67
UPS for 480 Vac Grid, User Guide, doc. rel.4.0
Figure 45: dc bus terminals
To detect and correct any inaccuracy in the UPS’s display of the dc voltage:
1.
Verify that all dc relays are ON.
2.
Remove the back panel for the fuses exposing the positive, negative, and mid-point bus
terminals.
3.
Measure the actual battery voltage with a calibrated voltmeter.
The dc terminals are accessible from the rear of the UPS. (Refer to positive, negative, and mid-
point in Figure 45).
4.
While observing all required safety precautions, measure the voltage between the negative
(“–“) dc terminal and the midpoint terminal.
5.
Compare your measured value to the number to the right of the screen (Figure 41), which is
the UPS’s measurement. If your measured value differs from the UPS’s measured value, enter
your measured value into the field labeled “battery negative dc voltage”.
6.
Next, measure the voltage between the positive (“+“) battery terminal and the midpoint bus. If
your measured value differs from the UPS’s measured value, enter your measured value into
the field labeled “battery positive dc voltage” (Figure 41).
7.
Select the Confirm button to apply the corrected positive voltage measurements.
