## Power apparatus and electric machines

### More general concepts than this:

### More specific concepts than this:

- Sort by:
- Newest first
- Titles A to Z

### Filter by subject:

- Electrical and electronic engineering [69]
- Power systems and applications [69]
- Power apparatus and electric machines [69]
- a.c. machines [24]
- Computer and control engineering [21]
- Control technology [18]
- Systems and control theory [14]
- Control theory [13]
- Asynchronous machines [10]
- Power convertors and power supplies to apparatus [10]
- [9]
- http://iet.metastore.ingenta.com/content/subject/c3100,http://iet.metastore.ingenta.com/content/subject/b8310d,http://iet.metastore.ingenta.com/content/subject/c3200,http://iet.metastore.ingenta.com/content/subject/b8350,http://iet.metastore.ingenta.com/content/subject/c3260,http://iet.metastore.ingenta.com/content/subject/c3300,http://iet.metastore.ingenta.com/content/subject/c3340,http://iet.metastore.ingenta.com/content/subject/c3340h,http://iet.metastore.ingenta.com/content/subject/b1000,http://iet.metastore.ingenta.com/content/subject/c3110,http://iet.metastore.ingenta.com/content/subject/b1200,http://iet.metastore.ingenta.com/content/subject/b1210,http://iet.metastore.ingenta.com/content/subject/b8370,http://iet.metastore.ingenta.com/content/subject/c3110b,http://iet.metastore.ingenta.com/content/subject/b7000,http://iet.metastore.ingenta.com/content/subject/c1310,http://iet.metastore.ingenta.com/content/subject/c1340,http://iet.metastore.ingenta.com/content/subject/c3120,http://iet.metastore.ingenta.com/content/subject/c3260b,http://iet.metastore.ingenta.com/content/subject/b1100,http://iet.metastore.ingenta.com/content/subject/b7300,http://iet.metastore.ingenta.com/content/subject/c1330,http://iet.metastore.ingenta.com/content/subject/c1340k,http://iet.metastore.ingenta.com/content/subject/c3110g,http://iet.metastore.ingenta.com/content/subject/a,http://iet.metastore.ingenta.com/content/subject/a7000,http://iet.metastore.ingenta.com/content/subject/a7200,http://iet.metastore.ingenta.com/content/subject/a7400,http://iet.metastore.ingenta.com/content/subject/b2000,http://iet.metastore.ingenta.com/content/subject/b2500,http://iet.metastore.ingenta.com/content/subject/b2560,http://iet.metastore.ingenta.com/content/subject/b2560r,http://iet.metastore.ingenta.com/content/subject/b3000,http://iet.metastore.ingenta.com/content/subject/b3200,http://iet.metastore.ingenta.com/content/subject/b7200,http://iet.metastore.ingenta.com/content/subject/b7210,http://iet.metastore.ingenta.com/content/subject/b7320,http://iet.metastore.ingenta.com/content/subject/b7320e,http://iet.metastore.ingenta.com/content/subject/b8320,http://iet.metastore.ingenta.com/content/subject/c1200,http://iet.metastore.ingenta.com/content/subject/c1220,http://iet.metastore.ingenta.com/content/subject/c1340b,http://iet.metastore.ingenta.com/content/subject/c3120c,http://iet.metastore.ingenta.com/content/subject/c3120e,http://iet.metastore.ingenta.com/content/subject/c3120t,http://iet.metastore.ingenta.com/content/subject/c3240,http://iet.metastore.ingenta.com/content/subject/c5000,http://iet.metastore.ingenta.com/content/subject/c5400,http://iet.metastore.ingenta.com/content/subject/c7000,http://iet.metastore.ingenta.com/content/subject/c7400
- c3100,b8310d,c3200,b8350,c3260,c3300,c3340,c3340h,b1000,c3110,b1200,b1210,b8370,c3110b,b7000,c1310,c1340,c3120,c3260b,b1100,b7300,c1330,c1340k,c3110g,a,a7000,a7200,a7400,b2000,b2500,b2560,b2560r,b3000,b3200,b7200,b7210,b7320,b7320e,b8320,c1200,c1220,c1340b,c3120c,c3120e,c3120t,c3240,c5000,c5400,c7000,c7400
- [9],[8],[8],[7],[7],[7],[7],[7],[6],[6],[4],[4],[4],[4],[3],[3],[3],[3],[3],[2],[2],[2],[2],[2],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1],[1]
- /search/morefacet;jsessionid=1prd6bbbt43q8.x-iet-live-01
- /content/searchconcept;jsessionid=1prd6bbbt43q8.x-iet-live-01?option1=pub_concept&facetOptions=2+3&option2=pub_year_facet&sortField=prism_publicationDate&pageSize=20&sortDescending=true&facetNames=pub_year_facet+pub_concept_facet&value1=b8300&operator2=AND&value2=1967&operator3=AND&option3=pub_concept_facet&value3=
- See more See less

