Chapter 4: Fundamentals of Logic

INTRODUCTION   The purpose of these specifications is to assure that all tested electrical equipment and systems supplied by either contractor or owner are operational and within applicable standards and manufacturer’s tolerances and that equipment and systems are installed in accordance with design specifications. The need for acceptance testing of electrical power systems is very clear to those with extensive start-up and/or operating experience. Shipping and installation damage, field and factory wiring errors, manufacturing defects, and systems and components not in accordance with drawings and specifications are some of the many problems that can be detected by appropriate testing. When these defects are found before start-up they can be corrected under warranty and without the safety hazards and possible equipment and consequential damages or loss of use/production that can occur if discovered after startup or energizing. In addition, test results obtained during acceptance testing are invaluable as base reference data for periodic testing which is an essential element of an effective maintenance program. This document lists a majority of the field test available for assessing the suitability for service and reliability of the power distribution system. Certain tests have been assigned an “optional” classification. The following considerations were used in determining the use of the “optional” classification: 1. Did another test listed provide similar information? 2. How did the cost of the test compare to the cost of other tests providing similar information? 3. How commonplace was the test procedure? Is it new technology? While acknowledging the above, it is still necessary to make an informed judgment for each particular system regarding how extensive the testing should be. The approach taken in these specifications is to present a comprehensive series of tests that is applicable to most industrial and larger commercial systems. The guidance of an experienced testing professional should be sought when making decisions such as how extensive testing should be. In smaller systems, some of the tests can be deleted. In other cases, a number of the tests indicated as optional should be performed. As a further note, it is important to follow the recommendations contained in the manufacturer’s instruction manuals. Many of the details of a complete and effective acceptance testing procedure can only be obtained from that source. 

. Introduction This chapter introduces the fundamental concepts of DCS systems. The terms Supervisory Control and Data Acquisition (SCADA), Distributed Control System (DCS), Programmable Logic Controller (PLC), and Smart Instrument are defined and placed in the context used in this manual. The chapter is split into the following sections:  Definitions of the terms SCADA, DCS, PLC and smart instrument  Remote terminal unit (RTU) structure  PLCs used as RTUs  System reliability and availability  Communication architectures and philosophies  Typical considerations in configuration of a master station