Electrical status space for clearing procedures In electrical installations

Maintenance personnel must take the clearing procedures , operating the necessary steps to assure that the system or portion of the system on which they plan to work is in an electrically safe working condition [I]. The accepted, reliable way to provide safety is to de-energize the equipment first, then to connect the equipment to ground so that it cannot be re-energized. If there is no electrical power, there is no risk of electrical injury. Complexity of the electrical system normally determines the level of detail planning required for system clearing procedures. The clearing procedures should be completely written, checked and understood by all persons involved before applying them to any portion of the power distribution system. This paper reviews and enhances a previous paper [Z]. It investigates the basic concepts and definitions to givc prominence to operating bonds and to help the procedureproject. It proposes some simple rules , a graphical representation and an algebraic model of electrical status to execute an autocheck of the clearing procedure. The model allows to memorize visually the logic procedures and to count the necessary locks.