Compliant hazardous environment circuit protection devices, systems and methods

Abstract

The present invention provides a solid-state circuit protection device and a hybrid circuit protection device, which include improved arc-free switching capability and overcurrent protection, improved terminal assemblies, and improved thermal management features that reduce or eliminate ignition sources for hazardous environments. The solid-state circuit protection device and the hybrid circuit protection device are ignition-proof and avoid possible explosions, thereby eliminating the need for conventional explosion-proof enclosures to ensure safe operation of power systems in hazardous locations.

Description

Background Art

[0001] The field of the present invention relates generally to circuit protection devices, and more particularly to compliant circuit protection devices that meet or exceed applicable standards and requirements for operation in hazardous environments.

[0002] In order to meet the needs of power systems that provide power to various electrical loads, there are various different types of circuit protection devices. For example, various different devices and assemblies are known that provide a circuit breaking function between a power supply circuit and an electrical load. With such devices, output power can be selectively switched from a power supply, either manually or automatically, to facilitate maintenance of the power system and to resolve electrical fault conditions. Circuit breaker devices and fusible disconnect switch devices are two well-known types of devices that each provide different capabilities for responding to overcurrent and electrical fault conditions and for electrically isolating load-side electrical equipment from line-side power circuits, thereby protecting load-side devices and circuits from other destructive overcurrent conditions in the power system.

[0003] Although there are known circuit breaker disconnect devices that meet the needs of many electrical systems, they are still disadvantageous in some aspects for certain types of electrical systems and applications where the circuit breaker is located in a hazardous location. Therefore, existing circuit breaker disconnect devices have not yet fully met the market demand. Therefore, there is a need for improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various figures unless otherwise specified.

[0005] Figure 1 is a perspective view of a compliant hazardous location arc-free circuit protection device according to a first exemplary embodiment of the present invention.

[0006] Figure 2 is an exemplary solid state configuration Figure 1 A simplified schematic diagram of a circuit protection device is shown.

[0007] Figure 3 yes Figure 1 and Figure 2 A block diagram of a circuit protection device is shown.

[0008] Figure 4 is used for Figures 1 to 3 A cross-sectional view of a first exemplary terminal assembly of a circuit protection device is shown.

[0009] Figure 5 is used for Figures 1 to 3 A cross-sectional view of a second exemplary terminal assembly of a circuit protection device is shown.

[0010] Figure 6 is used for Figures 1 to 3 A cross-sectional view of a third exemplary terminal assembly of a circuit protection device is shown.

[0011] Figure 7 is used for Figures 1 to 3 A cross-sectional view of a fourth exemplary terminal assembly of a circuit protection device is shown.

[0012] Figure 8 is used for Figures 1 to 3 A perspective view of a fifth exemplary terminal assembly for a circuit protection device is shown.

[0013] Fig. 9 The schematic diagram shows the Figures 1 to 3 Example thermal management features of a circuit protection device are shown.

[0014] Fig.10 is a perspective view of a compliant hazardous location arc-free circuit protection device according to a second exemplary embodiment of the present invention.

[0015] Fig.11 is an exemplary hybrid configuration Fig.10 A simplified schematic diagram of a circuit protection device is shown.

[0016] Fig.12 yes Fig.10 and Fig.11 A block diagram of a circuit protection device is shown.

[0017] Fig.13 The schematic diagram shows the Figures 10 to 12 Thermal management features of a circuit protection device are shown.

[0018] Fig.14 An exemplary switchboard including compliant hazardous location arc-free circuit protection devices is shown.

[0019] Fig.15 is an exemplary circuit diagram for a power electronic topology having a circuit protection device with a hybrid configuration.

[0020] Fig.16 is an alternative solid-state switching device arrangement for a circuit protection device according to an embodiment of the present invention.

[0021] Fig.17 Is used for Fig.16 An exemplary circuit diagram of a power electronic topology of a circuit protection device of a hybrid configuration is shown.

[0022] Fig.18 is an exemplary circuit diagram of a power electronic topology for a circuit protection device having a solid-state configuration. DETAILED DESCRIPTION

[0023] In order to maximize the understanding of the inventive concepts described herein, a discussion of the prior art as it relates to problems caused by power systems operating in hazardous locations is set forth below, followed by exemplary embodiments of circuit protection devices, systems, and methods that address such problems and satisfy a long-standing but unmet need in the art.

[0024] I. Prior Art

[0025] Electrical systems sometimes operate in hazardous environments where there is a risk of explosion due to ignition of surrounding gases or vapors, dust, fibers, or flying dust. By way of example only, such hazardous environments may be found in refineries, petrochemical plants, grain silos, wastewater and / or treatment facilities, and other industrial facilities where persistent or unstable conditions in the surrounding environment may exist and may increase the risk of fire or explosion. The occasional or persistent presence of flammable gases, flammable vapors, or combustible dusts or other flammable materials in the air presents a significant challenge to the overall safe and reliable operation of these facilities, including but not limited to the safe operation of the electrical system itself, where, in certain circumstances, conventional circuit protection devices may create an ignition source both during normal operation and in the event of an electrical fault. Therefore, a number of standards for the use of electrical products in hazardous environments have been promulgated to improve safety in hazardous locations based on the assessed probability of explosion or fire risk.

[0026] For example, the Underwriter's Laboratories (UL) standard UL1203 sets the standard for explosion-proof and dust-ignition-proof electrical equipment for use in hazardous locations. Currently, there are explosion-proof and dust-ignition-proof enclosures that can be used to enclose or contain electrical products, including but not necessarily limited to circuit protection devices that are not themselves explosion-proof and dust-ignition-proof. In conjunction with the appropriate explosion-proof and dust-ignition-proof enclosures, electrical equipment manufacturers can obtain UL certification to demonstrate that they meet the rating standards applicable to hazardous locations. UL certification is an important aspect of a manufacturer's ability to successfully market products in the North American market or any other market that accepts the UL1203 standard.

[0027] Article 500 of the National Electrical Code (NEC) of the United States sets forth the hazardous location coding system, and the NEC generally classifies hazardous locations by class and segment. Class I locations are those locations where flammable vapors and gases may be present. Class II locations are those locations where combustible dusts are present. Class III locations are those locations that are hazardous due to the presence of easily ignited fibers or flyings. Class I, Division 1 covers locations where flammable gases or vapors may be present under normal operating conditions, under frequent repair or maintenance operations, or where failure or misoperation of process equipment may also cause simultaneous failure of electrical equipment. Class I, Division 2 covers locations where flammable gases, vapors, or volatile liquids are handled in closed systems or confined within suitable enclosures, or where hazardous concentrations are generally prevented by active mechanical ventilation. Areas adjacent to Section 1 locations into which gases may occasionally flow also fall into Section 2. Similar segments are defined in the NEC for the remaining classes.

[0028] Likewise, the International Electrotechnical Commission (IEC) classifies hazardous locations as Zone 0, Zone 1, or Zone 2, which represent locations where the air carries or may carry flammable gases or vapors in quantities sufficient to produce an explosive or ignitable mixture. As defined by the IEC, a Zone 0 location is a location where ignitable concentrations of flammable gases or vapors may be present under normal operating conditions; or a location where ignitable concentrations of flammable gases or vapors may be present frequently due to repair or maintenance operations or due to leaks; or a location where equipment is operated or processes are performed, the nature of which is such that equipment failure or erroneous operation may result in the release of ignitable concentrations of flammable gases or vapors, and may also result in the simultaneous failure of electrical equipment in a mode that makes the electrical equipment a source of ignition; or a location adjacent to a Zone 1 location from which ignitable concentrations of vapors may be transmitted.

[0029] Although the wording is different, in actual hazardous environment assessments, IEC Zone 1 and NEC Section 2 generally cover common locations. In view of modern environmental regulations and the centralized nature of Section 1 and Zone 0 applications, most hazardous equipment, especially switchgear products for power systems, are installed and used in Section 2 or Zone 1 (or Zone 2) areas. Since electrical devices (such as those described below) can be ignition sources in some cases, explosion-proof, flameproof or ignition-proof enclosures are usually set in NEC Section 2 locations and / or IEC Zone 1 locations to accommodate electrical devices that would otherwise pose an ignition risk. In this article, the term "explosion-proof" or "fireproof" refers to an enclosure designed to control an internal explosion caused by a specified flammable vapor-air mixture. In addition, the explosion-proof or fireproof enclosure must operate at a safe temperature relative to the surrounding air.

[0030] Conventional circuit breaker devices, various types of switch devices and contactor devices are known to include input terminals that can be connected to a power supply or a line-side circuit, output terminals that can be connected to one or more electrical loads, and pairs of mechanical switch contacts between the corresponding input terminals and output terminals. Each pair of mechanical switch contacts generally includes a stationary contact and a movable contact connected to an actuator element, which causes the movable contact to shift toward and away from the stationary contact along a predetermined motion path to connect and disconnect the circuit path through the device, thereby electrically connecting or disconnecting the input terminal and the output terminal. When the switch contacts are disconnected, the device is used to isolate one or more electrical loads connected to the output terminal from the power supply connected to the input terminal. The actuator element in the above-mentioned mechanical switch device can be automatically moved for circuit protection purposes to disconnect the mechanical switch contacts in response to an overcurrent or fault condition in the line-side circuit, and electrically isolate the electrical loads to prevent them from being damaged, or the actuator element can be manually movable to electrically isolate the electrical load from the line-side power supply, thereby saving energy, maintaining the load, etc.

