Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887

Proceedings of the IEE - Part A: Power Engineering

Volume 102, Issue 3, June 1955

Volumes & issues:

Volume 102, Issue 3

June 1955

Sealed transformers
  • Author(s): E.B. Franklin
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 265 –272
  • DOI:  10.1049/pi-a.1955.0063
  • Type: Article
  • + Show details - Hide details
  • p. 265 –272 (8)
    Sealed transformers have certain advantages, and an outline is given of various sealing methods available. The internal pressure relations in a particular type of sealed transformer are obtained, taking into account the effect of gas solution in the oil and the chemical reaction of oxygen with the oil. A review of published experimental work shows how the electric strength of oil varies with gas pressure, and the results are applied to the operating conditions met in sealed transformers. It is shown that special precautions must be taken to avoid large negative pressures. The paper concludes by showing the derivation of the equations for pressures and estimating the effect of tank-wall deflection on the pressure.
    Add to favourites
    Export citations
Discussion on “Sealed transformers” before the Supply Section, 26th January, 1955
The author's reply to the discussion on “Sealed transformers”
The economic selection of cooling towers for generating stations
  • Author(s): Geoffrey F. Kennedy  and  P.H. Margen
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 279 –289
  • DOI:  10.1049/pi-a.1955.0066
  • Type: Article
  • + Show details - Hide details
  • p. 279 –289 (11)
    The paper describes the construction of charts showing the economic duty conditions of natural- and mechanical-draught cooling towers for generating stations in the British climate. The charts are drawn in terms of two factors, namely (a) the annual station load-factor, and (b) the full-load turbine heat-rejection per square foot of net exhaust area. Typical seasonal temperature and load cycles are assumed. The calculations indicate that past design practice often led to towers which were unduly large and water-temperature ranges which were unduly small. By correct design, net capitalized savings of the order of £200 000 per 240-MW station can be made in some instances. The advent of larger turbine units and the associated higher values of factor (b) will make higher water temperatures economic. With mechanical-draught towers, the water temperatures specified should generally be lower than with natural-draught units. A chart is constructed showing the difference in the overall costs of generation of stations fitted with natural and mechanical-draught towers. This chart suggests that mechanical-draught towers are economic only at low values of factor (b), such as those obtained on small turbines. Another chart shows the effect of varying climatic conditions on the comparison. Higher air temperatures favour mechanical draught. Circuits for combined river and cooling-tower schemes are examined. With these arrangements the cooling towers generally operate mainly during the summer season, and consequently mechanical-draught towers are often economic. Even with small rivers having widely variable discharges, such combined schemes can be responsible for substantial savings relative to pure cooling-tower schemes.
    Add to favourites
    Export citations
The application of friction/heat-transfer correlations to cooling-tower design
  • Author(s): P.H. Margen
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 290 –300
  • DOI:  10.1049/pi-a.1955.0067
  • Type: Article
  • + Show details - Hide details
  • p. 290 –300 (11)
    The thesis of this paper is that friction and heat-transfer properties of cooling-tower packings are correlated, i.e. that an improvement in the heat-transfer properties can be obtained at the expense of an increase in friction. For any given shell design and packing surface a definite friction factor will then produce the best cooling-tower performance. The precise nature of the friction/heat-transfer relation depends on the method of changing the shape of the packing, e.g. a progressive change in the alignment of corrugated sheets to produce progressively narrower constrictions in the air-flow path. The limited experimental evidence now available, however, suggests that differences between various methods are not pronounced, i.e. that the results for all film-type packings free from the more obvious design faults are reasonably well represented by a general friction/heat-transter correlation. For this correlation a chart is prepared from which the optimum friction factor, the economic packing surface per unit ground area and the corresponding cooling-tower performance coefficient can be read off for any values of two design constants, namely the air-flow resistance of the tower shell, and the comparative cost of extending the tower ground area and the packing surface. The values of these design constants are discussed for various applications, and it is shown that the optimum friction factor can vary over a range of 0.1–0.6, being lowest for small mechanical-draught towers situated on expensive ground, and highest for large natural-draught towers. Methods of determining the economic fan power or chimney height are described and illustrated by worked examples. With the aid of the design chart, economic mechanical- and natural-draught tower designs can be prepared very quickly. For those film-type packings which do not quite satisfy the general correlation, the design chart may be used in conjunction with two correction factors. For larger departures from the general correlation, such as those to be expected from splash-bar packings, individual design charts can be constructed by the methods described.
