GEA Grasso - Page 60

Grasso
Refri
g
eration Division
GRASSO SYSTEM CONTROL
Chap. 2 - 24 638660E_chapter2.doc 01.2004/1
2.7.2.12 Low oil differential pressure alarm
The oil differential pressure is monitored. In case the pressure becomes too low, an alarm is generated. The
alarm does not become active until the start up process has been completed and two separate delay times have
expired. The first delay time ’oil dif start’ becomes active directly after the start of the compressor motor. The
second delay time ’oil dif run’ becomes active as soon as during operation the oil differential pressure becomes
too low and the first delay time has expired. For more information see chapter 2.7.1 ’Oil system monitor of
piston compressor packages’.
The low oil differential pressure alarm function is illustrated in the following diagram.
∆P
oil
Oil differential pressure
A.. Time characteristic of the oil
differential pressure
W.. Warning limit
Al.. Alarm limit
ML W.. Warning active
ML A.. Alarm active
T1.. Delay time ’Oil dif start’
T2.. Delay time ’Oil dif run’
3.. Reset of the active alarm
Figure 2.28, Low oil differential pressure alarm
Oil dif press 
dPoil low alarm 
Low warning + 
Oil dif press: Actual oil differential pressure in bar
dPoil low alarm: Alarm limit for minimum oil differential pressure in bar
Low warning: Enter the warning value as an offset to the alarm limit in
<< Limit values 01 >> bar
Oil dif start 
Oil dif run 
Oil dif start: Alarm delay time during the start of the compressor
motor in s
Oil dif run: Alarm delay time during the normal operation of the
<< Timer values 01 >> compressor in s
) The sum of these timers may not exceed 60 seconds.