Configurable modular hazardous location compliant circuit protection device, system and method

Abstract

The present invention provides a modular circuit protection device and a configurable switchboard system, which includes arc-free operation and thermal management features to provide safe operation in hazardous environments at a lower cost, and does not require conventional explosion-proof enclosures or separately provided enclosures connected in series, such as circuit breaker devices and starter motor contactors and controls.

Description

Background Art

[0001] The field of the invention relates generally to circuit protection devices, and more particularly to low-cost, configurable, modular implementations of hazardous environment compliant circuit protection devices having enhanced safety, flexibility, and functionality in hazardous locations.

[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. For such devices, output power can be selectively switched from a power supply 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 electrically isolate load-side electrical equipment from line-side power circuits, thereby protecting load-side equipment and circuits from other destructive overcurrent conditions in the power system.

[0003] Although known circuit breaker disconnect devices can be used to 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 market needs. Therefore, improvements are needed. 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 a first simplified schematic diagram of a circuit protection device in an exemplary solid-state configuration in conjunction with a single mechanical switching device.

[0009] Figure 5 is a second simplified schematic diagram of a circuit protection device in an exemplary solid-state configuration in combination with a plurality of mechanical switching devices.

[0010] Figure 6 Shown for Figure 4 An exemplary terminal assembly for a mechanical switching device is shown.

[0011] Figure 7 Shown for Figure 4 and Figure 5 An example terminal block assembly of a circuit protection device is shown in an example solid-state configuration.

[0012] Figure 8 It includes Figure 6 and Figure 7 A first partial front view of a distribution board with terminal assemblies shown.

[0013] Fig. 9 Is installed Figure 6 and Figure 7 The device shown Figure 8 A second partial front view of a switchboard is shown.

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

[0015] Fig.11 is in 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 It shows schematically Figures 10 to 12 Thermal management features of a circuit protection device are shown.

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

[0019] Fig.15 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device according to another exemplary embodiment of the present invention is shown, which is configured to simulate a time-current curve of an overcurrent protection fuse.

[0020] Fig.16 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device according to another exemplary embodiment of the present invention is shown, which is configured to simulate the time-current curve circuit protection of a motor circuit protector.

[0021] Fig.17 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device according to another exemplary embodiment of the present invention is shown, which is configured to simulate a thermal overload time-current curve of a motor circuit protector. DETAILED DESCRIPTION

[0022] 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.

[0023] I. Prior Art

[0024] 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. Such hazardous environments may only occur in, for example, refineries, petrochemical plants, grain silos, wastewater and / or treatment facilities, and other industrial facilities where unstable conditions are created in the surrounding environment, increasing the risk of fire or explosion. The temporary or continuous presence of flammable gases, flammable vapors or combustible dust or other flammable materials in the air poses a significant challenge to the overall safe and reliable operation of these facilities, including but not limited to the safe operation of the power system itself, and in some cases, conventional circuit protection devices may create ignition sources during normal operation and in the event of electrical faults. Therefore, based on the assessed probability of explosion or fire risk, many standards for the use of electrical products in explosive environments have been promulgated to improve safety in hazardous locations.

[0025] For example, Underwriter's Laboratories (UL) standard UL 1203 specifies the criteria 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. By incorporating appropriate explosion-proof and dust-ignition-proof enclosures, electrical equipment manufacturers can obtain UL certification that demonstrates compliance with the rating standards applicable to hazardous locations, and 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 UL standard UL 1203.

[0026] The National Electrical Code (NEC) generally classifies hazardous locations by Class and Section. Class I locations are those where flammable vapors and gases may be present. Class II locations are those where combustible dusts are present. Class III locations are those locations that are hazardous due to the presence of ignitable fibers or flyings. Class I, Section 1 covers locations where flammable gases or vapors may be present under normal operating conditions, under frequent service or maintenance operations, or where failure or misoperation of process equipment may also cause simultaneous failure of electrical equipment. Section 1 presents a greater risk of explosion than, for example, Section 2, where flammable gases or vapors are typically handled in closed systems, confined within suitable enclosures, or are typically prevented by active mechanical ventilation.

[0027] The International Electrotechnical Commission (IEC) also classifies hazardous locations as Zone 0, Zone 1, or Zone 2, which represent locations where the air carries flammable gases or vapors in quantities sufficient to produce an explosive or flammable mixture. As defined by the IEC, Zone 0 locations are locations where flammable gases or vapors are present in ignitable concentrations continuously or for long periods of time. Zone 1 locations are locations where flammable gases or vapors in ignitable concentrations may be present or may frequently be present due to repair or maintenance operations, or due to the leakage or possible release of flammable gases or vapors in ignitable concentrations, or are adjacent to Zone 0 locations from which ignitable vapors in ignitable concentrations may be transferred.

[0028] Because electrical devices, such as those described below, can be a source of ignition in certain circumstances, explosion-proof, flame-retardant, or ignition-proof enclosures are often provided in NEC Section 1 or Section 2 locations and / or IEC Zone 1 locations to contain electrical devices that pose an ignition risk. As used herein, the term "explosion-proof" or "flame-retardant" refers to an enclosure that is designed to contain an internal explosion of a specified flammable vapor-air mixture. In addition, the explosion-proof or flame-retardant enclosure must operate at a safe temperature relative to the surrounding air.

[0029] 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 load from the electrical fault condition 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.

[0030] 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

[0032] breaker

[0033] 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

[0035] Switch (mechanical)

[0036] 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]

[0037] Note that the switch can turn on but not turn off the short-circuit current. 2.2.1

[0039] Switchgear

[0040] Devices designed to connect or disconnect current in one or more circuits[441-14-01]

[0041] Note that a switching device may perform either or both of these operations.

[0042] As can be seen from the above definitions, the difference between a circuit breaker as defined in IEC 2.2.11 and a mechanical switch as defined in IEC 2.2.9 is their different capabilities for mechanically responding to abnormal circuit conditions. Specifically, a circuit breaker as defined in IEC 2.2.11 can mechanically disconnect a short circuit condition, whereas a mechanical switch as defined in IEC 2.2.9 cannot disconnect a short circuit condition. Therefore, electrical fuses are sometimes used in conjunction with the mechanical switches of IEC 2.2.9 to implement a fusible disconnect switch that can respond to a short circuit condition by operation of the fuse (i.e., disconnection of the fuse) rather than operation of the mechanical switch contacts.

[0043] 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:

[0044] Fuse: An overcurrent protection device with a fusible component that is heated and melted by the passage of overcurrent, thereby breaking the circuit.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] In contrast to the circuit protection devices described above, the "switching device" of IEC 2.2.1 as 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 disconnect 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 other than a circuit breaker device actually includes mechanical switch contacts, it may present an ignition risk when located in a hazardous environment.

[0049] 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 (i.e., 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 insufficient to isolate the arc from ignitable airborne elements. To this end, known devices including mechanical switch contacts are typically located in a separate explosion proof enclosure, which is then contained in the environmental enclosure, or the switching system (i.e., the switchboard) may then be installed in a single large explosion proof enclosure, without the need for a separate explosion proof enclosure for switching within a Section 1 location of the NEC to provide the necessary protection.

[0050] 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.

[0051] Available explosion-proof, flame-retardant or ignition-proof enclosures effectively enable mechanical switching devices in NEC's Section 1 or Section 2 locations or IEC's Zone 1 or Zone 2 locations to operate safely, but generally bring additional costs, occupy valuable space in the power system, and add a certain burden to the installation and maintenance of the power system over time. Access to the circuit breaker within the explosion-proof enclosure usually requires time-consuming removal of multiple fasteners, and after completing any maintenance procedures, 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 usually shut down (i.e., disconnected), and the related load-side processes are stopped to ensure safety during the maintenance procedure. From the perspective of industrial facilities, such downtime costs are high, and it is important to limit or shorten downtime. Therefore, in some cases, if the explosion-proof enclosure can be eliminated in the NEC's Section 1 location while still providing a safe circuit breaker function in a hazardous environment, this will be desirable. To this end, a circuit protection device designed to reduce the risk of ignition is required, but such a device is generally not currently available.

[0052] 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.

[0053] Solid-state switches advantageously eliminate arcing associated with the displacement of mechanical switch contacts as described above, but still create a possible source of ignition through 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 can rise to a point where autoignition occurs due to the flash point temperature of the specific gas or ignitable substance in the hazardous location.

[0054] The connection terminals of solid-state switching devices may also create reliability problems and possible ignition sources when used in Section 1 or Section 2 locations of the NEC or Zone 1 or Zone 2 locations of the IEC. More specifically, the terminals may tend to loosen over time when subjected to thermal cycling or vibration. Under certain operating conditions, loose terminal connections can lead to overheating and possible ignition sources (if not arcs) at the terminal locations. Poor quality terminal connections can also cause overheating of conductor structures (sometimes called buses) in the device, creating further ignition problems in hazardous locations. Therefore, if explosion-proof enclosures are not supplementarily used in Section 1 or Section 2 locations of the NEC or Zone 1 or Zone 2 locations of the IEC, the use of known solid-state switching devices alone (without other devices) does not ensure adequate safety in hazardous locations.

