This demand shall increase gradually to 100 percent of the rated full load
current plus the battery charging current over the specified time interval.
2.4.2.4
Sizing
Rectifier/charger unit shall be sized for the following two simultaneous
operating conditions:
a.
Supplying the full rated load current to the inverter.
b.
Recharging a fully-discharged battery to 95 percent of rated
ampere-hour capacity within ten times the discharge time after
normal ac power is restored, with the input protective device
closed.
2.4.2.5
Battery Charging Current
**************************************************************************
NOTE: Delete second step current limiting if the
UPS system will not be supplied with ac power from
an auxiliary generator system or if the generator
has been sized to accommodate the recharge current
of the battery.
**************************************************************************
a.
Primary current limiting: Battery-charging current shall be
voltage regulated and current limited. The battery-charging
current limit shall be separately adjustable from 2 percent to 25
percent of the maximum discharge current. After the battery is
recharged, the rectifier/charger unit shall maintain the battery
at full float charge until the next operation under input power
failure. Battery charger shall be capable of providing equalizing
charge to the battery.
b.
Second step current limiting: The rectifier/charger unit shall
also have a second-step battery current limit. This second-step
current limit shall sense actual battery current and reduce the
input power demand for battery recharging to 50 percent
(adjustable from 30 percent to 70 percent) of the normal rate
without affecting the system's ability to supply full-rated power
to the connected load. The second-step current-limit circuit
shall be activated by a dry contact signal from the generator set
controls and shall prevent normal rate battery recharging until
utility power is restored.
2.4.2.6
Output Filter
Rectifier/charger unit shall have an output filter to minimize ripple
current supplied to the battery; the ripple current into the battery shall
not exceed 3 percent RMS.
2.4.2.7
dc Voltage Adjustment
Rectifier/charger unit shall have manual means for adjusting dc voltage for
battery equalization, to provide voltage within plus 10 percent of nominal
float voltage.
SECTION 16265A
Page 21
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