ABB COMMANDER C355 - Page 78

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…5 CONFIGURATION MODE
5.4 Level 8 – Alarms
Note. Any type of alarm can be used to sound an annunciator (klaxon/horn) which is disabled when the
alarm is acknowledged. This is achieved by assigning the relay to the acknowledge state of the alarm instead
of the actual alarm state.
rLY.x
ACK.x
RLY.x
Horn
Relay assigment
frame in Level C,
Output Assignment.
Trip point
Operator
acknowledges
alarm
Alarm State
(
A.x )
Acknowledge State
(
ACK.x )
Process
Variable
On
Off
On
Off
Alarm On
Alarm Off
Negative
Trip Value
Positive Trip Value
Low Deviation Alarm
Control Set Point
Hysteresis
Low Deviation
+ve Trip Value
Alarm On
Alarm Off
Hysteresis
Low Deviation
–ve Trip Value
Process
Variable
High Deviation
+ve Trip Value
Hysteresis
Alarm On
Alarm Off
Control Set Point
Alarm On
Alarm Off
Positive
Trip Value
Negative
Trip Value
High Deviation
–ve Trip Value
High Deviation Alarm
Hysteresis
Process Variable
Fig 5.3 Using an Alarm to Sound a Horn
Fig 5.4 High and Low Deviation Alarm Action