Patented fengyu designed tc on line oil purifier device, with its added feature of transformer loading-switch, has the capacity to eliminate the following industry problems. Switches on large transformers widely installed on-loading switches with frequent on-load switching can produce arcs which will lead to oil cracking, free carbon and water, which deteriorates oil quality, will lower oil dielectric strength, limit switching frequency of switch, and even endanger the safety of transformer operation. The tc loading-switch on-line oil purifier device is used to bypass circulation filtering of on-load switch. It can choose timing filtering or oil filtering after switching the regulator opening under the condition of the transformers normal operation. The device can remove free carbon, water, and oxide material when it is circulation filtering. This feature will ensure the quality of switching oil, keep the dielectric strength of switching oil, increase the frequency of switch, extend maintenance cycle, reduce the number of blackouts, guarantee the quality of voltage and improve the security and reliability of load-switching. The apparatus of the tc loading-switch on-line oil purifier device is installed in a stainless steel cabinet controlled by the programmable timer without requiring supervision. It is fixed on the side of loading-switch and also has accessories with various flowrate and different functions. Technique dex rated pressure: 0.5 mpa inlet/ outlet diameter: on 15 overall dimension: 280x680x1000mm weight: 120 kg rated flow: 10l/min electric power: 250w power supply: 380v/220v 50hz function feature remove free carbon from oil. Remove water from oil. Raising oil dielectric strength. Lower wear of contact point. Increase the switch frequency. Extend maintenance cycle. Extend the life of insulating oil. Reduce the number of blackout. Guarantee the quality of power supply.