GEA Grasso Manual page 49

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