Technical Specifications

ValVue Digital Communications Software Ver. 2.80
582
GE Oil & Gas
I Integral time or reset time (0.1 sec), is the time constant of integral
control. Higher values of I cause less integral action, however a value
of 0 gives no integral action. Common values are 10 to 200.
D Derivative time or rate time (msec) is the time constant of derivative
control. Common values are 10 to 100.
PAdj Valves often have significantly different response when filling verses
exhausting. The proportional gain is adjusted by adding Pad}(%) to P
when the valve is exhausting.
DeadZone When the valve position is within the setpoint +/-the dead zone, no
additional position control is performed. This value is normally 0%,
however for high friction valves (e.g. valves with graphite packing) a
higher dead zone (%) helps avoid limit cycling due to the stick/slip
action of the valve. In these cases, the dead zone chosen might be
0.5% to 1%.
Beta Beta is nonlinear gain factor, ranging from -9 to 9. When beta is 0,
the controller gain is linear Otherwise the gain is the function of error
The larger the beta, the smaller the gain for small error. Typical beta
value for a valve position controller is 7 or 8.
Position Compensation
Coefficient
The response of the valve is different when the valve is nearly closed
than when the valve is nearly open. The position compensation coef-
ficient, which is a number between 0 and 9, allows you to make
adjustments to try to equalize the valve response. The normal value
is 6.
Damping Coefficient The valve response may be made slower for some applications. A
value of zero gives no damping, and a value of nine gives maximum
damping of valve motion.
Apply Clicking Apply saves to the SVI any changes that have been made to
configuration or calibration parameters.
High Pressure Enter the air supply pressure in this edit box. This value is used only
for scaling the input pressure signal to engineering units and need
not be exact.
Low PV /High PV If the process controller option is ON, you must enter the engineering
units for the process variable that corresponds to 4.0 mA and 20.0
mA. The SVI uses these values to convert the auxiliary input signal to
engineering units.
Low Remote SP /High
Remote SP
If the process controller option is ON, you must enter the engineering
units for the setpoint that corresponds to 4.0 mA and 20.0 mA. The
SVI uses these values to convert the primary input signal to engi-
neering units.
Change Mode The SVI can be in any of several operating modes: