23
MANUAL BYPASS
AC OUTPUT
BYPASS
STATIC
SWITCH
INVERTER
DC-LINK
BATTERY
CHARGER
BATTERY PACK
AC INPUT
BYPASS
LNE
RECTIFIER-BOOSTER
Fig. 15.
UPS power flow in normal mode.
4.5.2. Battery mode
In the event of an AC power supply fault, the rectifier-booster
switches its input power source from the AC network to the
battery without interruption. The battery voltage decreases ac-
cording to the discharge current value, but the rectifier-booster
is responsible for keeping the direct voltage to the inverter input
within the nominal working values.
If the supply is restored before the batteries are completely dis-
charged, the system will return to normal operation automatically:
rectifier operating in AC/DC conversion, charger charging batteries,
inverter continues operating.
Otherwise, as soon as the batteries reach the discharge limit
(end of autonomy), the inverter switches off, and if the unit
has a common input for the rectifier and the bypass, the power
supply of the load is interrupted ("black-out"). For units that
have a bypass line that is independent of the rectifier AC input,
if, upon reaching the battery discharge limit, the voltage in the
bypass line is within the tolerance limits, the power supply of
the load is transferred to this emergency line.
After a stop due to the end of autonomy, when the power
supply is restored, the rectifier restarts the charging of
the batteries. Likewise, if the power supply of the loads was in-
terrupted (common bypass to rectifier input),
they are initially
supplied via the static bypass switch. The inverter will
then restart and will reconnect to the output.
MANUAL BYPASS
AC OUTPUT
BYPASS
STATIC
SWITCH
INVERTER
BATTERY
CHARGER
BATTERY PACK
DC-LINK
RECTIFIER-BOOSTER
BYPASS
LINE
AC INPUT
Fig. 16.
UPS power flow in battery mode.
4.5.3. Bypass mode
In this operating mode, the voltage supplied to the loads cor-
responds directly to the emergency (or bypass) line, connected
to the output by controlled thyristors. The inverter is discon-
nected from the output (open relays), and this converter can
be completely stopped. The rectifier-booster and the charger
continue to operate, so the batteries will continue to maintain
their optimum level of charge.
This is an operating mode where the loads are not "protected"
against disturbances in the AC network or even power outages.
From normal operating mode, the output load can be trans-
ferred to the bypass line, both via manual command by the
operator or via communications, as well as automatically via
the UPS (its management logic), given specific circumstances
(alarms), such as:
SLC CUBE4
- UNINTERRUPTIBLE POWER SUPPLY SYSTEM
-
USER MANUAL
