nVent RAYCHEM 1244-0006829, Operating And Installation Manual

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The ramp function is cancelled in the event of a probe break or
in manual mode. The outputs react in the same manner as for an
overrange/underrange (configurable).
7.4 Limit comparators
Limit comparators can be used to monitor the process value
against defined alarm limits. The way the limit comparators
operate can be configured by the user (lk1 to lk8). Once an alarm
limit (alarm set point) is exceeded, an alarm signal can be ouput
or an internal function can be initiated.
There are 2 limit comparators available (LC1, LC2). The switching
differential HySt can be user defined and will always be
symmetrical in relation to the alarm set point (AL).
Alarm value AL relative to the set point value w
The limit comparator functions lk1 to lk6 monitor the process
value x for an alarm value AL which is relative to the set point
value w. This means that if the set point is changed the absolute
alarm values will shift as well.
2 k l 1 k l
4 k l 3 k l
w
1
AL
x
HySt
0
AL
HySt
0
1
w
x
w
1
AL
x
HySt
0
AL
HySt
1
0
w
x
6 k l 5 k l
AL
w
1
x
HySt
0
AL
HySt
1
0
w
x
8 k l 7 k l
AL
1
x
HySt
0
AL
HySt
1
0
x