High‑voltage and LV infrastructure installation for uninterrupted power at Wales’ national stadium
Project Snapshot
| Project Detail | Information |
| Client | Hi‑Tec / Evans Electrical |
| End Client | Welsh Rugby Union |
| Location | Principality Stadium, Cardiff |
| Project Value | £200,000 |
| Project Duration | 8 weeks (Aug–Nov 2019) |
| Services | HV & LV Electrical Infrastructure, Cable Installation, Containment & Testing |
| Market Sector | Critical Power / Generation |
| Installed Capacity | 4 MW DRUPS System |
| Connection Voltage | 11 kV |
| Powersystems Role | Design, installation, testing, commissioning and SAP switching |
| Powersystems Fact | Powersystems are a NERS‑accredited Independent Connection Provider (ICP) with extensive experience delivering complex HV infrastructure for major UK venues and large‑scale standby generation systems. |
Principality Stadium 4 MW DRUPS Case Study
Download the full Principality Stadium DRUPS Case Study — designed for engineers, developers and technical stakeholders. This summary outlines the 11 kV grid interface, LV supplies, generator cabling, control and EMC systems, and the full programme of HV/LV installation, testing and commissioning delivered by Powersystems for the 4 MW DRUPS installation. The full document provides deeper insight into containment design, earthing systems, protection interfaces and SAP‑managed energisation required to deliver a resilient standby‑power solution for a nationally significant venue, ensuring continuous, high‑integrity electrical performance during major events.
Client & Site Background
The Principality Stadium — formerly the Millennium Stadium — is Wales’ national stadium and home of the Welsh Rugby Union. Hosting 20–30 major events annually and welcoming over 1.3 million visitors, the venue relies on an extremely robust power supply.
Past power interruptions highlighted the need for a resilient on‑site power solution. To address this, the Welsh Rugby Union commissioned a 4 MW Diesel Rotary Uninterruptible Power Supply (DRUPS) system to guarantee continuous power during events.
The Challenge
The stadium required:
- A high‑capacity 4 MW DRUPS system to ensure instant, uninterrupted power
- Integration with the existing 11 kV Western Power Distribution (WPD now NGED) supply
- Installation within a constrained city‑centre environment
- New acoustic engine rooms, transformers and switchgear
- Cable containment across ceilings, floors and limited‑access areas
- Full LV, HV, control and communication circuits
- EMC‑compliant terminations for specialist German‑sourced cables
The system had to be fully tested and commissioned ahead of a major international rugby fixture.
Our Engineering Solution
Powersystems delivered the full electrical infrastructure for the DRUPS installation, including:
- HV circuits and 11 kV terminations
- LV AC 230 V / 400 V power supplies for DRUPS
- 110 V & 24 V control circuits
- Screened EMC‑protected circuits
- Network communication circuits
- Full cable containment systems (ceiling, wall and floor‑mounted)
- Earthing and bonding for all circuits
- HV & LV testing, commissioning and SAP switching
Two Dynamic Rotary UPS units (2 MW each) were installed to provide a total of 4 MW of fast‑start, uninterrupted power.
Project Process
- HV & LV design including containment, earthing and fault analysis
- Construction of cable routes and specialist containment
- Installation of HV, LV, control and network circuits
- Integration of DRUPS engines, transformers and electrical interfaces
- EMC cable termination for noise‑sensitive circuits
- SAP‑controlled energisation and functional testing
- Commissioning in time for international rugby event
Project Facts & Figures
- Generators: 2 × 2 MW DRUPS units
- Installed Capacity: 4 MW
- Connection Voltage: 11 kV
- Response Time: Milliseconds
- Altitude: 295 ft
- 11 kV cabling: 235 m
- LV cabling: 988 m
- Control & signal cabling: 3,400 m
- Use of LSZH (low smoke) cabling
- Specialist EMC cable glands sourced from Germany
- Generators continuously synchronised with grid
- NERS Accredited ICP delivery
Technical Specifications
Electrical Infrastructure
- HV circuits and terminations
- 230 V and 400 V LV power circuits
- Control & instrumentation wiring
- EMC‑screened circuits for generator control
- 110 V DC and 24 V circuits
- Network communication cabling
- HV & LV cable containment systems
- Comprehensive earthing and bonding
DRUPS System Integration
- Engine rooms with acoustic containment
- HV switchroom interfacing with WPD
- Diesel fuel feed and ventilation systems
- Radiator cooling and exhaust systems
Partnerships
Delivered in collaboration with:
- Hi‑Tec – DRUPS equipment manufacturer
- Evans Electrical – Principal contractor
- Welsh Rugby Union – End client
- WPD (Now NGED) – 11 kV network operator
This collaboration ensured seamless integration between specialist DRUPS equipment, HV infrastructure and stadium operations.
Key Risks & Mitigations
- City‑centre, high‑profile venue with limited access – Mitigation: Detailed logistics planning and phased deliveries.
- Tight programme ahead of major international event – Mitigation: Prioritised work sequencing and extended commissioning windows.
- High EMC risk due to specialist circuits – Mitigation: Installation of EMC‑rated cables and glands from Germany.
- High fault‑level environment at stadium HV network – Mitigation: Robust earthing and protection design ensured compliance.
- Restricted working areas inside engine rooms – Mitigation: Custom containment and angled LV terminal box solutions.
- Critical dependency on uninterrupted power – Mitigation: Extensive functional testing and SAP‑supervised switching.
Environmental Considerations
Although diesel is used during peak‑load operation, DRUPS units:
- Only run briefly during events
- Avoid full‑time diesel generation
- Act as highly efficient flywheel‑supported systems
- Provide energy resilience without relying on chemical battery banks
Economic & Operational Benefits
- Guaranteed uninterrupted supply for televised events
- Protection against outages and commercial loss
- Reduced risk of power‑related event disruption
- Highly efficient DRUPS operation with long lifecycle
- Reduced dependence on traditional UPS battery systems
Future Prospects
The DRUPS system was commissioned on time for the Wales vs Barbarians international in November 2019. The system now provides instantaneous, reliable backup generation for all major events at the Principality Stadium.
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Powersystems deliver high voltage solutions for critical power, DRUPS, CHP and standby generation systems across the UK.
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