Yokogawa EJA440E - Manual (Page 53)

<4. Diagnostics>
4-6
IM 01C25T01-06EN
4.2.2.1 Blockage Detection
 Limit parameter
When the parameter based on pressure fluctuation
exceeds the preset value, EJX diagnoses an
impulse line as blockage and gives an alarm. The
threshold values are set to Limit parameter shown
in below table.
• Procedure to call up the display
DD and DTM
(excluding EJX_
HART 5[1.2])
[Root Menu] → Diag/Service
→ Diag Parameters → ILBD
Parameters → Configuration →
Diag Lim →
EJX_HART 5[1.2]
DTM
Diag and Service → Advanced Diag
Configurations → Impulse Line
Blockage Detection → Threshold
→ Sensitivity →
Table 4.2 Limit Parameter
# Parameter Threshold value
[1] Lim fDPmax Threshold to detect “A
Blocking” by using Ratio fDP
[2] Lim fDPmin Threshold to detect “B
Blocking” by using Ratio fDP
[3] Lim fSPlmax Threshold to detect “Large
Fluct L” by using Ratio fSPl
[4] Lim fSPlmin Threshold to detect “L Side
Blocking” by using Ratio fSPl
[5] Lim fSPhmax Threshold to detect “Large
Fluct H” by using Ratio fSPh
[6] Lim fSPhmin Threshold to detect “H Side
Blocking” by using Ratio fSPh
[7] Lim BlkFmax Threshold to detect “H Side
Blocking” by using BlkF
[8] Lim BlkFmin Threshold to detect “L Side
Blocking” by using BlkF
[9] Lim DPAvgmax Threshold to detect “ILDB over
range” by using DPAvg and to
detect “Invalid Ref xx” by using
Ref DPAvg
[10] Lim DPAvgmin Threshold to detect “ILDB over
range” by using DPAvg and to
detect “Invalid Ref xx” by using
Ref DPAvg
Table 4.3 shows the default values at the factory
setting.
NOTE
• When ILBD is performed for the first time,
use the default value. If the pressure
fluctuation amplitude is low or a false alarm
is often generated after ILBD is performed,
change the values of Limit parameters
according to the procedure described in
subsection 4.2.2.10. Tuning