DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Architecture
1-27Power Interruptions
1
Nominal Power Holdover
AC-powered multicarrier cabinets are equipped with an internal battery, powered
by its own charger, that provides a short term holdover to protect the system
against brief power interruptions. This feature, known as the Nominal Power
Holdover, is optional on cabinets supplied by a UPS and required on all other
AC-powered cabinets. The battery is controlled in such a manner that it
automatically provides power to the cabinet if the AC service fails. The duration
of the holdover varies according to the type of carrier and whether or not the
system has a duplicated SPE. See Table 1-7
for duration times:
Effects of Power Interruptions
Power holdover is controlled by software in the above manner in order to allow
the system to sustain multiple brief power interruptions without exhausting the
batteries before they have time to recharge. After power is restored, the batteries
are recharged by a circuit that monitors current and time. If the batteries take
more than 30 hours to recharge, a minor alarm is raised, indicating that the
batteries must be replaced or the charger replaced.
The 397 Battery Charger Circuit immediately detects loss of AC power and raises
a warning alarm against AC-POWER that is not reported to INADS. Certain
maintenance objects such as external DS1 timing will report major alarms in this
situation. When power is restored, the AC-POWER alarm is resolved.
PPN Cabinet with Power Holdover
When power is interrupted to a PPN cabinet, the effects depend upon the
duration of the outage. Battery power is supplied to the whole cabinet for 10
seconds. If power is restored during that period, service is not affected. If the
interruption exceeds the cabinet holdover period, but is restored before the
control carrier holdover expires, all service is dropped and emergency transfer is
invoked. The SPE is kept up allowing for a speedy restoration of service since a
reboot is not required. All non-SPE circuit packs must be reinserted, taking about
a minute, depending on the size of the system. If the interruption exceeds the
control carrier holdover, all service is dropped and the system must reboot when
Table 1-7. Nominal Power Holdover
Cabinet Type Control Carrier Entire Cabinet
PPN, duplicated SPE 5 minutes 10 seconds
PPN, simplex SPE 10 minutes 10 seconds
EPN 10 minutes 15 seconds
