Cleveland Motion Controls WebPro Intermediate Tension Controller MWP-12663 REV BA - Manual (Page 4)

AO-70174
4
Revision BA
WebPro Intermediate Tension Controller
General Description
The WebPro Digital Tension Controller is part of a closed loop tension control system with transducer
feedback. The Controller continuously controls the web tension to the TENSION SET POINT value and
displays the true web tension on an LCD screen, either as a percentage or in engineering units. The
screen will display the tension applied to each transducer separately by pressing the < LEFT tension or >
RIGHT tension key. The sum of the LEFT and RIGHT tensions is displayed when the < > TOTAL key is
pressed. The Controller will control to the TOTAL tension value even when the LEFT or RIGHT tension is
being displayed. The Controller also has a dual range tension indication feature.
The measurement of actual web tension is made by sensing, with strain gauge transducers (sometimes
referred to as "load cells"), the force on a sensing roller caused by the tension in the web. The electrical
signal from the transducers is a combination of tension force and sensing roller weight. The weight of the
sensing roller is zeroed out electrically, leaving the tension force only to be displayed on the screen.
For wide web applications two transducers are recommended, one on each end of the sensing roller; for
narrow web, wire, cable and filaments one transducer can usually be used.
Intermediate Drive System
With the Controller in automatic mode the
measured tension is compared with the
desired tension. Any tension error is multiplied
by the incoming line speed making the
correction speed proportional. This multiplied
tension error is then conditioned by the PI
then added to the line speed signal and used
as a speed demand to the controlled ( slave )
drive. This is described in the Machine
Parameter menu as; Output Trim only - NO.
Alternatively the trim signal only may be
output as +/- 2V or as +/- 10V maximum. This
is described in the Machine Parameter menu
as; Output Trim only - YES. When this mode
is used the controlled drive will usually require
a line speed input in addition to the trim input.
The transducers and the controlled drive may be before the master drive or after, this is selected in the
Machine Parameter menu. Both the master drive and the controlled drive should be four quadrant
regenerative types to prevent overhauling.
All drive electronics MUST be isolated from any supply voltage and the electronics common (0V) should
be earthed. If the drive electronics are not isolated consult CMC Inc BEFORE use.
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