Yokogawa EJX930A - Manual (Page 155)

<Appendix 8. Advanced Diagnostics>
A8-11
IM 01C25T02-01E
IMPORTANT
• If the impulse line is about to be plugged at
the time when a reference value is obtained,
blockages cannot be detected accurately.
The impulse lines on both the high-pressure
and low-pressure sides need to be cleaned
before a reference value is obtained.
• All air bubbles need to be adequately purged
before a reference value is obtained.
• Reference values must be obtained under
operating condition.
• Do not obtain the reference values when the
BLOCK_MODE of SENSOR Transducer is
OOS. If carried out, an alarm of "Invalid Ref
xx" is generated.
 Start of Sampling
The sampling of reference value is carried out
for 180 seconds, which is the default value set to
DIAG_PERIOD.
1) Confirm that the sampling period
(DIAG_PERIOD) is set to 180 seconds.
2) Set “Reference” to DIAG_MODE.
The sampling starts soon after the setting.
IMPORTANT
• For the each parameter, the one value is
given. If “Reference” is set to DIAG_MODE
again, the value is updated and overwritten.
• If the power supply is shut down during the
sampling, DIAG_MODE becomes “Stop”.
Set “Reference” to DIAG_MODE in order to
carry out the sampling again.
 End of Sampling
After about 180 seconds, the sampling
automatically finishes. The “Reference” setting
of DIAG_MODE changes automatically to
“Calculation” and the termination time is recorded to
REFERENCE_TIME.
1) Confirm that the setting of DIAG_MODE
changes to “Calculation”.
2) Check the termination time recorded into
REFERENCE_TIME.
 Reference Values
Confirm the latest values are obtained into the
following parameters.
• REFERENCE_FDP
• REFERENCE_FSPL
• REFERENCE_FSPH
• REFERENCE_BLKF
• REFERENCE_DPAVG
 Invalid Ref BlkF, fSPh, fSPl, or fDP
When the enough reference fluctuation value is not
obtained, an alarm of Invalid Reference value for
each parameter is generated and also the part of
ILBD function related to the Invalid Ref BlkF, fSPh,
fSPl, or fDP is not carried out.
Confirm the alarm of Invalid Ref BlkF, fSPh, fSPl, or
fDP is not displayed in DIAG_ERR.
If an alarm of Invalid Reference value is generated,
consider the process condition or obtain the
reference fluctuation values again.
NOTE
Even if an alarm of Invalid Ref BlkF, fSPh, fSPl,
or fDP is generated, “Calculation” in DIAG_
MODE is kept.
A8.2.8 Capability Test of Blockage
Detection Operation
Before performing the ILBD operation, check the
capability of the blockage detection operation.
The simulation test is performed by closing motion
of a three-valve manifold or stop valve. When
simulated blockage occurs, confirm that an alarm is
generated.
NOTE
The fluctuation amplitude of atmospheric
pressure is nearly zero with pressure or level
measurement. In such case, simulate the
blockage detection by closing the valve where
the fluctuation existed.
 Simulation of High-pressure-side
Blockage
1) Close the high-pressure-side valve.
2) Confirm the value of PRIMARY_VALUE is
stable. If unstable, open valve a little.