[0031] Circuit breakers and fusible disconnect switchgear are two well-known types of devices, each of which provides different types of disconnection functions and circuit protection through mechanical switch contacts. IEC includes the following relevant definitions: 2.2.11

[0033] breaker

[0034] Mechanical switching devices that are capable of connecting, carrying and disconnecting current under normal circuit conditions, and are also capable of connecting, carrying within a specified time, and disconnecting current under specified abnormal circuit conditions (such as short circuit) [441-14-20] 2.2.9

[0036] Switch (mechanical)

[0037] Mechanical switching devices capable of making, carrying and breaking current under normal circuit conditions, which may include specified operating overload conditions, and also capable of carrying current for a specified time under specified abnormal circuit conditions, such as a short circuit [441-14-10]

[0038] Note that the switch can turn on but not turn off the short-circuit current. 2.2.1

[0040] Switchgear

[0041] Devices designed to connect or disconnect current in one or more circuits[441-14-01]

[0042] Note that a switching device may perform one or both of these operations.

[0043] As can be seen from the above definitions, the difference between the circuit breaker defined in IEC 2.2.11 and the mechanical switch defined in IEC 2.2.9 lies in their different capabilities of mechanical response to abnormal circuit conditions. Specifically, the circuit breaker defined in IEC 2.2.11 can mechanically disconnect a short circuit condition, while the mechanical switch defined in IEC 2.2.9 cannot disconnect a short circuit condition. Therefore, electrical fuses are sometimes used in conjunction with the mechanical switch of IEC 2.2.9 to implement a fusible disconnect switch that can respond to a short circuit condition through the operation of the fuse (i.e., the opening of the fuse) rather than the operation of the mechanical switch contacts.

[0044] In either of IEC 2.2.11 and IEC 2.2.9, automatic circuit protection may sometimes be provided solely by the structural design and calibration of the circuit breaker structure or the fuse element structure in the fuse, provided that each achieves a predetermined time-current characteristic before the circuit is opened. The NEC has defined these two basic types of overcurrent protective devices (OCPDs) as follows:

[0045] Fuse: An overcurrent protection device with a fusible component that is heated and melted by the passage of overcurrent, thereby breaking the circuit.

[0046] Circuit Breaker: A device designed to open and close an electrical circuit in a non-automatic manner and to automatically open the circuit without damage to itself when a predetermined overcurrent is properly applied within its rating.

[0047] The NEC also requires that circuits be provided with a disconnecting device, defined as a device or group of devices, or other device that disconnects the circuit conductors from the power source to the circuit conductors. Since fuses are designed to open only when subjected to an overcurrent, fuses are often used in conjunction with a separate disconnecting device, usually some form of disconnect switch (NEC Article 240 requires this in many cases). Since circuit breakers are designed to open and close under manual operation and in response to an overcurrent, a separate disconnecting device is not required.

[0048] In some types of circuit protection devices, automatic circuit protection can be achieved by including an electrical sensor in the device to monitor the actual circuit condition, and in response to a predetermined circuit condition detected by the sensor, an electromechanical trip feature can be actuated to automatically disconnect the movable contact in response to the detected overcurrent condition (including overload and short circuit conditions). Once tripped, the circuit breaker can be reset or reclosed by the switch contacts to restore the affected circuit because the circuit breaker is designed to disconnect the circuit without damaging itself, while the fuse disconnects the circuit through internal degradation of the fuse element, which makes the fuse element no longer able to carry current. Therefore, the fuse must be replaced after disconnection to restore the affected circuit. In some cases, a combination of circuit breakers and fuses is also desirable, and they are selectively coordinated to expand the range of overcurrent conditions that can be addressed and improve response time.

[0049] Compared to the circuit protection device described above, the "switching device" of IEC 2.2.1 defined above is only concerned with making and breaking current, and not with making or breaking overcurrent conditions (i.e., overload conditions or short circuit conditions). The "switching device" of IEC 2.2.1 therefore provides a circuit breaking function, but not a circuit protection function. IEC 2.2.1 also does not require a mechanical switching device at all, but if a switching device that is not a circuit breaker device actually includes mechanical switch contacts, it may still present an ignition risk when located in a hazardous environment.

[0050] More specifically, the operation of mechanical switch contacts used to make or break an energized circuit, whether manually actuated by a user under normal circuit conditions or automatically actuated under abnormal circuit conditions, can create an ignition source in a hazardous environment. Specifically, when the movable contact is mechanically moved away from the stationary contact (e.g., from a closed position to an open position), an arc discharge between the switch contacts often results. Similar arc discharges may occur when the movable contact moves back toward the stationary contact to reclose the device. If such an arc discharge between the switch contacts is achieved in the presence of a flammable gas, vapor, or substance, the arc discharge can ignite the gas, vapor, or substance. Although the mechanical switch contacts are typically enclosed in a housing provided with a conventional circuit breaker or other mechanical switching device and an additional enclosure typically used with a switchboard or motor control center, etc., such housings and enclosures are generally not sufficient to isolate the arc from ignitable gas-borne elements. For at least this reason, known devices including mechanical switch contacts are typically located in separate explosion proof enclosures, which are then contained in an environmental enclosure, or conversely, the switching system (i.e., the switchboard) may be mounted in a single large explosion proof enclosure without the need for separate explosion proof enclosures for switches located in Section 1 or 2 locations under the NEC or Zone 1 locations under the IEC to provide the necessary protection.

[0051] In the arrangement described above, the circuit breaker, although mechanically disconnecting the short circuit condition, experiences the most intense arc discharge condition and therefore has the greatest potential to ignite flammable gases, vapors or substances in hazardous locations in terms of raw energy and temperature. Considering that many industrial power systems and loads operate at relatively high voltages and high currents, the arc energy and arc temperature under lower current overload conditions and normal conditions are also considerable and high, and therefore pose an ignition risk. Generally speaking, the ignition energy caused by the fault energy is related to the magnitude of the current being disconnected, so the larger the current being disconnected, the greater the possibility and severity of arc discharge. For example, from the perspective of arc discharge, the disconnection of 65kAIC is much more significant than the disconnection of 10kAIC, and is therefore more dangerous.

[0052] Available explosion-proof, flameproof or ignition-proof enclosures effectively enable mechanical switching devices in NEC Section 1 or Section 2 locations or IEC Zone 1 locations to operate safely, but typically incur additional costs, occupy valuable space in the power system, and over time add a certain burden to the installation and maintenance of the power system. Access to the circuit breaker within the explosion-proof enclosure typically requires time-consuming removal of multiple fasteners, and after any maintenance procedures are completed, all fasteners must be properly replaced to ensure the required safety of the explosion-proof enclosure. During the maintenance procedure, the area where the circuit breaker is located is typically shut down (i.e., disconnected), while the associated load-side processes are stopped to ensure safety during the maintenance procedure. From the perspective of industrial facilities, such downtime costs are high, and limiting or shortening downtime is important. Therefore, in some cases, if the explosion-proof enclosure can be eliminated in NEC Section 1 or Section 2 locations or IEC Zone 1 locations while still providing a safe circuit-breaking function in a hazardous environment, this would be desirable. To this end, circuit protection devices designed to reduce the risk of ignition are needed, but such devices are generally not currently available.

[0053] Solid-state disconnect devices are known that provide the desired disconnecting function through semiconductor switches or semiconductor devices such as, but not limited to, insulated gate bipolar transistors (IGBTs), metal oxide semiconductor field effect transistors (MOSFETs), and other known components that electrically operate in a known manner to prevent current from flowing through the device and thereby electrically isolate the line side circuit from the load side circuit in response to a predetermined circuit condition without utilizing mechanical switch contacts. Such solid-state switches may be implemented in a circuit breaker device or used in combination with fuses to resolve electrical fault conditions in an automated manner.

[0054] Solid-state switches advantageously eliminate arcing associated with the displacement of mechanical switch contacts as described above, but a possible source of ignition may still be created by the heat generated by the solid-state switch in use. Even if arcing does not occur during the switching operation of the device, depending on the type and concentration of flammable elements in the hazardous location, the surface temperature of the solid-state switch device may rise to a point where autoignition may occur due to the flash point temperature of the particular gas or ignitable substance in the hazardous location.

[0055] The connection terminals of solid-state switching devices may also create reliability problems and possible ignition sources when used in NEC Section 2 locations or IEC Zone 1 locations. More specifically, the terminals may tend to loosen over time when subjected to thermal cycling or vibration. In certain conditions, loose terminal connections at the terminal locations may lead to overheating and possible ignition sources (if not arcs). Poor quality connections at the terminals may also cause overheating of the conductor structure (sometimes called a bus) in the device, creating further ignition problems in hazardous locations. Therefore, if explosion-proof enclosures are not supplementarily used in NEC Section 2 locations or IEC Zone 1 locations, the use of known solid-state switching devices alone (without other devices) does not ensure adequate safety in hazardous locations.

