Dc Voltage Calibration - Gamatronic Centric 3x480 Vac User Manual

7.2.3.2

DC VOLTAGE CALIBRATION

This function is for correcting any inaccuracy in the Centric's display of the dc voltage. (This is the output
voltage of the dc-dc blocks, not the battery voltage. The rectifier's output voltage is fed to the inverter and is
also used to charge the battery.)
The Centric's readings are calibrated before the UPS leaves the factory, but over time or due to
environmental factors the Centric's dc measurements may drift slightly.
In this screen the Centric displays the dc voltage in two parts: a negative half and a positive half. For
example, if the UPS load was perfectly stable and the Centric's measurement was perfectly calibrated, the
dc voltage reading would be displayed as 435 Vdc negative and 435 Vdc positive.
Calibration of the dc-dc voltage must be done one dc block at a time. The Centric must be under low or no
load during the dc output voltage calibration
(Note: a password may be required to perform this function.)
To calibrate the Centric's display of the dc voltage:
1. Turn off all dc-dc blocks except for one ("Main > Operation > Turn on/off > Dc-dc on/off").
We suggest you calibrate the dc-dc blocks starting with the bottom-most block (see Figure 26).
2. The dc bus is located on the rear of the UPS (Figure 22). Using a calibrated voltmeter, measure the
actual dc voltage between the negative ("–") dc bus and the midpoint bus (Figure 22).
3. Compare your measured value to the number to the right of the screen, which is the Centric's
measurement. If your measured value differs from the Centric's measured value, enter your
measured value into the field labeled "negative dc voltage" (see Figure 25).
4. Next, measure the voltage between the positive ("+") dc bus and the midpoint bus bar. If your
measured value differs from the Centric's measured value, enter your measured value into the field
labeled "battery positive dc voltage".
5. Press the Confirm button to apply the corrected measurements.
6. Repeat the process for each dc-dc block, one block at a time, turning off all of the dc blocks except
the one being calibrated.
Figure 26: Dc-dc blocks
numbering sequence
CENTRIC 3x480, User Guide, rel. 1.7
G E
AMATRONIC LECTRONIC
Figure 27: Dc voltage calibration screen
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