FIELD
1. Main Power
Bring wires from the fused disconnect
switch through hole in bottom rail of unit to control
box (Fig. 5, 6, 7) and connect to terminals
,
q
,
on line side of terminal block
(see Fig. 8).
2. Control Power
Bring separate source power
or 230-l-50) into unit as shown in Fig.
This
supplies power for control circuit, compressor crank-
case heater and cooler heater. Connect incoming wires
to TB2 in unit
box
to
and L2 to
Neutral side must be connected to terminal
In the
auxiliary power supply a field-supplied disconnect
with 7-amp circuit protection must be provided to
accommodate crankcase heater and cooler heater
cable.
To comply with NEC Article
the disconnect
must be located within sight from and readily acces-
sible from unit.
IMPORTANT: To ensure power to the heaters,
make sure auxiliary power to unit is always on
(except for servicing or prolonged shutdown).
A toggle switch (marked SW on the label diagram) allows
the control circuit to be manually disconnected when
necessary. This switch does not affect the crankcase
heater and cooler heater cable.
3. Control Circuit Interlocks
An accessory flow switch
may be
in the chilled water line to prevent
from running when water is not circulating
through the cooler. This switch (no.
1
is
available as an accessory from Service Parts Center, or
equivalent can be field supplied. Also, it is recom-
mended that auxiliary contacts for the chilled water
pump starter be installed in the control circuit as
additional protection against unit operation when
pump is not running. These items should be electrically
in the control circuit, between terminals
and
(for flow switch), and
and
(for
auxiliary contacts) on TB2. See Fig. 8 for field wiring.
Unbalanced
Supply Voltage
Never
operate a motor where a phase imbalance in supply volt-
age is greater than
Use the following formula to
determine the
voltage imbalance:
Voltage Imbalance
=
x
max voltage deviation from average voltage
average voltage
Example: Supply voltage is
A
c
AB = 243 volts
236 volts
AC = 238 volts
M O T O R
__ .
243 236 •+ 238
.
Average
3
volts
Determine maximum deviation from average voltage:
243 239 = 4 volts
(BC) 239 236 = 3 volts
(AC) 239 238 = 1 volt
Maximum deviation is 4 volts. Determine
voltage
imbalance:
4
Imbalance
This
phase imbalance is satisfactory as it is
below the maximum allowable
IMPORTANT: Contact your local electric utility
company
if the supply
phase
imbalance is more than