[0056] So-called hybrid disconnecting devices are also known, which include a semiconductor switch or a combination of a semiconductor device and a mechanical switch contact. Such hybrid devices can likewise be implemented in a circuit breaker device or used in combination with a fuse to resolve electrical fault conditions in an automatic manner. Hybrid disconnecting devices create a mixture of the above-mentioned problems from the point of view of possible ignition sources in hazardous locations and do not ensure adequate safety without the supplementary use of explosion-proof enclosures in NEC Section 2 locations or IEC Zone 1 locations.

[0057] II. Inventive No-Arc Devices, Systems, and Methods for Hazardous Location Compliance .

[0058] Described herein are exemplary embodiments of circuit protection devices that overcome the above-described problems and provide an enhanced degree of safety for compliance with applicable standards for Division 2 locations of the NEC or Zone 1 locations of the IEC without necessarily requiring a separate explosion-proof, flameproof, or ignition-proof enclosure. As such, and because a separately provided flameproof or ignition-proof enclosure is eliminated, the exemplary circuit protection devices described herein reduce the cost of installing a power system, save valuable space in distribution panels, control centers, and the like, and make maintenance and monitoring of the power system more efficient. Some aspects of the method will be discussed explicitly and others will become apparent from the following description.

[0059] In one aspect, an exemplary circuit protection device may be implemented in the form of a solid-state switching device. The solid-state switching device has arc-free operation when it switches to connect or disconnect a load-side circuit, incorporates enhanced features for addressing possible ignition sources at the connection terminals, and / or includes thermal management features for addressing potential overheating of conductors in the solid-state switching device. Thus, when implemented in the form of a solid-state circuit breaker device, unlike conventional circuit breakers, such solid-state circuit breakers comply with hazardous location standards for Division 2 locations of the NEC or Zone 1 locations of the IEC, and thus allow conventional explosion-proof, flameproof, or ignition-proof enclosures to be eliminated for certain applications.

[0060] In another aspect, a hybrid circuit protection device may be implemented in the form of a combination of a solid-state switching device and a mechanical switching device, and the hybrid circuit protection device may also incorporate enhanced features to isolate the arc between the mechanical switch contacts from the surrounding environment to prevent ignition, and to address possible ignition sources at the connection terminals and / or include thermal management features to avoid possible overheating of conductive elements inside the hybrid device. Thus, unlike conventional hybrid circuit protection devices, such hybrid circuit protection devices comply with hazardous location standards applicable to NEC Division 2 locations or IEC Zone 1 locations, and allow conventional explosion-proof enclosures to be eliminated for certain applications.

[0061] Although the discussion below is conducted in the context of circuit breaker devices, the inventive concepts below are not necessarily limited to circuit breaker devices, but may be broadly applicable to other types of devices, examples of which are discussed above, and which present similar problems from the perspective of ignition problems in hazardous locations. Likewise, although the inventive concepts are described in the context of hazardous locations (such as NEC Section 2 locations or IEC Zone 1 locations), the benefits of the concepts described are not necessarily limited to NEC Section 2 locations or IEC Zone 1 locations, but may be more broadly applicable to other types of hazardous environments, and in some aspects, may be advantageously provided for use in non-hazardous locations as desired.

[0062] Figure 1 is a perspective view of a compliant hazardous environment arc-free circuit protection device 100 according to a first exemplary embodiment. Circuit protection device 100 includes a housing 102 having opposite longitudinal sides 104, 106 and opposite lateral sides 108, 110 that are generally orthogonally arranged relative to longitudinal sides 104, 106. Housing 102 also includes a front side 112 and a rear side 114, and front side 112 may include a digital display 116 that serves as a user interface for device 100. As shown, display 116 visually indicates voltage, current, power, and energy readings to a person near device 100 and display 116.

[0063] The display 116 can be a multi-function display, and thus can display different screens in response to user activation. In some embodiments, the display 116 can be touch-sensitive, and the user makes a selection by touching the selected area of ​​the display according to the prompt. An input selector (such as a button, a knob, etc.) can be provided separately from the display 116 to interact with the user relative to the display. An input selector (such as a toggle switch) can also be provided separately from the display 116 to serve as a manually operable on-off switch that can be manually operated by the user intuitively. The toggle switch can simulate a traditional toggle switch to change the state to "on" or "off", but there is no displacement of any mechanical switch contacts when doing so, because as described below, the device 100 does not include mechanical switch contacts.

[0064] Alternatively, an on / off feature may be built into the display 116 for user / operator convenience, thereby implementing a disconnect switch function for connected load-side devices. However, it should be recognized that in certain embodiments, the display or display array 116 may be considered optional and need not be included at all. In further embodiments, additional input / output elements may be provided, whether in the form of a display or other interface for user interaction with the device locally and remotely.

[0065] The lateral sides 108, 110 each include connection recesses 118, 120, 122 to achieve corresponding connections to the line side circuit and the load side circuit. In an exemplary embodiment, three connection recesses 118, 120, 122 are provided for connecting to a three-phase power supply on one of the sides 108, 110, respectively, and connecting to a three-phase load side device on the other side. The power supply and the load can each be operated with alternating current (AC) or direct current (DC). As shown, the device 100 is configured as a circuit breaker, and therefore provides automatic circuit protection in response to a predetermined overcurrent condition. The predetermined overcurrent condition can be selected by the user within a specific range and input to the device 100 via the display screen 116, via another user interface including a remote interface, and / or pre-programmed into the device. The device 100 can operate according to a specified time-current curve or trip curve suitable for providing sufficient protection for the connected load.

[0066] Figure 2 is a simplified schematic diagram of a circuit protection device 100 in an exemplary solid-state configuration. The device 100 includes input terminals 130a, 130b, 130c, each of which is connected to the circuit protection device 100 via a connecting cable, conduit or wire. Figure 2134a, 134b, 136c, each of which enables connection to a load side circuit 136, such as motors, fans, lighting fixtures, and other electrical equipment in an industrial facility where ignitable gases, vapors, or substances may be gaseous as indicated at 138. Optionally, the device 100 may also include additional elements, such as auxiliary contacts and auxiliary connections, shunt trip features, undervoltage release features, communication ports and communication elements, power ports for communication and other purposes, and the like.

[0067] Solid-state switching devices as shown in 140a, 140b and 140c are arranged between respective pairs of input terminals 130a, 130b, 130c and output terminals 134a, 134b, 136c. The exemplary solid-state switch arrangements 140a, 140b, 140c each include series-connected pairs 142a, 142b, 142c, 142d of insulated gate bipolar transistors (IGBTs) respectively connected in reverse to each other, wherein each pair of 142a, 142b, 142c, 144d includes a varistor element 146 connected in parallel to the IGBT. The reversely connected IGBTs in each pair exclude reverse current flowing from the load side circuit 136 to the line side circuit 132 through the IGBT in a known manner.

[0068] The IGBTs 142a, 142b, 142c, 142d in each arrangement 140a, 140b, 140c are a form of semiconductor switch operable to allow current to flow from the line side circuit 132 to the load side circuit 136 between the respective input and output terminals (130a and 134a, 130b and 134b, and 130c and 134c), or to prevent current from flowing through the device 100, such that the load side circuit 136 is electrically isolated from the line side circuit 132. In short, a positive voltage applied from the emitter of each IGBT to the gate terminal causes electrons to be pulled toward the gate terminal across the body region of the IGBT. If the gate-emitter voltage is equal to or higher than the threshold voltage, sufficient electrons are pulled toward the gate to form a conductive channel across the body region, thereby allowing current to flow from the collector to the emitter. If the gate-emitter voltage is lower than the threshold voltage, substantially no current can flow through the body region, so that the current between the input terminal and the output terminal can be selectively enabled or disabled by controlling the gate-emitter voltage to connect or disconnect the output terminal of the device 100 with the input terminal via the IGBT. Equivalent types of semiconductor switching elements other than IGBT elements may also be used, including but not limited to equivalent types of semiconductor switching elements such as metal oxide semiconductor field effect transistor (MOSFET) elements, bipolar transistor elements, silicon controlled rectifier elements (sometimes referred to as semiconductor thyristors), etc. The number of semiconductor switching elements may be changed to be greater than or less than Figure 2 Quantity shown.

[0069] The varistor element 146 connected in parallel to each pair of IGBTs in the illustrated arrangement exhibits a relatively high resistance when exposed to a normal operating voltage, and exhibits a much lower resistance when exposed to a larger voltage (such as associated with an overvoltage condition). When the varistor is operated in a low impedance mode, the impedance of the current path through the varistor 146 is significantly lower than the impedance of the IGBT, otherwise it is significantly higher than the impedance of the IGBT. This means that under normal conditions, the high impedance of the varistor causes all current to flow through the IGBT. However, as an overvoltage condition occurs, the varistor switches from a high impedance mode to a low impedance mode, and shunts or diverts the overvoltage induced current away from the IGBT to the load side circuit 136. As the overvoltage condition weakens, the varistor can return to a high impedance mode. The varistor advantageously allows, for example, a motor inrush current to flow through the device 100, while additionally allowing the IGBT to respond to an overcurrent condition after the motor start is completed. However, in other applications, the varistor 146 may be considered optional and may be omitted.

