Abstract
The engineering application number of fiber optic current sensor (FOCS) is decreasing year by year since 2012 in China due to its reliability problems. However, the researchers and related enterprises have also made some constructive attempts on the study of fault diagnosis of FOCS. In this paper, the application status and the common fault modes of FOCS are analyzed. Three ways to diagnosing the soft and hard fault of FOCS are reviewed, including based on analytical model, on signal processing and on knowledge. Finally, the research direction of FOCS fault diagnosing is prospected. It is concluded that the diversified and intelligent fault diagnosis method based on knowledge has more advantages compared with the other two methods. In addition, the development of FOCS for integrated optical path is of great help in improving its reliability and will be a research hotspot in the future.