Abstract: An apparatus having: a vacuum chamber for enclosing an article support, the article support configured to support an article such that a volume is defined between the article support and the article, the article support including a plurality of supporting protrusions configured to provide a plane of support for the article; a conduit for providing a fluid to the volume such that the fluid provides heat transfer between the article and the article support; and a controller for controlling the fluid supply to the volume, wherein the controller is configured to control a fluid supply unit to start removing the fluid substantially at a time the article reaches a stable temperature.

Abstract: A surge protection device with stack spark gaps, whereby a stack spark gap is formed from multiple electrodes and insulating elements that are arranged between the electrodes, with an ignition switch for influencing the ignition behavior of the stack spark gaps, with a first electrically conductive clamping element and with a second electrically conductive clamping element, whereby the clamping elements are arranged on opposite sides of the stack spark gaps, with at least one connecting element by which the clamping elements are connected to one another, and with connection elements for electrical connection of the stack spark gaps.

Abstract: The object of the invention is an ignition circuit for a series connection of at least two spark gaps for limiting overvoltages with medium and high power, particularly overvoltages corresponding to pulse shapes 8/20 ?s and 10/350 ?s with amplitudes of about 10 kA to about 200 kA (class I arrester). The spark gaps are each equipped with at least one auxiliary electrode. The ignition circuit has a first varistor and a second varistor, with the ignition circuit being particularly suited to limiting overvoltages with medium power, particularly overvoltages corresponding to pulse shape 8/20 ?s with amplitudes of about 10 to about 100 kA (class II arrester). The ignition circuit is designed to be connected to the auxiliary electrodes, with the ignition circuit Z having two ignition subcircuits. The first ignition subcircuit TZ1 has the first varistor VAR1 and is designed to ignite the first spark gap. The second ignition subcircuit has the second varistor and is designed to ignite the second spark gap.

Abstract: An electrode configuration for an electrical component, in particular a surge protector, includes two electrodes extending in a plate-shaped manner parallel to a radial plane relative to a connection axis of the electrodes, defining an axial direction. At least one electrode has a connection region lying in the radial plane and at least two, three or four ribbon-shaped strips each extending away from the connection region and at least partially in circumferential direction relative to the axial direction. A fault arc, occurring during a lightning strike, can be conducted outwards away from the electrical component and forced into rotation around the electrical component in an effective manner due to the ribbon-shaped strips at the outer edge of the connection region and at least two ribbon-shaped strips overlapping each other at a spacing with respect to their delimiting surfaces lying perpendicular to the axial direction.

Abstract: An adapter assembly includes an adapter body and a connector. The adapter body has a main leg and a cross leg. The main leg and cross leg have intersecting passages. The connector includes: an electrically conductive semi-flexible joint having first and second opposed joint ends; a first end portion on the first joint end, with the first end portion including a body configured to mechanically and electrically couple with an electrical conductor; and a second end portion on the second joint end, with the second end portion including a head configured to directly or indirectly electrically connect the semi-flexible joint to a termination of electrical equipment. The head is disposed in the cross leg passage and the semi-flexible joint is disposed in the main leg passage. The semi-flexible joint is configured to enable limited movement of the head relative to the cross leg passage.

Abstract: Method and device for monitoring the status of a sheath voltage arrester of a cable system, a verification signal being supplied to a measuring loop which comprises the sheath voltage arrester and a measurement signal which is subsequently produced in accordance with the frequency-dependent impedance of the sheath voltage arrester being measured at the measuring loop in order to establish the status of the sheath voltage arrester by evaluating the measurement signal.

Abstract: A method of converting atmospheric electrical discharge to a useable form of energy by arresting, storage and retransmission of lightning induced electrical discharge is disclosed. The invention discloses methods of deploying this technology even in isolated locations where no electricity infrastructure exists. Additionally, the potential for achieving in excess of 1 GWe of electrical power supply at costs orders of magnitude lower than fossil fuel or solar is also disclosed. Isolated collection units are disclosed. A method of deployment of these devices on individual cars and recharge stations is disclosed which in effect unplugs these automotive and recharge stations from the grid. This capability significantly decreases their dependence on the electricity grid infrastructure, enabling a much more enhanced rollout capability for the industry. The concept of Energy Dams is disclosed.

Abstract: An apparatus for providing electrostatic discharge protection includes a plurality of conductive circumferential extensions defined by overlapping circular voids between a first conductor surface and a second conductor surface.

