Circuit protection device, system and method with safety lockout / tagout component

Abstract

The present invention discloses a hazardous location compliant solid-state circuit protection device, which includes a safety lockout component that ensures circuit disconnection as a guarantee for responsible personnel to complete power system maintenance tasks. The safety lockout component may include a mechanical lockout component engaged with a physical lock element, an electrical lockout component implemented by a control of a solid-state circuit breaker device, and a combination thereof. The following visual device feedback and confirmation can be provided to the responsible personnel: the lockout component has been successfully activated, and the lockout component has been successfully deactivated to reconnect and restore the operation of the load-side circuit.

Description

Background Art

[0001] The field of the invention relates generally to circuit protection devices, and more particularly to hazardous environment compliant circuit protection devices that include an enhanced safety lockout feature for accomplishing power system maintenance tasks.

[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. In the presence of such devices, output power can be selectively switched from a power supply by such devices, either manually or automatically, to facilitate maintenance of the power system and to resolve electrical fault conditions. Circuit breaker devices and fusible disconnect switch devices are two well-known types of devices that each provide different capabilities for responding to overcurrent and electrical fault conditions and 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 the market demand. 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 yes Figures 1 to 3 A front view of a circuit protection device is shown, illustrating an exemplary safety lockout / tagout component of the circuit protection device.

[0009] Figure 5 yes Figure 4An end view of a circuit protection device is shown in an open position, showing the safety lockout / tagout component engaged.

[0010] Figure 6 yes Figure 4 An end view of a circuit protection device is shown in a connected state with an exemplary safety lockout / tagout component disengaged.

[0011] Figure 7 yes Figures 4 to 6 An exemplary algorithm flow chart of the safety lockout activation and deactivation procedure for the illustrated device.

[0012] Figure 8 is a perspective view of a compliant hazardous location arc-free circuit protection device according to a second exemplary embodiment of the present invention.

[0013] Fig. 9 is in an exemplary hybrid configuration Figure 8 A simplified schematic diagram of a circuit protection device is shown.

[0014] Fig.10 yes Figure 8 and Fig. 9 A block diagram of a circuit protection device is shown.

[0015] Fig.11 It shows schematically Figures 8 to 10 Thermal management features of a circuit protection device are shown.

[0016] Fig.12 An exemplary switchboard including compliant explosive location circuit protection devices is shown. DETAILED DESCRIPTION

[0017] In order to best understand the inventive concepts described herein, a discussion of the prior art as it relates to problems arising from hazardous locations is set forth below, followed by exemplary embodiments of devices, systems, and methods that address such problems and satisfy a long-standing but unmet need in the art.

[0018] I. Prior Art

[0019] Electrical systems sometimes operate in hazardous environments where there is a risk of explosion due to ignition of dust, fibers or flying dust from the surrounding gases or vapors. 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 substances 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, which in some cases may generate ignition sources during normal operation and electrical faults with the help of conventional circuit protection devices. Therefore, based on the assessed probability of explosion or fire risk, many standards have been promulgated for the use of electrical products in explosive environments to improve safety in hazardous locations.

[0020] 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 the 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.

[0021] 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.

[0022] 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, a Zone 0 location is a location where flammable gases or vapors are present in ignitable concentrations continuously or for long periods of time. A Zone 1 location is a location where flammable gases or vapors in ignitable concentrations may 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 is a location adjacent to a Zone 0 location from which ignitable vapors in ignitable concentrations may be transferred.

[0023] 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 placed in NEC Section 1 or 2 locations and / or IEC Zone 1 or 2 locations to contain electrical devices that would otherwise 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-proof enclosure must operate at a safe temperature relative to the surrounding air.

[0024] 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.

[0025] 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

[0027] breaker

[0028] 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

[0030] Switch (mechanical)

[0031] 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]

[0032] Note that the switch can turn on but not turn off the short-circuit current. 2.2.1

[0034] Switchgear

[0035] Devices designed to connect or disconnect current in one or more circuits [441-14-01]

[0036] Note that a switching device may perform one or both of these operations.

[0037] As can be seen from the above definitions, the difference between the circuit breaker defined in IEC 2.2.11 and the mechanical switch defined in IEC 2.2.9 lies in their different abilities to mechanically respond to abnormal circuit conditions. Specifically, the circuit breaker defined in IEC 2.2.11 can mechanically disconnect a short circuit condition, while the mechanical switch defined in IEC 2.2.9 cannot disconnect a short circuit condition. Therefore, electrical fuses are sometimes used in conjunction with the mechanical switch of IEC 2.2.9 to implement a fusible disconnect switch that can respond to a short circuit condition by the operation of the fuse (i.e., the opening of the fuse) rather than the operation of the mechanical switch contacts.

[0038] In either device 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:

[0039] Fuse: An overcurrent protection device with a fusible component that is heated and melted by the passage of overcurrent, thereby breaking the circuit.

[0040] 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.

[0041] The NEC also requires that circuits be provided with disconnecting devices, defined as devices or groups of devices, or other devices that disconnect circuit conductors from the power supply 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.

[0042] 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.

[0043] In contrast to the circuit protection devices described above, the "switching device" of IEC 2.2.1 as defined above is concerned only with making and breaking current, and not with making or breaking overcurrent conditions (i.e., overload conditions or short circuit conditions). The "switching device" of IEC 2.2.1 therefore provides a circuit breaking function, but not a circuit protection function. IEC 2.2.1 also does not require mechanical switching devices at all, but if a switching device that is not a circuit breaker device actually includes mechanical switch contacts, it may still pose an ignition risk when located in a hazardous environment.

[0044] 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 mechanically moves 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 can 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, as well as an additional enclosure typically used with a switchboard or motor control center, etc., such housings and enclosures are generally not sufficient to isolate the arc from ignitable gas-borne elements. To this end, known devices including mechanical switch contacts are typically located in separate explosion proof enclosures that are then contained in an environmental enclosure, or in a switch system (i.e., a switchboard) that may in turn be mounted in a single large explosion proof enclosure, without the need for a separate explosion proof enclosure for switches located within Section 1 locations of the NEC to provide the necessary protection.

[0045] 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 temperature under lower current overload conditions and normal conditions are also considerable and high, thus creating 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 greater the current being disconnected, the greater the possibility and severity of arc discharge. For example, from the perspective of arc discharge, the interruption of a 65kA IC is much more significant than the interruption of a 10kA IC, and is therefore more dangerous.

[0046] Available explosion-proof, flameproof or ignition-proof enclosures effectively enable mechanical switching devices in NEC Section 1 or 2 locations or IEC Zone 1 or 2 locations to operate safely, but typically come with added 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 breaking device within the explosion-proof enclosure typically requires the time-consuming removal of multiple fasteners, and after any maintenance procedures are completed, all fasteners must be properly replaced to ensure the required safety of the explosion-proof enclosure. During the maintenance procedure, the area where the circuit breaking device is located is typically shut down (i.e., disconnected), while the related load-side processes are stopped to ensure safety during the maintenance procedure. From the perspective of the industrial facility, such downtime is costly, and it is important to limit or shorten the downtime. Therefore, in some cases, it would be desirable if the explosion-proof enclosure could be eliminated in NEC Section 1 locations while still providing a safe circuit breaking function in a hazardous environment. To this end, circuit protection devices designed to reduce the risk of ignition are needed, but such devices generally do not exist today.

