Abstract: A vibratory screening apparatus has a frame, a screen assembly affixed to the frame and having a screen with the plurality of spaced openings extending between outer edges of the screen, and a vibration amplifier coupled to the frame into the screen assembly. The screen assembly has a plurality of cross-members extending between sides or ends of said frame. The screen assembly has at least one screen cloth therein. The vibration amplifier is positioned directly beneath the screen assembly. The vibration amplifier is adapted to exert a force against a portion of an underside of the screen assembly.

Abstract: The present invention relates to a modular filter element comprising a first elongate hollow body, a second elongate hollow body and connection means for connecting the first elongate hollow body to the second elongate hollow body, wherein the connection means comprises a connection member that extends into a lower wall of the first elongate hollow body and into the upper wall of the second elongate hollow body to provide a gas-tight seal between the first elongate hollow body and the second elongate hollow body.

Abstract: A surface cleaning apparatus may include a cleaner body and a dust cup coupled to the cleaner body. The dust cup may be configured to pivot between at least three indexed positions.

Abstract: A uniflow cyclone for a hand vacuum cleaner has a dirt chamber that is external to the cyclone chamber and vortex finder, which has a solid portion that is spaced from and faces a dirt outlet of the cyclone chamber and a porous section that is angularly spaced around the cyclone axis of rotation of the cyclone from the solid portion.

Abstract: A wheel carrier assembly for a front axle or rear axle of a motor vehicle, with a wheel carrier part on which a link for a control arm assembly, a fixing device for a damper strut and a recess for a wheel bearing are provided. The wheel carrier part includes an air guide device for supplying air to a disk brake assembly, which as brake parts has at least a brake disk and a brake caliper. The wheel carrier part has a circumferentially hollow wheel carrier housing part. The air guide device includes at least one air inlet opening and at least one air outlet opening directed onto a brake part.

Abstract: In an example, a particulate filter includes a porous filter substrate including a first surface and a second surface. The porous filter substrate is configured to filter gas flowing through the porous filter substrate between the first surface and the second surface. A plurality of conductors are coupled to the porous filter substrate. The plurality of conductors are approximately parallel to each other along the porous filter substrate. The particulate filter also includes a plurality of input nodes in signal communication with the plurality of conductors and configured to receive a voltage signal from an input signal source. The plurality of conductors are configured to generate an electric field on at least one of the first surface or the second surface of the porous filter substrate in response to the plurality of input nodes receiving the voltage signal from the input signal source.

Abstract: In an example, a particulate filter includes a porous filter substrate including a first surface and a second surface. The porous filter substrate is configured to filter gas flowing through the porous filter substrate between the first surface and the second surface. A plurality of conductors are coupled to the porous filter substrate. The plurality of conductors are approximately parallel to each other along the porous filter substrate. The particulate filter also includes a plurality of input nodes in signal communication with the plurality of conductors and configured to receive a voltage signal from an input signal source. The plurality of conductors are configured to generate an electric field on at least one of the first surface or the second surface of the porous filter substrate in response to the plurality of input nodes receiving the voltage signal from the input signal source.

Abstract: In an example, a particulate filter includes a porous filter substrate including a first surface and a second surface. The porous filter substrate is configured to filter gas flowing through the porous filter substrate between the first surface and the second surface. A plurality of conductors are coupled to the porous filter substrate. The plurality of conductors are approximately parallel to each other along the porous filter substrate. The particulate filter also includes a plurality of input nodes in signal communication with the plurality of conductors and configured to receive a voltage signal from an input signal source. The plurality of conductors are configured to generate an electric field on at least one of the first surface or the second surface of the porous filter substrate in response to the plurality of input nodes receiving the voltage signal from the input signal source.

Abstract: The disclosed filter element is configured for use within a housing of a filter assembly. The filter element includes an obround ring of filter media extending between an upper and lower endcaps and defines a dirty wet fuel region. The upper endcap of the filter element defines an inlet for receiving the dirty wet fuel, which flows into the dirty wet fuel region and radially outward through the filter media. The upper endcap may include an insert to define a flow chamber to distribute fuel into the dirty wet fuel region. A clean wet fuel region is defined outside the filter element and within the housing. After flowing through the inlet and the filter media clean wet fuel fills the clean wet fuel region. A water separator is disposed external to the filter media and defines a clean dry fuel region in communication with an outlet defined by the upper endcap.

