Grasso
Refrigeration Division
GRASSO SYSTEM CONTROL
01
.200
4
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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
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