Installation manual

UT340, UT360, UT380, and UT3100
Planning and Installation Manual
27
CAUTION
Before
you switch the maintenance bypass breaker (MBB) “ON,” use the steps below to
check for correct voltage, phasing, and system operating mode.
12. Program the unit into static bypass operation:
a. Press to access the user parameters.
b. Press the or key until the display shows
Bypass operation: OFF
.
c. Press to turn static bypass operation on. The display should show
Bypass
operation
.
13. Switch the UPS output breaker (UOB) “ON”.
14. At the maintenance bypass cabinet (MBC), make sure that the UPS output voltage is
approximately the same as the AC line input voltage (there may be slight differences). Use a
true RMS voltmeter to measure the phase-to-neutral voltage at the MBC AC line input and
the MBC output.
MBC AC Line Input MBC Output
a.
L1
to
neutral
_______VAC
L1
to
neutral
_______VAC
b.
L2
to
neutral
_______VAC
L2
to
neutral
_______VAC
c.
L3
to
neutral
_______VAC
L3
to
neutral
_______VAC
The voltages in the first column should be similar to the voltages in the second column.
If the voltages are more than 10 volts apart for 208V nominal or 25 volts apart for
480 V nominal, check the connections and correct any wiring problems before
continuing.
15. At the maintenance bypass cabinet (MBC), make sure the UPS output voltage and AC line
input voltage are in phase. To do this, measure the AC voltage between the following points
at the MBC AC line input and the MBC output:
MBC AC Line Input MBC Output
a.
L1 input
to
L1 output
_______VAC
b.
L2 input
to
L2 output
_______VAC
c.
L3 in
p
ut
to
L3 output
_______VAC
These readings must not be more than 10 VAC!
If they are, call BEST’s Technical
Support Center or your local BEST office.