Patent ID: 7193336

Claim:
An electrical lead for connection between a higher temperature and a lower temperature, said lead comprising: a first buss at said lower temperature, said first buss having a cross-section area A for current flow therethrough; a second buss at said higher temperature; n first leads in parallel, each first lead having a first end and a second end and connected at said first end to said first buss, each said first lead having a cross-section area for current flow, the sum of cross-section areas of n−1 of said parallel first leads being less than said cross-section area A; n second leads in parallel, each second lead having a first end and a second end and connected in parallel at said first end to said second buss, each said lead having a cross-section area for current flow; a controllable interface unit connected between said first leads and said second leads, said interface unit selectively connecting electrically said second end of any one of 0, 1, 2 . . . n of said n first leads to said second end of a respective one of said n second leads, in use current flowing between said busses through said connected first and second leads, in use heat flowing from said second higher temperature buss to said first lower temperature buss through said connected leads, said interface unit selectively disconnecting said connected leads electrically with a physical gap between said second ends of said disconnected leads, electrical current and conductive heat flow being blocked across said gap.