embodiment, the present invention provides a method of operating a wiring device. The method includes: providing a face contact; providing one or more line contact arms; and providing one or more load contact arms. Each line contact arm has an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a substantially straight portion of the line contact arm. Each load contact arm has a load contact positioned on a curved portion of the load contact arm. The method further includes: electrically connecting the face contact to the upper line contact; and electrically connecting the lower line contact to the load contact.

[0010] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1is a side elevation view of a self-testing GFCI outlet device according to an exemplary embodiment of the present invention.

[0012] Figure 2 yes Figure 1 00140] A side elevation view of a self-test GFCI receptacle is shown with the front cover of the housing removed.

[0013] Figure 3 yes Figure 1 00140] A side elevation view of the core assembly of a self-test GFCI outlet device is shown in FIG.

[0014] Figure 4 is in the disconnected position Figure 1 A side view of the line contact arm and the load contact arm of a GFCI receptacle is shown in FIG.

[0015] Figure 5 is in closed position Figure 1 A side view of the line contact arm and the load contact arm of a GFCI receptacle is shown in FIG.

[0016] FIG. 6A to FIG. 6D is a schematic diagram of an exemplary circuit consistent with an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0017] Before explaining the embodiments of the invention in detail, it should be understood that the invention is not limited in its application to the details of construction and arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or carried out in various ways.

[0018] Figure 1 A perspective view of a GFCI outlet 10 according to one embodiment of the present invention is illustrated. The GFCI outlet 10 includes a front cover 12 having a two-wire seat face 14 having a phase opening 16, a neutral opening 18, and a ground opening 20. Face 14 further has an opening 22 that accommodates a reset button 24, an adjacent opening 24 that accommodates a test button 28, and six corresponding circular openings 30 to 35. In some embodiments, openings 30 and 33 accommodate two corresponding indicators, such as (but not limited to) various colored light emitting diodes (LEDs). In some embodiments, openings 32 and 34 accommodate corresponding bright LEDs used as, for example, a night light. In some embodiments, opening 31 accommodates a light-conductive photocell used, for example, to control the night light LED. In some embodiments, opening 35 allows access to a set screw used to adjust the photocell device according to this embodiment and other embodiments.

[0019] GFCI outlet 10 further comprises eight fasteners 38 ( Figure 1The grounding yoke / bridge assembly 40 includes a standard mounting ear 42 protruding from the end of the GFCI outlet 10.

[0020] Figure 2 A perspective view of a GFCI outlet 10 is illustrated with the front cover 12 removed to expose the manifold 126. The manifold 126 provides support for the printed circuit board 390 and the yoke / bridge assembly 40. According to one embodiment, the manifold 126 includes four dovetail interconnects 130 that mate with corresponding recesses 132 along the upper edge of the rear cover 36. One dovetail-recess pair is provided on each of the four sides of the manifold 126 and rear cover 36, respectively.

[0021] Figure 3 8 is a side elevation view of a core assembly 80 according to one embodiment. The core assembly 80 includes a circuit board 82 that supports most of the working components of the socket, including FIG. 6A to FIG. 6D , and a sense transformer 84 and a grounded neutral transformer 85 (not shown). Line contact arms 94, 96 pass through the transformers 84, 85 with an insulating separator 98 between the arms. The line contact arms 94, 96 are cantilevered with their respective distal ends carrying phase and neutral line contacts 102, 104. The load contact arms 98, 100 are also cantilevered with their respective distal ends carrying phase and neutral load contacts 101, 103. The resiliency of the cantilevered contact arms biases the line contacts 102, 104 and the load contacts 101, 103 away from each other. The load contact arms 98, 103 rest on a movable contact bracket 106 made of an insulating (preferably thermoplastic) material.

[0022] Figure 4 is a side view of the line contact arm 94 and the load contact arm 98 in the open position according to one embodiment. Figure 4 Further illustrating load contact 101 (e.g., phase load contact or neutral load contact), line contact 102 (e.g., phase line contact or neutral line contact), movable contact carrier or latch housing 106, face 108, and face contact 109 (e.g., phase face contact or neutral face contact). In some embodiments, face 108 is the bottom portion of manifold 126. Although Figure 4Although not illustrated in the drawings, the line contact arm 96, the load contact arm 100, the load contact 103 (e.g., a phase load contact or a neutral load contact) and the line contact 104 (e.g., a phase line contact or a neutral line contact) are similar to Figure 4 and 5 Also, it should be noted that according to various embodiments, Figure 4 and 5 The contact and contact arm configurations shown and described are also provided in the Figures 1 to 3 In the device shown and described.

[0023] The line contact arm 94 includes a first straight or substantially straight portion 110 and a first bent portion 115. The first straight portion 110 includes the lower line contact 102a, and the first bent portion 115 includes the upper line contact 102b. In some embodiments, the line contact arm 94 is bent at an angle of about three degrees, but the line contact arm can be bent at an angle ranging from about three degrees to about six degrees. The lower line contact 102a can be coupled to the line contact arm 94 before the upper line contact 102b through an insertion hole. In some embodiments, the lower line contact 102a and the upper line contact 102b are coupled to the line contact arm 94 via rivets.

[0024] The load contact arm 98 includes a second straight or substantially straight portion 120 and a second curved portion 125. The second curved portion 125 has a load contact 101. In some embodiments, the load contact arm 98 is bent at an angle of about three degrees to about six degrees. In some embodiments, the load contact 101 is coupled to the load contact arm 98 via rivets.

[0025] Figure 5 is based on Figure 4 FIG. 1 is a side view of the line contact arm 94 and the load contact arm 98 in the closed position of the embodiment of FIG. The line contact arm 94 is bent downward so that when in the closed position, the upper line contact 102b is in substantially flat contact with the face contact 109. In addition, the load contact arm 98 is bent downward so that when in the closed position, the load contact 101 is in substantially flat contact with the lower line contact 102a.

