GE FVP110 - Checking Hunting Operation; Improving the Response Time; Moderate Response with a Flat Overshoot; Modifying Overshoot

FVP 110 Fieldbus Valve Positioner Manual
256
GE Energy
Modifying overshoot
❑ Increment the value for SERVO_GAIN. Verify the 10% step response and
increment the value by 1.5 times.
❑ If you input a value in a small step of approx. 5% or less, and you cannot obtain a
significant improvement effect compared to the 10% step, increment the value for
SERVO_RATE by 0.2 to reduce an excessively rapid response.
❑ The same boost value is set on both the air delivery and exhaust sides using Auto
Tuning. If the overshoot on the exhaust side is larger than that on the air delivery
side for a double-acting model, input a negative value in X_BOOST_VALUE [1] [2],
without changing the value of 0 in X_BST_ON_THRESHOLD [1] [2] and
X_BST_OFF_THRESHOLD [1] [2]. First, try to input a negative value of half that of
BOOST_VALUE [1][2], and if necessary, increment or decrement the value by 1.
Improving the Response Time
❑ If you input a value in a small step of 5% or less and the response is slow,
increment or decrement the value for BOOST_VALUE [1] [2] and
X_BOOST_VALUE [1][2] by 1, respectively.
❑ If necessary, increment the value for SERVO_GAIN by 30.
Checking Hunting Operation
Input a value in a large step of approx. 80% to ensure the hunting operation does not
occur. If the hunting operation does occur, decrease the value for SERVO_GAIN to 2/3 or
1/2 of the originally entered value.
Moderate Response with a Flat Overshoot
Figure 88 Moderate Response with a Flat overshoot
Occurrence of a Limit Cycle
If you increase the value for SERVO_RESET, response slows down and a limit cycle can
be prevented by:
❑ . Verifying a large step response of 30% or more and incrementing the value by 5.