# Differences between LVDT and RVDT

This article gives an overview of the LVDT sensor (Linear Variable Differential Transformer) and RVDT sensor (Rotary Variable Differential Transformer) and describes the differences between LVDT and RVDT. Both the sensors are displacement or position sensors, but the common advantages of these sensors mainly include little friction resistance by small resistive forces, hysteresis, low-output impedance, susceptibility is low for noise as well as interferences, solid construction, and tiny resolution is achievable.

## Differences between LVDT and RVDT

One of the major and common differences between LVDT and RVDT is that the LVDT transforms the angular displacement to an electrical signal, and other differences are discussed below which includes what are LVDT and RVDT, construction, working principle, advantages, disadvantages, and its applications.

### What are LVDT and RVDT?

The acronym of LVDT is a Linear Variable Differential Transformer, and it is one type of electromechanical sensor used for altering linear motion into an electric signal.

The acronym of the RVDT is Rotary Variable Differential Transformer, and it is an electromechanical transducer that gives an inconsistent AC output voltage that is linearly comparative to the angular displacement of shaft input. When activated with a set AC source, then the o/p signal will be linear in a particular range above the angular displacement.

### Construction

The construction of the LVDT transformer includes two windings like a normal transformer namely primary and two secondary. Both the windings of the secondary have an equivalent number of twists, and that are connected in sequence with each other. The primary winding is located among the two windings of secondary.

The construction of RVDT comprises one primary winding as well as two secondary windings. The function of rotator displacement is nothing but the e.m.f induced in the secondary windings of the transformer, and these windings are located out of phase to each other for producing an e.m.f.

### Working Principle

The working principle of LVDT is mutual induction. When the primary winding of the transformer thrilled with an AC supply at 1 KHz to 10 KHz frequency then it generates a magnetic field in the middle of the transducer that induces an electrical signal to the secondary windings based on the core position.

The working principle of RVDT is same like an LVDT, based on the shaft movement three different conditions will be formed.

#### Advantages of LVDT and RVDT

There are some advantages of LVDT as well as RVDT which include the LVDT uses low power, and have highly-sensitive, roughness, low hysteresis, and wide range. Whereas the RVDTs are durable, low cost, easy to handle the parts, and the size is compact.

#### Disadvantages of LVDT and RVDT

There are some disadvantages of LVDT as well as RVDT which include the LVDT has a temperature effect which can cause the performance effect, huge primary voltage generate distortion in output, and sensitive to lost magnetic field. Whereas in RVDT, the source of light must be changed from time to time.

#### Applications of LVDT and RVDT

The applications of LVDT, as well as RVDT, mainly include LVDT can work as a minor transducer, and used for measuring weight, pressure, and force. It can be used for displacement dimension ranges from the division of millimeter to few centimeters. Soil strength can be tested, etc. Whereas RVDTs are used in servo control systems in military, fire control, radar, sonar, antenna, avionic, robotics, instruments, naval and navigation networks, GPS (Global Positioning System) as well as navigation systems, etc.

## Key Differences between LVDT and RVDT

The key Differences between LVDT and RVDT include the following.

• LVDT stands for linear variable differential transformer whereas RVDT stands for rotator variable differential transformer.
• The shape of the LVDT is rectangular whereas the RVDT is cam shaped.
• The main function of LVDT is to alter the linear motion to an electrical signal, whereas RVDT is used to calculate the angular displacement.
• The input voltage of LVDT is 1 volt to 24 volts RMS whereas in RVDT will be up to 3V RMS.
• The measuring the range of LVDT is ranged from ±100μm to ±25cm whereas in RVDT will be up to ±40ᵒ.
• The sensitivity of the LVDT is 2.4mv for each volt for each degree of rotation whereas the RVDT ranges from 2mv to 3 mv for each volt for each degree of rotation.

Thus, this is all about LVDT & RVDT introduction, the difference between LVDT & RVDT, construction, working principle, advantages, disadvantages, and applications of LVDT and RVDT.  From the above information finally, we can conclude that LVDT is used to calculate the linear displacement whereas RVDT is used for calculating angular displacement.