Hard Fault - ABB HiPerGuard MV UPS User Manual

81
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8.7 Hard fault

Hard faults are extremely rare situations where multiple failures occur at the same time, and the system is not ca-
pable of holding the voltage for any longer. In the case of hard-parallel configuration, the remaining units will sup-
port the load (N+1 configuration, for instance). If the load power exceeds the remaining units overload capability,
the system will be commuted to bypass mode.
8.7.1 During Power Conditioning mode
Step User Action
System encounters a hard fault, which prevents it from
1
normal operation.
2
3
4
—
Table 8.07: System
reaction to fault
while in PCM.
—
Note: Closing the
1
bypass applies for
single unit configu-
ration where no unit
redundancy is achieved.
8.7.2 During Independent mode
Step User Action
System encounters a hard fault, which prevents it from
1
normal operation.
2
3
—
Table 8.08: System reac-
tion to fault while in IM.
System Response
MV UPS output voltage synchronizes with util-
ity voltage magnitude, frequency and phase,
while simultaneously commands Sabp to
close
1.
When Sabp is closed, Sin and Sout are com-
manded to open.
After Sin and Sout are opened, MV UPS stops
the PEBBs and reverts to bypass mode.
System Response
Commands to close Sabp. If MV UPS is locked
with input voltage then simultaneously syn-
chronizes load voltage with mains voltage fre-
quency, phase and magnitude. Otherwise, MV
UPS waits in the previous state until Sabp
closes.
When Sabp is closed or Sabp close request
time-out period is elapsed then MV UPS opens
Sout and Sin. MV UPS stops the PEBBs and re-
verts to bypass mode.