[0055] 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 mix 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 Division 1 or 2 locations or IEC Zone 1 or 2 locations.

[0056] II. Inventive No-Arc Devices, Systems, and Methods for Hazardous Location Compliance .

[0057] 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 1 or Division 2 locations of the NEC or Zone 1 or Zone 2 locations of the IEC without necessarily requiring a separately provided explosion-proof, flame-retardant, or ignition-proof enclosure. Thus, and via the elimination of such separately provided explosion-proof, flame-retardant, or ignition-proof enclosures, the exemplary circuit protection devices described herein may be implemented in power systems at reduced cost and with reduced amounts of space in electrical panels, control centers, and the like. The exemplary circuit protection devices described herein may be provided in a modular and configurable system that facilitates more economical installation, maintenance, and supervision of power systems. Some aspects of the method will be discussed explicitly and others will become apparent from the following description.

[0058] In a first aspect, an exemplary circuit protection device may be implemented in the form of a solid-state circuit protection device having arc-free operation in the switching of the device to connect or disconnect a load-side circuit through a solid-state switching device, incorporating an enhanced feature phase to address possible ignition sources at the wiring terminals, and / or including a thermal management feature to address possible overheating of conductive elements inside 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 applicable to NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations, and thus allow conventional explosion-proof, flame-retardant, or ignition-proof enclosures to be eliminated for certain applications.

[0059] In a second aspect, the exemplary solid-state circuit breaker device may also be configured as a modular device, thereby facilitating an economical and configurable switchboard system that can meet a variety of different circuit protection requirements for different power systems and electrical loads. The modular solid-state circuit breaker device may be used in combination with the modular mechanical switch device to ensure safe switching operation and improve response time under certain electrical conditions. Each modular solid-state circuit breaker device may be connected to more than one modular mechanical switch device in the modular mechanical switch device, and the current load through the modular mechanical switch device may be shared across the modular solid-state circuit breaker devices when necessary to ensure safe operation of the modular mechanical switch device.

[0060] In a third 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 may be further combined with enhanced features to: isolate the arc between the mechanical switch contacts from the surrounding environment to prevent ignition, and address possible ignition sources at the connection terminals and / or include thermal management features to avoid possible overheating of conductors in the hybrid device. Thus, unlike conventional hybrid circuit protection devices, such hybrid circuit protection devices comply with hazardous location standards applicable to NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations, and allow conventional explosion-proof enclosures to be eliminated for certain applications.

[0061] In a fourth aspect, a hybrid circuit protection device can be configured as a modular device to be easily installed in a switchboard while saving space. The modular device can also be configured to have additional built-in components and functions, such as motor starter components and associated functions integrated into the controls of the hybrid circuit protection device, thereby achieving additional space savings and costs by eliminating conventional and series-connected separately packaged circuit breakers and motor starter devices.

[0062] 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, 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 Section 1 or 2 locations of the NEC or Zone 1 or 2 locations of the IEC), the benefits of the concepts described are not necessarily limited to Section 1 or 2 locations of the NEC or Zone 1 or 2 locations of the IEC, 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.

[0063] Figure 1 1 is a perspective view of a compliant hazardous environment circuit protection device 100 according to a first exemplary embodiment of the present invention. 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 an optional 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.

[0064] The housing 102 of the device 100 is made of materials strategically selected or otherwise tailored to withstand all possible electrical operating conditions, and in particular all possible electrical fault conditions, including concurrent fault conditions that may be generated by a power system protected in a Section 1 or 2 location of the NEC or a Zone 1 or 2 location of the IEC.

[0065] To comply in a Section 1 location of the NEC or a Zone 1 or Zone 2 location of the IEC, the housing structure and housing materials must also be further formulated to provide sufficient strength to withstand vibration and impact forces that may occur in an explosive environment, as well as provide chemical resistance to withstand exposure to chemicals in an explosive environment that may otherwise adversely affect the integrity of the device 100. As used herein, "chemical resistance" refers to the strength of the housing material to prevent chemical attack or solvent reaction. Chemical resistance in the housing 102 is the opposite of chemical reactivity, which can cause undesirable chemical effects and / or may undesirably generate heat and increase the temperature of the housing 102 when the housing 102 is exposed to certain chemicals. Chemical resistance refers to the resistance of the housing 102 to corrosive or caustic materials in the environment, including but not limited to airborne gases and vapors, by virtue of having little or no reactivity to regulated chemicals. For the device 100, chemical resistance is important for all materials described herein and structures that contribute to hazardous location compliance.

[0066] UL 1203 defines a chemical test that can be applied to determine whether any formulation of candidate materials for housing 102 is chemically resistant to explosive environments. Specifically, the UL 1203 chemical test requires that the sample housing be made of the formulation of the candidate material according to the desired housing structure, and the sample housing is exposed to saturated vapor in the air for a long time within a predetermined time period, and the saturated vapor contains a variety of prescribed chemicals. The prescribed chemicals used for the UL 1203 chemical test include acetic acid, acetone, ammonium hydroxide, ASTM reference fuel C, ether, ethyl acetate, ethylene dichloride, furfural, n-hexane, methyl ethyl ketone, methanol, 2-nitropropane and toluene. Different sample housings are exposed to each chemical within a predetermined time period, and after being exposed to each chemical, the sample housing is inspected to ensure that the housing structure of the sample is not damaged or shows signs of degradation via, for example, discoloration, expansion, contraction, cracking, rupture, leaching or dissolution. The sample housing that passes the inspection is then subjected to a fracturing test and compared with the results of the fracturing test before being exposed to the chemicals. A sample casing complies with UL 1203 if the fracturing force of the chemically tested sample casing shows that the chemically tested sample casing can withstand at least 85% of the corresponding fracturing force tested prior to exposure to the chemical.

[0067] By virtue of its manufacturing materials, the housing 102 should also exhibit chemical compatibility with specific chemicals present in a given NEC 1 or 2 section location or IEC 1 or 2 zone location. Chemical compatibility refers to the stability of the housing when exposed to substances in hazardous locations. If the housing 102 reacts chemically with substances in the environment, it is considered incompatible. Therefore, in view of the number of different corrosive or caustic chemicals and substances used throughout the range of industrial facilities, it is still recommended to perform compatibility testing to confirm chemical compatibility. Different facilities involving different caustic or corrosive substances may require housings of different materials to solve the problems caused. If it is not practical to determine or economically provide a universally optimal housing or material formulation, strategic selection and customized formulation of housing materials may be required for some explosive environments. In some cases, the UL 1203 compliance of the housing can eliminate the need for chemical compatibility testing in the selected facility, so chemical compatibility testing can be considered optional.

[0068] The materials used to manufacture the housing 102 may also be strategically selected or otherwise formulated and formed with specific structures to achieve thermal management and surface temperature goals for the device 100 in operation. Some housing materials may exhibit better thermal properties for distributing and dissipating heat than other materials. For example, a specific polymer resin may be selected or customized and formulated or processed to achieve a housing 102 that will improve the thermal performance of the device 100 in use, both on the interior of the housing 102 and on its exterior surface area, while protecting the power system, so that the exterior surface area temperature is maintained at a level below the temperature that may be ignited in a Section 1 or Section 2 location of the NEC or a Zone 1 or Zone 2 location of the IEC.

[0069] For any given housing material, the shape and form factor (including size, profile, etc.) of the housing 102 may positively or negatively change the overall thermal performance and surface temperature. For example, for a given device rating and operating voltage and current of the power system, a housing with a larger external surface area will generally reduce the surface temperature in use compared to a housing with a smaller external surface area. The housing structure may be designed to optimize and balance the overall package size and configuration and thermal performance.

[0070] In some embodiments, the housing 102 may be made of a metal or metal alloy, a non-metallic insulating material (such as a high-strength, high-performance plastic), or a combination of metal and non-metallic materials to vary thermal performance and other considerations described above, namely, impact resistance and chemical resistance. Fully or partially encapsulated housing constructions are also possible. In some cases, the interior of the housing 102 may also be filled in whole or in part with a dielectric material, a dielectric fluid, a potting material, or other filling medium (such as sand) to contain, absorb, or dissipate heat and energy from the energized electrical conductors and switch components in the device 102, thereby ensuring that the surface temperature of the housing 102 will remain below the selected target temperature, thereby providing the device 100 with the desired thermal resistance level or temperature rating.

[0071] In addition to the materials used in its manufacture, the structural design of the housing 102 can also consider heat distribution and heat dissipation. The housing can be strategically configured to include more than one housing material in the entire housing 102 or at a specific target position in the housing. The housing substructure can be independently manufactured and provided for assembly to provide additional thermal insulation or thermal conductivity in the desired area of ​​the housing, so that heat is selectively limited and distributed in the selected position in a strategic manner. Similarly, the wall thickness of the housing 102 can be changed to provide a greater or lesser degree of thermal conductivity and heat dissipation in the selected part of the structure or in certain areas of the housing structure at the most desired position. Pipes, channels or pits can be formed to strategically capture the generated heat and guide it to the desired position more effectively for dissipation. Heat dissipation materials, etc. can be included to improve heat absorption and heat dissipation.