[0070] While an exemplary solid-state switch arrangement is shown and described, other arrangements are possible to implement solid-state switch functions in an arc-free manner.As described above, solid-state switch devices avoid the type of arcing produced by mechanical switches, thereby avoiding such arcing as a possible ignition source.

[0071] Figure 3 is a block diagram of a circuit protection device 100. The device 100 includes a processor-based microcontroller, which includes a processor 150 and a memory device 152, in which executable instructions, commands and control algorithms and other data and information required for the proper operation of the device 100 are stored. The memory 152 of the processor-based device can be, for example, a random access memory (RAM), as well as other forms of memory used in conjunction with RAM memory, including but not limited to flash memory (FLASH), programmable read-only memory (PROM), and electrically erasable programmable read-only memory (EEPROM).

[0072] As used herein, the term "processor-based" microcontroller shall refer not only to controller devices including processors or microprocessors as shown, but also to other equivalent elements, such as microcomputers, programmable logic controllers, reduced instruction set (RISC) circuits, application-specific integrated circuits and other programmable circuits, logic circuits, their equivalents, and any other circuits or processors capable of performing the functions described below. The processor-based devices listed above are exemplary only and are not intended to limit the definition and / or meaning of the term "processor-based" in any way.

[0073] The device 100 further comprises sensors 154, 156, 158 provided with numbers 1 to n, wherein n is equal to the number of switching poles in the device 100. Thus, for Figure 1 and Figure 2 The three-pole device 100 shown may include three sensors of each type, which detect current, voltage and temperature at corresponding locations in the device to evaluate the actual operating circuit conditions in the device. In other embodiments, each switch pole may optionally be provided with an additional temperature sensor for enhanced temperature monitoring at multiple locations in each pole. Sensors 154, 156 and / or 158 in turn provide input to the processor 150. Therefore, with the help of sensors 154, 156 and / or 158, the processor 150 has real-time information about the current through each of the solid-state devices 162 numbered 1 to n, where n is equal to the number of switch poles in the device 100.

[0074] The detected current is monitored and compared to a baseline current condition, such as a time-current curve or trip signature programmed and stored in the memory 152 or the trip unit 160. By comparing the detected current to the baseline current condition, a decision can be made by the processor 150 to control the solid-state switching device 162 by controlling the output voltage to the gate-emitter voltage in the IGBT as described above, thereby stopping the conduction of current to protect the load side circuit from the destructive current. In some embodiments, the trip unit 160 enables a user to select settings for the operation of the trip unit 160 and change the time-current response of the device 100 within predetermined limits. In one example, the user can select a current rating for the device 100 at values ​​from 50A to 100A, and the trip unit 160 applies the appropriate time-current curve or time-current signature for the selected current rating.

[0075] The detected voltage can also be monitored and used as a basis for making control decisions, such as whether to operate the solid-state switching element 162 to protect the load-side circuits and components from adverse operating conditions. Since voltage and current are related, the detected voltage can be compared with the detected current to facilitate assessment of the health of the device 100, identification of errors, and to facilitate diagnostics and troubleshooting of the power system. As other fail-safe measures, voltage and current can be calculated from the sensed parameters and compared to sensor feedback to detect error conditions.

[0076] The sensed temperature can also be monitored and used to make control decisions about whether to operate the solid-state switch element 162 to protect the load-side circuits and components from adverse operating conditions. In addition, the sensed temperature can ensure that the conductors in the device 100 are operated below the rated temperature of the particular hazardous location in which they are located. For example, if the rated temperature is 200°F, when the operating temperature indicated by the temperature sensor rises to a temperature close to 200°F that could ignite airborne gases, vapors, or substances in the hazardous location, the processor 150 can operate the solid-state switch 162 to disconnect and stop the flow of current.

[0077] The processor 150 is in communication with the input / output display 116 to provide feedback to the user and to accept input via the display 116 .

[0078] In the example shown, the processor 150 receives line-side power through a power converter circuit 162. When it is necessary to provide direct current (DC) power to the processor 150 at a reduced voltage in a known manner, the power converter circuit 162 includes a step-down component and an analog-to-digital conversion component. Converting the line power to an appropriate level to power the electronic device avoids any need for a separate power source (such as a battery, etc.) or a separately provided power line for the electronic circuits and controls, which would otherwise be necessary. However, in some embodiments, such a separate power source may be included if necessary or desired. The described controls may be implemented on a circuit board in various arrangements of electronic packaging, and the algorithmic control features may be programmed and stored in the device memory.

[0079] Also included is a communication element 164 that can transmit data to a remote location to evaluate the operation of a larger power system. Wireless and non-wireless transmission of data of interest is possible, including but not limited to current data, voltage data (including waveform data), temperature data, on-off state data of solid-state switching elements, selected setting data, trip time data, etc., and such data can be stored and archived locally and remotely for analysis of the power system over time. The device 100 can also be remotely actuated via the communication element 164.

[0080] Although an exemplary architecture of apparatus 100 has been described, it should be understood that Figure 3 Certain elements shown may be considered optional to provide more basic functionality. In addition, additional elements may be added to make the operation of the device 100 more complete and intelligent, as well as to provide additional functionality beyond the circuit protection and disconnection functions.

[0081] Figures 4 to 8 Safety terminal assemblies for the apparatus 100 are shown, which establish electrical connections to line-side circuits and devices and load-side circuits and devices, either of which can be used as Figure 2The line side terminals 130a, 130b or 130c or the load side terminals 134a, 134b, 134c shown. The safety terminal assembly helps to reduce (if not eliminate) the problems associated with conventional terminals, which tend to loosen over time when subjected to thermal cycling, vibration or other harsh operating conditions in hazardous environments. Loose terminal connections can increase the resistance at the terminals and generate excessive heat during operation of the device. In some cases, such increased resistance or heat can degrade the connection to an extent that can lead to failures and arcs at the terminals. Therefore, there is a need for an improved terminal assembly that more safely secures and maintains the cable connection to the device 100 to reduce (if not eliminate) possible ignition sources caused by degradation of the cable connection in use. In addition, the improved terminal assembly can also be used to establish a secure electrical connection with the cable to establish auxiliary connections, input / output connections, etc. as needed or desired.

[0082] like Figure 4 As shown, the safety terminal assembly 180 includes a box ear 182 and a terminal fastener 184 (such as a screw). In the example shown, the box ear 182 defines an opening or hole 186 that receives the front end of the cable conductor along a first axis that extends to Figure 4 As shown, the box ear 182 also defines a threaded hole 188 formed on the upper surface of the box ear 182 to receive the fastener 184 along a second axis, the second axis being in the plane of the page. Figure 4 The vertical plane extends perpendicular to the first axis.

[0083] In use, a cable conductor for establishing a line-side connection or a load-side connection is received in the hole 186 of the box ear 182 along the first axis, and the head of the fastener 184 can then be rotated to advance the opposite end of the fastener 194 toward the cable conductor into the hole 186. Once the end of the fastener is in physical contact with the cable conductor in the box ear hole 186, further advancement of the screw fastener 184 will generate a clamping force that firmly holds the cable conductor in place in contact with the surface of the box ear 182 to complete the electrical connection.

[0084] To prevent the fastener 184 from loosening during subsequent operation of the device, a coil spring 190 extends around the shank of the screw fastener between the upper surface of the box ear 182 and the screw head. When the screw is tightened into contact with the cable conductor to establish the desired contact clamping force, the spring 190 essentially locks or clamps the screw and the box ear together. This locking of the fastener 184 in the desired position achieves a vibration-proof connection that prevents the connection from loosening over time between the cable connector and the terminal. In addition, the locking of the fastener 184 in the desired position avoids any tendency of the screw to loosen over time when subjected to thermal cycling. By ensuring a high quality terminal connection, Figure 4 The locking terminal assembly avoids excessive heat and / or arcing at the terminals and ensures that the operating temperature of the conductor bus structure and the terminals can be maintained within the appropriate temperature limits for the hazardous location designed for the device.

[0085] exist Figure 5 In the illustrated safety terminal assembly, an alternative locking element in the form of a spring plate 200 is provided around the box ear 182, as shown. When the fastener 184 clamps the cable conductor with the desired amount of contact clamping force, the spring plate 200 also effectively locks and clamps the screw and the box ear together, thereby achieving Figure 4 The coil spring 190 shown has a similar effect. Figure 5 The arrangement in omits the locking spring 190 supporting the spring plate 200, but the spring 190 and the spring plate 200 can be used in combination to lock and clamp the screw to prevent it from loosening.

