New DC Power Supply System

A new DC power supply system is under development. The 150V DC power supply system is suitable for digital telecommunications systems. In the 150V system, since bulk DC-DC converters are necessary to supply 48V power, the bulk converter system configuration was investigated. To meet the overload caused by heavy traffic congestion and to assure higher reliability than conventional power supply systems, it is effective to compose the bulk converter system of n+2 units and to install a 48V bypass feeder from a part of the 150V batteries to 48V loads in case of local exchange bulk converter system. A grounding method for noise suppression in the converter output has also been investigated. It clarified that a one point grounding method should be introduced and the out-put ground terminal for each converter should be grounded with a cable separately from the main distribution cable. The 150V system gives 45% space saving, 35% energy saving and 30% cost reduction for the digital switching system power supply, as compared with a conventional 48V system.