Abstract: A protection circuit for a power converter apparatus is disclosed which is made up of plural unit circuits, each comprising at least one fuse connected in series with a semiconductor element, such as a thyristor, and a non-linear resistor connected in parallel at least with the fuse. In this way fuses can be employed in a power converter apparatus of high voltage and current capacity. The unit circuits can be connected in series or in parallel or both to increase the current and/or voltage capacity of the power converter. Trigger fuses can be employed to halt operation of the unit in the event of fusing of one or more of the fuses.

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: Electrical distribution apparatus, such as a pad-mounted electrical distribution transformer, which has an electrically grounded tank or casing. A surge arrester assembly includes a housing, and a draw-out surge arrester having first and second insulatively spaced electrical contacts, with the draw-out surge arrester being removably disposed in the arrester housing. The arrester housing has first and second insulatively spaced metallic end members, with the first metallic end member functioning as a mounting structure for mounting the arrester housing in a tank opening, and as an electrical contact which automatically connects the first electrical contact of the draw-out surge arrester to the grounded tank of the apparatus to be protected. The second metallic end member of the housing electrically connects the second electrical contact of the draw-out surge arrester to an electrical circuit point within the tank to be protected against voltage surges.

Abstract: At least two platelike electrodes are arranged on the two major surfaces of a platelike varistor element having rounded sides and corners. A pair of external electrodes are formed on the two major surfaces and are connected to the platelike electrodes. The platelike electrodes partially overlap each other. The portion of the varistor element, sandwiched between the overlapping portions of the electrodes, provides varistor characteristics.

Abstract: An electrical assembly comprising a plurality of electrical components aligned in a row under an axial load and wrapped with filament windings. The wrapped components are then preferably enclosed in a housing. MOV blocks can be used as the electrical components, resulting in a surge arrester having excellent heat transfer properties as well as improved tensile and cantilever strengths. The electrical components can be varistors, resistors, capacitors and insulators or any combination thereof.

Abstract: A series capacitor bank for connection into an electric power supply network is provided with overvoltage protective equipment having two branches connected in parallel with the capacitor bank. The first branch comprises a first zinc oxide varistor in series with a linear resistor and the second branch comprises a varistor with a higher "knee" voltage than the first zinc oxide varistor. The resistance of the linear resistor is preferably of the same order of magnitude as the absolute value of the impedance of the capacitor bank at the operating frequency of the power supply network. The "knee" voltage of the second varistor is at least 1.15 times (and preferably not more than 2.0 times) the "knee" voltage of the first varistor.

Abstract: A surge protection device for protecting an electric power system from excessive voltage surges, including those caused by direct lightning strikes. Metal oxide varistors are wired between each incoming 115 volt power line and ground and between the two power lines. The varistors connect with the power lines on the user side of the main circuit breakers. The varistors are normally nonconductive but become conductive when excessive voltages are present on the power lines. Then, short circuits are established through the varistors to protect downline equipment. The varistors are embedded in a pliable filler material which fills a rigid polymeric shell. In the event of a direct lightning strike, the surge protector is destroyed sacrificially and the pressure resulting from the failure is relieved through the opposite ends of the shell.

Abstract: This filtering transient voltage suppression device assembly adequately pides for filtering of electrical noise and transients. It also provides a circuit with reduced parasitic inductance of the voltage suppression device (VSD). It provides for connector units to be mounted in planes at each end of the assembly. This mounting arrangement enables bulkhead mounting of the FTVSDA. Filters and VSD's are connected, in a low parasitic inductance fashion, between leads interconnecting separate connector pins and the body of the device. A mounting plate inside the device provides structure and electrical connections for assembly, as well as easy access.

