Moving the stage without drama: reliable energy supply for stage technology with igus e-chains

18 Mar 2020

With moving energy supply systems such as the e-spool and the zig-zag system, complicated stage applications can be implemented even in confined spaces and with high loads

The challenge for every "stage builder" is to create the perfect stage. Every job is different, because stages are not off the shelf. Each one is unique, which means that each and every component not only has to be powerful, durable and efficient but must also fit together perfectly. In order to achieve this you need a competent partner who, on the one hand, understands the specific problems of stage technology and, on the other hand, offers a wide range of products with which any stage application can be realised. Treotham is an expert in the field of energy supply and provider of highly flexible cables for dynamic applications. Treotham’s low-friction maintenance-free plastic products, open up new solutions especially for theatre and stage construction, where there are very demanding technical requirements. These challenges include high loads, such as those found in sound and lighting systems, stage sets or entire stage platforms, which must move safely and reliably. Whether for vertical, horizontal or rotary movement, much has taken place in the theatre since the ancient times. Back then, when the Deus ex machina was still moved by hand using winches and pulleys and purely by physical strength; today a large number of motors and cables are usually used to move stage machinery. However, things that have not changed are the basic challenges of dynamic applications. Physical and technical effects still need to move, but the systems themselves must often remain unseen and unheard. This means that they must operate quietly and out of sight, so as not to interfere with the performance. Ideal solutions for stage technology are well hidden. Cables should be guided invisibly and moved silently. However, there is usually only a small amount of space available. Energy supply systems, data and bus cables must not only be silent and space-saving, but also withstand high dynamic loads. Strength and robustness are therefore necessary properties. The stage technician and engineer need systems that are easy to assemble, require little maintenance, and promise maximum service life. Otherwise the curtain will fall at the most inopportune moment. Treotham offers system solutions that are geared to the special conditions in stage technology. As Treotham provides modular systems and a wide range of igus components, it is possible to implement customised applications quickly and easily. Ideal for an industry where every theatre, every opera and every stage is one of a kind and serial production is not possible.


e-spool: the alternative to the cable reel - without slip ring

Traditionally, cable reeling drums of various sizes are used for cable guidance on stages. However, they are reaching their technical limits in many respects, in particular with the capacity to accommodate different cable types and also the noise generated. The igus e-spool from Treotham provides an operationally reliable alternative that is ideally suited for noise-sensitive applications. The system is extremely compact and is able to guide a large number of different energy, data, control or pneumatic cables in very confined spaces. In terms of design, this is a combination of two proven igus product families, long-lasting e-chains and the flexible "twisterband". The continuous movement of the cables is reliable and safe due to the e-chain. This offers protection from external influences, wear and tensile strain, and significantly increases the service life of the cables. And safety can be further enhanced by using Treotham’s own igus chainflex cables designed specifically for moving applications in energy chains. As part of the readychain product range, harnessed energy chain systems, plug-in connectors and highly flexible cables are available from a single source - complete systems of the highest quality. The e-spool in turn protects the e-chain, which is safely stored on a drum. During the reeling, an integrated retaining spring ensures the correct tension of the chain at all times. The most important innovation is the use of the twisterband, which connects the spool to the shaft end block and forms the interface between fixed and moving cables. In this way, the twisterband allows a continuous cable guidance during rotational movements without needing a slip ring. The slip ring has serious disadvantages due to the sliding contact. The abrasion primarily leads to wear, which in turn worsens the electrical power and signal transmission. If fast and trouble-free data transmission is required, cable drums with slip rings are not ideal and must be "upgraded" with a special accessory. Here the e-spool is much simpler and more efficient, offering a high technical quality.


The e-spool as a solution for upper and lower machinery

Usually, two locations are defined in stage technology: upper and lower machinery. In reality, the e-spool is suitable for both. A key reason for this is its quietness, whereas systems with slip rings can cause noise during operation. As the tests in the igus noise chamber have proven, the e-spool is clearly the better option. With an appropriately equipped e-spool, the noise level could be below 46 dB (A). When it comes to the best signal and sound quality, such as in the upper machinery in Mountford Hall, one of the largest concert halls in Liverpool, the lack of slip rings pays off. There a customised cable guidance system with four e-spools supplies moving power and signals for the entire loudspeaker system so that the best possible sound balance is always achieved in halls of different sizes or during different events. The uninterrupted connection between amplifiers and speakers ensures optimum sound. The e-spools make as little noise as possible and achieve a visually tidy effect. Even with the use of even more e-spools in the upper machinery, the energy supply remains completely hidden from view. At the Culture and Congress Centre in Torun in Poland, a total of ten e-spools are moving the power cables for the lighting trusses. Since the room configuration can be changed, the cables and connections had to be highly flexible and resilient. A requirement profile that the e-spool system was designed for! The Sydney Opera House, too, is already using the e-spool for its upper machinery. But the e-spool is also well suited for the lower machinery, as can be seen at the Cologne Opera House. A total of 18 e-spools are there in the stage pit to ensure the necessary energy supply for stage floor operations. At the same time, all cables for control, lighting technology, the audio and video cables as well as the electrical power supply must be unobtrusively routed. But there is only a very limited vertical installation space available. Conditions that the e-spool meets with its compact design. Routed on the side of the podium legs to save space, they ensure absolutely concealed cable guidance, so that despite their high number there is no visual obstruction and passageways remain free. The stage platform of the Cologne Opera also benefits from the free choice of colours for e-spools and e-chains. All cable guides were kept in neutral black. For safety reasons, yellow was used for the e-spools in the stage pit. In general, there is always the option to choose the colour that best suits the function and the background. All applications in upper or lower machinery show that the e-spool ensures uninterrupted cable guidance with high transmission reliability, even with limited space and tight radii, as well as a minimum of visual and acoustic interference. These plus points also gained the e-spool the iF product design award.


