The Plug-in Power Supply Card is powered from a -48 Vdc source and provides -24 Vdc power to the 5-card Shelf or the 8-card Shelf. The card has a floating input, and does not ground the station batteries. It also offers the possibility of recharging the Plug-in Battery Backup Card, Model 751312.
If the Plug-in Battery Backup Card is not used, then two Plug-in Power Supply Cards may be installed in the 5- or 8-card Teleline shelf for redundancy.
Each card is capable of providing the power required by a fully loaded shelf. When two cards are available, the load is shared by the two cards. If one of them fails, the other one takes over the full load without interruption of power.