[0026] In operation, when the line contact arms 94, 96 and the load contact arms 98, 100 change from a closed position to an open position or from an open position to a closed position, an erasing action is performed. In addition, when the line contact arms 94, 96 and the load contact arms 98, 100 are in a reset condition, the curved portion of the contact arms adds a torque. This erasing action and the added torque allow the contacts to float and maintain connection even when the GFCI outlet 10 moves. The erasing action, the added torque, and the curved portion result in a relatively large opening between the contacts and a relatively fast disconnection between the contacts when the device trips. The relatively large opening and relatively fast disconnection can result in relatively fast plasma extinguishing, which can reduce the possibility of arc strike, among other things.

[0027] The relatively large opening or space between the contacts additionally enables cooler operation of the GFCI outlet 10 by allowing more air and surface cooling. The relatively large opening also prevents arcing between the contacts, which can occur during high voltage operation or when the brush arms lose spring force. In some embodiments, the contacts are approximately 0.060" away from each other when in the open position. The curved portions of the line contact arms 94, 96 and the load contact arms 98, 100 move the contacts further away from the movable contact bracket 106, thereby preventing any potential melting from occurring.

[0028] FIG. 6A to FIG. 6D is a schematic diagram of a circuit according to one embodiment of the present invention. FIG. 6A to FIG. 6D The circuit shown in FIG. 1 or its various subcircuits may be implemented in a variety of electrical wiring devices, however, for the purpose of description, they are combined here in Figures 1 to 5 The use of the GFCI receptacle device shown in the FIG. 6A to FIG. 6D circuit.

[0029] FIG. 6A to FIG. 6D The circuit of includes a phase line terminal 326 and a neutral line terminal 328 for electrical connection to an AC power source (not shown), such as a 60 Hz, 120 volt rms power source used for household power in the United States. FIG. 6A to FIG. 6D Circuits and software resident on and implemented with the circuits are intended to accommodate other power delivery systems. Such modifications, and the resulting circuits and wiring devices that will ultimately use the circuits and software, are contemplated by the inventors and are considered to be within the spirit and scope of the invention described herein. For example, power delivery systems using different voltages and frequencies are within the scope of the invention.

[0030] refer to FIG. 6A to FIG. 6D , the phase conductor 330 and the neutral conductor 332 are connected to the line terminals, respectively, and each passes through a sensing transformer 334 and a grounded neutral transformer 336, which are part of the detection circuit described below. By way of example, the line terminals correspond to the above Figure 1 The input terminal screws 326, 328 in FIG. 1 and the line conductors 330, 332 represent the line contact arms 94, 96, respectively, as described above with respect to FIG. Figure 3 Each of the line conductors 330, 332 has a respective fixed end connected to the line terminal, and each includes a respective movable contact, such as the contacts 102, 104 from the embodiment described above. The face phase conductor 338 and the face neutral conductor 340 each include an electrical contact fixed thereto, such as the contact 109 from the embodiment described above. The face conductors 338, 340 are electrically connected to respective face terminals 342, 344, and in the embodiment shown are integral with the face terminals, to which the plugs from the load device (not shown) (e.g., an appliance) are to be connected when the electrical socket device is in use.

[0031] According to this embodiment FIG. 6A to FIG. 6D The circuit shown in FIG. 1 also includes optional load phase terminal 346 and load neutral terminal 348, respectively, which are electrically connected to a downstream load (not shown), such as one or more additional outlet devices. The load terminals 346, 348 are connected to cantilevered load conductors 277, 278, respectively, each of which includes a movable load contact 101, 103 ( Figure 4 and 5 The load contacts 101 and 103 are placed on the corresponding line contacts 102 and 104 ( Figure 4 and 5 ) and surface contact 109( Figure 4 and 5 ) below and coaxially therewith so that when the line conductor moves toward the load and the surface conductor, the three sets of contacts mate and are electrically connected together. When the device is in this condition, it is said to be "reset" or in a reset state.

[0032] Detector circuit

[0033] Continue to refer FIG. 6A to FIG. 6D , the detector circuit 352 includes transformers 334, 336 and a GFCI integrated circuit device (GFCI IC) 350. According to an embodiment of the present invention, the GFCI IC 350 is a well-known 4141 device, such as the RV4141 device made by Fairchild Semiconductor Corporation. FIG. 6A to FIG. 6D Other GFCI IC devices may be used in the circuit of FIG. 1 and such modifications are within the spirit and scope of the present invention.

[0034] The GFCI IC device 350 receives electrical signals from various other circuit components, including transformers 334, 336, and detects one or more faults, such as real faults, simulated faults, or self-test ground faults, and real or simulated grounded neutral faults. For example, when sufficient current imbalance occurs in the line conductors 330, 332, a net current flows through the transformers 334, 336, causing magnetic flux to be generated around at least the transformer 334. This magnetic flux causes a current to be induced on the conductor 333, which is wrapped around the sensing transformer 334. The respective ends of the conductor 333 are connected to the positive and negative inputs of the sense amplifier of the GFCI IC device 350 at input ports V-REF and VFB, respectively. The induced current on the conductor 333 causes a voltage difference at the input to the sense amplifier of the GFCI IC 350. When the voltage difference exceeds a predetermined threshold, a detection signal is generated at one or more of the outputs of the GFCI IC 350, such as the SCR trigger signal output port (SCR_OUT). The threshold used by GFCI IC 350 is determined by the effective resistance connected between the operational amplifier output (OP_OUT) and the positive input (VFB) to the sense amplifier.