Performance features and variants for the stage such as the e-spool power

The igus e-spool is extremely flexible. It can guide different types of cables and diameters, both vertically and horizontally. Since larger cables can be separated, even cable diameters of up to 17 mm are possible. The e-chains parts are easily openable and can be quickly filled with cables. This allows a straightforward installation and also allows maintenance or repair in case of damage. Cable retrofitting is possible in many cases, so that more cables can be changed or added to the system later. The e-chains can be quickly retracted up to their original position. Extension lengths from 4m to 14m are standard in the product range. In addition, it is possible to produce extension lengths of up to 50 m for special projects. The maximum extension and retraction speed is 1 m/s. Accelerations up to 2 m/s2 are possible. In the case of the lateral speed, a maximum value of 1 m/s applies and for lateral acceleration a maximum of 1 m/s2 (radial) or 0.25 m/s2 (axial). The e-spool was also intensively tested for its durability and service life at the igus test laboratory, the industry's largest testing facility with a floor area of 2,750 m2. 24,000 double strokes were completed at maximum rotational movement without any problems. Depending on the application and filling, the achievable service life is up to about one million strokes. After about 75,000 double strokes, the retraction spring must be replaced during maintenance. Optionally, you can equip the e-spool standard with one or two twisterbands. An e-spool with only one twisterband has a drum diameter of 600 mm and can weigh from 13.5 kg to 48 kg. If you want to carry more cables, it is advisable to use an e-spool with two twisterbands. This version has a drum diameter of 850 mm and a weight of 40 kg to a maximum of 55 kg. For heavy-duty applications, there is a special HD version of the e-spool standard, with an extra-strong spring. The retraction force can be increased again, especially for heavy, vertical applications, for example in acoustic and lighting installations. For the e-spool HD there is always a choice between one or two twisterbands. In general, all components of an e-spool are halogen-free and comply with the general fire protection standards for building technology and machines as well as those for building materials and components (DIN 4102 or DIN EN 13501). In addition to the standard options for the e-spool standard, the e-spool is also available in various special variants that can meet the individual needs of a stage application. The mini e-spool was developed for very small installation spaces. As the drum and shaft block are made of aluminium, it is extremely light (only 3.3 kg) and can be integrated anywhere. It is designed for extension lengths up to 2m and is ideal for small circular movements. If only one cable is required, the e-spool can also be used with manual extension. A detent mechanism reduces strain on the cable and prevents unwanted rewinding. Despite an extension length of 5m, the diameter of the spool is only 300 mm. However, the e-spool variant with the greatest relevance for stage technology is probably the e-spool power. This has a motorised retraction system. As a result, high fill weights and movements in all directions are possible. Instead of a retaining spring as in the standard e-spool, a motor retracts the spool. This overcomes the technical limitations of the standard systems. This is possible because the motor increases the power and allows a higher cable fill weight. This means more cables and larger diameters can be carried. At the same time, longer travels of up to 50 m and more are now possible. With a maximum extension and retraction speed of 1.2 m/s every additional metre is managed quickly. As the e-spool power does not require retraction springs, the maintenance intervals are further apart. There is no tensile strain on the cables. Therefore, the e-spool power ensures a longer service life for both itself and the cables. Since it is supplied with a drive and control system, it can be integrated quickly into the respective stage machinery.


