GE Valve Software Tools MN-Valvue-FF-IOM Manuel de service télécharger pdf (Page 126)

ValVueFF Software Interface to FVP

110

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I (seconds) Integral time or reset time, is the time constant of integral control.

Higher values of I cause less integral control action and increase

loop stability. However, higher values of I increase the time to

eliminate a steady- state position error. 0 turns off integral action

and results in a steady-state position error. Sustained deviation

can result in failsafe action if T2 is set. Therefore, 0 must be

avoided for use in most applications. The default value of 15 sec-

onds is normally changed by Auto Tune.

D (seconds) Derivative time or rate time is the time constant of derivative con-

trol. Larger derivative time causes more derivative control action.

0 disables derivative action.

Derivative Gain

(dimensionless)

Derivative gain controls the maximum response to rapid position

change. The default value of 5 is normally adequate.

Dead Zone (%) When the valve position is within its Set Point +/- 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 can be set at 0.1% to 5%

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GE Valve Software Tools MN-Valvue-FF-IOM Manuel de service Page 126