A Proposed Standard for the 48-Volt Power Rail

The -48 V power source is emerging as the most widely used system for reserve power and secondary power distribution in telecommunication installations. Over the years, a number of variants of the basic -48 V system have been implemented and used. Compatibility between communication equipment and power equipment, across the globe, at present and in future, can only be ensured by a uniform -48 V power rail. In this report, a set of limit values is proposed for defining the -48 V power system to telecommunication system interface. The essential parameters characterizing the -48 V power supplied to telecommunication equipment and the allowable effects of telecommunication equipment on the -48 V power rail are defined. Rationale and references for the proposed parameter values are given. It is concluded that general acceptance of the proposed standard would enhance engineering, installation, operation, and maintenance of the evolving global communication network.