8740, Spring Loaded DC/DC LVDT Displacement Sensor

Inductive displacement sensors using the principle of the differential transformer (LVDT) can be used to measure displacement and, indirectly, magnitudes that can be converted into displacements such as force, pressure, strain, torque, vibration and so forth.

Thanks to the high quality of their measurements, their high protection and long service life, these sensors are used in many technologies (industry, research, development, etc.). Applications include measuring, controlling, regulating and monitoring both slow and fast movements between machine parts, measurements of position and positional changes of components and structural foundations, servo regulators, valve and robot controllers, growth measurements and so on.

Their design is robust - the internal coils and electronics are potted - as a result of which the sensors can easily withstand shock and vibration. This makes the sensors also suitable for mobile applications (e.g. in vehicles) and for test installations where they will be subject to many test cycles.

TASK

In a water bath a structured, metallic mesh is squeezed to a small diameter. The metallic mesh expands again as the water is heated. This extension is to be measured by a very precise inductive displacement sensor, whose rod can move very smoothly within the body of the sensor. The expansion of the sample results in a movement of 15 mm. In spite of the extremely low weight of the sensor bat, it is necessary to ensure that its weight does not affect the measurement.

Solution:

Model 8740, with a measuring range of 25 mm, offers the necessary precision. It can measure the expansion accurately
with its extremely light moveable rod in conjunction with a well-adjusted counterbalance. The optionally modifiable mounting thread allows it to be easily mounted without straining the sensor body. Extending the sensor’s rod by means of a special ceramic tappet ensures that mechanical expansion as a result of temperature changes is almost entirely eliminated.