How an LVDT Works
Send the stroke, output and mounting — we recommend the LVDT type and quote samples.
What is an LVDT and how does it measure position? This one-minute animation shows the primary and two secondary coils, the movable core on its push rod, how the differential voltage and its phase give distance and direction, and how electronics turn it into a DC signal such as 4–20 mA.
Chapters
Key points
- An LVDT has a primary coil in the middle, a secondary coil on each side and a movable core on a push rod.
- With the core centred, both secondaries pick up equal voltages and the difference is zero.
- When the core moves, the size of the difference shows how far, and its phase shows which direction.
- Electronics convert the signal to DC, for example 4–20 mA; the core never touches the coils, so there is no wear.
- SEGMENsensor LVDT sensors: strokes from ±0.5 mm to ±500 mm.
Transcript
What is an LVDT, and how does it measure position?
An LVDT has three coils: a primary coil in the middle, and a secondary coil on each side. A movable core slides inside, on a push rod.
An AC voltage excites the primary. With the core centred, both secondaries pick up equal voltages, and the difference is zero.
When the core moves, one secondary couples more strongly than the other. The size of the difference shows how far the core moved, and its phase shows the direction.
Electronics turn this into a DC signal, such as 4–20 mA. The core never touches the coils, so there is no wear.
SEGMENsensor LVDT sensors: strokes from ±0.5 mm to ±500 mm. Learn more at segmensensor.com.