### Filter by content type:

### Filter by publication date:

- 1967 [69]

### Filter by author:

- B.J. Chalmers [4]
- F. Fallside [3]
- I.R. Smith [3]
- W. Fong [3]
- A.T. Wortley [2]
- B.J. Kabriel [2]
- B.M. Bird [2]
- J. Reeve [2]
- J.H. Walker [2]
- M.L. Fryett [2]
- P.J. Lawrenson [2]
- R.D. Slater [2]
- R.F. Burbidge [2]
- A. Armstrong [1]
- A. Kazi [1]
- A.J. Haselfoot [1]
- A.R.W. Broadway [1]
- B. Ramaswami [1]
- B.H. Smith [1]
- B.J. Bennington [1]
- B.R. Sarkar [1]
- B.V. Jayawant [1]
- C. Ridgers [1]
- D.N. MacLennan [1]
- D.P. Rea [1]
- D.P. Sen Gupta [1]
- D.R. Wilson [1]
- Dan Teodorescu [1]
- E.E. Ward [1]
- E.J. Davies [1]
- E.M. Freeman [1]
- E.R. Lwithwaite [1]
- E.S. Ip [1]
- E.T. Norris [1]
- G.H. Rawcliffe [1]
- I.F. Carmichael [1]
- I.M. Edwards [1]
- J. Greig [1]
- J. Richardson [1]
- J. Waddington [1]
- J. Štěpina [1]
- J.C. Dunfield [1]
- J.C. West [1]
- J.D. Ainsworth [1]
- J.D. Pearson [1]
- J.F. Marsh [1]
- J.M. Heaton [1]
- J.M. Raven [1]
- J.P. Bickford [1]
- J.R. Reed [1]
- J.W. Lynn [1]
- K. McCloy [1]
- K.C. Mukherji [1]
- K.C. Parton [1]
- K.H. Low [1]
- L.L. Freris [1]
- M.C. Ralph [1]
- M.J. Battisson [1]
- M.R. Harris [1]
- M.S. Garrido [1]
- N. Christofides [1]
- N. Mullineux [1]
- N.N. Hancock [1]
- N.V. Balasubramanian [1]
- P. Reece [1]
- P. Sasidhara Rao [1]
- P.H. Borcherds [1]
- P.O. Carden [1]
- P.R. McLellan [1]
- P.S. Doepel [1]
- R. Farkaš [1]
- R. Hawley [1]
- R. Sreedharan [1]
- R.F. Sims [1]
- R.J. Bland [1]
- R.K. Lay [1]
- R.L. Stoll [1]
- R.L.A. McKenzie [1]
- R.R.S. Simpson [1]
- S. Neville [1]
- S. Reich [1]
- S. Sriharan [1]
- S.A. Nasar [1]
- S.K. Gupta [1]
- S.K. Tso [1]
- Sylvia J. Day [1]
- T.H. Barton [1]
- T.N. Saha [1]
- V. Raytchev [1]
- V.A. Stroev [1]
- W.C. Beattie [1]
- W.D. Humpage [1]
- W.F. Ma [1]
- W.S. Leung [1]
- W.S. Wood [1]
- See more See less

### Filter by access type:

A direct and reasonably accurate method of obtaining an electrical signal proportional to the angular acceleration is of immense interest in the design of feedback control systems. The 2-phase drag-cup motor is widely used as an angular accelerometer. In this letter we propose a new method of determining the electrical parameters of a 2-phase drag-cup accelerometer and show that our method is superior to an earlier method.

It is shown that the logic state of valve currents within an h.v. d.c. convertor can be processed to provide discrete and unambiguous indication of convertor faults. A scheme consisting of the interconnection of a number of identical logic computing elements is described and is shown to have a high ‘fail-safe’ potentiality. The method is based on a generalised table of valve-current states derived in a companion paper.

