Ground fault interrupt for HVAC equipment outlet disconnect

Abstract

Systems and methods for providing ground fault detection in HVAC and other types of equipment allow for appropriate or safe levels of leakage current from the ground conductor of the equipment while providing discharge current protection for the branch circuit conductors that feed the equipment. In some embodiments, the systems and methods herein are implemented in the form of a ground fault interrupt system that is specifically designed to operate outdoors and can be installed at an equipment outlet disconnect device, which is typically installed on an exterior wall near the equipment. In some embodiments, the ground fault interrupt system incorporates the outlet disconnect device therein. In either case, the ability of the ground fault interrupt system to be located near the outdoor equipment allows technicians to more easily install, access, and repair the ground fault interrupt system compared to indoor arrangements.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This patent application claims priority to U.S. Provisional Application No. 63 / 541,722, filed on September 29, 2023 (entitled “Ground Fault Interrupt for HVAC Equipment Outlet Disconnect”), and is incorporated herein by reference. Technical Field

[0003] Embodiments of the present invention relate to heating, ventilation, and air conditioning (HVAC) systems, and more particularly, to systems and methods for improving ground fault detection in such systems. Background Art

[0004] Modern HVAC systems use variable speed drives and electronically controlled motors to maximize efficiency. Variable speed drives are used to adjust the speed of the compressor and / or motor that rotates the external HVAC fan unit to move air through the system. A disadvantage of these variable speed drive systems is the increase in electrical noise on the supply lines generated by the high frequency switching required to drive the motor. Noise filtering components can be added to HVAC equipment to mitigate high frequency electrical noise, but these components can cause leakage current to flow through the grounded conductor of the supply line. The leakage current flowing through the grounded conductor may be at line frequency and / or higher switching frequencies and may exceed the generally accepted ground fault current threshold of the GFCI circuit breaker at the distribution panel in magnitude, which can result in frequent tripping of the GFCI circuit breaker. In short, HVAC equipment is currently allowed to generate leakage current levels that are above the ground fault current threshold of existing GFCI circuit breakers installed at distribution panels, outlets, or circuit breakers. Summary of the invention

[0005] Embodiments of the present invention relate to systems and methods for improving ground fault detection in HVAC equipment and other types of equipment and appliances. The systems and methods provide an improved method of ground fault detection for such equipment that is capable of adapting to appropriate or safe levels of leakage current from the grounding conductor of the equipment while providing let-go current protection for the branch circuit conductors that power the equipment. In some embodiments, the systems and methods herein are implemented in the form of a ground fault interrupt system that is specifically designed to operate outdoors and can be installed at an equipment outlet disconnect device that is typically mounted on an exterior wall. In some embodiments, the ground fault interrupt system incorporates an outlet disconnect device therein. The ability of the ground fault interrupt system to be located near the outdoor equipment allows technicians to more easily install, access, and repair the ground fault interrupt system compared to indoor arrangements.

[0006] In general, on the one hand, embodiments of the present disclosure relate to a ground fault monitoring and detection system. The system particularly includes a current interruption switch configured to be connected to a power supply line. The system also includes a first leakage sensor connected to the current interruption switch, the first leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a first current threshold, the current interruption switch is controlled to interrupt the current through the power supply line. The system also includes a second leakage sensor connected to the current interruption switch, the second leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a second current threshold, the current interruption switch is controlled to interrupt the current through the power supply line. In one embodiment, the first current threshold is a release current, and the second current threshold is a predetermined amount greater than the release current.

[0007] In general, in another aspect, embodiments of the present invention relate to a method for providing ground fault monitoring and detection. The method particularly includes providing a current interruption switch configured to be connected to a power supply line. The method also includes connecting a first leakage sensor to the current interruption switch, the first leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a first current threshold, controlling the current interruption switch to interrupt the current flowing through the power supply line. The method also includes connecting a second leakage sensor to the current interruption switch, the second leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a second current threshold, controlling the current interruption switch to interrupt the current flowing through the power supply line. In one embodiment, the first current threshold is a release current, and the second current threshold is greater than the release current by a predetermined amount.

[0008] In general, on the other hand, embodiments of the present disclosure relate to a heating, ventilation, and air conditioning (HVAC) system. The HVAC system includes a distribution board, a power supply line connected to the distribution board, an HVAC device connected to the power supply line, and a current interruption switch connected to the power supply line between the distribution board and the HVAC device. The system also includes a first leakage sensor connected to the current interruption switch, the first leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a first current threshold, the current interruption switch is controlled to interrupt the current to the HVAC device. The system also includes a second leakage sensor connected to the current interruption switch, the second leakage sensor configured to detect a leakage current in the power supply line, and if the leakage current exceeds a second current threshold, the current interruption switch is controlled to interrupt the current to the HVAC device. In one embodiment, the first current threshold is a release current, and the second current threshold is greater than the release current by a predetermined amount.

