Set Wrap Gain - ABB PFEA 113 User Manual

3.12.6 Set Wrap Gain

3BSE029382R0101 Rev C
To be able to present actual web tension on the display, the ratio between web tension and
measured force on the load cell must be determined.
This ratio is a scaling factor called Wrap Gain.
The Wrap Gain depends on the web's wrap angle on the measuring roll and the orientation of the
load cells. Therefore, Wrap Gain depends on the actual installation.
This gives:
T (tension) = Wrap Gain F
There are two ways to find out the ratio between web tension and measured force on the load
cells, by Hanging weights or by Calculation.
With hanging weights (Menu HangWeight)
•
String a rope that follows the web path exactly and apply a known weight.
The applied known weight simulates the actual web tension and the electronics measures
the resulting force on the load cells caused by the applied weight.
When both web tension (T) and the corresponding measured force (F
tension electronics calculates the ratio T / F
When web tension is applied to the roll the tension electronics calculates web tension by
multiplying the measured force on the load cells with the Wrap Gain.
After the hanging weight procedure the wrap gain calculated by the tension electronics can
be found in the EnterWrapGain menu.
Weight
Figure 3-13. Setting Wrap Gain with Hanging Weights (example of installation)
Tension Electronics PFEA113, User Manual
(force of web tension in load cell measuring direction)
R
and stores the value as Wrap Gain.
R
Load cel l
supported roll
Section 3.12.6 Set Wrap Gain
) are known the
R
All rolls must be
free turning idlers.
To keep friction
losses low, only
use the closest
Rope
rolls to define web
path.
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