9
Step 4 — Complete Electrical Connections
GENERAL — Verify that nameplate electrical requirements
match available power supply. Voltage at condenser must be
within the minimum and maximum shown in Tables 4A and
4B, and phases must be balanced within 2%. Contact local
power company for line voltage corrections. Never operate a
motor where a phase imbalance in supply voltage is greater
than 2%. Use the following formula to determine the percent-
age of voltage imbalance:
Example: Supply voltage is 240-3-60.
AB = 243 volts
BC = 236 volts
AC = 238 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 then 4 volts. To determine the percent-
age of voltage imbalance.
= 1.7%
This amount of phase imbalance is satisfactory since it is
below the maximum allowable 2%.
Condenser operation on improper line voltage or excessive
phase imbalance may be considered abuse and any resulting
damage may not be covered by Carrier warranty.
All wiring must be in accordance with NEC (National Elec-
trical Code) regulations or local codes.
CONNECTIONS — Refer to Tables 4A and 4B and Fig. 7 for
field wiring details.
MAIN POWER WIRING — Install field-supplied branch cir-
cuit fused disconnect(s) of a type that can be locked OFF or
OPEN. Disconnect(s) must be within sight from and readily
accessible from unit in compliance with NEC Article 440-14 or
local code. The units must have adequate overcurrent protec-
tion, fuses, or HACR (Heating, Air Conditioning, and Refrig-
eration) breakers according to the national and applicable local
codes. For field power connections, all main power wiring en-
ters the unit through a factory-punched access hole under the
control box. Attach power wires to power terminal block (or
the fan relay if not equipped with a power terminal block), to
the 3 power connections in the unit control box. Be sure to in-
stall a ground wire. See Fig. 7.
CONTROL CIRCUIT POWER WIRING — Connect 115-v
control wires to the 2 low-voltage connections at the control
power terminal block.
GENERAL WIRING NOTES — Factory options including
speed control, head pressure control, winter start control, fan
cycling, and electrical interlock, may affect wiring connec-
tions. Refer to Fig. 7-9 for typical unit wiring.
1. Power entry is at one end only.
2. Fan motors are thermally protected. All 3-phase motors
are protected against primary single-phasing conditions.
3. Replacement of factory wires must be with appliance
wiring material rated 105 C or its equivalent.
4. Factory wiring is in accordance with National Electrical
Code. Field modifications or additions must be in compli-
ance with all applicable codes.
09AZ Controls —
The 09AZV091-182 units are de-
signed to operate specifically with 30HXA chillers, using
R-134a refrigerant. Units with 8 fans have 2 direct controlled
(applied to optional variable speed), 4 refrigerant pressure and
2 ambient temperature controlled fans. Units with 10 fans have
2 direct controlled (applied to optional variable speed), 4 refrig-
erant pressure and 4 ambient temperature controlled fans. Units
with 12 fans have 2 direct controlled (applied to optional vari-
able speed), 6 refrigerant pressure and 4 ambient temperature
controlled fans.
Operation Sequence —
All condenser fans are al-
lowed to operate once a call for cooling comes from the chiller.
Direct fans will operate while refrigerant pressure and ambient
temperature control fans maintain refrigerant head pressure
based on existing refrigerant pressure and ambient temperature
conditions. Optional variable speed control will ramp direct fan
motor speed for improved low ambient performance.
VARIABLE SPEED FAN CONTROL — All units, when
ordered with fan head pressure control are furnished with the
number 1 condenser motor as a single-phase motor for use
with head pressure control. The optional factory-mounted
motor head pressure control contains a fan head pressure
control device activated by a pressure sensor. The kit controls
condenser-fan motor speed in response to the saturated con-
densing pressure.
% Voltage Imbalance = 100 x
max voltage deviation
from average voltage
Average voltage
Average Voltage =
243 + 236 + 238
3
=
717
3
= 239 volts
% Voltage Imbalance = 100 x
4
239
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility com-
pany immediately.
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