Bryant 548F Installation, Start-Up And Service Instructions Manual page 12

LEGEND
FLA — Full Load Amps
HACR — Heating, Air Conditioning and Refrigeration
IFM — Indoor-Fan Motor
LRA — Locked Rotor Amps
MCA — Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection
NEC — National Electrical Code
OFM — Outdoor-Fan Motor
RLA — Rated Load Amps
*Heater capacity (kW) is based on heater voltage of 208 v, 240 v, or 480 v. If
power distribution voltage to unit varies from rated heater voltage, heater kW
will vary accordingly.
†Used to determine minimum disconnect per NEC.
**Heaters are field installed only.
††Fuse or HACR circuit breaker.
||Electrical disconnect cannot be used if electric heater is installed. (Applies to
any line with an FLA greater than or equal to 80.)
NOTES:
1. In compliance with NEC requirements for multimotor and combination load
equipment (refer to NEC Articles 430 and 440), the overcurrent protective
device for the unit shall be fuse or HACR 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.
LEGEND FOR TABLES 2A AND 2B
% Voltage Imbalance
= 100 x
Example: Supply voltage is 460-3-60.
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
This amount of phase imbalance is satisfactory as it is below the maximum
allowable 2%.
IMPORTANT:
tact your local electric utility company immediately.
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max voltage deviation from average voltage
average voltage
AB = 452 v
BC = 464 v
AC = 455 v
452 + 464 + 455
Average Voltage =
1371
=
3
= 457
7
457
= 1.53%
If the supply voltage phase imbalance is more than 2%, con-
3