11
AB = 452 v
BC = 464 v
AC = 455
Determine maximum deviation from average voltage:
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine percent of voltage imbalance:
% Voltage Imbalance = 100 x
= 1.53%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
Unit operation on improper line voltage or excessive phase imbal
-
ance may be considered abuse and any resulting damage may not
be covered by Carrier warranty.
All wiring must be in accordance with local or NEC (National
Electrical Code) regulations.
POWER WIRING
The units must have adequate overcurrent protection, fuses, or
HACR (Heating, Air Conditioning and Refrigeration) breakers,
according to the national and applicable local codes.
For field power connections, all main power wiring enters the unit
through a factory-punched access hole under the control box. At
-
tach power wires to the power connections on the main power ter
-
minal block in the unit control box. Be sure to install a ground
wire.
CONTROL WIRING
All units require an accessory thermostat package to complete the
unit control system. For a room-mounted thermostat, the
thermostat may be mounted in an appropriate location in the
conditioned space. Route the wires from the thermostat to the low
voltage connection of the control box. Connect wires to the low
voltage terminal block. See Fig. 10. The fan switch on the
thermostat will control fan operations.
FREEZE PROTECTION THERMOSTAT
A freeze protection thermostat is standard and factory installed.
Average Voltage = 452 + 464 + 455
3
=
1371
3
= 457
IMPORTANT: If supply voltage phase imbalance is more than
2%, contact your local electric utility company immediately.
7
457