Technical Specifications

156 | =GE Oil & Gas

ESDVue launches the Advanced Tuning Parameters dialog (Figure 136).

Figure 136 Advanced Parameters Dialog

2. Adjust the parameters, referring to Table 6 for parameter descriptions, then click OK.

Table 6 Advanced Tuning Parameters

Tuning Parameter Description

Dead Zone When the valve position is within the setpoint +/- the dead zone, no addi-

tional 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 coefficient,

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.

Boost The boost field in the PID adjustments controls a supplemental pressure

or boost to speed up initial valve response from setpoint from 0 to 100%

Stroke Time Amount of time in seconds that the valve is stroked.