Abstract--More than 6DO switch mode power converters are installed in LEP to power the Main Ring Magnet System. The horizontal and vertical corrector magnets are fed oy 520 bipolar, four-quadrant units of 675 W output rating. The short chains of quadrupole and sextupole magnets with copper windings are powered by 105 modular resonant type power converters of a d.c. output rating of 37.5 kW. Their transformer-coupled outpirt stage allows to choose three different output ratings, i.e.: 300 A/125 V, 200 A/188 V and 150 A/250 V. Eight high current 2000 A, 10 V converters feed the super-conducting quadrupoles for the low-13 insertions in the physics interaction regions. Details will be given on the initial CERN design work leading to the choice of circuit topology, in order to meet the strict accelera-tor requirements, particularly on efficiency, size and reliability. The converters were purchased from European Industry on the basis of precise performance specifications. High power switch mode converters of compact design and high efficiency are by now an established technology, which offers attractive tech-nical and economic solutions for powering conventional and stiperconducting magnet systems