[0072] Active cooling elements are also possible, where a cooling fluid flows over or through the housing structure, and the housing structure includes appropriate structures to facilitate active cooling. The active cooling elements may be self-contained or provided separately, such as in a switchboard application where multiple devices 100 may be provided, the active cooling system counteracts the accumulated heat generated in the closely positioned devices 100 and mitigates the temperature impact that the devices 100 may have on each other. The active cooling system may include cooling fans or pumps that circulate fluid in or around multiple devices 100 to effectively manage surface temperatures. Including temperature sensor 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).

[0073] The above thermal management considerations can be implemented in various different combinations, some of which can offset or eliminate the need for other considerations. For example, in some applications, active cooling can eliminate the need for certain features of the housing, such as more complex shapes and form factors for dissipating heat over relatively complex surface areas.

[0074] The lateral sides 108, 110 of the housing 102 each include a connection recess 118, 120, 122 for connecting to the line-side circuit and the load-side circuit, respectively. Figure 1 In the example shown, three connection recesses 118, 120, 122 are provided for connection to a three-phase power source on one of the sides 108, 110, respectively, and to a three-phase load-side device on the other side. The power source and the load can each be operated with alternating current (AC) or direct current (DC). The device 100 as shown is configured as a circuit breaker and thus provides automatic circuit protection in response to a predetermined overcurrent condition, which can be selected by a 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 adequate protection for the connected load.

[0075] The display 116 may be a multi-function display to display different screens in response to user activation. In some embodiments, the display 116 may be touch-sensitive, and the user makes a selection by touching the selected area of ​​the display in accordance with the prompt. An input selector (such as a button, a knob, etc.) may be provided separately from the display 116 for the user to interact with the display. An input selector (such as a toggle switch) may also be provided separately from the display 116 to serve as a manually operable on-off switch that can be manually operated intuitively by the user. In this case, the toggle switch may simulate a traditional toggle switch to change the state to "on" or "off", but there is no displacement of the mechanical switch contacts when doing so, because as described below, the device 100 does not include a mechanical switch. Alternatively, the on / off feature may be built into the display 116 for the convenience of the operator, thereby realizing a disconnect switch function for the connected load-side device.

[0076] Display 116 can be a multi-function display to display different screens in response to user activation. In some embodiments, display 116 can be touch-sensitive, and the user makes a selection by touching the selected area of ​​the display according to the prompt. Input selectors (such as buttons, knobs, etc.) can be provided separately from display 116 for user input related to the prompts or information presented on display 116. However, it should be recognized that in some embodiments, display or display array 116 can be considered optional and does not need to be included at all. In other embodiments, additional input / output elements can be provided, whether it is a display or other interface for local and remote interaction between the user and the device.

[0077] 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 a Figure 2 134a, 134b, 136c, each connected to a load side circuit 136, such as motors, fans, lighting devices and other electrical equipment in an industrial facility, where ignitable gases, vapors or substances may be airborne as indicated at 138. The output terminals 134a, 134b, 136c may also be connected to the electrical load via connecting cables, conduits or wires. 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, etc.

[0078] Solid-state switching devices as shown at 140a, 140b and 140c are arranged between each pair of input terminals 130a, 130b, 130c and output terminals 134a, 134b, 136c. The exemplary arrangement includes pairs of insulated gate bipolar transistors (IGBTs) 142a, 142b, 142c, 142d connected in series to each other in reverse, wherein each pair of IGBTs 142a and 142b and 142c and 142d includes a varistor element 144 connected in parallel to the IGBTs. The reversely connected IGBTs in each pair exclude reverse currents flowing from the load side circuit 136 to the line side circuit 132 through the IGBTs in a known manner.

[0079] The IGBTs 142a, 142b, 142c, 142d in each arrangement 140a, 140b, and 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 the 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 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. Semiconductor switching elements of equivalent types other than IGBT elements may also be used, including but not limited to 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.

[0080] The varistor element 144 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 and / or an electrical fault condition). When the varistor 144 is operated in a low impedance mode, the impedance of the current path through the varistor 144 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 144 causes all current to flow through the IGBT, but with the onset of an overvoltage condition, the varistor 144 switches from a high impedance mode to a low impedance mode and shunts or diverts the overvoltage induced current surge away from the IGBT to the load side circuit 136. As the overvoltage condition subsides, the varistor 144 can return to a high impedance mode. The varistor advantageously allows, for example, motor surge current to flow through the device 100, while additionally allowing the IGBT to respond to the overcurrent condition after motor starting is completed. However, in other applications, the varistor 144 may be considered optional and may be omitted.

[0081] As another thermal management feature, the solid-state switching devices (e.g., IGBTs) in each arrangement 140a, 140b, and 140c may be encapsulated with a material strategically selected or otherwise formulated to improve the thermal performance of the switching devices 140a, 140b, and 140c and / or to improve heat dissipation and heat distribution in use. The encapsulation material of the solid-state switching 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 switching devices in normal circuit operation or in overcurrent conditions and electrical fault conditions to prevent overheating of the switching devices themselves or overheating of the housing 102.

[0082] Although an exemplary solid-state switch arrangement is shown and described, other arrangements are possible to implement the solid-state switch function in an arc-free manner. As described above, the solid-state switch device avoids the type of arcing generated by mechanical switches, thereby avoiding such arcing as a possible ignition source in NEC Section 1 or 2 locations or IEC Zone 1 or 2 locations.

[0083] In view of the hazardous environments in which the device 100 is to be used, reliable termination of the line-side cables and the load-side cables to the input and output terminals is important, as loose connections may create heat and reliability issues, as well as possible ignition issues in hazardous locations. In NEC Section 2 locations or IEC Zone 1 or Zone 2 locations, the input and output terminals are accessible from the exterior of the housing 102. Locking terminal connection assemblies and spring-biased terminal assemblies may be used to receive and retain the ends of the respective cables while reducing any tendency for the cable connections to become loose over time. However, in view of some of the device intelligence and fail-safe features described below, such locking terminal assemblies and spring-biased terminal connectors may be considered optional in NEC Section 2 locations or IEC Zone 1 or Zone 2 locations in some cases.

[0084] In the 1st section of the NEC, the input terminals and the output terminals may also be enclosed in an additional housing portion to provide additional safety assurance. Such housing portions may be provided separately from the housing 102, or may be formed integrally as an extension of the housing 102 to isolate the input terminals and the output terminals from the explosive environment. In the envisioned embodiment, a removable cover element may be provided to access the input terminals and the output terminals and the complete electrical connection of the input terminals and the output terminals inside the housing of the housing portion. The line side and the load side cable connection may be further established, for example, via an armored cable or a cable gland, which provides entry protection, sealing and grounding to allow the line side cable or the load side cable to pass safely through the housing of each housing portion. When used with an armored cable, a grounding to earth path may be established via a cable gland. However, in all embodiments, the armored cable is not necessary and may not be used. The cable gland may also be used with a non-armored cable.

[0085] The housing 102 may be designed and manufactured with thermal management issues in mind to maintain surface temperatures below applicable limits for a given installation in a Section 1 location of the NEC, and in some embodiments, the housing 102 may be explosion proof in whole or in part, meeting applicable standards for hazardous locations, although the housing is relatively small and more economical than conventional larger and separately provided explosion proof enclosures, which would typically contain the entire circuit protection device. The housing 102 and any enclosures defined therein may also include a vacuum chamber, or may be filled with a dielectric fluid, dielectric material, or inert gas to reduce or hinder arcing at the terminal / cable interface or other locations in the housing. The device intelligence and fail-safe features described below provide additional assurance and safety to address ignition source issues in hazardous locations, and may make some of the aforementioned features optional for Section 1 locations of the NEC.

[0086] To address possible static charge buildup (which can cause a possible ignition source in NEC Section 1 locations), Figure 2 146. In short, static electricity is the result of an electromagnetic imbalance between negative and positive charges in an object. Charging of the surface of a housing can be caused by surface charge involving another object (especially insulating portions of the housing) or by charge induction to conductive portions of the housing. Surface charging can also occur during exposure to a high voltage DC power source, which will cause ions to attach to the housing surface.

[0087] Regardless of how surface charging actually occurs, the connection to ground 142 allows any charge buildup on the housing 102 to be safely dissipated without creating an ignition source in the flammable / hazardous area. The housing 102 may be grounded to earth ground or chassis ground via a line wire or line conductor that is connected to the outer surface of the housing 102. Thus, any charging on the exterior of the housing 102 will quickly dissipate to ground as an electrical current and avoid high voltage discharge events that typically manifest as sparks or shocks that may be generated by a person or by tools used by a person in the presence of an explosive atmosphere and lead to ignition.

[0088] The housing 102 itself may also be made of an antistatic polymer or antistatic material in whole or in part, which is weakly conductive from the perspective of charge accumulation, but is still considered to be insulating and non-conductive from the perspective of the power system protected by the device 100. In the first case, relative to non-antistatic materials, antistatic materials can improve housing performance by reducing any tendency of the housing to be charged, and this is another consideration for strategically selecting or otherwise formulating one or more materials to be used for housing manufacturing. If necessary, an antistatic coating, encapsulation or shell can be provided on the outer surface of the housing, but chemical resistance and compatibility must still be ensured as described above. When the device 100 is directly connected to the housing / system grounding layer in the actual installation, due to mechanical attachment and / or physical proximity to the grounding layer, a dedicated grounding conductor for solving static problems may not be necessary.