[0009] According to any one or more of the aforementioned embodiments, the first leakage sensor includes a first ground fault interrupting device (GFID) connected to the first current sensor, and the second leakage sensor includes a second GFID connected to the second current sensor.

[0010] According to any one or more of the aforementioned embodiments, the power supply line includes a first ungrounded conductor, a second ungrounded conductor and a grounded conductor, the second leakage sensor is configured to detect a leakage current via the first and second ungrounded conductors, and the first leakage sensor is configured to detect a leakage current via the first and second ungrounded conductors and the grounded conductor.

[0011] According to any one or more of the aforementioned embodiments, the current interruption switch is a load-side current interruption switch, and the system further comprises a line-side current interruption switch configured to be connected to a power supply line.

[0012] According to any one or more of the aforementioned embodiments, the supervisory controller is connected to the line-side current interruption switch, and the supervisory controller is configured to control the line-side current interruption switch to interrupt the current through the power supply line when a predefined current interruption event occurs.

[0013] According to any one or more of the aforementioned embodiments, the local disconnect handle is mechanically connected to the line-side current interruption switch, and the local disconnect handle is configured to be operated by a user to manually interrupt the current through the power supply line.

[0014] According to any one or more of the aforementioned embodiments, the housing is configured to enclose the current interrupt switch and the first and second leakage sensors, and the housing provides weather protection for the current interrupt switch and the first and second leakage sensors.

[0015] According to any one or more of the foregoing embodiments, the supervisory controller is coupled to the first and second leakage sensors, the supervisory controller being configured to diagnose leakage currents detected by the first and second leakage sensors and provide status and diagnostic information to a user. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The foregoing and other advantages of the disclosed embodiments will become apparent upon reading the following detailed description and referring to the accompanying drawings, in which:

[0017] Figure 1 shows a high level view of an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention;

[0018] Figure 2 A circuit diagram of an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention is shown;

[0019] Figure 3 shows leakage current in an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention;

[0020] Figure 4shows another leakage current in an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention;

[0021] Figure 5 Another leakage current in an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention is shown, wherein the ground conductor is disconnected;

[0022] Figure 6 shows how to handle an ungrounded open conductor in an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention;

[0023] Figure 7 An exemplary method that may be used in an exemplary system equipped with a ground fault interruption system according to an embodiment of the present invention is shown;

[0024] Figure 8 is a functional block diagram of a general purpose computer system that may be used to implement various embodiments of the present invention; and

[0025] Fig. 9 is a functional block diagram of a general storage system that can be used to implement various embodiments of the present invention. DETAILED DESCRIPTION

[0026] The features and other details of the concepts, systems and techniques for which protection is sought herein will now be described in more detail. It should be understood that any specific embodiments described herein are shown by way of illustration, rather than as limitations on the disclosure and concepts described herein. The features of the subject matter described herein may be employed in various embodiments without departing from the scope of the concepts for which protection is sought.

[0027] As described above, high frequency leakage current from HVAC equipment combined with power frequency leakage current can increase the current flowing through the ground conductor in the supply line to exceed the acceptable ground fault current threshold, which can cause the GFCI circuit breaker to frequently trip. Existing GFCI circuit breakers can provide some accommodation for high frequency leakage current from HVAC equipment by adjusting the GFCI response to ignore some of the high frequency leakage current. However, existing GFCI circuit breakers do not address the situation where the power frequency leakage current exceeds the release current, which is generally considered to be from 4mA to 6mA, although a lower threshold current value of 3.5mA may be allowed under high or low ambient temperature conditions.

[0028] Embodiments of the present invention provide systems and methods for preventing power frequency leakage current values ​​above the release current. The embodiments described herein provide release protection from electric shock from each ungrounded conductor to earth, while also allowing normal leakage current from HVAC and other types of equipment and appliances to flow back to the power source through the grounding conductor. These embodiments allow up to 15mA of power frequency leakage current to flow to the ground within the equipment, which allows the equipment to operate within the normal leakage current range. Leakage current flowing from the ungrounded conductor to earth is detected at 6mA, similar to a Class A GFCI.

[0029] In some embodiments, the systems and methods herein may be implemented as a ground fault interrupt system that is specifically developed for installation at an outdoor outlet disconnect location near HVAC equipment. This is a great advantage to technicians when installing and troubleshooting a ground fault interrupt system because the system reset switch and other components can be directly accessed at the outdoor disconnect near the equipment, rather than at the main distribution board.

[0030] The ground fault interrupt system herein may be powered and operated by two ungrounded conductors that are typically available at the outlet disconnect, thereby eliminating the need for an additional neutral conductor, which may not be available in an existing facility. In addition, the ground fault interrupt system herein may include a controllable disconnect contact that automatically opens when there is no voltage between the ungrounded conductors. This helps mitigate situations where one of the two ungrounded conductors loses power, which would typically result in a loss of protection for the ungrounded conductor that remains energized.

