Bryant 551B Series Installation, Start-Up And Service Instructions Manual page 12

LEGEND
CUL — Canadian Underwriters' Laboratories
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
*Heaters are field installed only.
†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 volt-
age, heater kW will vary accordingly.
**Fuse or HACR circuit breaker.
NOTES:
1. In compliance with NEC requirements for multimotor and combina-
tion load equipment (refer to NEC Articles 430 and 440), the over-
current 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 percent
of voltage imbalance.
Table 3 — Thermostats
Manual Changeover
(Standard)
1 Heat/1 Cool
2 Heat/2 Cool
Auto. Changeover
(Standard)
1 Heat/1 Cool
2 Heat/2 Cool
Manual Changeover
(Electronic Setback)
1 Heat/2 Cool
Auto. Changeover
(Electronic Setback)
1 Heat/1 Cool
2 Heat/2 Cool
*Used with economizer.
†Used with 2-stage electric heat.
LEGEND
AHA — Adjustable Heat Anticipator
CC — Cooling Compensator
RC — 24-V Cooling
RH — 24-V Heating
Fig. 11 — Low-Voltage Connections With or
Without Economizer or Two-Position Damper
TYPE
TC — Thermostat-Cooling
TH — Thermostat-Heating
Factory Wiring
Factory Wiring
% Voltage Imbalance
max voltage deviation from average voltage
= 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 voltage imbalance.
% Voltage Imbalance = 100 x
This amount of phase imbalance is satisfactory as it is below the maxi-
mum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than
2%, contact your local electric utility company immediately.
3. 575-v units are CUL-approved only; electric heaters are not avail-
able for 575-v units.
Fig. 12 — Field Control Wiring Raceway
D. Accessory Installation
At this time, any required accessories should be installed on
the unit. Installation information can be found in the acces-
sory installation book.
Accessory Electric Heat
Each heater package consists of one or more electric heater
module kits and requires the correct single point kit. Refer to
Accessory Electric Heater and Single Point Box Installation
Instructions shipped with the heater for installation details.
E. Factory Installed Disconnect Switch
The optional disconnect switch is non-fused. The switch has
the capability of being locked in place for safety purposes.
—12—
average voltage
AB = 452 v
BC = 464 v
AC = 455 v
452 + 464 + 455
Average Voltage =
3
1371
=
3
= 457
7
457
= 1.53%