[0089] Although Figure 2100, more than one ground connection may be provided at any desired location in the structure of the device 100. In addition to or as an alternative to grounding conductors connected to the exterior of the device housing 102 as described above, grounding conductors may be provided inside the device housing 102. When the line-side and load-side connections to the terminals 130a, 130b, 130c of the device 100 are made using armored cables that already include a ground path to earth, the ground connection for the housing 102 may also be established via a cable connector, such as a cable gland. Of course, in some cases, non-armored cables with or without cable glands may be used while still eliminating ignition sources in the device 100 and addressing static issues through alternative ground connections.

[0090] In NEC Section 2 locations or IEC Zone 1 locations, the device 100 will typically be protected by an enclosure and will therefore be less susceptible to static electricity issues and discharge events. Thus, in a device 100 used in NEC Section 2 locations or IEC Zone 1 locations, a connection to ground 146 may or may not be necessary or desirable, and may therefore be considered optional. However, with the device 100, the enclosure containing one or more devices 100 need not be explosion proof, and the conventionally provided explosion proof enclosure may be omitted.

[0091] 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).

[0092] 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.

[0093] 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.

[0094] The detected current is monitored and compared to a baseline current condition, such as a time-current curve 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 element 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 from the destructive current. In some embodiments, the trip unit 160 allows the 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. As one such example, the user can select the current rating of the device 100 at a value from 50A to 100A, and the trip unit 160 applies the appropriate time-current curve for the selected current rating.

[0095] The detected voltage can also be monitored and used to make control decisions on 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 diagnosis and troubleshooting of the power system. As other fail-safe measures, voltage and current can be calculated from the sensed parameters and compared with sensor feedback to detect error conditions.

[0096] The sensed temperature may 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. Additionally, the sensed temperature may ensure that the conductors in the device 100 are operated below the rated temperature for the particular hazardous location in which they are located. For example, if the rated temperature is 200°F, the processor 150 may operate the solid-state switch to disconnect and stop the flow of current when the operating temperature indicated by the temperature sensor rises to a temperature approaching 200°F that could ignite airborne gases, vapors, or substances in a Section 1 or 2 location of the NEC or a Zone 1 or 2 location of the IEC.

[0097] 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 .

[0098] 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 one or more circuit boards in various arrangements of electronic packages, and the algorithmic control features are programmed and stored in the device memory.

[0099] Also included is a communication element 164 that can transmit data to remote locations and other devices 100 as further described below to evaluate the operation of the larger power system in local and remote locations relative to any particular device 100. 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.

[0100] 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.

[0101] Figure 4is a first simplified schematic diagram of circuit protection device 180 in an exemplary solid-state configuration, combined with mechanical switching device 182, and completing a respective circuit path interconnecting line-side power circuit 132 and load-side circuit 136 and associated electrical loads.

[0102] Device 180 is similar to device 100 described above, and thus includes housing 102 and its features described above. Unlike device 100, which is shown as a three-pole circuit protection device having three switchable paths through the above-described solid-state switching elements, device 100 is a single-pole device and thus has only one solid-state switchable path via one solid-state switch arrangement 140. Similar to device 100, device 180 features housing construction, thermal management features, and arc-free switching features to address possible ignition issues in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations, and thus, device 180 can be used in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations without the need for a conventionally provided separate explosion-proof enclosure.

[0103] exist Figure 4 In the example of , the mechanical switch device 182 also includes a protective housing 186 and a single switchable path defined by a set of mechanical switch contacts 188. Therefore, the mechanical switch device 182 is a single-pole switch device, which in normal operation can complete the connection with, for example, only a single-phase motor on the load side of the device 182. In the contemplated embodiment, considering those thermal issues described above for the housing 102 of the device 100, the housing 186 is designed and constructed to have similar thermal issues to avoid ignition problems caused by excessive surface temperatures of the device 182 during operation.

[0104] In addition, the housing 186 may also include insulating materials, and an encapsulant may be provided in the housing 186, and the housing 186 may include a housing or chamber to physically isolate the switch contacts from the surrounding environment, so that if any arc discharge occurs at the switch contacts when the mechanical switching device 182 is opened and closed, it cannot ignite gases or vapors in the surrounding environment. The device 182 may also include a hermetically sealed housing construction, a vacuum chamber for suppressing any tendency of arc discharge, or a vacuum chamber filled with an inert gas, etc. to suppress or restrain the arc discharge and intensity to the greatest extent possible. In view of this construction of the housing 186, the mechanical switching device 182 can also be safely used in hazardous locations (such as NEC Section 1 or Section 2 locations or IEC Zone 1 or Zone 2 locations) without the need for conventionally provided explosion-proof enclosures.

[0105] The solid-state switch device 180 connected in parallel to the mechanical switch device 182 beneficially reduces arcing issues in the operation of the mechanical switch device 182 while improving the response time to certain operating conditions of the power system. In normal operation of the power system, the mechanical switch device 182 is normally closed to power the electrical load 136. The solid-state switch device 180 is normally open or non-conductive in normal operation of the power system, so that all current flows through the mechanical switch device 182.

[0106] In the event of an overcurrent condition or electrical fault condition that may be detected by the above-described sensors, the solid-state switch device 180 is controlled to close the solid-state switch to conduct current, thereby allowing current to flow in a parallel circuit path to the mechanical switch device 182. The current is split across the mechanical switch device 182 and the solid-state switch device 180, thereby reducing the current load on the mechanical switch device 182. The switch contacts 188 in the device 182 may then be opened, while reducing the likelihood of problematic arcing. The current load may be reduced to a level that is insufficient to cause arcing at the switch contacts 188 of the mechanical switch device 182, or the intensity of the arcing may be reduced to a lower level that does not pose an ignition problem to the operating mechanical switch device 182.

[0107] Likewise, during the switching of the mechanical switching device 182 in normal operation, the solid-state switching device 180 may be pre-controlled to switch on and reduce the current load for the switching of the mechanical switching device 182, thereby reducing any likelihood of arc discharge, or reducing the intensity of arc discharge. Alternatively, sensors in the solid-state switching device 180 may detect current and voltage conditions when the mechanical switching device 182 is disconnected, again conducting current in the parallel circuit path, and reducing the current load and voltage across the mechanical switch contacts 188 to suppress or avoid arc discharge conditions.

[0108] Figure 4 A first simplified schematic diagram of an exemplary hybrid circuit protection device is shown, which includes a one-to-one correlation of a solid-state switch device 180 and a mechanical switch device 182. The solid-state switch device 180 and the mechanical switch device 182 can be provided in various different combinations and connection schemes as a modular device further described below. Since the solid-state switch device 180 tends to be much more expensive than the mechanical switch device 182, a low-cost arrangement of the modular devices 180 and 182 is possible without safety or circuit protection performance.

[0109] Figure 5is a second simplified schematic diagram of an exemplary hybrid circuit protection device including a solid-state switch device 180 in combination with a plurality of mechanical switch devices 182. The mechanical switch devices 182 are arranged as a pair of devices, each of which defines a switchable path between a line-side power source 132 and a load-side circuit 136 and a corresponding electrical load, thereby defining in combination a two-pole switch device that can complete connection with, for example, only a two-phase motor on the load side of the device 182 in normal operation.

[0110] The solid-state switch device 180 is connected in parallel to each of the mechanical switch devices 182 and functions as described above. When controlled on and off, the solid-state switch device 180 either does not conduct current or shunts current across the mechanical switch device 182 and the solid-state switch device 180. Current may be shared across only one of the mechanical switch device 182 and the solid-state switch device 180, or may be shared between both the mechanical switch device 182 and the solid-state switch device 180, depending on the circuit conditions of each respective phase of the electrical power completed by these devices.

[0111] As long as solid-state switchgear 180 is capable of safely interrupting a simultaneous fault in each of the power system phases connected through switchgear 182, Figure 5 The layout in Figure 4 The one-to-one arrangement shown in provides safe operation at a lower cost. When applied to a two-phase load, the one-to-one arrangement requires two solid-state switch devices 180 and two mechanical switch devices 182. In contrast, Figure 5 The arrangement in is comparable to a single solid-state switch device 180 while still providing comparable safety and circuit protection performance. Again considering that the solid-state switch device 180 is much more expensive than the mechanical switch device 182, Figure 5 The arrangement involving a pair of mechanical switch devices 182 and a single solid-state switch device 180 represents a significant cost savings. In addition, Figure 5 The arrangement can be relative to, for example, Figure 4 The alternative one-to-one arrangement shown operates with reduced heat. The devices 180 and 182 may be provided as modular devices that may be interconnected (or not) as needed or as desired for the end-use application in a hazardous environment.

