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Troubleshooting
28
Fault and Bypass
indicator LEDs
and diagnostic
LED C and E are
illuminated.
UPS shutdown due to a
command from the
communications port(s).
Your UPS has received a
signal or command from
the attached computer. If
this was inadvertent,
ensure the communication
cable used is correct for
your system. For
assistance, contact your
local dealer, Liebert
representative or the
Liebert Worldwide Support
Group.
AC LED is
flashing.
UPS detected a line-to-
neutral reversal or a loss of
proper grounding;
continuous horn and UPS
will not start. This is active
only when power is first
applied to the input. Once
the UPS is running, the AC
LED will not start flashing,
even if the input wiring is
changed.
Contact a qualified
electrician to verify site
wiring.
Battery LED is
flashing.
Battery source is not
available; continuous horn.
Check battery connections,
completely power down
and restart UPS.
NOTE: If the battery circuit
opens while the UPS is
running, it will be detected
when the next battery test
is performed.
Bypass LED is
flashing.
Bypass voltage is present,
but is disabled for use
because the voltage or
frequency is outside
acceptable limits.
The AC input powers the
PFC input and serves as
the bypass source. If the
AC is present but the
voltage or frequency
exceeds the acceptable
range for safe operation
with a load, the bypass will
be disabled and this LED
will flash, indicating that the
bypass is unavailable.
Table 1 Troubleshooting guide (continued)
Problem Cause Solution