An update of grounding experience

This paper presents an update of history and experience with successful applications of high resistance grounding in continuous process industrial power systems. The primary purpose of moving to high resistance grounding systems was to reduce the number of screwdriver flash hazard accidents caused by personnel inadvertently grounding one of the phases. Ground schemes seem to be as different as there are as many manufacturers. This paper is an attempt to standardize grounding schemes. These high resistance grounding systems are arranged for alarming only. The 600 volt class and 5000 volt class systems have proven reliable with an inherent total system charging current to ground (3I/sub CO/) of about 4 amperes, or less. A new design, complete with a list of equipment, is presented based on actual experience. The paper also provides two interesting and specific experiences with the new systems.<>