How to Make Transformer Economically Practical? Part 2
by：SUMWIC Machinery 2020-05-03
3.4.2 Acetylene testing device At 750 degree Celsius high, transformer oil will produce acetylene. The problem of over-high above 1000 degree Celsius and a variety of discharge failure (partial discharge, spark discharge, oil arc fault), acetylene will appear. Acetylene detection devices include degassing Lan, acetylene sensors, control devices, data processing and output. Its feature is by on-site analysis to study the fault trends. 4 Drying moistured transformer on-site Degree of drying is directly affect insulation and other specifications of transformer. Therefore, drying insulation systems is the firstly factor to extending transformer life. After drying transformer which be affected by bump, somethings need to do firstly: 1) whether exposed time in air is over time; 2) whether the damp degree and insulation degree over the requirements; 3) how is color change of silicone air dryer; 4) does wind re-winding; 5) whether transformer oil excessive humidity; 6) whether oil leakage; If there is one of above problems, the on-site drying is needed. Drying methods are as follows: 1) hot oil circulation. It is more effective to less serious moisture. It use hot oil as medium, through eddy current, heating transformer then insulation fiber, make moisture evaporation. This method requires vacuum pumping every few hours. The vacuum level of tank should be under l33Pa. Temperture of circulating hot oil should maintain at 60 ~ 70 degree Celsius. 2) Drying by heat oil spray. It is a commonly method used for on-site drying, suitable for medium and large oil-immersed transformers. This method is to using a special nozzle, spraying atomization transformer oil which heating above temperature 1O0 degree Celsius, on body of transformer to make it heating. Then pumping vacuum to transpire the moisture on body. The needy devices are simple. The method has effective for large transformer on-site drying. 3) Field winding charged drying. It need short secondary winding of transformer, and energize the primary winding, to drying insulation systems by electricity heating effect through primary and secondary windings. This method need use vacuum oil filtration machine to transpire moisture in oil. Comparing the ground insulation resistance from high, midium and low phrase, after drying, the dielectric loss and leakage current of insulation resistance are decrease obviously. 4) Vacuum drying by load on fuel tank and eddy current method. This method is energized field winding on tank to produce vortex of energy. This vortex of energy can increase the internal temperature of tank, so as to heating body. The turns per coil, current and power-on time are as to make temperature of tank at 90 ~ 100 degree Celsius. 5) Zero sequence current drying. It is to choose proper three-phase windings, connected in series or in parallel. The windings of other voltage level are open circuit. Adding zero sequence voltage to choosed winding, to generate zero sequence flux in iron core. The flux closed circuit through tank produces eddy current loss to drying the body. This method is suitable for medium and small distribution transformers drying.