Abstract: In a feed-through unit of a conductor (2) through an opening in a conducting wall, the conductor together with shunt elements connected between the conductor and the wall--which shunt elements have a first and a second contact surface with a conducting coating--forms a rotationally symmetrical or mirror symmetrical configuration which completely or substantially closes the opening.In order to guarantee an even thermal stress on the individual shunt elements, the latter are so formed that the first contact surface and the second contact surface run parallel and the shunt element is located in each case essentially between the two contact surfaces. Several shunt elements can be arranged in shunt rows, whereby successive shunt elements are seriated either directly or separated by conducting intermediate layers.

Abstract: A zinc oxide lightning protector, wherein end plates are mounted at the ends of an insulator and a zinc oxide element section is arranged between the cover plates. Support metal members are mounted on the cover plates between the zinc oxide element section and the insulator to support an insulation cylinder therebetween. A space is formed between at least an end of an insulation cylinder and a corresponding cover plate to absorb the expansion or contraction of the insulation cylinder due to temperature changes, thus preventing the insulation cylinder from deforming. The elements are eccentrically arranged against the insulation cylinder, to thereby cause the gas flow along peripheral direction so that the laminar flow is changed into a turbulent flow. Thus, the heat conduction is improved to improve the radiation characteristic of the zinc oxide element section.

Abstract: A metal oxide type surge arrester is provided with a plurality of arrester blocks in series within a housing having, in addition to line and ground terminals at the extremities, a bushing providing a tap voltage terminal intermediate the series stack such as between the bottom two arrester blocks. The provision of the voltage tap and a shunt resistance in series with the ground terminal permits respectively detecting the voltage and the current of the arrester so that they can be compared and their phase relation observed to determine if the arrester blocks are maintaining a capacitive characteristic or have become resistive. In addition, several other methods of use of such an arrester for monitoring line voltage, energy absorption, fault current and the like are disclosed.

Abstract: A lightning arrester insulator in which a voltage non-linear resistor having a major constituent of zinc oxide is integrally fixed in a longitudinal bore in the insulator with a layer of an inorganic adhesive agent which is interposed between an outer surface of the resistor and an inner wall surface of the insulator defining the longitudinal bore. A contact angle of the adhesive agent layer defined by each end face thereof and an associated end part of the inner wall surface is held within a range of 10 to 60 degrees. To establish the contact angle, at least one of the end face of the adhesive agent layer and the associated end part of the inner wall surface of the insulator is inclined with respect to the longitudinal centerline of the longitudinal bore. Each end surface of the voltage non-linear resistor is spaced from the corresponding end of the adhesive agent layer axially inwardly along the longitudinal centerline of the longitudinal bore.

Abstract: A surge arrester includes an elongated insulating housing comprising one or more stacks of electrically series-connected metal oxide varistor blocks arranged between a top terminal and a bottom terminal. To achieve a more even voltage distribution in the longitudinal direction of the surge arrester, the surge arrester comprises larger varistor blocks at the top terminal than at the bottom terminal.

Abstract: A low voltage valve type arrester device for connection between a domestic electric supply line and earth includes a varistor, a switching device and an encapsulated gas discharge voltage arrester connected in series. The switching device includes two switch members connected together by a solder connection and biased apart by a spring. A fusible link is connected to the two switch members in parallel with the solder connection. When a voltage surge occurs, current flows through the arrester to earth. If the surge is large enough to render the gas discharge arrester continuously conductive, the solder connection melts due to the heat dissipated in the varistor and the two switch members move rapidly apart. The fusible connection rapidly melts by which time the switch members are sufficiently far apart for no arc to form between them.

Abstract: A lightning arrester comprises nonlinear resistance discs 2 stacked within a ceramic casing 1, with annular metal cover rings 3, 4 being fixed to the opposite outer ends of the casing. Conductive plates 5, 19 having reduced thickness rupturable central portions are sealed to the inner ends of the casing, with the lower plate 19 being insulated from the lower ring 4 by an insulating ring 20. An ammeter 16 is connected between the conductive plate 19 and ground by a lead wire 21 passing through the ring skirt but insulated therefrom, whereby only leakage current passing through the nonlinear resistance discs is sensed.

