VVP10 HART
HART
®
VALVE POSITIONER
INSTALLATION, OPERATION, CONFIGURATION AND MAINTENANCE MANUAL
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31
PID CONTROL
This directory (
Specific/PID Control
) allows user to freely configure the parameters of the PID control, for fine control
tuning.
Proportional Factor Kp (
PID Kp
)
It sets the proportional parameter of the control, also called gain, responsible for control speed, in relation to the error
(SP% - PV%).
A very low Kp value will result in a slow control, while a very high Kp value will result in oscillation of the system around
Setpoint.
Integral Factor Tr (
PID Tr
)
It sets the integral parameter of the control, responsible for the search of the Setpoint in a smooth and gradual way,
ensuring an accurate approximation of the desired position.
This factor is used only when the error is relatively low, resulting from proportional and derivative actions, and its action
is inversely proportional to its value.
A very low value of Tr will result in a quick integration of error search, which can cause oscillation. A very high value
of Tr will result in very slow and inefficient integration.
Derivative Factor Td (
PID Td
)
It sets the derivative parameter of the control, responsible for controlling the oscillation around the Setpoint, resulting
from the proportional action.
A very low value of Td will result in ineffectiveness of the derivative action, allowing the system to oscillate. A very high
value of Td will result in an initial brake on the integral action, but later oscillation around the Setpoint.
PID Deadband
It sets the maximum allowed error before the PID control is activated. The default value for this parameter is zero,
leaving the control always active.
HINT
Auto Tuning calculates parameters that will sufficiently meet the control in most situations. If you need to
change the parameters manually, try to change the Td parameter proportionally to the KP parameter
change.
WARNING
If the user changes the PID control parameters incorrectly and does not record the previously calculated
values, simply perform the Auto Tuning procedure.
