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PS and crates service

PS and crates service

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PS and crates service

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  1. PS and crates service Issue observed on some Wiener LVPS internal power lines & other news…

  2. PS and crates service • Outline • Wiener LVPS internal power line issue • Observed problem • Analysis and discussion with Wiener • Outcome and recommendation • Water cooled PSU and cooling network cleanliness • Short preventive maintenance status report • Caen purchase contract and forecasts

  3. PS and crates service • Wiener LVPS internal power line issues – Observed problem • Observed during the modification of 4 water-cooled Atlas-TRT LVPS by Wiener • Some power wires (connecting the PS output plug to the modules) have been found with melted and cracked insulation material • Potentially concerned: • All Maraton and PL5xx LVPS with an output current of 50A and above.

  4. PS and crates service • Wiener LVPS internal power line issues – Analysis and discussion with Wiener • First assumption from Wiener: Related to the wire isolation material causing oxidation of individual copper strands followed by overheating. • Wiener changed this wire for a tinned version on units produced after 2007. • Discussion on the wire cross-section: • According to EN standards 10mm2 are required for 50A (Wiener internal wire: 6mm2) • Wiener explained that for short distances the wire can be assimilated to PCB tracks. Wiener provided a copy of the TUV CE certification tests (according to the EN-60950 standard). • Safety concern: Wiener states that this internal wire issue presents no risk for users nor risk of inflammation. Each PSU channel is self protected against over currents and overheating (PS level). • Wiener did not observe other occurrences of damaged power wires, but did measure high resistance values on checked wires.

  5. PS and crates service • Wiener LVPS internal power line issues – Analysis and discussion with Wiener • Wire loss measurements were performed on a few PSUs (of different types and used in different setups). • Measurement method • Disconnected sense lines and no local sense jumpers (on-module internal regulation). • Voltage measurement on the output connectors with and without load. • Delta V is directly related to the internal wire loss. • Different LVPS types have different internal wire lengths and layout Sense lines disconnected Local sense jumpers removed DVM measurement Connection to load

  6. PS and crates service Wiener LVPS internal power line issues – Measurement results

  7. PS and crates service • Wiener LVPS internal power line issues – Outcome and recommendation • The source of the problem is not yet fully understood. Possible origins: • Aging effect on the wires • Related to the operating conditions (temperature, absence of airflow / installation in confined space) • No other occurrences of damaged wires was observed so far. • Next steps and recommendation: • Perform material analysis on the broken wires (Goal: confirm Wiener suspicion on the corrosion effect of the isolation material) • Monitor the stability of the wire resistance over time • Users/experiments to perform further internal voltage drop analysis • Select a few PSUs (if possible different types, operational conditions and produced before/after 2007) • Perform the measurements presented on the previous slides regularly (for example during every technical stop) on the selected units. • Share your results with the PS service • Re-assess the situation yearly

  8. PS and crates service • Water cooled PSU and cooling network cleanliness • Wiener and Elcotron reported this on several occasions • Important amount of metallic particles found in the water cooled LVPS. High risk of clogging the 4mm PSU cooling circuit. • Degraded connector seal resistance to pressure (when disconnected) • Recommendation for the PSU • Purge all PSU with compressed air • Clean the internal PSU cooling circuit with clear water • Repeat the operation twice • Some ideas for the cooling network • Inspect/change the rubber tubes • Install magnetic filtering systems • Use an alternative fluid? Internalview of a rubber tube (from CMS) Metallicdustfoundwhilecleaning a PSU

  9. PS and crates service • On going preventive maintenance campaign (focus on Wiener equipment) • Atlas Status: On going Total: 287 units Done / in progress: 180 • CMS Status: On going Total: 349 units Done / in progress: 200 • LHCb Status: To be scheduled Total: 143 units • AliceNA Total: none • New request : BE-CO wants to have 200 VME PSU maintained preventively before the end of LS1. Details to be received and discussed • Current issues: • Shortage of shipping boxes for equipment shipped back to Wiener • Internal CERN transportation takes longer than expected • Will have some impact on the schedule • Many thanks for the good cooperation so far.

  10. PS and crates service • Caen purchase contract and forecasts • Caen purchase frame-contract B1226 status • Running until end of 2019 • Spent so far: 4.4 MCHF • Remaining CERN budget code expenditure shall not exceed 380 kCHF until 2019 • Make effort to spend on team money • Purchase forecasts for the coming years is required from the experiments and users. Particularly if CERN budget codes are planned to be used. • Electronics coordinators please assess exceptional purchase needs (if any) for LS2.