Ground fault circuit interrupter (GFCI) apparatus, system and method

Abstract

A ground fault circuit interrupter (GFCI) may include a current transformer (CT) including a single core, a first winding wound around the single core, and a second winding wound around the single core. The GFCI may include a ground fault (GF) detection module operatively connected to the first winding to receive a signal from the first winding and configured to determine whether a line-to-ground fault exists. The GFCI may also include a GN excitation operatively connected to the second winding to provide a GN excitation signal to the second winding. The GFCI may also include a ground neutral (GN) detection module operatively connected to the second winding and configured to receive a signal from the second winding to determine if a neutral-to-ground fault exists.

Description

[0001] Cross - reference to related applications

[0002] This application is a continuation of non - provisional U.S. patent application No. 18 / 138,258, filed on April 24, 2023, and non - provisional U.S. patent application No. 18 / 101,060, filed on January 24, 2023, which claims the priority and benefit of U.S. provisional application No. 63 / 436,436, filed on December 30, 2022, the entire content of which is incorporated herein by reference in its entirety. Technical field

[0003] This disclosure relates to ground - fault circuit interrupters (GFCIs). Background art

[0004] Conventional ground - fault circuit interrupters (GFCIs) with ground - fault (GF) and ground - neutral (GN) detection have circuits for both GF and GN that utilize the same analog signal chain and current - transformer (CT) sense winding. This requires the control unit to control a field - effect transistor (FET) that switches the load impedance between two states to detect GF or GN, but not both simultaneously. Switching the FET can also introduce interference into the signal, which makes precise detection difficult. Additionally, in combination with a set of field conditions, this can cause the circuit breaker to trip unnecessarily in the field.

[0005] Such conventional methods and systems are generally considered satisfactory for their intended purposes. However, there is still a need in the art for improved GFCI devices, systems, and methods. This disclosure provides a solution to this need. Summary of the invention

[0006] A ground - fault circuit interrupter (GFCI) can include a current transformer (CT) that includes a single core, a first winding wound around the single core, and a second winding wound around the single core. The GFCI can include a ground - fault (GF) detection module operatively connected to the first winding to receive a signal from the first winding and configured to determine whether a line - to - ground fault exists. The GFCI can also include a GN excitation operatively connected to the second winding to provide a GN excitation signal to the second winding. The GFCI can further include a ground - neutral (GN) detection module operatively connected to the second winding and configured to receive a signal from the second winding to determine whether a neutral - to - ground fault exists. In certain embodiments, the GFCI can include a GF test - signal excitation operatively connected to the second winding to provide a test signal to the second winding when activated such that the test signal is received by the first winding.

[0007] According to at least one aspect of the present disclosure, a GFCI may include a CT that includes a single core, a GF sensing winding wound around the single core, and a test winding wound around the single core. The GFCI may include a GF detection module operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists. The GFCI may also include a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated such that the test signal is coupled to the GF sensing winding via the CT and detected by the GF detection module, which receives the signal from the GF sensing winding to determine whether the CT and the GF signal chain are operating correctly. The GFCI may also include a GN detection module operatively connected to at least one winding of the current transformer and configured to receive a signal from the at least one winding to determine whether a neutral-to-ground fault exists.

[0008] In some embodiments, at least one winding of the current transformer operatively connected to the GN detection module may be the test winding such that the GN detection module is configured to receive a signal from the test winding to determine whether a neutral-to-ground fault exists. In some embodiments, the GFCI may include a GN excitation operatively connected to the test winding to provide a GN excitation signal to the test winding. The GN excitation may be configured to allow the GN detection module to sense a change in impedance to determine whether a neutral-to-ground fault exists.

[0009] In some embodiments, the test signal excitation and the GN excitation are co-hosted. In some embodiments, the GF detection module and the GN detection module operate simultaneously and / or continuously.

[0010] In some embodiments, the GFCI may include a test detection module operatively connected to the GF sensing winding to receive a test signal from the test signal excitation to test the current transformer and / or the GF signal chain between the current transformer and the GF detection module. In some embodiments, the test detection module may be configured to receive a test start signal associated with the activated test signal excitation. In some embodiments, the GF detection module and the test detection module may be co-hosted.

[0011] In some embodiments, the current transformer may include a GN winding (e.g., separate from the test winding). In such embodiments, at least one winding of the current transformer operatively connected to the GN detection module is the GN winding.

[0012] According to at least one aspect of the present disclosure, a GFCI circuit breaker may be similar to and / or include any suitable embodiment and / or portion of the GFCI disclosed above. For example, the GFCI circuit breaker may include a line conductor passing through a single core and a neutral line passing through the single core.

[0013] According to at least one aspect of the present disclosure, a method may include using at least two coils on a single core to provide simultaneous GF monitoring and GN monitoring. In certain embodiments, using at least two coils may include using a GF sensing winding to sense line-to-ground faults and using a test winding to sense neutral-to-ground faults.

