Nominal Power Holdover; Power Interruption Effects - Avaya MCC1 Maintenance Procedures

Maintenance strategy
Power interruptions
If power is interrupted to a DC- or an AC-powered cabinet without optional backup batteries, the effect
depends upon the decay time of the power distribution unit:
• If the interruption period is shorter than the decay time, there is no effect on service, though some
-48V circuits may experience some impact.
• If the decay time is exceeded for an EPN, all service to that port network is dropped, and the EPN
must be reset when power is restored.
• For S8700
to that switch node is dropped.
Single-carrier cabinets that are used as Expansion Port Networks (EPNs) have no battery backup. If
power is interrupted for more than 0.25 seconds, all service is dropped and emergency transfer is invoked
for the EPN.
In the above cases, the cabinet losing power is unable to log any alarms. However, in the case of an EPN
going down while a server remains up, alarms associated with the EPN are reported by the system.

Nominal power holdover

AC-powered multicarrier cabinets are equipped with an internal battery that is powered by its own
charger and 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 every other AC-powered cabinet. 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 cabinet's administration (see
times).
Table 5: Nominal power holdover
Cabinet
administration
a-carrier-only
1
all-carriers
1 The cabinet should be administered to all-carriers only if the EPN maintenance board is a
TN775D V2 or greater. However, since it is possible to administer the cabinet to all-carriers
before there is connectivity to the EPN maintenance board, the administration may be incorrect.
To verify whether your cabinet administration is correct, run test maintenance UU (where UU
is the cabinet number). If it is incorrectly administered to all-carriers, a warning alarm will be
issued and you should re-administer the cabinet to a-carrier-only.

Power interruption effects

Power holdover is controlled by software 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.
30
MC, if the EPN contains a switch node carrier, all service to port networks connected
Control carrier
holdover duration
10 minutes
2 minutes
Table 5, Nominal power holdover, on page 30
Entire cabinet
holdover duration
15 seconds
2 minutes
for duration
Maintenance Procedures
December 2003