LVDT Technology Overview
Linear Variable Differential Transformer (LVDT) sensors are electromechanical transducers that convert the linear motion of a mechanically coupled object into a corresponding electrical signal. These position sensors can be used to accurately measure linear motion and are sensitive enough to measure movements as small as a few millionths of an inch.
LVDT Coil Assembly
The diagram below shows the components of a typical LVDT. The transformer’s internal structure consists of a primary coil winding centered symmetrically between two identical secondary coil windings. The coils are wound on a one-piece hollow form of thermally stable glass reinforced polymer, encapsulated against moisture, wrapped in a high permeability magnetic shield, and then secured in a cylindrical stainless steel housing. This coil assembly is usually the stationary element of the position sensor.
LVDT Core
The moving element of an LVDT is a separate tubular armature of magnetically permeable material called the core, which is free to move linearly within the coil assembly’s hollow bore.The core is mechanically coupled to the object under measurement. Typically, the bore of the coil assembly is large enough to provide enough radial clearance that there is no physical contact between the core and coil assembly.
LVDT Operation Explained
In operation, the LVDT's primary winding is energized by alternating current of appropriate amplitude and frequency, known as the primary excitation. The LVDT's electrical output signal is the differential AC voltage between the two secondary windings, which varies with the axial position of the core within the LVDT coil. In this way, as the object coupled to the LVDT core moves, the movement is converted into a corresponding AC output voltage. Usually this AC output voltage is converted by suitable electronic circuitry to a high level DC voltage or current that is more convenient for the user.
LVDT Applications
LVDT (Linear Variable Differential Transformer) sensors are widely used in various industries and applications due to their precision, reliability, and durability. Some common applications for LVDT sensors include:
- Automation and Robotics
- Material Testing
- Aerospace and Aviation
- Civil Engineering
- Power Generation
Overall, the versatility and accuracy of LVDT sensors make them suitable for a wide range of applications across different industries.
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