[0014] According to at least one aspect of the present disclosure, a GFCI may include a CT arrangement that includes one or more cores, a GF sensing winding wound around one of the one or more cores, and a test winding wound around one of the one or more cores. The GFCI may include a GF detection module, a test signal excitation and GN detection module, the GF detection module being operatively connected to the GF sensing winding to receive signals from the GF sensing winding and configured to determine whether a line-to-ground fault exists, the test signal excitation being operatively connected to the test winding to provide a test signal to the test winding when activated such that the test signal is coupled to the GF sensing winding via the CT and detected by the GF detection module, the GF detection module receiving signals from the GF sensing winding to determine whether the CT and the GF signal chain are operating correctly, the GN detection module being operatively connected to the test winding and configured to receive signals from the test winding to determine whether a neutral-to-ground fault exists. The GFCI may include a GN excitation operatively connected to the test winding to provide a GN excitation signal to the test winding. The GFCI may include any other components, e.g., as disclosed above, and / or may be similar to other embodiments of the GFCI disclosed herein. Any suitable number of cores is contemplated herein (e.g., one, more than one) (e.g., such that the GFCI includes any suitable number of CTs, e.g., one, two).

[0015] According to at least one aspect of the present disclosure, a GFCI circuit breaker may be or include a GFCI as described above. The GFCI circuit breaker may include a line conductor passing through one or more cores, and a neutral conductor passing through one or more cores. According to at least one aspect of the present disclosure, a method may include using a GF sensing winding to provide GF monitoring to detect line-to-ground faults, and using a test coil to test the GF monitoring function and provide GN monitoring to detect neutral-to-ground faults. In certain embodiments, the GN monitoring and the GF monitoring are simultaneous. The GFCI circuit breaker may be similar to and / or include any suitable embodiment and / or portion of the GFCI disclosed above.

[0016] According to at least one aspect of the present disclosure, a GFCI may include a first current transformer CT having a first core and a GF sensing winding. The first core may be a PCB core or an air core, and the GF sensing winding is wound around the first core (e.g., around the entire circumference). The GFCI may include a second CT having a second core and a GN sensing winding. The second core may be a ferromagnetic or nanocrystalline core, and the GN sensing winding is wound (e.g., partially) around the second core. The GFCI may include a GF detection module operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists. The GFCI may include a GN detection module operatively connected to the GN sensing winding and configured to receive a signal from the GN sensing winding to determine whether a neutral-to-ground fault exists.

[0017] In some embodiments, the first current transformer includes a test winding wound around the first core. In some embodiments, the GFCI includes a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated, such that the test signal is coupled to the GF sensing winding via the CT and detected by the GF detection module, which receives a signal from the GF sensing winding to determine whether the CT and the GF signal chain are operating correctly.

[0018] In some embodiments, the GN sensing winding is wound around the second core 20 times. In some embodiments, the GF sensing winding is wound around the entire circumference of the first core.

[0019] In some embodiments, the GN excitation is configured to allow the GN detection module to sense a change in impedance to determine whether a neutral-to-ground fault exists. In some embodiments, the GF detection module and the GN detection module operate simultaneously and / or continuously.

[0020] In some embodiments, the first CT may have a coreless planar PCB GF sensing winding instead of a core and a winding wound around the core. Any suitable number of planar windings is contemplated herein.

[0021] According to at least one aspect of the present disclosure, a GFCI circuit breaker may include the first CT and the second CT as described above. The GFCI circuit breaker may include line conductors passing through both the first core and the second core or both the coreless GF sensing winding and the second core. The GFCI circuit breaker may include neutral conductors passing through both the first core and the second core or both the coreless GF sensing winding and the second core. The GFCI circuit breaker may be similar to and / or include any suitable embodiment and / or portion of the GFCI disclosed above.

[0022] According to at least one aspect of the present disclosure, a ground fault circuit interrupter (GFCI) may include a current transformer (CT) having a single core, a first winding wound around the single core, and a test winding wound around the single core. The GFCI may include a ground fault (GF) detection module operatively connected to the first winding to receive a signal from the first winding and configured to determine whether a line-to-ground fault exists, a ground neutral (GN) detection module operatively connected to the first winding and configured to receive a signal from the first winding to determine whether a neutral-to-ground fault exists, a FET configured to switch between a GF sensing mode and a GN sensing mode, and a push-to-test module operatively connected to the test winding to inject a test signal onto the single core.

[0023] According to at least one aspect of the present disclosure, a method may include injecting a controller signal onto a test winding using a controller, receiving the controller signal from a sensing winding magnetically coupled to the test winding via a common core, and detecting the presence of the test signal at a test detection module. The controller may be activated by a push-to-test (PTT) button. The controller signal may have a preset characteristic configured to be recognized by the test detection module. The controller signal may be a square wave signal.

[0024] These and other features of embodiments of the present subject matter disclosure will become more apparent to those skilled in the art from the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Accordingly, those skilled in the art to which the present disclosure pertains will readily understand how to make and use the devices and methods of the present disclosure without undue experimentation. Embodiments thereof will be described in detail below with reference to certain drawings, wherein:

[0026] Figure 1A is a schematic diagram of an embodiment of a ground fault circuit interrupter (GFCI) according to the present disclosure;

[0027] Figure 1B is a schematic diagram of an embodiment of the GFCI of FIG. 1, shown with a hot wire and a neutral wire passing through a current transformer (CT);

[0028] Figure 2 is a schematic diagram of an embodiment of a GFCI according to the present disclosure;

[0029] Figure 3 is a schematic diagram of an embodiment of a GFCI according to the present disclosure;

[0030] Figure 4A is a schematic diagram of an embodiment of a GFCI according to the present disclosure;

[0031] Figure 4B is Figure 4ASchematic diagram of an embodiment of a portion of a GFCI, showing an example circuit representation;

[0032] Figure 4C is a schematic diagram showing an embodiment of a PCB and / or an air core circuit transformer;

[0033] Figure 4D is a schematic diagram of an embodiment of a planar coreless PCB GF sensing winding;

[0034] Figure 5A and 5B shows a schematic diagram of a simulation of one or more embodiments of the present disclosure; and

[0035] Figure 6 shows an embodiment of a test control scheme according to the present disclosure. Detailed Description

[0036] Reference will now be made to the accompanying drawings, in which like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, an illustrative view of an embodiment of a ground fault circuit interrupter (GFCI) according to the present disclosure is shown in Figure 1A and is generally designated by reference numeral 100. Other embodiments and / or aspects of the present disclosure are shown in Figures 1B - 5B .

[0037] Referring to Figure 1A and 1B , the ground fault circuit interrupter (GFCI) 100 may include a current transformer (CT) 103, which includes a single core 105 (e.g., a toroidal or ring-shaped body). The core 105 may be made of, for example, a ferromagnetic material and / or a nanocrystalline material.

[0038] The CT 103 may include a first winding 107 wound around the single core 105 (e.g., substantially uniformly around the entire circumference of the core 105), and a second winding 109 wound around the single core 105 (e.g., only around a portion of the circumference of the core 105). Any other suitable amount of winding (e.g., 360 degrees, 90 degrees, etc.) for either winding is contemplated herein to be performed according to the needs of the desired application.

[0039] The GFCI 100 may include a ground fault (GF) detection module 111 operatively connected to the first winding 107 to receive a signal from the first winding 107 and configured to determine whether a line-to-ground fault exists. For example, the first winding 107 may be configured to output a voltage indicative of a current difference between the line conductor 102 (e.g., which sends current to a load) and the neutral conductor 104 (e.g., which returns current from the load). When there is no line-to-ground fault, the equal and opposite currents in the line conductor 102 and the neutral conductor 104 substantially cancel the electromagnetic effects, and no voltage or a negligible voltage (e.g., due to winding or conductor placement defects) is induced on the first winding 107. If a line-to-ground fault exists (e.g., current travels from the line conductor 102 to ground), a threshold voltage may be induced on the first winding 107 because the current returning on the neutral conductor 104 is less than the current in the line conductor 102. Thus, the GF detection module 111 may be configured to detect whether the voltage from the first winding 107 is higher than a threshold to determine whether a ground fault exists.

[0040] The GFCI 100 may also include a GN excitation 113 operatively connected to the second winding 109 to provide a GN excitation signal to the second winding 109. The GFCI 100 may also include a ground neutral (GN) detection module 115 operatively connected to the second winding 109 and configured to receive a signal from the second winding 109 to determine whether a neutral-to-ground fault exists. For example, the GN excitation signal may be time-varying and allow the GN detection module 115 to sense impedance changes in the system, e.g., which may indicate a ground neutral fault (e.g., when the neutral conductor 104 is grounded, it may not exist as a current difference between the line conductor 102 and the neutral conductor 104). In some embodiments, the GFCI 100 may include a GF test signal excitation ( Figure 1A not shown, e.g., Figure 2 the excitation 219 shown) operatively connected to the second winding 109 to provide a test signal to the second winding 109 when activated such that the test signal is received by the first winding 107. One or more embodiments of the GFCI as disclosed herein (e.g., each as disclosed herein) may be configured to simultaneously monitor GF and GN and may also provide a GF test (e.g., for testing the functionality of any part of the GFCI and / or the GF signal chain 117).

[0041] According to at least one aspect of the present disclosure, referring to Figure 2 the GFCI 200 may include a CT 203 (e.g., similar to CT103), the CT 203 including a single core 205 (e.g., similar to Figure 1BThe core shown is 105). CT 203 may include a GF sensing winding 207 (e.g., similar to the first winding 107) wound around a single core 205. CT 203 may include a test winding 209 (e.g., similar to the second winding 109) wound around a single core 205. The GFCI 200 may include a GF detection module 211 that is operatively connected to the GF sensing winding 207 (e.g., via a GF signal chain 217) to receive signals from the GF sensing winding 207 and is configured to determine whether a line-to-ground fault exists (e.g., similar to module 111).

[0042] The GFCI 200 may also include a test signal excitation 219, i.e., a push-to-test (PTT) excitation, which is operatively connected to the test winding 209 to provide a test signal to the test winding 209 when activated, such that the test signal is coupled to the GF sensing winding via the CT and detected by the GF detection module, which receives signals from the GF sensing winding to determine whether the CT and the GF signal chain are operating correctly 207 (e.g., via electromagnetic interaction). For example, the test signal excitation 219 may be configured to output a test signal having identifiable characteristics (e.g., amplitude, frequency, etc.), which may be preset and / or controllable in real time.

[0043] The GFCI 200 may also include a GN detection module 215 (e.g., similar to module 115), which is operatively connected to at least one winding of the current transformer 203 (e.g., the test winding 209) and is configured to receive signals from the at least one winding (e.g., the test winding 209) to determine whether a neutral-to-ground fault exists. In some embodiments, the at least one winding of the current transformer 203 that is operatively connected to the GN detection module 215 may be the test winding 209, e.g., as Figure 2 shown, such that the GN detection module 215 is configured to receive signals from the test winding 209 to determine whether a neutral-to-ground fault exists. In some embodiments, the GFCI 200 may include a GN excitation 213 (e.g., similar to the GN excitation 113) operatively connected to the test winding 209 to provide a GN excitation signal to the test winding 209. The GN excitation 213 may be configured to allow the GN detection module 215 to sense a change in impedance (e.g., in conductors 102, 104) to determine whether a neutral-to-ground fault exists.

[0044] In some embodiments, as Figure 2As shown, the test signal excitation 219 (e.g., push-to-test (PTT) excitation) and the GN excitation 213 are co-hosted (e.g., on a single module 221 of hardware and / or software). In some embodiments, the GN excitation 213 and the test excitation 219 may be hosted separately. In some embodiments, the test signal excitation 219 is not required for the primary inductive test signal.

[0045] In some embodiments, the GF detection module 211 and the GN detection module 215 operate simultaneously and / or continuously. In this regard, the GFCI 200 can always monitor both GN faults and GF faults without having to utilize and switch hardware and control logic.

[0046] In some embodiments, the GFCI 200 may include a test detection module 223 operatively connected to the GF sensing winding 207 to receive a test signal from the test signal excitation 219 (through the CT 203 and any GF signal chain 217) to test the current transformer 203 and / or the GF signal chain 217 between the current transformer 203 and the GF detection module 211. In some embodiments, the test detection module 223 may be configured to receive a test start signal associated with the activated test signal excitation. In some embodiments, there may be no direct connection between the test detection module 223 and the test signal excitation 219 (e.g., and the test detection module 223 may be configured to identify one or more prescribed test signals from the test signal excitation 219). In some embodiments, the GF detection module 211 and the test detection module 223 may be co-hosted, e.g., as Figure 2 shown.

[0047] In some embodiments, referring to Figure 3 , the GFCI 300 may include a current transformer 303. The current transformer 303 may include a GN winding 323 (e.g., separate from the test winding 209), which is, for example, wound around a single core 205 (e.g., at least part of the circumference of the core 205). In such an embodiment, at least one winding of the current transformer 303 operatively connected to the GN detection module 215 is the GN winding 323. In this regard, each function may have an independent path. As shown, in some embodiments, the test signal excitation 219 may be separated from the GN excitation 213. The GFCI 300 may be otherwise similar to the GFCI 200 disclosed herein.

[0048] Embodiments of the GFCI disclosed herein (e.g., GFCI 100, 200, 300) can be used in any suitable application (e.g., outlet, circuit breaker). According to at least one aspect of the present disclosure, a GFCI circuit breaker (not shown, e.g., single pole, double pole, or any other suitable circuit breaker type) can be similar to and / or include any suitable embodiment and / or portion of the GFCI 100, 200, 300 disclosed above. The GFCI circuit breaker can include, for example, line conductors 102 passing through a single core 105, 205 and neutral conductors 104 passing through the single core 105, 205.

[0049] According to at least one aspect of the present disclosure, a method can include using at least two coils (e.g., a first winding 107 and a second winding 109, a GF sensing winding 207 and a test winding 209, or three windings 207, 209, and 323) on a single core 303 to provide simultaneous GF monitoring and GN monitoring. In certain embodiments, using at least two coils can include using a GF sensing winding 207 to sense a line-to-ground fault and using a test winding 209 to sense a neutral-to-ground fault.

[0050] According to at least one aspect of the present disclosure, referring to Figure 4A and 4B , the GFCI 400 can include a first current transformer CT 403a having a first core 405a. The first core 405a can be a PCB core or an air core (e.g., as Figure 4C shown). The GFCI 400 can include a GF sensing winding 207 (e.g., similar to the windings 107, 207 described above) wound around the first core 405a (e.g., around the entire circumference).

[0051] The GFCI 400 can include a second CT 403b having a second core 405b (separate from the first core 403a). The second core 405b can be a ferromagnetic or nanocrystalline core. The GFCI 400 can include (e.g., partially) a GN sensing winding wound around the second core. The GFCI can include a GF detection module 211 (e.g., as described above), the GF detection module being operatively connected to the GF sensing winding 207 to receive a signal from the GF sensing winding 207 and configured to determine whether a line-to-ground fault exists. The GFCI 400 can include a GN detection module 215 (e.g., as described above), which is operatively connected to the GN sensing winding 323 and configured to receive a signal from the GN sensing winding 323 to determine whether a neutral-to-ground fault exists.

[0052] In some embodiments, the first current transformer 403a may include a test winding 209 (e.g., as described above) wound around a first core 403a (e.g., wound or planar wound). In some embodiments, the GFCI 400 includes a test signal excitation 219 (e.g., as described above) operatively connected to the test winding 209 to provide a test signal to the test winding 209 when activated such that the test signal is coupled to the GF sense winding via the CT and detected by the GF detection module, which receives signals from the GF sense winding to determine if the CT and GF signal chains are operating correctly.

