In the world of industrial automation, accuracy is everything. Whether it’s robotics, aerospace, or manufacturing, the need for precise displacement measurement is non-negotiable. That’s where LVDTs, or Linear Variable Differential Transformers, step in. These devices are widely used in applications requiring high resolution and repeatability.
What Is an LVDT?
An LVDT is an electromechanical transducer designed to measure linear displacement. It works on the principle of mutual induction and converts the linear motion of an object into an electrical signal.
How LVDTs Work
The device consists of a primary coil and two secondary coils wound on a hollow cylindrical former. A movable ferromagnetic core, which doesn’t touch the coils, moves within the cylinder. When the core moves, it alters the magnetic flux, changing the voltage output of the secondary coils.
Key Components
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Primary Coil: Receives AC excitation.
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Secondary Coils: Generate output voltage based on core position.
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Movable Core: Transfers the position data magnetically.
Why LVDTs Are So Reliable
LVDTs are contactless, frictionless, and highly durable. Unlike resistive sensors, there’s no wear and tear, ensuring a longer operational life.
Types of LVDTs
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Unguided Armature Type
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Captive Armature Type
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Spring-Extended Armature Type
Each type has unique benefits based on the application, such as dynamic range, mounting method, or environmental resilience.
Common Applications
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Aerospace actuator testing
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Industrial automation
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Railway track monitoring
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Medical equipment
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Hydraulic system feedback
Advantages
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Absolute linearity
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Infinite resolution
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High sensitivity
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Rugged construction
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Maintenance-free operation
Limitations to Consider
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Sensitivity to temperature
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Requires AC excitation
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Core alignment is critical
Final Thoughts
The linear variable differential transducer has become indispensable across industries that rely on precision. As automation evolves, LVDTs will continue to play a vital role in enhancing control and feedback systems.