[0086] Figure 6 A safety terminal assembly including a locking terminal arrangement is shown, which has another form of ear-shaped terminal 220 and a spring plate 222 extending only at the upper portion of the terminal 220. The spring plate 222 also effectively locks and clamps the screw and the ear-shaped terminal together, wherein the screw clamps the cable conductor with a desired contact force, thereby achieving an effect similar to that described above. Figure 6 The spring plate 222 in the terminal ear 220 realizes the locking effect at the position inside the terminal ear 220, and Figure 4 and Figure 5 The example of the terminal ear achieves a locking effect at a position outside the terminal ear. Of course, a combination of internal locking elements and external locking elements is possible, such as by including Figure 4 Spring 190 and Figure 6 The spring plate 202 is provided.

[0087] Although Figures 4 to 6 While exemplary geometries and locations of locking elements in the form of springs and spring plates are shown, other types and geometries of locking elements may also achieve the desired beneficial locking or jamming at the same or different locations to prevent the terminal connection from undesirably loosening during subsequent operation of the device. It should be understood that the locking effect described is sufficient to overcome any tendency of the connection to loosen due to exposure to vibration, thermal cycling, and other environmental requirements of hazardous locations. However, the locking effect described can be overcome without undue difficulty when it is necessary to facilitate a new connection or to completely remove the device 100 from the line-side circuit and the load-side circuit when necessary. Similarly, auxiliary circuit connections or other terminal connections formed with similar terminals can be overcome without undue difficulty when it is necessary to facilitate a new connection or remove the device 100 for repair or replacement.

[0088] Figure 7, another safety terminal assembly 230 is shown, which includes a terminal ear 232 and a rotatable rod 234 mounted to the terminal ear 232 so that the rod 234 can be rotated toward the cable conductor received in the terminal ear 232. A biasing element 238 such as a torsion spring is provided at one end of the rod 234 around the rotation axis of the rod to apply a desired contact force to the cable conductor and hold it in place in the terminal ear 232, thereby ensuring that the wire 236 is tightly fixed and will not loosen due to vibration or thermal cycling. The biasing element 238 holds and effectively locks the cable conductor in place under the action of force, thereby achieving the necessary vibration-proof connection that is not adversely affected by thermal cycling over time.

[0089] Terminal assembly 230 avoids the conventional fastener screws of previous assemblies, thereby providing additional benefits. Biasing element 238 achieves a consistent contact clamping force that is independent of the installer, while Figures 4 to 6 The fastener assembly may be tightened to different degrees by different people, and thus may result in some variation in the quality of the connection formed. The terminal assembly 230 (including the rod 234) can also be quickly and easily tightened by hand without the use of tools, while Figures 4 to 6 The fastener assembly of the present invention requires the use of a tool (e.g., a screwdriver) to achieve the desired locking. For the terminal assembly 230, the release of the cable conductor is also simplified because the user does not need to overcome the locking or jamming effect of the spring 190 or the spring plates 200, 202 to loosen the fastener 284, but can simply rotate the rod 234 with sufficient force to overcome the clamping force of the torsional biasing element 238 and then pull the cable conductor 236 from the terminal.

[0090] Figure 8 A further embodiment of a safety terminal assembly 240 is shown, which includes a terminal ear 242 and a fastener 244, which can be securely connected to a cable conductor via an arrangement such as described above. However, the terminal ear 242 is nested within a larger terminal housing 246 including a connection hole 248. A connector pin 250 can be received in the hole to complete an electrical connection with the terminal ear 242 in the housing 246.

[0091] It is worth noting that, unlike the previously described device 100 mounted to the housing 102 Figures 4 to 7Unlike the safety terminals of the present invention, the pin 250 is mounted to or protrudes from the housing 102 of the device 100 for insertion and removal from the terminal assembly 240 through the hole 248. In this way, once the cable conductor connection is made with the terminal ear 242, the device 100 can be removed, reinstalled or replaced without disturbing the cable conductor connection. A locking or latching element may be included to secure the pin 250 and / or the device housing 102 relative to the hole 248 and / or the terminal housing 246. Likewise, the ear 242 may be arranged in any suitable structure to secure the cabling used in hazardous locations.

[0092] Because the device 100 includes a solid-state switch, the pin 250 of the device 100 can be removed from the hole 248 after controlling the switch to ensure that no current flows through the device, eliminating any possibility of arcing and facilitating the desired "hot plug" function, wherein the device 100 can be removed while the line-side circuit remains "live" or energized. Alternatively, the solid-state switch can be controlled in response to a sensed parameter to limit the current when the pin 250 is removed, thereby reducing the arc discharge to a level that is insufficient to produce ignition problems in hazardous locations. When the pin 250 of the device 100 is inserted into the hole 248 to complete the electrical connection with the terminal ear 242 and the connected cable conductor, the solid-state switch element in the device 100 is also operable to limit the flow of current. With the pin 250 and hole 248 that achieve a plug-in connection, the benefit of the device 100 is that the electrical connection is made or broken within the hole 248, thereby safely protecting the user from electric shock when the device 100 is manually installed and removed. Particularly for switchboard installations including multiple devices 100 on a switchboard, the convenience of manual hot-swap installation and removal without disturbing cable conductor connections provides significant benefits in terms of time and labor costs for servicing the power system.

[0093] Although in the example shown, the device 100 includes pins 250 and the terminal assembly 240 includes holes 248, this can be effectively reversed in another embodiment. That is, the device 100 may include holes, and the terminal assembly includes pins, and the holes and pins will combine to achieve at least some of the above benefits. With respect to the terminal assembly including pins, appropriate measures should be taken to prevent the risk of electric shock caused by the exposed and energized part of the terminal pins. For example, an insulating cover or shielding member may be included in the terminal assembly, which surrounds the pins to prevent the user from contacting the pins when removing the device 100, but does not hinder the electrical connection with the device 100. Another exemplary safety measure may include a mechanical interlock and an additional switch, which can be manually or remotely operated to disconnect the terminal including the pins before the device 100 can be removed. Finally, the line side can be de-energized by the operation of an upstream switch or circuit protector to allow the device to be safely removed and replaced without causing the risk of electric shock to the user.

[0094]

[0063] Although exemplary types of male and female connector elements have been described, in other embodiments, alternative types and shapes of male and female connector elements may be provided in combination.

[0095] The terminal assembly 240 also has an additional benefit in that it can be configured to implement an accept / reject feature of the device 100 to ensure that only compliant devices 100 with the appropriate rating can be installed. For example, different devices 100 with different ampacity ratings can have pins 250 of different diameters, and different versions of the terminal assembly 240 can have holes 248 of different diameters. In this way, and for example, a device 100 with an ampacity rating of 200A can be rejected by incompatibility of the pins 250 with the holes 248 of a terminal assembly 240 that is rated for 100A and connected to a 100A cable conductor, while a device 100 with an ampacity rating of 100A and a corresponding pin 250 can be received in the holes 248 of a terminal assembly 240 that is rated for 100A and connected to a 100A cable conductor. If a higher amperage device 100 is inadvertently installed, it will not respond to overcurrent which could cause overheating and possible failure of the 100A cable conductors, or even compromise the required circuit protection for the load side circuits, but by virtue of the accept / reject feature, human error in installing an incorrectly rated device 100 is eliminated. This can be of particular benefit in panelboard applications that include multiple devices 100 with different ratings that might otherwise be confused.

[0096] Although one type of acceptance / rejection feature is described and shown as including cylindrical pins and holes, many variations are possible in this regard. Pins and holes of different geometries and shapes and different sizes can be provided to distinguish devices 100 with different ratings of different acceptance / rejection features. For example, a first group of devices 100 may be provided with square pins, a second group of devices 100 may be provided with round pins, and a third group of devices 100 may be provided with octagonal pins, etc. The terminal assembly 240 may also have square, round and octagonal holes. The size of the square, round and octagonal holes and pins may also be changed to provide the installer with unique acceptance / rejection features and visual cues to select and install the correct device 100 in any given device to ensure that the device is compatible with the existing wiring that cooperates with each type of terminal assembly 240.

[0097] On the other hand, the terminal assembly 240 can advantageously be used as an acceptance / rejection feature to ensure that a given device 100 is connected to the line side circuit and the load side circuit with the proper polarity. That is, the shape and / or size of the pins and holes defining the male and female connectors can vary on the line side and the load side of the device 100 to ensure that the device can only be installed with the proper polarity and the proper orientation, and cannot be installed in the opposite orientation, where the load side terminal of the device 100 is inadvertently connected to the line side circuit. In such an orientation, the device is substantially error-proof because incorrect installation is prevented. Therefore, and for example, the line side pin 250 of the device 100 may have a larger diameter than the load side pin 250 of the device 100, so that the line side pin can only be received in the line side hole 248 of the line side terminal assembly 240 having the hole 248 of the larger diameter. Therefore, an incorrect attempt to insert the line side pin 250 into the line side terminal assembly 240 having the hole of the smaller diameter cannot succeed.

