Abstract:
An improved lightning conductor (1) is provided which has an earthed conductor element (11) surrounded by a rounded conductive surface element (12), a high impedance bleed circuit (17) connected between the conductive surface element (12) and earth, and a triggering electrode (14) positioned adjacent or above the upper end of the conductor element (11) and connected electrically to the conductive surface element (12). The conductor element (11) is preferably a tube with the triggering electrode (14) disposed on the central axis of the tube. An insulating spacer (15) is provided between the tube (11) and the triggering electrode (14). In use, the rounded surface element (12) minimises the produciton of corona and the high impedance bleed circuit (17) delays the production of a triggering arc between the triggering electrode (14) and the earthed conductor (12) until the rapid approach of a lightning down leader. The triggering arc, which occurs at the highest point of the lightning conductor (10), causes a stepped increase in the near electric field above the conductor (10) to provide ideal conditions for upleader initiation and propagation.
Abstract:
An overvoltage protection circuit is provided for protecting electrical equipment from transients on power lines (41, 42). The circuit has a string of series-connected silicon avalanche diodes (SADs) (40) connected across the power lines (41, 42) to provide an initial clamping threshold before energy-absorbing modules (43a, 43b, 43c) come on line to provide secondary clamping. The modules (43a, 43b, 43c) include a number of metal oxide varistors (MOVs) (44) connected in parallel and a switching device in the form of a gas arrester (45) connected in series with the MOVs (44). A resistance (46) is connected in parallel with the gas arrester (45) to form a high pass filter with the natural capacitance of the MOVs (44). This maintains the voltage across the resistance (46) well below the switch operating level during normal conditions and enables a component such as a 230 V fast acting gas arrester (45) to be used. In an alternative embodiment, the gas arrester (45) may be replaced by a solid state swich, such as a Sidator or a Triac.
Abstract:
The present invention relates to the technology of igniting spark gaps, particularly lightning arresters. The present invention also relates to lightning protection and transient protection. The present invention has many applications, such as electrical transmission lines, electrical supplies and sources, and telecommunications. One aspect of the present invention is directed to using a matrix transformer for the triggering of spark gaps. In a further aspect of the present invention the secondary conductor of the matrix transformer is folded back on itself so that, in the saturated mode, the magnetic linkage between the forward and the reverse section will act to further reduce the inductance. In a still further aspect of the present invention, there is provided a spark gap electrode, comprising at least two frustro conical sections mutually opposed, and being spaced by an insulative material, the sections having a hollow therethrough, into which a conductor can be placed.
Abstract:
A lightning downconductor (9) forming part of a lightning protection system, the downconductor (9) has an upper end connected to a lightning collector (10) through an upper termination device (11) and a lower end connected to an earthing system (15) through a lower termination (14). The downconductor (9) comprises an inner electrical conductor (3), an insulating layer (5) surrounding the inner electrical conductor (3), a resistive semi-conductive layer (6) surrounding the insulating layer (5) and a conductive layer (7) surrounding the resistive semi-conductive layer (6). A length of the conductive layer (7) is omitted or removed from the upper end of the downconductor (9) adjacent the upper termination device (11) to expose the resistive semi-conductive layer (6) as an outer layer of the downconductor (9).