Posted to News on 30th Apr 2013, 00:00
Hybrid cables open up options for automation
Hybrid cables which combine several functions within a single protective shield and insulating jacket can deliver real benefits in machine building and automation applications, says Jürgen Daut of Nexans.
>Traditionally, robots and other automation equipment have been powered and controlled using individual cables for the different power, control and data transmission elements. While this is a tried and tested formula, installation of multiple cable runs is both complex and time consuming, and leads to long cable lengths, with plants traditionally arranged in a 'star' configuration with cable runs to each machine from a central control cabinet and power source.
>When extending facilities, additional plugs and sockets may need to be retrofitted into the cabinet and using BUS-cables is one way of reducing cable work and offering easy connections. However, the recent introduction of state of the art hybrid cables is taking the concept of BUS-cables to the next logical level, which is to integrate multiple applications into a single cable, therefore reducing the complexity of installation and extension of automation systems.
>The use of a hybrid cable can enable an industrial plant to be configured in a more efficient daisy chain configuration, with one single cable loop powering and controlling machines. This removes the need for cables to run to each machine and back to the control and power cabinet, offering the promise of shorter and easier connections, freeing up options for expansion and offering capital savings. Typical savings for a hybrid cabling scheme are estimated in the order of 40% for an installation with a single machine, with the higher-value hybrid cable being offset by savings in cable length, connectors and labour costs.
>Made up of a power element to run motors, plus at least one other application within a single cable cross section, hybrid cables combine several functions, such as signal, bus, sensor, control and plastic optical fibre (POF) cables, all contained in a protective shield and insulating jacket, which can be specified to be chemically resistant to suit its operating environment. One example of a hybrid cable, albeit on a small scale is the humble USB cable used in computing, which delivers power and data to and from PCs and connected devices.
>There are literally hundreds of possible configurations: a fact which means that hybrid cables are not available as an off the shelf solution, but need to be tailor designed for each installation to fit with each customer's approach to control and automation. To date there are no standard designs, as customers' applications vary, but hybrid cables meet standards including: UL standards; VDE approvals; standards of BUS associations such as Profibus and sensor manufacturers; and the requirements of drive and control manufacturers.
>As a worldwide expert in the cable industry, Nexans, has supplied cable for more than 150 automation applications since it launched hybrid cables as part of its Motionline range in 2012. Reference projects include installations delivered for Siemens A&D - a leader in drive and controls - and DMG, the leading machine tool producer. Nexans has developed three classifications of hybrid cable, each recognising the escalating level of applications that hybrid cable is likely to experience in service, although hybrid cables tend not to put cable under the extreme acceleration or bending that some cables need to withstand routinely.
>Designed and manufactured at Nexans' Motion Application Centre (MAC) in Nuremberg, the cables are designed to deliver high performance and total reliability in a wide variety of control chain, bus, sensor and robotic automation applications. Nexans' research effort for the hybrid cable has lent on the firm's experience of its cables and its customers' applications, taking into consideration mechanical and chemical behaviour of materials, bending, torsion, trailing and simulation of real-world operation. Nexans research and development focuses its activities on the needs of cable customers and aims to ensure the firm's products continue to meet legislation and international quality standards, and is environmentally sustainable.
>Automation environment testing
>Although hybrid cable is a new product and the hundreds of possible configurations have not yet been manufactured and tested, typical hybrid cable configurations have been subject to torsion, bending, and acceleration testing to mimic the real-world automation environment. Typically carrying more power than traditional cables because it powers multiple machines in a loop configuration, a hybrid cable capable of carrying 28 amps on each 4mm2 power core has been developed and successfully tested.
>With sophisticated cable cross-sections and higher currents than those carried by conventional cable because they carry power to multiple machines, it's vital that cable connections are custom-designed to meet the requirements each application. As part of its total systems approach, Nexans has partnered with specialist cable connector companies (such as Intercontec) to develop connectors that can handle the designed configuration of cable elements, including power, signal, BUS and Ethernet. Enabling simple connection of the hybrid cable elements within a single connector means that connections are compact and ensures a high degree of protection up to IP 69K.
>So as automation customers look to the future, hybrid cable can offer financial savings and ease of installation for interconnection of automation equipment, as well as building in additional flexibility for future reconfiguration and expansion of facilities.
