The LVDT working principle
LVDT stands for Linear Variable Differential Transformer. The LVDT is an analogue and non touching sensor with one primary and two secundary spools. With the linear movement of the tappet, an electrical sigal is produced. Attached to the tappet, there is the ferromagnetic core. The core induces tension into the secundary spools.Construction of a LVDT ( PDF 100 KB)
Amature = core + core extension unguided, guided or as a taster function
The core inside the LVDT is attached to the pushrod, which is directly connected to the measured application.
The amature is attached to the application, but still moves free inside the LVDT. The correct axial alignment is important. The pushrod moves without any contact.
A guided amature is guided using a maintenance-free bearing.
Amature as a tasterfunction:
The pushrod is guided using maintenance-free bearing. It is pushed out with an integrated feather.
Amature on both sides:
The amature can come out of the back of the LVDT. This makes sense especially in very dirty environmental conditions, so the dust can not settle inside the housing. According to that, this serves the mechanical protection when the application takes a bigger mechanical way that the displacement.