GEA Grasso - Control Sequence

Grasso
Refri
g
eration Division
GRASSO SYSTEM CONTROL
01.2004/1 638660E_chapter2.doc
2. Control sequence 1
2.1 Overview of the operating modes 1
2.2 Explanation of symbols and characters used 2
2.3 General starting conditions 2
2.3.1 Start to start timer (anti- recycle timer) 3
2.3.2 Stop to start timer 3
2.4 Start up sequence 4
2.4.1 Single stage and booster piston compressor packages 4
2.4.2 Two stage piston compressor packages 5
2.5 Switch off sequence 6
2.5.1 Switching off sequence in the normal case for booster, single- and two stage compressor packages 6
2.5.2 Switching off sequence in case of an alarm for booster, single- and two stage compressor packages 6
2.5.3 Switching off sequence in the normal case and in case of an alarm with ’Pump down’ 7
2.6 Compressor control 8
2.6.1 Capacity control 8
2.6.2 Mode of operation of the capacity controller 8
2.7 Safety control (Alarms, warnings and limitations) 10
2.7.1 Oil system monitor of piston compressor packages 11
2.7.1.1 Switching sequence in the normal case 11
2.7.1.2 Switching sequence in case of too low oil differential pressure alarm during running 12
2.7.2 Compressor motor alarms 13
2.7.2.1 ’Motor feedback’ alarm — start up of compressor motor takes too long 13
2.7.2.2 ’Feedback from motor starter missing’ alarm 13
2.7.2.3 Motor current limitation 14
2.7.2.4 High motor current alarm 15
2.7.2.5 Low suction pressure limitation 16
2.7.2.6 Low and high suction pressure alarm 17
2.7.2.7 Low external temperature limitation (Chiller outlet temperature) 19
2.7.2.8 Low external temperature alarm (Chiller outlet temperature) 20
2.7.2.9 High discharge pressure limitation 21
2.7.2.10 High discharge pressure alarm 22
2.7.2.11 High intermediate pressure alarm 23
2.7.2.12 Low oil differential pressure alarm 24
2.7.2.13 Low suction gas overheat alarm 25
2.7.2.14 Low intermediate gas overheat alarm 26
2.7.2.15 High discharge temperature limitation 27
2.7.2.16 High discharge temperature alarm 28
2.7.2.17 Start limitation based on too low oil temperature 29
2.7.2.18 Low and high oil temperature alarm 30
2.7.2.19 Low and high compressor motor speed alarm (for frequency control only) 31
2.7.3 Specific control of two stage piston compressors 32
2.7.3.1 Intermediate cooling systems with and without economiser 32
2.7.3.2 Monitoring of the intermediate pressure, intermediate temperature and discharge temperature 33
2.7.3.3 Pull down operation during start up and during normal operation of the compressor 34
2.7.3.4 Fast pull down 35
2.7.3.5 Economiser control 35