Home
>
Journals & magazines
>
Proceedings of the IEE  Part A: Power Engineerin...
>
Volume 103
Issue 11
Proceedings of the IEE  Part A: Power Engineering
Volume 103, Issue 11, October 1956
Volumes & issues:
Volume 103, Issue 11
October 1956
An evaluation of two rapid methods of assessing the thermal resistivity of soil
 Author(s): M.W. Makowski and K. Mochlinski
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 453 –470
 DOI: 10.1049/pia.1956.0123
 Type: Article
 + Show details  Hide details

p.
453
–470
(18)
The paper evaluates two methods recently proposed for the rapid assessment of the thermal resistivity of soil in situ, with special application to the assessment of cable ratings.Brief consideration is given to the factors determining the thermal resistivity of the soil, i.e. its composition, compactness and moisture content, and then to the present standard method of measurement by buried spherical or cylindrical heater.The basis of the socalled transientneedle method is then set out. Theory, errors due to departure from ideal conditions and practical application are considered.A method based on soil sampling is next discussed. After critical considerations of the underlying theoretical and practical work by Gemant, Kersten and Mickley in the United States, a nomogram is introduced by means of which the thermal resistivity of sandclay mixtures of known physical characteristics may be simply determined. The practical application of the two rapid methods to field measurements is described, and results obtained by the various methods are compared.Finally, the new methods are discussed and compared with that using the static buried heater.
Temperature rises in electrical machines as related to the properties of thermal networks
 Author(s): J.J. Bates and A. Tustin
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 471 –482
 DOI: 10.1049/pia.1956.0124
 Type: Article
 + Show details  Hide details

p.
471
–482
(12)
The conditions are reviewed under which an electrical machine may usefully be regarded, for the purpose of relating temperature rises to losses, as a thermal network of lumped conductances and capacitances, having an electrical analogue.Although the thermal resistivities are distributed, it is shown that lumpedresistance networks may be found that reproduce the relationships between the inputs of heat to the parts and the mean temperature rises over the volumes of the parts. Sources of nonlinearity are considered, and it is shown that in many cases a linear model is adequate. The effect of transport of heat by the flow of a cooling medium cannot be introduced into a simple network model. The equations are linear, but do not have the properties of symmetry and reciprocity that are characteristic of static networks. Examples of such equations are given and some comments are made on the general form of the relationship between temperature rises and heat inputs, and the uses of such relationships.Consideration is given to methods of testing to discover the coefficients of such equations, or the constants of an analogous electrical network where this exists, and methods that make use of intermittent loading are described. A novel timing device for use in such testing, a novel slipring contact for use with temperature detectors on rotating parts, and some special features of resistancetype temperature detectors are described.The results of measurements on a 25 h.p. milltype motor are given both for forcedventilated and for totallyenclosed conditions, and the appropriate equations, and where possible the equivalent thermal networks, are deduced. The measurements also include information about the temperature distribution in various parts, both for continuous and for variable loading.One purpose of the work was to provide a basis for a new approach to the problem of the estimation of temperature rises with variable loads and speeds. The groundwork for this is included, but the specific problem is discussed in a separate paper.
Temperature rises in electrical machines on variable load and with variable speed
 Author(s): A. Tustin and J.J. Bates
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 483 –492
 DOI: 10.1049/pia.1956.0125
 Type: Article
 + Show details  Hide details

p.
483
–492
(10)
In selecting an electrical machine it is required to estimate how hot the windings will become when the most onerous duty anticipated is performed. This has been difficult when the duty involved varying loads and speeds. Relationships are given by which such estimates may be based on the results of temperature measurements on a machine of the type in question resulting from sustained operation of the onoff type. The data required to specify the capabilities of a machine can be given by two curves, and so may be included on the data sheet for a machine of given type. No measurement or specification of the energy losses as such is required, the method being essentially a comparison between the set or combination of various operating conditions that constitute the duty, weighted according to the time each condition holds, with measurements for representative operating conditions on the testbed.Methods of carrying out suitable typetests are discussed, and the proposals are illustrated by the results of measurements and calculations on a typical 25 h.p. directcurrent milltype motor, operating both with forced ventilation and totally enclosed.
Performance and heating curves for motors on shortrun duties
 Author(s): A. Tustin ; D.F. Nettell ; R. Solt
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 493 –504
 DOI: 10.1049/pia.1956.0126
 Type: Article
 + Show details  Hide details

p.
493
–504
(12)
The paper shows how curves may be prepared that facilitate the design or selection of motors for services with short runs such as the operation of cranes or urban transport. From these curves, with little calculation, the values of such quantities as mean speed, power consumption and temperature rise of motor when operating on a statistically specified schedule, may be estimated for various combinations of motor windings, gear ratios, accelerating currents and the other quantities open to choice.The procedure is based on the recognition of the conditions under which the characteristic curves of the motor and the speed/time curves in operation are of similar shape. One condition for this is that the magnetization curves of the motors should be of the same shape. For classes of motor and operation satisfying these conditions for similarity, various ‘required’ quantities may be given by single curves with scale factors. It is shown that the curves as drawn (i.e. with scale factors of unity) are the characteristics of a hypothetical sample or ‘model’ of the class of drives. Such models are not necessarily realizable physically.The principles are illustrated by the development of curves giving run times, current consumption, motorheating coefficients and other quantities that result from the operation of serieswound motors having magnetization curves of the shape found to be characteristic for modern milltype motors. The application of these curves is briefly illustrated by consideration of the choice of a motor for a longtravel motion on a crane.The data presented are intended to be illustrative rather than complete and to suggest means by which users and designers may prepare data adapted to their particular needs and to the particular classes of motor in question.
Discussion on “Temperature rises in electrical machines as related to the properties of thermal networks”, “Temperature rises in electrical machines on variable load and with variable speed” and “Performance and heating curves for motors on shortrun duties” before the Utilization Section, 19th April, 1956
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 504 –506
 DOI: 10.1049/pia.1956.0127
 Type: Article
 + Show details  Hide details

