Protective relay

Abstract: In the control and protective circuits of complex electrical systems it is frequently necessary to make intricate interconnections of relay contacts and switches Examples of these circuits occur in automatic telephone exchanges, industrial motor-control equipment, and in almost any circuits designed to perform complex operations automatically In this article a mathematical analysis of certain of the properties of such networks will be made Particular attention will be given to the problem of network synthesis Given certain characteristics, it is required to find a circuit incorporating these characteristics The solution of this type of problem is not unique and methods of finding those particular circuits requiring the least number of relay contacts and switch blades will be studied Methods will also be described for finding any number of circuits equivalent to a given circuit in all operating characteristics It will be shown that several of the well-known theorems on impedance networks have roughly analogous theorems in relay circuits Notable among these are the delta-wye (δ-Y) and star-mesh transformations, and the duality theorem

Abstract: With the advent of Substation Computer Systems dedicated to protection, control and data logging functions in a Substation, it becomes possible to develop new applications which can utilize the processing power available within the substation. The microcomputer based Symmetrical Component Distance Relay (SCDR) described in the references cited at the end of this paper possesses certain characteristics which facilitate real-time monitoring of positive sequence voltage phasor at the local power system bus. With a regression analysis the frequency and rate-of-change of frequency at the bus can also be determined from the positive sequence voltage phase angle. This paper describes the theoretical basis of these computations and describes results of experiments performed in the AEP power system simulation laboratory. Plans for future field tests on the AEP system are also outlined.

Abstract: Prefaces Introduction and General Philosophies Fundamental Units: Per Unit and Percent Values Phasors and Polarity Symmetrical Components: A Review Relay Input Sources Protection Fundamentals and Basic Design Principles System-Grounding Principles Generator Protection/Intertie Protection for Distributed Generation Transformer, Reactor, and Shunt Capacitor Protection Bus Protection Motor Protection Line Protection Pilot Protection Stability, Reclosing, Load Shedding, and Trip Circuit Design Microprocessor Applications and Substation Automation Problems Index

Abstract: An investigation is made of relays whose reliability can be described in simple terms by means of probabilities. It is shown that by using a sufficiently large number of these relays in the proper manner, circuits can be built which are arbitrarily reliable, regardless of how unreliable the original relays are. Various properties of these circuits are elucidated.

Abstract: Introduction and general philosophies technical tools of the relay engineer phasors, polarity, and symmetrical components basic relay units protection against transients and surges instrument transformers in relaying microprocessor relaying fundamentals system grounding and protective relaying generator protection motor protection transformer and reactor protection station-bus protection line and circuit protection back-up protection system stability and out-of-step relaying reclosing and synchronizing load-shedding and frequency relaying.