3--3
Powerware BPIV Parallel Cabinet Installation and Operation
164201409 REV. B
101503
3.2.1
Normal Mode
In Normal mode, utility AC power is supplied to the UPMs. Power from the output
of the UPMs is then supplied to the Parallel Cabinet for parallel operation. The
Parallel Cabinet then supplies the critical load with clean, filtered AC power.
Figure 3---1 shows the path of electrical power through the Parallel System when
the Parallel system is operating in Normal mode.
PATH OF ELECTRICAL POWER
UPM1
UPM2
UPM3
UPM4
BYPASS
INPUT
OUTPUT TO
CRITICAL
LOAD
BATT
UPM
INPUT
BATT
BATT
BATT
PARALLEL CABINET
OPEN
CLOSED
CONTACTORS
UPM SWITCH 1
UPM SWITCH 2
UPM SWITCH 3
UPM SWITCH 4
CONTACTOR
BYPASS
K4
FROM
BYPASS
SOURCE
BYPASS
INPUT
SWITCHES
Figure 3---1. Path of Current Through the Parallel System in Normal Mode
If the utility AC power is interrupted or is out of specification, the UPMs
automatically switch to Battery mode to support the critical load with no
interruption. When utility power returns, the UPMs returns to Normal mode.
If the UPMs become overloaded or unavailable, the Parallel System switches to
Bypass mode. The Parallel System automatically returns to Normal mode when the
overload condition is cleared and system operation is restored within specified
limits.
