6
connected to the W terminal. If the phase relationship is incorrect (see BAD ROTATION below), the
problem is easily corrected by swapping any two of the X, Y, and Z wires. Refer to Figure 3, UPS
External Wiring, and Figure 4, AC Wiring Terminal Block.
2.
A copper lug marked “GND” is supplied on the upper right side of the UPS for the purpose
of grounding the cabinet to earth ground. This lug will accommodate wiring between 8 and
2 AWG for units up to and including 30 KVA, and wiring between 8 and 1/0 AWG for
systems above 30 KVA. A wire size that meets local electrical codes must be selected and
may be routed with the AC supply wiring to the service distribution panel earth ground.
Alternatively, a hole can be drilled and tapped on the backside of the cabinet frame (not
the panel), near the bottom to provide an external chassis ground. Care should be taken
so that metal particles produced by such operation are not allowed to come in contact with
any internal electrical components.
3.
If the proper rotation has not been selected, the UPS, when turned "ON", will indicate that
the incorrect rotation has been chosen. The LCD Display #1 or #2 screens will indicate
"AC LINE PROBLEM" on the bottom line, and the status line will read "BAD ROTATION."
In this case the electrician will be required to swap two of the X, Y, and Z wires in the UPS
input to obtain the correct rotation.
Note:
In addition to checking for proper phase rotation,
the UPS will also examine the phase of each leg and the angle between phases. The LCD
screen will indicate any problems detected.
Figure 4
AC Wiring Terminal Block
X
Y
Z
W
X
Z
W
Y
INPUT VOLTAGE
208V/3 Y/60HZ
OUTPUT VOLTAGE
208V/3 Y/60HZ
Φ
Φ
Connecting the Load:
Wire the UPS “OUTPUT VOLTAGE” terminals to the load distribution panel,
making sure that all loads are off (Refer to Figure 3, UPS External Wiring and Figure 4, AC Wiring
Terminal Block). Terminals marked X, Y, and Z refer to the three phases where the X-phase leads the
Y-phase which in-turn leads the Z-phase, all by 120 degrees. The W terminal is again the neutral of the
3-phase Wye output. Internal wiring to this terminal block is marked with red (Y-phase), blue (Z-phase),
and white (neutral) tape. Refer to Table 1 for current carrying capabilities that this wiring must have and
Table 2 for allowable wire size. An Allen wrench should be used to torque the lugs to the specifications
given in Table 2.
External Battery Cabinet:
If an external battery cabinet is supplied with the UPS system, then an
additional DC breaker marked “EXTERNAL BATTERY BREAKER” or “BATTERY BREAKER” will also
be supplied on the left side of the UPS cabinet. A qualified electrician can find the pilot hole for the
External Battery Cabinet wiring just above this breaker in the UPS cabinet. In the same manner as
described for the AC wiring, the electrician would establish the proper punch, install the proper conduit
and wiring, and bring the two external battery wires to the External Battery Breaker. See ADDING
AUXILIARY BATTERY CABINETS.
