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CENTRIC 3x480, User Guide, rel. 1.7
103
10.3
Troubleshooting “Bypass mode”
This procedure is to be performed only as directed by Table 13 above.
1.
The load can be transferred to bypass for any of the following reasons:
a) command from the controller: either a manual command, or due to overload of the inverter.
b) command from the static switch panel.
c) command from a parallel connected UPS, if any.
d) inverter RMS voltage detection: voltage is out of specified range (±10 % from nominal value).
e) inverter voltage fast detection: sag to zero volts (blackout) or out of range of ±15 % (brownout)
for 3 mS.
f) inverter contactor fault.
g) SCR fault.
In cases “f” and “g” above, the load is locked on bypass to prevent recurring back-and-forth transfer of
the load. Such repeated rapid transfer can be dangerous for the load. The load will also be locked on
bypass automatically if the static switch performs 7 load transfers in 10 minutes. To return the load to
the inverter in such cases, issue the following instruction from the controller:
(“Operation > Load > Transfer load to inverter”).
2.
To transfer the load manually, go to “Operation > Transfer load” and select “Transfer load to inverter”..
3.
If the static switch could not transfer the load to the inverter, and the load is locked on bypass after
each attempt to transfer the load to the inverter, the static switch must be repaired. Either the static
switch’s inverter cantactor or SCR is faulty.