Abstract: A lightning arrester comprises a plurality of column blocks disposed in parallel each of which has groups of a number of stacked nonlinear resistance elements and spacers interposed between the element groups, in which the element groups of the blocks are electrically connected in series by jumper conductors so as to form a series resistance and the spacers are formed of nonlinear resistance elements which can absorb energy, so that the arrester, as a whole, can absorb a larger amount of energy.

Abstract: To record significant discharges of a surge arrester, the energy dissipated in a separate varistor element equivalent to the varistor elements in the arrester and connected in the arrester discharge path is monitored. When an arrester discharge results in a temperature increase above a predetermined minimum in the separate varistor element, heat sensing means thermally coupled therewith triggers a counter to record the event.

Abstract: An electric switching surge protector comprising a non-linear, voltage and frequency sensitive RC network connectable between earth and a phase of a switch controlled, AC electric load circuit. The RE network includes a linear resistance component; a non-linear resistance component connected in parallel with the linear resistance component and having a pre-determined knee-point voltage value; and a capacitance component connected in series with the parallel connected linear and non-linear resistance components. The capacitance component is operative to decouple the resistance components from the circuit at power supply frequency but to couple the combined resistive impedance of the parallel connected linear and non-linear resistance components effectively into the circuit under high frequency conditions. The capacitance component is further operative to increase the rise time of that portion of a steep fronted surge which exceeds the knee-point voltage value of the non-linear resistance component.

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 arrester comprises two or more surge arrester units which are electrically series-connected between a top terminal and a bottom terminal. Each surge arrester unit comprises a stack of metal oxide varistor blocks, the latter being distributed within the surge arrester so that the number of varistor blocks per unit length in the surge arrester unit which is nearest the bottom terminal is less than in the surge arrester unit which is nearest the top terminal. This enables a more even temperature distribution to be achieved throughout the length of the surge arrester especially in the case where the surge arrester is located where it is subjected to long-term external fouling or pollution.

Abstract: A surge arrester having a first non-linear resistor block, a second non-linear resistor block connected in series with the first non-linear resistor block, a bypass gap connected in parallel with the second non-linear resistor block, and a linear resistor connected in parallel with at least one of the first and second non-linear resistor blocks.

Abstract: An elongated, insulative tube of high mechanical strength is equipped with fittings at each end for electrical connection with a high voltage transmission line and a grounded tower. An external spark gap is provided between a first arcing ring mounted in electrical connection with one end fitting and a second arcing ring mounted to the tube intermediate its ends and electrically connected with a contact member disposed within the tube. The portion of the tube interior between the contact member and the other end fitting is packed with a series array of varistor discs. The tube maintains the line in spaced relation with the tower, while the varistor array and spark gap absorb voltage surge differentials between the line and tower.

Abstract: A surge arrester including an outer porcelain housing and an ablative heat shield liner is disclosed herein along with a number of techniques for making the surge arrester break resistant. In accordance with one of these techniques, a blow out or relief valve is provided on at least one end of the arrester housing for venting internal pressure due to electrical arcing therein. In this embodiment, an arrangement is provided for preventing the components therein from escaping during the venting procedure. The liner is constructed of a material which is sufficiently ablative to produce its own gas within the housing in response to electrical arcing therein.

Abstract: An elastomeric insulated fully shielded arrester including one or more surge arrester blocks mounted within an elastomeric housing having a layer of conductive material on the outer surface thereof, an electrically conductive contact at each end of the arrester block, the elastomeric housing providing a compressive force for maintaining electrical communication between the electrical contacts and the block or blocks and closely engaging the outer surface of the block or blocks to minimize corona discharge.

Abstract: A zinc oxide varistor disc is provided with one or more circumferential recesses in its rim to reduce the current density at the edges of the electrodes on the opposed disc faces, which electrodes are of a lesser diameter than the varistor disc. It has been discovered that optimum results are achieved when the diameter at the bottom of the recess is somewhat less than the diameter of the electrodes.

