GE GFK-0825F S1 Alarm Ch 01, 00000 low , S1 Alarm Ch 01, 00000 high

GFK-0825F Chapter 5 Station Configuration 5-33
5
Alarm Limits
Each input channel can have two alarm thresholds, one for a low engineering units (scaled) value
and one for a high value.
Maximum values ar e +/-32,767. The hi gh threshold sh ould be great er than the low th reshold.
Threshold li mits are based on circuit sca ling. If scalin g is changed, r eview and read ju st the Alarm
Thresholds if necessary.
Alarm Thresholds can be set anywhere over the dynamic range of the signal. Typically, they are
set at levels beyond which the input should not operate or levels beyond which alternate processing
is required. They can also be set beyond the dynamic range of the signal, ensuring that they will
never be activated. See th e examples below.
1. For EACH channel in turn, first, enter a low alarm value:
S1 Alarm Ch 01
< > entr
00000 low Number of the
channel you are
now configuring
2. Pr ess F4 (entr) key.
3. Then enter a high alarm val u e:
S1 Alarm Ch 01
< > entr
00000 high
4. Use the F1 ( < ) and F2 ( > ) keys to select channels.
5. Press F4 (entr) key to save the selection.
6. Press F2 ( > ) to go to the next screen.
A circuit is expected to report engineering unit values of -20 ft/sec (-6 m/sec) to +180 ft/sec
(+50 m/sec). The high alarm is set at 150 ft/sec (+40 m/sec) and the low alarm at -25 ft/sec (-
7.5m/sec).
If an input reached its high alarm, a new threshold could be set. This could generate a high-
high alarm or an alarm-cl ear ed threshold.
An Alarm Threshold is set at 1 50 ft/sec. Upon receiving an alar m message, the CPU changes
the Alarm Threshold to 165 ft/sec by using a Write Configuration command and sends the
appropriate Clear Circuit Fault command. No alarm message is sent upon changing the
threshold unless the speed is greater than 165 ft/sec. If the speed is only 157 ft/sec but
increasing, a second mess a ge would be sent at 165 ft/sec. Since these two diagnostic mess a ges
are the same, it would be necess a ry for the program to keep tr ack of the level of the Alarm
Thresholds and recogn i ze this as a higher alarm than tha t r ecei ved initially. At the sam e tim e,
it could move the low alarm to 140 ft/sec and use this level to detect the end of the high alarm
conditions.
Example 1:
Example 2: