Karl A. Knappe and Christian Hirschmüller of UEFA Technical Services in Nyon discuss the EMC aspects of low voltage installations in stadia in this special online article.
Continuous development, a keyword especially in the broadcast industry on major sport events, is on-going. Production standards like HD, 4K, 5.1 audio among many others increase the complexity in setup and operation to a new maximum. The complete changeover to digital production workflow, new media technology and extended coverage of an event leads to highest data rates and requires bandwidth on the ‘lifelines’ inside and outside of a stadium. On the other side, these systems are highly sensitive to disturbances from their respective electrical environment.
UEFA Technical Services observes and analyses this coexistence and the influence of electrical systems on broadcast and event production in stadia since a longer period. It is evaluating best practises to guarantee a state-of-the-art TV production without any instability and ensuring electrical safety.
What is the problem?
Large broadcast configurations are influenced by transients caused from low voltage networks especially under unsymmetrical and rich harmonic load conditions – which is the normal realistic standard in every modern day-to-day operation.
The consequences on the broadcast side:
Loss of audio and video signals, instability in data signals caused by jitter and re-sync effects. In fact we are confronted with a well-known issue called EMC: electromagnetic compatibility. Even though it is taken into account for sensitive areas like data centres or hospitals since years, it is not established for stadia with broadcast and event production – this regardless of broadcast systems being supplied by the stadium or independent generators.
Further analysis in many venues brought to light that mostly low voltage systems based on TN-C and TN-C-S causally create a noise floor of rich high frequency distortion that is distributed by multi bonding of neutral conductors to earth in the whole building.
Of course, for safety reasons, it is mandatory in electrical networks like TN and TT to earth the neutral. Even strict equipotential measures are necessary. But stray currents caused by multi bonding or use of TN-C networks have dramatic effects on the stability of broadcast and event technology, building control systems and other networks. Increased corrosion of metal elements like tubes or reinforcing bars is a further side effect.
What is the solution?
After years of testing and analysing different technical solutions under live conditions as galvanic isolation of certain broadcast areas or using harmonic filters solely, the use of TN-S networks from the sources to the last end distribution under consideration of all details mentioned in the worldwide regulation of IEC 60364-4-44:2007-08 finally solves the problem completely.
Modern stadia are in fact a ‘data house’ considering the dimension of digital equipment that is used for sports, concerts or other events this especially in view of the additional installation of temporary equipment to run the production. Technology moves on but some standards for electrical systems are not on eye level with the technical developments.
Experience from recent tournaments:
UEFA EURO 2008™ in Austria and Switzerland was affected by several problems caused from TN-C and TN-C-S circuits, e.g. loss of audio signals on the media tribune due to the use of an elevator at the back of the tribune.
For UEFA EURO 2012™ Poland and Ukraine UEFA Technical Services took a clear decision for the implementation of an IEC 60364-4-44:2007-08 conform system in all eight stadia and was fully put into practice. All temporary supply systems were even designed in the same way.
The result and the feedback UEFA received from several broadcasters were outstanding: “The first time in the history of major sport events there were absolutely no problems with signals and power”.
High-class and state-of-the-art production of events at modern stadia demands a distinct attention to the special requirements of the equipment. Contemporary design of electrical networks for these buildings must also follow the rules of EMC.
As safety in electrical operation is the most important rule for the design it is not easy to find the ‘right’ way to combine these two worlds: Safety and EMC. IEC 60364-4-44:2007-08 formulated a safe and reasonable way which is also proven by practise.
Based on our experience and keeping in mind that broadcast technology developments will continue an installation following EMC rules at stadia hosting state-of-the-art broadcast and event production will be mandatory in the future. This technical solution is now a UEFA requirement for UEFA EURO 2020™ stadia. Other sports organisations also comply with EMC conformity for their upcoming major events. Therefore we see a new standard in electrical low voltage installations to ensure a future failure free broadcast and event production.
For further information please contact Christian Hirschmüller, UEFA Technical Services & Overlay Manager, email@example.com
© 2007 IEC Geneva, Switzerland. www.iec.ch
IEC 60364-4-44 ed.2.0: Single bonding of N and PE in a TN-S multiple feeder arrangement to avoid a stray current loop.
The authors thank the International Electrotechnical Commission (IEC) for permission to reproduce Information from its International Standard IEC 60364-4-44 ed.2.0 (2007). All such extracts are copyright of IEC, Geneva, Switzerland. All rights reserved. Further information on the IEC is available from www.iec.ch. IEC has no responsibility for the placement and context in which the extracts and contents are reproduced by
the author, nor is IEC in any way responsible for the other content or accuracy therein.