[0035] The current imbalance on the line conductors 330, 332 is caused by a real ground fault, a simulated ground fault, or a self-test ground fault. FIG. 6A to FIG. 6D The test switch 354 in the closure (when the test button 28 ( Figure 1 ) occurs, a simulated ground fault is generated. As described in further detail below, when the automatic monitoring circuit 370 initiates an automatic monitoring test sequence including the current generated on the independent conductor 356, a self-test fault will occur.

[0036] According to an embodiment of the present invention, when the test switch 354 is closed, some of the current flowing in the line conductors 330, 332 and the load conductors 338, 340 is shunted from the phase plane conductor 338 around the sense transformer 334 (and from the phase load conductor 277 when the device is in the reset state) and through the resistor 358 to the neutral line conductor 332. By shunting some of the current through the resistor 358 in this manner, an imbalance is created in the current flowing through the conductor 330 and the current flowing in the opposite direction through the conductor 332. When the current imbalance, i.e., the net current flowing through the conductors through the sense transformer exceeds a threshold value (e.g., 4 to 5 mA), the detector circuit 352 detects this simulated ground fault and activates the SCR output (SCR_OUT) of the GFCI IC 350.

[0037] When the SCR output of GFCI IC 350 is activated, the gate of SCR 360 is turned on, thereby allowing current to flow from the phase line conductor 330 through diode 359 and SCR 360. The current flowing through SCR 360 turns on the gates of SCR 361 and SCR 369. When SCR 361 is turned on, current flows from the phase line conductor 330 through the secondary coil 363 of the dual coil solenoid 362, fuse 365, diode 367, and SCR 361. In addition, when SCR 369 is turned on, current flows from the phase line conductor 330 through the primary coil 364 of the dual coil solenoid 362, fuse 372, diode 374, and SCR 369. The current flowing through the two coils 363, 364 generates a magnetic field that moves the armature within the solenoid 362. When the solenoid armature moves, it causes a contact carrier (e.g., a contact carrier) that is part of the interrupt device 315 to be turned on. Figure 3 106) unlatched, and the bracket drops under the natural bias of the line conductors 330, 332, that is, away from the face conductors 338, 340 and the load conductors 277, 278. As a result of the successful manual simulated fault test sequence, the device is now said to be "tripped", and the device will not deliver power to the load until it is reset. The time taken from the closing of the momentary switch 354 until the device is tripped and current no longer flows from the phase line conductor 330 to either of the face and load conductors and through the solenoid coils 363, 364 is so short that the fuses 365, 372 remain unbroken.

[0038] Manual test via reset operation

[0039] Continue to refer FIG. 6A to FIG. 6D , for example by pressing the reset button 24 ( Figure 1 ) to close reset switch 300 also initiates a test operation. Specifically, when reset switch 300 is closed, the voltage supply output VS of GFCI IC 350 is electrically connected to the gate of SCR 360 through conductor 308, thereby turning on SCR 360. When SCR 360 is turned on, current is drawn from line conductor 330 through diode 359 and SCR 360, and finally to ground. Similar to the situation when SCR 360 is turned on by pressing the test button (as previously discussed), turning on SCR 360 by pressing the reset button also causes SCR 361 and SCR 369 to turn on and current to flow through solenoid coils 363, 364. The current flowing through coils 363, 364 of solenoid 362 generates a magnetic field at the solenoid and actuates and moves the armature within the solenoid. In typical (e.g., non-test) conditions, actuating the armature in this manner trips the device, such as when an actual fault occurs.

[0040] However, when the reset switch 300 is closed, the device is likely already in a tripped condition, i.e., the contacts of the line, face, and load conductors are electrically isolated. That is, after the device has tripped, the reset button is typically pressed to re-latch the contact carrier and return the line, face, and load contacts to electrical contact ( Figure 5 326, 328). If the armature of the solenoid 362 fails to activate when the reset button is pressed, and the reset mechanism including the contact bracket fails to engage the reset plunger when it returns after the reset button is released, the device will not reset. Therefore, if, for example, the device has not been wired to the AC power line, or it has been wired incorrectly, that is, the device has been wired with AC power that is not connected to the line terminals 326, 328, then no power is applied to the GFCI IC 350. If no power is applied to the GFCI IC 350, the gate of the SCR 360 cannot be driven by the SCR output of the GFCI IC 350 or when the static button is pressed. In this condition, the device will not be able to reset. By ensuring that the device is shipped to the user in a tripped condition, the incorrect wiring condition can be prevented according to the wiring device consistent with the embodiments of the present invention. Because the device cannot be reset until AC power is properly applied to the line terminals, the incorrect wiring condition can be prevented.

[0041] Automatic monitoring circuit

[0042] Continue to refer FIG. 6A to FIG. 6D , the automatic monitoring circuit 370 includes a programmable device 301. The programmable device 301 can be any suitable programmable device that can be programmed to implement the automatic monitoring routine, such as a microprocessor or microcontroller, as explained in detail below. FIG. 6A to FIG. 6D In the embodiment shown in FIG. 3 , the programmable device 301 is implemented by an ATMEL.TM. microcontroller from the ATtiny 10 series. It can also be implemented by a microchip microcontroller such as PIC10F204 / 206.

[0043] According to the basis FIG. 6A to FIG. 6D , the microcontroller 301 initiates the automatic monitoring routine approximately every three (3) seconds by setting a software automatic monitoring test flag. The automatic monitoring test flag initiates an automatic monitoring routine within the circuit interrupt device and confirms that the device is operating properly, or in some cases, determines that the circuit interrupt device has reached its end of life (EOL). When the result of running the automatic monitoring routine is positive (i.e., successful), the automatic monitoring circuit enters a sleep state until the microcontroller 301 sets the test flag again and initiates another automatic monitoring routine.

