Johnson Controls SABROE UniSAB III User Manual

Engineering manual - UniSAB III 1.10.8
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001930 en 2021.06
Compressor control and surveillance
3.1.8 Regulation of reciprocating compressors
Reciprocating compressors are capacity regulated in stages by connection/disconnection of cylinders,
typically in pairs, through solenoid valves controlled by UniSAB III.
How fast the compressor loads/unloads stages is determined by the timers Delay up and Delay down,
which will start counting as soon as the value is outside the neutral zone. The regulator is allowed to
have a P Band of 0, which means that the stages are loaded in seconds as set.
If the P band is above 0, the delay times can be prolonged as long as the value is within the P band. The
P band is only relevant if the P band factors Delay up and/or Delay down are set in the picture P band
factor at a value above 1. See P band factor in section 6.5 Timers.
If the value is just outside the neutral zone and the P band factor Delay up is e.g. 10, counting will be
slow: “1 sec.” becomes 10 sec. If the value is just outside the P Band, counting will be speeded up, "1
sec." becomes 1 sec.
For reciprocating compressors connected to frequency converters see also the UniSAB III sequence
manual.

Johnson Controls SABROE UniSAB III Specifications

General

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