34 Chapter 4 Operator Control And Display Panel
APM 300 Integrated UPS Single Module And Parallel System User Manual
Inverter Asynchronous
This alarm is triggered by an inverter software routine when the inverter and bypass
waveforms are misaligned by more than six degrees in phase. The amplitude threshold is
fixed for ±10% rating. This alarm resets automatically once the condition is no longer
true.
1. First check if the alarm Bypass unable to trace or Bypass abnormal occurs. If so, solve it
first.
2. Verify the waveform of the bypass voltage
Inverter fault
Inverter output voltage outside specifications. Load transfers to bypass. The faulty power
module will shut down and open output relay, and the remaining power modules will
remain online
At least one of the cooling fans failed
Bypass STS Fail
At least one of the STSs at the bypass side is open or shorted. This fault is locked until
power-off
Output Fuse Fail
At least one of the inverter output fuses is blown. The inverter shuts down, and the load
transfers to bypass if the remaining power modules are insufficient to support the load
The UPS is operating but the redundant control power is abnormal or not available
Unit Over load
This alarm appears when the load arises above 105% of the nominal rating. The alarm
automatically resets once the overload condition is removed.
1. Find out if this alarm is true by checking which phase has overload through the load (%)
displayed on the LCD.
2. If this alarm is true, measure the actual output curr
ent to confirm if the displayed value is
correct.
3. If yes, disconnect the non-critical load.
In a parallel system, this alarm will be triggered if the load is severely unbalanced
System Over load
This alarm appears when the total load rises above 105% of the nominal rating of the
parallel system. The alarm automatically resets once the overload condition is removed.
1. Find out if this alarm is true by checking which phase of which unit has overload through
the load (%) displayed on the LCD.
2. If thi
s alarm is true, measure the actual output current to confirm if the displayed value is
correct.
3. If yes, disconnect the non-critical load.
This alarm will be triggered if the load is severely unbalanced
Unit Over load Timeout
The UPS overload status continues and the overload times out.
Note that:
1. The highest loaded phase will indicate overload time-out first.
2. When the timer is active, then the alarm Unit Over load should also be active as the load
is above the nominal rating.
3. When the time has expired, the load transfers to static bypass. The inverter shuts down
and will restart after 10 seconds.
4. If the load decreases to lower than 95%, after five minutes, the system will transfer back
to the inverter. Check the load (%) displayed on the LCD to confirm if this alarm is true. If
the LCD tells that overload happens, then check the actual load and confirm if the UPS has
overload before the alarm happens
Shutdown
Both the bypass and inverter voltages are abnormal, and the output is off
The inverter has overcurrent fault
Bypass Phase Reversed
The phase rotation of the bypass voltage is reversed. Normally, phase B lags 120 degrees
behind phase A, and phase C lags 120 degrees behind phase B.
Check that the phase rotation of the UPS bypass supply is correct
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