[0098] As another example, the line side pins 250 of the device 100 may be square pins, while the load side pins 250 of the device may be cylindrical pins, which may provide a more intuitive polarity-related visual cue for the correct installation of the device 100, and the terminal assembly 240 includes square and cylindrical holes 248, respectively, and the size of the holes is set to prevent any attempt to install the device 100 with the opposite polarity. As another example, the line side of the device 100 may be provided with a male pin connector, while the load side device may be provided with a female hole connector, thereby again providing a visual cue to the installer, which may avoid any attempt to incorrectly install the device with the opposite polarity. In addition, the pins or holes / receivers may include multiple sections to improve contact engagement, reduce resistance, and ensure further integrity of the electrical connection to prevent degradation.

[0099] In another embodiment, color coding and marking features, etc., may also be utilized on portions of the device housing 102 and the terminal housing 246 to visually prompt the installer user how to properly install the device 100, and thus facilitate proper installation of the device 100 in a distribution board or other equipment having devices 100 of different ratings. For example, black and red may indicate the line side and load side of the device 100, and black and red may indicate the line side and load side of the terminal assembly, so that the installer can correctly install the device 100 according to the color. Positive and negative symbols + and – may also be used to determine the line side connection and load side connection of the device 100 and the terminal assembly 240. Color coding, markings, and symbols may be combined with the shape and pins and holes of the terminal assembly 240 to help reduce the likelihood that the installer will even attempt to install an incompatible device 100 or reverse the intended polarity of the device 100. Especially in hot-swap applications that can be quickly removed and replaced and where the opportunity for human error is increased, providing appropriate accept / reject features to ensure compatibility and polarity of the appropriate device for installation is important for safely operating a large number of devices in hazardous locations. Human errors are avoided, while the ease and convenience of installing the power system and completing maintenance procedures are greatly improved.

[0100] Fig. 9 The thermal management features of circuit protection device 100 are schematically shown. Thermal management is important to effectively distribute the heat generated by device 100 in use and to keep the surface temperature of device 100 below the applicable temperature limit for the hazardous location to avoid any ignition potential. Managing surface temperature is a multifaceted effort balancing the following considerations.

[0101] The size and outer surface area of ​​the housing 102 can be varied to achieve a surface temperature target without exceeding the target under expected operating conditions, including normal conditions and overcurrent conditions of the power system. A larger housing 102 with a larger surface area will generally dissipate heat over a larger surface area and therefore run cooler than an otherwise similar device with a smaller surface area. It should be noted here that by including heat sink fins and a contoured surface of the housing, a larger surface area can be achieved without significantly increasing the package size.

[0102] From a thermal management perspective, the size and spacing of the conductors 260a, 260b, and 260c in the housing 102 of the device 100, which defines the connection between the line-side terminals 130a, 130b, 130c, the solid-state switch arrangement 140a, 140b, 140c, and the load-side terminals 134a, 134b, and 134c ( Figure 2 ) interconnected bus structure. For any given current flowing through the device, the larger conductors 260a, 260b and 260c will generate less heat than the smaller conductors.

[0103] Increasing the path length of conductors 260a, 260b, and 260c will cause these conductors to generate less heat than conductors with shorter path lengths. Fig. 9 The substantially straight conductors 260a, 260b, and 260c shown generate less heat.

[0104] The relative spacing between the conductors 260a, 260b and 260c affects the amount of heat generated by the device in use. As the spacing between the conductors increases, the thermal coupling of the conductors 260a, 260b and 260c will decrease.

[0105] The materials used to manufacture the housing can vary to achieve thermal management and operating surface temperature goals, as some materials exhibit better thermal properties for distributing and dissipating heat than others. For example, a particular polymer resin can be selected or customized and can also be processed to formulate a material that will improve the internal thermal properties of the housing 102 and the thermal properties of its outer surface area. Metal and plastic housing elements can be used alone or in combination to manufacture the housing 102. In some cases, the housing 102 can be partially or completely filled with dielectric materials, dielectric fillers, or other filling media that can control, absorb, or distribute heat within the interior of the housing and thereby reduce the surface temperature of the device 100 when in use.

[0106] The housing structure may also include specific features designed with heat distribution and heat dissipation in mind. More than one material may be provided or combined to provide additional thermal insulation and avoid thermal coupling in desired areas (such as between adjacent conductors 260a, 260b, and 260c). The wall thickness of the housing may be varied to provide a greater or lesser degree of heat dissipation in selected portions or areas where it is most needed. Pipes, channels, or pits may be formed to strategically capture the generated heat and direct it more efficiently to the desired location for dissipation. Heat sink materials and the like may be included to improve heat absorption and heat dissipation.

[0107] Finally, active cooling elements may be provided for circulating an inert gas or cooling fluid through various portions of the device 100 to improve the thermal performance of the device 100. Such active cooling elements may be inherently contained or provided externally, and may function individually and independently in each device 100, or may function collectively across multiple devices 100. As one example, in a switchboard application, cooling fans or pumps may circulate fluid in or around multiple devices 100 to effectively manage surface temperatures. Temperature sensors 158 ( Figure 3) can provide a feedback signal to the active cooling system to turn on when needed and off otherwise. Thermoelectric devices can also be deployed with a feedback loop with a load device to reduce the available current through the device (thereby reducing heat). Thermoelectric devices can be used as an alternative to the fan / pump cooling method described above.

[0108] As another thermal management feature, the solid-state switch devices 140a, 140b, and 140c may be encapsulated with a material strategically selected or otherwise formulated to improve the thermal performance of the switch devices 140a, 140b, and 140c and / or to improve heat dissipation and heat distribution in use. The encapsulation material of the solid-state switch devices 140a, 140b, and 140c may be the same or different than the encapsulation material included in the housing construction, and in particular, the goal is to control or limit the operating temperature of the silicon in the solid-state switch devices in normal circuit operation or in overcurrent conditions and electrical fault conditions to prevent overheating of the switch devices themselves or overheating of the housing 102.

[0109] The thermal management considerations described above may be implemented in a variety of different combinations, some of which may eliminate the need for other considerations. For example, active cooling elements may eliminate any need for passive heat sinks in a given device 100. As another example, if the geometry and form factor of the housing 102 are optimized and manufactured from high-performance polymers, it may eliminate the need for active cooling elements. Temperature sensing may also be used to implement a fail-safe shutdown of the device 100 when the temperature approaches or exceeds a selected threshold. That is, the semiconductor switch may be controlled to disconnect the load side and interrupt the flow of current, thereby preventing any further increase in surface temperature, which may be independent of whether there is an overcurrent condition or a fault condition that would cause the device to trip.

[0110] Fig.10 1 is a perspective view of a compliant hazardous environment arc-free circuit protection device 300 according to a second exemplary embodiment of the present invention. The circuit protection device 300 includes the housing 102 described above for the device 100, but omits the digital display 116 ( Figure 1 ).like Fig.10 As shown, a user can access a toggle switch 302 on the upper surface of the housing 102 to manually activate the device 300 between the "on" and "off" states, thereby connecting and disconnecting the load side of the device 300 from the line side. In other embodiments, a manual actuator other than a toggle switch can be used. In some cases, a display 116 can be provided in addition to or as a substitute for the toggle switch 302 or another manual actuator.

[0111] Similar to device 100, device 300 can interconnect line-side circuits or power circuits with electrical loads that operate via alternating current (AC) or direct current (DC). Device 300 as shown is configured as a circuit breaker and thus provides automatic circuit protection in response to predetermined overcurrent conditions, which can be selected by a user within a specific range and input into the device via a local or remote user interface, or otherwise preprogrammed into the device. Device 300 can operate according to a specified time-current characteristic suitable for providing adequate protection for the connected load, including but not necessarily limited to the characteristics required as a UL 489 circuit breaker in the contemplated embodiment.

[0112] Fig.11 1 is a simplified schematic diagram of a circuit protection device 130 in an exemplary hybrid configuration. Device 300 includes input terminals 130a, 130b, 130c, each connected via connecting cables, conduits or wires to one phase of a three-phase power source indicated as line-side circuit 132. Device 300 also includes output terminals 134a, 134b, 136c, each connected to a load-side circuit 136, such as motors, fans, lighting fixtures and other electrical equipment in an industrial facility where ignitable gases, vapors or substances may be airborne as indicated at 138.

[0113] Between each pair of input terminals 130a, 130b, 130c and output terminals 134a, 134b, 136c are mechanical circuit breakers 304a, 304b, 304c and solid-state switch devices connected in parallel, the arrangements of the solid-state switch devices being shown as 140a, 140b and 140c. The exemplary solid-state switch arrangements 140a, 140b, 140c include pairs of insulated gate bipolar transistors (IGBTs) connected in series, wherein, as described above, each pair includes a varistor element connected in parallel to the IGBT. Although exemplary solid-state switch arrangements are shown and described, other arrangements may also implement solid-state switch functions in an arc-free manner. As described above, the solid-state switch devices operate in an arc-free manner, so there is no risk of ignition of the solid-state switch devices themselves in hazardous environments in terms of arc discharge.

