Baumer BA IRxx.DxxL - Manual (Page 6)

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4 Functions and definitions
4.1 General function
An analog inductive sensor changes its output value (typically current or voltage) depending on the position of
electrically conductive material in the vicinity of the sensing tip. Hence, it can be used to measure the position
of an object which moves.
4.2 Standard conditions
Both the geometry and the material of the object to be measured have an influence on the analog output
curve of an inductive sensor. In addition, the conductive material which is in the vicinity of the sensor front
face might influence the sensor output. Therefore, the standard measurement conditions are defined as
follows:

Standard object (according EN 60947-5-2): The standard target is defined as a square plate, 1 mm
thick, made of Fe 360 (mild steel). The length of its side is defined as the larger of either the sensing
face diameter or three times the maximal sensing distance as noted in the data sheet. For example:
the standard target for an M12 sensors with 6mm sensing range has a side length of 3x6=18mm. On
the datasheet or the installation instructions the reference target is listed.

Standard installation conditions: In order to have reproducible measurement conditions the standard
installation of these sensors is non-flush, this means there is no electrically conductive material
(except the object to be measured) within the vicinity (2x maximal sensing range) of the sensor front
face. For an M18 sensor with 8mm sensing range, this means for example that the nut may only be
positioned 2x8=16mm away from the sensing face.
The technical data shown on the data sheet are valid for these standard conditions (in particular: linearity and
maximal sensing range).
4.3 Object to be measured
In practice, the geometry and the material of the object which moves (also called the target) will differ from the
standard object. The influences can be estimated as follows:

Size: If the object is smaller than the standard object, the maximal sensing range will be reduced. This
means that the output will reach its maximum at shorter distance. If the object is larger than the
standard object, there will be only minimal influences.

Material: If the material is different from mild steel this will typically reduce the sensing range. The
minimal distance at which a useful signal can be measured will be larger; the maximal sensing will be
smaller. The following diagram shows the influence of the target material: