Battery Backup Mode; External Maintenance Bypass (Customer Supplied) - Toshiba 4200FA XT Installation And Operation Manual

6.1.3

Battery Backup Mode

The following illustration shows power flow during the battery backup mode. In the event of
an AC power failure the batteries of the UPS instantly begin supplying DC power to the UPS
to the main inverter circuit. This circuit converts the DC power into AC power. The AC power
is available at the output of the unit. This back-up process will continue until the UPS battery
voltage drops below a specific minimum level. At which time the batteries cease supplying
power to the load.
This minimum level is the shutdown voltage minimum (V min). The rated battery voltage table
on page 36 shows (V min). The battery backup time and discharge process is explained in
Section 6.2.
Power Flow
Isolating
XFMR
Input
Power
Power flow in battery backup mode for the 4200FA 80 kVA UPS
6.1.4

External Maintenance Bypass (Customer Supplied)

An external maintenance bypass may be installed in parallel with the UPS to allow servicing
of the UPS while maintaining power to the load. Contact an authorized service
representative for further information.
CAUTION
4200FA XT 80kVA Installation and Operation Manual
MCCB
Converter
Ensure the UPS is set to BYPASS mode before switching the
external bypass from UPS to MAINTENANCE BYPASS.
High transient currents may result if the external bypass is engaged
while the UPS is in normal mode.
Static
Bypass
Inverter
Charger/
Chopper
External
Batteries
Output
Power
31