[0053] In some embodiments, the GN sense winding 323 is wound around the second core 20 times (e.g., only along a portion of the circumference, e.g., less than one-third of the circumference). In some embodiments, the GF sense winding is wound around the entire circumference of the first core. In some embodiments, the GN excitation 213 is configured to allow the GN detection module 215 to sense a change in impedance to determine if a neutral-to-earth fault exists (e.g., as described above). In some embodiments, the GF detection module 211 and the GN detection module 223 operate simultaneously and / or continuously (e.g., as described above).

[0054] In some embodiments, the first CT 403a may have a coreless planar PCB GF sense winding (e.g., as Figure 4D shown), rather than having a core 405a and a winding wound around the core 405a. Any suitable number of planar windings is contemplated herein.

[0055] Figure 5A and 5B FIG. shows a schematic diagram of a simulation of one or more embodiments of the present disclosure. Figure 5A FIG. shows a simulated circuit diagram, Figure 5B FIG. shows a charging result. As shown, with a 20-turn test winding, sufficient variation can be seen to detect a GN fault. Since the response difference is approximately 200 mVpp compared to when there is no GN fault, a GN fault of 2 Ω can be detected. This shows that the 20-turn test winding works when tested in isolation (e.g., as in the Figure 4A embodiment).

[0056] According to at least one aspect of the present disclosure, a GFCI circuit breaker (not shown) may include the first CT 403a and the second CT 403b as described above. The GFCI circuit breaker may include line conductor 102 passing through both the first core 405a and the second core 405b or both the coreless GF sensing winding 207 and the second core 209. The GFCI circuit breaker may include neutral conductor 104 passing through both the first core 405a and the second core 405b or both the coreless GF sensing winding 207 and the second core 405b. The GFCI circuit breaker may be similar to and / or include any suitable embodiment and / or portion of the GFCI disclosed above.

[0057] According to at least one aspect of the present disclosure, a GFCI (e.g., GFCI 100, 200, 300, 400) may include a CT arrangement (e.g., a single CT 103, 203, 303 or multiple CTs 403a, 403b as disclosed above) having one or more cores (e.g., a single core 105, 205 or cores 405a and 405b). The CT arrangement may include a GF sensing winding (e.g., as described above) wound around one of the one or more cores, and a test winding (e.g., as described above) wound around one of the one or more cores. The GFCI may include a GF detection module (e.g., as described above) operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists. The GFCI may further include a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated such that the test signal is coupled to the GF sensing winding via the CT and detected by the GF detection module, and the GF detection module receives the signal from the GF sensing winding to determine whether the CT and the GF signal chain are operating correctly. The GFCI may include a GN detection module operatively connected to the test winding and configured to receive a signal from the test winding to determine whether a neutral-to-ground fault exists. The GFCI may further include a GN excitation operatively connected to the test winding to provide a GN excitation signal to the test winding. The GFCI may include any other components, e.g., as disclosed above, and / or may be similar to other embodiments of the GFCI disclosed herein. Any suitable number of cores (e.g., one, more than one) is contemplated herein (e.g., such that the GFCI includes any suitable number of CTs, e.g., one, two).

[0058] According to at least one aspect of the present disclosure, a GFCI circuit breaker may be or include the GFCI as described above. The GFCI circuit breaker may include line conductor 102 passing through one or more cores and neutral conductor 104 passing through one or more cores.

[0059] According to at least one aspect of the present disclosure, a method may include using a GF sensing winding to provide GF monitoring to detect line-to-ground faults, and using a test coil to test the GF monitoring function and provide GN monitoring to detect neutral-to-ground faults. In certain embodiments, the GN monitoring and the GF monitoring are simultaneous. The GFCI breaker may be similar to and / or include any suitable embodiments and / or portions of the GFCIs (e.g., GFCI 100, 200, 300, 400) disclosed above.

[0060] According to at least one aspect of the present disclosure, a ground fault circuit interrupter (GFCI) may include a current transformer (CT) having a single core, a first winding wound around the single core, and a test winding wound around the single core. The GFCI may include a ground fault (GF) detection module operatively connected to the first winding to receive a signal from the first winding and configured to determine whether a line-to-ground fault exists, a ground neutral (GN) detection module operatively connected to the first winding and configured to receive a signal from the first winding to determine whether a neutral-to-ground fault exists, a FET configured to switch between a GF sensing mode and a GN sensing mode, and a push test module operatively connected to the test winding to inject a test signal onto the single core.

[0061] Figure 6 An embodiment of a test control scheme according to the present disclosure is shown. According to at least one aspect of the present disclosure, referring Figure 6 to, for example, a method may include injecting a controller signal onto the test winding using a controller (e.g., a microprocessor, a microcontroller, or any other suitable logic device), receiving the controller signal from a sensing winding magnetically coupled to the test winding via a common core, and detecting the presence of the test signal at a test detection module. The controller may be activated by a push to test (PTT) button. The controller signal may have a preset characteristic configured to be recognized by the test detection module. The controller signal may be a square wave signal or any other waveform generated by a digital-to-analog converter of the controller and / or any other analog circuit associated therewith. Embodiments of the method may enable the use of a capacitive touch PTT button instead of using a conventional momentary switch PTT button. The conventional momentary switch PTT button is used to close a physical circuit and send a half-wave rectified 50 Hz or 60 Hz signal, which can only be detected during a short window (e.g., 30% of the time). Embodiments may allow the injected excitation signal to have any arbitrary shape or frequency to avoid constructive / destructive interference with existing leakage current couplings onto the GF sensing winding, to better prevent false negatives and false positives in both GF detection and PTT fault mode detection during the PTT process.

