Strain sensor solution for the wind energy industry

Martin Weigert, general manager of Avago’s Industrial Fiber Product Division, commented: “Avago Technologies has supplied large quantities of POF cables and communication modules for industrial networking and data communication applications, and has amassed a significant amount of experience in both markets. By leveraging that experience, the development of the industrial optical sensing technology is a natural extension of the company’s core competence, allowing the company to address a fast growing market. Our proprietary optical phase interrogation method has enabled us to offer a disruptive strain sensing solution using POF—a worthy alternative to conventional strain sensing technologies, electrical and optical, for a number of applications.”

Suitable applications for the strain sensor solution include wind-blade load management in wind turbines and structural health monitoring for a variety of other structures. Engaged in mulitple wind energy applications, Avago is currently installing sensors into a multi-megawatt conceptual turbine for both wind blade and tower load monitoring. In this market the technology offers a rugged alternative to conventional strain measurement technologies.

Employing the POF to form a “meander path” sensor array, the optical sensor allows a single fiber to form multiple loops. Fitting into a confined area, these loops will alter the phase of an optical signal injected into the fiber when strained. Comparing the reference signal to the strained signal, a separate non-strained reference loop surrounds the meander path. The difference in phase between the two signals can be converted into the strain measurement, while the reference fiber simultaneously provides temperature compensation.

Containing only optical fibers, the sensing array is immune to EMI and EMC related interference and is completely electrically isolated from the rest of the system.

Helping designers test and evaluate the sensor technology, Avago has assembled a developer’s kit consisting of a length of polymer optical fiber, the optical phase interrogator, and all the necessary documentation. Enabling developers to create a strain sensor with the fiber and evaluate the results, the developer kit will be available in January 2014.