RVDT – Rotary Variable Differential Transformers

RVDT – Rotary Variable Differential Transformers are a well-established form of rotary position sensor for non-contact measurement of angle. RVDTs have a solid reputation for robustness and reliability in harsh conditions, and equipment manufacturers in the aerospace, defense, oil & gas sectors typically consider RVDTs as the default choice for high reliability or safety-related applications such as missile seekers, precision avionics and high precision servo controls.

Modern Alternative to RVDTs

However, RVDTs do have a number of disadvantages when compared with inductive encoders. Zettlex IncOders utilise the same physical principles as RVDTs and so exhibit similarly high levels of reliability, robustness and safety assurance within harsh environments. Whereas RVDTs are typically constructed from wire windings arranged as a transformer, Zettlex inductive encoders use printed circuit boards as their main components and, unlike RVDTs, there is no need for separate signal generation and processing electronics. This results in smaller, lighter and less costly sensor constructions providing much greater design and integration flexibility.

Zettlex inductive encoders also offer higher accuracy than RVDTs of comparable diameter and are proven for providing reliable angular position and speed feedback within extreme environment applications. Zettlex inductive encoders are typically supplied with a DC power source and generate an absolute digital signal.

RVDT variable

Fig.1. Zettlex Inductive Encoders are smaller, lighter and less costly than RVDTs, providing much greater design and integration flexibility