This work carried out a case practical application of fault diagnosis and preventive maintenance techniques to the oil-immersed distributing transformers in a 10 kV SLWL switching station in Shanghai.By utilizing advanced online moni-toring,data analysis,and fault diagnosis models,various types of faults such as overcurrent,overheating,partial dis-charge,and oil moisture content increment,were successfully detected and diagnosed,with high detection rates and re-sponse time ranging within 94%～100%and 2.5～4.8 s,respectively.The case application achieved reduction in annual failure rate from 5.2%to 1.1%,increase in MTBF from 850 h to 2100 h,reduction in maintenance frequency by 35%,reduction in annual maintenance cost by 38%,reduction in equipment fault-induced power outage count from 10 to 2,re-duction in power outage duration from 50 hours to 7 hours,and increase in power supply reliability rate from 99.5%to 99.95%.Therefore the adopted fault diagnosis and preventive maintenance techniques are potentially effective in improving equipment reliability and power supply stability,and deserve further application.
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