The Implementation of the power supply system of the CMS Silicon Strip Tracker

The power supply system of the silicon strip tracker of the CMS experiment provides HV bias and LV power to the 15000 modules of the detector, arranged into 1944 “power groups” and 256 “control rings”. Around 1200 power supply modules, disposed on 29 racks, operate in a “hostile” radiation and magnetic field environment, 10 m away from the beam crossing region. They power the detector through≃ 50 m long custom-designed “Low Impedance” cables, adopting the sensing wire technique to compensate voltage drops. Detector “power groups” and “control groups” are powered bymodules of different architecture,which are fed by 48 V sources, provided by AC-DC converters installed in the racks. This paper reports the experience acquired in the implementation of the system, the rack layout, the grounding scheme, the power budget, the heat dissipation on racks. A comprehensive Quality Assurance program ensured the performance, using a well defined protocol, shared with the board’s manufacturer, for acceptance tests and failure detection.