[0047] 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.

[0048] 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.

[0049] 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 at the terminal location, if not arcing. 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 supplementally 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.

[0050] So-called hybrid disconnecting devices are also known, which include a semiconductor switch or a combination of a semiconductor device and a mechanical switch contact. Such hybrid devices can likewise be implemented in a circuit breaker device or used in combination with a fuse to resolve electrical fault conditions in an automatic manner. Hybrid disconnecting devices create a mixture of the above-mentioned problems from the point of view of possible ignition sources in hazardous locations and do not ensure adequate safety without the supplementary use of explosion-proof enclosures in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations.

[0051] II. Inventive No-Arc Devices, Systems, and Methods for Hazardous Location Compliance.

[0052] 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 in NEC Division 1 or 2 locations or IEC Zone 1 or 2 locations without necessarily requiring a separately provided explosion proof, flame proof, or ignition proof enclosure. Thus, by eliminating a separately provided explosion proof, flame proof, or ignition proof enclosure, the exemplary circuit protection devices described herein may be implemented in an electric power system, not only reducing costs, but also conserving valuable space in switchboards, 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 an electric power system. Some aspects of the method will be discussed explicitly and others will become apparent from the following description.

[0053] 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 process of switching a device to connect or disconnect a load-side circuit through a solid-state switching device, combined with enhanced features for addressing possible ignition sources at the connection terminals, and / or including thermal management features for addressing possible overheating of conductive elements built into 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 Division 1 or Division 2 locations of the NEC or Zone 1 or Zone 2 locations of the IEC, thereby allowing conventional explosion-proof, flameproof, or ignition-proof enclosures to be eliminated for certain applications.

[0054] In a second aspect, an exemplary hazardous location compliant solid-state circuit breaker device may be provided with a safety lockout / tagout mode that ensures disconnection through the solid-state circuit breaker device as a safeguard for responsible personnel to complete maintenance tasks on the power system. In different embodiments, the safety lockout / tagout mode may be characterized by a mechanical lockout engaged with a physical lock element, an electrical lockout achieved through the electronic controls of the solid-state circuit breaker device, and a combination thereof. Personnel may be provided with visual device feedback and confirmation that the lockout condition has been successfully activated to disconnect the load-side circuit so that the worker can safely continue to perform applicable maintenance or servicing procedures on the load side of the device in a safe manner. Personnel may also be provided with visual feedback and confirmation that the lockout condition has been successfully deactivated to complete the tagout procedure and reconnect and resume operation of the load-side circuit.

[0055] 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 the hybrid circuit protection device may also incorporate enhanced features to isolate the arc between the mechanical switch contacts from the surrounding environment to prevent ignition, and 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.

[0056] In a fourth aspect, an exemplary hazardous location compliant hybrid circuit protection device may be provided with a safety lockout / tagout mode that ensures disconnection through the hybrid circuit protection device as a safeguard for responsible personnel to complete maintenance tasks on the power system. In different embodiments, the safety lockout mode may be characterized by a mechanical lockout component engaged with a physical lock element, an electrical lockout component implemented through a control of a solid-state circuit breaker device, and a combination thereof. Personnel may be provided with visual device feedback and confirmation that the lockout condition has been successfully activated to disconnect the load-side circuit so that the worker can safely continue to perform applicable maintenance or servicing procedures on the load side of the device in a safe manner. Personnel may also be provided with visual feedback and confirmation that the lockout condition has been successfully deactivated to complete the tagout procedure and reconnect and restore operation of the load-side circuit.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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 the vibration and impact forces that may occur in an explosive environment, as well as provide chemical resistance to withstand exposure to chemicals in the 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.

[0061] 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. 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, then the sample casing complies with UL 1203.

[0062] By virtue of its manufacturing materials, the housing 102 should also exhibit chemical compatibility with specific chemicals present in a given NEC Section 1 or Section 2 location or IEC Zone 1 or Zone 2 location. Chemical compatibility refers to the stability of the housing when exposed to substances in the hazardous location environment. If the housing 102 reacts chemically with substances in the environment, it is considered to be incompatible. Therefore, in view of the number of different corrosive or caustic chemicals and substances used in various industrial facilities, it is recommended to conduct 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, and chemical compatibility testing can therefore be considered optional.

[0063] 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.

[0064] 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.

[0065] 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, dielectric fluid, 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 a desired temperature grade or temperature rating.

[0066] 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.

[0067] 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 located 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 it 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).

[0068] 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.

[0069] 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 supply on one of the sides 108, 110, respectively, and to a three-phase load-side device on the other side. The power supply and the load can each be operated with alternating current (AC) or direct current (DC). 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, 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.

[0070] 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 as prompted. 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 can simulate a traditional toggle switch to change the state to "on" or "off", without the displacement of the mechanical switch contacts when doing so, 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.

[0071] 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 user input related to the prompt or information presented on the display 116. However, it should be recognized that in certain embodiments, the display or display array 116 may be considered optional and need not be included at all. In other embodiments, additional input / output elements may be provided, whether in the form of a display or other interface for local and remote interaction between the user and the device.

[0072] 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.

[0073] 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 series-connected insulated gate bipolar transistors (IGBTs) 142a, 142b, 142c, 142d, respectively, connected in reverse to each other, wherein each pair of IGBTs 142a, 142b, 142c and 142d includes a varistor element 144 connected in parallel to the IGBTs. The reverse-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.

[0074] The IGBTs 142a, 142b, 142c, 142d are a form of semiconductor switch that is operable to allow current to flow from the line side circuit 132 to the load side circuit 136 between the corresponding input terminals and output terminals (130a and 134a, 130b and 134b, and 130c and 134c), or to prevent current from flowing through the device 100, so 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. Equivalent types of semiconductor switching elements 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 thyristors), etc. The number of semiconductor switching elements may be changed to be greater or less than Figure 2 Quantity shown.

[0075] 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 emergence 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 144 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 the motor start-up is completed. However, in other applications, the varistor may be considered optional and may be omitted.

[0076] As another thermal management feature, the solid-state switching devices (e.g., IGBTs) 140a, 140b, and 140c in each arrangement may be encapsulated with a material strategically selected or otherwise formulated to improve 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.

[0077] 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.

[0078] In view of the hazardous environments in which the device 100 is to be used, reliable termination of the line-side and load-side cables to the input and output terminals is important, as loose connections can 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 may be accessed 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 loosen over time. However, depending on the specific end use of the device 100 and its operating conditions, 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.

[0079] In NEC Section 1 locations, the input and output terminals may be further enclosed in additional housing portions to provide additional safety assurance. Such housing portions may be provided separately from the housing 102, or may be integrally formed as an extension of the housing 102 to isolate the input and output terminals from the explosive environment. In a contemplated embodiment, a removable cover element may be provided to access the input and output terminals and complete the electrical connection with the input and output terminals within the housing of the housing portion. Line-side and load-side cable connections may be further established, for example, by providing ingress protection, sealing, and grounding through armored cables and cable glands to safely pass line-side cables or load-side cables through the housing of each housing portion. When used with armored cables, a grounding to earth path may be established via a cable gland. However, in all embodiments, armored cables are not required and may not be used. Cable glands may also be used with non-armored cables.

