Yokogawa YVP20S - Manual (Page 133)

14-7
IM 21B04C50-01E
<Toc> <Ind> <14. DIAGNOSTIC SERVICES>
• Measurement Setting Parameters
There are three measurement setting parameters: Recommended Scan Time, Scan Time
and Deviation margin.
Figure 14.7 Standard Signature Setting
Recommended Scan Time (sec): The value is read only and does not affect the
measurement. The value is calculated from the tuning parameters. It is used as a
guide for setting Scan Time (in second).
Scan Time (sec): It determines the time for round trip of the measurement. User can
set any value within the valid range. User can refer the Recommended Scan Time.
The valid range is 20 to 3600 sec.
Deviation margin (%): The measurement is performed in Proportional control algo-
rithm. In this reason, deviation between the set point value and the position value may
occur due to the non-linear characteristic existing in the control system. (Mainly valve
hysteresis) Basically, this value dose not need to be changed from the default value.
However, in case if stem position did not reach the desirable point, then increase this
value; or if stem position far exceeds the desirable point, then decrease this value to
make the measurement correctly. The valid range is 0 to 500%.
• Offset measurement
Before measuring the actuator signature, YVP will perform Offset measurement (The same
procedure in Auto Tuning) in order to prepare for the measurement.