LHC UPS Systems and Configurations: Changes during the LS1 V. Chareyre / EN-EL LHC Beam Operation Committee 11 February 2014 EDMS No /02/2014

Outline  UPS systems and replacement project during LS1  New configuration in the alcoves and LHC odd points  New configuration in LHC even points  New powering interlock rules  EMC considerations  Conclusion 2EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

UPS Systems for the LHC  Critical equipment around the LHC powered by Uninterruptible Power Supply (UPS) systems  QPS (Quench Protection System), Beam Dump System, Beam Loss Monitor, etc.  Machine Protection  Cryogenics and vacuum control systems, power converters auxiliary circuits, etc.  Machine Availability  UPS principle  Continues to provide power to critical loads whenever the input power fails for the time given by the backup battery  Nominal conditions: load powered via the double conversion path  Input source failure: the load remains supplied by the inverter using the battery stored energy  Load automatically transferred to the bypass line in case of:  Internal UPS failure  End of battery autonomy (requires bypass AC source available)  Short-circuit or overload on the downstream distribution (unlikely)  Fully automatic, load transfers < 1 ms 3 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014

LHC UPS Systems Replacement Project  Replacement of the existing APC Silcon UPS systems during the LS1(see EDMS )  Project motivations:  Improve the reliability  Decrease the failure rate  Minimize LHC run time losses  Change of UPS system topology: come back to the conventional double conversion UPS topology (with output isolation transformer) 4 Delta Conversion Double Conversion EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

Basic Requirement for the QPS  Basic requirement for a safe powering: 2 independent power paths and protected by upstream UPS systems  So-called F3 and F4 power lines distributed all along the tunnel  QPS redundant equipment connected to F4 5EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

UPS Configurations before the LS1: Alcoves (REs) and Odd Points  Basic requirement: 2 independent power paths and protected by upstream UPS systems  No link between both UPS units 6 Output UPS power protected  UPSs interfaced with the Powering Interlock Controller (PIC):  Magnet powering stopped when loosing one UPS EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

New UPS Configurations in the Alcoves (REs) and Odd Points  3 rd UPS (UPS backup) powering the bypass of both UPS F3 and UPS F4 = Stand-by redundancy  ‘Natural’ redundancy: no communication bus between the 3 UPS units 7 Output UPS power protected Distribution Unchanged EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

Tolerance to the First Failure  Example: UPS F3 internal failure  UPS F3 transfers to bypass instantaneously  UPS backup takes over the F3 load  2 power paths still protected  After a failure, we come back to the same situation as today (but with conventional UPS systems!) 8 Output UPS power protected Output UPS power NOT protected  Failure of a second UPS in the same zone will stop the magnet powering (PIC triggered) EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

UPS Configurations in LHC Even Points (Before 2009) 9  2 parallel-redundant UPS systems in:  UA (IP left side)  US  UA (IP right side) EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

UPS Configurations in LHC Even Points: before LS1 10  Redundant QPS equipment powered from the UPS system located in the adjacent zone  F3 and F4 lines always powered from 2 different redundant UPS configurations (one in US, one in UA)  Allowed to preserve parallel-redundant UPS systems in UAs and USs  Was already tolerant to the first UPS failure (in each zone) EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

New UPS Configurations in LHC Even Points 11  Distribution remains unchanged  Standby redundancy applied in UAs and USs  F3 and F4 lines still powered from 2 different redundant UPS configurations (one in US, one in UA) EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

Tolerance to the First Failure (in each Zone) 12  Example: failure of the first UPS in UA  Transfers to bypass instantaneously  UPS backup takes over full load in UA  Redundant power paths still protected  Failure of one UPS in the adjacent zone (US in this case) is allowed  Failure of 2 UPS units in the same zone will stop the magnet powering (PIC triggered) EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

New Powering Interlock Rules  One single UPS failure = 2 power paths still protected = No PIC triggered  New rules:  Magnet powering can continue upon one single UPS failure  Machine can start with 2 UPS systems out of 3 in the alcoves and LHC odd points  Machine can start with one UPS system out of 2 in the UA and US zones  New UPS configurations allows to wait for the next stop for repairing an UPS failure  Gives us more time for preparing and optimizing the intervention  UPS redundancy restored (and improved)  Increases availability for all users, including EN-EL for fault repairs 13EDMS No /02/2014 LHC Beam Operation Committee Changes in UPS Configurations

New UPS Systems – EMC Considerations  APC Silcon UPS systems well-known to produce noise at 8 kHz  High frequency noise caused by switching transistors (IGBTs) for creating the sine wave at the output  Switching frequencies varies according to the UPS manufacturer and the design  New UPS specified according to applicable standards (IEC )  With the objective of attenuating perturbation at around 8 kHz: reduce noise level or shift it to higher frequencies (MHz frequencies are damped by distribution cables) 14 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014

New UPS Systems – EMC Performance  Industrial double conversion BORRI UPS selected from invitation to tender  New UPS fully compliant with required standard (IEC : EMI and EMC)  CERN internal (re-)qualification of the new UPS with the help of TE-EPC  Noise immunity (UPS = victim)  Burst immunity (high frequency, low power): within IEC standards  Surge immunity (lightning, high power): very good (2 x IEC standard levels)  Noise emission (UPS = aggressor)  EMC conducted noise on AC input/output lines created by the UPS: within IEC standards  UPS output (< 100 kHz): the peak at ~8 kHz (now at ~7 kHz) is reduced by a factor 5  UPS output (> 100 kHz): another peak appears at ~1.3 MHz (but still 4 times lower than the existing at 8 kHz) 15 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014

EMC Performance Comparison 16 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014 1MHz 8kHz

EMC Performance – Situation Assessment in the Tunnel 17 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014 UPS output Downstream distribution switchboard Downstream distribution switchboard with UPS OFF Local distribution in tunnel with UPS OFF 5 m 150 m

Conclusion  Change of UPS system topology:  Conventional double conversion topology much more reliable  New UPS system network configuration  Delocalization in points 5, 7 and 8 (R2E project)  UPS network majorly improved during LS1:  Safe powering for machine protection system with independent and redundant paths  Availability increased for all users and thus for LHC operation  Tolerance to the first UPS failure in each zone  Noise in the 8 kHz range reduced with new UPS systems  Noise in the MHz range: ‘false’ problem since noise is attenuated along the distribution cables  Up to now: ~80 new UPS BORRI installed and in operation on surface and underground, no problem reported today  Filtering solution (MHz) being studied with TE-EPC 18 LHC Beam Operation Committee Changes in UPS Configurations EDMS No /02/2014