[0044] If the result of the automatic monitoring routine is negative, such as an inability to determine that the circuit interrupting device is functioning properly, or a determination that the device is not actually operating properly, then a fault counter is incremented, and when instructed by a software program stored in a memory within the device, the microcontroller 301 initiates another automatic monitoring routine. In addition to incrementing the fault counter, a temporary indication of the fault is provided. For example, according to an embodiment of the present invention, when such a fault occurs, the I / O port GP0 of the microcontroller 301 is controlled as an output, and the light emitting diode (LED) 376 is controlled to flash, for example, one or more times, to indicate the fault to the user. If the fault counter reaches a predetermined value, i.e., a certain number of negative results of the automatic monitoring routine, which are stored and implemented in software, the automatic monitoring routine invokes an end-of-life (EOL) sequence. The EOL sequence includes one or more of the following functions: (a) indicating that the EOL has been reached, such as by continuously flashing or illuminating an indicator light and / or generating an audible sound, (b) attempting to trip the device, (c) preventing device reset attempts, (d) storing the EOL event in non-volatile memory, such as in the event of a power failure, and (e) clearing the EOL condition when the device loses power.

[0045] According to this embodiment, when the auto-monitoring software determines that it is time to run the auto-monitoring routine, i.e., the determination is made based on the auto-watchdog timer, a stimulus signal 302 is turned on at the I / O port GP1 of the microcontroller 301. When the stimulus signal is turned on, current flows through the resistor 303 and a voltage is generated at the base of the transistor 304, thereby turning on the transistor. When the transistor 304 is turned on, current flows from the dc voltage supply 378 through the resistor 305, which is, for example, a 3k-ohm resistor, and continues to flow through the electrical conductor 356 and the transistor 304 to ground. With respect to the dc voltage source 378, according to an embodiment of the present invention, the value of this voltage source is designed to be between 4.1 volts dc and 4.5 volts dc, but the value of this voltage supply can be any other suitable value, as long as the value used fully considers the other circuit functionality described below.

[0046] According to this exemplary embodiment, electrical conductor 356 is a wire, but may also be a conductive trace on a printed circuit board. Conductor 356 is connected to resistor 305 at one end, passes through sensing transformer 334, and wraps around the core of the transformer approximately ten (10) times, and is connected at its other end to the collector of transistor 304. Thus, when the software auto-monitor test flag is set in microcontroller 301 and transistor 304 is turned on, current flows through conductor 356, which comprises an independent conductor separate from phase line conductor 330 and neutral line conductor 332, and also passes through the center of sensing transformer 334.

[0047] If the circuit interruption device according to an embodiment of the present invention is functioning properly, as current flows through conductor 356 and through the sensing transformer, magnetic flux is generated at sensing transformer 334. The flux generates a signal on conductor 333 that is detected by detection circuit 352 (including GFCI IC device 350). According to this embodiment, when device 350 detects the flux generated at sensing transformer 334, the voltage level at one of the I / O ports of device 350 increases, such as at FIG. 6A to FIG. 6D The voltage level at the output port labeled CAP in FIG. 1 increases, thereby increasing the voltage on conductor 306 .

[0048] According to this embodiment, capacitor 307 is connected between the CAP I / O port of microcontroller 301 and ground. As is known in the art, attaching a capacitor directly between the CAP output of the 4141 GFCI IC device and ground causes the SCR trigger signal (SCR_OUT) output from the GFCI IC device 350 to be delayed by a predetermined time period. The amount of time the trigger signal is delayed is typically determined by the value of the capacitor. However, according to an embodiment of the present invention, capacitor 307 is not directly connected between the CAP output and ground. Instead, capacitor 307 is also connected to the ADC I / O port GP0 of microcontroller 301 via a circuit path that includes a diode 310 in series with a resistor 311 (e.g., 3M-Ohm), which completes a voltage divider circuit with a resistor 312 (e.g., 1.5M-Ohm). This additional circuit connected to the capacitor at the CAP output of the GFCI IC device 350 draws current from the delay capacitor.

[0049] By measuring the value of the signal at the ADC I / O port (GP0) and confirming that it is above a certain level, it can be determined whether the detection circuit 352 properly detects the self-test fault signal generated on the conductor 356, and can further confirm whether the GFCI IC device 350 is able to generate the appropriate SCR trigger signal. And, in order to avoid tripping the device during a self-test automatic monitoring fault, before outputting the drive signal at SCR_OUT of the GFCI IC device 350, the voltage at the capacitor 307 is measured and proper self-test fault detection is confirmed.

[0050] If the current drawn on capacitor 307 is too high, GFCI IC device 350 may not operate properly. For example, if as little as 3 to 4 milliamps of current is drawn from capacitor 307, a grounded neutral condition that is also intended to be detected by GFCI IC device 350 may not be accurately detected, e.g., in accordance with UL requirements, because the SCR trigger signal (SCR_OUT) will not be activated within the necessary amount of time. According to an embodiment of the present invention, less than about 1.3 milliamps, or about 5% of the specified delay current of GFCI IC device 350 is drawn for ADC I / O port GPO of microcontroller 301. This smaller current drawn from capacitor 307 does not affect the device's ability to properly detect a true ground fault and / or a true grounded neutral fault.

