There are only two methods for measuring transformer oil micro water in China: one is represented by "GY-12 Insulating Oil Micro Water Tester" produced by Wuhan Guoyi, and the other is "GY106 Trace Moisture Determination" produced by Wuhan Guoyi. The "instrument" is the representative, and the two products are now compared; the test principle adopted by the "GY106 Trace Moisture Analyzer" product is: Karl-Fischer Coulomb's method. The principle of this method is very complicated. It was used 30 years ago and has never been used. The big change is based on the principle that when water is present, iodine is reduced by sulfur dioxide. In the presence of methanol, pyridine iodate is generated. During the electrolysis process, the generated iodine generates hydroiodic acid with the water in the sample. Until the reaction of all the water is completed, the instrument uses a pair of platinum electric test panels for sampling, and reagents must be added during the test, which is complicated and time-consuming. The accuracy is low, and the advantage is that the price is cheap. This test method has been used for 20 years. Most of the domestic methods have used this method. The price is cheap. The instruments that use this test method are very easy to identify. There are glassware on the instrument. This method is used. Another kind of "GY-12 Insulating Oil Micro Water Tester" adopts the "sensor method". With the advancement of technology, foreign sensors for measuring insulating oil micro water have been developed, which is only in the past two years. After launching, their company used the German excellent company (HTM2500B 3C40 IL binding oil moisture content sensor), the test method is very simple, put the sensor in the oil, 10 seconds, the test result comes out, the unit is (PPM) The test time is short, the operation is simple, the repeatability and accuracy are very good, and the service life is long. The disadvantage is that the cost of the sensor is high, which causes the price of the instrument to be relatively high. Enterprise), this equipment is about 5,000 to 8,000 more expensive than the Coulomb method equipment.