Abstract: This invention is to provide a transforming system capable of satisfactorily protecting the equipment of a substation even if a aerial electric power lines is struck directly by an intense electric shock of a large energy, such as an electric shock of a waveform similar to that of a thunderbolt stroke having a long duration of wave tail. So, this invention, a transforming system comprises, a lightning arrester, a ground fault device installed near a service entrance through which the power lines are led in, a voltammeter placed on the gas-insulated switchgear, and a control device receiving a signal from the voltammeter and providing a signal for controlling the grounding device. And when detecting of said thunderbolt arising in said aerial electric power line, a control device which order said ground fault device to make the ground fault condition.

Abstract: Provided is an arrester excellent in a limit voltage characteristics which can withstand a contamination phenomenon of a porcelain bushing surface, and a surge absorption. Metal plates each having a thickness greater than a zinc oxide element portion does using high withstand voltage zinc oxide elements are arranged to suppress a rise in temperature of the zinc oxide elements. By employing the above means, it is possible to realize an arrester capable of suppressing a rise in temperature of the zinc oxide elements and which is low in a limit voltage and has higher performance.

Abstract: In a lightning protection system for a wind power generation installation, a conductor ring 16 is provided on a wind mill vane 1 and at a rotor casing 6 incorporating a wind power generator 3 a zinc oxide element 18 is provided so as to face the conductor ring 16 with a spark gap 17, thereby, if a lightning in winter season which causes to flow a large current for a long duration time hits the wind mill vane 1, the wind power generation installation is effectively protected.

Abstract: A tank-type surge arrester includes a zinc oxide element unit having zinc oxide elements, a top shield ring for earth insulation control disposed on top of the zinc oxide element unit, an upper shield ring disposed below the top shield ring in an upper section of the zinc oxide element unit, an expanded lower shield ring disposed below the upper shield ring in the upper section of the zinc oxide element unit, and tubular conductors disposed between the upper and the lower shield rings so as to be included in a vertical plane on an extension of a high-tension conductor.

Abstract: A mounting construction of a tank-type lightning arrester for a neutral point of a transformer includes a transformer having a transformer winding contained within a transformer tank, the transformer winding having a neutral point, and a tank-type lightning arrester having an overvoltage protection element contained within a lightning arrester tank. A first opening is formed in an upper portion of a side surface of the transformer tank, and a second opening is formed in the lightning arrester tank, and the first and second openings are connected together through an insulating spacer having a central conductor, and the neutral point of the transformer winding is connected to the overvoltage protection element via the central conductor. The lightning arrester tank is supported solely by a mounting portion provided on a side surface of the transformer tank.

Abstract: A ceramic resistor includes zinc oxide as a main component, and as essential components, aluminum oxide 3.0-40 mol %, magnesium oxide 2.0-40 mol %, silicon oxide 0.1-10 mol %, and at least one kind of compound 0.005-0.5 mol %, selected from a group consisting of calcium oxide, strontium oxide and barium oxide, and has a positive temperature coefficient of resistance. A neutral grounding resistor and a gas circuit breaker, each using the above-mentioned ceramic resistors, are disclosed.

Abstract: The discharge capability of zinc oxide elements is determined. A current of a given energy quantity is allowed to flow through a zinc oxide element to generate heat. The element is photographed by a camera and the temperature distribution of the element is obtained from the photographed image. The maximum temperature and the minimum temperature are determined and simultaneously the distance l between the points which show both the temperatures is determined. The difference .DELTA.T between the maximum temperature and the minimum temperature is divided by the distance l to obtain an index .DELTA.T/l. The relation between the index and the discharge capability is previously obtained and this relation is stored in a memory. Using the stored relation, a discharge capability corresponding to the obtained index is obtained.

Abstract: A mixture of calcinated metallic oxides are mixed with ZnO and SiO.sub.2, granulated, compacted and then sintered to form a nonlinear resistor. After sintering, the formed ZnO resistor elements are heat treated, preferably in a two-step heat treating process.

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: The arrestors of a compact gas insulated switchgear are to be connected to gas insulated main buses. The arrestors represent three phases, and are arranged in such a manner that the distance from a main bus which is located at the outermost position among a plurality of main buses to at least one arrestor for one phase is differentiated from the distances from the outermost main bus to at least one of the remaining arrestors. As a result, the area or the width required for installing the arrestors is minimized, the length of the main buses is shortened, and the installation area of the gas insulated switchgear as a whole can be reduced.

Abstract: In order to provide an arrestor for a gas insulated switchgear in which the voltage share rates of respective zinc oxide non-linear resistance elements are made uniform, in an arrestor constituted by a plurality of columns for a gas insulated switchgear, the thickness or the capacitance of insulator spacers contacting the high voltage terminal or the ground terminal in respective columns is controlled, whereby the potentials of the zinc oxide non-linear resistance elements close to the high voltage terminal or to the ground terminal in the respective columns are shifted close to the potentials of the high voltage terminal or the ground terminal.

