1. Control, monitoring and safety aspects of electrical distribution in the Atlas experiment W.Iwanski PH/ESE-BE

2. Outline  Overview of electrical supply in Atlas  Evolution of the UPS system  Controlling and monitoring infrastructure  Monitoring applications  Safety of racks’ electronics  Conclusions TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE2

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4. Repartition of power among different Atlas sub-systems  Atlas equipment consumes in total ~ 7 MW of the Regular, UPS and Diesel power during normal operation TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE4

5. Characteristics of the UPS system of Atlas  UPS power is not cut by the AUG but can be cut by the DSS  Primary function of the UPS is to assure power availability during a power cut  UPS is backed up by Diesel generators  In case a Diesel generator fails, a PLC manages shedding of the SDX1 UPS load according to the following profile:  2 h of power is guaranteed for critical users  10 min of power is guaranteed for less critical users TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE5

6. Gas room CV room Racks L1 &2 ESD4/1DX UPS 600 kVA Atlas UPS DieselMains 400V EOD1/1DX EOD2/1DX Racks SDX1 SH1 Cryo SCX1 ACR EOD1/15A EOD3/15A Cryo ctrl roomControl of Magnets EOD4/15AEOD2/15A SDX1 USA15 ESD3/15 UPS 160 kVA Meyrin DieselMains 400V EOD2/15 Racks L2 US15 Evolution of the UPS system in Atlas (1) Cut by the PLC after 10 min (load shedding) TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE6

7. Gas room CV room Racks L1 &2 ESD4/1DX UPS 600 kVA Atlas UPS DieselMains 400V EOD1/1DX EOD2/1DX Racks SDX1 SH1 Cryo SCX1 ACR EOD1/15A EOD3/15A Cryo ctrl room EOD4/15A EOD2/15A SDX1 USA15 ESD3/15 UPS 160 kVA Meyrin DieselMains 400V EOD2/15 Racks L2 US15 EOD5/15A ID racks Muon racks Control of Magnets Evolution of the UPS system in Atlas (2) Cut by the PLC after 10 min (load shedding) Cut by the DSS in case of emergency TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE7

8. Evolution of the UPS system in Atlas (3) Gas room CV room Racks L1 &2 ESD4/1DX UPS 600 kVA Atlas UPS DieselMains 400V EOD1/1DX EOD2/1DX Racks SDX1 SH1 Cryo SCX1 ACR EOD1/15A EOD3/15A Cryo ctrl room EOD4/15A EOD2/15A SDX1 USA15 ESD3/15 UPS 160 kVA Meyrin DieselMains 400V EOD2/15 Racks L2 US15 EOD5/15A ID racks Muon racks UPS 80 kVA EOD6/15A Control of Magnets EOD7/15A Load shedding turned out to be impractical and finally was given up….. TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE8 Cut by the DSS in case of emergency

9. Electronic racks of Atlas  More than 450 racks host Atlas electronics in 4 different zones, some of them are inaccessible during normal LHC operation; all types of power are used to feed the equipment TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE9

10. Basic infrastructure for controlling and monitoring Rack’s supplying boxConcentrating PLC Expert panel Powering switchboards  Concentrating PLC makes state of the system available to the supervising database (CCC) and user application (DCS)  Concentrating PLC provides platform to communicate with the local PLCs in supplying boxes or powering switchboards  Local PLCs execute ON/OFF commands on powering breakers and monitor their state (opened/closed/tripped) LHC Control Room (CCC) Atlas Control Room TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE10

11. Control and monitoring of the racks’ powering Regular supplyUPS” supply Expert panelON/OFFON DCS (Rack Control)ON/OFFON DSSOFF  Type of the control depends on Master  Most of the switch-OFF operations comes from DSS, rarely from an operator, sometimes due to atmospheric conditions (perturbations or power cut)  When power comes back after a cut, all racks stay OFF and need to be re-powered by an operator TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE11

12. Control of supply of the TDAQ computers Powering of 100 racks with up to 31 TDAQ computers in each requires special attention:  Two independent 3-phase powering lines per rack  NTC thermistors on each phase to reduce the inrush current  Each line individually controlled and monitored  PLC-controlled timer disallows immediate back-to-back power re-cycling on the same powering line  Applied solution proved to be reliable and sufficient one. TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE12

13. Electricity Distribution Monitor  Simple but very reliable system, used for monitoring of the electrical infrastructure  Shows status of all electrical supplying cabinets important for Atlas operation  System based on voltage presence sensors being read by the ELMB card interfaced to a local DCS station  Application developed by Atlas and integrated with the global monitoring environment of the experiment TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE13

14. Quality of power supply Event on powering network caused by a turning ON of the SVC filter featuring a glitch down to 50 V and 80 V voltage spike  In general, powering network at Cern is clean albeit occasionally perturbed by the atmospheric storms  Atlas like other experiments has Filters (SVC + TCR) on the Machine network. They, when working, bring a lot of positives : compensation of reactive power reduction of harmonic distortions voltage stability … but when being turned ON, produce disturbances. Their turning ON is coordinated with experiments by CCC TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE14

15. Power Quality Monitor  System monitors state of filters in the experimental zone as well as on the LHC loop  System spies on alarms from the analyzers recording events happening on the 18 kV Machine and GS LHC loop networks  System is ready to monitor signals from local analyzers to be connected to register events on selected 400 V branches  System launches acknowledgeable alarms on the Alarm screen in the Control Room whenever supervised equipment gets activated  Applications developed for the moment for Atlas and Alice experiments. TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE15

16. Safety of the rack’s electronic equipment  Wherever there is an electricity there is a certain risk of fire. Racks hosting an electronic equipment and having a vertical cooling have hardware interlocks cutting the power whenever the temperature or smoke sensors get active.  As an additional protection against fire Atlas developed a control and monitoring system for extinguishers with the liquid CO2 installed in selected racks with the high power or unique electronics: Release of the liquid CO2 to a closed volume of the rack either by pressing a button or when the temperature and smoke conditions are met Veto from the rack’s back door being opened Global enable for each zone from the Atlas Control Room State of all sensors fully monitored by the Minimax System application integrated with the global monitoring environment of the experiment Triggering conditionPress button Back door’s veto Global enable Monitoring of all sensors AtlasSmoke & temperatureYes CMSSmoke & temperatureYesNoYesNo LHCbSmoke & temperatureNo YesNo Comparison of the Minimax Systems developed in the LHC experiments TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE16

17. Conclusions  Atlas being an experiment built from scratch, fully profits from a modern electrical infrastructure building a robust monitoring and controlling systems around it.  Despite being in operation since several years, the electrical infrastructure is still evolving implying adjustments in the monitoring and control systems. Imperfections of the implementations are uncovered by major events.  Applications like the Electricity Monitor or the Power Quality Monitor or the Minimax System developed in Atlas bring an added value to the monitoring environment developed typically in other experiments. TWEPP conference, Vienna, 28/09/2011 W.Iwanski PH/ESE-BE17