Type WDG is a drum type de-energized tap changer. It is often designed by the combination of one single-phase and one two-phase tap changers. These two tap changers are to be installed in the clearance between the three winding in one transformer, which is a dramatic saving of transformer space and oil.
Type WSL De-Energized Tap Changer (herein referred as tap changer) is of in-tank structure and without separate oilcompartment. It is mounted to transformer tank by a tap changer head ange.By the operation method, tap changer can be divided into motor driving at man position, and manual drive mechanismoperating at man position as well as hand wheel manual operation on the top.