Johnson Controls SABROE Unisab III Control Engineering Manual page 166

Set-up
Hot water temperature is measured by a Pt 100 sensor in the water output of the condenser.
Set point is set in the picture Control values/ Process temp./Process out temp./Control.
Ext. cool At this stage it is possible to connect an external 4-20 mA transducer as cooling
function, i.e. at a rising signal the compressor will load capacity. Additionally, set Function to
Ext.inp.signal in picture Setup/Configuration/External input. The points 4 mA and 20 mA must
be set as minimum (4 mA) and maximum (20 mA) values of the sensor. Select Control val-
ues/User/User Input 1/Control and enter regulator set point, neutral zone and prop. band.
See also section 3.1.1. Control mode set-up.
Ext. heat At this stage it is possible to connect an external 4-20 mA transducer as heating
function, i.e. at a falling signal the compressor will load capacity. Additionally, set Function to
Ext.inp.signal in picture Setup/Configuration/External input. The points 4 mA and 20 mA must
be set as maximum (20 mA) and minimum (4 mA) values of the sensor. Select Control val-
ues/ User/User Input 1/Control and enter regulator set point, neutral zone and prop. band.
See also 3.1.1. Control mode set-up.
3: Capacity controller
I
PID
Select PID for special applications where a change in the cooling requirement must be met by
a fast change in capacity. Select I for normal refrigeration plants. See also section 3.1.1. Con-
trol mode set-up.
4: Auto start
No
Yes
If selecting Yes, the compressor will start by itself in Auto/Remote depending on what is re-
quired. Regulation is now automatic. If selecting No, the compressor must be started manual-
ly even though it is in Auto/Remote. During operation the compressor regulates automatically.
5: Auto stop
No
Yes
If selecting Yes, the compressor will stop automatically at minimum capacity by decreasing
demand. If selecting No, the compressor must be stopped manually even if Auto or Remote
has been selected in Setup/Compr. Control, Mode.
6: Cold store
No
Yes
Choosing this function affects the way the Multisab system starts and regulates the compres-
sors in a common system. See detailed description in section 3.5. Compressor control - user
functions.
7: Climate compensation
No
Yes
If the compressor is used for water/brine cooling or water heating, the flow temperature can
be raised or reduced depending on the outside temperature. An extra 4-20 mA temperature
Engineering manual - Unisab III 1.10
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