Transformer oil is prone to microbial contamination during storage, utilization, and transportation, which affects the quality and insulating performance of transformer oil. In this study, the effects of temperature and humidity on the microorganism growth in transformer oil were mainly investigated, and the quality changes of transformer oil before and after treatment were analyzed. The functional group structure and organic species of transformer oil were identified, and some effective treatment methods for microbial pollution in transformer oil were proposed. The results show that both the transformer running oil and faulty oil contain bacillus subtilis, bacillus using sugar to produce acid, bacillus using sugar to produce acid and gas, and bacillus producing acid and gas without sugar. The number of microorganisms in faulty oil is much greater than that in running oil, and the number of bacillus subtilis is the largest, while there is no microorganism cultured in new transformer oil. The high temperature could restrict the growth of microorganism in transformer oil. When the temperature is 60℃, the microorganisms will not be completely inactivated, and once the temperature returns to 37℃, they will start to grow and reproduce again. When the mass ratio of oil and water is 99∶1, 49∶1, 19∶1, and 9∶1, four types of bacillus all exist at 37℃, and the number of bacillus increases with the increase of oil-water mass ratio. The regeneration treatment method of high-pressure sterilization+molecular sieve coarse filtration+ultrafiltration can make the contaminated transformer oil clear and transparent, and the microorganisms disappear. The regenerated oil mainly contains O-H, C-H, C=O, and unsaturated bonds. After regeneration treatment, the breakdown voltage and volume resistivity of transformer oil increase from 25.83 kV and 5.70×1010 Ω·m to 49.50 kV and 4.68×1011 Ω·m, respectively, and the dielectric loss factor decreases from 6.052% to 0.215%, which meet the requirement of DL/T 1419—2015.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |