GE Industrial Solutions SG Series 400 & 500 Operating Manual - Manual (Page 14)

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OPM_SGS_USM_M40_M50_2US_V010.doc User Manual SG Series 400 & 500 UL S2
4.2.3 Utility failure operation
When the Utility is no longer within acceptable
tolerances, the Battery will provide the DC power to the
Inverter.
The Inverter will maintain continuous AC power to the
Load until the Battery Voltage reaches the lower limit of
the Inverter operation capability.
During the discharge, the LCD screen displays the
estimated time the Battery can support the critical Load.
Prior to the Battery completely discharging, the "stop
operation" alarm (shutdown imminent) warns the
operator that the Battery is almost discharged and the
UPS is about to shut down.
Fig. 4.2.3-1 Block diagram Utility Failure operation
In case of parallel operation
With a parallel system for power capacity (see Section 4.3)
• With the Bypass Utility power available, a low Battery warning on any unit will cause the Load to
be transferred to Utility (after a selectable time delay).
• With Bypass Utility power not available, a low Battery warning on any unit will start the “stop
operation” timer (adjustable). The Load will shut down at the end of the “stop operation” time period.
With a parallel system for redundancy (see Section 4.3)
• When a Battery low warning occurs on a unit not necessary to support the present load, this unit
will shut down after a timeout period (selectable). The Load is shared between the other units.
As the warning occurs on one unit necessary to support the present load, the system starts the
"stop operation" timeout (selectable).
The Load will shut down at the end of the “stop operation” time period.
4.2.4 Utility recovery operation
As soon as the AC input power recovers, the Rectifier will
start automatically, supplying DC power to the Inverter
and recharging the Battery.
If the Inverter was previously shut down due to low
Battery, the Load will be initially powered by Utility
through the Automatic Bypass.
When the Battery is recharged enough to ensure a
minimum time of operation with the present load, the
Inverter will start automatically and the Load will be
transferred back to the Inverter.
Fig. 4.2.4-1 Block diagram Utility recovery operation
In case of parallel operation
When the AC input power recovers, the Rectifiers will start up sequentially, according to their
number in the parallel system. This minimizes the initial inrush current.
The Inverters will start up automatically, but only when the Battery has recharged enough for a
minimum runtime with the present load.
When enough Inverters to supply the Load have been restarted, the Load will be transferred from
the Automatic Bypass back to the Inverter output.