Nexen RSTC1100 964528 - Manual (Page 18)

18 FORM NO. L-21204-C-0705
3. Start the machine and run at a moderate web speed
and tension.
Note if the output oscillates excessively or if the
amount of time taken to reach the tension setpoint
after web speed becomes consistent is too long. It
is normal for the output value to fl uctuate as long
as the web tension does not.
• If the output oscillations are not excessive and
the amount of time is too long, stop the machine.
Increase Gain by 0.5 and return to step 3.
• If the output signal begins to oscillate excessively,
stop the machine. Decrease Gain by 0.5 and return
to step 3.
• If performance is satisfactory, proceed to step 4.
4. Load a small roll on to the roll stand.
5. Start the machine and note if there are excessive
output oscillations.
• If the output oscillations are excessive, stop the
machine. Reduce the Gain by 0.5 and return to
step 5.
6. Continue to test for output oscillations until the roll is
as small as practical.
During tuning, if the Gain value reaches 1.0 and further
adjustment is required, then stop the machine, decrease
Stabilization by 1.0, set Gain to 2.5 and return to the
tuning process.
Likewise during tuning, if the Gain values reaches 10.0
and further adjustment is required, then stop the machine,
increase Stabilization by 1.0, set Gain to 2.5, and return
to the tuning process.
TUNING PROCEDURE
Most applications will only require adjustment of
Gain and Stabilization to tune the RSTC. Advanced
tuning parameters are available for more demanding
applications.
Note: To view diagnostics while tuning, select the
DIAGNOSTICS icon from the toolbar; then select
START in the Communication Pane (See Diagnostics
Section).
The RSTC features an adaptive algorithm that is user
tuned. After tuning, the algorithm will automatically adapt
internal gain values to account for changes in roll diameter
and inertia. This algorithm is modeled after unwinding
and winding applications which results in an non-linear
adaptation process that closely follows the actual changes
occurring in a web machine.
Stabilization is an important variable that must be set
properly for the RSTC to perform correctly. If it is set too
low, Gain will not be able to be set high enough for proper
operation and could also cause a high frequency tension
oscillation. If it is set too high, the RSTC could produce a
low frequency tension oscillation.
When tuning it is important to check for output oscillations
during large and small roll machine start conditions.
Further, initial tuning performed for a small roll may not
result in adequate performance with a full roll as the RSTC
could be sluggish. Therefore, start with Gain and Stability
set at their default values and begin tuning with as large a
roll as practical. For winding applications, us the default
Stabilization and Gain value and only change the Gain
as necessary in order to build a large roll then follow the
tuning procedure.
1. Set Stabilization to 15.0 and Gain to 2.5
2. Load as large a roll as practical on to the roll stand.
Figure 21 Tuning Screen
TUNING
TUNING WINDOW
Select the TUNING icon from the toolbar. (See Figure
21).
Note: After changing values, the SEND key must be
pressed to send the values to the RSTC.
Gain: Adjusts response of RSTC to magnitude changes in
tension. Higher values cause a more aggressive response
and lower values cause a lesser response.
Stabilization: Tunes the tension control algorithm to the
natural frequency of the empty core shaft that is being
controlled. When set properly this parameter allows the
gain to be set for best performance.