GEA Grasso Manual page 64

Grasso
Refrigeration Division
2.7.2.16 High discharge temperature alarm
The same alarm is applied for the intermediate temperature at the low pressure side of a two stage compressor.
This temperature is also called intermediate temperature LP (T
The discharge temperature alarm function is illustrated in the following diagram.
T Discharge temperature
dis
A.. Time characteristic of the
discharge temperature
1 = calculated value for the next
capacity step (in case of capacity
increase this line lies below the
actual value line)
2 = actual value
V.. Forced increase of the capacity
due too high discharge
temperature
B.. High discharge temperature
limitation active
T.. Limit timer active; After that this
timer has expired the capacity
control is enabled again and the
compressor capacity can be
decreased.
b.. Limit value for disabling capacity
decrease
f.. Limit value for forced increase of
capacity
W.. Warning limit
Al.. Alarm limit
ML W.. Warning active
ML A.. Alarm active
3.. Reset of the active alarm
Disch temp
Tdis hi alarm
High warning
<< Limit values 01
Chap. 2 - 28
Figure 2.32, High discharge temperature alarm
Disch temp:
Tdis hi alarm:
High warning:
>>
638660E_chapter2.doc
).
int
Line 1 is valid for single stage compressors only. In case of
a two stage compressor the ϕ value is used to determine
which capacity steps have to be blocked. For detailed
information is referred to chapter 2.7.3 'Specific control of
two stage piston compressors'.
Actual discharge temperature in °C
Alarm limit for high discharge temperature in °C
Enter the warning value as an offset to the alarm limit in K
GRASSO SYSTEM CONTROL
01.2004/1