UT340, UT360, UT380, and UT3100
Planning and Installation Manual
24
CAUTION
Before you switch the UPS bypass switch from “UPS” to “LINE”, 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. At the maintenance bypass cabinet (MBC), make sure 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 208 V nominal or 25 volts apart for
480 V nominal, check the connections and correct any wiring problems before
continuing.
14. At the maintenance bypass cabinet (MBC), make sure the UPS output voltage and the AC
line input voltage are in phase. To do this, measure the AC voltages 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 input
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.