[0114] The combination of mechanical circuit breakers 304a, 304b, 304c and solid-state switch arrangements 140a, 140b, and 140c can improve the response time of the device 300 relative to the device 100. However, the mechanical circuit breakers 304a, 304, 304c operate in conjunction with mechanical switch contacts, and therefore require special attention in hazardous location applications because arc discharge can be an ignition source. The solid-state switch arrangements 140a, 140b, and 140c connected in parallel to the mechanical circuit breakers 304a, 304b, 304c can limit the current in the mechanical circuit breakers 304a, 304, 304c in an overload or short circuit event to reduce the intensity of any arc that is generated to a level below that required to cause ignition problems or otherwise completely eliminate arc discharge.

[0115] Fig.12 1 is a block diagram of a circuit protection device 300, which, in addition to the above-mentioned elements in the device 100, also includes a control input for a manual actuator 302 and a trip actuator 310 for operating a mechanical circuit breaker 312 including a mechanical switch. When a predetermined overcurrent is detected, the trip unit 160 causes the trip actuator 310 to shift the active switch contact and disconnect the circuit through the device 300. The trip actuator can be an electromagnetic member, such as a solenoid, which can simultaneously shift the switch contact of each mechanical contact provided in the device 300, wherein the solid-state switch arrangement 140a, 140b and 140c limits the current when the switch contacts are shifted. Thereafter, the manual actuator 302 can be used to reset the device 300 by closing the mechanical contacts.

[0116] While an exemplary architecture has been described, it should be understood that Fig.12 Certain elements shown may be considered optional to provide more basic functionality, and additional elements may be added to make the operation of the device 300 more sophisticated and intelligent.

[0117] Fig.13 It shows schematically Figures 10 to 12 Thermal management features of the circuit protection device shown. While hybrid device 300 is capable of operating in an arc-free manner as described above, additional considerations must be taken to account for any arcing that occurs because arcing may depend on the nature of the electrical fault and the voltage and current of the operating power system when the electrical fault occurs.

[0118] like Fig.13 As shown above, in addition to Fig. 9 In addition to the thermal management features described for device 100 , device 300 includes additional features to ensure that any arcing that occurs during operation of the mechanical circuit contacts is isolated from the surrounding environment or otherwise reduced to levels insufficient to cause ignition in hazardous locations. Fig.13The housing 102 of the device 300 is shown, which defines a first or primary enclosure 320 and a series of secondary enclosures 322a, 322b, 322c. The secondary enclosures 322 are used to contain any arc within the secondary enclosure while ensuring that airborne ignitable gases, vapors or substances cannot reach the secondary enclosures 322a, 322b, 322c and therefore cannot be ignited by the operation of the mechanical switch contacts.

[0119] In the envisioned embodiment, the secondary housings 322a, 322b, 322c may be hermetically sealed chambers that include the respective switch contacts. The hermetically sealed chambers 322a, 322b, 322c are fluid-tight so that any ignitable elements that may penetrate the housing 102 into the hazardous location of the device housing 102 cannot enter the sealed chambers 322a, 322b, 322c. The hermetically sealed chambers may also be vacuum chambers or filled with an inert gas so that even if arcing is not completely avoided when the switch contacts are opened and closed, the intensity and duration of the arcing will be reduced. Each of the secondary housings 322a, 322b, 322c may be provided with additional insulators and materials to control any heat associated with arcing and locate it to the secondary housings 322a, 322b, 322c within the larger housing 320. The housing within the housing construction of the housing 102 accommodates the other thermal management features described above while addressing the additional issues of mechanical switch contacts in hazardous locations.

[0120] The secondary housing 322a, 322b, 322c may be made of a material different from the rest of the housing 102, or may be made of a combination of materials that may be the same or different from the rest of the housing. For example, metal materials and plastics may be used to construct the chamber, while the rest of the primary housing and the housing may be completely plastic. There may be many variations in this regard. The secondary housing 322a, 322b, 322c may be prefabricated and assembled with the housing 102 in a separate manufacturing stage. The secondary housing 322a, 322b, 322c may surround some or all of the mechanical circuit breaker mechanism without obstructing the movement path of the switch contacts or their ability to move. Encapsulating materials and filling materials may be provided on the inner and outer surfaces of the secondary housing 322a, 322b, 322c to provide further changes in thermal performance, and similarly, without obstructing the movement path of the switch contacts or their ability to move, to ensure a reliable circuit breaker function when manually actuated, so as to facilitate maintenance of the power system or automatically protect the electrical loads connected by the device 100.

[0121] Either device 100 or 300 can be safely used in IEC Zone 1 hazardous locations and NEC Division 2 hazardous locations without the need for an explosion proof enclosure. The above-described built-in anti-ignition features eliminate ignition sources or reduce them to a level insufficient to cause ignition. Therefore, the device 100 or 300 is sometimes referred to as being ignition proof and thus eliminates any need for an explosion proof enclosure. Thus, the devices 100 and 300 prevent possible explosions that would otherwise be safely controlled by setting up a conventional explosion proof enclosure. Therefore, the devices 100 and 300 can be safely operated in hazardous locations and eliminate the cost and burden of conventional explosion proof enclosures while saving space in the power system.

[0122] Fig.14 An exemplary switchboard 400 including a compliant hazardous location arc-free circuit protection device is shown, the circuit protection device including an array of devices 402, 404 arranged as two columns of devices, wherein the devices 402, 404 are positioned side by side in each column. The devices 402, 404 in each column include the devices 100 and 300 described above, and the devices 402, 404 can be represented by different ratings, which provide different degrees of circuit protection for various different loads that are loads served by the switchboard and its various branches. The switchboard 400 typically includes its own enclosure, but the enclosure of the switchboard itself can be a standard environmental enclosure that is not designed to be explosion-proof. Because the devices 402, 404 are ignition-proof, they can be present in the switchboard enclosure without the need for a conventional explosion-proof enclosure in the switchboard enclosure. The switchboard enclosure protects the devices 402, 404 from environmental conditions, but with the ignition-proof devices 402, 404, there is no need to provide a separate explosion-proof enclosure for the switchboard. Considering that known switchboards can accommodate up to 84 devices, eliminating explosion proof enclosures significantly reduces the cost of operating devices in hazardous locations. For large power systems that include multiple switchboards located at different locations, the cost is even further multiplied. In contemplated embodiments, the switchboard 400 can also be a single integrated circuit device with multiple programmable channels to accommodate the desired combination of single-pole, two-pole, and three-pole circuits.

[0123] In such a switchboard installation that includes multiple devices 402, 404 operating simultaneously and in close proximity to each other, the thermal management problem is multiplied. Thermal effects can accumulate, and adjacent devices can run hotter (i.e., have higher surface temperatures) than when they are used alone or at least spaced farther apart from each other. As heat rises from the devices 402, 404 located below, the devices 402, 404 in the upper portion of the column can run hotter than the devices 402, 404 in the lower portion of the disclosure. In some cases, however, active cooling features and systems may be desirable to avoid undesirable temperature effects on the operation of some of the devices 402, 404 or to address elevated surface temperatures. As described above, an active cooling system may be provided on or relative to the switchboard to cool the devices 402, 404 at a system level rather than cooling the devices 402, 404 individually. Variations and combinations of active cooling elements and systems are possible to achieve different cooling effects.

[0124] While a switchboard and switchboard enclosure are described above for devices 400, 402, similar benefits may be realized in motor control centers and other locations in power systems where circuit protection devices 402, 404 are also located in non-explosion proof enclosures. Given the sensors and intelligence provided in devices 402, 404 and the motor inrush features provided in devices 402, 404, additional motor starting components may be integrated into the design of devices 402, 404 and a combination circuit protector / motor starter provided in a single package, as opposed to conventionally provided separately packaged and serially connected circuit protectors and motor starter assemblies, each of which requires an explosion proof enclosure for use in hazardous locations. Other dual use or dual function devices 400, 402 are also possible, which further reduce the cost of installing and servicing power systems by reducing the number of devices that need to be acquired, installed, and serviced in the power system.

[0125] Figure 15 to Figure 1 9 shows an additional circuit diagram of an exemplary solid-state device or hybrid device such as those described above. Fig.15 is an exemplary circuit diagram for a power electronic topology having a circuit protection device with a hybrid configuration. Fig.16 is an alternative solid-state switching device arrangement for a circuit protection device according to an embodiment of the present invention. Fig.17 Is used for Fig.16 An exemplary circuit diagram of a power electronic topology of a circuit protection device of a hybrid configuration is shown. Fig.18 is an exemplary circuit diagram of a power electronic topology for a circuit protection device having a solid-state configuration.

[0126] exist Figures 15 to 18 The circuit shown can be Fig.11 The solid-state switch arrangement shown here is implemented together with Fig.15 The circuit can be operated with minimal on-state losses. However, this may be disadvantageous from the perspective of low voltage arcing in the mechanical bypass switch when opening. It would be desirable to provide packaging materials and thermal management features for the bypass contacts.

[0127] Fig.16 and Fig.17 The arrangement and circuit shown are beneficial because the mechanical bypass switch can be opened when there is no current flowing, so arcing will not occur. Fig.16 and Fig.17 The arrangement and circuit shown generally require higher conduction losses, larger parts count, additional gate drivers, and greater complexity than other arrangements. Additionally, in some applications, Fig.16 and Fig.17 The arrangement and circuit shown may not easily meet the short disconnection time requirement.

