Alarms; Delayed High/Low Process Alarm - ABB C1900 Operating Instructions Manual

4 ALARMS

Note. Refer to Programming Guide (IM/C1900–PGR or IM/C1900–PGC) Section 3.4 for alarm configuration procedures.
4.1 Delayed High/Low Process Alarm – Fig. 4.1
The operation of a Delayed High/Low Process Alarm is identical to that of the Standard High/Low Process Alarm but the alarm
can be enabled/disabled by use of a digital signal.
The alarm state is held off whilst the enable signal is off and continues to be held off for a pre-configured period of time after the
enable signal is switched ON (irrespective of the process variable value). Once the pre-configured alarm delay time has expired,
the alarm operates in the same manner as a standard high/low process alarm.
Process
Variable
1
Process variable goes above trip point but alarm is not activated because enable signal is low
1
(Alarm Disable)
2
Alarm Enable signal is switched ON by activation of milking system. Alarm delay timer started.
Process variable goes above trip point but alarm is not activated because alarm delay time has
3
not expired.
Alarm delay timer expires, alarm is now enabled. Alarm is activated because process variable
4
is above trip point
5
Process variable goes below trip (hysteresis) point therefore alarm is de-activated.
Process variable goes above trip point, alarm is activated (alarm is enabled and delay time has
6
expired)
.
Alarm Enable signal is switched OFF by activation of refrigeration system. Alarm is disabled
7
immediately. Alarm de-activates.
Delay Time
2 3
.
.
Fig. 4.1 Delayed High/Low Process Alarm
4 5
Trip Point
Hysteresis
Alarm Enabled
Alarm Disabled
Alarm On
Alarm Off
6 7
7