Carrier 30GT 015 - Page 4

FIELD CONNECTIBNS
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 Illi , q ,
u on line side of terminal block TBl (see Fig. 8).
2. Control Power - Bring separate source power (115 l-
60 or 230-l-50) into unit as shown in Fig. 5,6,7. This
supplies power for control circuit, compressor crank-
case heater and cooler heater. Connect incoming wires
to TB2 in unit controI box (Ll to m and L2 to m.
Neutral side must be connected to terminal [7j. 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 440-14, 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 instaIled in the chilled water line to prevent
unit from running when water is not circulating
through the cooler. This switch (no. HR8 1 LG005) 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
interlocked in the control circuit, between terminals
a and 161 (for flow switch), and [5! and 16j (for
auxiliary contacts) on TB2. See Fig. 8 for field wiring.
Unbalanced 3-Phase Supply Voltage - Never
operate a motor where a phase imbalance in supply volt-
age is greater than 2%. Use the following formula to
determine the % voltage imbalance:
% Voltage Imbalance
i’
= 100 x
max voltage deviation from average voltage
average voltage
Example: Supply voltage is 240-3-H).
A
B c
I
~
AB = 243 volts
BC = 236 volts
AC = 238 volts
MOTOR
__ .
243 + 236 •+ 238
^^_ .
Average Voitage =
3
= ZJY volts
Determine maximum deviation from average voltage:
(AB) 243 - 239 = 4 volts
(BC) 239 - 236 = 3 volts
(AC) 239 - 238 = 1 volt
Maximum deviation is 4 volts. Determine % voltage
imbalance:
4
o/G VoItage Imbalance z IO0 x m 1. 1 .~YG
This amuunt af phase imbalance is satisfactory as it is
below the maximum allowable 2$&
IMPORTANT: Contact your local electric utility
company immediateBy if the supply vohage phase
imbalance is more than 2%.
>‘,
‘i