Passive Transducers: LVDT

Passive transducers are those that do not require any external power source to operate. They convert physical parameters such as displacement, force, pressure, temperature, etc. into a measurable electrical signal. LVDT (Linear Variable Differential Transformer) is a passive transducer that converts the linear displacement of an object into a proportional electrical signal. It works on the principle of mutual induction.

Working Principle

LVDT consists of a primary coil, a secondary coil, and a movable core. The primary coil is energized with an AC voltage, which induces an electromagnetic field. The movable core is connected to the object whose displacement is to be measured. The core moves linearly along the axis of the LVDT, and this motion affects the electromagnetic field. As a result, a voltage is induced in the secondary coil, which is proportional to the displacement of the core.

Advantages

- High accuracy and resolution
- Wide range of measurement
- No electrical power required
- Low hysteresis and drift
- High linearity

Applications

- LVDT is widely used in industrial automation, aerospace, and automotive industries for measuring linear displacement, position, and velocity.
- LVDT is also used in geotechnical and civil engineering applications for monitoring structural deformation and displacement.
- LVDT is used in biomedical instruments for measuring the displacement of the heart and other organs during surgery.

Conclusion

LVDT is a highly accurate and reliable passive transducer that is widely used for measuring linear displacement in various applications. It has several advantages over other types of transducers, including high accuracy, wide range of measurement, and low hysteresis and drift.

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