[0031] The ground fault interruption systems herein may also include monitoring, status and / or diagnostic functionality (i.e., supervisory controllers) that provide system status information to a user. This information may be provided to the user remotely via a wired or wireless communication system, or locally via a user interface (e.g., LED, LCD display, etc.) on the device itself. The status or diagnostic information may provide notifications to a user or technician regarding abnormal or unusual currents, such as when leakage current exceeds an expected range but is still below a level at which the system will trip, or information regarding leakage current levels present when the system trips, etc. Other benefits and advantages of the ground fault interruption systems disclosed herein will be apparent to one of ordinary skill in the art.

[0032] Reference now Figure 1, shows a high-level diagram of an exemplary system equipped with a ground fault interrupt system according to an embodiment of the present invention. The exemplary system designated herein as 100 is a residential HVAC system that includes an outdoor compressor unit 102 connected to a distribution board 106 at a residence 108 via a power supply line 104. The operation of the HVAC system 100 is generally known to those skilled in the art, so a detailed description is omitted here for the sake of economy. It can be said that the distribution board 106 connects the AC line current from the utility power supply to the power supply line 104 to provide current to the compressor unit 102 to operate the compressor unit. Although a residential HVAC system 100 is shown and described herein, it should be understood that embodiments of the present disclosure may also be used in industrial / commercial HVAC facilities, as well as other types of equipment and appliances, whether industrial / commercial or residential, which may benefit from an external or outdoor ground fault interrupt system. Exemplary equipment and appliances may include patio heaters, porch stoves, hot tubs, etc.

[0033] According to an embodiment of the present invention, instead of a typical outdoor socket disconnect device, the system 100 herein includes an outdoor ground fault interrupt system 110. The ground fault interrupt system 110 is installed in the supply line 104 between the compressor unit 102 and the distribution board 106, and not only provides a manual disconnect capability similar to the socket disconnect, but also provides a ground fault and release current detection capability that has not been found in outdoor disconnects to date. This allows the system 100 to operate normally without the need for a GFCI circuit breaker in the distribution board 106, but still prevents the release of current levels and resulting electric shock. Preferably, the ground fault interrupt system 110 has a weatherproof housing, such as a molded housing, which allows the system 110 to maintain operational integrity even in inclement weather. The ground fault interrupt system 110 can then be implemented in the form of a circuit breaker or similar circuit interruption device encapsulated in such a housing.

[0034] In some embodiments, the ground fault interrupt system 110 is configured to communicate with an external monitoring and control application or app 112 that monitors the current flowing through the power supply line 104 for diagnostic purposes. The monitoring and control application 112 can reside on a local device, such as a smart phone or tablet, and can run on a wired or wireless network 114. In some embodiments, the network 114 on which the monitoring and control application 112 runs can be a local residential network, an enterprise network, or a cloud-based network. Examples of suitable external monitoring and control applications that can be used as monitoring and control applications 112 include Wiser Monitor available from Schneider Electric, etc. Such a monitoring and control application 112 can then receive the above-mentioned status or diagnostic information and display or provide the information to a user or technician in the form of one or more notifications, warnings, and alarms.

[0035] Figure 2 A circuit diagram of a system 100 and a ground fault interruption system 110 according to an embodiment of the present invention is shown. It can be seen that the supply line 104 of the system 100 includes a first ungrounded conductor "L1", a second ungrounded conductor "L2" and a ground conductor "G", which are all connected as shown. These supply lines 104 (i.e., branch circuit conductors) carry the AC line current from the distribution board 106 to the ground fault interruption system 110, and from the system 110 to the compressor unit 102. For the sake of completeness, the neutral conductor "N" and the ground "E" are also drawn here.

[0036] The ground fault interruption system 110 has a plurality of functional components, shown as discrete blocks, any of which may be divided into two or more constituent blocks, and / or any two of which may be combined into a single block, depending on the implementation. In this example, the ground fault interruption system 110 has a supervisory controller 200 that is communicatively coupled to and operable to control dual ground fault sensors. The first ground fault sensor is a low leakage sensor consisting of a low current ground fault interrupting device ("GFID5") connected to a first current sensor 204, which may be a current transformer in some embodiments that surrounds or otherwise electromagnetically couples to two ungrounded conductors L1 and L2 and a ground conductor G. The second ground fault sensor is a high leakage sensor consisting of a high current ground fault interrupting device ("GFID20") 206 connected to a second current sensor 208 that senses only the current flowing through the two ungrounded conductors L1 and L2. In some embodiments, the second current sensor 208 may also be a current transformer that surrounds or is electromagnetically coupled to the two ungrounded conductors L1 and L2 .

