Johnson Controls SABROE UniSAB III User Manual

Engineering manual - UniSAB III 1.10.8
116/346
001930 en 2021.06
Compressor control and surveillance
Alarm surveillance
During start the following alarms are delayed:
Low oil pressure 45 sec.
High filter diff. pressure 600 sec.
Low superheat 300 sec.
High superheat 300 sec.
Low/high oil temperature
300 sec.
The delayed alarms are described in section 6.5 Timers.
Stopping sequence
When a SAB 193-233-283-355 compressor stops, UniSAB III will attempt to move the capacity slide be-
low 5% position. The solenoid valves for decreasing capacity and Vi position are activated for maximum
300 seconds. If the capacity slide is not below 5% within the 300 seconds a Capacity error shutdown will
be issued.
Balance piston for SAB 355
For SAB 355, the AUX output is dedicated for control of the balance piston. Choose the AUX output to
be activated At max. cap. in the menu Compressor control – user functions and set the Signal high limit
to 70% referring to slide capacity.
3.3.20 SABCube 109, 133 and 159
The SABCube compressors are frequency-regulated screw compressors without capacity slide but with
automatic Vi-control. The compressors have no oil pump.
Starting sequence
Once the compressor has received permission to start, UniSAB III will send a start signal to the fre-
quency converter and to the internal water cooling pump.
When the compressor starts up, the SSSTV valve will close in order to reduce the internal suction pres-
sure and quickly increase the oil pressure. When the timer Start unload has run out the Start-up limiter is
activated and the timer Max. start-up time is started.
The SSSTV valve is kept closed until the oil pressure is above the low alarm curve Y + a Neutral zone
(NZ
oil,rel
) and the suction pressure is below high alarm limit for internal suction pressure - a Neutral zone
(NZ
suct,int
).
Speed will remain at 1,000 rpm until the oil pressure is above the low alarm curve Y and the internal suc-
tion pressure is below high alarm limit for internal suction pressure.
If the timer Max. start-up time runs out before the oil and suction pressure is inside the alarm limits, the
compressor is stopped with a shutdown.
After this forced start-up period where oil and suction pressures are inside the alarm limits, the compres-
sor is now in normal operation. The SSSTV limiters for High torque, high internal suction pressure and
low oil pressure will now be active too.
The default setting for timer Start unload is 15 seconds and for Max. start-up time it is 600 seconds.

Johnson Controls SABROE UniSAB III Specifications

General

Brand	Johnson Controls
Model	SABROE UniSAB III
Category	Control Systems
Language	English