Tracking Faults—You're Grounded

Ground faults can be caused by the simplest human error—dropping a screwdriver on a live conductor, for example. High resistance grounding (HRG) offers one option for tracking ground faults and ensuring that they do not trip breakers, damage equipment or interrupt the load.

HRG has been used for more than 20 years. Permitted by the National Electrical Code (NEC 250-36), it has been used by the petrochemical, paper and food processing industries for many years; now even Internet service providers and telecommunications companies consider HRG an essential part of their power system. What is new is that a digital HRG system is available, with expanded possibilities for data logging and trouble shooting.

Thus, when Appleton Paper upgraded its critical load substation equipment at its plant in West Carrollton, Ohio, HRG was considered a necessary part of the equation. Appleton had already converted a number of solidly grounded 480-volt systems to HRG. Equipment in its wastewater treatment plant, considered critical to the facility's operation, was retrofitted with an HRG system two years ago—and with gratifying results. John Rau, senior power systems engineer, comments that "without HRG, there was a greater risk to personnel and the risk of unwanted downtime."

But for this application, however, Appleton wanted more from its system. Analog high resistance grounding equipment had proven to be an effective safeguard for guaranteeing continuous power, but company officials learned that even more useful information could be provided by digital HRG equipment.

For more information on digital HRG systems from Post Glover, circle 452 on the Reader Service Card.

From Pure Power, Spring 2002.