Linear Variable Differential Transformers (LVDTs) are electromechanical sensors that convert linear displacement into electrical signals. As a type of inductive transducer, LVDTs operate on transformer principles to provide precise, contactless position measurements. Their inherent reliability, infinite resolution, and robustness in harsh environments make them critical in industries requiring high-precision motion control, such as aerospace, automotive testing, and industrial automation.
| Type | Functional Features | Application Examples |
|---|---|---|
| AC-LVDT | Requires external signal conditioning; high accuracy and durability | Aerospace flight control systems |
| DC-LVDT | Integrated electronics for direct voltage output; easier to interface | Industrial automation sensors |
| PCB-Mounted LVDT | Compact design for printed circuit board integration | Medical diagnostic equipment |
| High-Temperature LVDT | Operates up to 400 C with specialized insulation materials | Power plant valve position monitoring |
| Submersible LVDT | Hermetically sealed for underwater/wet environment use | Hydraulic cylinder position feedback |
Typical LVDT construction includes:
Operation principle: The core's position modulates magnetic coupling between primary and secondary coils, generating a differential voltage proportional to displacement.
| Parameter | Significance |
|---|---|
| Measurement Range | Defines operational displacement limits (typically 0.1mm to 250mm) |
| Linearity Error | Maximum deviation from ideal transfer function (0.05-0.25% FS) |
| Resolution | Theoretical minimum detectable displacement (down to 0.1 m) |
| Frequency Response | Dynamic measurement capability (up to 20kHz for AC-LVDTs) |
| Temperature Range | Operating limits (-55 C to +150 C standard) |
| IP Rating | Environmental protection level (IP60 to IP68 available) |
| Manufacturer | Representative Product | Key Features |
|---|---|---|
| TE Connectivity | DC-LVDT 5LV Series | 0.25% linearity, 0-20V DC output, IP68 |
| Macro Sensors | AC16 Series | 0.05% non-linearity, 3kHz bandwidth |
| Honeywell | 976SC Series | Submersible design, 0.1 m resolution |
| DLCI Electronics | Model 3800 | High-temperature capability (up to 400 C) |
Key considerations:
Emerging developments include: