7 Configuration level
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7.4 Limit comparators
Limit comparators (threshold monitors, limit contacts) can be used to
monitor the limit comparator process value against a fixed alarm value
or an alarm value depending on the limit comparator set point value.
When an alarm value is exceeded, a signal can be output or an internal
controller function initiated.
2 limit comparators are available (LC1, LC2).
Limit comparators can have different switching functions (lk1 to lk8).
The switching differential HySt can be set and is, in all cases,
symmetrical in relation to the alarm value (AL).
Alarm value AL relative to set point value w
The limit comparator functions lk1 to lk6 monitor the process value x
for an alarm value AL to be set, the absolute value depending on set
point value w.
lk1 lk2
lk3 lk4
w
1
AL
x
HySt
0
AL
HySt
0
1
w
x
w
1
AL
x
HySt
0
AL
HySt
1
0
w
x
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