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Electronic for proportional DC valves
Series PWDXXA-40X
Operation Manual
PWDXXA-40X_20 5715-677 UK.indd 26.01.17
Parker Hannifin Corporation
Hydraulics Group
Parker Hannifin Corporation
Hydraulics Group
How can the functionality of the control loop
be achieved?
At first you should set off the control loop (set pa-
rameter E2 to value 0 = open loop and transmit to
the electronic) and cause the pressure via manual
control to the middle of the system pressure. Next
adjust the control coefficients as described in chap-
ter “Simple tuning of a pressure control loop” (P16
at 10%) as well as the parameter E2 at 2 = external
closed loop and transmit to the electronic. If this
results in a jump of the pressure into its minimum
or maximum final value, the polarities are incor-
rect. Access the parameter P12 = feedback signal
polarity, change the value and transmit the data. By
now the pressure should be adjustable and must
remain on its value when you switch on the closed
loop control via parameter E2. The next task will
be to preset the pressue command and monitor
the pressure behavior. If the pressure even tough
is running in closed loop mode, the behavior of the
pressure rise and fall is not as required, it is neces-
sary to change the polarities of both command and
feedback signal via the parameters P11 and P12.
The control loop should now be running as desired,
you can continue with tuning of the loop.
Tuning of the closed loop control
1. Create a suitable tuning test profile – otherwise
it may be difficult for you to tell how good the
system response is (the test profile may also be
generated by an up-stream electronic module
PZD00A-40X). The test profile should start caus-
ing the system from the circulation pressure with
the desired maximum acceleration and velocity
to the required final pressure. At the final pres-
sure the system should remain for a while, that
will give you enough time to watch the pressure
value to see if it oscillates or remains stationary.
This should be followed by returning of the pres-
sue to the start value, where the stationary value
may also be evaluated.
2. Check once more to be sure that P17 and P18
are set to zero.
3. Adjust P16 to a low value, i.e. 10 %, and run the
system using the test profile. Observe the result
of the test. There are three possible outcomes:
• The pressure oscillates continuously
Stop the system quickly. Reduce the P16-value
to ½ of the initial guess, and try again.
• The pressure overshoots, but stops after one
or two oscillations
Reduce the P16-value to ¾ of the initial guess,
and try again.
• The pressure reaches the commanded value
with no overshoot
The system is usable with the estimated value
of P-gain. You should experiment with stepwise
increasing of the P16-value to see how high a
value the system will tolerate. Accuracy and
response are improved by high values, but do
not allow permanent oscillation!
4. You have now completed the basic tuning for
your control loop. The next step is to test the
performance of the system to see if it meets
your requirements. If not, the electronics has
additional control features that may be used to
improve performance, as explained below.
Содержание PWD Series
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