A Design For The Temperature Monitoring System On The Current Transformer (CT)’s Secondary Circuit Using Optical Fiber Sensor

When the secondary of Current Transformer (CT) is disconnected from its load,there will be a high voltage across the open secondary into the range of severalkilovolts. It is hard to find this open secondary circuit in routine operations by oureyes.Nowadays, most open secondary circuits are found by infrared temperaturemeasurement through patrols by inspectors or in maintenance, instead of when theevent happens.The purpose of this paper is to suggest a system based on the softwareLabVIEW and the hardware such as the optical fiber grating temperature sensor,which monitors the temperature at the terminals of the secondary. The system shouldhave powerful functions to include, but not limited to, the temperature data capturingof each monitored point, data processing, data storage, data transmission, audible andvisible alarm. Finally this system will allow us to determine the open circuit events ofthe secondary.Firstly,this paper analyzes in detail the innovation of global optical fibertemperature sensor technology. It then studies and summarizes the research and theapplication of the fiber-optical, optical fibre temperature sensor, virtual instrument inthe electrical power system. Secondly, instead of the traditional approach oftemperature sensors, the paper focus on the introduction of the theory of optical fibergrating temperature sensor and methods of fiber grating wavelength demodulation,and the institution of the hardware structure of the system. Finally, the paperintroduces more comprehensively the software of LabVIEW’s characteristics and itsapplication. Then each interface and operation of the temperature monitoring systemis chiefly introduced. The paper describes the design and the function of each moduleas well as the overall debugging test also.The proposed system provides the opti-fiber temperature monitoring andLabVIEW programming functions. The open circuit on the secondary is indicated bythe temperature monitored. This better man-machine interface allows graphical and tabular displays. For immediate and noticeable warning, audible and visual alarmscan be set according to temperature intervals at different monitoring points.Meanwhile, the data captured can be reported to communication port or he centralcontrol system. The data stored also supports the service engineers’ further inspectionto the equipment.