Vaporization cooled electrical inductive apparatus

Claim 1

Electrical inductive apparatus comprising: an enclosure; a magnetic core and winding assembly disposed in said enclosure including a lower yoke portion disposed beneath the winding assembly and producing heat during normal operation; a liquid dielectric disposed in said enclosure to a predetermined level, said liquid dielectric being vaporizable within the normal operating temperature range of said magnetic core and winding assembly; a storage reservoir disposed in fluid flow communication with said enclosure; and a gaseous dielectric substantially non-condensable over the operating temperature and pressure range of said magnetic core and winding assembly, said gaseous dielectric being transferable between said enclosure and said storage reservoir in response to pressure within said enclosure provided by the vapors of said liquid dielectric, with said gaseous dielectric filling substantially all of said enclosure at a first predetermined temperature and substantially all of said gaseous dielectric being within said storage reservoir at a second predetermined temperature, which temperatures are within the operating temperature range of said magnetic core and winding assembly; a portion of said gaseous dielectric being absorbed into said liquid dielectric at said first predetermined temperature and released into said enclosure at said second predetermined temperature with a resulting increase in volume of said gaseous dielectric; said enclosure including a bottom surface having a channel portion which defines a recess having said lower yoke portion disposed therein, and which laterally surrounds the yoke portion in said recess in spaced relationship therewith, thereby reducing the free volume of said enclosure, with the space between said lower yoke portion and said channel portion forming a sump for said liquid dielectric thereby reducing the volume of said liquid dielectric necessary to fill said enclosure to said predetermined level, whereby the reduction in both the free volume of said enclosure and the volume of said liquid dielectric reduces the required volume of said storage reservoir necessary to contain substantially all of said gaseous dielectric at said second predetermined temperature, wherein the reduction in the required volume of said storage reservoir is substantially greater than the total reduction of the free volume of said enclosure plus the reduction in volume of said liquid dielectric, said storage reservoir having a required volume which is proportional to the free volume of said enclosure and the volume of said liquid dielectric and is given by: ##EQU2## where V S is the required volume of said storage reservoir, V E is the free volume of said enclosure excluding the volume of said magnetic core and winding assembly, K 1 =(φ-1)/(1-βφ) wherein φ is a ratio of the volume of said gaseous dielectric absorbed per unit volume of said liquid dielectric and β is a ratio of the density of the vapors of said liquid dielectric to the density of said liquid dielectric, V L is the volume of said liquid dielectric, K 2 is a constant equal to (1-β)/(1-βφ), K 3 is a constant equal to T 1 P 2 /T 2 P 1 wherein T 1 and P 1 respectively are the temperature and partial pressure of said gaseous dielectric at said first temperature and T 2 and P 2 are the temperature and partial pressure of said gaseous dielectric at said second temperature.