GEA Grasso - Page 56

Grasso
Refri
g
eration Division
GRASSO SYSTEM CONTROL
Chap. 2 - 20 638660E_chapter2.doc 01.2004/1
2.7.2.8 Low external temperature alarm (Chiller outlet temperature)
In case of Chiller application this alarm is used as frost protection of the evaporator.
The low external temperature alarm function is illustrated in the following diagram.
T
ext
External temperature
A.. Time characteristic of the external
temperature
V.. Forced reduction of the capacity
due too low external temperature
B.. Low external 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
increased.
b.. Limit value for disabling capacity
increase
f.. Limit value for forced reduction of
capacity
W.. Warning limit
Al.. Alarm limit
ML W.. Warning active
ML A.. Alarm active
3.. Reset of the active alarm
Figure 2.24, Low external temperature or Chiller outlet temperature alarm
External temp 
Text low alarm 
Low warning + 
External temp: Actual external temperature in °C
Text low alarm: Alarm limit for minimum external temperature in °C
Low warning: Enter the warning value as an offset to the alarm limit in K
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