Carrier WeatherMaster 50HCQA04, Service And Maintenance Instructions, Page: 63 / 98

63
Legend and Notes for Tables 47--58
LEGEND
C.O. --- Convenience outlet
DD --- Electric Drive X13 Motor
DISC --- Disconnect
FLA --- Full load amps
IFM --- Indoor fan motor
LRA --- Locked rotor amps
MCA --- Minimum circuit amps
P.E. --- Power exhaust
UNPWRD C.O. --- Unpowered Convenience outlet
NOTES :
1. In compliance with NEC requirements for multimotor and combina-
tion load equipment (refer to NEC Articles 430 and 440), the
overcurrent protective device for the unit shall be fuse or HACR
breaker. Canadian units may be fuse or circuit breaker.
2. Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance in supply voltage
is greater than 2%. Use the following formula to determine the
percentage of voltage imbalance.
% Voltage Imbalance = 100 x
max voltage deviation from average voltage
average voltage
Example: Supply voltage is 230-3-60
AB = 224 v
BC = 231 v
AC = 226 v
Average Voltage =
(224 + 231 + 226)
=
681
3 3
= 227
Determine maximum deviation from average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance = 100 x
4
227
= 1.76%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT : If the supply voltage phase imbalance is more than
2%, contact your local electric utility company immediately.