VTI UDS MB and FD Series - Manual (Page 5)

Verify that the total load connected to the UDS does not exceed the rating of the
transformer supplied, i.e., 30 KVA, 45 KVA or 75 KVA.
If the optional primary disconnect switch is installed, terminate the feeder wiring at the
primary disconnect switch. Connect the three phase conductors in the cable (black, red
and blue) to the disconnect terminals identified as “L1”, “L2”, and “L3”, respectively.
Connect the ground conductor (green) to the ground lug provided in the primary
disconnect compartment of the cabinet. Make sure that these terminations are secure.
If the optional primary disconnect switch is not installed, terminate the feeder wiring at the
transformer located in the compartment at the bottom of the UDS cabinet. Connect the
three phase conductors in the cable (brown, orange and yellow) to the transformer primary
terminals identified as “H1”, “H2”, and “H3”, respectively. Connect the ground
conductor (green) to the ground lug provided in the transformer compartment of the
cabinet. Make sure that these terminations are secure.
Measure the phase to phase voltage of the power source that will feed the UDS cabinet.
Referring to the tap chart on the transformer, connect the numbered taps on each coil
which correspond most closely with the measured source voltage as shown in the table
below.
C a b l e S i z e
600V transformer rating Minimum wire size AWG
30 KVA 10 AWG
45 KVA 6 AWG
75 KVA 2 AWG
400/415 volt transformer tap chart
Line voltage Tap number
435 1
425 2
415 3
404 4
394 5