Service Manual
Test Procedures
7 - 14
3x3 UPS
Issue 2 - November 2001
Primary and Secondary DC Bus Voltage Check (refer to Figure 7Ć7)
1.
Remove the UPS top cover.
2.
With a DVM check the secondary DC bus across F3 and F2 has fallen less than 20V dc.
3.
With a DVM check the primary DC bus across F1 and F4 has fallen less than 20V dc.
The UPS is now safe to carry out further investigation.
Note: The half DC bus level can also be monitored if required by connecting the
DVM across the +ve or Ćve fuse and the DC common (neutral) bus bar as
shown in Figure 7Ć7.
Figure 7-7
DC Bus Voltage check
F2
F3
Check Secondary DC
bus between Fuse F3
& F2
765V DC
To Check Half Secondary DC bus Voltage check for 382V DC between Fuse
F3 and Neutral Bus. (a similar check can be carried out from F2)