Engineering manual - UniSAB III 1.10.8
001930 en 2021.06
203/346
13: Economiser (screw compressor)
No
Yes
Select this function if the compressor is connected to an economiser. Thus the economiser is con-
nected/disconnected according to compressor operation. The connection is important for regulation of
the compressor volume ratio.
14: Eco low cap (screw compressors)
0 to 100%
If the actual slide capacity is higher than the set value, the economiser is connected. If the slide capacity
is the %-setting stated in the economiser
Neutral zone
below this value, the economiser is
disconnected.
15: Neutral zone
5-20%
This parameter shows in % how much capacity must be reduced from the setting in
eco low cap
to dis-
connect the economiser.
16: Eco high suct press
-100 to 100
°
C/R
With ECO operation a suction pressure value can be entered in
°
C/R. If the suction pressure of the
economiser is above this value, the solenoid valves connected in the economiser system will be closed.
Hysteresis is 2
°
C/R. In a combined ECO and HLI operation, the set value must not be above -20
°
C/R.
17: Unloading (reciprocating compr.)
Normal
Total
Additional steps
VSD Normal
VSD Total
See subsection
for more information about the step unloading strategy for reciprocat-
ing compressors with a different kind of coupling; with and without frequency drive.
Select
Normal
- in general - if the compressor is not equipped with frequency drive and Centa soft cou-
pling and if the compressor is not equipped with
total unload
mechanics or with
additional step
mechan-
ics. Select
Normal
for TCMO compressors not equipped with frequency drive.
Select
Total
for SMC compressors equipped with
total unload
mechanics.
When selecting
Total
the compressor still activates the first capacity steps during start-up - but during
operation (
Man/Auto/Remote
) it can run down to 0% capacity. In order to avoid too high oil temperature
in this operating mode, there is a 300 second time limit (timer no. 12
Total unload
). When this timer ex-
pires, the compressor stops.
Select
Additional steps
for SMC/HPC and CMO/HPO compressors equipped with
additional step
me-
chanics and with an extra solenoid valve for additional steps. SMC 112 and 116 have two solenoid
valves, one is mounted on digital output no. 9 (similar to other compressors with
Additional steps
) and
the other (valve B) is mounted on digital output no. 3.
Select
VSD Normal
for SMC and CMO compressors mounted with frequency drive (VSD) and Centa
soft coupling. This choice is made if the compressor should not be able to run totally unloaded. Never
select VSD Normal for compressors mounted with Rexnord coupling.
Summary of Contents for SABROE Unisab III Control
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