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Table 2 — electrical data (cont) – Bryant 558F User Manual

Page 12

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12

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