[0051] According to this embodiment, approximately 50 nanoamps of current are drawn from capacitor 307. Parallel resistors 311 and 312 connected to ADCI / O port GP0 of microcontroller 301 produce a 4.5 megohm drain, which limits the current drawn from capacitor 307 to a maximum of 1.0 microamps. GFCI IC device 350 uses approximately 40 milliamps of current to generate the SCR trigger, but microcontroller 301 only requires approximately 50 nanoamps to read the SCR trigger signal from capacitor 307 before outputting the SCR trigger signal from SCR_OUT. Therefore, by selecting the proper value for capacitor 307, in combination with appropriate value selection for resistors 311 and 312 and diode 310, it is possible to maintain the correct delay for the SCR trigger signal (SCR_OUT) from GFCI IC device 350 and use the ADC in microcontroller 301 to measure the signal at the ADC input (GP0) to determine whether the detection circuit 352 has properly detected the test signal on conductor 356.

[0052] It should also be noted that FIG. 6A to FIG. 6D In the embodiment shown in FIG. 3 , LED 376 is also connected to the ADCI / O port (GP0) of microcontroller 301. Therefore, whether LED 376 is conductive or not does not affect the drain on capacitor 307, the delay of the SCR trigger signal, and the ability of microcontroller 301 to properly measure the signal output from the CAP I / O port of GFCI IC device 350. FIG. 6A to FIG. 6D , LED 376 is selected so that it does not turn on and begin conducting during the time when microcontroller 301 is measuring the signal from the CAP output of GFCI IC device 350. For example, LED 376 is selected so that its turn-on voltage is approximately 1.64 volts or higher, according to FIG. 6A to FIG. 6DThe circuit shown in , can measure the voltage at I / O port GP0. In addition, in order to prevent any signal from being added to capacitor 307 when LED 376 is being driven, a diode 310 is provided.

[0053] According to this embodiment, the circuit path including the diode 310 and the voltage divider 311, 312 is connected to the I / O port GPO of the microcontroller 301, which acts as an input to an analog-to-digital converter (ADC) within the microcontroller 301. The ADC of the microcontroller 301 measures the increased voltage established by the charging action of the capacitor 307. When the predetermined voltage level is reached, the microcontroller 301 turns off the auto-monitoring stimulus signal 302, which in turn turns off the transistor 304, thereby stopping the current on the conductor 356 and thus stopping the flux generated at the sensing transformer 334. When this occurs, the microcontroller 301 determines that the qualified auto-monitoring event has successfully passed, and if the current count is greater than zero, decrements the auto-monitoring failure counter.

[0054] In other words, according to this embodiment, the microcontroller 301 repeats the automatic monitoring routine according to a predetermined schedule. The automatic monitoring routine is run as needed at any interval from every few seconds to every month, etc., based on a software program stored in a memory within the microcontroller 301. When the routine is initiated, flux is generated at the sense transformer 334 in a manner similar to the manner in which flux would be generated if an actual ground fault had occurred or if a simulated ground fault had been manually generated, such as by pressing a test button (as described above).

[0055] However, there is a difference between the automatic monitoring (self-test) fault generated by the automatic monitoring routine and an actual ground fault or a simulated fault generated by pressing the test button. When an actual or simulated ground fault occurs, a difference in the currents flowing in the phase conductor 330 and the neutral conductor 332, respectively, should be generated. That is, the current on conductor 330 should be different from the current on conductor 332. This differential current flowing through the sense transformer 334 is detected by the GFCI IC device 350, which drives a signal on its SCR_OUT I / O port to activate the gate of SCR 360 and turn it on. When SCR 360 is turned on, current is drawn through coils 363, 364, which causes the interrupt device 315 to trip, causing the contact bracket to drop, which in turn causes the line, face, and load contacts to separate from each other (such as Figure 4 ). Therefore, it is possible to prevent current from flowing through the phase conductor 330 and the neutral conductor 332 to the phase plane terminal 342 and the neutral plane terminal 344 and the phase load terminal 346 and the neutral load terminal 348, respectively.

[0056] In contrast, when the automatic monitoring routine is performed in accordance with the present invention, no differential current is generated on the phase conductor 330 and the neutral conductor 332, and the interrupting device 315 is not tripped. Rather, during the automatic monitoring routine, the flux generated at the sensing transformer 334 is the result of current flowing through the conductor 356, which is electrically separated from the phase conductor 330 and the neutral conductor 332. The current generated on the conductor 356 is present only for a short period of time, such as less than the delay time established by the capacitor 307 discussed previously.

[0057] If the voltage established at the input to the ADC input (GP0) of the microcontroller 301 reaches the programmed threshold within this predetermined time period during the automatic monitoring routine, then it is determined that the detection circuit 352 successfully detected the current flowing through the core of the sense transformer 334, and the automatic monitoring event is considered to have passed. Therefore, the microcontroller 301 determines that the detection circuit 352 including the GFCIIC device 350 is operating properly. Because the current flowing through the sense transformer 334 during the automatic monitoring routine is designed to be substantially similar in magnitude to the differential current flowing through the transformer during the simulated ground fault (e.g., 4 to 6 mA), it is determined that the detection circuit 352 will be able to detect the actual ground fault and provide the appropriate drive signal to the SCR 360 to trip the interrupter 315.

[0058] Alternatively, the automatic monitoring circuit 370 may determine that the automatic monitoring routine has failed. For example, if the voltage at the ADC input at the GP0 of the microcontroller 301 takes longer than a predetermined time period to reach a given voltage during the automatic monitoring routine, then the automatic monitoring event is determined to have failed. If this occurs, the automatic monitoring failure score is incremented and the failure is indicated visually or audibly. According to one embodiment, when an automatic monitoring event fails, the ADC port (GP0) of the microcontroller 301 is converted to an output port, and a voltage is placed on the conductor 309 via the I / O port GP0, which the microcontroller first converts to an output port. This voltage at the GP0 generates a current on the conductor 309, which flows through the indicator LED 376 and the resistor 380 to ground. Subsequently, the ADC I / O port (GP0) of the microcontroller 301 is converted back to an input port and is ready for the next scheduled automatic monitoring event.

