ESS | Power System | | Frithiof Jensen ESS Power System Ion Source, Front-end

ESS | Power System | | Frithiof Jensen Contents Overview of distribution system Substations and their limitations Power quality and EMC Grounding system

ESS | Power System | | Frithiof Jensen Preliminary cable route, 24 kV cables 3

ESS | Power System | | Frithiof Jensen Design principles Standard components, –All MV cables are 240 mm^2, 3-phase cables –HV-switchgear is limited to 25 kA –LV-switchgear is limited to 50 kA –LV-transformers < 2000 kVA in size –MV Network operates in a “star” configuration 4 Redundancy – Two side feed, approx. 10 MVA per “loop” – Power can be re-routed within one substation’s LV switchgear – Transformers are loaded to 60-80% of capacity – Bypass switches to re- route power via SCADA system

ESS | Power System | | Frithiof Jensen Klystron Gallery Cryoplants and Heat Pumps Primary substation Central Utility Building Instruments Target station LINAC Tunnel 5 Target Station Backup Power Plant 20 kV Primary Station 20 kV Distribution Station SEE LNDOM MRP 140/20 63 MW 140/20 63 MW Inst. Hall 1 Inst. Hall 3 Inst. Hall 2 Cryo Test Stand Cryo LINAC Heat recovery Cryo Target Target Station Tunnel N Tunnel S RF power Aux. Power 6.6 kV Distribution Station Block diagram

ESS | Power System | | Frithiof Jensen 600 V 6000 KVA Substations - LINAC 600 V 6000 KVA 400 V 4000 KVA 400 V 4000 KVA 600 V 6000 KVA 20 KV “A” 20 KV “B” 20 KV “B” 20 KV “A” X X ION Source Front End RACKS The 400 V stations supply the LINAC controls. This supply is “separated” from the Klystron Modulators due to potential EMC issues. ESS assumes that the Ion Source can run from a 400 V Station. 80 m MEBT/LEBT/LW U/couplers RFQ DTL (5) RF PWR Front End RACKS

ESS | Power System | | Frithiof Jensen MEBT/LEBT/LW U/couplers Ion source RFQ DTL (5)

ESS | Power System | | Frithiof Jensen

CF/ACC “Dumb” CB’s

ESS | Power System | | Frithiof Jensen Physical layout - Substations Separate substations are used for “Process Power” and “Auxiliary Power” due to EMC Process Power stations provide approx. 5 MVA per unit at 600/690 V Auxiliary Power stations provide approx. 4 MVA and may provide 400 V UPS power 10

ESS | Power System | | Frithiof Jensen EMC-directives Supply voltages –Electrical supply limits are given in SS-EN ”Voltage characteristics of electrity supplied by public electricity networks” EMC – limits for emission and susceptibility –SS-EN – specifies tolerance levels for conducted disturbances in low voltage distribution systems –SS-EN – defines electrical environment and tolerance levels for industrial- and private- distribution systems –SS-EN defines electrical environment and tolerance levels medium voltage distribution systems –An abundance of product-specific standards in the family! 11

ESS | Power System | | Frithiof Jensen What to expect? Nominal voltage400, (600), 690 or 6600 V –Maximum voltage variations+/- 10 % –Typical voltage variations+/- 5 % –Backup power + 10 % / -15 % –Random step changes of 1.5% (increase and decrease) of the supply voltage may occur due to operation of the tap-changers of the main transformers. –Infrequent voltage dips shorter than 150 ms are permitted! Nominal frequency50 Hz, +/- 1 % –Maximum variations50 Hz, +4 % / −6 % –Backup power50 Hz ± 15 % Total Harmonic Distortion, THD –Maximum value8 %, 40’th overtone inclusive –Typical value 2 % –Voltage unbalance < 2 % 12

ESS | Power System | | Frithiof Jensen Grounding The RF Gallery and the accelerator tunnel shall have a dedicated grounding system dedicated to EMC for mitigation of EMI which shall be designed in order to respect the following primary criteria in view of equipotentiality: –Criteria 1 (Conducted noise mitigation):- Between any two points of the EMC grounding system, the maximum RMS voltage difference shall not exceed 10Vrms at a frequency of 1 MHz, when a noise current of 1Arms is flowing between these points through such grounding system; –Criteria 2 (Radiated noise mitigation):- The EMC grounding system shall be able to effectively approximate an ideal grounding plane up-to a frequency of 3 MHz. The rule of λ / 50 shall be applied to determine the meshing size of such a grounding plane. –Specified in: ESS , EMC Grounding System

ESS | Power System | | Frithiof Jensen

Implementation EMC grounding mesh Welded joint Terminal pad

ESS | Power System | | Frithiof Jensen questions Interfaces –Power quality, voltage stability needed (dips), sensitivity to EMC/disturbances. –Is the grounding system adequate? –Power & Voltages required? Presently 400 V is assumed, with a local LV distribution panel as the interface point. –Where is(are) the interface(s)? ESS assumes that we have a connection point at a LV panel. –UPS / Backup requirements? –Electrical CAD system and standardisation.