Abstract: A nonlinear resistor comprising a sintered body containing zinc oxide as a major component and at least bismuth oxide and boron oxide and electrodes formed thereon, said sintered body having a higher .gamma.-form bismuth oxide phase concentration in upper and/or lower surface layers of the sintered body than in the inner portion of the sintered body, has stabilized properties against long-time voltage application. When the sintered body is further modified by making the .gamma.-form bismuth oxide phase concentration in the periphery portions of the upper and/or lower surface layers lower than that in the inner portions of the upper and/or lower surface layers, the resulting nonlinear resistor shows a higher long-duration current impulse withstand capability.

Abstract: A voltage surge arrester utilizes a triangular shaped housing for accommodating up to three varistor elements respectively arranged on edge along the three planar sidewalls of the housing. The varistors are held in place by a resilient contact clip commonly engaging the inwardly faced varistor electrodes. Separate contact strips disposed between each varistor and the housing sidewalls engage the outwardly faced varistor electrodes. Line leads individually electrically connected with the contact strips and a ground lead electrically connected with the contact clip are brought out through an opening in the housing.

Abstract: This surge suppressor comprises a tubular insulating housing having a metal end cap at one end and an integral end wall at its opposite end. A metal terminal extends through the end wall and has a portion within the housing. A stack of metal-oxide varistor blocks has one end bearing against said terminal portion and an external periphery spaced from the surrounding wall of the housing. A metal plate at the other end of the stack is urged against said other end of the stack by a spring between the end cap and the plate. A plurality of ceramic rods fixed to the end wall extend alongside said stack and through holes in the end plate and serve to limit such lateral motion of the stack as produced by vibrations and mechanical shocks.

Abstract: A surge absorber of a construction having a voltage non-linear resistive element composed of an oxide, a pair of electrodes attached to both surfaces of the resistive element, a lead wire connected to one of the electrodes, and a terminal plate fastened to the other electrode and having a plurality of fitting holes formed in one part thereof, the combination of the resistive element, the electrodes, and a part of the terminal plate and the lead wire being covered with a resin coating layer.

Abstract: In the case of a surge arrester, enclosed in an electrically conductive, grounded enclosure, and having disc-shaped arrester elements (2), stacked one above another to form at least one column, and having screening and controlling bodies in order to produce a linear potential-distribution along the active portion (3), the object is to achieve a good distribution of the electric field by simple means, even in the case of surge arresters which are built in small series. This object is achieved by providing electrically conducting coatings (6), as the screening and controlling bodies, these coatings being electrically insulated from each other and being wound into a body (5), composed of insulating material, and surrounding the active portion (3) of the arrester approximately concentrically.

Abstract: An overvoltage surge arrester which has a reduced turn on time and is suitable for use at low voltage levels to protect electronic equipment, such as telephone repeaters and the like; this protective device includes a core of semiconductor material provided with a predetermined surface creepage path thereacross and electrically conductive terminals (electrodes) disposed on each end thereof. The conductive terminals or electrodes may extend towards each other to provide a secondary, backup discharge gap. The surge arrester may be used as an integral part of a gas filled device with the conductive electrodes connected between a line electrode and ground electrode thereof.

Abstract: An arrester having at least two stacks of non-linear resistors connected in series, an arcing gap device connected to shunt one stack of resistors when the gap means sparks over, and a hermetically sealed housing enclosing the resistor stacks and arcing gap device and filled with sulfur hexafluoride gas having a gauge pressure not less than 2 kg/cm.sup.2. The impedance of the one resistor stack is from about 15% to about 35% of the total impedance of the two resistor stacks when the arcing gap means sparks over, and the rated voltage of the arrester is not less than about 50 KV.

