67
Table 52 — Pressure (psig) vs. Voltage Drop Values for Suction Pressure Transducers
MAJOR SYSTEM COMPONENTS
General —
The 48/50PG single-package rooftop units con-
tain the ComfortLink™ electronic control system that monitors
all operations of the rooftop. The control system is composed
of several main control components and available factory-
installed options or field-installed accessories as listed in sec-
tions below. See Fig. 14-19 for the control and power schemat-
ics. Figures 20 and 21 show the layout of the control box, unit,
and thermistor and transducer locations.
Main Base Board (MBB) — See Fig. 22 and Table 53.
The MBB is the center of the ComfortLink control system. It
contains the major portion of the operating software and con-
trols the operation of the unit. The MBB continuously monitors
input/output channel information received from its inputs and
from the Economizer Control Board (ECB). The MBB re-
ceives inputs from thermistors and transducers. The MBB also
receives the Current Sensor inputs for compressors and other
discrete or digital inputs. The MBB reads space temperature
(SPT) from either a T-55, T-56 or T-58 device and space tem-
perature offset (SPTO) from a T-56 device. See Field-Installed
Accessories section on page 82. The MBB controls 9 relays.
NOTE: The Main Base Board (MBB) has a 3-position instance
jumper that is factory set to ‘1’. Do not change this setting.
Economizer Control Board (ECB) — The ECB con-
trols the economizer actuator. See Fig. 23 and Table 54. The
control signal from the ECB uses either the MFT
(Multi-Function Technology) communication protocol or a 4 to
20 mA output signal as defined by the configuration
Configuration
→
ECON
→
E.CTL. The ECB has inputs for
Indoor Air Quality (IAQ), Outdoor Air Quality (OAQ), and
enthalpy. It also controls two power exhaust outputs.
By digitally communicating with the ECB, the economizer
actuator is able to provide the damper position and diagnostic
information to the ComfortLink controller. The damper
position is displayed at Outputs
→
ECON
→
EC.AP. Diagnostic
information is displayed via Alert T414. More information
about these alarms is contained in the Alarms and Alerts
section.
NOTE: The Economizer Control Board (ECB) has a
4-position DIP switch that is factory set to ON (towards the
center of the board). Do not change this setting.
Integrated Gas Control (IGC) Board — The IGC
is provided on gas heat units. See Table 55 and Fig. 24. The
IGC controls the direct spark ignition system and monitors the
rollout switch, limit switch, and induced-draft motor Hall
Effect switch. The IGC is equipped with an LED (light-
emitting diode) for diagnostics. See the Troubleshooting
section for more information.
Low Voltage Terminal Strip (TB2) — This circuit
board provides a connection point between the major control
boards and a majority of the field-installed accessories. See
Fig. 25 and Table 56. The interface connection for the Carrier
Comfort Network® (CCN) communication and interface con-
nection for the Local Equipment Network (LEN) communica-
tions are also located on the low voltage terminal strip.
PRESSURE
(psig)
VOLTAGE
DROP (V)
PRESSURE
(psig)
VOLTAGE
DROP (V)
PRESSURE
(psig)
VOLTAGE
DROP (V)
PRESSURE
(psig)
VOLTAGE
DROP (V)
0 0.465 68 1.135 136 1.804 204 2.474
2 0.485 70 1.154 138 1.824 206 2.493
4 0.505 72 1.174 140 1.844 208 2.513
6 0.524 74 1.194 142 1.863 210 2.533
8 0.544 76 1.214 144 1.883 212 2.553
10 0.564 78 1.233 146 1.903 214 2.572
12 0.583 80 1.253 148 1.922 216 2.592
14 0.603 82 1.273 150 1.942 218 2.612
16 0.623 84 1.292 152 1.962 220 2.631
18 0.642 86 1.312 154 1.982 222 2.651
20 0.662 88 1.332 156 2.001 224 2.671
22 0.682 90 1.351 158 2.021 226 2.690
24 0.702 92 1.371 160 2.041 228 2.710
26 0.721 94 1.391 162 2.060 230 2.730
28 0.741 96 1.410 164 2.080 232 2.749
30 0.761 98 1.430 166 2.100 234 2.769
32 0.780 100 1.450 168 2.119 236 2.789
34 0.800 102 1.470 170 2.139 238 2.809
36 0.820 104 1.489 172 2.159 240 2.828
38 0.839 106 1.509 174 2.178 242 2.848
40 0.859 108 1.529 176 2.198 244 2.868
42 0.879 110 1.548 178 2.218 246 2.887
44 0.898 112 1.568 180 2.237 248 2.907
46 0.918 114 1.588 182 2.257 250 2.927
48 0.938 116 1.607 184 2.277 252 2.946
50 0.958 118 1.627 186 2.297 254 2.966
52 0.977 120 1.647 188 2.316 256 2.986
54 0.997 122 1.666 190 2.336 258 3.005
56 1.017 124 1.686 192 2.356 260 3.025
58 1.036 126 1.706 194 2.375 262 3.045
60 1.056 128 1.726 196 2.395 264 3.065
62 1.076 130 1.745 198 2.415 266 3.084
64 1.095 132 1.765 200 2.434 268 3.104
66 1.115 134 1.785 202 2.454 270 3.124
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