Nortel Meridian 1 Option 11C Planning And Installation Manual page 19

Reserve power
If the NTAK04 or NTDK78 AC/DC power supply is powered down
while it is operating on DC reserve power from a battery backup unit,
the Option 11C system cannot be powered up again until AC power is
restored. Be careful not to open the circuit breaker, either on the
battery backup unit, or on the NTAK04 or NTDK78, while the system
is operating on battery backup.
Three types of reserve battery power can be used with the Option 11C system:
• The NTAK75 battery box (shown in Figure 4 on page 20) provides a
minimum of two hours of reserve DC power.
Equipment identification Page 19 of 408
CAUTION
Option 11C Planning and Installation Guide