[0062] Embodiments may also allow buttons on the circuit breaker to be used for status and / or history checks without creating a GF leakage. For example, the controller can detect the length and / or pattern of the PTT button / signal and determine whether to send a test signal or take another action (e.g., provide status and / or history checks by a short press). Any other suitable logic for button functionality is envisioned herein. Embodiments may allow PTT detection for 100% of the injection time since the controller can control, for example, the signal type, characteristics, and / or when the signal starts and stops.

[0063] According to the present disclosure, certain embodiments may enable the use of a second winding on a ground fault sensor to detect a grounded neutral fault. Certain embodiments may utilize a separate analog signal chain to use an additional winding added to an existing ground fault current transformer to detect a grounded neutral fault. By separating the two signal chains, this deviates from current systems. Embodiments may achieve a minimal increase in part count.

[0064] Existing systems with ground fault and grounded neutral detection circuits utilize the same analog signal chain. The switching between the two states (GF sensing and GN sensing) combined with a set of field conditions makes it possible for the circuit breaker to trip unnecessarily in the field. By separating the functionality into two different signal chains, the field performance and stability of the device can be improved without additional cost.

[0065] Compared to traditional systems, embodiments of the grounded neutral detection architecture may include new hardware designs, frequency range changes, and various firmware algorithm changes. Embodiments may provide separate GF and GN signal chains for more robust GF and GN detection using multiple windings. Embodiments eliminate field effect transistors (FETs) and enable simultaneous sampling of GN signals and GF signals.

[0066] Embodiments include alternative methods for separating GF and GN signal chains. For example, certain embodiments include two or more windings on a common core. Embodiments may utilize more robust detection to reduce nuisance tripping, provide simultaneous sampling on separate ADC channels for GF and GN, eliminate distortion from burden FET switching, thus giving more accurate data, and may extend the GF trip time to 1486% by utilizing an estimate of the GN level (e.g., the 40 mA GF trip time increases from 25 ms to 371 ms). Such embodiments may use the same PCBA footprint while the total BOM cost only increases slightly.

[0067] In some embodiments, GF and GN sensing can have completely separate lanes. For example, GF sensing can use an air-core (e.g., a coreless planar printed circuit board transformer) CT, and GN sensing can use a ferrite or nanocrystalline core CT. Such embodiments can include the same advantages as described above for the single-core embodiments and also prevent the GF CT from saturating during a large fault, which allows the GF detection module to have a more robust detection logic for nuisance trips. Embodiments can also utilize 20 turns or less (e.g., 1 turn, 5 turns, 10 turns, etc.) on the GN CT, which can be less expensive than currently used components to offset the cost of adding the air-core / PCB coil.

[0068] All embodiments can utilize a push-button test system. All embodiments can be compatible with a primary injection architecture and / or a secondary injection architecture.

[0069] As described above, some embodiments can include two windings on a shared core. The core is configured to be magnetically connected to the line conductor and the neutral conductor such that the line conductor and the neutral conductor can induce a current in the windings that is proportional to the current in the core. Each winding can be an enamel-coated copper wire. In an embodiment, the ground fault module can be configured to open the contactor if the detected fault is large enough for a long enough time. Some embodiments can be configured to account for interference from other windings on the common core. The GF test signal can have different signals / waveforms to make it easier to filter out background noise. Embodiments can combine the test winding and the GN sensing winding into one CT. Some embodiments can combine GN excitation hardware and GF test excitation hardware (e.g., the same microchip can be configured to emit different kinds of signals to perform both functions). In some embodiments, the co-hosted test functions can have to be done at different times. In some embodiments, both can be done simultaneously.

[0070] Embodiments of the GN detection module can be configured to sense impedance changes by varying the GN excitation signal. For example, the GN detection module can include a microcontroller that injects a high excitation signal or a low excitation signal back and forth into the windings and into the core.

[0071] Some embodiments may include three windings on a shared core. In such embodiments, the GN function can be decoupled from the test function. This can be a way to separate each function and make them operate independently. In this case, there can be more pins because there are separate paths, more windings, and additional hardware. However, each path can be tuned to the optimal operation of that path. For example, the purpose of the test winding is to inject a test signal onto the GF signal chain to see if everything is working properly, and the GN detection signal on the GF chain may not necessarily be desirable. In some embodiments, the GN signal should be detectable but negligible. For example, being able to tune each signal variation individually can allow for the desired tuning of the GN excitation signal and the PTT test signal.

[0072] Some embodiments may include a fully separated GF CT and GN CT to further separate the paths. Such embodiments have two current transformers. In some embodiments, the GF side may have a PCB transformer with two windings (e.g., sensing and testing), and the GN side may have a ferromagnetic core (e.g., ferrite or single crystal). For example, the traces in the PCB can form the windings. This works because the weaker signal of the GF test signal is acceptable, but GN detection may require a stronger signal to function.

