25
5.2.2.2 Readings Section
The
Readings
section displays the current
operational readings of the flowbench as illustrated
in Figure 5.7.
5.2.2.3 PID Settings Section
PID Tuning parameters should not be modified
unless instructed to do so under the direction of
SuperFlow Service Technician and then done so
by the administrator only.
NOTICE
The
PID Settings
section displays the current
P
roportional
I
ntegral
D
erivative (PID) controller tuning
values for the flowbenches
Flow
and
Pressure
. You
must be logged in as an administrator (SETUP login) in
order to unlock and adjust the parameters illustrated in
Figure 5.8.
1
Allow Flow PID Adjust:
Allows an administrator to
select if the PID values for
flow
are on
LOCK
(selected
in Figure 5.8) or
UNLOCK
. If
UNLOCK
is selected the
PID values can be changed.
2
Allow Pressure PID Adjust:
Allows an administrator
to select if the PID values for
pressure
are on
LOCK
(selected in Figure 5.8) or
UNLOCK
. If
UNLOCK
is
selected the PID values can be changed.
3
Flow/Pressure PID P:
The
Proportional (P)
, or
gain, positions the orifice at a percentage proportional
to the error.
4
Flow/Pressure PID I:
The
Integral (I)
is the rate
at which the flowbench will reach that set point.
5
Flow/Pressure PID D:
Derivative (D)
controls the
rate of change.
Determining the appropriate settings for P and I can
be a difficult task. A simple method for tuning is to
first set the I and D values to zero. Then, increase the P until the system begins to oscillate and divide by 2.
Then increase I until oscillation starts and divide by 2. A fast PID loop tuning usually overshoots slightly to
reach the set point more quickly; however, some systems cannot accept overshoot. If this is the case, the
tuning will need to be slower.
Figure 5.7: Readings
Figure 5.8: PID Settings
1
2
3
4
5
5.0 Operation
