Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Environmental Aspects EMC, radiation, UPS… Etienne CARLIER AB/BT/EC

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Outline Electrical Distribution –Architecture –Protections EMC –Emission –Immunity –Shielding Radiation

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Electrical Distribution Architecture The LBDS kicker electrical distribution is based on a combination of –Normal supply for power components (power supplies…), and –Uninterruptible supply for control components (SCSS, BETS and TSDS). High voltage and low voltage power supplies are conform with the CE regulations.  Normal power distribution system instabilities will not disturb operation  A pulse to pulse reproducibility of +/- 0.1% is guaranteed for a +/-10% mains variation, a 2% asymmetry between phases and a 3% variation of the mains frequency. Surveillance of the electrical distribution system is included in the SCSS

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Normal / Uninterruptible Supply Failure BETS Uninterruptible supply (UPS) failure  BETS reaction time is not deterministic  Detection delay depends of impedance of electronics circuits, failure sequence of micro- controller, low voltage power supply hold-up time….  BETS will fail due to the absence of power and issue a dump request (fail-safe logic)  A detection of the UPS failure faster than 80ms is achieved through a continuous surveillance of the UPS voltage Active fail-safe redundant logic UPSNormal supplyUPS BETS Reference BETS Interlock Dump Request Kicker Power Supplies Normal supply failure  BETS reaction time is deterministic  Extraction trajectories are guaranteed within operational limits through the beam dump energy tracking interlock  Detection delay depends of the sensitivity of the BETS interlock windows, generator impedance, HV power supply hold-up time, machine mode and energy…

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Normal / Uninterruptible Supply Failure TSDS Active fail safe logicPassive fault tolerant redundant logic Normal Supply Failure  Uninterruptible supplies guarantee the correct propagation of the dump request up to the HV generator. UPS Dump request distribution uses the “domino effect” Energy required to distribute the dump request up to the kicker HV generator is –Pre-stored within capacitor at each stage of the triggering chain, –Used to trigger the next stage, and –Checked before a beam permit signal is issued Uninterruptible Supply Failure (UPS)  Detected at the fail safe logic stages (“Client Interface”)  Propagation of the dump request to the HV generator relies on the ability of each passive stage of the triggering chain to maintain their output power capabilities in a correct operational windows during at least the 100  s following the detection delay,  An additional asynchronous beam dump will be triggered through a RTD unit 100  s after the detection delay. Dump Request Receiver Abort Gap Synchronization Trigger Fan out Power Trigger HV Generator

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Electro-Magnetic Compatibility General Ready state: 99,99999….% of the time (Pulse Period) –Immunity to external electromagnetic perturbations Pulse state: … % of the time (Pulse Duration) –Emission of electromagnetic perturbations Kicker = Fast Pulsed Magnet Fast Transient [  s] High Current [kA] Pulse Period + Duration Low Impedance [  H & m  or  ]

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Layout ElectronicHigh Voltage Generator Coaxial Transmission Line Magnet

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Assumptions EMC perturbations issued by kicker systems are mainly in the High Frequency domain and are generated only during the “Pulse State”. Components used in kicker systems and connected to the power distribution systems (mainly high voltage and low voltage power supplies) are conforming with the CE regulations and with the IEC norms for EMC emission & immunity and for Safety: –IEC / EN for EMC emission, –IEC / EN for EMC immunity, and with –EN for safety. No specific measures implemented for immunity and emission through the connections to the mains networks (Normal and Uninterruptible). No sensitivity to Low Frequency EMC perturbations is expected.

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Operational Parameters Extraction Kickers [MKD] Dilution Kickers [MKBH & V] Current Pulse Rise Time Max. dI/dt * Max. Switched Power * Operational Range 16 kJ Max. Peak Current * 270 kA Current Pulse Duration 17.6  s [H] 33.7  s [V] >100  s (1.8 ms) 96 kA/  s 450 GeV  7TeV >100  s (0.5 ms) 100 kA [H] 150 kA [V] 5.5 kA/  s [H] 4.7 kA/  s [V] Signal Spectrum 10 kHz  300 kHz 13.8 kHz [H] 12.5 kHz [V] * Value rated per system Number of generators / system 154 [H] 6 [V] Cable Return Resistance * 0.05 m  0.3 m  [H] 0.2 m  [V] 10 kJ [H] 18 kJ [V] 2.8  s

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Interconnections Electrical distribution Computer network Machine timing system Machine protection system Access system Beam instrumentation Radio-frequency Power converter Vacuum system Cooling …  A lot of possibilities for EMC coupling !!!