[0037] There are also two double-pole contact switches in the ground fault interruption system 110, namely, the line side contact switch 210 and the load side contact switch 212. As described above, the line side contact switch 210 is connected to the supervisory controller 200 and can be controlled by the supervisory controller 200 to interrupt the current through the ungrounded conductors L1 and L2 based on any abnormal or unusual current detected by the supervisory controller 200. In addition, the line side contact switch 210 is also connected to and can be controlled by the local disconnect handle 214, which is mechanically coupled to the line side contact switch 210. The disconnect handle 214 allows a technician to manually control the contact switch 210, as shown in dashed lines, to interrupt the current through the ungrounded conductors L1 and L2. The load side contact switch 212 can be independently controlled by the low current ground fault interruption device 202 and the high current ground fault interruption device 206, as shown in dashed lines. It should be understood that in addition to the above-mentioned double-pole contact switches, other types of switches and relays capable of interrupting the current in the conductors may also be used, such as solid-state switches, electromechanical relays, and other current interruption switches.

[0038] In general, the supervisory controller 200, or more specifically, its functions, can be implemented using any suitable processing unit capable of executing program code, including a microprocessor (P), a microcontroller, an application specific integrated circuit (ASIC), a programmable logic controller (PLC), a field programmable gate array (FGPA), etc., or an analog or digital detection circuit that implements the same functions. Similarly, the low-current and high-current ground fault interrupt devices 202 and 206, or more specifically, their functions, can be implemented using any suitable processing unit capable of executing program code, including a microprocessor, a microcontroller, an ASIC, an FPGA, etc., or an analog or digital detection circuit that implements the same functions.

[0039] Due to the ground fault detection and interruption capabilities of the ground fault interruption system 110 disclosed herein, the residence no longer needs to include GFCI capabilities at the distribution board 106 that supplies power to the HVAC unit 102, because the ground fault detection and circuit interruption can now be provided by the ground fault interruption system 110. In fact, in the example shown, a simple thermal magnetic circuit breaker 216 can be used with the distribution board 106.

[0040] With respect to the HVAC unit 102, in this example, the unit 102 includes a high frequency AC inverter unit 220 and an HVAC compressor 222, housed within a metal housing or casing 224. The AC inverter unit 220, as the name implies, is used to convert the AC line current from the two ungrounded conductors L1 and L2 into a form usable by the compressor 222. At the same time, the compressor 222 is intentionally allowed to generate up to 15 mA of leakage current during normal operation.

[0041] The operation of the ground fault interruption system 110 is generally as follows. The low current ground fault interruption device 202 provides 6 mA ground fault protection (i.e., release current) for leakage current from the ungrounded conductor L1 or L2 to the earth E. On the other hand, the high current ground fault interruption device 202 provides 15-20 mA leakage protection for leakage current from the ungrounded conductor L1 or L2, which flows back to the ground conductor G through the metal housing or casing 224. No ground monitoring is required. Instead, when the ground conductor G is disconnected, the low current ground fault interruption device 202 will detect any current (e.g., about 5 mA) flowing through the metal housing or casing 224 of the compressor 222 to the earth E and automatically disconnect the load side contact 212.

[0042] Figure 3 An example of the ground fault interrupt system 110 operating in the case where the normal leakage current of the compressor 222 is 15 mA is shown. In this example, the normal compressor leakage current, designated herein as 300, flows from the second ungrounded conductor L2 through the housing 224 of the compressor 222 and returns through the ground conductor G. This leakage current 300 is cancelled at the first current sensor 204 because both the second ungrounded conductor L2 and the ground conductor G pass through the current sensor 204. Therefore, the leakage current 300 is not detected by the low current ground fault interrupt device 202, so the device 202 does not open the load side contacts 212, and the compressor 222 is allowed to continue to operate.

[0043] On the other hand, the leakage current 300 is not offset at the second current sensor 208 and is therefore detected by the high current ground fault interrupt device 206. However, since the leakage current 300 does not exceed the 15-20 mA current threshold of the high current ground fault interrupt device 206, the device 206 does not automatically open the load side contact 212, and the compressor 222 is allowed to continue to operate. In this way, the ground fault interrupt system 110 can accommodate normal amounts of leakage current up to 15 mA from the compressor 222. In contrast, once the compressor leakage current 300 exceeds 6 mA, the existing ground fault interrupt device will have to trip.

[0044] Figure 4Another example of the ground fault interrupt system 110 in operation is shown, with the normal leakage current of the compressor 222 being 15 mA. However, in this example, the expected path of the compressor leakage current, designated here as 400, has been changed from the grounded conductor G to through the earth E. This situation may occur, for example, if the second ungrounded conductor L2 comes into contact with a person standing on the ground. That person will suddenly establish a path, designated here as 402, from the second ungrounded conductor L2 to the earth E. When this happens, the AC line current from the ungrounded conductor L2 bypasses the grounded conductor G and instead flows through the new path 402 and back through the earth E. As a result, the leakage current 400 is no longer cancelled at the first current sensor 204 and can now be detected by the low current ground fault interrupt device 202. Since this leakage current 400 is greater than the 6 mA threshold of the low current ground fault interrupt device 202, the device 202 automatically opens the load side contacts 212 to interrupt the current flow to the compressor 222.