Zig-zag: Unconventional solutions for unconventional theatres

Modular design and flexibility of the e-chains allow a creative solution for vertically hanging applications that is not only cost-effective, but also very space-saving and inconspicuous. If stages or heavy stage platforms have to be moved, lifting heights of many metres and heavy loads have to be managed. So far, systems that have been used are noisy, space-consuming and visually intrusive. With the "zig-zag" installation method using igus e-chains from Treotham, there is an effective alternative for this, which is characterised by its compact design. By using reverse bend radii, the e-chains can be stored in a zig-zag pattern. In this way only very little space is required. When the stage or platform is raised, the e-chain unfolds with low noise. This installation method is possible with all e-chains of the E4 series. The entire e-chain practically disappears as it is stored automatically in a standardised zig-zag box, and this can be integrated in the stage pit or fixed on movable lighting trusses. This box can optionally be chosen in matte black or another colour. The e-chains are available in external dimensions of 75 to 500 mm with box lengths of 600 to 3,000 mm and box heights of up to 2,000 mm. As standard, travels of up to 40 m can be implemented just as speeds of up to 0.4 m/s and accelerations of up to 1 m/s2. Even higher values are possible on customer request. The zig-zag principle has already proven itself in practice in a wide variety of applications. An example from the theatre technology field is again at Mountford Hall in Liverpool, where zig-zag e-chains are successfully in use in order to supply the lighting trusses with energy. At maximum height, the e-chains are fully retracted in their baskets directly above the respective crossbeam. If these are lowered, the e-chains unfold automatically. Everything is space-saving and as unobtrusive as possible for the audience. An all-round flexible system that, as a specific customer solution, could only be created through close cooperation in concept and execution. Roger Kirby, installations director at Adlib Audio, the company responsible for it, praised the good collaboration: "We were able to work closely with the igus engineers at all times.”


The slim alternative to zig-zag: The igus Liftband

The igus Liftband was designed for similar applications, but following a different approach than the zig-zag method. It was developed for vertical applications up to 13 m and with lower cable loads, although higher fill weights are still possible with the use of nylon bands. It moves very quietly and has a modular design that can be easily adapted to different heights. Energy, data and pneumatic cables can be moved together. In the process speed up to 1 m/s and acceleration up to 2 m/s² are possible. With a bend radius of the cables up to 250 mm, the space requirement of the Liftband is exceptionally low. The Liftband is therefore the perfect alternative to zig-zag solutions, if very little space is available. The chain is stored in a solid steel basket, so that the retracted system is barely visible. However, for both the zig-zag box and the Liftband it is necessary to configure every application individually. Therefore, a Treotham designer should be consulted in the project planning. Only a little time is needed from configuration to delivery - the simplest as a ready-to-install plug-and-play system with pre-assembled cables and connectors.


Versatile and robust cables for stage technology

With the zig-zag principle, not only can different e-chains be used, but all media cables (energy, data, hydraulics, pneumatics) are also guided in one system. In stage construction in particular, a variety of sensitive devices such as cameras and speakers are used. This requires a wide variety of cable types. Energy, data and signals must be transported just as reliably as, under certain circumstances, water or compressed air. With the chainflex product range, there is an assortment of 1,354 cable and hose types available from stock, from motor, control, servo, bus, data and encoder cables to modern fibre-optic cables, with cable lengths of one to several hundred metres. Chainflex cables have been specifically developed for moving use in energy chains and withstand very high mechanical stresses in moving applications, even with twisting movements. Designed for many cycles, high speeds and accelerations as well as long travels, they work reliably without failure over long periods of time. They therefore have a unique 36-month guarantee. In addition to these general advantages, certain chainflex cables have performance features that are particularly interesting for the stage technology. Examples of this are the extremely bend-resistant and flexible chainflex types, which can be safely used in confined spaces. Because of the "low bending" concept, which is available for all cable types, smallest bend radii are possible, even down to four times the cable diameter. Cables with TPE outer jacket are halogen-free and flame-retardant, thus meeting the required fire protection standards. Even more time can be saved with ready-to-connect cables from the readycable range or with completely pre-assembled e-chain systems, including matching plugs, from the readychain range.


Components for camera robots and guidance systems from Treotham

Igus "motion plastics", plastic components for moving applications, can be used in a variety of ways in stage technology. Whether in stage construction, light or audio technology, low-friction plastics are a cost-effective and easy alternative to conventional materials. They adapt to any space and any type, get along without any lubrication and reduce maintenance costs. An example of this are the energy supply systems of the E6 series, which are in use in the studio of ARD-aktuell (ARD current news), where, among other things, the Tagessschau (daily news) and the Tagesthemen (daily prime time news) are produced. The former independent specialist for studio technology, Camerarobot Systems GmbH, was looking for a reliable guidance system for its three camera robots, which guarantees not only long service life even at high loads, but also works very quietly. The E6 modular system, which can be ideally adjusted to the different travels, has chain links with a special design with abrasion-resistant connections, which ensure extremely low-noise and low-vibration operation. Additional noise-damping mats in the guide troughs ensure very high smoothness during tracking shots. Since the E6 can also be used laterally, there are completely new freedoms in terms of design and space requirements. Another compact and silent overall energy and data supply system ideal for camera systems is the micro flizz. The smallest e-chains can master even long travels in a guide channel. Virtually no noise is emitted since a plastic spring attenuates the rolling noise of the chain in the channel. With an acceleration of up to 50 m/s2, an operating speed of up to 6 m/s and data rates up to 10 Gbit/s, the micro flizz can execute fast tracking shots safely, and all of these in the smallest of spaces.