Yokogawa YVP110 - Manual (Page 110)

<20. Troubleshooting>
20-2
IM 21B04C01-01E
20.4 Troubleshooting Valve Control
Problem Presumed Cause Remedy Ref. Section
A change in setpoint causes
no action of the valve.
Air piping is incorrect. Correct piping. 4.2
The instrument is in FAILSAFE
state.
Write ‘Clear non-latch’ to RELEASE_
FAILSAFE parameter.
12.6.2
Air supply is not being fed. Supply proper air pressure 4.2
The valve has failed. Apply a pneumatic pressure directly
to the valve actuator and check
whether there is valve action.
3.2.3
The I/P module or control relay
has failed, or there is breakage
in the cable between the I/P
module and control relay.
If the output pressure does
not increase even though the
SERVO_OUTPUT_SIGNAL value
is at maximum, contact the nearest
service station or representative
office.
—
The valve’s full stroke is
insufficient for the setpoint
input.
The air supply pressure is not
high enough to drive the valve
actuator.
Check the air supply pressure rating
for the valve actuator and supply air
at the correct pressure, and write 4
or 2 to AUTO_TUNE_EXEC to redo
autotning.
4.2, 5.3
The range of the setpoint is
limited by software.
Check the values of SP_HI_LIM
and SP_LO_LIM in the AO block
and FINAL_VALUE_RANGE in the
transducer block.
13.3,
Appendix 1
The deviation between
the setpoint and readback
signal remains.
The tight-shut or full-open action
is active.
Check the values of FINAL_VALUE_
CUTOFF_HI and FINAL_VALUE_
CUTOFF_LO.
12.2.4,
Appendix 1
The travel calibration has not
been performed correctly.
Write 2 to AUTO_TUNE_EXEC to
perform 0 &100% point adjustment.
5.3
The valve oscillates
cyclically (limit cycle).
The friction of grand packing is
large.
1) Write 4 or 3 to AUTO_TUNE_
EXEC to redo auto tuning.
5.3
2) Use the actuator of proper size. —
The dead band of integral action
is too little.
Write 4 or 3 to AUTO_TUNE_EXEC
to redo auto tuning. Or, increase the
SERVO_DEADBAND setting until
the valve stops oscillating.
5.3, 12.7,
Appendix 1,
Appendix 6
There’s air leak from the pipe
of output pressure, or feedback
lever is not correctly attached.
Check the piping and attachment of
the lever, and write 4 or 3 to AUTO_
TUNE_EXEC to redo autotuning.
Chapter 3,
5.3
Valve responses are too
slow.
If only the responses that require
air suction are slow, it means
that the regulator’s maximum
capacity is large enough.
Replace the regulator. —
The I/P module’s nozzle has
become blocked from dirt
contained in the air supply or the
like.
Check whether or not error 114
or 122 occurs in XD_ERROR in
steady states. If it does occur,
contact the nearest service station or
representative office.
12.6.1
The control relay’s nozzle
has become blocked from dirt
contained in the air supply or the
like.
Check whether or not error 114 or
122 occurs in XD_ERROR in steady
states.
12.6.1
The control gain is insufficient. Write 4 or 3 to AUTO_TUNE_EXEC
to redo auto tuning. Or, increase the
SERVO_GAIN setting.
5.3, 12.7,
Appendix 1,
Appendix 6
There’s air leak from the pipe
of output pressure, or feedback
lever is not correctly attached.
Check the piping and attachment of
the lever, and write 4 or 3 to AUTO_
TUNE_EXEC to redo autotuning.
Chapter 3,
5.3
The pressure balance deviation
is too large.
Adjust the pressure balance of
control relay.
6.3.4