Powerware UPS Sidecar Powerware 9390 - Manual (Page 32)

UNDERSTANDING OPERATION
EATON Powerware ® 9390 UPS Sidecar Installation and Operation Manual S 164201586 Rev E www.powerware.com 3-2
3.1.2 Maintenance Bypass Mode with UPS Sidecar
An MBP is used to safely supply utility power to the critical load during periods of
UPS maintenance or repairs. The bypass source supplies the commercial AC power
to the load directly.
When the MBP is closed, the load is wrapped around the UPS while power is still
supplied to the load by the UPS through the MIS. The MIS is then opened, isolating
the UPS from the Bypass power source. The UPS can be safely shut down and power
removed from the UPS without interrupting power to the critical load. If the optional
BIB and RIB are installed, the BIB and RIB are opened to remove power from the
UPS. Otherwise, external upstream breakers are used to remove power. The UPS
now can be serviced or replaced safely.
The critical load is not protected while the UPS is in Maintenance Bypass mode.
Figure 3-2 shows the path of electrical power through the UPS Sidecar when
operating in Maintenance Bypass mode.
AC INPUT
TO UPS
OUTPUT TO
CRITICAL LOAD
UPS SIDECAR
RIB
(OPTIONAL)
BIB
(OPTIONAL)
MIS MBP
AC INPUT
TO BYPASS
TO UPS RECTIFIER
INPUT
FROM UPS OUTPUT
TO UPS BYPASS
INPUT
MAIN POWER FLOW IN UPS MODE
MAIN POWER FLOW IN MAINTENANCE BYPASS MODE
Figure 3-2. Path of Current Through the UPS Sidecar in Maintenance Bypass Mode
3.2 Parallel Redundant Configuration
Refer to the applicable Powerware 9390 installation and operation manual, listed in
paragraph 1.5, for parallel theory of operation.