A new analytical language for clearing procedures in electrical installations

Abstract

"Lockout" and "tagout" procedures to ensure safety is universally accepted. In order to perform operations of electrical maintenance on a zone, portion or components of the system, it is necessary to use more elaborate clearing procedures and written switching instructions for systems, together with a single-line diagram. Past practice has been largely empirical. This paper offers an analytical approach to the problem. Complex power distribution systems may have several operating bonds (interconnections), such as multiple sources and switching devices in each area or zone. They require several operating steps to isolate the safe working zone SWZ. Details of developing and applying lockout/tagout procedures can vary. This paper presents an analytical approach to the planning and control of lockout/tagout procedures. It reviews and enhances previous papers and investigates the basic concepts and definitions to give prominence to operating bonds and to provide alternative, independent lockout/tagout analysis. It proposes some simple rules and bond definitions to facilitate programming. It introduces a "new language", that is a graphical representation, a color convention and a logic code to write and show symbolically the instruction list of electrical status. Together, intuitive and mathematical approaches can heighten understanding. The Parise program allows memorizing visually the logic procedures, counting the necessary locks and executing an auto-check of the clearing procedure. Software programs using a PC, based on the model in this paper, have been developed for aided or interactive training on network samples and for planning new networks. They can facilitate a faster evaluation and an accurate analysis, reducing the risk of error.