Johnson Controls SABROE Unisab III Control, Engineering Manual

Page: 235 / 348

Engineering manual - UniSAB III 1.10.8
001930 en 2021.06
235/346
Set-up
Should the measuring value reach -6.5 ° C/R, the counting interval will be 3 seconds. If the pressure is
still moving upwards and exceeds -4 ° C/R (the Pb limit) the timer will count in seconds. The resulting total
delay will range between 60 and 300 seconds and after this the compressor will start.
Example 2: Discharge pressure regulation has been selected on a reciprocating compressor. The
measured discharge pressure equals the set point. The compressor is running at 100% capacity.
Set point Sp = 30
° C/R
Nz = 2 ° C/R Pb = 5 ° C/R
Delay down = 30 sec
P band factor delay down = 3.
When the measured discharge pressure exceeds 31
° C/R, the timer Delay down will start counting with
an interval of 3 seconds (P band factor) each time the value in the display counts one down. If the pres-
sure steadies the timer will run for 3 x 30 = 90 seconds.
Should the measuring value reach 33.5 ° C/R, the counting interval will be 2 seconds. If the pressure is
still moving upwards and exceeds 36 ° C/R (the Pb limit) the timer will count in seconds.
The resulting total delay will range between 30 and 90 seconds and after this the compressor will disen-
gage one capacity stage.