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 c abinets are equipp ed with an internal battery, powered
by its own charger, that p rovides a short term holdov er to protect the system
against brief power interrup tions. This feature, known as the Nominal Power
Holdover, is optional on c abinets supplied by a UPS and required on all other
AC-powered cabin ets. The battery is controlled in suc h a manner that it
automatically provides p ower to the cabinet if the AC servic e fails. The duration
of the holdover varies acc ording to the type of c arrier 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 sof tware in the above manner in order to allow
the system to sustain multiple brief p ower interruptions without exhausting the
batteries before they have time to recharg e. After power is restored, the batteries
are recharged by a c ircuit that monitors current and time. If the batteries take
more than 30 hours to recharge, a minor alarm is r aised, indicating that the
batteries must be replac ed or the charger rep laced.
The 397 Battery Charger Circuit immediately d etects loss of AC power and raise s
a warning alarm against AC-POWER that is not reported to INADS. Certain
maintenance objects suc h 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 effec ts depend up on the
duration of the outage. Battery p ower 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 p eriod, but is restored b efore the
control carrier holdover exp ires, all service is drop ped and emerg ency transfer is
invoked. The SPE is kept up allowing for a speed y restoration of service since a
rebo ot is no t req uired . All non-SPE c irc uit p acks must b e rei nsert ed, t aking abo ut
a minute, depending on the size of the system. If the interruption exc eeds the
control carrier holdover, all servic e 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