An economical distribution system for high-density commercial and industrial loads

Central business districts (CBDs) of most major cities of the world are supplied by underground medium-voltage radial feeders or networks which are meshed at medium or low voltage. Radial feeders are the simplest and cheapest way of supplying these major commercial loads, but a feeder fault will affect every customer on that feeder. Mesh networks provide a much more reliable and flexible supply, but require large numbers of medium-voltage (MV) or low-voltage (LV) circuit breakers such as network protectors for ease of operation. Using the CBD of South East Queensland, Australia as an example the authors present a more economical network of distribution substations. By minimising the number of circuit breakers and adopting standardised modules leading to standard layout, circuitry and protection designs, it has been possible to significantly reduce the cost of distribution