Abstract: In order to make it possible to direct sufficient microwave energy at a target with an electronic device which is to be interfered with or to be destroyed, the beams (7) from at least two antenna arrays (10) are focused on an effective area (8) in the vicinity of that target, preferably from a vehicle (3) which is equipped with these arrays (10). For effective super-imposition of the emitted microwave energy (7) in the emission direction of in each case one of the arrays (10), the use of an arc for discharging the capacitance (43) of the resonator via its spark gap (13) is observed, and is recorded quasi-continuously optoelectronically. The electrode separation of the spark gap (13) or the fluid pressure of the dielectric in the vicinity of the spark gap (13) is then varied by control elements such that all of the spark gaps (13) in an array (10) ignite virtually at the same time, so that their discharge current pulses which lead to the emission of the microwave energy (7) start virtually in phase.

Abstract: An overvoltage protection element for discharging transient overvoltages with at least two electrodes, with at least one ignition element of insulating material located between the electrodes, and with an air breakdown spark gap which acts between the electrodes, when the air breakdown spark gap is ignited an arc being formed between the two electrodes. An overvoltage protection element is provided with an ignition element which can be produced especially easily, the ignition element being made and arranged such that, between the two electrodes, there is an area of weakened insulation (ignition area) and when there is a voltage on the ignition element, a discharge on the surface of the ignition element leads to a conductive connection between the two electrodes, the conductive connection having a low current carrying capacity.

Abstract: A device for protection against voltage surges, comprising: a first spark gap (E1); a first pre-triggering system (2), electrically connected to the first spark gap (E1), so as to enable its being primed; a control device (4) electrically connected to the first pre-triggering system (2) so as to activate same. The invention is characterized in that it comprises at least a second spark gap (E2) mounted parallel to the first spark gap (E1), and electrically connected to a second pre-triggering system (3), such that the control device simultaneously activates the first and the second pre-triggering systems (2, 3), so as to trigger simultaneously the first and second spark gaps (E1, E2). The invention also concerns devices against voltage surges.

Abstract: An overvoltage device that is formed from a MOV device that is coupled in parallel with a spark gap. This device is coupled upstream from electronic components to protect these components from damage. For example, in one embodiment, the overvoltage device is coupled to a fault circuit interrupter such as a GFCI, across the phase and neutral lines to protect components of the GFCI from an overvoltage condition. In one embodiment the overvoltage device is formed as an MOV physically coupled to a spark gap wherein the MOV and the spark gap are electrically coupled across the phase line and the neutral line in parallel.

Abstract: The present invention provides an arrester in which energy during discharge is not concentrated in one point and which has good responsiveness to overvoltage. The arrester is provided with an energy absorber 3 that absorbs energy when a lightning strike occurs, and a pair of conductive electrodes 1 and 2. Between the pair of conductive electrodes 1 and 2, two air gaps 9 are formed in series, between the conductive electrode 1 and the energy absorber 3, and between the conductive electrode 2 and the energy absorber 3. The two air gaps 9 include planer gaps.

Abstract: An apparatus for providing electrostatic discharge protection includes a plurality of conductive circumferential extensions defined by overlapping circular voids between a first conductor surface and a second conductor surface.

Abstract: An apparatus for providing electrostatic discharge protection includes a first conductive trace and a second conductive trace. The first conductive trace defines a first conductive periphery and is deposited on a first surface. The second conductive trace defines a second conductive periphery and is deposited on a second surface. The second surface is spaced apart from the first surface by a gap distance and in parallel relation so that a spark gap is defined by the gap distance between the first conductive periphery and the second conductive periphery.

Abstract: The superimposition of the microwave fields of an array (10) of microwave generators (11), with self-firing spark gaps (13) for the discharge of storage devices (43), which are charged up to a high voltage, results in an increase in field strength and a capacity for influencing the frequency spectrum of the emitted high-energy high-frequency field and the emission direction thereof.

Abstract: The invention relates to a surge absorber provided with; a surge absorber element composed of a columnar non-conductive member and a conductive film formed dividedly via a discharge gap on a peripheral surface of the non-conductive member, a pair of sealing electrodes disposed at opposite ends of the surge absorber element and touching the conductive film, and a glass tube with opposite ends closed by the sealing electrodes, and the surge absorber element and an inert gas encapsulated thereinside. In the surge absorber of the invention, a face of each sealing electrode which contacts with the surge absorber element is formed in a concave shape symmetrical with a central axis of the glass tube. As a result the surge absorber element can be positioned in the center of the glass tube with high accuracy, the life span and the surge current capacity of the surge absorber can be improved, and low cost and small size becomes possible.

