NS3000 UPS 60KVA~120KVA User Manual
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2.3.3 Bypass Mode
If the inverter overload capacity is exceeded under Normal mode, or if the
inverter becomes unavailable for any reason, the static transfer switch will
perform a transfer of the load from the inverter to the bypass source, with no
interruption in power to the critical AC load. Should the inverter be
asynchronous with the bypass, the static switch will perform a transfer of the
load from the inverter to the bypass with power interruption to the load. This is
to avoid large cross currents due to the paralleling of unsynchronized AC
sources. This interruption is programmable but typically set to be less than 3/4
of an electrical cycle, e.g., less than 15ms (50Hz) or less than 12.5ms (60Hz).
The action of transfer/re-transfer can also be done by the command through
monitor.
Rectifier
AC/DC
Main
Static Bypass
Manual Bypass
Inverter
DC/AC
Charge/
Discharge
Output
Battery
Bypass
Fig. 2-5 Bypass mode operation diagram
2.3.4 Maintenance Mode (Manual Bypass)
A manual bypass switch is available to ensure continuity of supply to the critical
load when the UPS becomes unavailable e.g. during a maintenance procedure.
(See Fig.2-6).
Rectifier
AC/DC
Main
Static Bypass
Manual Bypass
Inverter
DC/AC
Charge/
Discharge
Output
Battery
Bypass
Fig .2-6 Maintenance mode operation diagram
Danger
During Maintenance mode, dangerous voltages are present on the terminal of input, output
and neutral, even with all the modules and the LCD turned off.
Summary of Contents for NS3000 Series
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