Low Magnitude, Non-Violent, Fault Clearing Devides for Use with Current Limiting Fuses

The use of higher voltages (e.g. 35kV) in underground distribution systems has introduced new problems in control of fault currents. These problems are especially evident in the higher ampacity load current ranges. This problem may be addressed by the use of a low current vacuum interrupter (under 2000 amps) coordinated with a backup current limiting fuse to give full-range fault protection without the operating violence and space requirements of conventional expulsion fuses and at a lower cost than conventional circuit breakers. This approach can provide a full-range, non-violent fault interrupter up through the full-rated load current of present load density requirements.