What is the complete form of 'LVDT', one of the most popular electromechanical comparators?

Explanation:

Linear Variable Differential Transformer (LVDT)

Definition: A Linear Variable Differential Transformer (LVDT) is an electromechanical device used to measure linear displacement (position) with high accuracy and reliability. It is a type of transformer that converts the linear motion of an object into an electrical signal. LVDTs are widely used in various industrial and scientific applications due to their precision and robustness.

Working Principle: An LVDT consists of three main components: a primary winding, two secondary windings, and a movable core. The primary winding is located in the center, and the two secondary windings are symmetrically placed on either side of the primary winding. The movable core, typically made of ferromagnetic material, is positioned inside the windings. When an alternating current (AC) is applied to the primary winding, it generates a magnetic field that induces voltages in the secondary windings. The position of the core relative to the windings affects the induced voltages.

As the core moves linearly, the voltage induced in one secondary winding increases while the voltage in the other decreases. The difference between these two voltages (differential voltage) is directly proportional to the displacement of the core. The phase and magnitude of this differential voltage provide information about the direction and extent of the displacement.

Advantages:

• High accuracy and repeatability, making LVDTs suitable for precision measurement applications.
• Robust and reliable, with a long operational life due to the absence of mechanical contact between the core and the windings.
• Wide measurement range, allowing for the detection of both small and large displacements.
• Linearity over a wide range of displacement, ensuring consistent and predictable performance.
• Ability to operate in harsh environments, including high temperatures, radiation, and contamination.

Disadvantages:

• Requires an AC power source for operation, which may not be suitable for all applications.
• Relatively large size compared to some other displacement sensors, which may limit their use in space-constrained applications.

Applications: LVDTs are used in a wide range of applications, including:

• Industrial automation and process control for position feedback in actuators and servo systems.
• Aerospace and defense for measuring the displacement of control surfaces and landing gear.
• Automotive industry for suspension and throttle position sensing.
• Medical devices for precise measurement of displacement in diagnostic equipment.
• Research and development for experimental setups requiring accurate displacement measurements.

Important Information:

Analyzing the other options:

Option 1: Longitudinal Variable Differential Transformer

This option is incorrect because the term "longitudinal" does not accurately describe the functioning of the LVDT. The correct term is "linear," which refers to the measurement of linear displacement rather than longitudinal displacement.

Option 2: Linear Variable Dimensional Transformer

This option is incorrect because the term "dimensional" is not specific to the type of measurement being performed by the LVDT. The correct term is "differential," which refers to the differential voltage generated by the secondary windings in response to the core's displacement.

Option 4: Linear Versatile Differential Transformer

This option is incorrect because the term "versatile" is not a standard term used to describe the LVDT. While the LVDT is indeed versatile in its applications, the correct terminology is "variable," which refers to the variable displacement being measured.

Therefore, the correct option is:

Option 3: Linear Variable Differential Transformer