Thursday, 25 June 2015

New Cable Standards for Wind Turbines

Wind Turbines
There have been some changes to the wiring of wind turbines over the last year, as electrical systems on large wind turbines are now subject to a new standard. This standard is the UL 6141 which could see some drastic changes to cabling practices.

Both new and refurbished wind turbines that generate more than 500 kilowatts have to follow these standards. This new standard also proposes strict limits on the use of appliance-wiring material (AWM) within and between key generator subsystems.

These limits come from a requirement that all accessible wiring must either be enclosed in a raceway, or rated for tray cable usage. The new standards could affect different wind turbine subsystems, and here are a few example of how:

The Gearbox – There is no UL component standard specifically for gearboxes, therefore the UL 6141 will apply to the wiring for these components which relates to heaters and PT 100 temperature sensors as an example.

Generators – The existing UL component standard for generators permits AWM cables under limited circumstances. In order to use AWM in generator wiring, a ready-to-connect cable with connector must be set in place. This should also be fitted with a grounding cable within the generator itself. Since neither of these options is common with wind turbine generator manufacturers in today’s industry, UL listed cable products will likely be the safest design strategy now UL 6141 has arrived.

Tower – UL 6141 applies to towers as there is no existing UL for these. This clearly calls for listed products for cables that run vertically up the tower, including those for power, control signals, lighting and hoists.

While UL 6141 won’t necessarily outlaw AWM in wind turbine subsystems, a preference for listed cable products comes through loud and clear in the new standard. It remains to be seen whether electrical inspectors will accept AWM cable when it is known that the intent of the UL 6141 would be the use of listed cable products.

Design engineers working on new turbine projects may want to keep this preference for products in mind. Using listed products only will not only result in more durable wiring but will also ensure compliance when UL 6141 goes into effect.


No comments:

Post a Comment