Johnson Controls SABROE Unisab III Control Engineering Manual page 196

Set-up
Example: Set point 1 = 50°C: Cooling starts at 50°C and stops at (50-2) = 48°C.
Thermo pump
Output for activating thermo pump takes place at compressor start-up. No regulation is con-
nected to this function.
3-way-V
The 3-way-valve is used to control the three-way motor valve for oil cooling, which is regula-
ted according to oil temperature. The set point for this value is set in Control values/Oil/
Temperature/Control. Set point, neutral zone and proportional band can now be set. This reg-
ulator is normally not used but can be used if a valve with motor drive is fitted.
AKV (Screw compressor)
Direct regulation of HLI cooling with a pulse modulated AKV valve and a solenoid valve. The
HLI-AKV cooling outlet is activated by rising discharge temperature. The solenoid valve is acti-
vated when oil cooling is required and it remains active until the compressor stops. Within 6
seconds the AKV valve is pulse modulated corresponding to the regulator output signal.
The set point for discharge temperature is adjusted in the parameter picture Control values/
Discharge/Temperature/Control Set point 1. In the same picture Neutral zone and Proportion-
al band can be adjusted.
HLI 4-20 mA
Liquid injection oil cooling (LIOC) by means of a 4-20 mA output signal from Unisab III. Oil
cooling output is activated by rising discharge temperature. The regulator is a PID regulator.
The set point for discharge temperature is adjusted in the parameter picture Control values/
Discharge/Temperature/Control Set point 1. In the same picture Neutral zone and PID param-
eters can be adjusted.
Note: For SAB 193-233-283-355, HLI 2 output is activated when the volume slide is above
85%.
Example:
Set point 1 = 65°C
Neutral Zone = 4°C
Proportional Band = 30°C
Integral time = 10 sec.
Differential time = 0 sec.
The regulator keeps the discharge temperature between 63°C and 67°C.
Thermo pump internal
The Thermo pump function is activated when the compressor is running and the discharge
temperature is higher than 80°C. The set point for the thermo pump internal operation is set
in Control/Discharge/Temperature/Control/Set point 1. The Thermo pump function controls an
output for filling an internal compartment with liquid, which due to evaporation cools the top
covers. The filling rate is controlled by Unisab III and it depends on the status of two level
switches which indicate low and high level in the compartment.
Engineering manual - Unisab III 1.10
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