The presence of moisture & contamination due to arcing can be extremely harmful to the reliability of the tap-changer and the transformer.
The oil filter unit cleans and dries the switching oil while the transformer is in operation, their by extending maintenance interval of Tap changers.
In its cylindrical tank, the pump unit contains the feed pump, the pump motor and the filter cartridge.
The flange connection for the oil feed /return pipes are installed on the upper and the lower covers of the tank. This ensures clear arrangement of the pipes between pump unit and on-load tap-changer head.
A pressure switch and a manometer monitor permissible working pressure. A temperature switch is available for low temperature operation as a special feature.
Easily accessible when the upper cover is removed, the filter insert is simple to replace when necessary with the existing lifting handles.
The pump unit is connected by pipes on the on-load tap-changer head. The head is equipped with the flange connection for oil feed (suction pipe) and oil return.
With each diverter switch action, the Oil Filter System automatically handles the filtering and drying of the switching oil. The pump motors starts up and suctions the oil in to the oil filter via the suction line of the on-load tap-changer and the pipe. The oil enters the filter tank from the bottom and is pressed with the feed pump through the filter insert. The purified oil leaves the pressure tank from the upper cover and flows back through the pipe to the on-load tap-changer head.
The working pressure between feed pump and filter insert can be read with the manometer. This working pressure increases with the time due to the accumulation of solid materials in the filter insert. When the increasing pressure exceeds the set maximum value, the filter insert must be changed. When the pressure switch triggers, a signal contact is activated this tells the control room that the maximum value has been reached.