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Copyright 2008 TAC All Rights Reserved.
F-26159-5
Controller Output Scaling
In order to properly control the actuator, the output of the controller must be scaled
appropriately. Table-2 below illustrates the correct output which corresponds to the
electronic input of the transducer.
* Applies only to CP-8552.
CHECKOUT
4 to 20 mA Range
(CP-8551 and
CP-8552)
Note: The CP-8551 and CP-8552 4 to 20 mA span and start point potentiometers are not
field adjustable.
To check transducer operation:
1. Check for foreign material such as dirt or oil in the air supply. Also check for clogged filters.
Supply air contamination by dirt or oil is the most likely cause of malfunction.
2. Verify that the unit is mounted upright and wired correctly.
3. Verify that 20 psig (138 kPa) main air is present.
4. Verify with a digital multimeter that a 4 to 20 mAdc signal is present and of correct
polarity.
5. Adjust the input signal to 4 mA. Branch pressure should be 3 psig ± 1.0 (21 kPa).
6. Adjust the input signal to 20 mA. Branch pressure (direct acting) should be 15 psig
± 1.0 (103 kPa).
7. Unit is functional if correct pressures are indicated. Replace an inoperative transducer
with a functional unit.
Table-2 Electronic/Pneumatic Transducer Conversion Chart.
Electronic Input
Output
(PSI)
4-20
mA
6-9
Volts*
0-10
Volts*
3
4.00
6.00
0.00
4
5.33
6.25
0.83
5
6.67
6.50
1.67
6
8.00
6.75
2.50
7
9.33
7.00
3.33
8
10.67
7.25
4.17
9
12.00
7.50
5.00
10
13.33
7.75
5.83
11
14.67
8.00
6.67
12
16.00
8.25
7.50
13
17.33
8.50
8.33
14
18.67
8.75
9.17
15
20.00
9.00
10.00