[0073] Embodiments may include any suitable signal conditioning components. The automatic monitoring requirements of UL943 can be met by primary current injection or secondary connection, and for example, both are compatible with each embodiment.

[0074] Embodiments may include up to three windings, one for GF, one for GN, and one for an automatic monitor (e.g., GF test excitation) on a shared core. Embodiments may include up to two windings on an air core (i.e., no core) CT, one for GF and one for the automatic monitor. Embodiments allow for simultaneous data sampling of GF and GN, the use of an air core transformer or a coreless planar PCB transformer for GF, and secondary connection signal injection for the automatic monitor.

[0075] Embodiments may include multiple windings on a shared core that separate GF and GN signals to reduce interference and increase robustness while minimizing BOM cost and PCB footprint / real - estate. Embodiments allow for simultaneous data sampling of GF and GN signals. In cases where the GN condition is weak or non - existent, embodiments can further extend the required trip time of the GFCI (e.g., up to 1486% in the absence of the GN condition), thereby reducing the risk of nuisance tripping. By eliminating the need for GN detection interrupts, simultaneous data sampling nearly doubles the amount of data used in the portion of the GF test that requires the fastest trip time. Simultaneous data sampling also allows GN detection to occur continuously rather than only for 5 ms at 300 ms intervals, thus increasing the robustness of GN detection and reducing the risk of nuisance tripping on high - frequency leakage current noise.

[0076] Embodiments may include any suitable computer hardware and / or software modules to perform any suitable functions (e.g., as disclosed herein). Any suitable modules and / or incentives disclosed herein may include any suitable hardware and / or software modules.

[0077] As will be understood by those skilled in the art, aspects of the present disclosure may be embodied as a system, method, or computer program product. Accordingly, aspects of the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which possibilities may be referred to herein as a "circuit", "module", or "system". A "circuit", "module", or "system" may include one or more portions of one or more separate physical hardware and / or software components that can together perform the disclosed functions of the "circuit", "module", or "system", or a "circuit", "module", or "system" may be a single self - contained unit (e.g., of hardware and / or software). Additionally, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer - readable media having computer - readable program code embodied thereon.

[0078] Any combination of one or more computer-readable media can be utilized. A computer-readable medium can be either a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium can be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0079] A computer-readable signal medium can include a propagated data signal that contains computer-readable program code, for example, in a baseband or as part of a carrier wave. Such a propagated signal can take any of a variety of forms, including but not limited to electromagnetic, optical, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium that is not a computer-readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0080] The program code embodied on the computer-readable medium can be transmitted using any appropriate medium, including but not limited to wireless, wireline, fiber optic cable, RF, etc., or any suitable combination of the foregoing.

[0081] The computer program code for performing the operations of the aspects of the present disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" programming language or similar programming languages. The program code can execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the latter case, the remote computer can be connected to the user's computer through any type of network connection, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., through the Internet using an Internet service provider).

[0082] Aspects of the present disclosure may be described with reference to the flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block of any flowchart and / or block diagram, and combinations of blocks in any flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing apparatus create means for implementing the functions / acts specified in one or more blocks of any flowchart and / or block diagram.

[0083] These computer program instructions may also be stored in a computer-readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions for implementing the functions / acts specified in one or more blocks of the flowchart and / or block diagram.

[0084] The computer program instructions may also be loaded onto a computer, other programmable data processing device, or other apparatus to cause a series of operational steps to be performed on the computer, other programmable device, or other apparatus to produce a computer-implemented process, such that the instructions executed on the computer or other programmable device provide a process for implementing the functions / acts specified herein.

[0085] Those of ordinary skill in the art will understand that any numerical values disclosed herein may be exact values or values within a range. Additionally, any approximation terms used in the present disclosure (e.g., "about", "approximately", "substantially") may represent the value within the range. For example, in some embodiments, the range may be within (plus or minus) 20%, or within 10%, or within 5%, or within 2%, or within any other suitable percentage or number understood by those of ordinary skill in the art (e.g., for known tolerance limits or error ranges).

[0086] Unless the context clearly dictates otherwise, the articles "a", "an", and "the" as used herein and in the appended claims are used herein to refer to one or more than one (i.e., at least one) grammatical object of the article. By way of example, "an element" means one element or more than one element.

[0087] As used herein in the specification and claims, the phrase "and / or" shall be understood to mean "any one or both" of the elements so combined, i.e., elements that are present together in some cases and separate in other cases. Multiple elements listed with "and / or" should be construed in the same manner, i.e., "one or more" of the elements so combined. Other elements may optionally be present in addition to those specifically identified by the "and / or" clause, whether related or unrelated to those specifically identified. Thus, as a non-limiting example, when used in conjunction with open-ended language such as "comprising," a reference to "A and / or B" may, in one embodiment, refer only to A (optionally including elements other than B); in another embodiment, only to B (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); and so on.

