Technical and economic aspects when using both DC (-48 V) and AC (230 V) telecom systems

The fast-growing development of the telecom industry generates an increasing need to provide both DC and AC reserve power systems in the same telecom power plant. This need arises from the widespread use of computer-like equipment to perform functions such as traffic measurements, dynamic routing control, billing, surveillance, control and maintenance. The ability to perform these functions remotely from a central location is particularly important as the number of nodes in the telecom network grows to provide enhanced and new services. The focus in this paper is how the AC part can be provided, as the traditional DC power plant is already well documented in this forum. The paper makes comparisons between three power system architectures. The discussion includes reliability considerations, methods to achieve redundancy, maintenance aspects of service and operation, methods of charging and maintaining batteries and means to determine battery condition and predict capacity. It also describes conditions that must be taken into consideration when selecting telecommunication power system architectures.