    Add to favourites
    Export citations
Discussion on “The economic selection of cooling towers for generating stations” and “The application of friction/heat-transfer correlations to cooling-tower design” before the Supply Section, 5th January, 1955
The authors' replies to the discussion on “The economic selection of cooling towers for generating stations” and “The application of friction/heat-transfer correlations to cooling-tower design” before the Supply Section, 5th January, 1955
Discussion on “Alternating-current-instrument testing equipment”
Problems of hydro-electric design in mixed thermal–hydro-electric systems
  • Author(s): T.G.N. Haldane  and  P.L. Blackstone
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 311 –322
  • DOI:  10.1049/pi-a.1955.0071
  • Type: Article
  • + Show details - Hide details
  • p. 311 –322 (12)
    The paper deals with some of the problems which arise in the planning and development of a system comprising both thermal and hydro-electric plant. In general, when thermal plant predominates it is considered desirable to develop hydro-electric power with the greatest installed capacity the system can absorb in conjunction with the available amount of energy. Practical limitations to low-load-factor operation are discussed. The effects of the introduction of low-load-factor hydro-electric plant on system operation and on the overall fuel consumption of the thermal plants are examined. New circumstances which cannot readily be forecast may later make desirable a change in the design load factor of some of the hydro-electric plants, and the paper stresses the advantage of having, where possible, flexibility in the initial design to enable such changes to be made. Where circumstances permit, consideration of the use of pumps, and especially reversible pump-turbines, is recommended as a means of augmenting storage capacity and either increasing the firm annual load factor or permitting increased installed capacity. The basic economics of the pumped-storage scheme are explained and an example illustrating the flexibility which is possible in planning such an installation is given in the Appendix. The paper discusses the effect on hydro-electric development of the possible ultimate replacement of coal and oil by nuclear fuel in thermal plants, and it is concluded that hydro-electric plant is likely to continue to be advantageous for peak-load operation and that there is no justification for any postponement of long-term investment in hydroelectric works on account of the advent of nuclear power. The effect of rising prices is also discussed, and a general survey is given of present practice in the design of hydro-electric machines. Transmission practice and problems are briefly reviewed as an integral part of hydro-electric design. In conclusion it is pointed out that differences of opinion between thermal and hydro-electric engineers may arise because of inadequate mutual understanding of the inherent characteristics of the two types of plant and of the problems of combined operation. The design of hydro-electric projects in a mixed system must be based, not only on the hydrographical and civil engineering data, but on a comprehensive study of all the many factors involved.
    Add to favourites
    Export citations
Discussion on “Problems of hydro-electric design in mixed thermal-hydro-electric systems” before the joint meeting of the Institution and the Institution of Civil Engineers, 6th January, 1955
Discussion on “Problems of hydro-electric design in mixed thermal-hydro-electric systems” before the North-Western Supply Group at Manchester, 8th February, 1955
The authors' reply to the discussion on “Problems of hydro-electric design in mixed thermal-hydro-electric systems”
Discussion on “Service experience of the effect of corrosion on steel-cored-aluminium overhead-line conductors”
High-voltage transmission developments in Sweden
Single-phase 50 c/s a.c. traction using a rectifier
  • Author(s): A. Mandl
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 339 –348
  • DOI:  10.1049/pi-a.1955.0077
  • Type: Article
  • + Show details - Hide details
  • p. 339 –348 (10)