[0045] Figure 5 Another example of the ground fault interrupt system 110 in operation is shown, with the normal leakage current of the compressor 222 being 15 mA. In this example, the expected path of the compressor leakage current, designated here as 500, has again been changed from the ground conductor G to through the earth E. In this case, the ground conductor G has been disconnected or separated from the housing of the compressor 222, so that a potential is generated on the housing due to the AC line current continuing to flow through the compressor 222 from the second ungrounded conductor L2. A person standing on the ground who happens to touch the housing 224 of the compressor 222 will suddenly establish a path to the earth E, represented here as 502. When this happens, the AC line current from the conductor L2 again bypasses the ground conductor G and returns through the earth E. As a result, the leakage current 500 is no longer offset at the first current sensor 204 and can now be detected by the low current ground fault interrupt device 202. Because this leakage current 500 is greater than the 6 mA threshold of the low current ground fault interrupt device 202, the device 202 again automatically opens the load side contacts 212 to interrupt the current flow to the compressor 222.

[0046] Figure 6Another example of the ground fault interrupt system 110 in operation is shown, with a normal leakage current of 15 mA for the compressor 222. In this example, one of the line side ungrounded conductors, such as the first ungrounded conductor L1, has been disconnected or separated. When this occurs, the load side contacts 212 are configured to automatically disconnect because no power is available at the ground fault interrupt system 110 to detect the disconnection. To achieve this automatic disconnection of the contacts 212, in some embodiments, the contacts 212 are configured in a normally open configuration so that they automatically disconnect when power is lost. In a similar manner, the supervisory controller 200 can also detect contact welding of the line side contacts 210 or the load side contacts 212, which may occur when a sufficiently high current flows through the contacts. Upon detecting such contact welding, the supervisory controller 200 automatically disconnects the line side or load side contacts 210 or 212 again, as the case may be, or causes the contacts to open, for example, by the low current device 202 or the high current device 206.

[0047] In the foregoing examples, the compressor leakage current is described as flowing through the second ungrounded conductor L2. However, it should be understood that the compressor leakage current may also flow through the first ungrounded conductor L1, and generally, the principles and teachings discussed herein apply equally to either case.

[0048] Now turn to Figure 7 , the flowchart 700 shown represents an exemplary method that can be used by or with an embodiment of the present invention. The method generally begins at box 702, where a ground fault interruption system for a device having a dual ground fault sensor is provided. In this example, the device can be an HVAC device, or the device can be any type of device that can benefit from the method of interrupting an outdoor ground fault disclosed herein. The dual ground fault sensor includes a low current sensor and a high current sensor, similar to the low current and high current sensors discussed above in some embodiments. Therefore, in some embodiments, the first ground fault sensor has a low leakage sensor consisting of a low current ground fault interrupting device connected to a first current sensor, the first current sensor can be a current transformer, and the second ground fault sensor has a high leakage sensor consisting of a high current ground fault interrupting device connected to a second current sensor, the second current sensor can also be a current transformer. In addition, both ground fault sensors are connected to a set of load-side contacts, and a set of load-side contacts can be independently controlled, similar to the above discussion.

[0049] In box 704, the ground fault interruption system is installed or assembled outdoors near the equipment, such as on the exterior wall of a residence. In box 706, the line-side power supply line and the load-side power supply line are connected to the line side and the load side of the ground fault interruption system, respectively. The power supply line typically includes a first ungrounded conductor, a second ungrounded conductor, and a grounded conductor, which are arranged in a manner similar to that described above. Therefore, the current through the first and second ungrounded conductors and the grounded conductor is sensed by the first current sensor, while the second current sensor only senses the current through the two ungrounded conductors. In some embodiments, in addition to the grounded conductor and the ungrounded conductor, the power supply line may also include a neutral conductor (grounded conductor).

[0050] In box 708, the device is operated under normal operating conditions, where the device is known to generate leakage currents up to 15 mA. In box 710, the leakage current is received from the device at the ground fault interruption system. In box 712, the current in the first and second ungrounded conductors and the grounded conductor is monitored at the low current sensor. In box 714, the current in the first and second ungrounded conductors is monitored at the high current sensor. At box 716, the current readings from the low current sensor and the high current sensor are analyzed, and any diagnostics are transmitted to the monitoring and control application to notify the user, if necessary, as described above.

[0051] At block 718, a determination is made by the first and second ground fault sensors as to whether a ground fault is detected by either sensor. If the determinations of both the first and second ground fault sensors are negative, the method returns to block 708 where the device continues to operate under normal operating conditions. If the determination of either the first or second ground fault sensor is positive, at 720, the ground fault interruption system opens the load side contacts of the ungrounded conductor to interrupt current flow to the HVAC system.

