RVDT and LVDT Comparison: Key Differences, Advantages, and Applications

 

Position sensors are widely used in many industrial applications. For many decades now, RVDT and LVDT are considered to be two of the most reliable sensor technologies available. What sets them apart from other sensor technologies is their relative resistance to the effects of friction and noise interference. Depending on the construction, an LVDT and RVDT are highly suitable for rugged working conditions.

What is the difference between an LVDT and RVDT?

An RVDT or rotary variable differential transformer is a device that measures the angular displacement of an object and produces an AC output with direct comparability to the angular movement. On the other hand, an LVDT or linear variable differential transformer is an electromechanical device which converts the rectilinear motion of an object into electrical signals.

Difference in construction

Similar to a regular transformer, an LVDT consists of two primary windings and a core. Similarly, an RVDT has the same assembly comprising of a primary coil and two secondary coils. An RVDT works through mutual induction. What this means is that when a steady supply of AC flows to the primary winding, the resulting magnetic field will induce electrical signals in the secondary coils according to the shaft position.

Advantages of using an RVDT and LVDT

RVDT and LVDT sensors have several advantages which make them preferable for applications subject to rugged conditions. Both types of sensors offer a wide range of measurement and use low power. Both are also highly sensitive but do not get easily impacted by hysteresis. The compact size of these sensors makes them easy to install and handle, and they are relatively low-cost devices.

Key characteristics that differentiate an LVDT from an RVDT

Here are some of the key attributes of an LVDT and RVDT that distinguish one from the other:

• An LVDT is rectangular, while an RVDT is cam-shaped.
• When it comes to function, an LVDT converts linear motion into an electric signal, while an RVDT calculates an object’s angular motion.
• An LVDT works at a voltage input of between 1-24 Volts RMS. On the other hand, an RVDT works at an input voltage of up to 3 Volts RMS.
• The measurement range of an LVDT is ±100μm to ±25cm, while the RVDT measurement range is up to a maximum of ±40ᵒ.

These fundamental differences distinguish an RVDT from an LVDT, but it is an established fact that both of these types of position sensors are excellent solutions for industrial applications.

Practical applications of LVDTs and RVDTs

The frictionless operation of both sensors means that there is minimal chance of losing functional integrity due to wear and tear. The reliability of RVDTs and LVDTs makes them a top choice for engineers looking to find sensors for harsh working conditions. You’ll find these sensors used for many heavy machinery and equipment applications in the mining industry. These sensors are also widely used in process control applications in a wide range of sectors like the military, aviation, transportation, food and beverage manufacturing, pharmaceutical laboratories, robotics research and development, and other similar situations.