Calibration Procedure For Position Transmitters; Capacity Slide Adjustment, Manual Vi; Capacity Slide Adjustment, Auto Zero Point; Capacity Slide Adjustment, Auto Vi - Johnson Controls SABROE UniSAB III Engineering Manual

ALU tube
Fig. 33: Long-stroke capacity rod transmitter for SAB 193 H-233 H-283 H-355 H.
7.5.1

Calibration procedure for position transmitters

The procedure for calibrating minimum and maximum position is the same for all transmitter types. In
the following, the procedure will be described for compressors with manual Vi, compressors with auto-
matic zero point and finally compressors with automatic Vi adjustment. Calibration of the specific trans-
mitter type is described in subsections 7.5.6 to 7.5.13. Software calibration is described in subsection
7.5.14
7.5.2

Capacity slide adjustment, manual Vi

Note: The capacity transmitter must be adjusted every time the manual adjustable Vi position is
changed.
Start the compressor in Manual and make sure that the capacity slide is in minimum. Adjust the mini-
mum position on the transmitter. Now bring the capacity slide to its maximum position (i.e. when the cur-
rent consumption is no longer rising) and adjust the maximum position on the transmitter. Return the
slide to minimum and check.
To make sure that the slide is in maximum physical position (UniSAB III does not allow the capacity but-
ton to be activated after reaching 100% indication in the display) it is recommended to set Cap. 100%
Adjustm. at -10% after 100% calibration of the transmitter has been completed. See subsection 7.5.14
The slide indication in the display must now be 90%. If capacity can be increased further either automati-
cally by UniSAB III or by pressing the
(Note that it may be necessary to check if power consumption increases as it cannot be assumed that
the transmitter can supply more than 20 mA.) If capacity could be increased, cf. above, calibrate the
slide again from point 1 but keep -10% in Cap. 100 Adj.
Reset Cap. 100 Adj to what it was before calibration or adjust it until capacity shows 100%.
7.5.3

Capacity slide adjustment, auto zero point

For SAB 202 compressors with automatic zero point setting, there are two applicable methods to ensure
that the automatic zero point setting does not influence the adjusting of the transmitter minimum
position.
• Do not adjust the minimum position on the transmitter until the compressor has stopped and the
slide is in mechanical zero.
• Start the compressor in Manual and disconnect the automatic zero point setting while adjusting
the minimum position on the transmitter. Do this by setting Manual zero = 0.1 in the picture Set-
up/Configuration/Compressor block.
Adjust the minimum position on the transmitter. Now bring the capacity slide to its maximum position (i.
e. when the current consumption is no longer rising) and adjust the maximum position on the transmitter.
Return the slide to minimum and check.
Remember to set Manual zero = 0.0 as soon as the capacity slide adjustment is accomplished. It is im-
portant that the compressor only runs for a short period of time when the automatic zero point setting is
disconnected.
7.5.4

Capacity slide adjustment, auto Vi

To adjust the movement of the capacity slide, the Vi slide must be in minimum position. The Vi slide is
brought to minimum the following way: Start the compressor in Manual, select Control/values/Capacity/
Vi slide position/Control. The following picture will appear:
3
2 1
F2 /CAP. UP button, the slide has not yet been calibrated correctly.
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Calibration
Engineering manual - UniSAB III 1.10.8
001930 en 2021.06