Abstract: A hand-guide cyclone vacuum cleaner includes: a device body which has a drive unit for generating a suction air flow; a suction container, which is connected to the device body, for receiving suction material; and an operating element arranged at one end of the suction container opposite an end of the suction container on which the device body is arranged. The operating element is rotatable from a first position into a second position and from the second position into the first position. The device body is inseparably connected to the suction container in the first position. The device body is separably connected to the suction container in the second position.

Abstract: A surface cleaning apparatus comprises a canister body having a recess with sidewalls that extend upwardly from a platform, the platform having a pre-motor filter housing with a pre-motor filter positioned therein, wherein at least 50% of a perimeter of the pre-motor filter is recessed inwardly from the sidewalls of the recess whereby, when a pre-motor filter is positioned in the pre-motor filter housing, a portion of the platform is visible between the perimeter of the pre-motor filter and the sidewalls of the recess. An air treatment assembly is removably mountable to the canister body and seats on the recess when the air treatment assembly is mounted to the canister body.

Abstract: The invention relates to an interior air filter element (10) for a driver's cabin (302) of agricultural and work machines, particularly having sprinkling or spraying devices for pesticides or fertilizers including a filter body (12) having an adsorption filter region (50) and a fine filter region (80) particularly for separating aerosols, wherein the filter body 12 is designed as a winding body having at least one winding layer.

Abstract: A surface cleaning apparatus comprises an air treatment member having a first end, a longitudinally spaced apart second end, an air inlet and an air outlet comprising an outlet conduit; an air flow path extending from a dirty air inlet to a clean air outlet and including a suction motor and the air treatment member; a pre-motor filter positioned in the air flow path downstream from the outlet conduit; and, an agitation member operatively engageable with the pre-motor filter.

Abstract: A vibrating air filter of a robotic vacuum comprising an electromagnet, a permanent magnet and an air filter. The electromagnet may comprise a metal wire and a power source connected to a first end of the wire. The power source may deliver electric pulses in alternating directions through the wire creating an electromagnet. The metal wire may be coiled around or placed adjacent to the permanent magnet and a second end of the wire may be connected to an air filter. Interaction between the magnetic fields of the electromagnet and permanent magnet may cause vibration of the wire and hence connected filter. Vibration of the filter may loosen any dust and debris latched onto the filter that may be shed into a dust bin of the vacuum.

Abstract: A dust containment manifold includes an angled, broadened head with one or more openings through which suction is applied to bullets as they fall from a deceleration chamber or bullet trap. The dust containment manifold may be disposed generally beneath the bullet trap and angled so as to reduce the chance that small fragments will enter the bullet trap ventilation system and become lodged in the ventilation filters.

Abstract: The present invention generally relates to a process and apparatus for cleaning and removing particulate deposits in a particulate filter, in particular for the dry removal of ash deposits with a diesel particulate filter. Compared to the art known procedures, the method of the present invention is based on the provision of a two-stage process including a stage wherein the filter is exposed to a structural resonant frequency under pressure and a stage wherein the filter is exposed to a reverse flow. Combination of a structural resonance frequency with a reverse flow results in an efficient two-stage removal of the debris from the filter without causing any damage to the ceramic body of the filter.

Abstract: Industrial vacuum systems are disclosed, as are filter chambers for industrial vacuum systems and other filtration applications. The filter chambers in these systems use two distinct types of filtering elements within a single chamber, arranging the filter elements such that air cannot pass through a secondary filter element until the air has first passed through and been filtered by a number of primary filter elements. The airflow within the filter chamber may be essentially vertical, and the secondary filter element may be positioned above the primary filter elements. The filter chamber may also include an agitation system for cleaning the filtering elements. The agitation system may be constructed such that it can operate while the system is in use.

Abstract: A gas flow control device and a filtering system for a flow of dust-laden gas. The gas flow control device includes a damper blade arranged to be pivoted through a definite pivoting angle around a substantially horizontal pivot axis, for regulating the flow of the dust-laden gas in an inlet channel by pivoting the damper blade between an open position and a closed position. At least one substantially planar guide baffle is attached to each of two opposite, substantially planar surfaces of the damper blade, the at least one guide baffle extending from the pivot axis in the direction of the normal of the general plane of the damper blade substantially to an opposite inner surface of the inlet channel, for controlling the distribution of the dust-laden gas flow to a fabric filter enclosure.