[0059] According to this embodiment, when an automatic monitoring event failure occurs, the indicator LED 376 is illuminated only during the time period when the I / O port is converted to output and an output voltage is generated at the port, otherwise the LED 376 remains dim or unilluminated. Therefore, if the automatic monitoring routine is run, for example, every three (3) seconds, and the event failure only occurs once or sporadically, then the event is likely to go unnoticed by the user. On the other hand, if the failure occurs regularly, as would occur if one or more of the components used in the automatic monitoring routine were permanently disabled, then the microcontroller 301 repeatedly turns the indicator LED 376 on for 10 milliseconds and off for 100 milliseconds, thereby drawing attention to the device and informing the user that the critical functionality of the device has been compromised. Conditions that cause the automatic monitoring routine to fail include one or more of the following: an open differential transformer, a closed differential transformer, no power to the GFCI IC, an open solenoid, the SCR trigger output of the GFCI IC is continuously high, and the SCR output of the GFCI IC is continuously low.

[0060] According to yet another embodiment, if the auto-monitoring failure score reaches a predetermined limit, such as seven (7) failures in one (1) minute, then the microcontroller 301 determines that the device is no longer safe and has reached its end of life (EOL). If this occurs, a visual indicator is activated to warn the user that the circuit interrupting device has reached the end of its useful life. For example, when this EOL state is determined, the ADC I / O port (GP0) of the microcontroller 301 is converted to an output port, similar to the case when a single fault is recorded as described above, and a signal is periodically placed on the conductor 309 via the GPO, even if the LED 376 flashes at a rate of, for example, 10 milliseconds on and 100 milliseconds off, or a signal is continuously placed on the conductor 309 to permanently illuminate the LED 376. At this point, the auto-monitoring routine is also stopped.

[0061] In addition to blinking or continuously lighting the LED 376, according to yet another embodiment, when EOL is determined, an optional audible alarm circuit 382 on the printed circuit board (PCB) 390 is also activated. In this case, the current through the LED 376 establishes a voltage on the gate of the SCR 384, so that the SCR 384 can be turned on continuously or intermittently according to the output signal of the GPO from the microcontroller 301. When the SCR 384 is turned on, current is drawn from the phase line conductor 330 to activate the audible alarm 386 (e.g., a buzzer), which provides additional notification to the user of the device that the device has reached the end of its useful life (i.e., EOL). For example, with respect to an embodiment of the present invention, the audible alarm circuit 382 includes a parallel RC circuit including a resistor 387 and a capacitor 388. As current is drawn from the phase line conductor 330, the capacitor 388 charges and discharges at a rate controlled by the value of the resistor 387, causing the buzzer 386 to issue the desired intermittent alarm.

[0062] Yet another aspect of this embodiment includes a dimmable LED circuit 396. Circuit 396 includes transistor 398; LEDs 400, 402; light sensor 404 (e.g., a photocell), and resistors 406-408. When ambient light (e.g., the amount of light near a circuit interrupting device according to an embodiment of the present invention) is increasing, light sensor 404 reacts to the ambient light level to apply an increased impedance to the base of transistor 398 to dim the LEDs as the ambient light increases. Alternatively, when the ambient light decreases, such as as night begins to fall, the current flowing through sensor 404 increases accordingly. As the ambient light level decreases, LEDs 400 and 402 illuminate brighter and brighter, thereby providing a controlled light level near the device.

[0063] FIG. 6A to FIG. 6D Yet another embodiment of the present invention shown in includes a mechanism for providing data to the microcontroller 301 regarding whether the device is tripped or in a reset condition. FIG. 6A to FIG. 6D326, 328), an optocoupler 392 is connected between the phase and neutral load conductors 277, 278 and an I / O port (GP3) of the microcontroller 301. The microcontroller 301 uses the value of the signal (voltage) at port GP3 ​​to determine whether the GFCI IC device 350 is supplied with power, and whether the device is tripped or in a reset condition. When the GFCI IC device 350 is powered, such as via its voltage input port (LINE), which occurs when AC power is connected to the line terminals 326, 328, a voltage is generated at the output port (VS). This voltage drops across the Zener diode 394, which is provided to maintain the voltage supplied to the microcontroller within an acceptable level. The diodes 366, 368 connected between the phase line conductors and the power supply input port (LINE) of the GFCI IC 350 ensure that the voltage level supplied to the GFCI IC and VS outputs remains below approximately 30 volts. The voltage signal dropped across the Zener diode 394 is connected to the input port GP3 ​​of the microcontroller 301. If the microcontroller 301 does not measure a voltage at GP3, it determines that the GFCI IC device 350 is not supplying power and declares EOL.

[0064] Alternatively, if the microcontroller 301 measures a voltage at GP3, then based on the value of the voltage, it determines whether the device is tripped or in a reset state. FIG. 6A to FIG. 6D In the circuit of FIG. 1 , if the voltage measured at GP3 ​​is between 3.2 volts and 4.0 volts, such as between 76% of VCC and 100% of VCC, then it is determined that there is no power at the face (342, 344) and load (346, 348) contacts, and therefore the device is in a tripped state. If the voltage at GP3 ​​is between 2.4 volts and 2.9 volts, such as between 51% of VCC and 74% of VCC, then it is determined that there is power at the face and load contacts, and the device is in a reset state.

