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A solid state point on a wave switch has been developed using thyristors to control reactive loads. Completely transistorized control circuitry has been designed for this purpose with provision for one shot or repetitive action. Sequential closing of independent poles is also possible.
A reliable and high-speed point on a wave switch has interesting applications in a 'dynamic test bench' for protective gear testing (Hamilton and Ellis 1956) and in the study of transients in electric machines (Simpson and Slater 1967). Interest is mainly focused on recording the transient behaviour because it simplifies and allows systematic study. The conventional procedure for such requirement has been to use a thyratron relay circuit with momentum transfer device to eliminate contact bounce. Simpson and Slater (1967) utilised a two-pole unit employing power diodes and thyristors. The present work discusses a simpler method of achieving a point on a wave switch. The control circuitry has been designed to suit one-shot or repetitive operation. Provisions are made for sequential closing of a 3-pole unit. [ABSTRACT FROM AUTHOR]

A fast response phase angle measuring device which measures the phase angle twice in the cycle has been developed. The output is obtained just after completion of phase measurement with pre-cycle memory until that instant. Full-scale adjustments are possible for smaller angular variations. [ABSTRACT FROM AUTHOR]

The use of dual comparators for offsetting the transient overreach effects of distance relays is quite popular. Two schemes of static dual comparators, involving powerful and versatile digital and analog techniques, are developed and tested. The introduction of those circuits may help to achieve the more stringent requirements for protection of modern interconnected power systems.
(1) The presence of transients in one or both of the inputs V and V to the coincidence circuits is dependent on the type of measuring circuit used to get the desired distance characteristic. The relay performance is not influenced by transients in any case.
(2) The time of operation of the relay is dependent on several factors and it will be 1 to 3 cycles for most of the power system faults. Actual tests have not been carried out since it is felt that several test results reported on similar comparators will also hold good in this case.
(3) Although the above schemes utilize established criterion of dual comparison an attempt has been made to provide alternative approaches in circuitry with an eye on economy considerations. This paper also introduces to the static relay field the more powerful and versatile digital and analog techniques which may remove several simultaneous switching problems encountered in switched distance and multi-zone schemes. [ABSTRACT FROM AUTHOR]