USG ARC FLASH STUDY
Krech Ojard conducted a United States Gypsum (USG) arc flash study, short circuit current study, and device rating evaluation be performed at their facility in Cloquet, Minnesota. The arc flash hazard analysis was to be performed from the main service entrance down to the Motor Control Center (MCC) level to establish the Personal Protective Equipment (PPE) required for personnel working on the plant’s electrical system. Krech Ojard & Associates’ (KOA) Electrical Group provided on-site data collection during a weekend shutdown period. Data was gathered to retrieve information on the electrical power system design in preparation for the power system studies needed for the arc flash hazard analysis. Substation switchgear data and electrical protective device ratings and settings were collected along with conductor sizes and lengths down to the MCC and 480V panel level.
The data collected on-site was used to model the USG facility’s electrical power system with SKM Power Tools® software. A short circuit current study and device rating evaluation were performed. The final report listed over-dutied equipment. An arc flash study was performed using IEEE 1584 methods, and PPE requirements were determined based on NFPA 70E categories. Arc flash remediation recommendations were presented in the final report for those areas requiring PPE Category 3 or higher. Coordination studies were performed for electrical protective devices at each of the high PPE category areas.
The short circuit current study results included, USG arc flash study results, coordination study results (including Time vs. Current Curve plots), remediation recommendations, and plant one-line diagram drawings. The arc flash report was presented to USG for their review and comments prior to printing of arc flash hazard warning labels.
