International Journal of Electrical Engineering & Education

A comparative study of various types of industrial distribution systems is made from reliability considerations. A two-state mathematical model is used for analytical prediction of system reliability. A method is discussed to maximise reliability of industrial distribution system by utilising redundant components. The computational procedure is illustrated by an example.

The work presented here deals with the effects of a simple surge absorber composed of an ordinary choke coil, and connected in series with the line ends of a power transformer. The study includes the effect of such absorbers on the wave form of the incident surge, and consequently on the voltage distribution along the high voltage transformer windings. Moreover, a sample set of calculations has been performed to find out the way, the absorber constants, and the transformer simulating capacitor capacitance, contribute to those effects. These calculations are included in the second part of the work.

The problem of determining the potential distribution across a string of insulators is solved by using the difference equation approach. Explicit expressions for the potentials are given in series as well as closed forms, and their variations with the parameters are displayed in the form of graphs. The results are also applicable to line calculations for major street lighting schemes.

The central problem in teaching large numbers of students is to keep close personal contact between students and staff and also to have an efficient organization. Presented here is one solution to questions of motivation, participation and assessment, but each lecturer should be free to find his own.

A method to determine separate values of primary and secondary leakage reactances of a transformer is given. An experimental determination of input impedance, open circuit time constant and dc resistance of one of the windings of the transformer, yields the required reactances.

The description is sufficient for this device to be constructed. The phasor diagram of the currents and voltages involved in the two-wattmeter are projected; the current phasors can be rotated to correspond to various power factors. Point-by-point consideration clarifies the effect on instrumental readings.

An algorithm closely following Bergeron's method has been developed to calculate transients in a transmission system with step input. The transmission system includes a transmission line, a transformer, a load, and a thyrite arrester. It is shown how an exact solution can be obtained with the help of this algorithm when a resistive non-linearity is presented in the system.

The graphical solutions to some simple impedance networks, including L, T, and π configurations are presented here together with the analytic derivations. These graphs are helpful in visualizing the values of the circuit elements in designing impedance matching networks. Based upon these circuits, the constructions depend primarily on conversions between parallel and series circuits that are accomplished by means of straight lines instead of semi-circles as described previously by McNally and Keen.

It is shown that a liquid—epitaxy system for GaAs is relatively easily set up as a useful means of teaching electronic materials technology. The equipment required, essential aspects of operating such a system, the assessment methods for the single-crystal layers produced and a brief review of the possible new device developments are presented. Some experimental results are given which are obtained by such an educational system.

The paper presents a method of analysis of a solid rotor induction machine, in which both finite stator permeability and finite thickness of current sheet, not considered so far, have been incorporated. To take the finite axial length of the machine into account, a three-dimensional model of a machine is considered and the analysis is made in rectangular co-ordinates. The method, unlike the previous ones, indicates an easier way of studying machine characteristics, even though it is more rigorous in nature.

Use is made of an auxiliary matrix to count trees of complete bipartite graphs. One form of the auxiliary matrix achieves partial diagonalization of the node admittance matrix and a second form of the same matrix completes the enumeration. Extension of the results is shown to be compatible with a known count for trees of complete graphs.

This paper describes the application of quasilinearization algorithm and its various modifications to solve the non-linear optimal control problems in power systems. Results obtained by this indirect numerical technique are compared to those obtained by other, direct methods. It is shown that a proposed hybrid approach, in conjunction with the continuation method, can be considered as an effective iterative procedure for most practical problems in power systems.