Cleveland Motion Controls WebPro Unwind Brake Tension Controller MWP – 12662 - 0 REV BA - Manual (Page 19)

AO-70173
19
Revision BA
WebPro Unwind Brake Tension Controller
Access the Adjust PI stability menu from the Commissioning menu. Run the machine with the Controller
in Auto at a Tension Set Point of approximately 50%. Use the SCROLL keys to select the parameter to be
changed and adjust the parameter using the numeric keys or the +/- keys. Press the CONFIRM key to
implement and save the change. An asterisk alongside the Product Number indicates that a parameter
has been changed and that the CONFIRM key must be pressed to implement and save the change.
When the best performance is achieved stop the machine, remember to press CONFIRM and then press
SET UP to return to the Commissioning menu.
To simplify the tuning there are five factory set PI values. One of these values should be suitable for most
applications. If it is found necessary to apply different PI values, select Custom and starting from PI
values that gave stable but sluggish operation, reduce the P band % value and reduce the I time value
until the desired performance is achieved. Remember to press the CONFIRM key before exiting the
Product Parameter or the Adjust PI stability menus in order to implement and save any changes.
The five preset PI values are:
very slow slow medium fast very fast
Proportional band 2000% 1200% 800% 500% 200%
Integral time 20 sec 12 sec 8 sec 5 sec 2 sec
Inertia Compensation
This feature is only available in Unwind Brake mode if a line speed tacho or encoder is available and is
used to reduce the tension error caused by the reel inertia when the machine accelerates or decelerates.
While accelerating or decelerating the machine at the normal maximum rate observe the measured
tension bar graph and the desired tension set point triangle. If these differ by more than 10% adjust the
Inertia Time Constant and the Coefficient to compensate for any increase in tension while accelerating or
decrease in tension while decelerating. The Inertia Time Constant determines the rate of correction; the
Coefficient determines the amount of correction.
"Soft Start”
The Unwind Brake "Soft Start" feature will prevent web snatch on start up from rest if the web is slack.
The "Soft Start" feature is enabled by the Machine Start input, Select Auto input or by the Auto key but the
Controller is only activated when the measured tension exceeds 5% of maximum tension. This 5%
tension is generated when the machine starts by the reel inertia and the Output Level Bias. The 5% level
is part of the program and is not adjustable.