[0052] Thus, in some embodiments, as described above, a ground fault interruption system for an outdoor device located in a socket disconnect position includes the following elements:

[0053] -Ground fault detection device with two-stage ground fault protection.

[0054] - A ground fault sensing circuit for detecting a "release" level ground fault current, which is generally considered to be in the 4-6mARMS range, or other threshold current levels based on other physiological effects. This first ground fault sensing circuit ignores leakage current returning through the ground conductor. This first ground fault sensing circuit is intended to provide "release" ground fault protection for the circuit conductors.

[0055] - A second ground fault detection circuit for detecting higher level ground fault currents in the 15 to 20 mA range. This second ground fault detection circuit does not ignore leakage currents returning through the ground conductor. The second ground fault detection circuit is designed to protect equipment from excessive leakage currents.

[0056] - a set of controlled open contacts that can be opened to disconnect an ungrounded conductor from the wiring. The set of controlled open contacts can be opened by detecting a ground fault from a first ground fault sensing circuit. The set of controlled open contacts can be opened by detecting a ground fault from a second ground fault sensing circuit. The set of controlled open contacts automatically opens when either line side voltage terminal loses power. The set of controlled open contacts can be automatically reclosed after a ground fault is detected from either of the two detection circuits, either by a manual interface on the ground fault interrupting device or after a specified time delay. The set of controlled open contacts can be reclosed by a remote device via a communication system.

[0057] - A set of uncontrolled contacts for manually disconnecting and isolating the device from the power supply. This set of uncontrolled contacts may include a trip function that can operate in the event of an incorrect state of the controlled contacts (e.g. welding contacts).

[0058] -The ground fault interrupting device includes two or more line side voltage terminals. The ground fault interrupting device also includes two or more current carrying conductor terminals for wire connection. The ground fault interrupting device also includes a service entrance side grounding conductor connection. The ground fault interrupting device also includes an equipment side grounding conductor connection.

[0059] -The wiring between the ground-fault interrupting device and the equipment consists of at least two current-carrying conductors and a grounding conductor.

[0060] - The ground fault interrupting device may include communication means for power monitoring, status and diagnostics.

[0061] -Communications for status and diagnostics include the ability to detect leakage currents approaching the threshold at which the device is configured to trip (e.g., a leakage greater than 10 mA but still less than the 15-20 mA threshold may be communicated to the user as a condition that the system may require maintenance). Such monitoring, status, and diagnostic information may also be available locally on the ground fault interrupting device in the form of a user interface that includes a display and / or other visual indicators.

[0062] -The ground fault interrupt device for outdoor equipment is located at the receptacle / disconnect near the equipment to facilitate servicing and troubleshooting of the equipment.

[0063] Now go to Figure 8, the exemplary controller system 800 shown may be used to implement various embodiments of the present invention, including the supervisory controllers and low current and high current sensors described herein. The controller system 800 may include a processor 820 connected to one or more memory devices 830, such as solid-state memory or other devices for storing data. The memory 830 is typically used to store programs and data used during operation of the controller system 800. The controller system 800 may also include a storage system 850 that provides additional storage capacity. The components of the controller system 800 may be connected by an interconnection mechanism 840, which may include one or more buses (e.g., between components integrated within the same system) and / or networks (e.g., between components located on separate discrete systems). The interconnection mechanism 840 enables communications (e.g., data, instructions) to be exchanged between system components of the system 800.

[0064] The controller system 800 also includes one or more input devices 810, including, for example, sensor inputs and user inputs, and one or more output devices 860, including, for example, control signals and display screens. The display screens may include touch screens and similar user interface screens that allow a user to configure, operate, and otherwise interact with the controller system 800. In addition, the controller system 800 may include one or more interfaces (not shown) that connect the controller system 800 to a wired or wireless communication network (in addition to or as an alternative to the interconnect mechanism 840).

[0065] Fig. 9 The storage system 850 shown in detail in FIG. 1 generally includes a computer-readable and writable non-volatile recording medium 910, in which signals are stored, the signals defining a program to be executed by the processor 820 or information stored on or in the medium 910 to be processed by the program to perform one or more functions related to the embodiments described herein. The medium may be, for example, a flash memory. Typically, in operation, the processor 820 reads data from the non-volatile recording medium 910 into the storage system memory 920, which allows the processor to access information faster than the medium 910. The storage system memory 920 may be a volatile random access memory, such as a dynamic random access memory (DRAM) or a static memory (SRAM). As shown, the storage system memory 920 may be located in the storage system 850, or in the system memory 830. The processor 820 generally manipulates the data within the memory system 920, and then copies the data to the medium 910 after the processing is completed. A variety of mechanisms are known for managing data movement between the medium 910 and the integrated circuit storage element 920, and the present disclosure is not limited thereto. The present disclosure is not limited to a particular memory 920 , memory 830 , or storage system 850 .

