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Device manual
3.7
Basic alarm type description
The controller has got three basic types of alarms called type A, type B and type C.
3.7a Alarm type A
Alarm at a limit value based on the setpoint SP.
Alarm at over-temperature if alarm setting
positive. Alarm at under-temperature if alarm setting
A1.A
is negative. At positive setting the alarm is
triggered if PV is bigger than SP +
negative setting the alarm is triggered if PV is smaller
than SP -A1.A. The algebraic sign of the alarm
value
A1.A
(over- or under-temperature).
The hysteresis defines a span between alarm state and
switching back to normal state. At positive setting of
A1.A
returning to normal state is at
SP +
A1.A
returning to normal state is at SP - A1.A+
3.7b Alarm type B
Alarm at a fixed limit value of PV.
If
AL.1
= 2, alarm is triggered if the value set at
A1.b
is reached or exceeded.
The hysteresis defines a span between alarm state
and switching back to normal state. Returning to
normal state is at
If
AL.1
= 4, alarm is triggered if the value set at
A1.b
is reached or dropped below.
The hysteresis defines a span between alarm state
and switching back to normal state. Returning to
normal state is at
3.7c Alarm type C
Alarm at leaving a band around the setpoint SP.
The lower half of the band is defined by
the higher one by
The value entered at
because the process variable PV has to be
smaller than SP -A1.C to trigger the alarm.
The value entered at
because the process variable PV has to be
bigger than SP +
The hysteresis defines a span between alarm
state and switching back to normal state. For the
lower band returning to normal state is at
SP -A1.C+
returning to normal state is at
SP +
A1.C.
At all three types (A, B, C) alarm is always triggered in case of sensor failure.
W. Bälz & Sohn GmbH & Co.
A1.A
only indicates the direction of effect
-
HY.1
. At negative setting of
A1.b
-
HY.1
.
A1.b
+
HY.1
.
A1.C.
.
A1.C
is always negative
A1.C.
is always positive
A1.C.
to trigger the alarm.
HY.1
. For the higher band
-
HY.1.
.
Koepffstraße 5
D-74076 Heilbronn
A1.A
is
. At
A1.A
Alarm type A
HY.1
.
Alarm type B
A1.C
,
Alarm type C
Telefon (07131) 1500-0
6490B / 6490B-y / 6590B
Telefax (07131) 1500-21
Page 15
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