The CERN/LHC energy extraction switches and their arc detector system

To extract the large amount of energy stored in the magnetic field of the LHC superconducting dipoles (8 chains with 1350 MJ each) and quadrupoles (16 chains with about 24 MJ each), opening switches will be used. The switches consist of an array of electromechanical D.C. breakers, specifically designed for this particular application. The opening process transfers the magnet excitation current from the array of eight breakers to the extraction resistors, rapidly deexciting the magnet chain. The arcing behavior in breakers of the array has been studied. In order to facilitate the maintenance of the switches an arc detector has been developed. This paper describes the design of the extraction switches and presents the test results, obtained at the LHC pilot extraction facility.