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HV distribution networks are generally of radial form and consist of a large number of elements. This gives rise to many possibilities of outages which can lead to large numbers of customer disconnections. Distribution Network Operators (DNOs) aim to improve automatic, post-fault outage restoration of 11kV networks to minimize disconnections and disconnection times. Several approaches have been proposed...
In this investigation, the damage caused by large-magnitude lightning impulse currents was studied in the low Amperes and high kiloamperes current ranges. For the low current up to 350A tests, 150 mm × 150 mm square carbon composite material samples with a thickness of 2 mm and having a fastener and metal ring were used. For the high current tests using the D Waveform with magnitudes up to 70kA, two...
An evaluation of the impedance of ground electrodes under dc, ac or impulse conditions requires reliable and accurate measurement of the current and earth potential rise (EPR) at the point of injection. This is commonly achieved in wired systems by arranging current-injection and measurement circuits in quadrature, but such wide-area test arrangements are not always possible due to prohibitive environmental...
In this work, the results of an experimental study of the impulse characteristic of practical ground electrodes consisting of horizontal conductors of various lengths, a grounding grid and full-scale tower footings are reported. These electrodes are installed at an outdoor test site having nonuniform soil, with equipment facilities for generating low- and high-magnitude impulse currents. The tests...
In this paper, field experiments and computer simulations of a sectionalised 88 m length horizontal earth electrode under different energisations (dc, variable frequency ac and transients of different shapes) are reported. From measurements of the voltage and current at the injection point, and by incrementally increasing the length of the test electrode, the effective length of the horizontal earth...
In this paper, the behaviour of a horizontal electrode under impulse conditions is investigated experimentally at the Cardiff University outdoor earthing test facility. The test electrode consists of 88.5 m long copper conductor buried to a depth of 30 cm, and is divided into sections with test pits located along the electrode to enable access for voltage and current measurements along its length...
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