[0112] Figure 5The modular arrangement of the 100 can be expanded to include a third mechanical switch device 182 to power a three-phase electrical load, such as a three-phase motor. Assuming that the solid-state switch device 180 can safely handle simultaneous faults in the three phases, safe operation in NEC Section 1 or 2 locations or IEC Zone 1 or 2 applications can be ensured. Thus, three mechanical switch devices 182 and a single solid-state switch device 180 protecting a three-phase load represent an improvement over using an arrangement including three solid-state switches 100 ( Figure 1 ) is a significant cost saving. In this context, the device 100 is a multi-pole device, but for each pole there is Figure 4 One-to-one arrangement shown.

[0113] The modular arrangement can be further expanded to protect a 4-phase motor by adding a fourth mechanical switch device 182. If a single solid-state switch device 180 cannot safely handle simultaneous faults on all four phases, a second solid-state switch device 180 can be provided while still significantly reducing the cost over a one-to-one arrangement including three solid-state switch devices 180 and three mechanical switch devices 182.

[0114] On the other hand, similar arrangements and benefits can be achieved in other applications. For example, Figure 5 The dual mechanical switch to one solid state switch arrangement shown can be used to connect two discrete single pole circuits while safely handling simultaneous faults in each discrete single fault circuit connected through the device.

[0115] The modular concept presented above is generally scalable to accommodate as many or as many mechanical switch devices 182 as practical, combined with a minimum number of solid-state switch devices 180 to minimize cost while still providing safe operation and desired circuit protection in NEC Section 1 or Section 2 locations or IEC Zone 1 or Zone 2 locations. To summarize the above arrangement, for a power system having n phases, n mechanical switch devices 182 may be provided to power the desired electrical loads while being connected to less than n solid-state switch devices 180 to share the current load of selected ones of the n mechanical switch devices 182.

[0116] The modular concept is equally applicable to multi-pole switch devices. For example, a three-pole circuit protection device 100 can be connected to two or more three-pole mechanical switch devices 182, which has similar effects and cost savings as described above. In some embodiments, combinations of devices with different numbers of switch poles are also possible. For example, a four-phase electrical load can be connected by a three-pole solid-state device 100 and a single-pole solid-state device 180 connected in parallel to a three-pole mechanical switch device and a single-pole mechanical switch device. Similarly, a four-phase electrical load can be connected by a three-pole solid-state device 100 and a single-pole solid-state device 180 connected in parallel to a pair of two-pole mechanical switch devices. In this regard, multiple combinations can be achieved using modular devices with different numbers of switch poles.

[0117] Likewise, multi-pole switching devices need not be used with multi-phase power systems and multi-phase loads. The three-phase device 100 can be used in combination with three mechanical switching devices to power three single-phase loads. As another example, the three-phase device 100 can be used in combination with three mechanical switching devices to power a two-phase motor and, for example, a single-phase load (such as a fan) to cool the motor during operation while providing circuit protection for the motor and the fan. In this regard, modular devices with different numbers of switching poles can be used to interconnect power systems and electrical loads with different numbers of phases, thereby achieving multiple combinations.

[0118] Figure 6 A modular mechanical switch device 182 and a terminal assembly are shown that facilitate convenient interconnection to implement the modular circuit protection arrangement described above. Figure 6 In the example of FIG. 1 , the terminal post or pin 188 is shown protruding from the rear side of the device housing 186. The mechanical switch 188 ( Figure 4 and Figure 5 ) are connected between terminal posts or pins 188 in the mechanical switching device 182.

[0119] Terminals 190 and 192 are provided separately from the device 182 and include holes 194, 196, respectively, which receive the terminal posts or pins 188. The posts or pins 188 of the mechanical switch device 182 and the holes 194, 196 of the terminals 190, 192 define matching male and female connection features to complete the mechanical and electrical connection with and through the mechanical switch 188 of the device 182 and the terminals 190, 192, which in turn are connected to the line-side power source 132 and the load-side circuit 136 through the bus structure of the distribution board or through wires or cables in various different embodiments.

[0120] exist Figure 6In the example of FIG. 1 , the bus structure may also include a bus 1 connection 198 and a bus 2 connection 200, as shown in the figure, which respectively define conductive structures in the switchboard for connecting to one or more solid-state switch devices 180, thereby achieving the above Figure 4 and Figure 5 In a contemplated embodiment, the terminals 190, 192 may be secured to the bus structure of the panelboard, or may be secured in position on another support structure so that the mechanical switching device 182 may be selectively positioned relative to the terminals 190, 192 so that the mechanical switching device 182 may be removed and replaced without interfering with the connection of the terminals 190, 192 to the line-side circuit and the load-side circuit.

[0121] Figure 6 The male and female connection features shown are exemplary only. Although the mechanical switch device 182 is shown as having a male connector post and the terminals 190, 192 are shown as having female holes 194, 196, in another embodiment, this can be effectively reversed to provide a male connector on the terminal and a female connector on the mechanical switch device 182. The size and shape of the post and hole can also be changed to define the acceptance / rejection feature, thereby ensuring that only compatible devices can be used with compatible terminals, and also ensuring a one-way installation, which prevents inadvertent attempts to install the mechanical switch device 182 with reverse polarity. The male and female connectors can be configured to provide intrinsically safe connection and disconnection to each other, and can be configured for hot swap insertion and removal. Convenient, plug-and-play installation and removal of the mechanical switch device 182 is possible, while ensuring the safety of the device during operation and in the removal and replacement of the modular mechanical switch device 182. A locking or latching feature can be provided on the terminals 188, 190, 192 or on the housing 186 to secure the mechanical switch device 182 and ensure a high-quality electrical connection. Loose terminal connections should be avoided as they can cause ignition problems in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations.

[0122] In contemplated alternative embodiments, lug terminals and the like may be built into the construction of the mechanical switch device 182, rather than being provided separately from the mechanical switch device 182. Depending on the installation, the mechanical switch device 182 including the built-in terminals may include additional housing features to enclose the built-in terminals. A secure wire or cable connection to the built-in terminals may be established via locking features, spring biasing features, and connectors to ensure a high quality electrical interconnection with the cable or wiring while ensuring an adequate degree of safety for explosive environments.

[0123] Mechanical switch device 182 Figure 6182 is shown connected to an external controller 202. The controller 202 can be programmed to provide automatic circuit protection according to a selected or predetermined time-current curve via the mechanical switching device 182. In the case where an internal controller is provided in the device 182, the controller 202 may be optional and need not be provided. The internal controller or the external controller can advantageously enable remote operation of the device 182.

[0124] Figure 7 An exemplary modular solid-state switch device 180 and terminal assembly are shown, which facilitates convenient interconnection to achieve the above combined modular mechanical switch device 282 ( Figure 6 ) as described in the modular circuit protection arrangement.

[0125] The modular solid-state switch device 180 includes a terminal post or pin 220 that protrudes from the rear side of the device housing 102 as shown. The separately provided terminals 220 and 224 include holes 226, 228 that receive the terminal post or pin 220 of the modular solid-state switch device 180. The post or pin 220 and the terminal holes 226, 228 define male and female connection features to complete the mechanical and electrical connection with and through the solid-state switch elements in the device 280 and the terminals 222, 224, which in turn connect to the bus 1 connection 198 and the bus 2 connection 200 (also in FIG. Figure 6 ), these connections define conductive structures in the switchboard for connecting to the line 132 and the load 136 in parallel with the mechanical switching device 182. In the contemplated embodiment, the terminals 220, 222 can be fixed to the bus structure, or can be fixed in place on another support structure, with wires or cables connected in place, so that the solid-state switching device 180 can be removed and replaced without disturbing the connection with the line-side circuit and the load-side circuit. The alternative terminal structures described above with respect to the above-mentioned mechanical switching device 182 are also possible.

[0126] Figure 7The male connection features and female connection features shown are exemplary only. Although the solid-state switch device 180 is shown as having a male connector post or pin, and the terminals 220, 222 are shown as having recessed holes 226, 228, in another embodiment, this can be effectively reversed to provide a male connector on the terminal and a female connector on the solid-state switch device 180. The size and shape of the post and hole can also vary to define the acceptance / rejection feature, thereby ensuring that only compatible devices can be used with compatible terminals, and also ensuring a one-way installation, which prevents inadvertent attempts to install the solid-state switch device 180 with reverse polarity. The male connector and the female connector can be configured to provide intrinsically safe connection and disconnection of each other, and can be configured for hot swap insertion and removal. Convenient, plug-and-play installation and removal of the solid-state switch device 180 is possible while ensuring safety. A locking or latching feature can be provided on the terminals 220, 222, 224 or on the housing 102 to secure the solid-state switch device 180 and ensure a high-quality electrical connection. Loose terminal connections should be avoided as they can cause ignition problems in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations.

[0127] In a contemplated embodiment, the male and female terminal connection features of the solid-state switch device 180 are different from the male and female terminal connection features of the mechanical switch device 182 to avoid human errors that may occur during installation. For example, the lateral and longitudinal spacing or positioning of the terminal posts or pins 220 on the rear side of the device 180 may be different from the lateral and longitudinal spacing or positioning of the terminal posts or pins of the device 182 to define an acceptance / rejection feature to allow each device 180, 182 to be installed in the proper location while rejecting any attempt to install them in an incorrect location. Thus, the mechanical switch device 182 cannot be inadvertently installed in the position of the solid-state switch device 180, and vice versa. Proper operation of the combination of devices 180, 182 depends on their proper connection to the mechanical switch device 182. Figure 6 and Figure 7 The corresponding terminals shown in Figure 4 and Figure 5 Arrangement shown.