[0080] The housing 102 may be designed and manufactured with thermal management considerations 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 fully or partially explosion proof in compliance with applicable standards for hazardous locations, albeit providing a relatively smaller and more economical enclosure than a conventional, larger, and separately provided explosion proof enclosure, which would typically contain the entire circuit protection device. The housing 102 and any enclosures it defines may also include a vacuum chamber, or may be filled with a dielectric fluid, dielectric material, or inert gas to reduce or prevent arcing at the terminal / cable interface or other locations of the housing.

[0081] To address the potential for static charge buildup, which can present a potential 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 charges 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.

[0082] 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 an earth ground or chassis ground via a line wire or line conductor that is connected to the outer surface of the housing 102. In this way, any charging on the exterior of the housing 102 will be quickly dissipated to ground as an electric current and avoid high voltage discharge events, which are typically manifested as sparks or shocks that may be generated by a person or tool used by a person, which may otherwise occur in the presence of an explosive atmosphere and lead to ignition.

[0083] 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.

[0084] Although Figure 2 100, 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 the ground conductor connected to the exterior of the device housing 102 as described above, a ground conductor 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.

[0085] In NEC Section 2 locations or IEC Zone 1 or 2 locations, the device 100 will typically be protected by an enclosure and therefore will not be susceptible to static electricity issues and discharge events. Therefore, 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 be considered optional. However, with the device 100, the enclosure containing one or more devices 100 need not be explosion proof, and conventionally provided explosion proof enclosures may be omitted.

[0086] Figure 3is 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).

[0087] As used herein, the term "processor-based" microcontroller shall refer not only to controller devices that include the processor or microprocessor shown, but also to other equivalent components such as microcomputers, programmable logic controllers, reduced instruction set Circuits (RISC), 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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 terminate the current flow 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.

[0092] 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 .

[0093] 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 algorithm control features are programmed and stored in the device memory.

[0094] Also included is a communication element 164 that can transmit data to a remote location, as well as other devices 100 as further described below, to assess 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.

[0095] 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.

[0096] Because the solid-state device 100 does not include mechanical switch contacts for connecting and disconnecting the load-side circuit through the device 100, it is generally incompatible with conventional safety lockout or safety tagout features commonly used in mechanically actuated switch devices to ensure that workers remain disconnected while performing maintenance or service tasks on the load side of the device 100. The safety lockout or safety tagout features avoid the risk of possible electrical cutting to the worker by preventing reconnection of the load-side circuit through the device 100 unless prohibition procedures are followed.

[0097] As conventionally implemented, the mechanically actuated disconnect device is physically locked out by a padlock or other mechanical locking device in a manner that physically prevents closing of the mechanically actuated disconnect device until maintenance or servicing tasks are completed to ensure worker safety on the load side of the device. Typically, access to a mechanical unlocking device, such as a key or special tool required to unlock the device and allow reclosing of the mechanical switch contacts in the device, is typically limited to only one or more specific personnel with regulatory authorization and specific training to properly complete a safety tagout procedure to unlock the device to reclose the circuit.

[0098] Likewise, and as is conventionally implemented, in some cases, multiple physical locks are used in combination to mechanically lock a conventional mechanically actuated switch device in an open position to prevent the mechanical switch contacts from being reclosed while a maintenance procedure is performed. Each of the physical locks provided can be unlocked or tagged out only by a different person having a unique key, such that a combination of persons is required to remove all of the locks before the device can be reclosed. Such conventional safety lockout / tagout procedures using physical locking devices can effectively ensure that conventional mechanically actuated devices are not inadvertently or unintentionally closed when maintenance tasks are completed.

[0099] By eliminating the mechanically actuated switch contacts of conventional devices, the device 100 thus requires a new lockout / tagout feature and associated safe operating mode to provide a substantial degree of lockout / tagout safety assurance to ensure worker safety and manage ignition risks in hazardous locations. The device 100 thus includes a lockout component that is Figure 3 100 as a lockout component 166. As described below, the lockout component 166 may correspond to one or more lockout components that may be monitored by the processor 150, implemented electronically via the processor 150 and the device controls, or electronically assisted or confirmed by the processor 150 and the device 100 controls, respectively.

[0100] The lockout component 166 and corresponding lockout components when described in the context of and in conjunction with the device 100 below are different from conventional devices, which are advantageously designed to achieve enhanced safety when operating in hazardous locations. The benefits and advantages of the lockout components described herein extend more generally to other types of switch disconnect devices and end-use applications that pose similar electrical cutting risks or ignition risks in the maintenance of electrical loads and load-side circuits, which require safety lockouts or safety tagout features or make safety lockout / tagout features and procedures desirable.

[0101] Therefore, the device 100 including the lockout components of the invention disclosed herein is provided primarily for illustration and not limitation. The lockout components described herein can generally be used for any circuit protection device or disconnect device desired to meet applicable standards and regulations related to worker safety in and around energized power systems. Such standards and regulations may only include, for example, OSHA safety requirements for "Hazardous Energy Control" (29 CFR 1910.147) and NFPA standards 70E and 79, which provide guidance to verify that any stored energy has been properly eliminated or controlled to ensure that personnel will not be injured or exposed to electrical or mechanical energy when performing tasks. Remote actuation of circuit protection devices, disconnect devices, and switch devices creates an additional risk that personnel performing device maintenance in the absence of a lockout device may be electrically cut, so regardless of the type of input, the lockout provisions must prevent all opportunities for energizing the circuit.

[0102] Figure 4 is a front view of circuit protection device 100 illustrating exemplary safety lockout components that may be used alone or in combination to implement safe safety lockout features and functions. Figure 5 is an end view of circuit protection device 100 with an exemplary safety lockout component engaged. Figure 6 is an end view of circuit protection device 100 in a connected state with an exemplary safety lockout feature disengaged. With the provided lockout components and features, device 100 can be securely held or maintained in a disconnected or open circuit state via the lockout components, wherein the load side circuit is electrically isolated from the line side circuit by a solid state switch in device 100. When device 100 is in a lockout state, mode, or condition, device 100 cannot be inadvertently reconnected to its connected state while a worker performs required tasks on the electrical load and load side circuit connected through device 100 unless prescribed tagout procedures are followed. Safety assurance is thus provided that device 100 remains disconnected until maintenance tasks on the load side of device 100 are completed.

[0103] like Figures 4 to 6 As shown, the front face 180 of the device 100 includes the display 116 and a mechanical toggle switch 182 adjacent to the display 116. In contemplated embodiments, either the display 116 or the toggle switch 182 may be used to effect an on / off change of state of a solid-state switching element in the device 100, but in some embodiments, the device 100 may alternatively be provided with one or the other of the display 116 and the toggle switch 182, but not both.

[0104] The mechanical toggle switch 182 is selectively positionable between positions designated "on" and "off" on the front face 182 of the device. More specifically, the mechanical toggle switch 182 in the illustrated example is rotatable less than 180° relative to one another about the axis of rotation of the mechanical toggle switch 182 between positions designated "on" and "off" (although embodiments are contemplated in which the toggle switch is rotatable by approximately 90° or even less). The "on" position in the contemplated example is Figure 6 is shown in and Figure 5 is shown by a dotted line, and Figure 4 and Figure 5 The toggle switch 182 is shown in the "off" position. The toggle switch 182 serves as an intuitive and easy to use mechanical input selector for the user to turn the device on or off as desired, while also providing a visual indication to the user whether the device 100 is on or off based on the position of the mechanical toggle switch 182.

