Yokogawa YVP20S - Manual (Page 131)

14-5
IM 21B04C50-01E
<Toc> <Ind> <14. DIAGNOSTIC SERVICES>
14.3 Signature
Signature function is one of the functions in diagnostic function. The aim of this function is
to detect the degradation failure and to grasp the condition of the control valve or the
positioner by comparing the history of signature characterization. To accomplish the aim,
the positioner must have the function to measure and retain the measured data of the
characteristics of the control valve and the positioner itself.
Measuring procedures of signature of the control valve and the positioner will force the
control valve to move the stem position; thus the measuring procedures must be performed
while the process is in off line condition and the device is in Out of Service state.
YVP with /BP option for single acting actuator type has the ability to store locally the stan-
dard actuator signature data. In case the user is connected to a YVP in the Diagnostics
window, the above valve signatures can be retrieved from YVP’s non-volatile memory and
compared to the current valve position, output pressure and other process information with
valve signatures to determine if there is a shift in system performance.
Figure 14.5 Signature Tab
The YVP with /BP option for single acting actuator type supports 5 types of user signature
functions:
• Double acting actuator type and single acting actuator type without / BP option sup-
port only Step response Test and Positioner Signature.
• Actuator Signature: Static characteristic of the control valve.
• Extended Actuator Signature: Extended Static characteristic of the control valve.
• High Resolution Actuator Signature: High resolution Static characteristic of the control
valve.
• Step Response Test: Step response characteristic of the control valve system.
• Positioner Signature: Static characteristic of the control valve system.