[0066] The controller system 800 may include specially programmed dedicated hardware, such as an application specific integrated circuit (ASIC). Various aspects of the present disclosure may be implemented in software, hardware, or firmware, or any combination thereof. In addition, such methods, acts, systems, system elements, and components thereof may be implemented as part of the above-described controller system or as standalone components. Although the controller system 800 is shown as an example of a type of controller system on which various aspects of the present disclosure may be implemented, it should be understood that aspects of the present disclosure are not limited to such controller systems. Figure 8 The controller system shown is implemented.

[0067] In the above, reference is made to various embodiments. However, the scope of the present disclosure is not limited to the specifically described embodiments. On the contrary, any combination of the described features and elements, whether or not related to different embodiments, is considered to implement and practice the contemplated embodiments. In addition, although the embodiments may achieve advantages over other possible solutions or prior art, whether a given embodiment achieves a particular advantage does not limit the scope of the present disclosure. Therefore, the foregoing aspects, features, embodiments and advantages are merely illustrative and are not considered to be elements or limitations of the appended claims unless expressly stated in the claims.

[0068] It should be understood that the development of actual commercial applications incorporating aspects of the disclosed embodiments will require many implementation-specific decisions to realize the commercial embodiments. Such implementation-specific decisions may include, and may not be limited to, compliance with system-related, business-related, government-related, and other constraints, which may vary with the specific implementation, location, and time. While the developer's efforts may be considered complex and time-consuming, such efforts are still routine tasks for those skilled in the art who benefit from this disclosure.

[0069] It should also be understood that the embodiments disclosed and taught herein are susceptible to numerous modifications and alternative forms. Therefore, the use of singular terms, such as but not limited to "one", etc., is not intended to limit the number of items. Similarly, any relative terms used in the written description, such as but not limited to "top", "bottom", "left", "right", "upper", "lower", "upper", "side", etc., are for clarity when specifically referring to the drawings, and are not intended to limit the scope of the present invention.

[0070] The application of the present invention is not limited to the structural details and component arrangements set forth in the following description or shown in the accompanying drawings. The present disclosure is capable of other embodiments and can be practiced or carried out in various ways. In addition, the words and terms used herein are for descriptive purposes and should not be considered limiting. The use of "includes," "comprising," "having," "containing," "involving," and variations thereof herein is meant to be open ended, i.e., "including but not limited to."

[0071] It should also be understood that the above description is intended to be illustrative, not restrictive. After reading and understanding the above description, many other implementation examples are apparent. Although the present disclosure describes specific examples, it should be appreciated that the systems and methods of the present disclosure are not limited to the examples described herein, but can be modified to be implemented within the scope of the attached claims. Therefore, the description and drawings should be considered illustrative, not restrictive. Therefore, the scope of the present disclosure should be determined with reference to the full scope of the attached claims and the equivalents of these claims.

Claims

1. A ground fault monitoring and detection system, comprising: a current interrupter switch configured to be connected to a power supply line; a first leakage sensor connected to the current interruption switch, the first leakage sensor being configured to detect a leakage current in the power supply line and control the current interruption switch to interrupt the current passing through the power supply line if the leakage current exceeds a first current threshold; and a second leakage sensor connected to the current interruption switch, the second leakage sensor being configured to detect a leakage current in the power supply line and control the current interruption switch to interrupt the current passing through the power supply line if the leakage current exceeds a second current threshold; The first current threshold is a release current, and the second current threshold is greater than the release current by a predetermined amount.

2. The system of claim 1, wherein the first leakage sensor comprises a first ground fault interrupt device (GFID) connected to a first current sensor, and the second leakage sensor comprises a second GFID connected to a second current sensor.

3. The system of claim 1 , wherein the power supply line comprises a first ungrounded conductor, a second ungrounded conductor, and a grounded conductor, and wherein the second leakage sensor is configured to detect a leakage current through the first and second ungrounded conductors, and the first leakage sensor is configured to detect a leakage current through the first and second ungrounded conductors and the grounded conductor.

4. The system of claim 1, wherein the current interrupt switch is a load-side current interrupt switch, the system further comprising a line-side current interrupt switch configured to be connected to the power supply line.

5. The system of claim 4, further comprising a supervisory controller connected to the line-side current interruption switch, the supervisory controller being configured to control the line-side current interruption switch to interrupt the current through the power line when a predetermined current interruption event occurs.

6. The system of claim 4, further comprising a local disconnect handle mechanically coupled to the line-side current interruption switch, the local disconnect handle configured to be operated by a user to manually interrupt current through the power supply line.

7. The system of claim 1, further comprising a housing configured to enclose the current interrupt switch and the first and second leakage sensors, the housing providing weather protection for the current interrupt switch and the first and second leakage sensors.

