Developing Fiber Optics Moisture Sensors and System used in Transformers and Bushings

湿度和湿度的精确测量有许多应用，特别是监测环境，如农业种子储存，化学，生物医学，食品和电子加工，医院，博物馆和图书馆，通常在大多数建筑物中。在高压工程中，水分测量对变压器油中水分含量的测量具有十分重要的意义。目前，该行业依靠各种测量局部放电（PD）的方法来确定何时需要对变压器进行维修。大多数方法只在损害已经造成时才给出指示。测量绕组绝缘纸和框架中的水分可以在损坏发生之前对变压器进行维修，这将导致更强大的电力系统和相当大的节省。在电传感器等多种技术中，光纤传感器以其体积小、重量轻、易实现多功能传感以及抗电磁干扰等优点而受到越来越多的关注。基于光纤Bragg光栅（FBG）的光学传感器已经得到了广泛的了解和应用。fbg是一种紧凑的内禀传感元件，生产成本相对较低，易于复用，适用于一系列应变和温度传感应用。最近，QPS Photonics Inc.开发了一种使用两种类型FBG的湿度传感器，标准FBG和先进的相移光栅。该传感器是通过在光栅区域上逐渐涂抹10层聚酰胺涂层，并在300℃下固化而成的。涂层接触水分后，吸收水分，轻微膨胀并从固有应变中恢复。本项目的目标是开发一种高灵敏度和高性价比的光学传感器，用于监测高压电力变压器内部的温度和湿度。该项目涉及包装设计和表征传感器的性能，该传感器能够检测到微小的水分痕迹。这将是世界上第一次开发这样的功能，使变压器所有者能够实时了解取决于工作油温度和负载的水分输送情况。

Precise measurement of humidity and moisture has many applications particularly monitoring environmentslike agricultural seed storage, in chemical, biomedical, food, and electronic processing, hospitals, museumslibraries and generally, in most buildings. Moisture measurement in high voltage engineering formeasurements of water content in transformer oil is very important. Currently the industry is relying on variousmethods of measuring partial discharge (PD) to determine when a transformer needs to be serviced. Mostmethods only give indications when damages are already done. The measurement of moisture in the windinginsulation paper and frame allows the transformer to be serviced before damages happened, this will lead to amore robust power system and considerable savings. Among several techniques such as electrical sensors, fiberoptic sensors are capturing more attention due to small size, light weight, susceptible to multifunctional sensingand more importantly their immunity to electromagnetic interference. Fiber Bragg Grating (FBG) based opticalsensors have become widely known and popular. FBGs are compact intrinsic sensing elements, which arerelatively low cost to produce, easy to multiplex, and applicable to a range of strain and temperature sensingapplications. Recently QPS Photonics Inc. has developed a moisture sensor using two types of FBGs, astandard FBG and an advanced phase shifted gratings. This sensor was developed by incrementally applying 10layers of polymide coating over the grating area, and cured at 300 C. The coating upon contact with moisture,absorbs the moisture, slightly expands and recovers from the inherent strain. The objective of this project is todevelop a high sensitive and cost effective optical sensor for monitoring the temperature and moisture inside ahigh voltage power transformer. This project is involved with the design of packaging and characterizing theperformance of the sensor which capable to detect small trace of moisture. This would be the first time in theworld that such a capability will be developed, allowing transformer owners to understand, in real time, thetransport of moisture which depends on the operating oil temperature, and loading.