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: Disclosed is a stacked resistor device particularly for high-voltage installations. The resistor device includes inner and outer annular resistance elements of different diameters which are adjacently disposed along a common axis to form a stack. The resistance elements are electrically connected by annular-shaped contact elements. The contact elements include an annular recess of larger diameter on one side for receiving the outer resistance element and an annular recess of smaller diameter on the other side for receiving the inner resistance element, and include a central cutout through which a clamping sleeve of plastic material is inserted. Bushings and clamping parts are disposed at opposed ends of the sleeve to clamp the resistance elements and contact elements together to form the stacked resistor device.

Abstract: In a surge arrester comprising a stack of series-connected cylindrical ZnO-varistors in an insulating housing, the envelope surface of each varistor is provided with an insulating protection means, which overlap varistors positioned adjacent to each other. The protection means prevent the varistors from being mechanically damaged during handling, provides guiding for the varistors in the stack, and seals the stack of varistors, so that a local glow discharge or a fault in individual varistors will not lead to an arc flash-over along the stack.

Abstract: A lightning arrester comprises a non-linear resistor as a lightning arrester element and an insulator holding the non-linear resistor in one body without a gap to prevent deterioration of the non-linear resistor caused by moisture.

Abstract: A high voltage d.c. power transmission system utilizes a metallic return conductor for carrying return current between converters at opposite ends of the system. The return conductor is connected to earth ground at one end of the system and is otherwise insulated from earth ground so that its opposite end is floating with respect to d.c. The return conductor has no capacitor connected from earth ground thereto of a size capable of limiting the voltage thereon. But connected between said opposite end of the return conductor and earth ground is a valve-type surge arrestor having a primarily zinc-oxide valve element and no gap in series therewith. This surge arrestor has a protective level that is reached by the overvoltages produced by the normal operating transients of the system, such as those produced by system start-up and commutation failures.

Abstract: Capacitance grading is provided within gas insulated lightning arresters containing stacked zinc oxide varistors by means of a grading ring electrically connected to the line terminal or, for arresters of the higher voltage ratings, by means of a plurality of telescoping external electrostatic shields. The shields are arranged so that the degree of overlap between sequential shields decreases from the line end to the ground end of the varistor stacks. The capacitance grading is provided by the degree of overlap between the sequential shields and the ratio of the radii of the overlapping shields.

Abstract: A discharge counter and arrester current meter employs a zinc oxide disk in combination with a pair of bridge rectifiers to accurately determine surge arrester steady state current and to count the number of discharges occurring through a voltage surge arrester. The discharge counter and meter circuit, connected between the surge arrester and ground, monitors the steady state current by means of an ammeter and records the number of discharges by means of a capacitor, cyclometer coil, and a recorder. The meter circuit and the discharge counter are uniquely protected by a single zinc oxide disk during the discharge of high current surges.

Abstract: A heat transfer arrangement for zinc oxide varistors comprises a metal heat sink disk held in contact with one face of the varistor by means of a circumferential elastic sleeve. The heat generated within the varistor rapidly conducts into and is absorbed by the metal disk and transmits through the elastic sleeve to the environment. When the varistor heat sink assembly is mounted within a surge voltage arrester, a flexible positioning member holds the assembly tightly against the arrester housing for transferring the heat to the housing.

Abstract: The overload protection material of this invention comprises a plastic preferably an elastomer, e.g. silicone rubber, homogeneously and highly loaded with silicon carbide particles (powder) and a lesser amount of a Group IV B element-carbide particles (powder). The material is preferably form stable and is placed (across) a semiconductor junction or between electrodes of a device to be protected so that when high voltage surges appear across the junction or device to be protected the material breaks down (conducts) before the junction or device is destroyed. The material is bidirectionally conductive in its voltage threshold characteristic and repeatedly recovers unlike a fuse so that it provides continuous high voltage over-voltage (e.g. surge) protection.