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Interconnections (cont.) Electrical distributionTN-S (3PH + N + E) Computer network??? Machine slow timing systemCommon mode Machine protection systemFibre optics + opto-coupler Access systemIsolated Floating contact Beam instrumentationCommon mode (PU) + Isolated blocking oscillator (Trigger) Radio-frequency/prepulseFibre optics Power converter Fibre optics Vacuum systemIsolated Floating contact …  Try to “isolate” as much as possible interconnections between systems

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Perturbations Immunity Kicker systems within the UA will be sensible during the “Ready state” to electromagnetic fields (if any) generated by other equipment due to ground loops. –Ground loops in the vertical plane exist and are composed by the high voltage generator, the transmission line, the magnet and the earth common mode impedance between RA & UA. –No possibilities to “physically” reduce these loops (…integration issues).We have to live with them and act on the electromagnetic field sources (if any). Immunity of trigger (re-trigger) systems to external perturbations has to be guaranteed (UA63  UA67). –Use of shielded cables and differential transmission for re-trigger signals. –Use of low impedance (50  ) coaxial lines for trigger signals. –Possibility to shield cable ladders in order to increase effectiveness of the cable ladders protection against external perturbations.

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Perturbations Emission Generation of common mode voltages across RA & UA grounds / earths by the coaxial transmission lines during “Pulse State”: –Transmission lines are composed of a set of parallel coaxial cables (impedance reduction), –During the current pulse, a voltage difference is issued between both ends of the transmission lines due to the transfer impedance of the coaxial cable screen and to the cable’s screens skin effect for the return current, –This difference of voltage generates a common mode voltage between RA and UA grounds / earths. This voltage is proportional to the current in the transmission line and to the ratio of the cable transfer impedance and the earth common mode impedance. “Ground jumps” across RA & UA during “Pulse State”: –During a current pulse, part of the current (typ. 0,01% of Imax) will flow through the earth circuit and generate “ground jumps” between RA and UA proportional to the earth common mode impedance

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Perturbations: Emission (cont.) Radiated Emission –The difference of current between inner and outer conductors of the coaxial transmission lines generate an electromagnetic field around the transmission line itself Cable ducts [UA  RA] Transmission Line Cable ladders [UA & RA]

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Perturbations Emission (cont.) Equipment sharing the same earths in the UA & RA will be affected by Conducted Emission perturbations during kicker “Pulse State”: –Differential measurements will / can guarantee signal integrity. Cables crossing / passing near kicker transmission lines between UA and RA will be affected by Radiated Emission perturbations during “Pulse State”: –Good cable shielding will / can protect the signals Levels for Conducted Emission and Radiated Emission are difficult to quantify at this stage: –Measurements from prototype installations exist but coupling effects between generators will not be negligible –Quality of the earth system in the UA, in the RA and between UA & RA has not yet been quantified. The Conducted and Radiated Emission levels depend partially on this parameter.

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Protection Grounding and Shielding Use EUROPA crates with ALODINE 1200 surface treatment for electronic hardware Grounding through an equipotential environment in the UA Extension of the equipotential up to the front of the rack through low impedance mechanical solution Measure cables properly shielded in the cable’s ducts (parallel to the transmission lines) between UA & RA with a simple steel tube

Etienne CARLIER, LBDS Audit, 28/01/2008 LBDS Radiation Electronics for the control of the LBDS kickers is located in the UA –80% digital  Most critical (single event corruption) –20% analogue Electronic is always located below the level of the cable ducts between UA / RA  Passive shielding with concrete No special protection implemented –No worries for electronics in the UA after the test in TCC2 in 1999/2000 before decision For the SCSS the situation is safe  a failure in one of the “SAFE” component will automatically issue a dump request. Redundancy helps. Probability to have a simultaneous “single event” affecting redundant components is low…