JOHNSON CONTROLS
153
SECTION 9 – SERVICE AND TROUBLESHOOTING
Form 150.63-NM9
Issue date: 5/20/2021
9
Table 30 - Pressure Transducers
0-400 PSIG SUCTION
PRESSURE
TRANSDUCER
0-650 PSIG DISCHARGE
PRESSURE
TRANSDUCER
PRESSURE
PSIG
VOLTAGE
VDC
PRESSURE
PSIG
VOLTAGE
VDC
0 0.5 0 0.5
50 1.0 81.25 1.0
100 1.5 162.5 1.5
150 2.0 243.75 2.0
200 2.5 325 2.5
250 3.0 406.25 3.0
300 3.5 487.5 3.5
350 4.0 568.75 4.0
400 4.5 650 4.5
RED WIRE = 5 V, BLACK WIRE = 0 V, WHITE/
GREEN WIRE = SIGNAL
TEST POINTS:
Suction Pressure:
System 1:
....................................
Microboard J7-10 to J7-9
System 2:
....................................
Microboard J9-10 to J9-9
Discharge Pressure:
System 1:
....................................
Microboard J7-11 to J7-7
System 2:
....................................
Microboard J9-11 to J9-7
The I/O board connections for the Discharge Transduc-
ers:
System 1 discharge transducer
J7-6 = +5 VDC regulated supply to transducer.
J7-11 = VDC input signal to the microboard. See the
formula above for voltage readings that corre-
spond to specific discharge pressures.
J7-7 = +5 VDC return.
J7-2 = drain (shield connection = 0 VDC).
System 2 discharge transducer
J9-6 = +5 VDC regulated supply to transducer.
J9-11 = VDC input signal to the microboard. See the
formula above for voltage readings that correspond to
specific discharge pressures.
J9-7 = +5 VDC return
J9-2 = drain (shield connection = 0 VDC).
The suction transducers have a range from 0 psig to
400 psig (27.5 barg). The output will be linear from 0.5
VDC to 4.5 VDC over the 400 psig (27.5 barg) range.
The following is a formula that can be used to verify
the voltage output of the transducer. All voltage read-
ings are in reference to ground (unit case).
V = (Pressure in psig x .02) + .5
or
V = (Pressure in barg x .29) + .5
where V = DC voltage input to microboard
Pressure = pressure sensed by transducer
The following are the I/O board connections for the
Suction Transducer:
System 1 suction transducer
J7-5 = +5 VDC regulated supply to transducer.
J7-10 = VDC input signal to the microboard.
See the formula above for voltage readings
that correspond to specific suction pressures.
J7-9 = +5 VDC return.
J7-1 = drain (shield connection = 0 VDC).
System 2 suction transducer
J9-5 = +5 VDC regulated supply to transducer.
J9-10 = VDC input signal to the microboard.
See the formula above for voltage readings
that correspond to specific suction pressures.
J7-9 = +5 VDC return.
J7-11 = drain (shield connection = 0 VDC).
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