Abstract: The component with fault arc protection has an insulator in the form of a pillar, a first electrical conductor system which is provided on the insulator head and can be connected to high-voltage potential, and a second electrical conductor system which is provided on the insulator foot and can be connected to a ground potential. Each of the two electrical conductor systems contains an arcing electrode (7) for dissipating any fault arc which occurs in the event of a discharge between the two electrical conductor systems. The fault arc is dissipated particularly effectively if at least one of the two arcing electrodes (7) is in the form of a cup and has a cup base (12), which is attached to one electrical connection of the first or of the second electrical conductor system, as well as a cup wall (13) which is adjacent to the cup base (12) and extends predominantly in the direction of the axis (2) of the pillar.

Abstract: Electrostatic wafer chucks are disclosed for use in holding a substrate (e.g., semiconductor wafer) during processing of the substrate in a vacuum chamber or other reduced-pressure environment. A representative wafer chuck provides improved control of the vacuum level in the vacuum environment while providing a mechanism (lift pins) for raising and lowering the substrate relative to the chuck. The chuck body defines a wafer-mounting surface that contacts the under-surface of the substrate. The chuck body defines a gap between the under-surface of the substrate and the chuck for conducting a heat-transfer gas, and multiple feed-through holes extending through the chuck body. Surrounding each feed-through hole is at least a first protrusion configured to separate the respective feed-through hole from the gap. A respective lift pin in each feed-through hole extends from the chuck body across the gap to the under-surface of the substrate.

Abstract: A device for containing an electrical discharge arc and holding the arc substantially captive until it is extinguished. The device comprises two spaced apart conductor systems (13 and 14) that are connected to points (23 and 24) of different voltage potential in an electrical circuit, so that arc current will flow through and between the conductor systems (13 and 14) in the event of an arc discharge between the conductor systems. The conductor systems are arranged normally to locate about an insulated portion (22) of an electrical apparatus.

Abstract: A surge arrester which includes a pair of spaced metal electrodes and a semiconductor element interposed between the metal electrodes and in contact with at least one of the metal electrodes. The semiconductor element functions at least partially to bridge a gap between the metal electrodes with such gap serving as a current path between the metal electrodes in the event a voltage applied across the metal electrodes exceeds a firing voltage of the surge arrester. The semiconductor element includes a metal coating on at least a substantial portion of its outer surface which is in contact with the at least one metal electrode. The coating includes a gap between the electrodes and the gap may include a notch in the gap.

Abstract: An improved surge arrester includes metal oxide varistors in series with spark gap assemblies arranged such that the MOV elements conduct the low magnitude, steady-state current through the arrester along a path that is separate and distinct from the path through which impulse current is conducted during an overvoltage.

Abstract: A discharge relay electrode is located between terminal electrodes of a gap-type surge absorber. In a microgap embodiment of the invention, a conducting film on a surface of an insulating tube is split by two circumferential gaps spaced apart longitudinally. The discharge relay electrode is positioned between the two gaps. In a gap type surge absorber, the discharge relay electrode is positioned within the insulating tube midway between the end electrodes, substantially filling the cross section of the tube, and dividing the interior of the tube into a plurality of chambers. For both types of surge absorbers, the discharge relay electrode is effective to relay discharge between the terminal electrodes.

Abstract: A non-linear resistor having a high impulse withstanding ability is obtained by directly applying a crystallized glass to the side surface of a sintered body of a ZnO element, and then bake-attaching the crystallized glass to the side surface of the ZnO element by heat treatment. Since the impulse withstanding ability is improved by applying the crystallized glass as the side surface high-resistivity layer of the voltage non-linear resistor, the performance and reliability of an arrester including the resistor is improved.

Abstract: An object of the present invention is to provide a thyristor valve arrester capable of measuring leakage currents of arrester elements in a simple construction and a DC power transmission thyristor valve having it used therein.A multiple of laminated arrester sets are arranged in parallel with a multiple of thyristor valves. Each arrester set is made of a plurality of arrester units arranged in parallel. Each adjoining arrester sets has through an insulator an inter-stage connecting conductor therebetween at a position corresponding to the respective thyristor valve terminals. An end of each arrester set and the respective inter-stage connecting conductors have a leakage current ammeter and a surge counter connected therebetween in electrical parallel. Each inter-stage connecting conductor and the respective thyristor valve stage are connected together by a thyristor valve connecting conductor.