Abstract: A general ventilation and air filtration system includes an air filtration control unit that monitors and controls an air flow through an air filter and maintains the air flow at a target velocity set point. The target velocity set point is maintained by monitoring and regulating the power of a motor powering a blower that generates an air flow though the air filtration system and through the air filter. By regulating the air flow and maintaining it in the target set point, power consumption and air filter life are significantly improved.

Abstract: A general ventilation and air filtration system includes an air filtration control unit that monitors and controls an air flow through an air filter and maintains the air flow at a target velocity set point. The target velocity set point is maintained by monitoring and regulating the power of a motor powering a blower that generates an air flow through the air filtration system and through the air filter. By regulating the air flow and maintaining it in the target set point, power consumption and air filter life are significantly improved.

Abstract: Industrial vacuum systems are disclosed, as are filter chambers for industrial vacuum systems and other filtration applications. The filter chambers in these systems use two distinct types of filtering elements within a single chamber, arranging the filter elements such that air cannot pass through a secondary filter element until the air has first passed through and been filtered by a number of primary filter elements. The airflow within the filter chamber may be essentially vertical, and the secondary filter element may be positioned above the primary filter elements. The filter chamber may also include an agitation system for cleaning the filtering elements. The agitation system may be constructed such that it can operate while the system is in use.

Abstract: In a process for removing entrained particulates from a gas, a chemical reaction may be conducted in a vessel. Conducting the chemical reaction may include suspending particulates in a gas in a fluidized bed in the vessel. A portion of the gas and entrained particulates may be directed to a filter medium and the entrained particulates may be filtered from the gas. Filtering the entrained particulates may include directing the gas from a feed side of the filter medium through the filter medium to a filtrate side of the filter medium and may also include directing at least a portion of the entrained particulates generally tangentially along the feed side of the filter medium to scour the feed side of the filter medium. The particulates may then be directed from the feed side of the filter medium into a dip leg.

Abstract: The present invention pertains to a device for cleaning gases containing particles with a bellows and with at least one filter element arranged in the bellows. To ensure effective filtration without limitation of the mobility of the bellows, the present invention provides for at least one filter element to be fixed at a bellows inner flange of a bellows corrugation in a positive-locking manner.

Abstract: A dust collector having a filter for catching dust in air flowing in an intake path is provided. A pair of the intake paths are formed so as to be combined together on an upstream side of an electric blower provided in a main body. A pair of communication paths allow a discharge passage to communicate with each of the intake paths. A first opening and closing member is provided so as to open and close the intake path, and in a normal state, is biased to open the intake path. A second opening and closing member is provided so as to open and close the communication path, and in the normal state, is biased to close the communication path, and opens the communication path in response to a closing operation of the intake path by the first opening and closing member.

Abstract: A gas distributor for a granular moving-bed filter comprises a distribution module, arranged inside a granular moving-bed filter. The distribution module comprises at least one flow-distributing curtain to be used for allowing a turbulent gas flow with dust mixed therein to flow therethrough, resulting that before the turbulent gas flow enters the granular moving-bed filter, the turbulent gas flow is transformed into a more uniformly distributed gas flow and the dust contained therein are partially filtered out.

Abstract: A vacuum loader system is disclosed. In the vacuum loader system, the air inlet comprises a load-bearing member of a support structure that supports the system. The vacuum loader system also includes a filter chamber with co-located primary and secondary or safety filter elements. A safety filter element is at the center of the filter chamber, surrounded by primary filter elements. After the air flows through the primary and safety filter elements, it is directed downwardly, out of the filter chamber and back toward the blower, beyond which it is ultimately expelled through a silenced outlet. In some embodiments, the conduit that carries air from the filter chamber toward the blower may also be a member of the support structure.

Abstract: A filter device disposed in a moist fluid passage of the fuel cell system includes a fluid introducing path which introduces a fluid that flows in the moist fluid passage, a filter to permeate the fluid introduced from the fluid introducing path and remove foreign matter in the fluid, a fluid discharge path which discharges a fluid that passed the filter, and a rotating driving mechanism, connected with the filter, that rotates the filter so that substances that adheres to the filter are removed by the centrifugal force. In the filter device, water does not adhere to and does not remain in the filter. When leaving the system under the low temperature after the system stops, blockage by freezing the filter can surely be prevented. The complex control and the heat source such as a heater for defrost is unnecessary. Thus, a cheap and compact filter device can be provided.

