1. Vir korozivnega žvepla v transformatorskem izolacijskem olju
Izolacijsko olje, ki se uporablja v transformatorskem energetskem sistemu, je večinoma rafinirano iz naravnega nafte. Kemična sestava nafte je razmeroma zapletena. Ni sestavljen niti iz enega samega elementa niti iz preproste spojine, ampak je mešanica več spojin, sestavljenih iz številnih elementov.
Transformer oil manufacturers retain a small amount of sulfur in the oil, using its function as a natural oxidation inhibitor. Under normal circumstances, sulfur compounds can slow down the aging rate of the oil and prevent the formation of acidic substances and precipitates. The finished transformer oil The total sulfur content is generally below 0.5 percent . The sulfur and sulfide in the oil are divided into two categories: "active sulfur" and "inactive sulfur". Active sulfur mainly includes elemental sulfur, hydrogen sulfide, and mercaptan, which can directly react with metals. , has high corrosiveness, and the rest are called inactive sulfur, mainly including sulfide compounds, alkyl sulfides, cyclic sulfides and sulfonic acids. Higher levels of mercaptans are found in low-refined imported transformer oils of the type with no added antioxidants or with added trace amounts of antioxidants.
2. Škoda korozivnega žvepla v transformatorskem olju
1. Mehanizem tvorbe bakrovega sulfida v transformatorskem olju Hitrost korozije merkaptana na baker narašča z naraščanjem temperature. Ko se temperatura poveča s 60 stopinj na 120 stopinj, se lahko stopnja korozije merkaptana do bakra poveča približno 16-krat.
Tvorba bakrovega sulfida na splošno poteka skozi tri stopnje:
(1) Površina bakrene žice v transformatorju se oksidira, da tvori film bakrovega oksida.
(2) Film bakrovega oksida reagira s tioli in nastane bakrove tiolate, ki so topni v olju.
(3) Copper mercaptide can be brought to various parts of the transformer by the transformer oil, but most of it is adsorbed and left on the insulating paper by the insulating paper. When the temperature is high, it will decompose to form cuprous sulfide Cu2S and oil-soluble organic residues . The reaction formula of the reaction process is as follows: 2Cu plus O2→Cu2O Cu2O plus 2RSH→2CuSR plus H2O 2CuSR→Cu2S plus RSH where RSH represents a thiol, and R represents an alkyl group. At present, transformers above 220kv are all sealed with capsules or metal expanders, and have been vacuum degassed before being put into operation, but a small amount of oxygen will remain in the transformer oil. Standard and the dissolved ratio of oxygen and nitrogen in the transformer oil (about 3:7), the oxygen content in the oil is allowed to be 3000uL/L, so theoretically, the above reaction will occur in any oil-immersed transformer.
2. Vpliv bakrovega sulfida na izolacijske lastnosti transformatorjev
Bakrov sulfid je mikro-prevodna snov in njegova prevodnost je veliko višja od prevodnosti izolacijskega papirja in transformatorskega olja. Proizvodnja bakrovega sulfida v transformatorju se sprva odlaga na površino bakrenega prevodnika tuljave v navitju. Trenutno je usedlina bakrovega sulfida manj škodljiva in ni dovolj, da bi povzročila delno razelektritev in kratke-nesreče med zavoji in plastmi. Ko pa transformator teče, bo s tokom transformatorskega olja tuljava neprekinjeno prečiščena in več usedlin bakrovega sulfida se suspendira v transformatorskem olju in se adsorbira na izolacijski karton. Ko ustvarjeni bakrov sulfid doseže določeno količino, bo bakrov sulfid, adsorbiran na izolacijski karton, spremenil porazdelitev električnega polja znotraj transformatorja in zmanjšal odpornost na napetost tuljave v navitju. Pod določenimi delovnimi pogoji pride do delne praznjenja znotraj navitja, izolacijskega materiala se pokvari in resnega obloka, kar povzroči nesrečo izgorevanja transformatorja.