te/mpe/ee - lhc knud 8/3/2012 project for upgrade of the electrical circuits, the powering scheme...
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DESCRIPTION
TE/MPE/EE - LHC Upgrade of the QPS Electrical Systems of the DYPB’s Reasons for the proposed changes: 2. Powering: The LV powering scheme for energizing the detector electronics of the iQPS system for the main magnets (DQLPU crate) was built and has remained non-redundant from a UPS point-of-view, also after the introduction of the nQPS system which was designed with UPS1/UPS2 powering redundancy - The DQQDS (SymQ) system will, to a certain extend, act as back-up for the ‘asymmetric’ detection of iQPS in case of a failure of UPS1 (now UPS2). However, with the higher thresholds longer detection time can be expected. - The change to a UPS-redundant powering scheme would require important changes to the DQLPU motherboard and back-panel. The ‘crash program’ of 2008/9 did not allow such modifications. The update of the local protection unit would be an appropriate occasion. - Although considered very reliable, the commercial ‘Syko’ tri-volt, switched-mode converters used in the DQLPU s have recently shown some weaknesses (~25 units did not restart after repowering this winter and some evidence that the current rushes observed on the F3 UPS net are caused by the ‘Syko’s’). - The 872 CERN-made (QPS/EPC) linear power supplies with four output stages (the Power-Packs DQLPUS) have worked impeccably for two years and could be the model for a new version of converter suitable for the iQPS upgrade. - It would be interesting to integrate the signal and power patches, introduced with the nQPS, into a new interface (shuffling) module required for the upgrade.