Introduction
The Swiss Light Source (SLS) is a third generation synchrotron radiation source, which is designed to deliver high brightness photon beams to various experimental stations at the same time. The stability and the reproducibility of the electron beam (electron orbit) is one of the most important properties of the particle accelerator. Therefore about 580 high-precision magnet Power Supply (PS) units for beam control - ranging from +/-7A, +/-20V to 950A, +/-1OOOV - were installed in the SLS (table I).