Abstract: A filter system for an explosion-proof enclosure is described herein. The filter system can include a pre-filter assembly located outside the explosion-proof enclosure. The pre-filter assembly can include a pre-filter material configured to control air passing therethrough. The filter system can also include a filter assembly coupled to the pre-filter assembly. The filter assembly can further control the air received from the pre-filter assembly and passing therethrough into the explosion-proof enclosure.

Abstract: A filter device disposed in a moist fluid passage of the fuel cell system includes a fluid introducing path which introduces a fluid that flows in the moist fluid passage, a filter to permeate the fluid introduced from the fluid introducing path and remove foreign matter in the fluid, a fluid discharge path which discharges a fluid that passed the filter, and a rotating driving mechanism, connected with the filter, that rotates the filter so that substances that adheres to the filter are removed by the centrifugal force. In the filter device, water does not adhere to and does not remain in the filter. When leaving the system under the low temperature after the system stops, blockage by freezing the filter can surely be prevented. The complex control and the heat source such as a heater for defrost is unnecessary. Thus, a cheap and compact filter device can be provided.

Abstract: A dust filter for filtering dust out of an air stream has a filter membrane pleated into a row of pleats. A pleat deflector is movably suspended for moving along the row of pleats for cleaning the filter membrane. The deflector has a free end extending between the pleats when the deflector and the pleats are in undeflected condition, such that when the deflector is moved along the row of pleats, the pleats are deflected and released in succession along the row. The deflector includes a flexible plate of which at least a portion between the suspension and the free end has a width transverse to the direction of movement of the deflector, where the width decreases with the distance to the suspension.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: The invention is a separator designed to separate an incoming stream of liquid, gas, and some particulate matter into a separate gas stream, and a separate liquid stream containing the particulate matter. This is achieved through cyclonic action and the use of a float to operate internal valves within the cyclone. The float is mounted on a shaft which is rotated by the motion of the incoming fluid stream and this motion is used to agitate the solids in the liquid so as to prevent the outlet port from becoming jammed. The outlet port also has an auger contained therein that removes particulate matter.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: In accordance with one embodiment, a filter assembly includes a housing having an inlet for particulate laden gas and an outlet for clean gas. The assembly also has at least one filter being capable of filtering particulate from the gas that is located in the gas flow between the inlet and outlet. The filter assembly further includes a cleaning mechanism for removing particulate from the filter and the filter assembly.

Abstract: A mobile surface maintenance machine with a debris hopper and a filter module providing at least two filter stages for separating dust and debris within the debris hopper, the filter module including a filter shaking mechanism and a housing adapted to seal against the upper opening of the debris hopper, and wherein the debris hopper is removed from air communication with the exhaust fan when the debris hopper is in a debris dump configuration and is returned to air communication with the exhaust fan when the debris hopper is lowered into an operational configuration.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: Embodiments describe an arrangement for reducing the amount of LPA that reaches a NOx reducing apparatus such as a SCR system. The arrangement includes deflection elements, screens, means for dislodging any LPA that might become lodged in the screens, an aperture for removing the ash through, hoppers or collection means and an ash conveyance system. The arrangement is positioned in a region of ductwork with a reduced gas flow such as the SCR reactor. The screens are positioned relative to one another to direct the LPA downward toward an aperture for removal. In one embodiment the positioning of the screens creates a half-trough or inverted pyramid appearance when placed next to a vertical wall in the flue gas ductwork or the SCR reactor. The low point of the trough is in communication with the aperture allowing the LPA to exit the flue ductwork.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: The present invention relates to a method and a system for treating polluted gases prior to their emission into the atmosphere. The system comprises a treatment chamber having an inlet for receiving polluted gas and an outlet for expelling treated gas, the treatment chamber including at least one treatment cell having a filtering layer for treating the polluted gas when the polluted gas comes in contact with the filtering layer. The system also contains a powder container connected to the treatment chamber such that air laden with the powder can flow to the treatment chamber to form a filtering layer on the at least one treatment cell. The system contains an air flow generator connected to the outlet of the treatment chamber and to the container which is connected to the treatment chamber, for causing air flow to the container, to the treatment chamber and in the environment.

Abstract: A system includes a resonant frequency modeler for determining a resonant frequency of a node on a collecting plate that collects particles from a gas flow; and a wave generating device that applies a wave having an applied frequency substantially equal to the resonant frequency to the node of the collecting plate to remove particles from the collecting plate. An electrostatic precipitator (ESP) including the system and related method are also provided.