[0088] As used herein in the specification and claims, "or" shall be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted inclusively, i.e., including at least one of a plurality of elements or list of elements, but also including more than one, and optionally including additional unlisted items. Only terms that explicitly indicate the contrary, such as "only one of... " or "exactly one of...," or when used in a claim, "consisting of... " shall refer to including exactly one element of a plurality of elements or list of elements. In general, the term "or" as used herein shall only be interpreted to indicate exclusive alternatives (i.e., "one or the other but not both") when preceded by an exclusive term (e.g., "any one," "one of...," "only one of...," or "exactly one of...").

[0089] As would be understood by one of ordinary skill in the art in light of the present disclosure, any suitable combination of any disclosed embodiment and / or any suitable portion(s) thereof is contemplated herein.

[0090] The embodiments of the present disclosure described above and shown in the figures provide improvements in their respective fields. While the subject disclosure includes references to certain embodiments, those skilled in the art will readily appreciate that changes and / or modifications can be made thereto without departing from the spirit and scope of the subject disclosure.

Claims

1. A Ground Fault Circuit Interrupter (GFCI), comprising: A first Current Transformer (CT), comprising: A first core, wherein the first core is a PCB core or an air core; and A Ground Fault (GF) sensing winding wound around the first core; A second Current Transformer (CT), comprising: A second core, wherein the second core is a ferromagnetic or nanocrystalline core; and A Grounded Neutral (GN) sensing winding wound around the second core; A GF detection module operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists; and A GN detection module operatively connected to the GN sensing winding and configured to receive a signal from the GN sensing winding to determine whether a neutral-to-ground fault exists.

2. The GFCI according to claim 1, wherein, The first Current Transformer includes a test winding wound around the first core.

3. The GFCI according to claim 2, further comprising a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated, such that the test signal is received by the GF sensing winding.

4. The GFCI according to claim 3, wherein The GN sensing winding is wound around the second core more than once.

5. The GFCI according to claim 4, wherein, The GF sensing winding is wound around the entire circumference of the first core.

6. The GFCI according to claim 1, wherein, The GN excitation is configured to allow the GN detection module to sense a change in impedance to determine whether a neutral-to-ground fault exists.

7. The GFCI according to claim 1, wherein, The GF detection module and the GN detection module operate simultaneously and / or continuously.

8. A Ground Fault Circuit Interrupter (GFCI), comprising: A first Current Transformer (CT), comprising: A coreless planar PCB Ground Fault (GF) sensing winding; A second Current Transformer (CT), comprising: A second core, wherein the second core is a ferromagnetic or nanocrystalline core; and A Grounded Neutral (GN) sensing winding wound around the second core; A GF detection module operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists; and A GN detection module operatively connected to the GN sensing winding and configured to receive a signal from the GN sensing winding to determine whether a neutral-to-ground fault exists.

9. The GFCI according to claim 8, wherein, The first Current Transformer includes a test winding wound around the first core.

10. The GFCI according to claim 9, further comprising a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated, such that the test signal is received by the GF sensing winding.

11. The GFCI according to claim 10, wherein, The GN sensing winding is wound around the second core 20 times.

12. The GFCI according to claim 11, wherein, The GF sensing winding is wound around the entire circumference of the first core.

13. The GFCI according to claim 8, wherein, The GN excitation is configured to allow the GN detection module to sense a change in impedance to determine whether a neutral-to-ground fault exists.

14. The GFCI according to claim 9, wherein, The GF detection module and the GN detection module operate simultaneously and / or continuously.

15. A Ground Fault Circuit Interrupter (GFCI) circuit breaker, comprising: A first Current Transformer (CT), comprising: A first core, wherein the first core is a PCB core or an air core; and A ground fault (GF) sensing winding wound around the first core; A second current transformer (CT) comprising: A second core, wherein the second core is a ferromagnetic or nanocrystalline core; and A ground neutral (GN) sensing winding wound around the second core; A line conductor passing through both the first core and the second core; A neutral conductor passing through both the first core and the second core; A GF detection module operatively connected to the GF sensing winding to receive a signal from the GF sensing winding and configured to determine whether a line-to-ground fault exists; and A GN detection module operatively connected to the GN sensing winding and configured to receive a signal from the GN sensing winding to determine whether a neutral-to-ground fault exists.

16. The GFCI according to claim 15, wherein, The first current transformer includes a test winding wound around the first core.

17. The GFCI according to claim 16, further comprising a test signal excitation operatively connected to the test winding to provide a test signal to the test winding when activated such that the test signal is received by the GF sensing winding.

18. The GFCI according to claim 17, wherein, The GN sensing winding is wound around the second core 20 times.

19. The GFCI according to claim 18, wherein, The GF sensing winding is wound around the entire circumference of the first core.

20. The GFCI according to claim 15, wherein, The GN excitation is configured to allow the GN detection module to sense a change in impedance to determine whether a neutral-to-ground fault exists.

21. A method comprising: Injecting a controller signal onto a test winding using a controller; Receiving the controller signal from a sensing winding magnetically coupled to the test winding via a common core; and Detecting the presence of the test signal at a test detection module.

22. The method according to claim 21, wherein The controller is activated by a push-to-test (PTT) button.

23. The method according to claim 21, wherein, The controller signal has a preset characteristic configured to be recognized by the test detection module.

24. The method according to claim 23, wherein The controller signal is a square wave signal.

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