Measuring Principle Of The Sensor; Mounting Arrangement; Coordinate System - ABB PFCL 201 User Manual

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2.5
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Measuring principle of the sensor

The measuring principle of the sensor is based on the Pressductor
the permeability of a magnetic material changes under mechanical stress.
The sensor is a membrane machined in the load cell. Primary and secondary windings are wound
through four holes in the load cell so that they cross at right angles.
The primary winding is supplied with an alternating current which creates a magnetic field around
the primary winding. Since the two windings are at right angles to each other, there will be no mag-
netic field around the secondary winding, as long as there is no load on the sensor.
When the sensor is subjected to a mechanical force in the direction of measurement, the propaga-
tion of the magnetic field changes so that it surrounds the secondary winding, inducing an alternat-
ing voltage in that winding.
The control unit converts this alternating voltage into a DC voltage proportional to the applied
force. If the measurement force changes direction, the sensor signal changes also polarity.
Figure 10. Propagation of magnetic field around secondary winding due to mechanical force on sensor

Mounting Arrangement

When choosing a mounting arrangement it is important to remember to position the load cell in a
direction that gives sufficient measuring force (F
The load cell has no particular correct orientation; it is positioned in the orientation best suited for
the application, bearing in mind the positions of the screw holes. The load cell can also be installed
with the roll suspended under the load cell.
The load cell has the same sensitivity in both tension and compression, so the load cell can be
installed in the easiest manner.
Typical mounting arrangements are horizontal and inclined mounting.

Coordinate System

A coordinate system is defined for the load cell. This is used in force calculations to derive force
components in the load cell principal directions.
Pressductor PillowBlock Load Cells, Vertical Measuring PFCL 201, User Manual
) to achieve the highest possible accuracy.
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