Filter
Top Products
70 Operation
Table 1 Alarm Mess ages - Meaning and Corrective Action
Alarm
Message
Cabinet
Location
Special
Functions
Meaning and
Corrective Action in Brackets [ ]
AC INPUT
Input Fail MMU — The rectifier input line voltage is outside of specified limits or the
input circuit breaker is opened while t he battery circuit breaker
remains closed. The battery supplies power to the c ritical load
through the UPS inverter.
DC BUS
DC Ground Fault MMU L, S Either the positive (+) or negative (-) DC bus is grounded. No transfer
or shutdown occurs.
[Contact Liebert Global Services at once. Do not attempt to locate or
repair the fault.]
DC Capacitor
Fuse Blown
MMU D, F, S At least one DC capacitor fuse has opened. The UPS module is
taken off-line and the input and battery circuit breakers trip open.
[Contact Liebert Global Services at once. Do not attempt to reset the
circuit breakers.]
Battery CB Open MMU R, S The module battery circuit breaker (MBD) is open. This circuit
breaker can be opened either manually or automatically in a UPS
shutdown procedure. If the UPS is operating with this breaker open,
the critical load is not protected from loss of the utility source
power.
[After AC power is restored and the DC bus is at 100% operating
voltage, manually close the battery circuit breaker so the rectifier can
charge the battery.]
Battery
Discharging
MMU R, S The battery is discharging. This occurs whenever the battery
supplies power to the load for more than 5 seconds because of input
power failure, a rectifier problem, or an overload condition. If the
input power or a source of auxiliary power is restored to the UPS
module, the UPS automatically returns to normal operation.
[Watch the battery voltage carefully. Reduce the load (begin
controlled shutdown) to extend the battery back-up time. Reset the
UPS alarms after the input power is restored. The message clears
after 30 seconds.]
Low Battery
Warning
MMU R, S The battery voltage is approaching the minimum discharge voltage
(approximately 5 minutes remaining).
[Complete the controlled shutdown of the critical load. Reset the
alarms if the input power is restored before shutdown.]
Low Battery
Shutdown
MMU D, F, L, S The battery voltage has decreased to the minimum discharge value.
The UPS module is taken off-line (no power to the critical load)
and the battery and input circuit breakers trip open.
[Perform a UPS system start-up procedure when AC power
becomes available.]
DC Over-Voltage
Shutdown
MMU D, F, L, S The maximum preset value of the DC Bus voltage has been
exceeded. The UPS module is taken off-line and the input and
battery circuit breakers trip open.
[Contact Liebert Global Services at once. A fault may have occurred
within the UPS. Do not attempt to reset the circuit breaker.]
BYPASS
Load On Bypass SCC D, E, F The critical load is being supplied power from the bypass line, and is
therefore exposed to utility power disturbances.
[Clear all of the alarms before attempting to retransfer the load from
the bypass line to the UPS.]
Table 1 Abbreviations
D = auto-dial; L = latches
E = reports only; R = remote
F = freezes; S = summary
D* = auto-dial initiated by Auto Transfer to Bypass if load is on UPS whenalarm occurs
D# = auto-dialinitiated through Module N (1-6) off-line
DISCONTINUED
PRODUCT