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1887

IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews)

Volume 135, Issue 1, January 1988

Volumes & issues:

Volume 135, Issue 1

January 1988

President's inaugural address. Higher education, industry and Government — new rules for a ménage á trois
IEE Management & Design Division: Chairman's address. Managing a business in the public sector
  • Author(s): D.G. Jefferies
  • Source: IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews), Volume 135, Issue 1, p. 13 –21
  • DOI:  10.1049/ip-a-1.1988.0002
  • Type: Article
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  • p. 13 –21 (9)
    The paper describes some of the challenges — opportunities, problems and changes — faced by the management of a public sector electricity Board. Managers in electricity supply operate in a complex organisation and within a framework of financial controls, constraints and social obligations imposed by Government and other statutory bodies. The paper considers how a distribution Board fits into the overall industry and looks at initiatives, in terms of management and technical innovation, taken by managers to improve business performance. Aspects covered include tariffs, energy management, manpower management, finance and various factors affecting system efficiency. The industry's marketing philosophy of promoting cost effective uses of electricity is highlighted as are the particular responsibilities of having 21 million customers. Attention is drawn to the important role that corporate planning and targeting play in the overall management of a Board and the paper concludes with some general observations on how the industry's management has performed.
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New lightning flash counter and calibration circuit with improved discrimination of cloud and ground discharges
  • Author(s): E.O. Oladiran ; E. Pisler ; S. Israelsson
  • Source: IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews), Volume 135, Issue 1, p. 22 –28
  • DOI:  10.1049/ip-a-1.1988.0003
  • Type: Article
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  • p. 22 –28 (7)
    A new low-power lightning flash counter (LFC) utilising active elements (micropower ICs) is presented. Better discrimination is achieved by using a narrow frequency band, centred around the 10 kHz according to the CIGRÉ specification. A simple circuit for producing double exponential pulses of variable rise times, accompanied by a modified in situ testing circuit which gives a more definite state of the batteries and calibration stability of the system, is used to calibration various types of counters including the improved LFC. Experimental and theoretical determinations of the response characteristics of the active and CIGRÉ counter networks show a better discrimination for pulse signals than for sine signals, and an improved discrimination of the cloud and ground discharges by the active network over the passive conventional networks.
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Electrical drive simulator for teaching purposes
Design of a portable thermocouple calibrator
Ammeter induced perturbations of Argand diagrams for Debye-like dielectrics
How the electrical properties of soil affect the surge performance of buried long systems
A photon-triggered spark gap
Effect of humidity and gas density on switching impulse breakdown of short airgaps
  • Author(s): A.J. Davies ; J. Dutton ; R. Turri ; R.T. Waters
  • Source: IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews), Volume 135, Issue 1, p. 59 –68
  • DOI:  10.1049/ip-a-1.1988.0009
  • Type: Article
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  • p. 59 –68 (10)
    The dual purpose of the present work was first to examine the effect of humidity and gas density on the breakdown characteristics of short airgaps and secondly to investigate whether charge injection data could provide additional information concerning the probability of breakdown at low probability levels. Impulse tests were, therefore, performed in a sealed test vessel using laboratory air for pressures in the range 0.7–1.4 bar and absolute humidity levels from ∼ 2 to 15 g/m3. Both pressure and humidity could be closely controlled and measured. The impulse shape was + 100/2500 μs and the test gap consisted of a 5 cm-diameter sphere at 20 cm above an earthed plane. Statistical flashover tests and measurements of apparent charge injection at the sphere were made and both sets of data were analysed using the method of maximum likelihood. The breakdown probabilities were found to satisfy a normal distribution and the charge measurements provided significant additional information at low probability levels. The measured values of V50 were found to depend linearly upon absolute humidity with a slope of 1.5 kV/g/m3 at all pressures. The withstand voltages, on the other hand, were only weakly dependent upon absolute humidity. The humidity correction factors found in the present work agree well with the IEC standard at 1.2 and 1.4 bar, but depart appreciably at lower pressures.
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Arcs in boundary layer flow
  • Author(s): S. Au  and  P.R. Smy
  • Source: IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews), Volume 135, Issue 1, p. 69 –75
  • DOI:  10.1049/ip-a-1.1988.0010
  • Type: Article
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  • p. 69 –75 (7)
    Measurements of the electric field generated in an arc, when it is driven by high-speed flow onto the edge of a plate whose surface lies parallel with the flow, are found to be in good agreement with previous theoretical calculations. Conventional and streak photographs confirm the boundary layer configuration assumed in the theory. The same theoretical and experimental approach has been extended to include the case of an array of plates, as might occur in some types of air-blast circuit breaker. Here the applicability of the theory is more open to question, but, in fact, quite reasonable agreement is obtained between theory and experiment. The various hydrodynamic forces tend to increase the width of the arc, while the heat loss effects tend to reduce this quantity. In practice, it is found that, over a range of values of current between 30 and 300 A, the width-to-thickness ratio remains in the range of two to three.
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Surface recombination of ions and cratering by ion impact
Statistical analysis of flashover data using a generalised likelihood method
  • Author(s): A.J. Davies ; A.R. Rowlands ; R. Turri ; R.T. Waters
  • Source: IEE Proceedings A (Physical Science, Measurement and Instrumentation, Management and Education, Reviews), Volume 135, Issue 1, p. 79 –87
  • DOI:  10.1049/ip-a-1.1988.0012
  • Type: Article
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  • p. 79 –87 (9)
    In order to ensure consistency in the treatment of flashover data, it is desirable that a standard method of analysis of test results be established. Previous workers have suggested that the maximum likelihood method would be appropriate for estimating the parameters of the breakdown probability distribution, such as V50 and σ in the normal distribution. The present paper shows how this method may be applied in practice and can be extended to determine the confidence region associated with sets of parameters, and the confidence interval on a single parameter. It is also shown how other parameters, such as the voltage level corresponding to a specified probability of breakdown, may be determined. An example is given of the application of the method to a typical data set for flashover in air together with a listing of a suitable computer program in Fortran 77. It is recommended that this method be considered for adoption as a standard procedure.
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