Fiber Bragg Grating Sensor Measuring The Temperature Of The Windings

In power systems, transformer is very important. Its fault will affect the reliability of power supply and normal operation of system. The long-range research indicates that operational reliability of large transformer depends on the insulation condition to a large extent. Most of the transformers are breakdown, because they lost the reliability of insulation. And the main influencing factor of insulation reliability is the temperature of winding. If the temperature is high, the insulation aging will be fast, and the life of transformer will short. When the transformer is running, the temperature of every part is varied, and the temperature of winding is the highest of all. The insulation aging and broken of transformer will attract turn-to-turn short circuit, then a closed short circuit circulation will appear, more heat will be produced and make the winding temperature rise, even burn out the whole transformer. Therefore, real-time monitoring of winding temperature when the transformer is running is necessary. Fiber Bragg grating contactor is pasted on the winding to monitor the temperature.In this article, the fiber Bragg grating sensor is packaged by pressboard to monitor the temperature of winding. When the temperature of the windings change, the temperature of contactor will change, then the wavelength of the Fiber Bragg grating will shift. The main contents are as follows:(1) According to the structure of the device, the mathematical relationship between Fiber Bragg grating wavelength shifts and the temperature of winding is established. The discussion of the structure indicates the linear relationship between Fiber Bragg grating wavelength shifts and the temperature of winding.(2) The packaged material was chosen, the dimensions of contactor were designed with the length of25mm, width of5mm and height of3mm.(3) Constant temperature trough is used in calibration of the device. Each item of static performance indices of sensor as follows:nonlinearity error:0.79%FS; sensitivity:8.91pm/℃; hysteresis:3.85%FS; repeatability:1.76%FS. (4) The winding-temperature measurement indicates that the device can monitor the temperature of winding. The test of constant load shows that the device can reflect the temperature of winding accurately.