Package substation in tank with separate chambers

A package substation in which a plurality of elements which constitute a substation including a transformer, low tension switchgear and high tension switchgear, are accommodated in a tank, said tank having an outer surrounding wall, separator walls connected to said outer walls and other separator walls to form separate accommodation chambers which isolate said elements each from the others, and insulation fluids filling said accommodation chambers, said insulation fluids covering the elements which are accommodated in said accommodation chambers and said insulation fluids comprising liquids in said high tension switchgear and transformer accommodation chambers and gas in said low tension switchgear accommodation chamber, the liquid containing chambers being isolated and sealed from the gas containing chamber.