Abstract: It is an object to provide a lightning arrester having machinery built-in in which an axial length of an insulating tube which stores therein zinc oxide elements is reduced so that an attempt is made for miniaturization. The arrangement is as follows. That is, a metal cap with an inclination portion 11 which is fixed to one end of the insulating tube 4 which stores therein the zinc oxide elements 5 is made to a dish shape which projects toward the anti-side of the zinc oxide elements, openings 11a are formed in the inclined portion thereof so that the inside and the outside of the insulating tube 4 communicate with each other, an insulating medium is circulated through the openings 11a while a sufficient gap L is formed between the one end of the insulating container 4 and a ground bracket 15, and the zinc oxide elements 5 are cooled by the insulating medium.

Abstract: The grounding tank 2 is laid on its side in the state that the covers 7A and 7B of the openings 3A and 3B at the both ends thereof are removed and the truck 8 is turned so that the side frame 8b on the back of the truck 8 and the bottom 8a with the wheel 11 are reversely positioned so as to mount the divided arrester units 7A and 7B to the tank 2 and the cover 7A (7B) and each arrester unit 4A (4B) are mounted and fixed to the side frame 8Ab, 8Bb so that they can be mounted and removed in the integrated state. The cover 7A (7B) and each arrester unit 4A (4B) are lined up in a horizontal line at the same height as that of the openings 3A and 3B of the grounding tank 2 after the truck 8 is turned and returned to the normal posture. The arrester units 4A and 4B are inserted and set into the grounding tank from side by moving the trucks 8A, 8B and the covers 7A and 7B are removed from the truck 8A, 8B and mounted on the tank 2 side so that they close the openings 3A and 3B at the same time.

Abstract: An arrester has a plurality of laminated columns arranged in parallel, each having a plurality of nonlinear conduction elements. The columns are electrically interconnected by conductive connection members so that a conduction path is defined by the conduction elements and the connection members. The columns are arranged around, and in contact with, an insulating support column, which provides mechanical strength for the arrester. A plurality of such arresters may be arranged in an array, the arresters being interconnected by further insulating support columns. The laminated columns also contain insulating spacers and the spacers of two or more laminated columns may be rigidly interconnected. The arresters may be mounted in a casing filled with an insulating gas.

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: Disclosed is a lightning arrester provided for a power transmission line so as to prevent damage to a line-supporting insulator string due to lightning stroke. A lightning arrester unit is fixedly supported on a fitting fixed to an arm structure of a tower in a relation in which its grounded side is electrically insulated from the fitting, and an operation detection device is connected between the grounded side of the lightning arrester unit and the fitting. The operation detection device is in the form of an operation indicator, a flashover indicator and/or an operation recorder. In the event of impartation of a lightning stroke, the operation detection device detects lightning current flowing from the grounded side of the lightning arrester unit toward the fitting.

Abstract: A composite sintered oxide resistor comprising crystal grains of zinc oxide and crystal grains of a zinc oxide compound of other metal or semi-metal element than zinc, and a grain boundary layer having an electric resistance equal to or lower than that of the crystal grains of zinc oxide between the individual crystal grains and which has a very large withstanding capacity against switch surge, a small non-linear coefficient of voltage in the voltage-current characteristics, a positive, smaller resistance-temperature coefficient, and a small percent change in resistivity after heat treatment at 500.degree. C. in the atmosphere.

Abstract: A connecting apparatus includes a connecting conductor for connecting a supporting insulator supporting an overhead transmission line and a lightning arrester through a disconnecting member. The connecting conductor includes at least first and second conductor segments having given lengths. The first conductor segment connected to the lightning arrester is greater in bending strength than the second conductor segment connected to the disconnecting member.

Abstract: A composite sintered oxide resistor comprising crystal grains of zinc oxide and crystal grains of a zinc oxide compound of other metal or semi-metal element than zinc, and a grain boundary layer having an electric resistance equal to or lower than that of the crystal grains and which of zinc oxide between the individual crystal grains has a very large withstanding capacity against switch surge, a small non-linear coefficient of voltage in the voltage-current characteristics, a positive, smaller resistance-temperature coefficient, and a small percent change in resistivity after heat treatment at 500.degree. C. in the atmosphere.

Abstract: A transmission line protection system arranged such that a leakage current detector is provided at an end of an insulating device such as an insulator connected at one end to a corresponding one of arms of a steel tower and connected at the other end to a transmission line of each phase, thereby detecting an arrester leakage current flowing in the transmission line of each phase, an output signal of the leakage current detector being led to a repeater through an optical fiber cable, an output of the repeater being transferred to a control/supervisory board in a substation through an optical fiber cable. In the control/supervisory board, preferably, a received digital signal which was converted from an analog signal at said leakage current detector is displayed on a cathode ray tube. In such an arrangement, it is possible to smoothly perform supervision of the status of the transmission lines without causing maloperations due to influences from the transmission lines.