Patent ID: 8604899

Claim:
Electrical dry-type transformer, comprising: an enclosure; a magnetic core assembly arranged within the enclosure, the magnetic core assembly having a first core limb, a second core limb and a third core limb; at least three coil assemblies, of which: a first coil assembly is co-axially disposed about the first core limb and radially separated therefrom by an axially-extending first inner gas duct situated between the first core limb and the first coil assembly, the first coil assembly having a first outermost coil; a second coil assembly is co-axially disposed about the second core limb and radially separated therefrom by an axially-extending second inner gas duct situated between the second core limb and the second coil assembly, the second coil assembly having a second outermost coil; and a third coil assembly is co-axially disposed about the third core limb and radially separated therefrom by an axially-extending third inner gas duct situated between the third core limb and the third coil assembly the third coil assembly having a third outermost coil; at least two diaphragms arranged within the enclosure, the at least two diaphragms being essentially sealed to the first outermost coil and being essentially sealed to a portion of the enclosure and being arranged for guiding a cooling gaseous fluid in series through the first inner gas duct, through the second inner gas duct and through the third inner gas duct, wherein a horizontal and a vertical portion of each of the at least two diaphragms are connected by a joint portion essentially sealed for the cooling gaseous fluid so as to deflect the cooling gaseous fluid and so as to guide the cooling gaseous fluid during operation to flow inside an extra-coil volume along outsides of the third, second and first outermost coils after having been guided through the third inner gas duct.