Tests of 34.5 kV expulsion fuses at the Los Angeles Department of Water and Power

In the Los Angeles basin, the Department of Water and Power (DWP) of the City of Los Angeles operates a 34.5 kV, three-phase, three-wire, 60-cycle, subtransmission system as a distribution system. Large customer loads are served by nominal 6-percent impedance transformers located on customer property which transform the 34.5 kV volts to the customer utilization voltage. DWP will serve 120/240, 120/208, 277/480, 2400/4160, and 4800 volt services. Transformers are fused using pole-mounted and metal-enclosed cabinet-mounted fuses. Fuses are selected to coordinate with directional overcurrent relays and pilot wire relays at the substations. A switch and fuses are installed adjacent to each customer transformer. In order to characterize the 34.5 kV system parameters which are necessary for proper operation of fuses, the fuse performance and application reevaluation (FUSEPAR) program was conducted during June 1987 and October 1988. The results of the tests are presented