ABB C1900 Series, Operating Instructions Manual

7

Hysteresis

Alarm On

Alarm Disabled

Alarm Enabled

Trip Point

Alarm Off

Delay Time

Process
Variable

1

2

3

4

5

6

7

Process variable goes above trip point but alarm is not activated because enable signal is low
(Alarm Disable)

.

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
not expired.

Alarm delay timer expires, alarm is now enabled. Alarm is activated because  process variable
is above trip point

.

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
expired)

.

Alarm Enable signal is switched OFF by activation of refrigeration system. Alarm is disabled
immediately. Alarm de-activates.

1

2

3

4

5

6

7

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.

Fig. 4.1 Delayed High/Low Process Alarm

4 ALARMS