OPERATION
Step User Action System Response
1 Press “Stop”
2 If the MV UPS system is in Independent mode
or the utility voltage is not within acceptable
limits, the system will ask the operator to
confirm to abort the discharge and initiate
system stop
3 Commands to Close S
abp
while simultaneously
MV UPS (s) load voltage synchronize(s) with
utility voltage magnitude, frequency and
phase
4
When S
abp
is closed MV UPS(s) block(s) will
command to open S
out
and then S
in
5
After S
out
and S
in
are opened, system will stop
PEBBs
Table 8.3: MV UPS system stopping steps
8.4. Independent mode
The MV UPS transfers from the power conditioning mode to Independent mode during deep sag events
and outages according to the input breaker management curve.
Step User Action System Response
1
No user action required; the system will
operate fully autonomously during this event
2
System detects an event when utility voltage
drops below specified threshold level for a
limited time which is based on S
in
operation
characteristics curve
3 The MV UPS opens S
in
of each MV UPS
4 The MV UPS regulates the load voltage with
internal frequency and voltage as its
references
Table 8.4: MV UPS transferring automatically into Independent Mode
The MV UPS(s) is (are) fully supplying the load active and reactive power requirements while being
disconnected from the input. The system monitors for the return of a reliable power supply to enable
resynchronization.
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