E. L. Harder

Computers and automation

IN THE BRIEF SPAN of years since the closing days of World War II, we have witnessed a technological development in computers of such broad proportions that it is still impossible to appraise its far reaching effects adequately. Perhaps, the best way to express the enormous influence of this revolution is simply to point out that practically all of mans actions in producing the necessities and luxuries of life fall into two categories, namely his mental and his physical work. All of his mental work has to do with the processing of information in some form or other, and the close relationship of the computer to the human brain and its functioning needs no elaboration here. It should have been expected that nearly all of the operations of the civilized world, in which the human brain is involved to a greater or lesser extent in carrying out the task, could be aided by a technological development which performs accurately and at high speed, some of the functions of the brain. This is variously called computing, or information- or data-processing. Its field of application is as broad as human knowledge and is far beyond the comprehension of any one individual. However, large teams of scientists and engineers are currently at work in many of these compartmented fields of knowledge, learning how to adapt and develop the automatic processing methods of the computer to the needs of their particular fields.

A New High-Speed Distance-Type Carrier-Pilot Relay System

This paper outlines the reasons for application of pilot relay equipment, particularly of the carrier-current type. A one-cycle carrier-pilot-relay scheme is described which now makes available the desirable high-speed and back-up characteristics of step-type distance protection combined with the 100 per cent simultaneous tripping feature possible with a pilot circuit. Impedance and over current supervised single-phase directional elements are utilized for controlling carrier on phase and ground faults, respectively.

Transmission Line Design and Performance Based on Direct Lightning Strokes

A method for estimating the lightning performance of transmission lines is presented in this article. It is based on the stroke current probability data and takes into account all the line parameters believed to affect the performance materially. The curves cover the complete range of transmission line designs.

Regulation of A-C Generators With Suddenly Applied Loads

DETERMINATION of the voltage drop at the terminals of small generators during the starting of relatively large motors has long been an important problem, particularly in connection with the starting of large motors on power-house auxiliary generators. Interest in this problem has been greatly accentuated by the wartime application of many small a-c generators, in fixed and mobile locations, supplying motors of ratings amounting to an appreciable fraction of the generator rating. It is essential in such applications to be able to predict accurately the maximum voltage drop in order to be sure that motor starters on the line will not drop out and that motors already running will not stall when large additional loads are started. Other types of apparatus are critical to low voltages of short duration, particularly if such low voltages recur frequently.

Linear Couplers for Bus Protection

THE linear coupler transformer is a constant mutual reactance connecting the primary circuit to the relay. It introduces a new principle into the protective relaying art, a principle∗ that is fundamentally sound and that eliminates completely, at its source, the most troublesome problem that has been standing in the way of simple high-speed bus protection. That problem is saturation of the current transformers by the d-c transient current that flows for a number of cycles after the occurrence of a fault. Its solution consists of dispensing with the iron, a solution that appears so obvious on the face of it that it is fair to inquire why it was not adopted years ago. This paper might stop right here were it not for the answer to the last question.

Protection of Pilot-Wire Circuits

THIS paper reviews the problem of protecting pilot-wire circuits, briefly discusses the sources of disturbing voltages, describes two types of neutralizing transformers, and illustrates how they are used to distribute the disturbing voltage most favorably throughout the pilot-wire circuit. The recent increase in use of high-speed pilot-wire relays for the protection of important power circuits has accentuated the need of better understanding of the pilot-wire protection problem. Therefore, a review of this general subject and a description of a new type of neutralizing transformer with mathematical formulas to determine its effectiveness, is considered timely.

Principles and Practices of Relaying in the United States

The rapid growth in power system size and interconnection over the past 30 years has greatly increased the problem of isolating faults. Standards of service have increased, making necessary greater reliability, and higher speed of operation. Innumerable relaying devices and schemes have been developed to meet the more exacting requirements. Some have been designed for special situations and others apply to basic situations which occur on many systems. It is these latter which it is hoped to discuss in this paper.

Static Voltage Regulator for Rototrol Exciter

THE CONCEPT of a generator voltage regulator as an amplifier which produces a large correction in field current for a small departure from normal voltage is quite well known.1 In the conventional regulator, such as a directacting type, this amplification is secured partly in the regulator and partly in the exciter. A rotating amplifier-type regulator provides the amplification almost entirely in the rotating machines. Exciters may be used to obtain twoor more stages of amplification, or a single machine having high amplification such as a Rototrol exciter may be used. An example of two-stage excitation is a system with the regulator working in a pilot exciter field.

Relay Protection of Tapped Transmission Lines

The war, with its attendant shortage of critical materials, has led to a considerable increase in the number of tapped lines. This paper deals with the method of protecting circuits of this kind under the three headings: 1. Pilot-wire protection, a-c and d-c schemes. 2. Carrier-current protection. 3. Other protective schemes. Directional overcurrent or network. Distance type. Three-terminal lines are classified into three types with regard to other system connections between the terminals connected by the line in question. These are further classified as to power sources to aid in analyzing limiting conditions for relay applications. Typical operating characteristics of a-c pilot-wire equipment for three-terminal lines are shown. In general in dealing with pilot-wire, carrier, and other types of protection, those problems peculiar to application on three-terminal lines are analyzed and methods given for solving some of the more troublesome problems.

Transient and Steady-State Performance of Potential Devices

THE increasing use of high-speed relaying with the resulting emphasis on the transient performance of potential devices has led to an extensive analysis of their performance under transient conditions. Both analytical and network-calculator methods have been developed for predetermining transient performance. Tests have been made to substantiate the methods of analysis and to show the character of the transient and extent of control in typical cases. Novel means have, likewise, been devised for presenting the steady-state performance of the device. In particular, the introduction of the equivalent circuit of the device represents an important advance in the visualization, both of the transient and steady-state performance. In this paper, after a brief description of circuit arrangements of the potential devices under discussion, the new theoretical methods are presented, followed by the substantiating test information.