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Separate Power Source
Chiller control power usually comes from a control transformer located in the starter and
factory or field wired to the chiller control panel. In the event a separate transformer supplies
control voltage, it must be rated at 3 KVA, with an inrush rating of 12 KVA minimum at 80%
power factor and 95% secondary voltage. For control wire sizing, refer to NEC. Articles 215
and 310. In the absence of complete information to permit calculations, the voltage drop
should be physically measured.
Table 6, Control Power Line Sizing
Maximum Length, ft (m)
0 (0) to 50 (15.2)
50 (15.2) to 75 (22.9)
75 (22.9) to 120 (36.6)
Notes:
1.
Maximum length is the distance a conductor will traverse between the control power
source and the unit control panel.
2.
Panel terminal connectors will accommodate up to number 10 AWG wire. Larger
conductors will require an intermediate junction box.
The Unit On/Off switch located in the Unit Control Panel should be turned to the "Off"
position any time compressor operation is not desired.
Low Voltage Starters
Control wiring for low voltage starters is per the wiring diagram on page 16. If the optional
"Full Metering Display" has been ordered, the following section will apply.
Wiring for Optional Remote D3 Display
Remote mounted low voltage wye-delta and solid state
starters require field wiring to activate the optional full
metering display on the chiller's operator interface panel.
The wiring is from the D3 board in the starter to the
compressor controller and to the bias block; both located
in the compressor control panel.
Wiring for Optional D3 .
The location of the connections in the starter are shown to
the right.
Wiring Connection on Starter for Optional Display
14
Wire Size (AWG)
Maximum Length, ft (m)
12
120 (36.6) to 200 (61.0)
10
200 (61.0) to 275 (83.8)
8
275 (83.8) to 350 (106.7)
See Figure 4, Field
Wire Size (AWG)
6
4
3
Figure 3, Starter Panel
IOMM Starter
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Troubleshooting
