Powering choices for emerging networks a systems engineering perspective

The powering voltage and frequency used in hybrid optical fiber-coaxial telecommunication networks impacts to different degrees on system efficiency, safety, reliability and response to parasitic currents. Power selection is consequently a system issue and cannot be based on any one factor. This paper examines the relationships between telecommunication network performance and powering parameters. DC powering is eliminated from contention because of the potential for catastrophic corrosion in buried plant. 60 Hz powering provides the longest plant life with respect to corrosion. However, it is less efficient and less safe than low frequency powering. Low frequency power is also considerably less susceptible to the influence of longitudinal sheath current, the fraction of the AC neutral return current flowing on the cable shield in the presence of shared grounds. A 50 V/sub peak/ sinusoidal 60 Hz utility voltage changes the network RMS voltage by only 6% for 1 Hz powering but changes it by 33% when powering is implemented with 60 Hz. It is concluded that the advantages offered by low frequency powering outweigh those of 60 Hz, especially when sheath current is considered.