[0128] The solid state switch device 180 is Figure 7 1 is shown connected to an external controller 202. The controller 202 can be programmed to provide automatic circuit protection operating on the input time-current curve via the solid-state switching device 180. In the case where an internal controller is provided in the solid-state switching device 180, the controller 202 may be optional and need not be provided. An internal controller or an external controller can advantageously enable remote operation of the device 180.

[0129] Compare Figure 7 and Figure 8, the controllers 202 are connected to each other and can therefore coordinate the operation of each device 180, 182 relative to each other, and ensure that compatible time-current characteristics are selected or implemented in each device to avoid possible misoperation or inadvertent failure of the desired circuit protection in use via mismatched time-current characteristics in each device.

[0130] For example, a solid-state device 180 rated at 100A (or operating at a 100A user-selected setting) in combination with a mechanical switch device 182 rated at 50A (or operating at a 50A user-selected setting) may compromise the intended load current sharing when desired, thereby affecting the intended circuit protection, and may render load current sharing entirely ineffective depending on the specific time-current characteristics of each device. Similarly, a solid-state device 180 rated at 50A (or operating at a 50A user-selected setting) in combination with a mechanical switch device 182 rated at 100A (or operating at a 100A user-selected setting) may not produce the desired amount of load current sharing when actually desired.

[0131] Likewise, to the extent that the device may include conflicting overload settings, erroneous operations unrelated to load current sharing may result. For example, if the mechanical switch device 182 is rated much lower than the solid-state switch device 180 (or if its selected settings are much lower than the solid-state switch), the mechanical switch device 182 may be overly sensitive to current conditions that are not actually a problem and thus will open and disconnect loads unnecessarily or in a manner that was not intended by the user or installer.

[0132] Thus, the controller 122 may compare and evaluate device ratings and / or selected settings to detect incompatible devices and device settings, reject incompatible settings, prompt the user for compatible device selection and / or generate notifications or alerts, while taking fail-safe measures, such as automatically adjusting input settings to the nearest compatible settings that ensure circuit protection and safe operation of the device. Alternatively, the controller 202 may accept or detect user setting inputs, evaluate them to identify any incompatibilities, and accordingly instruct the respective controller in each device 180 and 182 regarding the optimal and coordinated time-current characteristics of each device 180, 182 that ensure the desired safety without compromising circuit protection.

[0133] Figure 8 2 is a first partial front view of an exemplary power distribution board 250 including a set of terminals 222, 224 and multiple sets of terminals 190, 192. In the example shown, a set of terminals 222, 224 and three sets of terminals 190, 192 are mounted on the power distribution board 250 in the area of ​​the power distribution board shown. The set of terminals 222, 224 are positioned to receive the terminal posts or pins 220 ( Figure 7 Each set of terminals 190, 192 is positioned to receive a terminal post or pin 188 of a corresponding mechanical switch device 182 ( Figure 6 ). Fig. 9 2 shows the installation of the devices 180, 182 to the corresponding terminals 224, 224, 190, 192. The solid-state switch device 180 is shared by each of the mechanical switch devices 182 through the bus structure of the distribution board 250 according to the modular circuit arrangement concept described above to connect the solid-state switch devices 180 in parallel to the mechanical switch devices 182, thereby achieving the load current sharing.

[0134] The controller 202 may be located remotely from the switchboard 250, or may be mounted on the switchboard 250. Using the controller 202, the trip settings of the mechanical switch devices 182 and / or the solid-state switch devices 180 in the panel may be varied for a particular installation and for a particular load. Likewise, the bus structure of the panel 250 may be configured via software or hardware implementation to interconnect the mechanical switch devices 182 and the solid-state switch devices 180 in a desired circuit arrangement, including, but not limited to, those described above. In a contemplated embodiment, the switchboard 400 may be a single integrated circuit device having multiple programmable channels to accommodate a desired combination of single-pole circuits, two-pole circuits, and three-pole circuits. Thus, and in Fig. 9 In the example shown, the three mechanical switch devices 182 can be configured to power a three-phase electrical load using all three mechanical switch devices 182, a two-phase electrical load including only two mechanical switch devices 182, or three single-phase loads connected through respective ones of the three mechanical switch devices 182. Using the modular devices, modular bus configurability, and programmable controls and circuit arrangements described above, considerable variation of the power distribution board 250 is possible for a particular end use without having to provide different versions of the power distribution board and devices or customizing the power distribution board and devices to satisfy a wide range of applications in the art.

[0135] In contemplated embodiments, the switchboard 250 may be safely operated without the need for a conventional explosion proof enclosure, thereby reducing costs and simplifying maintenance issues for equipment located on the switchboard.

[0136] Fig.10 1 is a perspective view of a compliant hazardous environment arc-free circuit protection device 300 according to another exemplary embodiment of the present invention. The circuit protection device 300 includes the housing 102 described above with respect to the device 100, but omits the digital display 116 ( Figure 1 ).like Fig.10As 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.

[0137] Similar to device 100, device 300 can interconnect a line-side circuit or power circuit with an electrical load that operates 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 a predetermined overcurrent condition, 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 prescribed time-current characteristic or time-current curve 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.

[0138] 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.

[0139] 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 discussed 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 locations in terms of arc discharge.

[0140] 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.

[0141] 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, 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 expected, 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 contacts of each mechanical circuit breaker 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 switch.

[0142] In addition, the device 300 also includes a motor starting and motor overload component 314 inside the housing 102. The sensors in the device and the processor 150 in the device 300 implement sensor feedback and functions of conventional and separately provided motor starter components to control motor operation in a known manner. Motor control operations include control of motor starting events (including but not limited to so-called soft start events), motor stop and reversal events, motor overload events, and power loss events while the motor is operating. Such motor control components and functions are intended to protect the motor and provide safe operation of the motor under specific operating conditions, which may or may not be related to overcurrent or electrical fault conditions in the power system itself. The sensors and intelligence provided in the device 300 can take into account and allow for motor surge currents and other electrical conditions within predetermined limits that otherwise may be considered undesirable from a simpler circuit protection perspective that does not consider the unique needs of motor control.

[0143] Although a motor starter and overload component 314 are described, other dual-purpose or dual-function integrations in device 300 are also possible, which will also further reduce the cost of installing and servicing the power system by reducing the number of devices that need to be acquired, installed and repaired in the power system and the conventional explosion-proof enclosures associated with the required devices.

[0144] Thus, a hybrid device 300, which includes adequate housing structure, mechanical circuit breakers and solid state switches to enhance circuit protection capabilities and safe operation in hazardous environments, and motor starter components, is economically provided in a single package that does not require an explosion proof enclosure. The device 300 can be economically provided to replace the conventional arrangement of separately provided circuit breakers, contactors, and motor starter components connected in series with each other, and is typically provided with a conventional explosion proof enclosure to achieve safety in a NEC Section 2 or Section 1 location or an IEC Zone 1 or Zone 2 location. The device 300 can be provided in a modular form including the above-described terminal structure and components, and can be arranged and controlled in a configurable switchboard installation to power a desired number of motors.

[0145] The device 300 may also be connected to an electrical ground 146 to dissipate any charging of the housing surface as described above, thereby eliminating a possible ignition source via electrostatic discharge as described above. In contemplated embodiments, the housing 102 of the device 300 may be made of a metal or non-metal material. In some cases involving certain metal or non-metal materials, the housing material, filler material, and packaging material must be strategically selected to address static issues. A combination of conductive and non-conductive materials may be utilized within the device 300 and outside the device 300 to appropriately provide a path to an electrical ground.

[0146] Although an exemplary architecture of apparatus 300 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.

[0147] 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.

[0148] like Fig.13 As shown above, in addition to Fig. 9In addition to the thermal management features described above for device 100, device 300 includes additional features to ensure that any arcing that occurs during operation of the mechanical switch contacts is isolated from the surrounding environment or otherwise reduced to a level insufficient to cause ignition in a hazardous location. Fig.13 The 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.

[0149] 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 locations 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.

[0150] 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 are 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 disconnection function when manually actuated to facilitate maintenance of the power system or automatically actuated to protect the electrical load connected by the device 100.

[0151] Either device 100 or 300 can be safely used in a Zone 1 or Zone 2 of the IEC or a Division 1 or 2 of the NEC hazardous location without the need for a conventional separately provided explosion proof enclosure. The above-mentioned built-in anti-ignition feature eliminates ignition sources or reduces 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 a separate explosion proof enclosure. Therefore, the devices 100 and 300 prevent possible explosions that would normally exist in an explosion proof enclosure to safely control. 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.