[0105] The mechanical toggle switch 182 mimics the on / off operation of known devices that include similar toggle switch input selectors, but without any mechanical actuation of the switch contacts. Thus, repositioning of the mechanical toggle switch 182 in the device 100 does not cause any mechanical actuation of the mechanical switch contacts because no mechanical switch contacts are provided in the device 100. Additionally, repositioning of the mechanical toggle switch 182 does not directly operate the solid-state switches in the device 100 to achieve the desired disconnect (breaking) or connect (connect) functionality. Instead, the mechanical toggle switch 182 serves only as a user input to the electronic controls of the device 100 to effectuate an electronic state change of the solid-state switches within the device 100 to achieve the desired on / off or connect / disconnect functionality. Based on the position of the toggle switch 182, the position of the toggle switch may be sensed, otherwise detected, or transmitted to the processor 150 ( Figure 3 ) provides control input. The processor 150 or device controller applies (or does not apply) sufficient gate-emitter voltage to the solid-state switching element in response to the toggle switch position to conduct current (or not conduct current) and achieve the desired on or connected state, or alternatively achieve the desired off or disconnected state depending on the position of the toggle switch.

[0106] The mechanical toggle switch 182 can be securely locked to an anchoring element 184 disposed in the device 100 at its distal end in the off position and protrude upward from the front face 180 adjacent the distal end of the toggle switch 182 when in the off position. Specifically, the distal end of the toggle switch 182 may include a second locking hole 186 ( Figure 5 and Figure 6 ) aligned with the first locking hole 185 ( Figure 6 When the lock holes 185, 186 are aligned, a locking element such as a handle 188 of a padlock 190 (in Figure 4and Figure 5 The mechanical toggle switch 182 is inserted through the aligned locking holes 185, 186 to physically lock the mechanical toggle switch 182 in the off position. The locked mechanical toggle switch 182 is an effective safety lockout device for the device 100 to ensure that the device 100 remains in the off state, thereby electrically isolating the load side of the device 100 from the line side circuit.

[0107] In contemplated embodiments, the anchoring element 184 may be provided as a metal plate or reinforced plastic element that is securely mounted to the device 100 and has sufficient structural strength to resist any attempt to remove the lock by force. More than one anchoring element 184 may be provided as desired to further improve the latching arrangement. While an exemplary anchoring element 184 is shown and described, other anchoring elements are possible in additional and / or alternative embodiments, where the end result is to securely lock the on / off input selector in the off position to prevent the device 100 from being re-connected.

[0108] With the exemplary toggle switch 182 and anchoring element 184, the device 100 can be securely locked as described above to ensure that the device 100 ensures the safety of workers who pay attention to the load-side maintenance procedures. The padlock 190 can only be engaged by authorized personnel with a key to unlock the toggle switch 182, so that personnel without the key cannot engage the device 100 via the toggle switch 182 locked in the off position. Although the toggle switch 182 and padlock 190 are described and shown to achieve a simple locking arrangement, an on / off input selector other than a toggle switch and a locking element other than a padlock can also be used to achieve a mechanical lockout for other non-mechanical properties of the solid-state device 100 in a switch breaking operation.

[0109] As mentioned, the mechanical toggle switch 182 can be used as a stand-alone on / off switch input selector including a safety lockout capability, or can be used in conjunction with the display 116. When the toggle switch 182 and the display 116 are provided separately, the display 116 can provide visual user feedback to the user when the toggle switch 182 moves between the on and off positions, and provide the user with another visual prompt as to whether the state of the device is on / connected or disconnected / disconnected. Specifically, when the mechanical toggle switch 182 moves to the on position, the processor 150 can operate the solid-state switch to conduct current, confirm that current is being conducted through a sensor disposed in the device 100, and cause an on indicator to appear on the display 116 to confirm to the user that the device 100 is actually on. In addition, when the mechanical toggle switch 182 moves to the off position, the processor 150 can operate the solid-state switch to become non-conductive, confirm that the load-side terminals are electrically isolated through a sensor disposed in the device 100, and cause an off indicator to appear on the display 116 to confirm to the user that the device 100 is actually disconnected.

[0110] When confirmation of the actual on or off state of the device 100 is provided to the user, additional safety is provided in the event of a device control failure or a solid-state switch failure. In this case, the mechanical toggle switch 182 may be moved to the off position, but the solid-state switch remains "on" to conduct current to the load side. In response to such a condition, which may be detected by a load-side sensor on the device 100, the display 116 may provide a clear warning on the display 116 that the device 100 is not actually "off" as the user expected by moving the toggle switch 182 to the on or off position. Alerts and notifications of error conditions may also be generated for the device 100, and if necessary, the line-side circuit may be locally or remotely electrically isolated via operation of an upstream switch device in the power system to ensure the safety of workers while completing required load-side tasks.

[0111] While the confirmation on / off status indication is described via the display 116, indicator lights and other confirmation / feedback features may also be used to provide confirmation to the user of the actual state of the solid-state switch (e.g., on or off), or to effectively alert the user of a detected device error or malfunction (in addition to or in lieu of the display 116). In some embodiments, an audio alert feature may be provided as an enhanced confirmation or warning feature using a verbal message such as "device is on," "device is off," or "warning, device remains on," "warning, device remains off." Confirmation or warning data messages may also be automatically generated and transmitted to a remote device for system-level assurance, analysis, and record keeping purposes to record connections and disconnections made by the device, the times of connections and disconnections, sensor and mechanical toggle switch states, or other data of interest.

[0112] In embodiments that do not necessarily include a mechanical toggle switch 182, the display 116 may be touch sensitive and may define an on / off button 192, a safety lockout button 194, and a lockout deactivation element 196. The on / off button 192 may be used for a normal on / off change of state operation of the device 100, wherein the controls of the device 100 thus control a solid-state switch without the need for a toggle switch 182 or other mechanical input selector. Audio and / or visual feedback may be provided to the user confirming that the device 100 is actually on or off, or that an error has been detected alerting the appropriate.

[0113] When the display 116 is a touch-sensitive display, graphical icons may be provided in the main screen display and subsequent displays as the user makes input selections, and user interface selections may be provided in menus or submenus. A home screen button may be provided adjacent to the display 116, and an on / off switch may be provided on the main display for easy access. The user may touch, swipe, or utilize other forms of contact to operate the display 116 in an easy-to-use display-driven interface in the style of other types of smart devices (e.g., smart phones or tablet computers). When the user disconnects the device 100 via the on / off input selector in the main screen, another screen display including a safety lockout button 194 may be presented. Similarly, when the safety lockout button 194 is activated, another screen display including a lockout deactivation element 196 may be presented. There may be many variations in this regard.

[0114] When a mechanical toggle switch 182 is provided in addition to the display 116, a separate or independent on / off button 192 in the display 116 may be considered optional and need not be included. When the mechanical toggle switch 182 is moved to its on or off position, the display 116 may automatically switch to a different screen display including an on or off confirmation so that the user can see the device 100 in response to the position of the mechanical toggle switch 182 selected by the user. When the lockout is activated, the toggle switch 182 may be disabled from a control perspective to further ensure that it cannot be used to turn the device back on until the electronic lockout condition is properly deactivated as discussed below.