    The paper explains some of the problems arising when a traction motor is fed from an a.c. supply through a single-phase rectifier. The output voltage of the rectifier contains an a.c. component (ripple voltage) of twice the line frequency. It is shown how the ripple voltage depends on the commutating reactance of the rectifier circuit for various load conditions. The effect of the a.c. component (ripple current) in the motor current and the effect of the degree of smoothing necessary to reduce this ripple current on the commutation and commutator-bar voltage of the motor and on the waveform of the line current are examined. Methods whereby these effects may be reduced to a permissible value are investigated, and the influence of such modifications on the commutation and transient stability—short-circuits and interruptions—are analysed. Oscillographic and other tests carried out on a few traction motors modified in different ways are shown to confirm the theory developed. In the case of a machine with a solid frame, i.e. without laminated magnetic shunt to the compole circuit, certain d.c. commutating conditions must be fulfilled to ensure acceptable commutation when the motor current contains a ripple component.
    Add to favourites
    Export citations
Distortion of turbo-alternator rotor windings through thermal stress
  • Author(s): D.B. Reay
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 349 –361
  • DOI:  10.1049/pi-a.1955.0078
  • Type: Article
  • + Show details - Hide details
  • p. 349 –361 (13)
    The theory of copper shortening in turbo-alternator rotor windings is extended to take account of recent research on silver-free and silver-bearing coppers. The interaction of the turns of a slot stack operating within the elastic strength of the material is analysed and the results are applied to determine the stress distribution in a large winding of cold-worked silver-bearing copper under various conditions of practical interest. Deformation rates at given temperatures are estimated for such a winding. The basis of evaluation of the stack interface friction coefficients applied in the estimate is indicated.
    Add to favourites
    Export citations
Discussion on “The propagation of surge voltages through high-speed turbo-alternations with single-conductor windings”
Discussion on “The transient behaviour of ladder networks of the type representing transformer and machine windings”
Design, performance and application of miniature circuit-breakers
  • Author(s): H.W. Wolff  and  T.G.F. Atherton
  • Source: Proceedings of the IEE - Part A: Power Engineering, Volume 102, Issue 3, p. 364 –373
  • DOI:  10.1049/pi-a.1955.0081
  • Type: Article
  • + Show details - Hide details
  • p. 364 –373 (10)
    The paper is intended as a critical survey of the technical and economic aspects of miniature circuit-breakers. After some introductory remarks on their place in the field of protective gear, a brief historic outline of their development is given, followed by an analysis of the many requirements to be met, together with a study of the more important design features to be observed concerning contacts, arc-extinguishing devices, mechanism, etc. Special attention is devoted to overloads and short-circuit-protection devices, and the rupturing capacity is reviewed in some detail. The application and economy of these circuit-breakers are discussed on a basis of comparison with other protective gear, and with the practice followed in the United States. In conclusion, some suggestions are made for the future development of miniature circuit-breakers in the belief that they will occupy a place of constantly increasing importance.
    Add to favourites
    Export citations
Discussion on “Design, performance and application of miniature circuit-breakers” before the Utilization Section, 20th January, 1955
Discussion on “Design, performance and application of miniature circuit-breakers” before the North-Western Utilization Group at Manchester, 10th January, 1955
Discussion on “Design, performance and application of miniature circuit-breakers” before the North-Eastern Centre at Newcastle upon Tyne, 24th January, 1955
The authors' reply to the discussions on “Design, performance and application of miniature circuit-breakers”
Discussion on “The logical approach to the problems of space warming by electricity”
The author's reply to the discussion on “The logical approach to the problems of space warming by electricity”
Discussion on “Inherent current, voltage and speed control in dynamo-electric machinery”
The authors' reply to the discussion on “Inherent current, voltage and speed control in dynamo-electric machinery”
Discussion on “The testing and specification of bushings in relation to service conditions”
The authors' reply to the discussion on “The testing and specification of bushings in relation to service conditions”
Discussion on “Telemetering for system operation”
Discussion on “Magnetic measurement of mechanical hardness”
Discussion on “Resistance heating of mild-steel containers at power frequencies”
Discussion on “The Royal Festival Hall: electrical installation”
Leakage flux and surface polarity in iron ring stampings
The tensor equations of electrical machines
Alternating voltage, direct-voltage regulation drop and power factor of convertor stations operating on a.c. systems of finite short-circuit capacity

Most viewed content for this Journal

Article
content/journals/pi-a
Journal
5
Loading

Most cited content for this Journal

We currently have no most cited data available for this content.

Print this page
This is a required field
Please enter a valid email address