Circuit Packs and Power
555-233-123
2-2 Issue 4 May 2002
Power
There are two basic powering options available with the DEFINITY Server SI.
These options include AC and DC. The cabinets and their associated power
supplies can be powered by 120/208 volts AC either directly or from a Universal
Power Supply (UPS) system. Alternatively, the cabinets and their power supplies
may be powered by -48 volts DC from a battery power plant.
Each control cabinet in an AC-powered system has an internal battery that
provides a short term holdover to protect the system against short power
interruptions. This method is known as the Nominal Power Holdover Strategy. The
battery is connected so that it automatically provides power if the AC service fails.
The time and extent of the holdover varies according to the type of cabinet and to
whether or not the system has a duplicated control complex.
Table 2-1 summarizes the response to the interruption of power service in
systems without an internal holdover battery.
The next two tables indicate various responses to the interruption of power
service in DEFINITY Servers equipped with an internal holdover battery.
Table 2-2 on page 2-3 provides a summary of holdover times. Table 2-3 on page
2-3 indicates the types of cabinet power interruption based on power holdover
durations.
Table 2-1. Response to Power Service Interruption (without Internal Holdover
Battery)
Cabinet Power
Interruption
Less Than Power
Supply Decay
Greater Than Power
Supply Decay
-48 volt DC external power or
multicarrier cabinet with UPS,
no internal battery.
None on system, some
impact on 48-volt
powered circuits.
All calls dropped, system
reloads.
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