Abstract: A series circuit of a gap section and a valve block is connected between a transmission line and the ground. The valve block consists of a plurality of nonlinear resistor elements connected in series. A first impedance circuit consisting of a resistor and a capacitor connected in series is connected in parallel to the gap section. Also, a second impedance circuit consisting of another resistor and another capacitor connected in parallel is connected in parallel to the valve block. The ratio of the voltage applied across the gap section to that applied across the valve block is determined by the ratio of the impedance of the first impedance circuit to that of the second impedance circuit. A pair of discharge electrodes included in the gap section, which are a prescribed distance apart from each other, comprise a narrower gap region at which spark is started.

Abstract: A lightning arrestor comprising at least two stacks of resistor disks juxtaposed within a housing and electrically connected in parallel. The stacks include the same number of disks, at least 35, and preferably 100 or more. Each stack comprises at least two sub-stacks which are aligned end-to-end and electrically connected. Adjacent sub-stacks of parallel stacks are mechanically connected but electrically insulated from each other.

Abstract: Disclosed is a voltage non-linear resistor comprising a sintered body composed mainly of zinc oxide, said sintered body including confronting main faces and a face side face connecting the main faces to each other, which has the side face coated with a coating glass layer containing barium oxide. The coating glass layer comprises 40 to 85% by weight of lead oxide, 3 to 25% by weight of boron oxide. 1.5 to 25% by weight of silicon oxide and 0.2 to 15% by weight of barium oxide. The barium oxide acts as a catalyst and exerts a function of completely burning an organic binder at a temperature lower than about 400.degree. C. where the reaction between the organic binder and zinc oxide is not substantially advanced.

Abstract: In an enclosed-type zinc-oxide surge arrester with a grounded tank filled with an insulating medium, and a non-linear resistor assemblage which is connected at one end to a high voltage conductor and at the other end to the ground potential portion within the grounded tank, two or more ring-like shield means such as shield rings are disposed on the high voltage conductor side of the non-linear resistor assemblage at given distances. The use of the ring-like shield means makes more uniform the voltages shared by the respective non-linear resistors. The ring-like shield means may be formed with the configuration and diameter, and the number of them used being properly selected.

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: An arrester comprises a plurality of blocks connected in parallel between first and second connecting metal plates and each comprised of a plurality of stacked nonlinear resistor elements, at least one block comprised of a plurality of stacked nonlinear resistor elements and connected between the second connecting metal plate and a third connecting metal plate grounded, and a discharge gap connected in parallel with the later-mentioned block and between the second and third connecting metal plates. The discharge gap is provided below one of the blocks connected in parallel between the first and second connecting metal plates.

Abstract: A surge arrester is disclosed for a plurality of lines which are to be commonly safeguarded. In order to produce a multi-link arrester for the above application, for each of a plurality of lines which are to be safeguarded, there is provided an individual arrester to which a common arrester is connected in series. The response characteristics correspond to those of a gas discharge multi-link arrester having a common gas chamber. A capacitor is connected in parallel to the common arrester. The individual arresters and the common arrester are arranged in a beaker which is designed as a plug. A metal plate serves in the interior of the metal beaker as an electrode terminal in common to all arresters. The metal plate along with the metal beaker forms the capacitor.

Abstract: An overvoltage protective device comprises an insulating housing accommodating thereinside at least one column of non-linear resistors and a dielectric bush, both of which are closely enveloped by thermally conductive dielectric bulk material being in contact with the inner surface of the insulating housing. The wall of the housing of the dielectric bush is provided with through openings blocked by a layer of dielectric material. The inner surface of the dielectric bush forms a gas vent channel arranged lengthwise with respect to the column of non-linear resistors.

Abstract: An assembly for mechanically protecting and electrically insulating metal oxide varistor disks from the generally cylindrical inner wall of a porcelain housing of a surge arrestor. Each assembly comprising a flat metal disk having a diameter less than that of the inner wall of the housing and a plurality of resilient, electrically non-conductive spacer members mounted around the periphery of the disk for supporting the disk vertically in the housing.