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User Guide APC BC300 Series 40kW 208/450/480V UPS 17
Low DC
shutdown (This
alarm is normal
when the UPS
has run on
battery for a
long time)
The UPS has been running on
battery power because of a power
outage or problems in the AC input.
Battery voltage has dropped below
the shutdown setting, and the UPS
has shut down. If bypass is within
tolerance, the unit will transfer to
static bypass operation. If not, the
unit will transfer to stand-by and
will not supply output voltage.
If the UPS is programmed for
auto-start, it will automatically
restart when the power outage
ends and AC input is again
available. If the UPS is not
programmed for auto-start, you
can restart the UPS when the
power outage ends by pressing
the green button inside the door.
Low DC
warning (This
alarm is normal
when the UPS
has run on
battery for a
while)
The UPS has been running on
battery power for a while because of
a power outage or problems in the
AC input. Battery voltage has
fallen to the warning alarm setting.
If the APC BC300 Series is
operating on battery, the unit’s
status will not change, but battery
voltage will eventually drop to the
shutdown setting. At this point, the
unit will shut down and sound a
“Low DC shutdown” alarm. If the
“Low DC warning” alarm occurs
during a battery capacity test, the
unit transfers back to normal
operation.
If the unit has not been running on
battery power, call APC Technical
Support.
If possible, restore AC input
power to the UPS. If you cannot
do this, prepare for a possible Low
DC shutdown by shutting down
the loads (protected equipment)
connected to the UPS.
Mains freq. is
out of tolerance
The utility (AC input) frequency is
out of tolerance. The unit transfers
to battery operation. If utility
returns to a frequency within
tolerance, the unit transfers back to
normal operation. If not, the unit
continues to run on battery until
the “Low DC shutdown” alarm
occurs. Then, if bypass is within
tolerance, the unit transfers to
bypass. If not, the unit transfers to
stand-by and does
not supply
output voltage.
Ask an electrician to make sure
that the correct input frequency is
available to the UPS. The
electrician must correct any
problems in input frequency. If
input frequency is correct, call
APC Global Service.
Mains is
moment. out of
tolerance (This
alarm occurs
during a power
outage)
The utility (AC line voltage) was
momentarily too high or too low.
The unit transfers to battery; if
utility returns to a frequency
within tolerance, the unit transfers
back to normal operation.
If possible, restore AC input
power to the UPS. If AC input is
available to the UPS, ask an
electrician to make sure that 1)
the correct input voltage is
available to the UPS. 2) this
voltage is within an acceptable
UPS range
Table 5: Possible Alarms