GEA Grasso Manual page 61

Grasso
Refrigeration Division
2.7.2.13 Low suction gas overheat alarm
The suction gas overheat is monitored. In case this overheat becomes too low, an alarm is generated. This alarm
does not become active until the start up process of the compressor has been completed and an additional delay
time has expired. The delay time 'dTo alarm dly' becomes active as soon as the suction gas overheat drops below
its alarm limit value during the normal operation of the compressor.
The low suction gas overheat alarm function is illustrated in the following diagram.
∆T
Suction gas overheat
o
A.. Time characteristic of the suction
gas overheat
W.. Warning limit
Al.. Alarm limit
ML W.. Warning active
ML A.. Alarm active
T1.. Delay time 'dTo alarm dly'
3.. Reset of the active alarm
Suct dif temp
dTo low alarm
Low warning +
<< Limit values 01
dTo alarm dly
dTm alarm dly
Run.hours
<< Timer values 01
For GSC control of refrigeration injection in the evaporator the following settings are recommended
(DX Chiller only):
Limit values:
Timer values:
01.2004/1
Figure 2.29, Low suction gas overheat alarm
Suct dif temp:
dTo low alarm:
Low warning:
>>
dTo alarm dly:
dTm alarm dly:
Run.hours:
>>
dTo low alarm = 2.0 K / Low warning = 0.0 K
dTo alarm dly = 40 s
638660E_chapter2.doc
Actual suction gas overheat in K
Alarm limit for minimum suction gas overheat in K
Enter the warning value as an offset to the alarm limit in K
Alarm delay time for low suction gas overheat in s
Alarm delay time for low intermediate gas overheat in s
Running hours in h
GRASSO SYSTEM CONTROL
Chap. 2 - 25