[0065] According to yet another embodiment, when EOL is determined, the microcontroller 301 attempts to trip the interrupt device 315 in one or both of the following ways: (a) by maintaining the stimulus signal on the third conductor 356 into the start-up half-cycle of the AC wave, and / or (b) by generating a voltage at the EOL port (GP2) of the microcontroller 301. When EOL has been declared, for example because the automatic monitoring routine has failed a required number of times and / or no power is being supplied from the supply voltage output (VS) of the GFCI IC device 350, the microcontroller 301 generates a voltage at the EOL port (GP2). Optionally, the microcontroller 301 may also use the value of the input signal at GP3 ​​(as described above) to further determine whether the device is already in a tripped state. For example, if the microcontroller 301 determines that the device has been tripped, such as the load and face contacts are not electrically connected to the line contacts (such as Figure 4), then the microcontroller 301 may determine that it is unnecessary to drive SCR 369 and / or SCR 361 to attempt to open the contacts and trip the device, and therefore does not drive SCR 369 and SCR 361 via GP2.

[0066] The voltage at GP2 directly drives the gate of SCR 369 and / or SCR 361 to turn on SCR 369 and / or SCR 361, thereby enabling it to conduct current and activate solenoid 362. More specifically, when SCR 369 and / or SCR 361 is turned on, current is drawn through coil 364 of dual coil solenoid 362. For example, dual coil solenoid 362 includes: an inner primary coil 364, which includes an 800-turn, 18-ohm, 35 AWG coil; and an outer secondary coil 363, which includes a 950-turn, 16.9-ohm, 33 AWG coil. Further details of the construction and functionality of dual coil 362 can be found in U.S. patent application Ser. No. 13 / 422,797, which is assigned to the same assignee as the present application and is incorporated herein by reference in its entirety.

[0067] As described above, when it is determined via the automatic monitoring routine that the detection circuit 352 has not successfully detected a ground fault, e.g., it has not detected flux due to current flowing in the conductor 356, or has not otherwise generated a drive signal at the SCR_OUT output port of the GFCI IC device 350 to drive the gate of the SCR 360 after such detection, the microcontroller 301 determines EOL and attempts to trip the interrupt device 315 by the method mentioned above. Specifically, the microcontroller 301 attempts to directly trip and directly drive the primary coil 364 through the alternate path GP2 to the SCR 369 and SCR 361. However, there is at least one difference between the signal on the conductor 356 when the automatic monitoring routine is operating normally and the signal on the conductor 356 generated when the EOL is determined. That is, under the EOL condition, GP2 supplies energy for SCR361 and SCR369 to be triggered and coils 362 and 363 to be energized, thereby activating solenoids 362 and 369 to trip the interrupt device 315.

[0068] If the interrupt device 315 is disconnected, or if the interrupt device 315 is already disconnected, then the power indicator circuit 321 will be disconnected. FIG. 6A to FIG. 6D, the power indicator circuit 321 includes an LED 322 in series with a resistor 323 and a diode 324. The cathode of the LED 322 is connected to the neutral load conductor 278, and the anode of the diode 324 is connected to the phase load conductor 277. Thus, when power is available at the load conductors, that is, when the device is powered and in a reset state, current is drawn through the power circuit on each alternating half cycle of the AC power, thereby illuminating the LED 322. On the other hand, if power is not available at the load conductors 277, 278, for example because the interrupt device 315 is open or tripped, or the device is reset but power is not applied, then the LED 322 will be dim or not illuminated.

[0069] Additional embodiments and aspects thereof related to automatic monitoring functionality consistent with the present invention are provided below, as well as further discussion of some of the aspects already described.

[0070] When the self-test GFCI device is properly installed, the sinusoidal AC waveform discussed herein is connected to the phase line terminal 326 and the neutral line terminal 328. According to one embodiment, the AC waveform is a 60 Hz signal comprising two half cycles: a positive 8.333 millisecond half cycle and a negative 8.333 millisecond half cycle. A so-called "start" half cycle refers to a particular half cycle, either positive or negative, during which a gate trigger signal to SCR 360 causes the respective gates of SCR 361 and SCR 369 to be driven, and the corresponding respective solenoid coils 363, 364 to conduct current, thereby "starting" solenoid 362 and causing the armature of the solenoid to shift. A "non-start" half cycle refers to an alternate half cycle of the AC waveform, i.e., a negative or positive half cycle, during which current does not flow through the SCR or its respective solenoid coil, regardless of whether the SCR gate is triggered. According to an embodiment of the present invention, whether a positive or negative half cycle is a start half cycle is determined by a diode or some other switching device placed in series with the respective solenoid coil. For example, in FIG. 6A to FIG. 6D , diodes 359, 374, and 367 are configured so that the positive half cycle is the "start-up" half cycle for SCRs 360, 369, and 361, respectively.

[0071] According to yet another embodiment of a circuit interruption device consistent with the present invention, microcontroller 301 optionally monitors AC power input to the device. For example, a 60 Hz AC input electrically connected to phase line terminal 326 and neutral line terminal 328 is monitored.

[0072] More specifically, a full 60 Hz AC cycle takes approximately 16.333 milliseconds to complete. Therefore, in order to monitor and confirm the receipt and stabilization of the AC waveform, a timer / counter within the microcontroller 301 is implemented. For example, within a three (3) second automatic monitoring window, the 60 Hz input signal is sampled once every millisecond to identify the leading edge, that is, the position where the signal changes from a negative value to a positive value. When a leading edge is detected, a flag is set in software and the count is incremented. At the end of the three (3) second test period, the count result is divided by 180 to determine whether the frequency is within a specified range. For example, if the frequency is stable at 60 Hz, then the result of dividing by 180 will be 1.0 because there are 180 positive edges and 180 cycles within three (3) seconds of a 60 Hz signal. If it is determined that the frequency is not within a given range, such as 50 Hz to 70 Hz, then the automatic monitoring self-test fault test stops, but monitoring of GP3 continues. Thus, when a circuit interrupting device according to the present invention is connected to a variable power source (e.g., a portable generator) and the power source exhibits a lower frequency at startup and requires a stabilization period before achieving an optimal frequency (e.g., 60 Hz), premature or erroneous power fault determination can be avoided.