[0115] In contemplated embodiments where the display 116 is not a touch sensitive display, additional input selectors may be provided in the form of buttons or any alternative form desired by the user to select or make the on / off input, the safety lockout input, and the lockout deactivation input independently of or in combination with the display 116. In contemplated embodiments, in a menu driven user interface, the additional input buttons may be multifunctional and coordinated with the screen display for intuitive device operation by the user in the main screen and related screens to select different options, or the input buttons may be provided with labels or the like, wherein each input button is used for only one purpose (e.g., on / off selection).

[0116] When desired, the safety lockout button 194 (or corresponding input selector) can be manipulated by the user to activate the electronic lockout feature, wherein the on / off button 192 (or other corresponding input selector including but not limited to the toggle switch 182) is disabled, so that any further user manipulation of the on / off button 192 (or other corresponding input selector) cannot effectively change the state of the solid-state switch in the device 100. Therefore, when the device 100 is turned off and when the lockout is enabled, the device controls will ignore any attempt by the user to turn the device 100 back on via the on / off input selector. As previously described, the actual change in state of the solid-state switch in the device 100 (as detected by the sensor in the device 100) can be visually confirmed for the benefit of the user, and a safety warning or error notification regarding a possible error condition or failure of the device 100 can be made via the device 116. The display 116 can also visually indicate to the user that the lockout has been activated, and an audio confirmation can also be provided.

[0117] Once the lockout button 194 is activated on the display 116, the device 100 remains in the locked state and may not be turned back on until the lockout deactivation element 196 is properly used to tag out the lockout element and deactivate the lockout feature. In one example, when the user selects the lockout deactivation element 196, the user is presented with a screen to enter the tagout code. Of course, in contemplated embodiments, the tagout code will only be known to one or more designated personnel who are authorized to turn the device back on and thus reclose the device for the purpose of restoring operation of the power system on the load side of the device 100. Unless the correct tagout code is presented, the lockout will not be deactivated and the on / off input selector will continue to be disabled and any use thereof to attempt to turn the device on will be ignored.

[0118] Such exemplary lockout activation and tagout deactivation features implemented electronically through the display 116 and controls of the device 100 may supplement the toggle lockout described above or may be used as a standalone feature. Although the password deactivation feature has been described for an electronic lock, other known features for verifying the authority of a person or known and available for use include, but are not limited to, known biometric elements for identifying a fingerprint of an authorized person, etc., to unlock the device interface and / or deactivate the security lockout.

[0119] When the mechanical toggle switch 182 and the display 116 are each present in the device 100, an enhanced lockout / tagout procedure is possible with greater assurance of safety than would be possible if only one of them were provided. For example, one person may be required to unlock an electronic feature enabled by the display 116 with a required code, and another person may be required to unlock the padlock 190 with a required key to release the otherwise locked toggle switch 182 so that it can be moved to the on position to turn the device 100 back on. If the mechanical lock is disabled to release the toggle switch 182, but the electronic lock remains activated (or vice versa), the controls in the device 100 will not allow the device to be turned back on. Such a multi-step lockout / tagout procedure involving different personnel is desirable in hazardous locations to reduce any possibility of human error in operating the switches, and thus increase worker safety and possible ignition issues if the device 100 is turned back on before maintenance tasks are completed on the load side of the device 100.

[0120] As yet another locking feature to provide lockout / tagout security, the front face 180 of the device 100 also includes a pair of respectively formed locking openings 200, 202 that are sized and spaced apart from one another to receive a physical mechanical locking element, such as a handle 204 of a padlock 206 (in the middle of the lockout openings 200, 202) through and between each of the locking openings 200, 202. Figure 4 and Figure 5 Provide lock detection sensors 208, 210 (in Figure 5 208, 210) to detect the insertion of a locking element (e.g., handle 204), and when the insertion of the handle 204 is detected, the controls of the device 100 can disable the on / off input selector to present a locked state or condition. Thus, the mechanical action of the user inserting the handle 204 serves as an electronic control input via the lock detection sensors 208, 210, which in turn causes the device 100 to present a secure locked state.

[0121] In the envisioned embodiment, the lock detection sensors 208, 210 may be optical sensors or limit switches in the envisioned examples, but other types of sensors are possible in additional and / or alternative embodiments. Optionally, the lock detection sensors 208, 210 may be controlled so that they are powered only when the on / off switch is in the "off" position, thereby avoiding unnecessary power consumption when the device 100 is turned on with the on / off switch in the "on" position. Thus, the lockout can only be activated via insertion of the lock after the device 100 has been turned off. This prevents potentially problematic lockout activation when the device 100 is turned on, and prevents the resulting lockout or prevents the user from disconnecting the device 100 without first undergoing a prescribed lockout deactivation, which may only be done by certain users for the reasons described above. While in some cases, the lockout of the device 100 in the on state may provide a desired safety feature, thereby protecting critical loads from being accidentally disconnected by unauthorized persons, such a lockout is an optional feature in some embodiments to ensure that the device remains on or connected, although it is not desirable in some cases. In particular, when operating in hazardous locations, being able to quickly shut down the device 100 and disconnect the load side when needed, without restriction and without time delay to deactivate the provided lockout, is important and should not be hindered, so that the safety lockout components are usually reserved only for the off or disconnected state of the device 100 in the hazardous location. However, provided that there are sufficient emergency override or lockout bypass features to allow the device 100 to be easily disconnected, even if it has been advantageously locked in the on or connected state, such lockouts may be permissible in the on state.

[0122] Once the lock is detected by the sensors 208, 210, the device 100 remains disconnected in the locked state, with the on / off input selector disabled, as long as the lock remains in place. The padlock 206 can only be accessed by an authorized person with a key to remove the handle 204, so that a person without the key cannot remove the handle 204. Removal of the handle 204 by a designated person is also detected by the sensors 208, 210, causing the device control to deactivate the lock and allow the device 100 to be turned on again via the on / off input selector.

[0123] The automatic lock detection and associated lockout / tagout features may be used as stand-alone features or in combination with one or both of the mechanical toggle switch and electronic display driven lockout features described above. As described above, confirmation of a successful lockout operation and user feedback may be provided, as well as notification of errors or failures. When all three of the described lockout features are provided in combination, a redundant three-step lockout / tagout procedure is facilitated, which may involve three different personnel disabling each type of lockout provided. The automatic lock detection and security lockout / tagout features may likewise be provided with either but not both of the other features described above to facilitate a two-step security lockout / tagout procedure, which may involve two different personnel disabling each type of lockout provided.

[0124] Although exemplary mechanical and electronic safety lockout / tagout components and methods have been described and illustrated, further adjustments are possible. For example, a mechanical locking element other than a padlock can be used to lock a mechanical input selector such as a toggle switch 182 in an off position and / or inserted through a lock opening in the device 100. Likewise, other types of lock detection sensors can detect other types of mechanical locking elements. Various forms of electronic lockouts can be provided using different user interfaces and safety features to ensure that safety lockouts are successful for solid-state devices 100 that do not include mechanically actuated switches, while ensuring that safety lockouts can only be deactivated by authorized personnel, and also ensuring that additional ignition issues in hazardous locations are fully addressed in the operation of the device 100.

[0125] Figure 7 is an exemplary algorithmic flow chart of a safety lockout activation and deactivation procedure 230 for the device 100. The algorithmic procedure may be implemented, for example, by a processor-based control including the processor 150 and applicable sensors included in the device controls, or by an equivalent controller based on various sensors provided to detect the state or position of mechanical or electronic input selectors as they relate to voltage or current readings at various locations in the device, as well as other considerations discussed below.

