Specifications

Issue 6 February 2007 411
Figure 91: DC power-distribution unit (J58890CF-2) (front view))
Ground isolation
Each peripheral device that is connected to a system by the asynchronous (EIA) RS-232
interface requires either a 105C, a 105D, or a 116A isolator interface. The interface isolates
ground between the system and external adjuncts.
The isolator interface sits behind a processor port network (PPN) control carrier or behind an
expansion port network (EPN) expansion control carrier. The isolator interface is installed at the
RS-232 interface between the peripheral equipment and the interface connector.
The following figure shows the power distribution in some MCC1s with small battery, short term
battery holdover. Switch node (SN) carriers require two 649A DC power converters and two
cables.
Circuit
breakers
DC power
distribution
unit
Ring
generator
Te r m in al
block
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