DC Power Distribution and Grounding in the 5ESSTM Switch

This paper describes the 48-volt dc power distribution system for the 5ESS^TM digital switching system. This distribution system includes duplicate feeder lines for increased system reliability. Each of the feeders serves half of the Power Control and Distribution Frame (PCDF). The PCDF incorporates fuses to protect the load from voltage transients and a capacitor to limit the transients generated during fuse clearing. The 5ESS switching system has a single point grounding system ("ground window"). This method of grounding is found to be the most ideal for controlling the external fault or lightning currents to which the switching system is exposed.