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CENTRIC 3x480, User Guide, rel. 1.7
10.2
Troubleshooting “Dc low”
This procedure is to be performed only as directed by Table 13 above.
1.
The usual cause of a low dc voltage is that the battery is charging after a deep discharge or a battery
test, and its charging current is limited by the current limiting mechanism.
2.
Use a calibrated voltmeter to measure the dc voltage between both battery connection terminals and
midpoint (i.e., between “+” and midpoint, and between “–“ and midpoint. If the voltage as measured by
the voltmeter differs from the value measured by the UPS itself, the modules’ dc meters need to be
recalibrated.
3.
If the dc voltage displayed by the UPS is accurate (i.e., matches your voltmeter reading), wait 20 or
30 minutes and check the dc voltage again. If the voltage has risen, this is an indication that the
battery is being charged. To accelerate the process, verify that the battery setup values are correct,
as follows.
3.1
Go to “Setup > Battery > Battery capacity”. Verify that the defined battery capacity in ampere/hours
matches the rating of the battery.
3.2
Go to “Setup > Battery > Battery current”. If the current limit is defined as 10 %, increase it to 20 %.
If dc voltage begins to rise you can return the current limit value to 10 % and wait for the battery to
charge fully. This could take up to 10 hours, depending on the state of the battery.
4.
If you have carried out the above instructions and the dc voltage remains low, do the following:
4.1
Disconnect batteries from the UPS either by switching of the battery circuit breaker or by removing
the battery fuses.
4.2
Transfer the load to bypass.
4.3
Cancel any battery test that may have started automatically.
4.4
Shut down the bottom UPS module (“Operation > Turn on/off > Modules off”, select the module in
question on the screen and choose “Complete shutdown”).
See if the dc voltage returns to a normal value. If so, you have found the problematic module.
Replace the module.
4.5
If the dc voltage did not return to normal, switch the module back on
(“Operation > Turn on/off > Modules on”),
then shut down next module and see if the dc voltage returns to a normal value.
Continue likewise until you have checked all of the modules, using the “complete shutdown”
command.
