5.3.3 Hysteresis
Set alarm-1 and alarm-2 hysteresis, in
[E09: HYSTERESIS1]
and
[E10: HYSTERESIS2]
. Hysteresis is a value added to the
alarm setpoint in order for an alarm status to be released (to
normal) after the alarm status has been activated. The alarm
status will be released in the following conditions, depending
on the direction of alarm action.
* When HIGH ALM (high-limit alarm) is set: Alarm is released
when input signal < (alarm setpoint - hysteresis).
* When LOW ALM (low-limit alarm) is set: Alarm is released
when input signal > (alarm se hysteresis).
•
Setting range: A range of 0 to 100% of input range
•
Setting resolution: 0.1%
5.3.4 Alarm ON Delay and Alarm OFF Delay
Set alarm-1 and alarm-2 ON delays in
[E11: ON DELAY1]
and
[E12: ON DELAY2]
and then alarm-1 and alarm-2 OFF delays
in
[E13: OFF DELAY1]
and
[E14: OFF DELAY2]
.
An alarm ON delay is a delay time from the establishment of
alarm condition to alarm output; an alarm OFF delay is a delay
time from the establishment of return-to-normal condition to
output.
•
Setting range: 0 to 999 seconds
•
Setting resolution: 1 second (Note that about 0.2 second
will be added to set time to prevent erroneous operation.)
For example, when an alarm ON delay is set to 1 second,
alarm output is generated if alarm status continues for
more than 1 second after the input value exceeds the
alarm setpoint. Further, when an alarm OFF delay is set
to 2 seconds, alarm output is released if normal condition
continues for more than 2 seconds after the input value has
returned to normal from the alarm status.
5.3.5 Direction of Relay Action
Set the direction of relay energizing in alarm-1 normal
condition and alarm-2 normal condition by selecting from
among NRM DE-ENERGIZED (de-energized under normal
condition) and NRM ENERGIZED (energized under normal
condition) in
[E15: RL1 ACTION]
and
[E16: RL2 ACTION]
and set them.
6. DESCRIPTION OF ALARM ACTIONS
This chapter describes examples of alarm actions under the
following conditions.
Item
Alarm 1
Alarm 2
Parameter
Setpoint Parameter
Setpoint
Direction of alarm
action
E05: ALM1 ACTION
High-limit
alarm
E06: ALM2 ACTION Low-limit
alarm
Alarm setting
E03: SET POINT1
80%
E04 : SET POINT2
15%
Hysteresis
E09: HYSTERESIS1 10%
E10 : HYSTERESIS2 5%
Alarm ON delay
E11: ON DELAY1
1 sec
E12 : ON DELAY2
3 sec
Alarm OFF delay
E13: OFF DELAY1
2 sec
E14 : OFF DELAY2
4 sec
Description of
alarm actions
The alarm is output if the
condition where the input value
is 80% or more of high-limit
alarm continues for 1 second
or more.
After the alarm is output, when
the condition where the input
value is less than 70% of
high-limit alarm continues for
2 seconds or more, the status
returns to normal.
The alarm is output if the
condition where the input value
is 15% or less of low-limit
alarm continues for 3 seconds
or more.
After the alarm is output, when
the condition where the input
value is more than 20% of
low-limit alarm continues for
4 seconds or more, the status
returns to normal.
Figure 6.1
Alarm-1 action
Alarm-2 action
Normal
Normal
Normal
Normal
Alarm
Alarm
[
％
]
0
20
15
40
60
80
100
1 s.
2 s.
3 s.
4 s.
Alarm-2 hysteresis (5%)
Alarm-1 hysteresis (10%)
Alarm-1 setpoint (80%)
Alarm-2 setpoint (15%)
Elapsed time s.
[1]
[2]
[3]
[4]
Alarm-1
ON delay
Alarm-2
ON delay
Alarm-2
OFF delay
Alarm-1
OFF delay
Alarm conditions established
Alarm conditions
established
Normal conditions
established
Normal conditions established
High-limit alarm ON
Low-limit alarm ON
High-limit alarm OFF
Low-limit alarm OFF
[1] Alarm status does not continue for more than 1 second after the
alarm conditions are established at alarm 1.
[2] Normal status does not continue for more than 2 seconds after
the normal conditions are established at alarm 1.
[3] Alarm status does not continue for more than 3 seconds after the
alarm conditions are established at alarm 2.
[4] Normal status does not continue for more than 4 seconds after
the normal conditions are established at alarm 2.
4
IM 77J01H07-01E
5th Edition
