JOHNSON CONTROLS
165
FORM 100.50-NOM12
ISSUE DATE: 04/02/2019
8
ANALOG INPUT OPERATION
This section describes the control operation of the 29
analog inputs. These inputs are used by the control to
monitor and respond to unit temperatures, pressures,
enthalpy, etc. The location of each of these connec-
tions on the IPU board is contained in Table 51 on page
132. Notice that the ID gives the jack connection des-
ignated as “J” and then the identifying number of the
connector, followed by a–and then the pin number of
the connector. For example, the SUPPLY AIR TEM-
PERATURE analog input would be found at J1-1. This
is connector J1–Pin 1. As the IPU board board is po-
sitioned in the control box the top row of the J series
connectors is the input, the middle row is the common,
and the bottom row is the 5VDC input to the sensor.
Also the pin in the right hand top corner is pin 1.
Temperature Sensors
The temperature sensors are all 10K Type III Thermis-
tors. The relationship between the temperature and the
voltage output and resistance is contained in Table 55
on page 165. The following analog input are of this
type: Supply Air Temperature, Heat Entering Temp,
Outside Air Temp, Return Air Temp, Suction Temp #1,
Suction Temp #2, Suction Temp #3, and Zone Temp.
Duct Pressure Transducer
The Duct Pressure Transducer is locatedin the return air
section of the unit. The purpose of the transducer is to
sense and convert the static pressure in the supply-side
of the duct to a 0 to 5VDC voltage. The DC voltage is
sent to the IPU board and compared against the duct
static press active setpoint. The transducer is factory
wired, but pneumatic tubing must be field supplied and
installed (refer to SECTION 2 – INSTALLATION). The
duct static pressure transducer measures differential
pressure between the pressure in the duct and atmo-
spheric pressure. When verifying transducer operation,
the technician must insert a tee in the pneumatic tubing
and connect a manometer to the tee to verify the pres-
sure being applied to the transducer. Once this pressure
is known, a comparison can be made of the duct pres-
sure vs. output VDC from the transducer. Table 56 on
page 166 shows the relationship between the pressure
applied to the duct pressure transducer and the output
voltage. The output is linear between 0" W.C. and the
SPAN. The “DUCT PRESS TRANSDUCER SPAN”
can be set to 1.25, 2.5 or 5" W.C.
SECTION 8 – SERVICE
TABLE 55 - TEMPERATURE SENSOR RESISTANCE
°F VOLTAGE RESISTANCE °C
-25 0.49 139,639 -30.6
-20 0.53 127,453 -28.9
-15 0.60 109,624 -26.1
-10 0.69 94,519 -23.34
-5 0.78 81,665 -20.55
0.0 0.88 70,750 -17.78
5 0.98 61,418 -15.00
10 1.10 53,426 -12.22
15 1.22 46,582 -9.44
20 1.35 40,703 -6.67
25 1.48 35,639 -3.89
30 1.62 31,269 -1.11
35 1.77 27,490 1.67
40 1.91 24,219 4.44
45 2.06 21,377 7.22
50 2.21 18,900 10.00
55 2.36 16,744 12.78
°F VOLTAGE RESISTANCE °C
60 2.51 14,681 15.56
65 2.66 13,216 18.33
70 2.80 11,771 21.11
75 2.94 10,502 23.89
80 3.08 9,388 26.67
85 3.21 8,404 29.45
90 3.33 7,537 32.22
95 3.45 6,770 35.0
100 3.56 6,090 37.78
105 3.66 5,487 40.56
110 3.76 4,951 43.34
115 3.85 4,475 46.11
120 3.94 4,050 48.89
125 4.02 3,671 51.66
130 4.09 3,332 54.44
135 4.16 3,029 57.22
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