Cleveland Motion Controls WebPro Motor Powered Unwind Tension Controller MWP – 12662 - 1 REV BA - Manual (Page 5)

AO-70172
4
Revision BA
WebPro Motor Powered Unwind 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.
Motor Powered Unwind System
Motor powered unwind systems can
operate at tension levels lower than those
of a brake system and can generate
tension when the machine is at rest (stall
tension) provided the machine is designed
to allow this. The motor and drive must be
suitable for continuous regenerative
operation. The Controller requires either
tachogenerators ( tachos ) or encoders or a
combination of both, for the unwind reel
speed and for the line speed. These speed
signals are used by the Controller to
calculate the reel diameter. The motor
powered unwind Controller provides
constant tension; there is no taper tension
feature.
All drive electronics MUST be isolated from any supply voltage and the electronics common must be
connected to ground/earth. If the drive electronics are not isolated or the common cannot be connected to
earth, consult CMC Inc before use.
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