Abstract: A filter device disposed in a moist fluid passage of the fuel cell system includes a fluid introducing path which introduces a fluid that flows in the moist fluid passage, a filter to permeate the fluid introduced from the fluid introducing path and remove foreign matter in the fluid, a fluid discharge path which discharges a fluid that passed the filter, and a rotating driving mechanism, connected with the filter, that rotates the filter so that substances that adheres to the filter are removed by the centrifugal force. In the filter device, water does not adhere to and does not remain in the filter. When leaving the system under the low temperature after the system stops, blockage by freezing the filter can surely be prevented. The complex control and the heat source such as a heater for defrost is unnecessary. Thus, a cheap and compact filter device can be provided.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: An apparatus for cleaning an air filter includes a body, a closed chamber formed within the body, a fluid dispersing member having a portion thereof mounted for rotation within the body and passing through the chamber, a plurality of orifices formed through the wall of the fluid dispersing member and an arrangement for rotating the fluid dispersing member. The arrangement either includes a combination of nozzles secured to the fluid dispersing member and positioned within the chamber and an irregular inner wall surface of the chamber capable of providing resistance to a fluid flow discharged into the chamber or fins disposed on the fluid dispersing member and a passageway through the body for directing fluid under pressure onto the fins. Fluid supplied under pressure to the fluid dispersing member exits through the plurality of orifices toward an inner surface of a air filter filtering medium causing contaminants to exit therefrom.

Abstract: A dust collector includes a centrifugal separator, a discharge unit having a filtered dust collecting space provided with a discharge unit discharge hole at a discharging side of the centrifugal separator and an intake passage communicating with a bottom of the discharge unit discharge hole, a filter unit provided with a filter member and mounted at the discharge unit discharge hole, and a sealing member including a dust removing device mounted on the filter unit and a dust container formed on a bottom surface of the centrifugal separator, wherein the sealing member opens the filtered dust collecting space and the intake passage by means of the weight thereof and closes the filtered dust collecting space and the intake passage by means of negative pressure.

Abstract: A cyclonic chamber for use in air filtration devices. The chamber includes an apex opposite a base with sidewalls extending therebetween. The cyclonic chamber is preferably parabolic in cross-section or tubular with a hemi-spherical cap. The base contains an outflow passage and a conical filter extending therefrom. An inflow passage is provided proximate the apex. The inflow and outflow passages are parallel but not aligned. The chamber interior is smooth. The smooth interior and offset relationship of the inflow and outflow passages causes air to take a cyclonic path between the inflow passage and the filter. Debris in the airstream is pushed outward—away from the filter—by centripetal force. Eddies form proximate the base. Debris escapes the airstream there, where it either remains or, depending upon the chamber's orientation relative to gravity, falls back into the airflow where it is again directed away from the filter.

Abstract: A filtering device filters out impurities contained in an air stream, and includes an inner filter plate, an outer frame that houses said filter plate thereinside, a structure for retaining said filter plate and conveying the shaking motion, a support socle applied on to said structure, a rotary electric motor, whose rotor is provided with one or more unbalanced masses, and which is fixedly mounted on said socle. The electric motor is operated in an intermittent manner, preferably with a direct-current, substantially square-wave supply voltage according to an ON-OFF cycling pattern, so as to generate a very broad spectrum of shaking frequencies that proves more effective in enabling impurities to be removed from the filter plate.

Abstract: A filter element has a reinforcement band or ring along at least a portion of the perimeter thereof and performing a support function thereat preventing or minimizing damage upon attempted percussive cleaning of the filter element by service personnel striking the perimeter against an impact surface. Alternatively, a failure band or ring is provided along at least a portion of the perimeter and performs a designated failure function to a failure condition thereat upon attempted percussive cleaning, with the failure condition providing at least one of: a) an indication to service personnel that the filter element has been damaged and should not be re-installed; and b) a deformed condition preventing re-installation.

Abstract: One embodiment described herein relates to a system for removing pollutants from a flue gas. The system includes a selective catalytic reduction (SCR) system having a SCR reactor containing a NOx reducing catalyst and one or more SCR protective devices. At least one of the SCR protective devices is connected to a rapping hammer system that actively remove fly ash collected on the SCR protective devices.