5
Fig 2-2 Normal mode operation diagram
2.3.2 Battery Mode
Upon failure of the AC mains input power, the inverter of power modules, which
obtain power from the battery, supply the critical AC load. There is no interruption in
power to the critical load upon failure. After restoration of the AC mains input power,
the “Normal mode” operation will continue automatically without the necessity of
user intervention.
Fig 2-3 Battery mode operation diagram
Note
With the function of Battery cold start, the UPS may start without utility. See more detail in
section 5.1.2.
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.
Summary of Contents for EA990 G5 10
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