New Cable Requirements for Large Wind Turbines

Wiring changes are looming for wind turbines.

The electrical systems on large wind turbines will soon be subject to a new standard, UL 6141, which could result in drastic changes to cabling practices. The standard applies to both new and refurbished wind turbines that generate more than 500 kilowatts of power. 

While UL 6141 has not yet been finalized, it proposes strict limits on the use of appliance-wiring material (AWM) within and between key generator subsystems.

The limits spring from a requirement that all accessible wiring must be either enclosed in a raceway or rated for tray cable usage. Since only UL listed cable offer the tray rating, AWM will no longer make the grade in many turbine wiring applications.

Here’s a breakdown of how the new standard will likely affect the different wind turbine subsystems:

Gearbox. There is no UL component standard specifically for gearboxes, so UL 6141 will apply to the wiring for gearbox components such as heaters and PT 100 temperature sensors.

Generators. The existing UL component standard for generators permits AWM cables under limited circumstances. To use AWM in generator wiring, there must be a ready-to-connect cable with connector. The generator must also be fitted with a grounding cable within the generator itself.  Since neither option is common with wind turbine generator manufacturers today, UL listed cable products will likely be the safest design strategy once UL 6141 comes to pass.

Tower. Since there is no UL component standard for the tower, UL 6141 applies. The proposed standard clearly calls for listed products for cables that run vertically up the tower—including those for power, control signals, lighting and hoists.

Drip Loop. Raceways are not commonly used in drip loops.  Assume that listed cable products will have to be used in this application.

To learn more about all the changes UL 6141 will bring, download our technical update.

Tips for Designing Cable Carriers

Of all the machine design details to worry about, cable carriers probably don’t top your list. Yet if you care about the reliability and uptime of moving machines, it pays to devote extra engineering attention to the carriers and the components within them.

A well-designed cable carrier will dramatically extend the life of cables and fluid power supply lines by protecting them from damaging bends, crimping, abrasive wear and crushing.

Unfortunately, some cable carriers are poorly-designed and can trigger the very same cable and supply line failures they were supposed to prevent, causing expensive machine downtime. The potential for failures can largely be avoided by following a collection of simple carrier design guidelines developed by our Systems Group.

Over the years, our engineers have designed, built and delivered thousands of populated cable carriers that have been implemented in a wide variety of servo and VFD applications on packaging, automotive and other industrial machines.

Here are some basic tips for designing populated carriers:

•         Calculate. Determine the minimum bend radius and clearances of all the components that will fill the carrier. Define the optimal carrier length and location of the fixed mounting points.

•         Weigh. Distribute the weight of the fill components within the carrier. Take the time to calculate the weights of individual components, and place the heaviest components on the outside of the carrier.

•         Influence. Consider the operating environment. Chemical exposures and thermal conditions can influence the design of cable carriers.

•         Divide. Split the carrier into separate cavities so the cables and hose can all move independently of one another.

•         Get Help. Involve your cable and carrier vendors in the design process. They work with carriers every day and can offer additional engineering expertise that will help you design a carrier that will go the distance.

For detailed engineering guidelines, download our technical paper on cable carrier design.