[0126] At step 232, an on / off input element in the monitoring device 100, such as a toggle switch 182 ( Figures 4 to 6 ) or other input selector. At step 234, it is determined whether the on / off switch is in the off position as an input selection intended by the user to disconnect the device 100 to achieve disconnection of the load-side circuit and the electrical load by the device 100. When a non-mechanical input selector is provided, at step 232, when the user selects the input element to change the state of the device from on to off or from off to on, the activation of the input element can be monitored.

[0127] If at step 234, the on / off input element is not in the off position, the algorithm returns to step 232 and continues to monitor the on / off input element. Unless the on / off input selector is determined to be "off," it can be assumed that normal "on" operation of the device 100 connecting the line-side circuit and the load-side circuit through the device 100 is desired and no further action is required.

[0128] If it is determined at step 234 that the on / off input selection is "off", the device proceeds to operate the solid-state switch at step 236 to become non-conductive so that current can no longer flow through the solid-state switch to the load-side terminals and achieve the desired disconnection. For the purposes of step 236, operation of the solid-state switch refers to the operating controls and actions required to affect the state change of the provided solid-state switch from the current conducting state to the non-current conducting state. For example, operation of the solid-state switch refers to the voltage change necessary for the gate-emitter of the solid-state switch to reach the non-conductive state of each solid-state switch.

[0129] At step 238, the processor 150 may confirm whether the load-side terminals of the device 100 are actually electrically isolated and de-energized via sensors disposed in the device 100. For example, if truly isolated as desired, the load-side terminals of the device 100 will have zero voltage and zero current detection from applicable sensors. If non-zero voltage and current are found to be present, the load-side terminals of the device 100 are not isolated as expected, and at step 266, the processor may generate a notification or alert to the local user interface (e.g., the display 116 described above) and any associated remote user interfaces. At step 268, feedback is provided to the user to visually display to the user that the device 100 remains on and is not disconnected. The user's observation of the provided feedback will therefore see that there is a problem with the device 100 that requires attention so that the load-side circuit is actually disconnected as expected.

[0130] If the processor 152 confirms at step 238 that the load-side terminals of the device 100 are in fact electrically isolated and de-energized, a prompt may be presented at step 240 on the local user interface (e.g., display 116) as to whether a safety lockout is required. If not, the algorithm returns to step 232 and may continue to check to see if isolation is maintained. The algorithm thus confirms that disconnection may be required at times, but a safety lockout is not required because disconnection is not performed in accordance with a maintenance or service task to be performed on the load side. The prompt at step 240 also reminds the user that a safety lockout is available if required, but needs to be activated by the user.

[0131] If a safety lockout is required at step 240, lockout instructions may be presented to the user at step 242, such as inserting and installing a locking element as described above with respect to an exemplary padlock. Where multiple different types of lockout components are provided, step-by-step lockout instructions may be provided. At step 244, installation of the lock as indicated may be detected, and in response to the detection, the on / off input element may be deactivated or disabled so that the on / off input element is not responsive to actually turning the device 100 back on and effecting a change in state of the solid-state switch element. At step 248, a confirmation may be provided to the user that the safety lockout has been successfully activated. The worker may thus safely continue to perform tasks on the electrical load and load-side circuits.

[0132] At step 250, the device waits for completion of the load-side procedure being executed, continues to confirm that electrical isolation is maintained, and provides confirmation of lockout activation. At step 252, instructions may be provided to the user to deactivate the safety lockout in order to turn the device back on, including removing any mechanical locks or deactivating electronic locks. Step-by-step lockout deactivation instructions may be provided for each type of lockout component provided in the device 100.

[0133] At step 254, mechanical lock removal may be detected. At step 256, user authentication or authorization to disable any electronic locks, such as the password described above, is received. If, at step 258, it is determined that the received authentication is authorized, then at step 260, deactivation of the safety lockout event is recorded. At step 262, the on / off input element is reactivated. The user may now reclose the device using the on / off input element, and in response, the device controls will operate the solid-state switch to become conductive and reconnect the load-side circuit through the device 100.

[0134] If at step 258, the received verification is not authorized, a notification or alert is generated to the remote device and person that a potentially improper attempt has been made to reclose the device 100. Such a situation may therefore be investigated.

[0135] Depending on the type and number of latching components and features provided in the device 100, it is now believed that appropriate modifications to the algorithms and procedures shown and described will be apparent. If some of the above-mentioned latching types are not provided in the device 100, certain steps shown and described will not be performed. Likewise, additional steps may be taken to accommodate additional types of latches or additional latching features as needed. Although specific examples of processes are set forth above with respect to exemplary embodiments, similar effects and benefits may be achieved in other ways using other equivalent processes to accommodate additional or alternative mechanical locking features, various types of local and remote user interfaces, various different types of sensors for detecting mechanical locking elements, and various forms of user authorization and authentication.

[0136] Figure 8 is a perspective view of a compliant explosive location circuit protection device 300 according to another exemplary embodiment of the present invention. The circuit protection device 300 includes the housing 102 described above, and the housing 102 described has the chemical resistance, impact resistance and thermal management features described above with respect to the device 100, but omits the digital display 116 ( Figure 1 ).like Figure 8 As shown, a user can access a mechanical toggle switch 302 on the upper front portion of the housing 102 to manually activate the device 300 between an "on" and "off" state, 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 may be employed. In some cases, a display 116 may be provided in addition to or as a replacement for the toggle switch 302 or another manual actuator. Any of the above-described safety lockout features may be used in the device 100 alone or in combination.

[0137] Similar to the device 100, the 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). The 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. The device 300 can operate according to a specified time-current curve or time-current profile suitable for providing adequate protection for the connected load.

[0138] Fig. 9 1 is a simplified schematic diagram of a circuit protection device 130 in an exemplary hybrid configuration. The device 300 includes input terminals 130a, 130b, 130c, each connected via a connecting cable or conduit to one phase of a three-phase power source indicated as line-side circuit 132. The device 300 also includes output terminals 134a, 134b, 136c, each connected to a load-side circuit 136, such as motors, fans, lighting, and other electrical devices in an industrial facility where ignitable gases, vapors, or substances may be airborne as indicated at 138 to create an explosive environment.

[0139] Between each pair of input terminals 130a, 130b and 130c and output terminals 134a, 134b and 136c are mechanical circuit breakers 304a, 304b and 304c and solid-state switch devices connected in parallel, the arrangements of which are shown as 140a, 140b and 140c. The exemplary solid-state switch arrangements 140a, 140b and 140c include pairs of insulated gate bipolar transistors (IGBTs) connected in series, wherein, as described above, each pair includes a varistor element connected in parallel to the IGBT. Although exemplary solid-state switch arrangements are shown and described, other arrangements may also implement solid-state switch functions in an arc-free manner. As described above, the solid-state switch devices operate in an arc-free manner, so the solid-state switch devices themselves do not pose an ignition risk in hazardous locations in terms of arc discharge.

[0140] The combination of mechanical circuit breakers 304a, 304b, and 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, and 304c can limit the current in the mechanical circuit breakers 304a, 304, and 304c during 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] 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.

[0142] The device 300 is also connected to the electrical ground 146 to dissipate any charging of the housing surface as described above, thereby eliminating a possible ignition source via electrostatic discharge. The line and load side connections may be made using safety terminal assemblies including, but not limited to, locking terminal features to prevent loose connections over time after initial fastening with fasteners, and connections to enclosed terminals via armored cables and cable glands to provide enhanced safety for explosive environments.

