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4.4.
Alarms
4.4.1.
Generic alarms AL1...AL8
Generic alarms AL1...AL8 can be of 4 main types, shown
below:
Normal absolute alarm
(AL.1 inverse and absolute, AL.2 direct and absolute).
Two alarm thresholds are set, AL.1 (lower threshold) and
AL.2 (upper threshold), which correspond to two hysteresis
values, Hy.1 (positive) and Hy.2 (negative). The alarm is
triggered when the measured value remains below AL.1 or
greater than AL.2 for the set activation delay times.
The alarm condition stops when the measured value is
greater than AL.1 + Hy.1, or is less than AL.2 - Hy.2. This
avoids repeated alarms caused by slight variations in the
measured value.
Any alarm signal at startup, when the equipment is not in
normal operation, can be avoided by disabling it when pow-
er is turned on.
Symmetrical absolute alarm
A single AL.1 alarm threshold and a single Hy.1 hysteresis
value are set.
With the direct alarm setting, the alarm is triggered when
the measured value is less than AL.1 - Hy.1 or greater than
AL.1 + Hy.1 for the set delay activation time.
With the inverse alarm setting, the alarm is triggered when
the measured value is greater than AL.1 - Hy.1 or less than
AL.1 + Hy.1 for the set delay activation time.
Normal alarm for the reference variable
A single hysteresis value Hy.2 (negative), an alarm threshold
AL.2 and the value to which it relates are set. The previous
alarm threshold (in this case AL.1) is used as the relative
value. With the direct alarm setting, the alarm is triggered
when the reference value (A2.r) is greater than AL.1 + AL.2
for the set delay activation time. The alarm condition stops
when the measured value is less than AL.1 + AL.2 - Hy.1.
With the reverse alarm setting, the alarm is triggered when
the measured value (A2.r) is less than AL.1 + AL.2 - Hy.1for
the set delay activation time. The alarm condition stops
when the measured value exceeds AL.2 + AL.1.
Symmetrical alarm relative to the reference variable
A single hysteresis value Hy.2 (negative), an alarm threshold
AL.2 and the value to which it relates are set. The previous
alarm threshold (in this case AL.1) is used as the relative
value.
With the direct alarm setting, the alarm is triggered when
the reference value (A2.r) is less than the value AL.2 -AL.1,
or is greater than the value AL.2 + AL.1.
With the reverse alarm setting, the alarm is triggered when
the measured value is between AL2 - AL.2 and AL.2 + AL.1.
81901 "MSW_GPC-40/600A"_03-2021_ENG_page 138
Normal absolute alarm
AL.2
AL.1
alarm 1
alarm 2
Symmetrical absolute alarm
AL.1
reverse
direct
Alarm relative to the reference variable
AL.1+AL.2
AL.1
reverse
direct
Symmetrical alarm relative to variable
AL.2+AL.1
AL.1
AL.2-AL.1
reverse
direct
AL.2 - Hy.2
AL.1 + Hy.1
time
AL.1 + Hy.1
AL.1 - Hy.1
time
Hy.2
time
Hy.2
Hy.2
time
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