Operation 79
3.2.2 OK To Transfer
TheOK to Transfer status message will be displayed when thebypass line and UPS system output power are
bothavailable, their voltage, frequency,and phase synchronization are matched within specifications,and the
StaticSwitch Disconnects are closed (ON). An alarm message may be displayed to indicateLoad On Bypass. If
noalarm is displayed, the operating status is Load On UPS.
Whenthe OK t oTransfer message is displayed, you can perform a manual transfer of the load from the UPS sys-
temto bypass, or a manual retransfer of the load from bypass to the UPS system.
Usethe Load Transfer Proceduresscreen at the SCC when performinga manual transfer. Referto 3.3.2 - Load
Transfer Procedures.
TheUPS system control logic at the SCC will initiatea nautomatic transfer to bypass if an overload condition
exceedsthe system current versus time window,or if a UPS module is taken off line while the system is operat-
ingin the non-redundant mode. An automatic retransfer to the UPS system may be initiated when recovering
fromsystem overloads lasting less than five minutes. Refer to 3.4 - Automatic Operations.
Figure 48 Load on Bypass (UPS Available)
NOTE
Whenthe critical load is being supplied power from the bypassline, it is exposed to
utilitypower disturbances.
BIB
SKRU
MIB
MBB
I
R
#2UPS
CB1
CB2
I
R
#1UPS
CB1
System
Controls
I
R
#3UPS
CB1
CB2
RIB RIB
CB2
RIB BFB
Output
SBB
SBS
SCCT
SCCT
(canaccommodate up t o 6UP S modules)
ToCriticalLoad
Battery
MBD
Battery
MBD
Battery
MBD
DISCONTINUED
PROD U C T