[0143] Fig.10is a block diagram of a circuit protection device 300 which, in addition to the above elements of 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.

[0144] In the case of the device 300, a toggle switch input element 302 that includes a mechanically actuated switch contact, thus causing the mechanical switch contact to open and close, can be mechanically locked in an open position to achieve a safe safety lockout for the mechanical switch contacts in the device. As described above, confirmation and feedback can be provided to the user that the mechanical switch contacts are actually connected to electrically isolate the load-side terminals. The sensor in the device 300 can also confirm that the electronic solid-state switch is non-conductive and that the load-side terminals of the device are electrically isolated as required. If the mechanical switch contacts are connected but the electronic solid-state switch remains conductive, an error condition can be detected, and a warning and alert that an error condition exists or a device failure has been detected can be advantageously generated. Multi-step safety lockout deactivation can be achieved as described above for redundant safety levels, where multiple personnel are involved in different aspects to enhance the safety lockout / tagout procedure, and also achieve greater safety assurance for the operation of the device 300 in hazardous locations and optionally in non-hazardous locations.

[0145] When a predetermined overcurrent condition occurs, 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.

[0146] Although an exemplary device architecture of device 300 has been described, it should be understood that Fig.10 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.11 It shows schematically Figures 8 to 10 Thermal management features of the circuit protection device shown. While hybrid device 300 is capable of operating in an arc-free manner in many situations as described above, 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, additional considerations must be taken to address any arcing that occurs.

[0148] like Fig.11As shown, in 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 circuit breaker is isolated from the surrounding environment or otherwise reduced to levels insufficient to cause ignition in an explosive location. Fig.11 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 and 322c. The secondary enclosure 322 is 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 and 322c and therefore cannot be ignited by the operation of the mechanical circuit breaker.

[0149] In the envisioned embodiment, the secondary housings 322a, 322b, and 322c can be airtight sealed chambers that include the corresponding switch contacts. The airtight sealed chambers 322a, 322b, and 322c are fluid-tight so that any ignitable elements that can penetrate the housing 102 into the hazardous location of the primary housing 102 cannot enter the sealed chambers 322a, 322b, and 322c. The airtight sealed chambers can also be vacuum chambers or filled with 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, and 322c can be provided with additional insulators and materials to control any heat associated with arcing and locate it to the secondary housings 322a, 322b, and 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 solving the additional problems of mechanical switch contacts in explosive environments.

[0150] The secondary housings 322a, 322b, and 322c may be made of a different material than the rest of the housing 102, or a combination of materials that may be the same or different than the rest of the housing. For example, a metal material and plastic may be used to construct the chamber, while the primary housing and the rest of the housing may be entirely plastic. There may be many variations in this regard. The secondary housings 322a, 322b, and 322c may be prefabricated and assembled with the housing 102 in a separate manufacturing stage. The secondary housings 322a, 322b, and 322c may enclose some or all of the mechanical circuit breaker mechanisms without obstructing the motion path of the switch contacts or their ability to move.

[0151] Each of the devices 100 or 300 can be safely used in Zone 1 or Zone 2 of the IEC or Division 1 or Division 2 of the NEC hazardous locations without the need for a conventional, separately provided explosion proof enclosure, and the enhanced safety lockout / tagout features and intelligence described above with respect to the device 100 are equally applicable to the device 300. The above-mentioned built-in anti-ignition features eliminate ignition sources or reduce them to a level insufficient to cause ignition. The device 100 or 300 is therefore 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 otherwise be safely controlled by setting up a conventional explosion proof enclosure. Therefore, the devices 100 and 300 can be safely operated in explosive locations, and the cost and burden of conventional explosion proof enclosures are eliminated, while saving space in the power system.

[0152] Fig.12 An exemplary switchboard 400 including a compliant hazardous location circuit protection device is shown, the circuit protection device including an array of devices 402, 404 arranged in two columns of devices. The devices 402, 404 in each column include the devices 100 or 300 described above, and the devices 402, 404 can be represented by different ratings, which provide different degrees of circuit protection for the various different loads served by the switchboard and its various branches. The switchboard 400 typically includes its own enclosure, but because of the anti-ignition devices 402, 404 used on the switchboard, the enclosure of the switchboard itself can be a standard enclosure that is not designed to be explosion-proof. Because the devices 402, 404 are ignition-proof, they can be present in the switchboard enclosure without the need for a conventional explosion-proof enclosure in the switchboard enclosure. The switchboard enclosure protects the devices 402, 404 from environmental conditions, but 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 separately provided individual explosion proof enclosures and common explosion proof enclosures significantly reduces the cost of operating devices 402, 404 in hazardous locations. For large power systems including multiple switchboards located at different locations, the cost is multiplied even further.

[0153] Safety lockout features such as those described above can be implemented at the system level in a switchboard assembly. For example, a separate user interface can be provided relative to the switchboard, and the above-mentioned types of mechanical lockouts and electronic lockouts can be used to act on or through the switchboard user interface to disconnect all devices 402, 404, as shown, and lock all devices 402, 404 in the group via the switchboard user interface when necessary, thereby eliminating any need that may otherwise exist for individually disconnecting and locking each of the devices 402, 404. Similarly, group deactivation of the safety lockout feature is possible, and the group of devices 402, 404 can be reconnected together via the switchboard user interface. In addition, such a switchboard user interface can display the on / off state or lockout state of each device 402, 404 individually or in groups. Insofar as the devices 400, 402 can be advantageously used individually to disconnect only selected electrical loads among the connected electrical loads through the individual devices 402, 404 in the panel, the switchboard user interface can also present the status of the devices 402, 404 and confirmation of the status. For example, considering n circuits connected through a panel, circuits 1, 7, 12, and 19 in the panel can be locked with a single lock (implemented by the panel rather than separate devices) via selected devices 402, 404, while preventing the devices from being closed to energize circuits 1, 7, 12, and 19.

[0154] In such a switchboard installation including multiple devices 402, 404 operating simultaneously and in close proximity to each other, the thermal management problem of device operation in a hazardous location is further multiplied. Thermal effects can accumulate, and adjacent devices can be hotter (i.e., have a higher surface temperature) when operating than when they are used alone or at least spaced farther apart from each other. When the switchboard includes an enclosure, which does not necessarily require an explosion-proof enclosure, when heat rises from the devices 402, 404 located below, the devices 402, 404 in the upper part of the column can be hotter when operating than the devices 402, 404 in the lower part of the enclosure. Then, in some cases, 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. The active cooling system may be triggered by ambient temperature sensing, temperature readings from any of the temperature sensors disposed in devices 402, 404, or other factors and considerations to operate only as needed, or may alternatively operate continuously or intermittently as needed.

[0155] While a switchboard and switchboard enclosure are described above for devices 402, 404, similar benefits may be realized in motor control centers and other locations in power systems where circuit protection devices 402, 404 are also conventionally located in non-explosion proof enclosures. Given the sensors and intelligence provided in devices 402, 404 and the motor inrush features provided in devices 402, 404, additional motor starting components may be integrated into the design of devices 402, 404 and a combination circuit protector / motor starter provided in a single package, as opposed to conventionally provided separately packaged and serially connected circuit protectors and motor starter assemblies, each of which requires an explosion proof enclosure for use in hazardous locations. Other dual-purpose or dual-function devices 402, 404 are also possible, further reducing the cost of installing and maintaining the power system by reducing the number of devices that need to be acquired, installed, and maintained in the power system.