8. The system of claim 5, wherein the supervisory controller is coupled to first and second leakage sensors, the supervisory controller being configured to perform diagnostics on leakage currents detected by the first and second leakage sensors and to provide status and diagnostic information to a user.

9. A method for providing ground fault monitoring and detection, the method comprising: providing a current interruption switch configured to be connected to a power supply line; connecting a first leakage sensor to the current interruption switch, the first leakage sensor being configured to detect a leakage current in the power supply line and controlling the current interruption switch to interrupt the current through the power supply line if the leakage current exceeds a first current threshold; and connecting a second leakage sensor to the current interruption switch, the second leakage sensor being configured to detect a leakage current in the power supply line and controlling the current interruption switch to interrupt the current through the power supply line if the leakage current exceeds a second current threshold; The first current threshold is a release current, and the second current threshold is greater than the release current by a predetermined amount.

10. The method of claim 9, wherein the first leakage sensor comprises a first ground fault interrupt device (GFID) connected to a first current sensor, and the second leakage sensor comprises a second GFID connected to a second current sensor.

11. The method of claim 9, wherein the power supply line includes a first ungrounded conductor, a second ungrounded conductor, and a grounded conductor, further comprising connecting a second leakage sensor to detect a leakage current through the first and second ungrounded conductors, and connecting the first leakage sensor to detect a leakage current through the first and second ungrounded conductors and the grounded conductor.

12. The method of claim 9, wherein the current interrupt switch is a load-side current interrupt switch, the method further comprising connecting a line-side current interrupt switch to the power supply line.

13. The method of claim 12, further comprising connecting a supervisory controller to the line-side current interruption switch, the supervisory controller configured to control the line-side current interruption switch to interrupt current through the power line upon occurrence of a predetermined current interruption event.

14. The method of claim 12, further comprising mechanically coupling a local disconnect handle to the line-side current interruption switch, the local disconnect handle configured to be operated by a user to manually interrupt current through the power supply line.

15. The method of claim 9, further comprising enclosing the current interrupt switch and the first and second leakage current sensors in a housing, the housing being configured to provide weather protection for the current interrupt switch and the first and second leakage current sensors.

16. The method of claim 13, further comprising coupling the supervisory controller to first and second leakage current sensors, the supervisory controller configured to perform diagnostics on leakage currents detected by the first and second leakage current sensors and provide status and diagnostic information to a user.

17. A heating, ventilation and air conditioning (HVAC) system, the HVAC system comprising: Switchboards; Supply wires connected to the distribution board; HVAC equipment connected to the power supply line; Current interrupter switches, which connect to the supply lines between the electrical panel and the HVAC equipment; a first leakage sensor connected to the current interruption switch, the first leakage sensor configured to detect a leakage current in the power supply line and control the current interruption switch to interrupt current to the HVAC equipment if the leakage current exceeds a first current threshold; and a second leakage sensor connected to the current interruption switch, the second leakage sensor configured to detect a leakage current in the power supply line and control the current interruption switch to interrupt current to the HVAC equipment if the leakage current exceeds a second current threshold; The first current threshold is a release current, and the second current threshold is greater than the release current by a predetermined amount.

18. The HVAC system of claim 17, wherein the first leakage sensor comprises a first ground fault interrupt device (GFID) connected to a first current sensor, and the second leakage sensor comprises a second GFID connected to a second current sensor.

19. The HVAC system of claim 17, wherein the power supply line comprises a first ungrounded conductor, a second ungrounded conductor, and a grounded conductor, and wherein the second leakage sensor is configured to detect a leakage current through the first and second ungrounded conductors, and wherein the first leakage sensor is configured to detect a leakage current through the first and second ungrounded conductors and the grounded conductor.

20. The HVAC system of claim 17, wherein: The current interrupt switch is a load-side current interrupt switch, and the HVAC system further includes a line-side current interrupt switch configured to be connected to a power supply line between a distribution panel and the HVAC equipment.

21. The HVAC system of claim 20, further comprising a supervisory controller connected to the line-side current interruption switch, the supervisory controller configured to control the line-side current interruption switch to interrupt current to the HVAC equipment when a predetermined current interruption event occurs.

22. The HVAC system of claim 20, further comprising a local disconnect handle mechanically coupled to the line-side current interrupt switch, the local disconnect handle configured to be operated by a user to manually interrupt current to the HVAC equipment.

23. The HVAC system of claim 17, further comprising a housing configured to enclose the current interrupt switch and the first and second leakage sensors, the housing providing weather protection for the current interrupt switch and the first and second leakage sensors.

24. The HVAC system of claim 21, wherein the supervisory controller is connected to first and second leakage sensors, the supervisory controller being configured to diagnose leakage currents detected by the first and second leakage sensors and to provide status and diagnostic information to a user.

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