GEA Grasso - Page 49

Grasso
Refri
g
eration Division
GRASSO SYSTEM CONTROL
01.2004/1 638660E_chapter2.doc Chap. 2 - 13
2.7.2 Compressor motor alarms
2.7.2.1 ’Motor feedback’ alarm — start up of compressor motor takes too long
Output — compressor motor on
’Motor feedback’ signal equals 1
’Motor feedback’ timer active
’Time before motor feedback too long’
alarm generated
Figure 2.15, Compressor motor start without (A) and with (B) an alarm
A.. Normal case: Compressor motor start without an alarm.
B.. In case of an alarm: During the starting operation, the motor feedback signal is delayed for too long
and an alarm is generated.
•
If
(1) Output — compressor motor on equals 1
→
Then
(3)
Start ’Motor feedback’ timer
•
If
(1) Output — compressor motor on equals 1
and
•
If
(2) ’Motor feedback’ signal equals 0
and
•
If
(3)
’Motor feedback’ timer expired
→
Then
(4) ’Time before motor feedback too long’ alarm generated
2.7.2.2 ’Feedback from motor starter missing’ alarm
Output — compressor motor on
’Motor feedback’ signal equals 1
’Feedback from motor starter missing’
alarm generated
Figure 2.16, ’Feedback from motor starter missing’ alarm
•
If
(1) Output — compressor motor on
and
•
If
(2) ’Motor feedback’ signal equals 0
→
Then
(3) ’Feedback from motor starter missing’ alarm generated