10 tuning, 10 tuning -17 – Yokogawa EJA440E User Manual

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<4. Diagnostics>

4-17

IM 01C25T01-06EN

4.2.2.10 Tuning

When the pressure fluctuation amplitude in fluids is

not sufficiently large or an alarm is often generated

according to the process condition, tune up by

changing the threshold for the blockage detection

(Limit parameters) or the sampling period (

Diag

Period) to enhance the accuracy of the blockage

detection The ILBD operation must be stopped to

tune up. Set “Stop” to

Diag Mode.

Threshold Value

The figure below shows the image of tuning effect

with a monochrome bar.
(a) The tuning image of the threshold values for

(1)

Ratio fDP: Sqrt (fDP/Ref fDP),

(2)

Ratio fSPl: Sqrt (fSPl/Ref fSPl),

(3)

Ratio fSPh: Sqrt (fSPh/Ref fSPh)

F0411-1.ai

0

1

3

Threshold (lower side)

Threshold (upper side)

(1)

Lim fDPmin

(2)

Lim fSPlmin

(3)

Lim fSPhmin

(1)

Lim fDPmax

(2)

Lim fSPlmax

(3)

Lim fSPhmax

(b) The tuning image of the threshold values for

(4) Sqrt (

BlkF/Ref BlkF)

F0411-2.ai

0

-1

1

Threshold (lower side)

Threshold (upper side)

(4)

Lim BlkFmin

(4)

Lim BlkFmax

Figure 4.8

Tuning Image of Threshold Value

Move the threshold toward the white.

• It becomes increasingly likely to give a false

alarm due to the disturbance from environment

change.

• If flow/differential pressure is below

Lim

DPAvgmin or exceeds Lim DPAvgmax,

pressure fluctuation is likely too small or too

large to detect the blockage.

Move the threshold toward the black.

• It enables to be insusceptible to disturbance

such as environment change and to detect the

blockage easier.

• It becomes giving an alarm of the blockage after

the blockage has been progressed.

(1) Setting by DD and DTM (excluding EJX

HART 5 DTM based on FDT1.2)

• Procedure to call up the

threshold related

display

DD and DTM

(excluding

EJX_HART

5[1.2])

[Root Menu] → Diag/Service → Diag

Parameters → ILBD parameters →

Configuration → Diag Lim →

The default values at the factory setting are the

values of

Lim fDPmax to Lim BlkFmin shown in

Table 4.3.
Change the threshold value to solve your problem

according to the above image.

1) Set “Stop” to

Set Diag Mode.

2) Change the unsuitable value of

Diag Lim

parameters corresponding to the each

blockage detection.

Note: Set to “Calculation” after setting the parameter.

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

(2) Setting by EJX HART 5 DTM based on

FDT1.2

Combination of threshold depend on the sensitivity

of blockage detection can be selected from High,

Medium, or Low in the

Sensitivity parameter.

• Procedure to call up the display

EJX HART 5

DTM based on

FDT1.2

Diag and Service → Advanced

Diag Configuration → Impulse Line

Blockage Detection → Threshold →

sensitivity

When select “Custom” in the Sensitivity parameter,

you can set each threshold individually.

Set the

Diag Mode to “Stop” before changing the

threshold.

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