Abstract: Electrical protection devices, such as for use with power systems for overvoltage protection, are disclosed. One electrical protection device includes a first electrical connection, a second electrical connection, a first electrical discharge device, and a second electrical discharge device. The first electrical discharge device includes a first conductive bus connected to the first electrical connection and a second conductive bus connected to the second electrical connection. The first electrical discharge device has a first breakdown voltage. The second electrical discharge device includes a third conductive bus connected to the first electrical connection and a fourth conductive bus connected to the second electrical connection. The second electrical discharge device has a second breakdown voltage.

Abstract: A region of a positive charge formed around an arrester is made as small as possible to effectively suppress generation of an upward streamer. An inner electrode body to be grounded, an outer electrode body provided to surround the inner electrode body with a predetermined gap, an electrical insulating layer provided in the gap to hold the inner electrode body and the outer electrode body in an electrically insulated state, and a support that supports at least one of the inner electrode body and the outer electrode body are included, in which the inner electrode body is formed in a rod shape, and the outer electrode body is formed in a cylindrical shape.

Abstract: A lightning strike simulation apparatus includes a storage device for storing lightning strike data, a setting unit for setting a simulation target in a simulation space, a downward leader advancing unit for advancing a downward leader from a lightning strike start position set by the setting unit, an upward leader advancing unit for advancing upward leaders from lightning strike-receiving candidate points set in the simulation space when a distance between a leading edge of the downward leader and a reference point is within a first threshold value, and a lightning strike point determination unit for, when a distance between a leading edge of the downward leader and a leading edge of any one of the upward leaders is within a second threshold value, determining that the lightning strike-receiving candidate point corresponding to the any one of the upward leaders is a lightning strike point.

Abstract: An apparatus body of a personal computer is provided with a cooling unit configured to cool the interior of the apparatus body. The cooling unit includes a cooling duct located between a printed circuit board and a top wall of the apparatus body and a support mechanism supporting and elastically pressing the cooling duct against at least one of the electronic components on the circuit board. A support post portion of the support mechanism is set up on the bottom wall of the apparatus body or the printed circuit board and extends toward the top wall through the cooling duct. The top wall of the apparatus body includes an abutting portion abutting against an end portion of the support post portion to prevent the top wall from being deformed.

Abstract: Air terminals of two types having curved surface electrodes that act passively or dynamically to minimize or further reduce corona during the close approach of the down leader. In the first type, a fully grounded passive terminal, suitably located and comprising a conductive curved surface of a given radius on a grounded rod of given height, is located and suitably dimensioned in order to minimize corona discharges until the median field rises to a level sufficient to support streamer to leader conversion, as described below. In the second type, dynamic action is achieved by allowing the curved surface to float upwardly in voltage by use of capacitive coupling to the approaching leader. The raising of voltage being in the same polarity as the leader, acts to reduce the electric field immediately above, with consequent reduction in corona.

Abstract: A discharge gap device which is provided between an antenna input terminal or a secondary side earth and a commercial power source, or between the power lines of a commercial power source as a ground discharge countermeasure for electrical equipments such as a television set, a video cassette recorder, and a television and video compound device. The discharge gap device functions only as a discharge gap unit and has two conductors. Normally, the conductors are not electrically connected to each other, and upon application of over-voltage, discharge occurs between the conductors; that is, the conductors are electrically connected to each other.

Abstract: An improved line arrester is disclosed that includes a non-linear resistor. The arrester includes a pair of arcing horns are respectively provided on an earth side and a line side of the arrester, with an aerial discharge gap being provided therebetween. The aerial discharge gap is in electrical parallel with the resistor. The length of the aerial discharge gap is selected such that flashover does not occur in response to currents smaller than a rated discharge current of the resistor, yet flashover does occur in response to a current that is greater than the rated discharge current, but lower than a critical discharge current of the resistor. With this arrangement the resistor is protected against the lightning surge current greater than the critical discharge current.

Abstract: A fault current limiter in which a resistor is inserted by a running arc. The arc is allowed to burn in a commutating unit until the current zero-crossing. Upon the passage through zero the arc is extinguished and the current is commutated to a shunt resistor. The commutating unit comprises a gap-formed nozzle, in which the arc is burning. The nozzle is defined by two nozzle halves of a material which gives off gas under the influence of the arc. Close to the nozzle inlet is a pressure accumulating chamber, in which an overpressure is built up during the arcing time. After current zero-crossing, the hot arc residues are effectively vented by means of the overpressure in the pressure accumulating chamber. For cooling the gas in the chamber and for guiding the gas flow, the chamber is divided into small sub-volumes defined by metal plates.

Abstract: The protection arrangement according to the invention for protecting electric installations against lightning effects is characterized in that an electric relationship between a multiphase input line and the installation includes for each of the phases at least a first set of spark-gap arresters, at least a first self-inductance coil and at least a first variable resistance lightning arrester. Such an arrangement is particularly applicable to the protection of transformation units, hertzian relays or other delicate electric or electronic installations.

Abstract: A lightning conductor having an electrically conductive surface element insulated from an earth rod. The surface element is substantially continuous, but has an aperture defining an air gap. The air gap is located near the top of the earth rod. In atmospheric conditions existing before lightning discharges, arcing occurs between the surface element and the earth rod. This creates plasma about the tip of the earth rod, leading to upward leader formation. A high impedance static drain may be connected between the surface element and the earth rod.

Abstract: There is disclosed a current-limiting arcing horn comprising a current-limiting unit and a ring horn. The current-limiting unit is composed of lower and upper electrodes, at least one nonlinear resistor element mounted between the electrodes, and an insulating member made of an insulation. The insulating member encloses the electrodes and the nonlinear resistor element. The insulating member has a certain length which is 1.5 to 3.0 times as long as the length of the nonlinear resistor element. The creepage distance of the surface of the insulating means is 1.5 to 3.0 times as long as the length of the insulating member. The grounding electrode of the current-limiting unit is fixed to the earthside base of an insulator that holds an insulated wire. The ring horn is mounted to the upper electrode. An air gap is formed between the ring horn and the insulated wire to permit a flashover by lightning surge across the gap.

Abstract: A current limiting horn device for a transmission line supported by sets of insulators suspended from arms of steel towers. The device includes horns located respectively at charging and earthing portions of each set of the insulators and spaced horizontally apart a predetermined distance from a vertical axis of the set of the insulators. At least one of the horns is provided with an arrester element of a resistance having a non-linearity. According to the invention, a ratio Z/Zo of a distance Z between the horns to a total length Zo of the one set of insulators is not more than 0.5, thereby when extraordinary voltage caused by lightening surge is applied to the transmission line, securely causing flash-over between horns to prevent any earthing accident which would otherwise occur in the transmission line.

Abstract: A current limiter for high voltage utilizes the high migration velocity of an arc for rapidly inserting at least one pair of resistive runner rails upon a short-circuit in a circuit. To be able simultaneously to fulfil the demands for a high energy absorption capacity and sufficient resistance per unit of length of the runner rails, the runner rails are made of a relatively thin, insulated tape of an electrically conductive material, which is folded and packed to form a solid resistance package. Between the two runner rails in each pair of rails there extend two parallel walls of insulating material, which form between them a narrow gap for the arc. The magnetic field in the gap is reinforced with the aid of a magnetic core and/or current loops.