[0128] Fig.18 The solid-state circuit shown advantageously includes no moving mechanical parts and can operate in an arc-free manner. It can also operate with a relatively simple switching algorithm, including soft starting of the motor when required. However, it operates with relatively high on-state losses.

[0129] Although various circuits and power electronic topologies have been shown and described, other circuits and power electronic topologies are possible and may be used in additional embodiments of devices in addition to or in place of the devices 100 and 300 that include the exemplary solid-state switch arrangements and hybrid switch arrangements shown and described above. The solid-state switch elements may be connected in series or in parallel using a modular arrangement to achieve a desired voltage rating scaling or a desired current rating scaling.

[0130] Any of the solid-state switch arrangements and hybrid switch arrangements shown and described above may include or be connected to line-side electrical fuses to enhance circuit protection reliability by addressing any deficiencies of the solid-state switch elements with respect to certain overcurrent conditions, or to improve response time to certain operating conditions.

[0131] The above-described arc-free operation, safety terminal assembly, and thermal management device can be easily applied to realize a circuit protection device that is not a circuit breaker device, but is still ignition-proof for use in IEC Zone 1 hazardous locations and NEC Division 2 hazardous locations without an explosion-proof enclosure. For example, the above-described fusible switch circuit breaker devices including a mechanical switch combined with a fuse can be realized with one or more of the above-described anti-ignition features, which makes them meet the requirements for use in hazardous locations. Applying the described arc-free operation, safety terminal assembly, and thermal management device, a solid-state fusible switch circuit breaker device or a hybrid fusible switch circuit breaker device can be easily constructed to have similar benefits, but provide different degrees of circuit protection.

[0132] Likewise, the above-described arc-free operation, safety terminal assembly, and thermal management device can be easily applied to realize a switch device that does not provide circuit protection itself, but is still ignition-proof for use in IEC Zone 1 hazardous locations and NEC Division 2 hazardous locations without an explosion-proof enclosure. For example, mechanical relay switches and contactors are known that provide a circuit-breaking function but do not have the ability to prevent overcurrent conditions. Applying the above-described arc-free operation, safety terminal assembly, and thermal management device, a solid-state relay device or a hybrid relay device and a solid-state contactor device or a hybrid contactor device can be easily constructed to have benefits similar to those described above.

[0133] Anti-ignition devices (such as those described) can be provided with any desired number of switching poles, such as only single-pole devices, two-pole devices, three-pole devices, and four-pole devices, to accommodate the needs of any type of power system (including single-phase power systems, multi-phase power systems, and multi-phase power systems), while generally providing anti-ignition functions for use in IEC Zone 1 hazardous locations and NEC Section 2 hazardous locations.

[0134] According to the above description, the device and the applicable operation algorithm have been functionally described, and those skilled in the art can therefore implement the algorithm via programming of a controller or other processor-based device. Such programming or implementation of the concept is considered to be within the scope of those skilled in the art and will not be further described.

[0135] It is now believed that the benefits and advantages of the inventive concepts have been fully demonstrated in accordance with the disclosed exemplary embodiments.

[0136] An embodiment of an anti-ignition switch device has been disclosed, the anti-ignition switch device comprising: a housing; a line-side terminal and a load-side terminal, the line-side terminal and the load-side terminal being connected to the housing; a bus structure, the bus structure being in the housing and comprising at least one solid-state switching element, the at least one solid-state switching element being capable of operating in an arc-free manner to connect the load-side terminal to the line-side terminal and disconnect the load-side terminal from the line-side terminal; and a controller, the controller operating the at least one solid-state switching element with reference to a first operating temperature limit of the bus structure, thereby preventing the operating bus structure from becoming an ignition source in a hazardous location, whereby the anti-ignition switch device is compliant for use in the hazardous location without the need for a separately provided explosion-proof enclosure.

[0137] Optionally, the housing is constructed and designed to operate at a surface temperature equal to or lower than a second temperature limit, and the controller is further configured to operate the at least one solid-state switch element with reference to the second temperature limit, thereby preventing the housing from becoming an ignition source in the hazardous location. The anti-ignition switch device may also include at least one mechanical switch contact in the bus structure, wherein the housing includes a sealed internal housing, the sealed internal housing accommodating the switch contact, thereby preventing the switch contact from becoming an ignition source in the hazardous location.

[0138] The line side terminal and the load side terminal each include a safety cable terminal assembly, the safety cable terminal assembly including a locking element, the locking element preventing the cable terminal from loosening over time when subjected to thermal cycling or vibration, thereby preventing the terminal assembly from becoming an ignition source in the hazardous location. The safety cable terminal assembly may include an ear-shaped terminal, and the locking element may be a spring element. The ear-shaped terminal may include a fastener, wherein the spring element acts on the fastener to prevent the cable terminal from loosening. The spring element may act inside the box ear. The spring element may be one of a coil spring or a spring plate. The safety terminal assembly may also include a rod, wherein the spring element acts on the end of the rod.

[0139] The line side terminal and the load side terminal may include a plug or a socket connected to a cable. The plug or the socket may provide a rejection feature for an incompatible switch device. The controller may also be configured to operate the at least one solid state switch element to implement a hot swap feature of the anti-ignition switch device.

[0140] The anti-ignition switch device may include a display. The anti-ignition switch device may include a toggle switch, wherein the controller is further configured to operate the at least one solid-state switch element in response to the toggle switch. The anti-ignition switch device may also include an active cooling element or a passive cooling element. A varistor is connected in parallel to the at least one solid-state switch element. The controller may be configured to provide a motor starter and an overload control. The device may be configured as a solid-state circuit breaker, or may be configured as a hybrid circuit breaker.

[0141] This written description uses examples to disclose the invention, including the best mode, and also to enable those skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. An anti-ignition switch device, the anti-ignition switch device comprising: case; a line-side terminal and a load-side terminal, the line-side terminal and the load-side terminal being coupled to the housing; a bus structure in the housing and including at least one solid-state switching element operable in an arc-free manner to connect the load-side terminals to the line-side terminals and to disconnect the load-side terminals from the line-side terminals; and A controller operates the at least one solid-state switch element with reference to a first operating temperature limit of the bus structure to prevent the bus structure in operation from becoming an ignition source in a hazardous location, whereby the anti-ignition switchgear is compliant for use in the hazardous location without the need for a separately provided explosion-proof enclosure.

2. The anti-ignition switch device according to claim 1, wherein the housing is constructed and designed to operate at a surface temperature equal to or lower than a second temperature limit, and the controller is further configured to operate the at least one solid-state switch element with reference to the second temperature limit, thereby preventing the housing from becoming an ignition source in the hazardous location.

3. The anti-ignition switch device according to claim 2 further includes at least one mechanical switch contact in the bus structure, and the housing includes a sealed internal shell, which accommodates the switch contact to prevent the switch contact from becoming an ignition source in the hazardous location.

4. The anti-ignition switchgear of claim 1, wherein the line-side terminal and the load-side terminal each include a safety cable terminal assembly, the safety cable terminal assembly including a locking element, the locking element preventing the cable terminal from loosening over time when subjected to thermal cycling or vibration, thereby preventing the terminal assembly from becoming an ignition source in the hazardous location.

5. The anti-ignition switch device according to claim 4, wherein the safety cable terminal assembly further comprises an ear-shaped terminal, and the locking element is a spring element.

6. The anti-ignition switch device according to claim 5, wherein the ear-shaped terminal further comprises a fastener, and wherein the spring element acts on the fastener to prevent the cable terminal from loosening.

7. The anti-ignition switch device according to claim 6, wherein the spring element acts inside the ear-shaped terminal.

8. The anti-ignition switch device according to claim 6, wherein the spring element is one of a coil spring or a spring plate.

9. The anti-ignition switch device according to claim 5, wherein the safety cable terminal assembly further comprises a rod, and the spring element acts on an end of the rod.

10. The anti-ignition switchgear according to claim 1, wherein the line-side terminal and the load-side terminal comprise plugs or sockets connected to cables.

11. An anti-ignition switchgear according to claim 10, wherein the plug or socket provides a rejection feature for incompatible switchgear.

12. The anti-ignition switch device of claim 10, wherein the controller is further configured to operate the at least one solid-state switch element to implement a hot-swap feature of the anti-ignition switch device.

13. The anti-ignition switch device of claim 1, further comprising a display.

14. The anti-ignition switch device of claim 1, further comprising a toggle switch, wherein the controller is further configured to operate the at least one solid-state switch element in response to the toggle switch.

15. The anti-ignition switch device of claim 1, further comprising an active cooling element.

16. The anti-ignition switch device of claim 1, further comprising a passive cooling element.

17. The anti-ignition switch device of claim 1, further comprising a varistor connected in parallel to the at least one solid-state switching element.

18. The anti-ignition switchgear of claim 1, wherein the controller is further configured to provide motor starter and overload control.

19. The anti-ignition switchgear of claim 1, wherein the device is configured as a solid-state circuit breaker.

20. The anti-ignition switchgear of claim 1, wherein the device is configured as a hybrid circuit breaker.

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