Abstract: A three-terminal surge arrestor unit employs air gaps augmented with semiconductors to protect a circuit having two ungrounded conductors. Conductive electrodes and the semiconductors are mounted on a common axis in a sandwich arrangement and secured in fixed relative positions. Two air gap lightning arrestors provide current paths for the respective conductors to ground in response to lightning strikes or other damaging surges, and an equalizer is incorporated in the electrode configuration to establish a current path between the conductors to protect them from an excessive voltage differential. The resulting configuration is a single, three-terminal unit designed to replace multiple unit air gap systems and gas tube arrestors.

Abstract: An overvoltage protective device for a series capacitor (C) has a main spark gap and a first auxilary spark gap, arranged adjacent thereto, for ignition of the main spark gap. A second auxiliary spark gap is arranged in association with the first auxiliary gap for ignition thereof. The first and second auxiliary spark gaps are connected between one of the electrodes of the the main spark gap and a voltage divider which comprises resistors (R1, R2, R3 ) and a varisistor (VR1) . When the knee voltage of the varisistor is exceeded, the second auxiliary spark gap is ignited, the arc of which initiates ignition of the first auxiliary spark gap, the arc of which in turn moves towards and ignites the main spark gap. During the arcing time of the spark gap, a controlled discharge of the series capacitor through a resistor (R2) takes place.

Abstract: An electrical assembly, such as an insulator or a surge arrester, utilizing a pair of end collars for coupling an elastomeric weathershed housing to a pair of metallic end fittings, and for reducing electrical stress at the interface of the ends of the weathershed housing and the end fittings, and for sealing the ends of the weathershed housing to the end fittings. In particular, a radially directed force is applied to the weathershed housing by insertion of the core member into the axial bore of the weathershed housing causing radial outward expansion of the weathershed housing into intimate contact with the end collars. Also, each of the ends of the weathershed housing is held in contact against the inner end of the respective end fitting to seal the interface therebetween. Accordingly, a watertight seal is created at the interface between each of the end fittings and the ends of the weathershed housings.

Abstract: An excellent voltage non-linear resistor for use in a gapped lightning arrestor having a composition containing 1 0.5-1.2 mole % of bismuth oxide calculated as Bi.sub.2 O.sub.3, 2 0.3-1.5 mole % of cobalt oxide calculated as Co.sub.2 O.sub.3, 3 0.2-0.8 mole % of manganese oxide calculated as MnO.sub.2, 4 0.5-1.5 mole % of antimony oxide calculated as Sb.sub.2 O.sub.3, 5 0.1-1.5 mole % of chromium oxide calculated as Cr.sub.2 O.sub.3, 6 0.6-2.0 mole % of silicon oxide calculated as SiO.sub.2, 7 0.8-2.5 mole % of nickel oxide calculated as NiO, 8 0.004-0.04 mole % of aluminum oxide calculated as Al.sub.2 O.sub.3, 0.0001-0.05 mole % of boron oxide calculated as B.sub.2 O.sub.3 , 10.circle. 0.001-0.05 mole % of silver oxide calculated as Ag.sub.2 O, and 11.circle. the rest of zinc oxide, 12.circle. a limited current of 250-350 V/mm at a current density of 0.1 A/cm.sup.2 calculated per unit thickness of the sintered resistor, 13.circle. a limited current ratio of V.sub.0.1A /V.sub.0.1mA of 1.2-1.

Abstract: A surge arrester comprises a plurality of cylindrical arrester elements (11) of metal oxide varistor material which are arranged, with confronting end surfaces, between two end electrodes (13) in an elongated protective housing (10) which is resistant to deformation under the operating conditions for the surge arrester. The housing is of cross-linked HD polyethylene and is shrunk onto the envelope surfaces of the arrester elements and onto envelope surfaces on heat-absorbing metallic bodies (12) arranged between the arrester elements.

Abstract: A trigger circuit for a spark gap chain with at least two series-connected spark gaps, of which at least one is provided with at least one trigger electrode, includes a resistor chain which is connected in parallel with the spark gap chain and comprises at least two series-connected resistor groups. That of the resistor groups which is connected in parallel with the spark gap provided with a trigger electrode comprises a voltage-dependent resistor, built up of zinc oxide varistors, which is connected in series with a linear resistor. The voltage across the linear resistor is supplied to the trigger electrode of the spark gap for ignition of the spark gap when this voltage amounts to a pre-determined value. The spark gaps are primarily intended to be utilized for overvoltage protection of series capacitors.

