GEA Grasso - Page 41

Grasso
Refri
g
eration Division
GRASSO SYSTEM CONTROL
01.2004/1 638660E_chapter2.doc Chap. 2 - 5
2.4.2 Two stage piston compressor packages
Starting conditions fulfilled
Output — compressor motor on
Feedback — compressor motor on equals 1
’Motor feedback’ timer active
Unloaded start
Release of capacity control system
Release of start up with ’Pull down’
Pressure ratio OK
Figure 2.5, Start up sequence for two stage piston compressor package
•
If
(1) Starting conditions fulfilled
→
Then
(2) Set output — compressor motor on
→
Then
(4) Start ’Motor feedback’ timer
→
Then
(5) Set unloaded start
•
If
(3) Feedback — compressor motor on equals 1
→
Then
(4) Stop ’Motor feedback’ timer
•
If
(5) Unloaded start ended
→
Then
(7) Release start up with ’Pull down’
•
If
(8) Pressure ratio OK
→
Then
Reset the actuating signal (7)
→
Then
(6) Release of capacity control system