Position sensors come in a variety of types and have different operating principles. Each specific sensor meets the requirements of a particular application. Perhaps one of the most popular kinds of sensor used across industries is an LVDT or linear variable differential transformer. An LVDT converts the mechanical motion of the object attached to it into electrical signals. In measuring rectilinear displacements, LVDTs can effectively function detecting movements as minute as millionths of an inch.
Working principle and sensor design
An LVDT has a simple and straightforward design. It consists of a hollow tube with three winding coils. These coils are wound around the tube often made from glass reinforced polymer. A cylinder housing covers the mechanism protecting it from moisture and other elements. The contactless design of LVDTs makes them ideal for broad industrial application, especially when there is exposure to harsh working environments.
History of LVDTs
Before the 1930s, position sensors like LVDTs were not widely used. It was not until the beginning of World War II when engineers started considering the application of LVDTs in laboratory equipment as well as in processing. At that time, LVDTs would have been beneficial in many applications; however, not many engineers subscribed to the advantage of using them.
One engineer, Herman Schaevitz began researching the potential of LVDTs and wrote a paper about the variety of applications for the device. His research paved the way for the commercial manufacture of LVDTs used by engineers today.
Advantages of using LVDTs
There are many reasons why an LVDT is a popular sensor to use in commercial and industrial applications. When it comes to temperature range, an LVDT can operate in temperatures ranging from −60 to 200°C. By changing the fabrication material, the temperature range expands from −200 to 500°C.
Using alloys consisting of cobalt, nickel, and chromium further extends the functionality of an LVDT in conditions exposed to sulphuric compounds and high temperatures. LVDTs with this characteristic work well in applications including power plants, oil and gas exploration, fuel-rod gauging in nuclear plants, and aircraft engines. In these environments, other types of sensors will not function or survive.
Besides high temperature, the robustness of LVDTs makes them suitable for high-pressure applications. Examples include underwater oil and gas exploration.
Modern uses of LVDTs
Today, LVDTs exist in a variety of applications. Since it is a robust and non-contact position sensor, rugged and industrial applications prefer using them over other types of sensors.
LVDTs will most likely remain popular for use in emerging markets such as wind power generation, and nuclear power generation. LVDTs will also apply to underwater working conditions such as water management and safety.
New technology used in reducing the body length of an LVDT has also paved the way for its application in hydraulic cylinders. Manufacturers also continue to innovate to address past challenges so that LVDTs today have increased measurement accuracy and easier calibration. On top of all these advancements, Manufacturers need to maintain competitive pricing for such sensors to remain a viable option for most industrial and commercial applications.