Automation cables take the heat in fast-moving applicationsOpinion
Posted by: electime 29th January 2021
Andreas Rietz, Nexans Global Product Manager Automation, outlines why higher operating temperatures up to 90°C have driven the development of a new generation of automation cables for industrial installations.
Fast moving automation installations such as drag-chains, machine tools and robotics present a particular challenge for cables. They must ensure reliable transmission of data and control signals and/or secure power supplies while subjected to extreme dynamic loadings. At the same time, these cables have to withstand harsh manufacturing environments as well as complying with international standards and delivering safe, reliable and cost-effective performance.
To address these challenges, Nexans has focused on testing and R&D activities that enable cables to be exposed to dynamic operating loads that simulate realistic, in-service, conditions. This ensures that they offer the ideal combination of bending, tension and torsional strength required for their intended application. This research has also focused on ensuring that the conductor and insulation materials provide the fire and heat resistance demanded for safety and performance, as well as offering the resistance to attack by oils and other chemicals essential for a long service life.
The result of these intensive R&D efforts is the well-established MOTIONLINE range of automation cables that covers everything from miniaturized control cables to state-of-the-art industrial Profinet cables to bring the office and the production floor closer together. But while these standard cables, rated for 80°C, have served the automation industry well, new generation applications require a higher temperature rating to provide a wider safety margin. Otherwise, there is an increased risk of breakdowns that can result in costly losses in productivity.
The heat load factors in modern factories
The need for a higher temperature rating results from a number of factors that occur in modern factories. First, there is the trend to replace metal connectors with smaller, over-molded plastic connectors that have poorer heat transmission. Second, connectors and cables are being installed closer together, increasing the amount of heat generated within an often-confined space. Furthermore, the increased, fast-changing frequency and voltage in the cables puts the insulation material under a continuous high stress.
There was therefore a clear need to develop an automation cable that could withstand continuous operation at 90°C without increasing its dimensions or impacting its mechanical properties and especially dynamic performance – the capability to survive millions of bending cycles at high acceleration rates without failure. Following an extensive R&D and testing program, the answer was found by using an improved polyolefin-based insulation compound
The new insulation compound has been used to create the new generation of MOTIONLINE Servo Motor Premium 90° cables available with or without a signal pair, with cross sections up to 50 mm². They are capable of continuous long-term operation at voltages up to 1,000 V and temperatures up to 90°C, while offering the same dynamic performance and dimensions as standard cables.
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