The behaviour of the currents in valves in a 3-phase full-wave bridge convertor follows a sequential pattern which can be represented as a sequence of ON/OFF operations analogous to binary logic in digital computers. A generalised table is derived which specifies the conducting sequences for any possible mode of operation of a convertor, including fault conditions and subsequent recovery periods where appropriate. The combinations are related to time zones bounded by reference grid pulses and voltage zeros in the a.c.-supply waveform.

The paper discusses the operation of a phase-controlled cycloconvertor such as may be used for a.c.-drive applications. The output-voltage functions obtained using different combinations of control and modulating signals are deduced. An assessment is made of the factors affecting the magnitude of circulating current which can flow in this type of convertor, while as an alternative approach the logical conditions necessary for operation without circulating current are formulated. It is concluded that, although circulating current can be limited by building appropriate reactance into a convertor, the magnitudes involved imply that its prevention by logical control is to be preferred.

The paper describes the use of electrolytic-tank techniques for an initial determination of the electric fields in transformer-bushing insulators. The compound dielectric in the bushing is simulated by means of an electrolytic-tank model having watertight compartments each holding an electrolyte whose conductivity corresponds to the permittivity of the dielectric material. For this purpose, an interface boundary consisting of individual loops of fine copper wire was developed to conduct the electric current from one compartment to another. A 12ft-long electrolytic-tank rig was specially built to accommodate a full-scale bushing model. Various design configurations were investigated, and it was shown that, for example, for a 400kV bushing, the desired performance improvement could be achieved by inserting low-permittivity sleeves in the oil channel.

Synchronous torques occurring in squirrel-cage induction motors may be due to a variety of causes, one of which is the interaction between pairs of stator and rotor harmonics. The paper includes an analytical treatment of the squirrel-cage rotor and applies this and the analysis of the doubly-fed cascade machine to the calculation of synchronous torques of this particular character. The concepts are extended to take account of the way in which a squirrel-cage rotor may provide coupling between stator harmonics of different orders during normal asynchronous operation of the machine, and an equivalent circuit for this is presented.

An alternative method of operation for the well known moving-coil voltage regulator is discussed, and its theory is treated on classical lines. In the new régime, the short-circuited coil is fixed, and the output is drawn from the moving coil, instead of vice versa. A comparison is drawn between this moving-secondary regulator, the moving-coil regulator and the induction-type voltage regulator, which serves to clarify certain basic points in transformer theory. Tests were made on a small laboratory regulator, specially devised for experimental purposes, and some discussion of these tests is included. The same regulator also enables a variety of other educational tests to be performed, the regulator being, in effect, a generalised transformer.

This paper shows how asynchronous operation of a reluctance motor may be obtained by taking advantage of one of the properties of a series *LCR*circuit, in which the inductance is a function of current. Parametric variation of the machine inductance is accomplished by variation of the rotor iron-circuit reluctance, instead of the more conventional change in air gap. These changes in reluctance are utilised in such a way that the circuit alternates between resonant and nonresonant states, with consequent variation in current amplitude. When the resonant state coincides with a positive rate of change of air-gap inductance with rotor position, and hence the nonresonant state with a negative rate of change, the net average torque developed is positive.The speed/torque characteristics are dependent upon applied voltage, series resistance and series capacitance, as well as the rotor geometry. Thus a simple variable-speed a.c. motor having no windings on the rotor is possible. Maximum average torque obtainable from such a machine at very low speeds is of the same order as that obtainable from the same machine running synchronously.A mathematical model is proposed for the machine, from which expressions for torque in terms of the machine and circuit parameters can be obtained. These lead to an equivalent circuit and the differential equations of motion, which are nonlinear with time-dependent coefficients, so requiring solution by numerical or analogue methods.Assumptions made when setting up the model and in subsequent simplifications have been tested experimentally and the results presented. These suggest that the proposed model will provide at least a qualitative indication of dynamic behaviour.All discussion and analysis applies equally well to linear motion provided the appropriate change is made in the ‘rotor’ geometry.The problems of self starting and line-current fluctuation are briefly discussed, and possible solutions are suggested.

The concept of an equivalent magnetic circuit, analogous to an equivalent electric circuit, in which flux replaces current, m.m.f. replaces e.m.f. and reluctance replaces resistance, is well known and widely used, but the technique is generally restricted to the equivalent of d.c. electric circuits. The paper shows how the technique may be extended to cover a.c. electromagnetic systems, using the concepts of quadrature impedance and mutual inductance in the magnetic case. It is shown that the use of an equivalent magnetic circuit is to be preferred for problems in which more than one magnetic circuit is linked with an electric circuit.

The problem discussed relates to the calculation of electromagnetic travelling fields in electrical machines. The idealised structure considered comprises a number of laminar regions of infinite extent in the plane of lamination and of arbitrary thickness. Some or all of these regions may be conducting and/or ferromagnetic with constant permeability. The travelling field is produced by an applied current sheet at the interface between two layers, distributed sinusoidally along the plane of lamination and flowing normally to the direction of motion. A convenient reformulation of existing theory is suggested which simplifies calculation. The normal limitations imposed by the amount of algebraic manipulation involved are removed by the use of a transfer matrix. This provides the facility to introduce numerical values directly into the matrix formulation.

A doubly fed cascade-connected machine system may operate either synchronously or asynchronously. The analysis of both modes of operation is considered, and the corresponding equivalent circuits are shown. Use is made of the basic underlying principles of this type of system to develop a practicable stator-fed synchronous machine. The problem of the steady-state stability of this machine is discussed, and simple methods of achieving stable operation are described.

After a brief review of the conflict between increasing unit sizes and transport-weight limitations and the various methods of overcoming this, the paper outlines the design philosophy underlying the principle of subdivision and reassembly on site and discusses the reasons for adopting the particular method described in the paper and applied to a pilot exercise.Vertical subdivision of the complete unit between phases was adopted, and the various problems encountered in the design, construction and assembly are discussed and illustrated with particular reference to the means adopted for ensuring mechanical stability and accurate realignment of the sections.As adequate dryness of the windings during transport and reassembly is essential, the paper describes the methods used for sealing the windings during transport and for creating suitable conditions of atmospheric dryness and cleanliness during reassembly on an open plinth on site. The steps taken were deemed sufficiently safe to obviate the need for special high-voltage tests on the insulation after reassembly, and this judgment was proved to be correct by the successful commissioning of the unit.The principle so successfully demonstrated on a pilot exercise can be applied to much larger units, and it can also be of great value in those countries where the present transport-weight limitations impose severe restrictions on the maximum size of a 3-phase unit that can be installed on certain sites.

There has been considerable progress in substituting aluminium for copper in electrical apparatus such as busbars and transformers, but little or none in rotating electrical machines. Making certain simplifying assumptions, the paper evolves a mathematical analysis for salient-pole generators by which the losses, dimensions and cost of a generator with aluminium windings, with the same rating and short-circuit ratio (s.c.r.) as one with copper windings, can be evaluated. An extension of the analysis permits a price comparison to be made both without and with the capitalisation of losses. These results are displayed as families of curves with either gap diameter, or cost of copper, as the independent variables. An appendix considers the substitution of aluminium for copper in the stator winding only. Worked examples are given of a medium-speed and a low-speed hydroelectric generator, and the results show that, for the medium-speed type to become an economic proposition with aluminium windings, the price of copper must increase by about 20%, whilst for the low-speed type an increase in the price of copper of only about 5% is sufficient. These conclusions may be modified in countries developing their industrial capacity with ample indigenous aluminium, but importing copper. Here the reduction of the drain on foreign credits by restricting the import of copper may be the paramount consideration.

The paper investigates synchronous-machine damping and synchronising torques analytically and experimentally, in two distinct reference frames. The first is that of Park and the second is a freely rotating frame used by Kron, Ku and others. it is found that the uniformly rotating free frame presents a clear picture of the nature of the torque components and the sources of these during hunting conditions. The analysis has been confirmed by tests on a laboratory machine.

Real electrical machines differ from the conventional models of generalised theory primarily in three ways: they are magnetically nonlinear, windings produce m.m.f. harmonics in addition to the fundamental, and air-gap permeance harmonics higher than the second are significant. The practical effects of the latter two complications on terminal characteristics are discussed with particular reference to waveforms in a small but otherwise conventional synchronous machine. Axis transform methods are of little or no value in such situations, and two numerical techniques for direct solution of the machine equations are discussed. A Runge-Kutta computation establishes that high accuracy is obtained by consideration of a modest number of harmonics, so that a highly efficient procedure based on Newton-Raphson reduction is possible. In the case of the popular 3-wire star connection, the equations reduce to essentially the conventional *d*, *q*axis equations plus an additional one giving the neutral potential. On the other hand, the 4-wire star and the mesh connections yield equations not in accord with the *d*, *q* equations, and significant time harmonics can result.