Flowserve DFP17 - Manual (Page 16)

16 DataFlo Digital Electronic Positioner DFP17 Installation, Operation and Maintenance Instructions WCAIM2037
The actuator will run to the setpoint at full speed and
then brake if the time to close time setting is less than
that measured in the calibration routine.
4.3.10 Setpoint Curve Function
The display will alternately display SFc and either Lin or
FrE1, FrE2, FrE3, or FrE4.
This function tells the positioner the desired shaft
positioning characteristic with respect to input signal.
Lin causes the shaft position to vary in a linear fashion
as the input signal changes (i.e., if the signal is at 50
percent, the shaft position will be at 50 percent of the
selected operating range).
The FrE1-FrE4 curves allow 21 setpoint vertices to be
set. In this way, a custom shaft positioning characteristic
can be entered. There is a vertices set (data point) at
4 mA and then every 0.8 mA up to and including 20 mA.
The vertices are displayed as SL 0 to SL 20 and will only
be displayed when one of the FrE1-FrE4 curves is chosen
as the setting. The SL parameters can be found in the
menu between the PrSt parameter and the CodE
parameter. Use the UP and DOWN switches to select and
change the vertices settings.
The factory installed default curve for the FrE1 setting is
the 1:25 equal percentage curve and for the FrE2 setting
it is the 1:50 equal percentage curve. The factory default
settings for the FrE3 and FrE4 curves are linear.
NOTE: Definition of equal percentage: for equal
increments of valve rotation, the Cv increases by a given
percentage over what it was at the previous setpoint.
4.3.11 Positioner Deadband
The display will alternately display dEbA and the
deadband value.
The deadband is used to prevent oscillations about a
setpoint because of small fluctuations in either the
setpoint signal or the position feedback signal. The
deadband represents a plus and minus percentage of the
full range of either the input signal or the feedback signal.
Fixed deadband values can be selected from 0.1 to 10.0
(percent) of range. When the DOWN switch is pressed
when the right most digit is selected, the display will
show Auto. Pressing SEL while on that screen will select
Auto deadband.
A deadband setting of Auto will allow constant automatic
adjustment of the deadband in an adaptive fashion as
required for best performance. This is the recommended
setting. The lower Auto default value is .5 but this can be
changed with the manual setting. Whatever value has
been set for the manual deadband setting, becomes the
lower limit for the Auto deadband mode.
4.3.12 Loss of Signal Position and Delay Time
The display will alternately display SPOS and the position
the valve will move to if there is a loss of signal. A loss of
signal condition occurs in either of two situations: 1)
When the positioner is in analog position control and the
input signal is less than 2 mA; or 2) When the positioner
is controlled by the serial data link (digital control) and
no signal has been received within the SPt time period.
When a loss of signal occurs in the analog control mode,
the positioner will immediately go to the SPOS position.
A HOld option specifies the positioner is to hold its
current position. The positioner will hold the SPOS
position until a valid analog input signal is present for the
SPt delay period. If the SPt parameter is set to zero
seconds, restoration of the signal will cause the
positioner to work as normal with no time delay.
A loss of signal in the digital control mode means the
positioner has not received a valid command within the
SPt time period. In that case, the positioner will
immediately go to the SPOS position. A HOld option
specifies the positioner is to hold its current position. The
positioner will hold the SPOS position until a valid digital
position command is received.
The display will alternately display SPt and the delay time
(in seconds). The time range is 0 to 9999 seconds. A
time of 0 in analog control mode disables the loss of
signal option. A time of 0 in digital control mode
effectively disables the loss of signal option by allowing
an infinite time between received commands. In digital
control mode, non-zero SPt time values less than three
seconds will use three seconds as the delay.
4.3.13 Power-On Position and Delay Time
When power is first applied to the positioner and the unit
is in analog signal control mode, it will go to the position
specified by the PPOS parameter for a time specified by
the PPt parameter. During that time, any input signal is
ignored.
If the unit is in PC Cmd control mode and there is a valid
PC signal, the unit will respond to the signal immediately,
otherwise, it will go to the power on position for the PPt
time and then go to the SPOS position for the SPt time.
The display will alternately display PPOS and the position
(in percent) the valve will move to when power is first
applied or when power is restored. The actuator will hold
that position for the time specified in the next step. The
position range is 0.0 to 100.0% and HOLd. A HOLd
option specifies the positioner is to hold the last position
(i.e., the actuator will not move).
The display will alternately display PPt and the time (in
seconds) that the PPOS position will be held. During that
time, the positioner will ignore any input signal and will
hold the PPOS position. The time range is 0 to 9999
seconds. A time of 0 disables this option such that the
positioner will immediately respond to the input signal
when power is first applied or restored.
Flow Control
Worcester Actuation Systems