[0152] Fig.14 An exemplary panelboard 400 including compliant hazardous location arc-free circuit protection devices is shown, which include 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 may include the devices 100, 180, 182 and / or 300 described above, and the devices 402, 404 may be represented by different ratings, which provide different degrees of circuit protection for the various different loads served by the panel and its various branches. The panelboard 400 typically includes its own enclosure, but because of the ignition-proof devices 402, 404 used on the panelboard, the enclosure of the panelboard 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 panelboard enclosure without the need for a conventional explosion-proof enclosure in the panelboard enclosure. The switchboard enclosure protects the devices 402, 404 from environmental conditions, but the switchboard enclosure does not need to be explosion proof because the devices 402, 404 are ignition proof. Considering that known switchboards can accommodate up to 84 devices, eliminating the separately provided individual explosion proof enclosures and the shared explosion proof enclosure significantly reduces the operating cost of the devices 402, 404 in hazardous locations. For large power systems including multiple switchboards located at different locations, the cost is even further multiplied. In a contemplated embodiment, 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.

[0153] 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.

[0154] While a switchboard and switchboard enclosure are described above with respect to 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 likewise located in non-explosion proof enclosures.

[0155] Figures 15 to 17 The above-described devices 100, 180, 182, 300, 402 and 404 are shown to have a dual function capability of providing different and / or alternative types of circuit protection in a single device package, which may provide cost reductions and space savings in hazardous locations in addition to eliminating explosion proof enclosures that are otherwise conventionally provided.

[0156] Fig.15 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device (such as one of devices 100, 180, 182, 300, 402 and 404 described above) is shown, which is configured to simulate the time-current curve of an overcurrent protection fuse to achieve desired goals in certain installations.

[0157] like Fig.15 As shown in the example of , sometimes different types of circuit protectors need to be combined to protect certain electrical loads, and the time-current response characteristics of different circuit protectors need to be coordinated to achieve the best circuit protection. For example, the three time-current curves in Fig.15 450, 460, 470, which may be implemented in different circuit protectors to provide enhanced circuit protection features that no circuit protector itself can provide separately.

[0158] Time-current curve 450 represents a time-current response curve of an electronic trip curve of a circuit breaker that may be programmed into one of devices 100, 180, 182, 300, 402, and 404, or may be implemented in a separately provided and otherwise conventional circuit breaker having an electronic trip unit to interrupt current flowing through the circuit breaker under predetermined time-current conditions represented by time-current curve 450. Time-current curve 450 is capable of providing predetermined circuit interruption under so-called "long time," "short time," and "instantaneous" overcurrent conditions, in accordance with the definition of "circuit breaker" mentioned above, as opposed to more general purpose switchgear having a more limited range of overcurrent circuit protection capabilities than circuit breakers.

[0159] Time-current curve 460 represents the time-current response curve of the thermal-magnetic circuit breaker, which also provides predetermined circuit interruption under so-called "long time", "short time" and "instantaneous" overcurrent conditions. Fig.15 In the example shown, the time-current curve 460 is located outside and to the right of the time-current curve 450. Therefore, when the device having the time-current curve 460 is connected in series with the device having the time-current curve 450, the time-current characteristics of the devices will not conflict with each other, and one of the devices will not trip erroneously. In the example shown, the device having the time-current curve 460 will never open the circuit before the device having the time-current curve 450.

[0160] By virtue of the programmable configurability of the time-current response of devices 100, 180, 182, 300, 402, and 404, each of these devices can be selectively configured and used to implement the time-current curve 450 or 460 and operate safely in a hazardous location without the need for a separately provided explosion-proof enclosure. That is, two such devices 100, 180, 182, 300, 402, and 404 can be connected in series with each other and operate according to different time-current curves to achieve an effect similar to the conventional coordination of different circuit protectors in an anti-ignition manner for safe use in hazardous locations. Settings and inputs for a particular time-current curve (which may be similar to or different from the exemplary time-current curve 450 or 460) can be selected locally or remotely to operate devices 100, 180, 182, 300, 402, and 404 in a desired manner.

[0161] Likewise, the devices 100, 180, 182, 300, 402, and 404 can be connected to conventional circuit breaker devices, wherein each of these devices implements one of the time-current curves 450 or 460, respectively, to achieve coordination in the combination of the circuit breaker devices shown. Such conventional circuit breaker devices may be enclosed in a separately provided explosion-proof enclosure in a hazardous location, but the devices 100, 180, 182, 300, 402, and 404 do not need to be. Therefore, the devices 100, 180, 182, 300, 402, and 404 can be installed in an existing power system in a retrofit manner in combination with conventional non-compliant devices for use in hazardous locations, and thus require a separate explosion-proof enclosure.

[0162] Fig.15 The time-current curve 470 shown represents the time-current response curve of an overcurrent protection fuse that can be used in conjunction with the device having the time-current curve 450 and / or 460. Unlike the circuit breaker time-current curves 450, 460 (which are inherently discontinuous as shown in the figure in order to provide different so-called "long time", "short time" and "instantaneous" characteristic circuit breaker protection), the time-current curve 470 of the fuse is continuous and is also located outside and to the right of the time-current curve 460. Therefore, when a device having the time-current curve 470 is connected in series with a device having the time-current curve 460, the time-current characteristics of the devices will not conflict, and one of the devices will not be accidentally disconnected. In the example shown, the device having the time-current curve 470 will never disconnect the circuit before the device having the time-current curve 460.

[0163] By virtue of the programmable configurability of the time-current response of devices 100, 180, 182, 300, 402, and 404, these devices can each be selectively configured and used to implement the time-current curve 470 or 460 and operate safely in a hazardous location without the need for a separately provided explosion-proof enclosure. That is, each of the devices 100, 180, 182, 300, 402, and 404 can be configured to exhibit the circuit protection characteristics of a circuit breaker (e.g., via exemplary curves 450 and 460) or to exhibit the circuit protection characteristics of a fuse (e.g., via exemplary curve 470). Therefore, two such devices 100, 180, 182, 300, 402, and 404 can be connected in series with each device implementing the time-current curve 470 or 460, respectively, to achieve coordination in the combination of circuit breaker devices shown. Settings and inputs for a particular time-current curve (which may be similar to or different than exemplary time-current curves 470 , 460 , or 450 ) may be selected locally or remotely to operate devices 100 , 180 , 182 , 300 , 402 , and 404 in a desired manner.

[0164] Additionally, the time-current curve 470 may be implemented in one of the devices 100, 180, 182, 300, 402, and 404, and the time-current curve 460 may be implemented in a conventional circuit breaker device that would need to be enclosed in a separately provided explosion-proof enclosure for use in hazardous locations, or may be implemented in a conventional overcurrent protection fuse that may require a separately provided explosion-proof enclosure.

[0165] When the device 100, 180, 182, 300, 402, or 404 is implemented to implement the time-current curve 470, the device 100, 180, 182, 300, 402, or 404 simulates the desired circuit protection performance of an overcurrent protection fuse by tripping open under substantially the same time-current conditions as the fuse would otherwise, while still providing a conveniently resettable device to restore full operation of the affected circuit. However, it should be recognized that in certain installations and certain circuit conditions, due to fundamental differences in the way fuses and circuit breakers interrupt current, actual overcurrent protection fuses will inherently respond to short circuit conditions faster than certain types of circuit breakers, and the faster response time of fuses is the primary reason why it is desirable to coordinate the time-current curves 470 and 460 or 450. Nevertheless, in some cases, the simulation of a fuse by device 100, 180, 182, 300, 402 or 404 can provide most of the benefits of fusible circuit protection without the need to locate a replacement fuse to restore the protected circuit after a short circuit event, as would be required if an actual overcurrent protection fuse were provided for a similar purpose.

[0166] Fig.16 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device according to another exemplary embodiment of the present invention is shown, which is configured to simulate the time-current curve circuit protection of a motor circuit protector. Fig.16 As shown, the device 100, 180, 182, 300, 402, or 404 is programmatically configured to exhibit a time-current curve 500 that is located outside and just to the right of the peak surge current curve shown at 502 for the motor start event. Therefore, and by virtue of the time-current curve 500, the device 100, 180, 182, 300, 402, or 404 will not trip open in response to the motor start surge current. Nuisance tripping of the device 100, 180, 182, 300, 402, or 404 is thus avoided, while otherwise providing circuit protection for non-motor start overcurrent conditions.

[0167] The configurable programmability of the device 100, 180, 182, 300, 402, or 404 can accommodate a variety of different inrush currents for different motor applications with a single device that can be universally used for different types of motors. Fig.16 502 is shown with a minimum setting that almost coincides with the peak surge current, but the configurable programmability of the device can also easily allow the time-current curve 502 to be shifted further to the right and thus more accurately than Fig.16 The settings and inputs for a particular time-current profile, which may be selected relative to a particular surge current profile, may be selected locally or remotely to operate the devices 100, 180, 182, 300, 402, and 404 in a desired manner.

[0168] Fig.17 An exemplary time-current curve of a configurable compliant hazardous location arc-free circuit protection device according to another exemplary embodiment of the present invention is shown, which is configured to simulate a thermal overload time-current curve of a motor circuit protector. Fig.17 In the example of FIG. 5 , three time-current curves are shown as 520 , 522 , 524 , which in combination provide enhanced circuit protection characteristics that no single circuit protector by itself can provide separately to provide circuit protection for a motor.

[0169] The time-current curve 520 is a time-current curve of a circuit breaker, which may be programmatically implemented in one of the configurable devices 100 , 180 , 182 , 300 , 402 , or 404 described above.

[0170] Fig.17 To the left of the time-current curve 520 in FIG. 5 is a time-current curve 522 that is typically implemented by a thermal overload relay provided in conjunction with a series connected circuit breaker arrangement having the time-current curve 520. Thus, the overload curve 522 will respond first to an overload condition before the time-current curve 520.

[0171] Fig.17 To the right of the time-current curve 520 in FIG. 5 is a motor damage curve 524, which represents a threshold time-current condition that, if exceeded, will result in damage to the motor wiring or other components in the motor itself. The time-current curve 520 of the circuit breaker (which can be implemented in one of the configurable devices 100, 180, 182, 300, 402, or 404) protects the motor by ensuring that the current flowing to the motor always remains below the motor damage curve 524.

[0172] The flexibility of the configurable devices 100, 180, 182, 300, 402, or 404 allows them to incorporate circuit protection with an overload curve 522 so that thermal relays can be eliminated while providing circuit protection comparable to conventional series-connected relays and circuit breakers.

[0173] Solid-state or hybrid devices (such as those described above) can be constructed using a variety of different solid-state switching elements, different arrangements of solid-state switching elements, and also implemented in a variety of different power electronic device topologies. Various different implementations are envisioned, involving different degrees of on-state losses, tendency to arc discharge in operation, conduction losses, component counts, relative complexity, the ability to meet specific response time characteristics, simplicity or complexity of operating algorithms, and the ability to integrate motor soft start or other features when needed. Solid-state switching elements can be connected in series or in parallel using a modular arrangement to achieve the required rated voltage scaling or the required rated current scaling. In terms of the desired implementation of bypass contacts, packaging materials and thermal management features provided for the bypass contacts may be desirable.

[0174] 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.

[0175] The above principles can be easily applied to realize circuit protection devices that are not circuit breaker devices, but are still ignition proof for use in IEC Zone 1 or NEC Division 2 hazardous locations without the need for a separate explosion proof enclosure. For example, the above discussion discusses fusible switch disconnect devices that include a mechanical switch combined with a fuse. Applying the above arc-free operation, thermal management features and modular concepts, solid-state fusible switch disconnect devices or hybrid fusible switch disconnect devices can be easily constructed to have similar benefits, but provide different degrees of circuit protection.

[0176] Likewise, the arc-free operation, safety terminal assembly, and thermal management devices described above can be readily applied to implement switchgear that do not provide circuit protection per se, but are still ignition proof for use in IEC Zone 1 or Zone 2 locations and NEC Division 1 and 2 hazardous locations without the need for a separate explosion proof enclosure. For example, mechanical relay switches and contactors are known that provide a circuit breaker function but do not have the ability to protect against overcurrent conditions. Applying the arc-free operation, thermal management features, and modular concepts described above, solid-state relay devices or hybrid relay devices and solid-state contactor devices or hybrid contactor devices can be readily constructed to have similar benefits as those described above.

[0177] 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 multi-phase power systems and multi-phase power systems), while generally providing anti-ignition functions for use in IEC Zone 1 or Zone 2 or NEC Section 1 or Section 2 hazardous locations.

[0178] 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 the programming of a controller or other processor-based device. It is considered that such programming or implementation of the algorithm concept is within the scope of those skilled in the art and will not be further described.

[0179] It is now believed that the benefits and advantages of the inventive concepts have been fully demonstrated in accordance with the disclosed exemplary embodiments.

[0180] An embodiment of a configurable modular hazardous location compliant circuit protection system for hazardous environments has been disclosed. The system includes: at least one modular switchgear having a housing; line-side terminals and load-side terminals coupled to the housing; and a solid-state switch element operable in an arc-free manner to connect the load-side terminals to the line-side terminals and disconnect the load-side terminals from the line-side terminals. The system also includes a controller configured to operate the solid-state switch element to share a current load with at least one mechanical switchgear, thereby limiting arc energy to a level below that causing ignition issues in a hazardous location, whereby at least one modular switchgear and at least one mechanical switchgear are each compliant for use in an explosive environment without requiring a separately provided explosion-proof enclosure.

[0181] Optionally, the system may be combined with at least one mechanical switching device, and the at least one mechanical switching device may be provided in a modular enclosure separate from the at least one modular switching device. The at least one modular switching device may be a single-pole device, and the at least one mechanical switching device may also be a single-pole device. The number of mechanical switching devices may be greater than the number of modular switching devices in the system.

[0182] As a further option, at least one modular switchgear may include line terminals and load terminals configured for plug-in connection to separately provided line terminals and load terminals. The terminals of at least one modular switchgear may be posts or terminals for plug-in connection with separately provided terminals. The line-side terminals and load-side terminals and the separately provided line terminals and load-side terminals may be configured in combination to reject connection of non-compatible devices. The line-side terminals and load-side terminals and the separately provided line-side terminals and load-side terminals are configured in combination to allow at least one modular switchgear to be connected only with the proper polarity. The separately provided line-side terminals and load-side terminals may be provided on the switchboard assembly.

[0183] The controller may optionally be provided separately from the at least one modular switch device. The at least one modular switch device and the at least one mechanical switch device may each be configured as a circuit breaker. The at least one modular switch device may be configured to simulate the circuit protection of an overcurrent protection fuse, may be configured to coordinate its time-current curve with a separate circuit protector, and / or may be configured to coordinate its time-current curve with the inrush current of the electrical load. The at least one modular switch device may also be configured to simulate the circuit protection curve of a thermal motor protector and / or coordinate with a motor damage curve.

[0184] The solid state switch element may be encapsulated. The at least one mechanical switch device may be sealed to prevent ignitable elements from entering the hazardous location. The at least one mechanical switch device may be vacuum sealed or may be filled with a dielectric material, dielectric fluid, potting material or sand to contain, absorb or dissipate heat and energy during operation of the solid state switch element, thereby ensuring that the surface temperature of the mechanical switch device will remain below a selected target temperature of the hazardous environment.

[0185] 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. A configurable, modular hazardous location compliant circuit protection system for use in hazardous environments, the system comprising: At least one modular switchgear, the at least one modular switchgear comprising: shell; a line-side terminal and a load-side terminal coupled to the housing; a solid-state switching element operable in an arc-free manner to connect and disconnect the load-side terminals from the line-side terminals; and a controller configured to operate the solid-state switching element to share a current load with at least one mechanical switching device to limit arc energy to a level below that causing ignition problems in the hazardous location; Whereby the solid-state switching element is connected in parallel to the at least one mechanical switching device, the at least one modular switching device and the at least one mechanical switching device are each compliant for use in an explosive environment without the need for a separately provided explosion-proof enclosure.

2. The system of claim 1, in combination with the at least one mechanical switching device, the at least one mechanical switching device being provided in a modular enclosure separate from the at least one modular switching device.

3. A system according to claim 2, wherein at least one of the modular switching devices is a single-pole device.

4. The system of claim 3, wherein the at least one mechanical switching device is a single-pole device.

5. A system according to claim 4, wherein the number of mechanical switching devices is greater than the number of modular switching devices.

6. The system of claim 1, wherein the at least one modular switch device comprises a line terminal and a load terminal, the line terminal and the load terminal being configured for plug-in connection to separately provided line terminals and load terminals.

7. The system according to claim 6, wherein the line-side terminals and the load-side terminals of the at least one modular switch device are posts or terminals for plug-in connection with the separately provided terminals.

8. The system of claim 6, wherein the line-side terminal and the load-side terminal and the separately provided line terminal and load terminal are configured in combination to reject connection of a non-compliant device.

9. The system according to claim 6, wherein the line-side terminals and the load-side terminals and the separately provided line terminals and load terminals are configured in combination to allow the at least one modular switching device to be connected only with appropriate polarity.

10. The system of claim 6, wherein the separately provided line terminals and load terminals are provided on a distribution board assembly.

11. The system of claim 1, wherein the controller is provided separately from the at least one modular switchgear.

12. The system of claim 1, wherein the at least one modular switch device and the at least one mechanical switch device are each configured as a circuit breaker.

13. The system of claim 12, wherein the at least one modular switch device is configurable to simulate circuit protection of an overcurrent protection fuse.

14. The system of claim 12, wherein the at least one modular switchgear is configurable to coordinate its time-current curve with a separate circuit protector.

15. The system of claim 12, wherein the at least one modular switch device is configurable to coordinate its time-current curve with an inrush current of an electrical load.

16. The system of claim 12, wherein the at least one modular switchgear is configurable to emulate a circuit protection curve of a thermal motor protector.

17. The system of claim 12, wherein the at least one modular switch device is configurable to coordinate with a motor damage curve.

18. The system of claim 1, wherein the at least one mechanical switching device is sealed to prevent ignitable elements from entering the hazardous location.

19. The system of claim 18, wherein the at least one mechanical switching device is vacuum sealed.

20. The system of claim 18, wherein the at least one mechanical switching device is filled with a dielectric material, a dielectric fluid, a potting material, or sand to contain, absorb, or dissipate heat and energy during operation of the solid-state switching element, thereby ensuring that a surface temperature of the mechanical switching device will remain below a selected target temperature of the hazardous environment.

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