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Modes of Operation
The Power Array functions in one of four modes of operation,
depending on user commands, the status of the AC utility
voltage, and the condition of the Symmetra
TM
itself. The four
modes are Load-Disconnect, On-Line, On-Battery, and By-
pass. The PowerView interface reports the operating mode.
Load-Disconnect Mode
In the load-disconnect mode, incoming AC utility power is
present and the system is internally powered, but no output
power is delivered to the load equipment. The Symmetra
TM
enters the load-disconnect mode at the initial power up, when
the system enable switch is switched to the “on” position. When
the system is operating on-line, and the “load off” command
is entered in the PowerView interface, it returns to the load-
disconnect mode. Figure I-3 illustrates the power flow when
the system is operating in the load-disconnect mode.
Fig I-3 Load-Disconnect Operating Mode
On-Line Operating Mode
The on-line operating mode is the “normal” operating mode.
When the system is in the on-line operating mode, the Power
Array receives power from the AC utility, and delivers condi-
tioned power to the load equipment. The Power Array main-
tains proper battery charge, regulates the output voltage and
frequency, and protects the load from surges and electrical
noise. Symmetra
TM
will operate in this mode if it has been
commanded to turn the load on, the incoming utility voltage
is present and functioning properly, and there are no prevent-
ing abnormal conditions, such as an overload. See figure I-4
for a diagram of the power flow when the system is in the on-
line operating mode.
Fig I-4 On-Line Operating Mode