Bryant 558F - Manual (Page 12)

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Table 2 — Electrical Data (cont)
LEGEND
*Heater capacity (kW) is based on heater voltage of 208 v, 240 v and 480 v.
Heaters are rated at 240 v and 480 v. If power distribution voltage to unit varies
from rated heater voltage, heater kW will vary accordingly. To determine heater
capacity at actual unit voltage, multiply 240 v or 480 v capacity by multipliers
found in table in Note 4.
†Fuse or HACR circuit breaker.
**Electric heaters are field installed.
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. The 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 percent of voltage
imbalance.
% Voltage Imbalance
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 voltage imbalance.
= 1.53%
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.
3. MCA calculation for 558F units with electric heaters over 50 kW = (1.25 x
IFM amps) + (1.00 x heater FLA).
4. Use the following table to determine heater capacity at actual voltage.
EXAMPLE: 34 kW (at 230 v) heater on 208 v
= 34.0 (.751 mult factor)
= 25.5 kW capacity at 208 v.
UNIT
558F
NOMINAL
VOLTAGE
(3 Ph, 60 Hz)
VOLTAGE
RANGE
COMPRESSOR
OFM IFM
POWER
EXHAUST
ELECTRIC
HEAT*
POWER SUPPLY
No. 1 No. 1A No. 2
Min Max RLA LRA RLA LRA RLA LRA Qty Hp
FLA
(ea)
Hp FLA FLA LRA kW FLA MCA MOCP†
300
208/230 187 253 20.7 156 20.7 156 47.1 245 6 0.5 1.7 10.0 28.0/28.0
— — — — 138/138 175/175
4.6 18.8 — — 143/143 175/175
— — 26/34 71/ 82 138/138 175/175
4.6 18.8 26/34 71/ 82 143/143 175/175
— — 42/56 117/135 181/170 200/175
4.6 18.8 42/56 117/135 187/176 200/200
— — 56/75 156/180 191/215 200/225
4.6 18.8 56/75 156/180 197/221 200/225
460 414 508 10.0 75 10.0 75 19.6 125 6 0.5 0.8 10.0 14.6
— — — — 64 80
2.3 6 — — 66 80
— — 32 39 67 80
2.3 6 32 39 70 80
— — 55 66 84 90
2.3 6 55 66 87 100
— — 80 96 114 125
2.3 6 80 96 117 125
FLA — Full Load Amps
HACR — Heating, Air Conditioning and Refrigeration
IFM
— Indoor (Evaporator) Fan Motor
LRA — Locked Rotor Amps
MCA — Minimum Circuit Amps
MOCP — Maximum Overcurrent Protection
NEC
— National Electrical Code
OFM — Outdoor (Condenser) Fan Motor
RLA — Rated Load Amps
= 100 x
max voltage deviation from average voltage
average voltage
AB = 452 v
BC = 464 v
AC = 455 v
Average Voltage = 452 + 464 + 455
3
=
1371
3
= 457
% Voltage Imbalance = 100 x
7
457
HEATER
RATING
VOLTAGE
ACTUAL HEATER VOLTAGE
200 208 230 240 380 440 460 480
240 0.694 0.751 0.918 1.000 — — — —
480 — — — — 0.626 0.840 0.918 1.000