[0156] Solid-state or hybrid devices (such as those described above) can be constructed using a variety of different solid-state switching elements, 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, 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 necessary. Solid-state switching elements can be connected in series or in parallel using modular arrangements 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.

[0157] 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 assurance by addressing any deficiencies or solid-state switch elements with respect to certain overcurrent conditions, or to improve response time to certain operating conditions.

[0158] The above-described device construction and safety lockout / tagout features can be readily applied to implement circuit protection devices that are not circuit breaker devices, but are still ignition proof for use in NEC Division 1 or 2 hazardous locations and IEC Zone 1 or 2 locations without an explosion proof enclosure. For example, a fusible switch disconnect device is discussed above, which includes a mechanical switch combined with a fuse. Applying the described chemical and impact resistant housing construction, arc-free switching operation, safety terminal assembly, and thermal management features, a solid-state fusible switch disconnect device or a hybrid fusible switch disconnect device can be readily constructed to have similar benefits, but provide different degrees of circuit protection.

[0159] Likewise, the chemically resistant and impact resistant housing construction, arc-free switching operation, safety lockout / tagout features, and certain thermal management features described above can be readily applied to implement a switchgear that does not itself provide overcurrent circuit protection, but is still ignition proof for use in NEC Division 1 or 2 hazardous locations and IEC Zone 1 or 2 locations without a separately provided 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 independently operate and protect against overcurrent conditions. Applying the chemically resistant and impact resistant housing construction, arc-free switching operation, safety lockout / tagout features, and thermal management features described above, a solid-state relay device or hybrid relay device and a solid-state contactor device or hybrid contactor device can be readily constructed to safely operate in an explosive environment with intelligent lockout detection capability, lockout detection, and confirmation.

[0160] Anti-ignition devices such as those described may 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 functionality for use in NEC Section 1 or Section 2 locations or IEC Zone 1 or Zone 2 hazardous locations.

[0161] 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.

[0162] It is now believed that the benefits and advantages of the inventive concepts have been fully demonstrated in accordance with the disclosed exemplary embodiments.

[0163] Embodiments of a compliant switchgear for use in hazardous locations have been disclosed. The compliant switchgear includes an ignition-proof housing, a line-side terminal and a load-side terminal coupled to the housing, and a bus structure located in the housing and including at least one solid-state switch element, the at least one solid-state switch element being operable in an arc-free manner to connect the load-side terminal to the line-side terminal and disconnect the load-side terminal from the line-side terminal. The switchgear also includes an on / off input selector for changing the state of the at least one solid-state switch element, and a controller for monitoring the state of the on / off input selector, and in response to a change in the state of the lockout input selector, the controller is configured to activate a safety lockout condition that disables the on / off input selector and prevents a change in the state of the at least one solid-state switch element via the on / off input selector, whereby the switchgear is compliant for use in an explosive environment without requiring a separately provided explosion-proof enclosure.

[0164] Optionally, the controller may also be configured to confirm a change in state of at least one solid-state switch element and provide confirmation of the changed state to a user. The on / off input selector may be a mechanical input selector, and more specifically, may be a mechanical toggle switch that may be secured in an off position via a mechanical locking element such as a padlock.

[0165] As a further option, the on / off input selector may be incorporated into the electronic display.The controller may be configured to deactivate the security lockout condition when a user provides a predetermined code.

[0166] Optionally, the switch device may include a detector that senses the presence or absence of a mechanical lock element for safety lockout. The detector may be configured to sense the presence or absence of a padlock handle.

[0167] A plurality of different types of safety lockout components may be provided in the switchgear. The plurality of different types of safety lockout components may operate in combination to implement a multi-step lockout procedure. The plurality of different types of safety lockout components may include a mechanical toggle switch and a lock opening, a padlock and a detector for sensing the presence of the padlock, and a multi-function display.

[0168] The switch may also include at least one mechanical switch contact in a bus structure, and the housing may include a sealed inner housing that houses the at least one mechanical switch contact, thereby preventing the switch contact from becoming an ignition source in an explosive environment. The at least one solid-state switch element may be encapsulated. The switch device may function as a solid-state overcurrent protection device, or may be configured as a hybrid overcurrent protection device. The housing of the switch device may be electrically grounded and / or exhibit anti-static properties. The housing is chemically resistant in hazardous locations.

[0169] 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 with insubstantial differences from the literal language of the claims.

Claims

1. A compliant switch device for use in hazardous locations, the compliant switch device comprising: Ignition-proof housing; a line-side terminal and a load-side terminal coupled to the housing; a bus structure in the housing and including at least one solid-state switching element operable in an arc-free manner to connect the load-side terminals to the line-side terminals and to disconnect the load-side terminals from the line-side terminals; an on / off input selector for changing the state of the at least one solid-state switching element; a controller that monitors the state of the on / off input selector and, in response to a change in state of a lockout input selector, is configured to activate a safety lockout condition that disables the on / off input selector and prevents a change in state of the on / off input selector; The switching device is thus suitable for use in explosive atmospheres without a separately provided explosion-proof housing being necessary.

2. The switch device of claim 1, wherein the controller is further configured to confirm a change in state of the at least one solid-state switch element and provide confirmation of the changed state to a user.

3. The switch device of claim 1, wherein the on / off input selector is a mechanical input selector.

4. The switch device of claim 3, wherein the on / off input selector is a mechanical toggle switch. 5 . The switch device according to claim 4 , wherein the mechanical toggle switch can be fixed in the off position via a mechanical locking element. The switchgear according to claim 5 , wherein the mechanical locking element is a padlock.

7. The switch device of claim 1, wherein the on / off input selector is incorporated into an electronic display.

8. The switch device of claim 1, wherein the controller is configured to deactivate the safety lockout condition when a user provides a predetermined password.

9. The switch device of claim 1, further comprising a detector that senses the presence or absence of a mechanical lock element for the safety lockout.

10. The switchgear of claim 9, wherein the detector is configured to sense a padlock handle.

11. The switchgear according to claim 1, wherein a plurality of different types of safety lockout components are provided.

12. The switchgear of claim 11, wherein the plurality of different types of safety lockout components are operable in combination to implement a multi-step lockout procedure.

13. The switchgear of claim 12, wherein the plurality of different types of safety lockout components include a mechanical toggle switch and a lock opening, a padlock and a detector for sensing the presence of the padlock, and a multi-function display.

14. The switching device according to claim 1 further comprises at least one mechanical switch contact in the bus structure, and the housing comprises a sealed internal shell which accommodates the at least one mechanical switch contact, thereby preventing the switch contact from becoming an ignition source in the explosive environment.

15. The switch device of claim 1, wherein the at least one solid-state switching element is encapsulated.

16. The switch device of claim 1, wherein the device is configured as a solid-state overcurrent protection device.

17. The switching device of claim 1, wherein the device is configured as a hybrid overcurrent protection device.

18. The switchgear of claim 1, wherein the housing is electrically grounded.

19. The switch device of claim 1, wherein the housing exhibits anti-static properties.

20. The switchgear of claim 1, wherein the housing is chemically resistant in the hazardous location.

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