Yokogawa EJX440A - Manual (Page 48)

<4. Diagnostics>
4-8
IM 01C25T01-01E
4.2.2.4 Operating Procedure
The basic flow of the ILBD operation is as follows.
1) Initial setting
2) Condition check
3) Start up
4) Perform the ILBD algorithm.
If an alarm is often generated or the process
condition changed in the ILBD operation, do
tuning to change the alarm setting, or to reset the
reference values.
Fill out the information to the checklist, at the
process shown in below figure.
F0409.ai
NG
1, 2
7
3
4
5, 6
10
1-1) Alert Setting
• Enable an alert to be generated by
Diag Out Option parameter.
1-2) Alarm Masking
• Select the alarm status to display on
LCD or to give an alert by Diag
Option parameter.
2-1) Check Stability of PV
• Check the stability of Primary value.
2-2) Check Fluctuation Values
• Check whether the fluctuation values
are available for ILBD.
3-1) Obtain Reference Values
• Obtain a reference fluctuation value of
differential pressure/pressure and
static pressure under normal condition.
3-2)
Check Detection
Capability
• Simulate the blockage detection
operation with a three-valve
manifold or stop valve.
Tuning
• Change the threshold value by
Limit parameter.
• Change the sampling time by
Diag Period parameter.
Reset Reference Values
• Reset a reference fluctuation
value of differential
pressure/pressure according to
process condition.
4) Perform ILBD algorithm
Refer to 4.2.2.11
Refer to 4.2.2.10
Process condition is
changed by a
comparison of the
condition when the
reference values were
obtained.
Blockage Detection
Alarm is generated.
Refer to 4.2.2.9
Spurious alarm detection.
Refer to 4.2.2.8
Refer to 4.2.2.7
Refer to 4.2.2.6
Refer to 4.2.2.6
Refer to 4.2.2.5
Refer to 4.2.2.5
1) Initial Setting
2) Condition
Check
3) Start up
Items on
Check sheet
OK
Figure 4.2.4 Flow Chart of ILBD Operation