Electrical Engineers, Proceedings of the Institution of

The loop or ring-type data networks using full duplex-communication links between the nodes have been investigated. The results presented in the paper concern two specific modes for handling the messages. These are termed `store and forward¿ and `check and forward¿. Both modes have been analysed using extensions of the single-server queueing theory and also simulated extensively using GPSS softw... View full abstract»

Network analysis, in terms of S-parameters, is invariably carried out in modern textbooks by employing the power-wave concept. It is shown that this approach is not relevant to practical measurement; furthermore, the complication of square roots, real parts, conjugates, moduli and conjugate transpose matrices is carried throughout the mathematics. These difficulties are overcome by employing the v... View full abstract»

A rigorous analysis is carried out of a typical dual-directional coupler network analyser to demonstrate the application of a new circuit analysis technique based on the principle of matrix renormalisation, described in a companion paper, to cascaded multiport networks. The manner in which previously published calibration equations were derived is explained in detail. The analysis is carried out e... View full abstract»

A new form of inverter-fed brushless synchronous motor is described, having a cylindrical rotor with internal flux barriers and a 3-phase rotor winding connected to two diodes. An improved analysis and calculation method is presented for this and related types of machine. Very good synchronous performance and correlation with theoretical predictions are demonstrated by practical tests. View full abstract»

Numerical solutions are presented for temperature distributions in the coils of a disc-type transformer winding. The numerical method was applied to plane coils corresponding to those used in a full-scale model of an oil-cooled disc-type transformer winding. The agreement between theoretical and experimental results was found to be very good. View full abstract»

The paper details a method by which the equations describing a 3-phase synchronous machine may be transformed into the frequency domain to provide a means of digitally simulating faults at the generator terminals. Evaluation of the Fourier integrals involved in determining the machine response is achieved by means of the fast-Fourier-transform algorithm, and numerical results are presented togethe... View full abstract»

Three methods of transient analysis of a d.c. separately excited motor, controlled by a chopper with square-wave output voltage, are derived. These methods are compared with regard to accuracy and usefulness. The methods require much less computation time than necessary for a step-by-step solution of the system differential equations, and, in some cases, can be used for deriving a transfer functio... View full abstract»

With the replacement of steam locomotives by diesel and electric tractors, it was natural to look to electrical energy as a heat source for passenger trains. When substantial parts of the main lines were electrified at 25 kV, the opportunity to change from steam heating to electric heating was taken. To maintain compatibility between electric and diesel locomotives some of the latter were required... View full abstract»

The large number of published circuits for forced commutation inverters has created a selection problem for the user and designer. The cost of commutation components, with reference to rating, is often disregarded when selecting a particular circuit. The efficiency of the commutation circuit and its effect on the efficiency of the main circuit, is also often disregarded. The paper compares on a pe... View full abstract»

The decomposition of the constrained allocation problem for active power generation is considered, and a problem formulation developed which enables the grouping of the constraints to form a structure suitable for linear decomposition. Dantzig and Wolfe showed that a finite convergence algorithm is a suitable solution of the decomposed primal problem in which a series of linear, constrained subpro... View full abstract»

A bang-bang control scheme to improve system recovery after large disturbances is derived from a linear-system model. Consideration is given to the practical constraints imposed on the state and control variables of a typical power plant. The implementation of the method is carried out on a laboratory micromachine working online with a digital PDP 8 computer. Results are favourably compared to tho... View full abstract»

A method of characterising distributed-parameter systems using lumped discrete models is proposed. These models are classified as parallel and cascade, and they are based on spatial and temporal pulse responses derived from the Green's function associated with the boundary conditions of the system. A technique for representing such models using difference equations in space and time is given and p... View full abstract»

Measurements have been made of time-dependent saturation ion currents flowing to a probe and to the discharge electrodes following the forced extinction of high-current (1¿5 kA) vacuum arcs of short duration (¿1 ms) on copper electrodes. The results have been utilised to derive ion-flux distributions irrespective of ion-charge number, assuming collisionless plasma expansion from the cathode spot... View full abstract»

Static arcs of durations between 3.8ns and 40 ¿s have been initiated, in atmospheric-pressure air, on copper cathodes with an oxide film 100nm thick. By using a scanning electron microscope, the number and size of craters left by emitting sites and the total surface area (containing all of these many craters), from which the oxide had been stripped away, have been measured as a function of arc cu... View full abstract»

The 2-dimensional electric fields internal to five different corner configurations made from three conductors are investigated. These corners are such that the sections in the plane considered consist of two semi-infinite straight lines at right angles joined by a conductor which is part of a circular arc. By methods involving conformal transformations, complex inversion and elliptic integrals, ex... View full abstract»

The need for reduction in wayleave requirements for cables for undergrounding of CEGB 400 kV very-heavy-duty lines has led to the development of the integral pipe-cooled cable system. The thermal design of the system is described and the various practical problems, pertaining to the installation of larger 400 kV cables in pipes, are outlined. Two field-trial installations have been constructed, th... View full abstract»

The movement of cables in integral-pipe water-cooled systems, owing to the thermal expansion which occurs under load, has been studied theoretically. The axial thrust on the anchor joints and the strain variations in the cable sheath have been calculated for certain assumed cable configurations; e.g. the cable may be assumed to take up a helical configuration or to `snake¿ sinusoidally along the ... View full abstract»

The paper describes the reasons for the construction of a cable tunnel under the Rivers Severn and Wye, and the application of an integrally cooled pipe-type cable system to the crossing. Difficulties of applying, to the tunnel scheme, the results of a field trial involving a buried pipe/cable scheme are examined, and the solutions described. The final design of cable and cooling system is given w... View full abstract»

The paper describes the considerations underlying the development of 400 kV internally oil-cooled cable systems, on both theoretical and practical grounds, with particular reference to coolant selection and duct diameters, cooled-section length and critical areas for development. Various conductor designs are described and their merits, leading to the adoption of two cable designs using copper and... View full abstract»

An account is given of two cable trials successfully completed at West Thurrock, which have proved the basis for the design of an internally oil-cooled underground cable system utilising one cable per phase, and capable of matching the rating of a 400 kV 4 × 400 mm2 overhead line. The design and construction of the aluminium and copper conductor cables, stop joints, sealing ends, straight joints ... View full abstract»