Grounding of D-C structures and enclosures

THE GROUNDING of supporting structures and enclosures for d-c power circuits and apparatus has been a controversial subject ever since metal-enclosed power rectifiers and switch-gear came into use in the electrochemical and other industries. Many users of d-c equipment naturally followed the well-established a-c practice of solidly grounding enclosures through a low-resistance conductor. Relatively few of these equipments included sensitive grounding protective relays. Many cases of serious injury and damage due to ground faults that might have been avoided by the use of grounding protective relays are recorded in an earlier paper.1