The Measuring Technique Based On Pressductor® Technology - ABB PFEA 111 User Manual

1.7 The Measuring Technique Based on Pressductor® Technology
3BSE029380R0101 Rev C
Section 1.7 The Measuring Technique Based on Pressductor® Technology
The operating principle of a force transducer has a great effect on how well it will perform. It
also affects how stiff and vibration-free the entire load cell will be, as well its robustness and
tolerance to overload. All of these factors impact on the design, operation, and maintenance of
the web processing machinery.
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ABB's Pressductor transducer technology produces a signal as a result of changes in an
electromagnetic field when the load cell is subjected to mechanical force. It is an operating
principle that has its origin in a metallurgical phenomenon according to which mechanical
forces alter the ability of some steels to convey a magnetic field. Unlike other types of load cell
technologies, physical movement such as compression, bending or stretching is not required for
signal generation.
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A Pressductor transducer (the sensor inside the load cell) is a simple and elegant design.
Essentially, two perpendicular windings of copper wire around a steel core combine to provide a
measurement signal.
An electromagnetic field is created by continuously feeding an alternating current to one of the
windings. The field is positioned in such a way that, since the windings are at right angles to
each other, there is no magnetic coupling between them when the load cell is unstressed.
However, when the transducer is subjected to a force, as shown in the figure, the magnetic field
pattern changes. A portion of the field couples with the second winding and induces an AC
voltage that reflects the tension exerted by the web on the measurement roll. This voltage - a
comparatively strong transducer signal - is converted by the load cell system's tension
electronics into a system output.
Tension Electronics PFEA111/112, User Manual
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