Yokogawa YVP110 - Manual (Page 105)

<19. Diagnostics>
19-1
IM 21B04C01-01E
19. Diagnostics
19.1 Overview
A spotlighted benefit of fieldbus is the capability
of gaining a wealth of information from the field
via field devices. Particularly for a control valve,
it is expected to become possible to determine
the status of valves which have been difficult to
identify without traveling to the field and physically
examining them, to some extent from a distant
control room through the information transmitted
from the valve positioner. The YVP110 features
diagnostics as shown below.
Table 19.1 Diagnostics of YVP110
Category Diagnostic Details Access Points
Positioner
status
diagnostics
Self-diagnostics: Detects
positioner hardware
failures, positioner
software setting errors,
and so on.
• XD_ERROR
in Transducer
block
Valve
status
diagnostics
Measures valve
parameters such as the
hysteresis and slip width.
• Transducer
block’s
respective
parameters
that contain
the values
measured
during the
auto tuning
and selfcheck
Integration: Integrates
the travel distance of the
valve stem and counts
the changes in direction
of the valve action (total
cycle count), and raises
an alarm when each
integrated value reaches
a preset threshold.
• Transducer
block’s
respective
parameters
• XD_ERROR
in Transducer
block
Signature measurement
(featured in a model with
option code /BP):
Measures the signatures
of the valve and
positioner.
• ValveNavi
(Model
YVP20S)
For self-diagnostics, see Section 12.6, “Online
Diagnostics.” For valve parameter measurement,
see Section 5.3, “Carrying out Tuning” and Section
A1.2, “Parameters of Transducer Block.” The
following describes the integration and signature
measurement functions.
19.2 Integration Functions
The transducer block in the YVP110 has the
following parameters containing an integrated
operation result quantity.
Table 19.2 YVP110’s Parameters Containing
Integrated Operation Result Quantity
Item
Parameter
(upper: integrated
value; lower:
threshold)
Description
Total
number of
times of
changes
in direction
of valve
actions
TOTAL_
CYCLE_
COUNT
CYCLE_
COUNT_LIM
Incremented by 1 at each
change in the direction of
the valve action.
The dead band can
be set in CYCLE_
DEADBAND.
Total travel
(%)
TOTAL_
TRAVEL
TRAVEL_LIM
Total travel distance
of the stem position,
regardless of the direction
of the travel, represented
as a percentage of the
valve position span (full
stroke).
The dead band can
be set in CYCLE_
DEADBAND.
Total
close time
(hours)
TOTAL_
CLOSE_TIME
CLOSE_TIME_
LIM
Integrated time periods
when the valve position is
equal to or less than the
threshold set in OPEN_
CLOSE_THRESHOLD.
Total
open time
(hours)
TOTAL_OPEN_
TIME
OPEN_TIME_
LIM
Integrated time periods
when the valve position is
larger than the threshold
set in OPEN_CLOSE_
THRESHOLD
Total near
close time
(hours)
TOTAL_NEAR_
CLOSE_TIM
NEAR_
CLOSE_TIME_
LIM
Integrated time periods
when the valve position is
between a shutoff and the
threshold set in NEAR_
CLOSE_THRESHOLD.
Useful to predict
deterioration of valve
body.
Total
number
of times
of servo
output drift
warning.
SERVO_
WARN_
COUNT
Indicates the total number
of times a drift warning
occurred regarding the
output current to the I/P
module.