In-depth research is made on technology of intelligent online oil filtration for OLTC of power transformers. It shows that technology of continuous diffluence is propitious to high precision filtration under high flux and a 3 L/min filtration power can guarantee an ideal filtration for 300 L oil. A PLC

type LOGO230RC

is used to intelligently control the online filtration process; 100 W anti-burn heater is combined to a temperature and humidity controller to prevent circuits from dew. And electronic motor protection relay is used to protect the motor completely. Airproof connections in oil circulation

air exhaust at initial installation and filter change

as well as the improvement of configuration layout by 3D visual design are also discussed.