Abstract: For switching high voltages, high frequencies and at high numbers of switching actuations, a gas discharge structure is provided which is composed of a series circuit of two or more individual arresters which comprise electrodes of copper and which are filled with gas which is at least partially composed of hydrogen. The gas discharge path is suitable for switching frequencies in the kHz range.

Abstract: A protector module (30) for protecting the conductors of a telephone loop cludes a pair of protector assemblies (40-40') which are supported within a common housing (32). A gas tube voltage protection subassembly (42) of each protector assembly is connected electrically to a grounding subassembly (44) for causing current associated with excessive voltage surges to be conducted to ground. A first electrode includes a portion which extends through annular dielectric and metallic members and an opening of an open-ended metallic container (93) to engage a shunting element (62) of a current protection subassembly (41). The superimposed annular members are held in engagement with the first electrode at a substantially constant pressure by axial forces applied by turned-in portions (109--109) of a side wall of the metallic container. The shunting element is supported at one end of the line pin in an initial position by a fusible material.

Abstract: A mains electrical plug incorporates a zinc oxide non-linear resistor device (10) in the form of a circular zinc oxide disc having three electrode portions (2) provided on one face and contacting the earth, neutral and live pins (5) of the plug and a single electrode (3) on its other face, the device (10) thereby providing surge protection to the three electrical circuits provided within the plug.

Abstract: An overvoltage arrester having power connectors at its opposite ends is provided with an insulating housing that encloses a stack of coaxially arranged cylindrical varistors at least partially embedded in insulating material. An annular space is provided between the insulating material and the interior wall of the housing and is filled with an electrically insulating, heat-conducting material. The housing is protected from bursting in the event of the occurrence of an electrical flash-over along the varistor stack by a pressure relief duct that extends along the varistors between the power connections.

Abstract: A lightning arrester of the station class is equipped with a ceramic housing protective heat shield liner formed of an ablative material capable of giving off a gas when subjected to a fault current arc. The evolved gas contributes to a rapid internal pressure buildup calculated to rupture housing end sealing diaphragms and quickly vent the arrester housing interior to prevent housing fracture. The arrester end structures are provided with expansive radial vents to accommodate unimpeded internal pressure relief.

Abstract: A surge voltage arrester, with a column of arrester elements arranged in a housing and several shielding bodies enclosing the column, includes voltage controlling elements arranged between the shielding bodies. The size and type of fastening of the voltage controlling elements can correspond to that of the support bodies which are likewise arranged between the shielding bodies. Through a distribution of the voltage controlling elements over the length of the surge voltage arrester, a uniform voltage distribution can be achieved if the arrester is installed in a grounded metal housing.

Abstract: A surge arrester including an outer elongated housing and an inner liner is disclosed herein. The outer housing is constructed of a material which will not break as a result of internal electrical arcing, specifically a relatively resilient, electrically insulating and non-tracking material which in a preferred embodiment is EPDM rubber. In order to add structural integrity to the arrester, its inner liner is constructed of a high strength material, preferably resin impregnated fiberglass.

Abstract: Disclosed is an overvoltage arrester in which the active part comprises a number of shielding elements with arrester elements fastened thereto in the interior thereof. The shielding elements along the inner circumference thereof have a circular depression for electrically and mechanically connecting the arrester elements to the shielding elements. The shielding elements are connected to each other by insulating support members and conducting support members. The arrester elements can be arranged in a star- or cross-shaped structure at the center of which conducting or insulating connecting members may be provided. Arresters according to the invention are particularly suited for use in pressurized gas-insulated metal-encapsulated high-voltage switching installations in conjunction with arrester elements having voltage-dependent resistors of the zinc oxide type. The active part of the arresters according to the invention can be installed outdoors without a housing.

Abstract: Coaxial conductors are protected against electrical overvoltage by at least one element of non-electroded varistor material that adjoins each other varistor element and conductor with which it contacts. With this construction, overvoltage current initiated through the varistor material arcs at the point contacts between varistor elements and, as the current increases, the arcs increase until they become a continuous arc between conductors, bypassing the varistor material.

Abstract: A gapless arrestor assembly for a high voltage bushing including an insulating elastomeric housing having a bore formed in one portion thereof and a receptacle formed in another portion thereof and a surge arrester assembly positioned in the bore in said housing, the arrester assembly being formed from one or more surge arrester blocks and including a connector element at the inner end of the arrester blocks, the connector element being movably connected to the surge arrester blocks and a probe contact positioned in the receptacle and rigidly connected to the connector element, the connector element allowing movement of the probe contact independent of the arrester blocks.

Abstract: A secondary valve arrester for protection of secondary electrical systems, comprises a housing having a lid and base portion, the latter of which includes a plurality of compartments each of which is dimensioned to receive a valve block and spark gap assembly or a varistor assembly; the number of said assemblies included in the arrester corresponding to the number of phases protected in the system. Each said assembly includes connecting electrodes of similar construction, each connecting electrode having two offset male terminals and one offset female terminal for connection to externally connected lead wires or other connecting electrodes. The housing lid includes first and second rib sets for extension into the base portion to retain the said assemblies in a tightly stacked condition in respective compartments.

Abstract: Surge voltage arresters are provided with a frangible housing to cause the housing to break at a predetermined section into a relatively few pieces upon varistor failure. The breaking of the housing deters excessive pressure buildup within the arrester.

Abstract: An overvoltage arrester wherein the arrester comprises an insulating housing which encloses a body of cast resin in which is embedded a voltage dependent resistor and a first connecting device, a portion of which protrudes from the resin body and extends out of the housing. The arrester is further provided with a spark gap formed as a separate unit and a second connecting device anchored to the spark gap, both of the latter elements also being disposed in the housing.

Abstract: A compact voltage surge arrester employs a miniature series gap electrode arrangement in series with a plurality of zinc oxide varistors. The series gap arrangement provides the use of zinc oxide varistors without auxiliary heat sinks.

Abstract: Arresters for protecting electrical equipment from damage or destruction due to overvoltage surges, for example overvoltage surges caused by lightning strokes, are provided that are fabricated or assembled integrally with cable taps, cable joints, separable insulated connector apparatus, and overhead arrester assemblies. Arresters are also provided for insertion in arrester receptacles which are integrally provided with cable taps, joints, separable insulated connector apparatus or cable receptacle devices. The arresters include a laminated enclosure for excluding the atmosphere, air and moisture, along the outer surfaces of arrester components and along the outer surface of an insulating housing layer, as well as along interfaces with insulated power cable and separable insulated arrester components. The housing is either fabricated by coating or molding onto the arrester components or by inserting the arrester components in an interference fit relationship into a premolded elastomeric enclosure.

Abstract: A surge diverter connected between a conductor and ground comprising several spark-quenching gaps, voltage-controlled shunting resistors connected in series with these gaps and voltage controlled control-resistors, each connected in parallel either to a gap alone or to a unit formed by a gap and a shunting resistor in series with the latter. The voltage-controlled control-resistors have current-voltage characteristics with substantially the same steepness, while the resistance value of these control-resistors at the rated voltage increases sequentially from the conductor to grand.

Abstract: Surge arrester spark gap assemblies for use within surge voltage arrester devices employ the gap electrode structure to direct the arc current flow.

Abstract: In an over-voltage protection device which includes a plurality of stacks of series-connected, substantially identical surge arrester sections, each comprising an insulated casing containing a voltage-dependent resistor with a spark gap assembly, which sections are mutually electrically connected at their upper and lower ends, there is provided a triggering circuit in parallel with the arrester stacks which includes a plurality of series-connected control spark gaps corresponding to the number of arrester sections in each arrester stack and a triggering resistor connected in series with the control spark gaps. Cross-connections containing triggering impedances extend from a connection point between two control spark gaps to the corresponding connection point between two arrester sections of each of the parallel stacks. Control impedances are connected in parallel with the spark gap. The triggering impedances are constituted by resistors.

Abstract: A plurality of series connected main spark gaps are connected in shunt circuit relation with a voltage grading impedance network which includes a trigger gap that is connected though frequency responsive coupling means in shunt relation with approximately one-half of the series connected main spark gaps. The trigger gap is operative, as a substantially linear function of a voltage impressed across the series connected gaps, to cause the main gaps to spark over in cascade fashion. The triggered control network allows use of a large number of main gaps but with a controlled total sparkover very much less than the sum of the sparkover of the individual main gaps, thus, providing a desirably high ratio of reseal voltage to sparkover voltage for the main gap series circuit.