p.
504
–506
(3)
The authors' replies to the discussion on “Temperature rises in electrical machines as related to the properties of thermal networks”, “Temperature rises in electrical machines on variable load and with variable speed” and “Performance and heating curves for motors on shortrun duties”
 Author(s): A. Tustin ; J.J. Bates ; D.F. Nettell ; R. Solt
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 506 –507
 DOI: 10.1049/pia.1956.0128
 Type: Article
 + Show details  Hide details

p.
506
–507
(2)
Discussion on “Equipment of instrumental accuracy for recording and reproduction of electrical signals, using cinematographic film” before the NorthEastern Radio and Measurements Group, at Newcastle upon Tyne, 19th March, 1956
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, page: 508 –508
 DOI: 10.1049/pia.1956.0129
 Type: Article
 + Show details  Hide details

p.
508
(1)
A dualcomparator mhotype distance relay utilizing transistors
 Author(s): Colin Adamson and L.M. Wedepohl
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 509 –517
 DOI: 10.1049/pia.1956.0130
 Type: Article
 + Show details  Hide details

p.
509
–517
(9)
The paper describes further work on a mhotype relay using transistors, which depends for its operation on direct phasecomparison. The relay is rendered free from transient overreach by the use of a dual comparator circuit configuration. Relay accuracy is discussed and the methods which have been employed to improve the accuracy of the relay during operation without increasing its sensitivity are described.The tests applied to the relay and the reasons for their adoption are given briefly. Accuracy/range charts and dynamic mhocurves are presented for the relay connected as a phasefault element with normal polarization, with polarization from an unfaulted phase and with the use of memory.It is concluded that the relay is a marked improvement over prototypes described earlier by the authors, particularly in respect of accuracy and absence of transient overreach. Speed of operation is discussed, with particular regard to the use of an alternative criterion of operation in which only one of the two comparators must detect a fault before a tripping signal is produced.Probable improvements in the relay design with a view to economy in the number of transistors are considered. No transistor failures have been experienced.
Discussion on “Flat pressure cable” before the South Midland Supply and Utilization Group, at Birmingham, 13th February, 1956
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 517 –518
 DOI: 10.1049/pia.1956.0131
 Type: Article
 + Show details  Hide details

p.
517
–518
(2)
A novel highvoltage peak voltmeter
 Author(s): W.P. Baker
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 519 –522
 DOI: 10.1049/pia.1956.0132
 Type: Article
 + Show details  Hide details

p.
519
–522
(4)
The paper describes a new type of highvoltage peak voltmeter which is free from the errors normally encountered in such instruments. The instrument, which includes rectifiers in a feedback loop, is sensibly independent of rectifier characteristics, and is particularly suited to the measurement of high voltage in the presence of corona discharge.
Discussion on “The supply of electricity in the London area”
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 523 –529
 DOI: 10.1049/pia.1956.0133
 Type: Article
 + Show details  Hide details

p.
523
–529
(7)
Discussion on “Problems of hydroelectric design in mixed thermalhydroelectric systems”
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 530 –532
 DOI: 10.1049/pia.1956.0134
 Type: Article
 + Show details  Hide details

p.
530
–532
(3)
Discussion on “Germanium and silicon power rectifiers”
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 533 –536
 DOI: 10.1049/pia.1956.0135
 Type: Article
 + Show details  Hide details

p.
533
–536
(4)
Discussion on “The installation of metalsheathed cables on spaced supports”
 Source: Proceedings of the IEE  Part A: Power Engineering, Volume 103, Issue 11, p. 537 –540
 DOI: 10.1049/pia.1956.0136
 Type: Article
 + Show details  Hide details

p.
537
–540
(4)
Most viewed content for this Journal
Article
content/journals/pia
Journal
5
Most cited content for this Journal

Development and design of spherical induction motors
 Author(s): F.C. Williams ; E.R. Laithwaite ; J.F. Eastham
 Type: Article

Eddy currents and wall losses in screenedrotor induction motors
 Author(s): R.L. Russell and K.H. Norsworthy
 Type: Article

Insulation properties of compressed electronegative gases
 Author(s): P.R. Howard
 Type: Article

A method of measuring selfinductances applicable to large electrical machines
 Author(s): J.C. Prescott and A.K. ElKharashi
 Type: Article

Inductionmotor speedchanging by poleamplitude modulation
 Author(s): G.H. Rawcliffe ; R.F. Burbidge ; W. Fong
 Type: Article