Technical advantages of LVDT
What is LVDT?
LVDT stands for Linear Variable Differential Transformer, a type of electromechanical sensor that converts mechanical changes in linear motion into corresponding electronic signals. LVDT linear position sensors can measure displacements as small as 0.1mm and can also measure displacements up to 1000mm. More information aboutLVDT Tutorial
Technical advantages of LVDT
LVDT position sensors derive their unique advantages from their technical principle and construction materials.
Frictionless Measurement
One of the most critical features of LVDT sensors is their frictionless measurement capability. In standard operating conditions, there is absolutely no mechanical contact between the LVDT's core and coil assembly - eliminating friction, stiction, or any other frictional effects. This unique characteristic makes LVDTs particularly valuable for material testing, vibration displacement measurement, and high-resolution dimensional measurement systems.
Endurance extreme environments
The LVDT’s rugged design allows it to operate reliably in harsh environments. Its epoxy-encapsulated coil, housed in a stainless steel tube, provides strong resistance to moisture, humidity, vibration, and shock. Additionally, internal magnetic shielding reduces interference from external AC magnetic fields.
The housings and cores are made of corrosion-resistant metal, and the housing also provide enhanced isolation from magnetic fields. In applications where the sensor must be exposed to flammable, corrosive vapors and liquids, or pressurized fluids, the entire structure of the housing and coil assembly can be completely sealed by fusion bonding process.
Standard LVDTs typically operate across a wide temperature range. However, for extreme environments (such as cryogenic, high-temperature, or nuclear radiation applications), it is recommended to use LVDT sensors without built-in signal conditioners, as electronic circuits are generally limited to -20°C to +80°C operation. ABEK offers various external signal conditioners that can be paired with LVDTs installed in harsh environments, with cable lengths up to 100 meters between the sensor and conditioner.
Infinite resolution
Due to its frictionless electromagnetic coupling design, an LVDT can detect extremely minute core position changes. This theoretically infinite resolution capability is ultimately limited only by the resolution of the signal conditioner & the digitization capability of the output display. While the LVDT signal conditioner output contains minor high-frequency ripple, this occurs at such elevated frequencies that it remains imperceptible in most practical applications.
Infinite mechanical life
Since there is no physical contact between the LVDT’s core and coil assembly, the sensor is entirely free from friction or mechanical wear. This unique characteristic gives the LVDT a theoretically infinite mechanical lifespan—a critical advantage for high-reliability applications such as aircraft, satellites, spacecraft, and nuclear equipment. Additionally, this feature is highly sought after in industrial process control and factory automation systems where long-term operational stability is essential.
LVDTs cannot be mechanically damaged by exceeding their measurement range
Most ABEK LVDT sensors feature open-ended bore designs. In cases of accidental over-travel beyond the nominal measurement range, the core can pass completely through the coil assembly without damage. This unique over-travel capability makes our LVDTs particularly suitable for material failure testing applications, such as integration with extensometers for tension measurement. Recommended models for these applications include the FCNA-FCXA10, FCNA19, FCNA20, and FHNV19 series.
Insensitive to radial variations
The LVDT responds exclusively to axial displacement of the core along the coil's centerline, while remaining inherently insensitive to radial or off-axis movement. This unique characteristic enables reliable operation even in non-ideal mounting conditions, including: misaligned installations, floating/free-moving applications and non-linear motion paths. The sensor maintains measurement accuracy regardless of minor lateral core displacements.
Separable coil and core
The LVDT's unique magnetic coupling principle allows for the insertion of non-magnetic pressure barrier sleeves between the core and coil assembly. The coil assembly is completely isolated from the process medium; this design enables the pressurized fluid remains contained within the barrier sleeve to reduces coil failure risks from fluid exposure. This critical feature is extensively utilized in hydraulic proportional/servo valve position feedback applications. Recommended model FCNA20 series.
Null Position Repeatability
The LVDT's inherent null position is very stable and highly repeatable, even beyond its applicable operating temperature range. This feature makes the LVDT an excellent position sensor option for applications in loop control systems and high performance servo instruments.
Fast dynamic response
The frictionless design enables LVDTs to provide near-instantaneous response to core position changes. The sensor's dynamic response is limited only by the minimal inertial effects of the lightweight core. In practical applications, the overall system response speed is ultimately determined by the output bandwidth of the signal conditioner.
Absolute output
Unlike incremental sensors that require re-zeroing after each power cycle, LVDTs are absolute-output devices. They maintain and provide true position data even through power interruptions—a critical advantage for applications requiring absolute position feedback, such as structural health monitoring, safety valve positioning and servo control systems.
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