GEA Grasso Manual page 62

Grasso
Refrigeration Division
2.7.2.14 Low intermediate gas overheat alarm
The intermediate 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 'dTm alarm dly' becomes active as soon as the intermediate
gas overheat drops below its alarm limit value during the normal operation of the compressor.
The low intermediate gas overheat alarm function is illustrated in the following diagram.
∆T
Intermediate gas overheat
m
A.. Time characteristic of the
intermediate gas overheat
W.. Warning limit
Al.. Alarm limit
ML W.. Warning active
ML A.. Alarm active
T1.. Delay time 'dTm alarm dly'
3.. Reset of the active alarm
Intm dif temp
dTm low alarm
Low warning +
<< Limit values 01
dTo alarm dly
dTm alarm dly
Run.hours
<< Timer values 01
For GSC control of the refrigerant injection in the economiser (ECO system) the following settings are
recommended:
Limit values:
Timer values:
Chap. 2 - 26
Figure 2.30, Low intermediate gas overheat alarm
Intm dif temp:
dTm low alarm:
Low warning:
>>
dTo alarm dly:
dTm alarm dly:
Run.hours:
>>
dTm low alarm = 2.0 K / Low warning = 0.0 K
dTm alarm dly = 40 s
638660E_chapter2.doc
Actual intermediate gas overheat in K
Alarm limit for low intermediate 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
01.2004/1