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Electrical Engineering Expert Group Kick-off
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Description
Recording
https://cern.zoom.us/rec/share/hg434PxZnvnLBjV1h2WcnE4rlI4pgEqGAeqvxx6td41EbaF0cPKh3BSet9uCTrGq.NxAj8qGpT83yJsez?from=hub
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Minutes: Electrical Engineering Expert Group Kick-off
Date: Wednesday 14 October 2026, 14:00–15:00 (Europe/Zurich)
Coordinators: Francesco Bianchi, Lucas Hermida Peña
Present: Francesco Bianchi, Lucas Hermida Peña, Riccardo Vasapollo (CERN), Flavio Nocera (EGO), Barbara Garaventa (INFN Genova), Fiodor Sorrentino (INFN Genova)
Apologies: Guido Visser (Nikhef)
1. Introduction from the Coordinators
Lucas opened the inaugural meeting of the Einstein Telescope (ET) Electrical Engineering Expert Group. It is one of two Expert Groups now established; the other covers Cooling & Ventilation. The group's purpose is to:
- support the evaluation and further development of the electrical engineering work,
- act as the interface between electrical engineering, detector infrastructure and other ET systems,
- provide an ongoing forum for technical discussion and review.
Meetings will not follow a fixed cadence. They will be called when there are open issues, decisions needing expert input, or relevant developments from CERN. Any member can propose a meeting in coordination with the coordinators.
Riccardo Vasapollo announced that he will leave the project at the end of November 2026. A new engineer will take over the electrical engineering work, and a full handover is planned. The coordinators thanked Riccardo for his contributions.
2. Introduction from the Members of the Expert Group
- Flavio Nocera (EGO): Engineer with over 20 years in gravitational-wave instrumentation. He started on Virgo in the late 1990s, worked on LIGO at Caltech on design, installation and commissioning, and returned to Virgo/EGO in 2005. He has broad experience across most Virgo subsystems.
- Barbara Garaventa (INFN Genova): Physicist. Her master's and PhD work was on squeezed light and quantum noise mitigation. Since 2023 she has worked on magnetic noise mitigation for ET. She is drafting guidelines on integrating magnetic noise mitigation into ET infrastructure, with a report due in November 2026.
3. Technical Presentation on the Status of the Electrical Engineering Deliverables
Speaker: Riccardo Vasapollo
Load survey
- Load data is being collected from the relevant system contacts: ventilation and clean rooms (Carlo, CERN), cryogenics and towers (Lucas Hermida Peña, Francesco Bianchi), suspensions (Patrick Werneke), and optics (via Lucas).
- Loads are grouped into three networks:
- a Machine Network for technical systems,
- a General Services Network for lighting and ambient ventilation,
- a Safety Network for personnel safety and critical equipment.
- Data maturity varies between systems. The aim is to freeze load values by the end of 2026.
- In the triangular configuration, the corner stations carry the highest loads. Bakeout produces peaks of around 500 kW along the arms, which makes long-distance supply difficult.
- Indicative peak loads:
- Machine Network: several MW,
- General Services: about 20 MW in total,
- Safety Network: minimal, with a modest increase expected.
System design
- The medium-voltage network design is a coupled problem. Substation locations, backbone architecture, equipment sizing and space demands all depend on each other.
- Tunnel space is the main bottleneck. Three layout options were presented:
- the current baseline, with caverns every 5 km and only two shafts,
- alcoves about every 1 km for distributed substations,
- a combination of the two.
- Uninterrupted low-voltage distribution over 5 km is not feasible under standard industrial practice. The cable trays required would be impractically large and unsafe to maintain underground.
- A technical gallery concept was proposed to reserve space for cable trays. It is inspired by the LHC false floor and fixed scaffolding.
- The study is moving from conceptual to preliminary design. To produce single-line diagrams and a Class 3–5 cost estimate, ETO must decide on space allocation and substation placement: alcoves, additional shafts or a technical gallery.
4. Discussion
Scope: triangle vs. 2L
The current CERN–ETO mandate covers the triangular configuration only, since it is the most complex. Solutions are expected to transfer to the 2L configuration by removing about one third of the systems. The scope may be revisited in the future.
Dependence on the civil infrastructure baseline
Fiodor Sorrentino noted that many electrical requirements are driven by civil infrastructure choices that remain undefined. Riccardo confirmed that substation placement and cable routing cannot be properly assessed without these inputs. Progress on key design decisions therefore depends on a civil infrastructure baseline.
Magnetic noise mitigation
- Barbara requested that magnetic emission KPIs be included in the study. Choices such as substation spacing (5 km vs. 1 km) will strongly affect noise levels near sensitive detector areas.
- She proposed a joint zoning strategy that places transformers, switchboards and racks as far as possible from the interferometer.
- Riccardo agreed. He noted that emissions depend on distance, cable type, shielding and voltage level, and that noisy equipment should be grouped in dedicated electrical rooms. Moving these rooms further away increases cabling cost, so the trade-off is again coupled to civil infrastructure.
- Riccardo proposed involving CERN's cabling section, which has expertise in cable emissions, to review Barbara's report.
Power backup strategy (UPS and generators)
- Lucas asked which systems must remain powered during an outage.
- Fiodor noted that in current detectors, UPS covers most hardware needed for locked operation, while initial vacuum pumping may not need it.
- Flavio compared the two existing detectors:
- Virgo has broad UPS coverage,
- LIGO historically covered only vacuum and accepted operational downtime as long as safety was maintained.
- Riccardo observed that Virgo's backup capacity is two to three times its needs, and that ET's load is about ten times larger. He proposed a selective approach: UPS for critical subsystems (about 40% of load), bridging to generators, and no blanket UPS coverage.
- Fiodor agreed this is reasonable. The final strategy is a decision above the scope of the current study.
- Formal power quality and reliability requirements, such as limits on harmonics and availability targets, have not yet been received.
Action Items
| # | Action | Owner | Due |
|---|---|---|---|
| 1 | Circulate the magnetic noise mitigation guidelines report to the Expert Group for feedback | B. Garaventa | Nov 2026 |
| 2 | Ask CERN's cabling section to review the magnetic noise report | R. Vasapollo | Nov 2026 |
| 3 | Include magnetic emission KPIs in the electrical infrastructure study | R. Vasapollo / successor | Ongoing |
| 4 | Freeze load survey values | R. Vasapollo / successor | End 2026 |
| 5 | Bring the tunnel space allocation decision (alcoves / shafts / technical gallery) to ETO | L. Hermida Peña | TBD |
| 6 | Collect formal power quality and reliability requirements | Coordinators | TBD |
| 7 | Organise the handover to Riccardo's successor | L. Hermida Peña | End Nov 2026 |
Expert Group Meetings