[0073] If the frequency is not stable at the optimal frequency, or at least not within an acceptable range, then the start of the automatic monitoring routine is delayed until the frequency stabilizes. If the frequency does not achieve the optimal frequency, or a frequency within an acceptable range within a predetermined time, then the failure score is incremented. Similar to the failure score discussed previously with respect to the automatic monitoring routine, if the score reaches a given threshold, then the microcontroller 301 declares EOL.

[0074] As described above, according to at least one exemplary embodiment, the programmable device 301 is implemented in a microcontroller. Because some microcontrollers include non-volatile memory, such as for storing various data in the event of a power outage, etc., according to yet another embodiment, all events, timers, scores, and / or states within the non-volatile memory are cleared after the device is powered on. Thus, if a failure score or other condition is generated due to improper device installation, insufficient or improper power, or some other non-critical condition with the circuit interrupting device itself, the failure score is reset after power-up when the score incrementing event may no longer exist. Another way to avoid this potential problem according to the present invention is to utilize a programmable device that does not include non-volatile memory.

[0075] Thus, the present invention provides, inter alia, a GFCI receptacle having one or more line contact arms and one or more load contact arms. The line contact arms each have upper phase and neutral line contacts positioned on a curved portion of the line contact arm, and lower phase and neutral line contacts positioned on a generally straight portion of the line contact arm. The load contact arms each have phase and neutral load contacts positioned on a curved portion of the load contact arm. Various features and advantages of the present invention are set forth in the following claims.

Claims

1. A wiring device, comprising: One or more line contact arms electrically connected to the line terminals, each line contact arm having: an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a generally straight portion of the line contact arm; as well as one or more load contact arms electrically connected to the load terminals, each load contact arm having a load contact positioned on a bent portion of the load contact arm, Wherein, when the wiring device is in the closed position, the surface contact and the upper line contact are electrically connected, and the lower line contact and the load contact are electrically connected; and when the wiring device is in the open position, the surface contact and the upper line contact are electrically disconnected, and the lower line contact and the load contact are electrically disconnected.

2. The wiring device of claim 1, wherein the face contact is substantially planarly connected to the upper line contact when the wiring device is in the closed position.

3. The wiring device of claim 1, wherein the lower line contact is substantially flatly connected to the load contact when the wiring device is in the closed position.

4. The wiring device of claim 1, wherein the bent portion of the circuit contact arm is bent at an angle of three to six degrees relative to the generally straight portion of the circuit contact arm. 5 . The wiring device according to claim 1 , wherein the bent portion of the load contact arm is bent at an angle of three to six degrees.

6. The wiring device of claim 1 , further comprising a fault detection circuit, wherein the fault detection circuit detects a fault condition in the wiring device and generates a fault detection signal when the fault condition is detected, wherein the fault detection signal electrically disconnects the face contact from the upper line contact and electrically disconnects the lower line contact from the load contact.

7. A wiring device, comprising: One or more line contact arms having: upper part a line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a generally straight portion of the line contact arm; as well as one or more load contact arms having load contacts positioned on a bent portion of the load contact arms, Wherein, when the wiring device is in the closed position, the surface contact and the upper line contact are electrically connected, and the lower line contact and the load contact are electrically connected; and when the wiring device is in the open position, the surface contact and the upper line contact are electrically disconnected, and the lower line contact and the load contact are electrically disconnected.

8. The wiring device of claim 7, further comprising a fault detection circuit that detects a fault condition in the wiring device and generates a fault detection signal when the fault condition is detected, wherein the fault detection signal electrically disconnects the face contact from the upper line contact and electrically disconnects the lower line contact from the load contact.

9. The wiring device according to claim 7, further comprising a surface terminal for electrically connecting to an external load, the surface terminal being electrically connected to the upper line contact; a line terminal for electrically connecting to an external power supply, the line terminal being electrically connected to the one or more line contact arms; as well as A load terminal is used to electrically connect to a second external load, wherein the load terminal is electrically connected to the one or more load contact arms.

10. The wiring device of claim 7, wherein the face contact is substantially planarly connected to the upper line contact when the wiring device is in the closed position.

11. The wiring device of claim 7, wherein the lower line contact is substantially flatly connected to the load contact when the wiring device is in the closed position.

12. The wiring device of claim 7, wherein the bent portion of the circuit contact arm is bent at an angle of three to six degrees relative to the generally straight portion of the circuit contact arm.

13. The wiring device according to claim 7, wherein the bent portion of the load contact arm is bent at an angle of three to six degrees.

14. A method of operating a wiring device, the method comprising: One or more circuit contact arms are provided, each circuit contact arm having an upper line contact positioned on a curved portion of the line contact arm, and a lower line contact positioned on a generally straight portion of the line contact arm; as well as One or more load contact arms are provided, each load contact arm having: a load contact positioned on a bent portion of the load contact arm, Wherein, when the wiring device is in the closed position, the surface contact and the upper line contact are electrically connected, and the lower line contact and the load contact are electrically connected; and when the wiring device is in the open position, the surface contact and the upper line contact are electrically disconnected, and the lower line contact and the load contact are electrically disconnected.

15. The method of claim 14, wherein the face contact is electrically connected to the upper line contact in a substantially planar connection.

16. The method of claim 14, wherein the lower line contact is electrically connected to the load contact in a substantially planar connection.

17. The method of claim 14, wherein the curved portion of the circuit contact arm is bent at an angle of three to six degrees relative to the generally straight portion of the circuit contact arm.

18. The method of claim 14, wherein the bent portion of the load contact arm is bent at an angle of three to six degrees.

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