Displacement or convertible values to displacement such as force, pressure, strain, torque, vibrations, etc. can be measured with the inductive displacement transducers which function is based on the linear variable differential transformer principle (LVDT).
These sensors are used in many technology branches (industry, R&D, ...) due to their very good measurement accuracy, the high protection class as well as their long-life duration.
Applications are found in the measurement, regulation and control of slow and fast movements between machine parts, position measurements and position changes of parts components and ground, servo regulators, valve control, robot control, growth measurement, etc.
The construction is robust – the inner coils and electronics are coalesced – so that impulses or vibrations can be endured without problems. As a result, these sensors are suitable for mobile applications (e.g. automobiles) and test stands with high test cycle numbers.


Block scheme

Description

These inductive displacement sensors with integrated electronics contain a differential transformer and a carrier frequency amplifier (oscillator, demodulator, filter and amplifier) that are installed and coalesced in a stainless steel housing.
The supply voltage is in DC and a DC voltage proportional to the displacement is given to the output. The differential transformer consists of a primary and two secondary coils that are arranged symmetrically to the primary coil.
The induced DC voltage in the secondary coils is demodulated, filtered and amplified with the integrated electronic. A rodshaped core is moveable within the differential transformer. In dependence to the position of this core the analog DC voltage supplied to the sensor’s output is changed.
The model 8740 contains an axially free moveable core with two plastic slip rings. These take care of the centering of the core in the perusing drill of the sensor body.
The mechanical coupling of the core with the measurement object can be arranged with clamps or screws. Lateral forces have to be avoided.
The model 8741 features ball bearings to hold the core. The core and its sensing device’s top is pushed against the measurement object with the help of an internal spring. The use of this version is advantageous when the mechanical coupling is either complicated or simply not practical. The measurement side of the sensor is protected against dirt or dust and spray by a rubber bellow.