Linear Variable Differential Transformers (LVDTs) and Rotary Variable Differential Transformers (RVDTs) are two types of electromechanical transducers used to measure displacement or angular position. While both devices are similar in function, there are some key differences between the two. In this blog, we will compare LVDTs and RVDTs to help you understand their differences and applications.
What is an LVDT?
An LVDT is an electromechanical device that measures linear displacement or position. It consists of a primary coil, a secondary coil, and a movable core. When an AC voltage is applied to the primary coil, it generates a magnetic field that induces a voltage in the secondary coil. The voltage induced in the secondary coil is proportional to the position of the core within the LVDT. LVDTs are commonly used in applications where linear position sensing is required.
What is an RVDT?
An RVDT is an electromechanical device that measures angular position or displacement. It consists of a primary winding and two secondary windings that are wound in opposite directions. The rotor of the RVDT is coupled to the rotating object, and the stator is fixed to the frame of the device. When an AC voltage is applied to the primary winding, it generates a magnetic field that induces voltages in the two secondary windings. The voltages induced in the secondary windings are proportional to the angle of rotation of the rotor. RVDTs are commonly used in applications where angular position sensing is required.
LVDT vs RVDT: Comparison
There are several key differences between LVDTs and RVDTs that are worth noting:
Sensing range: LVDTs typically have a sensing range of up to several inches, while RVDTs typically have a sensing range of up to 360 degrees.
Linearity: LVDTs are typically more linear than RVDTs, meaning that their output voltage is more proportional to the displacement or position being measured.
Accuracy: LVDTs are typically more accurate than RVDTs, meaning that they have a smaller error or deviation from the true position or displacement.
Complexity: RVDTs are typically more complex than LVDTs due to their rotating structure and the need for slip rings or other mechanisms to transmit power and signals.
Cost: LVDTs are typically less expensive than RVDTs due to their simpler design and lower manufacturing costs.
LVDTs are commonly used in applications where linear position sensing is required, such as in industrial machinery, robotics, aerospace, and automotive systems. They are also used in medical devices such as surgical instruments and MRI machines.
RVDTs are commonly used in applications where angular position sensing is required, such as in aircraft navigation systems, aircraft landing gear systems, marine navigation systems, and control systems for rotating machinery.
LVDTs and RVDTs are both electromechanical transducers used to measure displacement or position, but they have some key differences in their design, performance, and applications. LVDTs are typically used for linear position sensing, while RVDTs are used for angular position sensing. LVDTs are typically less expensive and more accurate than RVDTs, but RVDTs have a larger sensing range and can measure continuous rotation. Both devices play important roles in many different industries and applications.