25 years of loyal service to London's Royal Opera House

Even before its modernisation, the upper machinery in the Royal Opera House offered an impressive view with its five vertically moving rows of beams, equipped with countless halogen spotlights. In 2000, igus supplied a customised zig-zag energy chain system to safely guide the numerous cables during the vertical movement, which was used reliably and trouble-free until the end.

With the switch to modern LED technology in 2025, however, the requirements changed fundamentally: although the new lights save around 90% energy, they are significantly heavier. As the existing suspension points only have a limited load-bearing capacity, a completely new, lighter support structure had to be developed - including a suitable energy supply system. For this, the theatre brought the stage technology specialist HOF and the igus project planning team on board.

The time window for maintenance and technical innovations is tight at theatres: 4 weeks are available for this between seasons. When the curtain goes up again at the start of the season in September, everything has to run smoothly.

The new lighting hoists, developed, implemented and installed by HOF, now comprise five 21m long rows of aluminium trusses. They can be moved at speeds of up to 250mm/s to a height of over 25 metres. Each row consists of three closely spaced units that can be moved individually. Each unit has a lower truss with the lights and a main truss which is responsible for the load-bearing capacity - and this is where the new e-chain system had to be integrated.

The Royal Opera House hosts up to 285 performances a year and just as many rehearsals. The lighting systems are in constant use from 7am to 11pm. The system must function reliably under this continuous load and also be quiet and visually unobtrusive so as not to disturb the performance.

When the igus team was commissioned to supply the appropriate energy supply system, it initially considered other e-chain systems that are successfully used in stage technology, such as motorised e-spools, in which the e-chains are wound up. Due to the large volume of cables, the zig-zag solution, in which the e-chains fold and unfold, once again proved to be the best option.

The parameters of weight and smooth running were the biggest challenges here. Zig-zag systems generate a slight pendulum impact, which depends on the specific geometry of the system. The large number and heavy weight of the cables exacerbated this effect: Initial tests showed lateral deflections of up to one metre. After prototype tests on site, it was clear that this effect had to be reduced in order to ensure safe and smooth operation. At the same time, the weight of the originally planned guide boxes had to be reduced from 200kg to less than 150kg.

The problem with the pendulum deflection was solved by using reverse zig-zag arrangements of the energy chains. A scaled-down version was successfully tested at the igus headquarters in Cologne: The deflection could be reduced to 20mm, which can only be measured with high-precision laser technology.

Making the guide boxes 50kg lighter: This has also been achieved. The original plan with 2.5mm thick steel baskets was discarded and the material replaced with aluminium. Following a structural and stress analysis, it was also possible to remove additional excess material and reduce the weight to less than 150kg.

Just in time for the installation date in August, igus finally delivered 20 complete zig-zag systems ready for installation, equipped with e-chains of the E4.56 series including cables, to the theatre. The 112kg cable packages contain robust chainflex motor, bus, data, fibre optic and control cables that have been specially developed for moving applications.

In total, there are now nine tonnes of energy chains with a total length of over 1km, which open and close when the lighting hoists travel up and down over 25m - reliably, quietly and inconspicuously as before. We firmly believe that the new systems will surpass the previous ones in terms of longevity.

igus has taken back the previously used energy chains and returned them to the material cycle via the Chainge recycling programme. In this way, 2.4 tonnes of material become a resource again instead of waste. And the theatre has helped to achieve its sustainability goals.