Operation of Weapon System Loads from Rural Power Systems

Problems of operating unattended equipment on rural power systems are considered. Criteria for switching to alternate power sources are developed and appropriate specifications are proposed for the power sensing devices. Emphasis is placed on special fault patterns frequently not detected by simple sensing techniques. Improperly designed or inadequate sensing equipment or circuits will permit faulty commercial power to remain connected to the load equipments, with resultant catastrophic damage. Sophisticated power sensing equipment is required to initiate a transfer from normal to standby and emergency power systems. Power sensing should detect low voltage, unbalanced voltages, reversed phase rotation or loss of neutral. The power transfer system must be designed to prevent contactor chatter or cycling from voltage differentials between drop out and pull-in levels.