Lucent Technologies Lineage
®
2000 ECS Battery Plant H569-403
3 - 10 Engineering, Planning, and Ordering
Issue 4 February 1997
RECHARGE FACTOR is a term that is sometimes used to
describe available recharge capacity. The recharge factor is the
total charge current divided by the List 1 drain. Typical recharge
factors range from 1.20 to 1.50.
r.
Minimum recharge factor: ____
The minimum initial rectifier requirement for float operation is
derived from the Plant List 1 Drains calculated in Table 3-A.
Customer practices MAY dictate any combination of the
following rectifier engineering conventions.
•
At least one on-line spare rectifier must be included in the
plant for increased reliability.
•
Any on-line spares must be the same size as the largest
rectifier in the plant.
•
At least 20 percent additional capacity must be included in
the plant to provide recharge capacity and spares.
Refer to paragraph “Rectifier Sizing” for specifics on sizes and
quantities of rectifiers for the ECS Battery Plant.
Battery String
Voltage Drop
and Balancing
The rectifiers, while recharging or floating the batteries,
maintain a constant voltage at the battery plant bus bars. When
batteries are accepting recharge current after a discharge, there
is a finite voltage drop from the charge bus bars inside the ECS
bay to the battery string terminals. This voltage drop is, of
course, proportional to the magnitude of the recharge current.
Any voltage drop from the battery plant bus bars to the terminals
of each battery string will tend to slow the rate of battery
recharge and delay their readiness for future discharges. The
same cable resistance responsible for voltage drop during
recharge creates a voltage drop during discharge as well.
Voltage drop during discharge can limit the effectiveness of the
batteries in supplying the necessary reserve.
For these reasons, the engineer should minimize the voltage drop
between bus bars and batteries by interconnecting them with the
largest practical wire size.
In battery plants with multiple, parallel strings of batteries, the
cable lengths from the dc distribution subsystem to each string
will be different. It is as important to balance the strings as it is
to minimize voltage drop. Multiple strings are balanced by
