Bryant 548F Manuel d'utilisateur télécharger pdf (Page 12)

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LEGEND FOR TABLES 2A AND 2B

LEGEND

*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.

% Voltage Imbalance

Example: Supply voltage is 460-3-60.

AB = 452 v

BC = 464 v

AC = 455 v

= 457

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%.

IMPORTANT:

If the supply voltage phase imbalance is more than 2%, con-

tact your local electric utility company immediately.

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

= 100 x

max voltage deviation from average voltage

average voltage

Average Voltage =

452 + 464 + 455

1371

457

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Bryant 548F Manuel d'utilisateur Page 12

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