Overhead distribution conductor motion due to short-circuit forces

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the Irish Branch, at Dublin, 18th November, 1948

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the Southern Centre, at Southampton, 2nd February, 1949

This chapter has introduced the important concept of insulation coordination of high voltage systems. The reader should be aware that increasing environmental and aesthetic concerns regarding the utilisation of overhead electrical power transmission lines have resulted in critical evaluation of underground alternatives and, in particular, at opportunities to further reduce the cost ratio between overhead and underground distribution and transmission systems. A joint CIGRE Working Group has been established to evaluate the influence of transient over-voltages on AC cable insulation design. Briefly, if one considers the inherent costs associated with cable systems (cable and accessories) then, by reducing the required withstand capability with improved protection devices and network design philosophy, one could develop a more economic underground system.

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the North-Western Centre, at Preston, 19th January, 1949

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the South-Western Sub-Centre and the Western Supply Group, at Taunton, 23rd March, 1949

The author's reply to the discussions on “The lightning protection of high-voltage overhead transmission and distribution systems”

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the Scottish Centre, at Edinburgh, 9th March, 1949

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the North-Eastern Centre, at Newcastle-on-Tyne, 13th December, 1948

Discussion on “The lightning protection of high-voltage overhead transmission and distribution systems” before the East Midland Centre, at Loughborough, 25th January, 1949

Downed distribution conductors in overhead distribution systems, may not be a concern for equipment, but greatly challenge the safety of persons, as well as the integrity of properties. Upstream overcurrent protective devices may not be able to detect the magnitudes of fault currents resulting from these high-impedance faults. Even though protective devices capable to detect such faults have been available on the market, not all the utilities have equipped their stations with these products, likely due to the costs. In this paper, the authors formalize the problem, and propose a possible cost-effective solution for the low-voltage over-head lines with neutral wire. Such solution includes a metal hook underneath the line conductors, supported by the pole, and connected to the neutral wire. This arrangement would cause a line-to-neutral short circuit, positively activating existing over-current devices, which can therefore disconnect the supply. Costs and possible safety issues for workers related to the installation of the device to existing overhead lines are herein also delineated.

It is necessary to detect a fault point in overhead distribution system for failure restoration. To search the fault point effectively and precisely, we apply TDR (Time Domain Reflectometry) measurement with utility-pole-distance resolution. In this method, we inject a pulse wave into distribution lines and measure the reflection. In this paper, the authors confirm propagation characteristics of overhead distribution system and compare the measurement of the reflected wave with the simulation result. Through the experiments, the authors confirm an influence of parasitic capacitances in overhead distribution facilities such as a transformer and a switchgear. When distribution facility is not connected with distribution line, the reflected wave from every utility pole and the end terminal are observed; the reflected waves from every utility pole are caused by parasitic capacitors between the distribution lines and cross arms. When distribution facility such as a transformer and a switchgear is connected with distribution line, the reflected waves caused by these facilities are observed. As a result, we confirmed that parasitic capacitances of distribution facilities affect the propagation characteristics of distribution failure pulse wave. In addition, the authors developed a simulation tool to evaluate the propagation characteristics of the pulse wave in the overhead distribution system based on the result utilizing the test distribution system, and confirmed that the simulation results corresponded to the measurement results.

This paper presents basic guidelines on design considerations for wind power plant substation and collector system based on redundancy, reliability, and economics. Design considerations, although similar to utility substation and underground or overhead distribution systems, often include aspects not normally considered for those systems. This paper will highlight design considerations unique to wind power plant design comparing economic and reliability benefits among available design options. Power loss analysis in a typical wind power plant is explained. Finally, an overall economic analysis to be considered when designing a new wind power plant is presented.

This paper presents the development of a virtual real-time test platform for intelligend electronic devices (IEDs) with high impedance fault detection function. High impedance faults are very common events in overhead distribution systems, being difficult to detect due to it’s low current magnitude. Considering the difficulty of recording oscillographies of these faults, and the availability of real-time digital simulations, this paper proposes a test platform for protection devices. In order to accomplish this, a real-time simulation platform from Typhoon HIL Inc., equipped with a Typhoon HIL 604 is used. The elaboration and validation process of the high impedance fault model proposed by Gautam and Brahma (2013) is demonstrated, testing the parameters of three different surfaces. The results reflect what is expected for high impedance faults, with the tests occuring dynamically through the accesses of the low-level interface of the used IED.

An overhead electrical system makes use of large quantities of materials which are also very vital to the nation's wartime program. This paper seeks to point out the most practical ways of conserving these vital materials, thereby releasing them in greater quantities for use in wartime production. In general, this can best be accomplished by keeping to a minimum the quantities used to make the line extensions and system reinforcements which will be required to supply electric service to the new industries and military establishments, and to the increased housing facilities which must accompany them. A number of effective tools are available which may be utilized to reduce the quantities of conductor material required to give satisfactory service. There are also possibilities of rearrangement of existing facilities so as to use them more effectively.

In recent methods on calculation of lightning trip rate, it is thought that insulator flashover in one phase could lead to trip. While in ungrounded neutral point system, only insulators flashover in two or three phases could result in trip. A new method on calculation of lightning trip rate of 35kV or under overhead distribution lines with ungrounded neutral point is proposed, consists of direct lightning trip rate and induction lightning trip rate. Couplings of grounded phase on sound phases are considered legitimately. New calculation formulas of arcing rate and induction overvoltage are adopted. Based on different methods, include traditional formulas method, modelling & simulating method with ATP, and new method proposed in this article, lightning trip rate of typical 10kV overhead distribution line is calculated. A comparison between the different calculation values and practical statistics certifies the accuracy of the new method. The research in this article contributes to the absence of an appropriate and accurate method that applies to the calculation of lightning trip rate of overhead distribution lines in ungrounded neutral point system. It also helps to estimate the level of lightning attack accident and provides references to lightning protection in engineering practice.