Windpower Engineering & Development

  • Home
  • Articles
    • Most recent posts
    • News
    • Featured
  • Resources
    • Digital issues
    • Podcasts
    • Suppliers
    • Webinars
    • Events
  • Videos
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
  • Magazine
  • Advertise
  • Subscribe

How can you prevent encoder failure in wind turbines?

By Nic Sharpley | May 26, 2015

Photo: Nidec Avtron Automation Corporation

Photo: Nidec Avtron Automation Corporation

Encoders are a forgotten component in wind turbines—at least until they fail.

Wind turbines are a challenging application for encoders, something many OEMs and end-users discover just after installation. The constant vibration and thrust is tough on tiny encoder bearings (and for absolute encoders it’s tough on internal gearboxes).

Another problem is temperature cycling combined with moisture. Encoders typically come from the factory sealed against air exchange. But as the temperature of the encoder and the outside air cycle up and down out of step, the constant pressure on the seals, especially the rotating seal on the shaft, causes them to fail. When the seals degrade the encoder’s optics and bearings are exposed to moisture, dirt, and oil leading to a maddening set of intermittent failures due to internal condensation.

Now customers are moving toward magnetic encoders instead of optical units on everything from blade pitch to generator control. Magnetic encoders have a huge advantage over optical because dust, dirt, water and oil don’t cause a magnetic sensor system to malfunction. Magnetic fields reach through all these materials just as they reach through air.

Even magnetic-sensor-based absolute encoders are available. These eliminate batteries, capacitors and internal gearboxes associated with tracking the number of encoder turns. This greatly improves an absolute encoder’s reliability.

Some magnetic encoder units had or still have a big vulnerability: magnetic fields from DC brakes used to hold the blade pitch position blind or confuse the encoder. In response, some encoder vendors offer shielded models and improved sensors that eliminate magnetic interference.

As many end-users replace failing OEM encoders they often upgrade the encoder bearings or eliminate them. Typical encoder bearings are tiny 20N units and in many small-shafted encoders a single bearing is used. The load and thrust caused by an imperfect coupling or engagement gear quickly overloads the bearings. Moreover, constant vibration causes fretting of the bearing races. So vendors have launched lines of encoders that are mechanically and electrically interchangeable and offer much larger bearings with 10 times or 20 times the existing bearing ratings.

An ever-larger share of wind turbine encoder applications uses no-bearing modular encoder designs. These magnetic encoders are used on the back of the generator or for the blade-pitch motor application. With wider-sensor-gap technology the customer can easily mount these units. With no bearings to wear out and magnetic sensor technology potted safely in solid housings these encoders are maintenance-free. No bearing modular encoders have accumulated a tremendous reputation for reliability in wind turbine applications.

Perhaps the most important trend is in encoder diagnostics. Encoder vendors are now providing “go-no-go” simple LED and remote diagnostics to greatly simplify troubleshooting. These have an immediate, proven effect: They eliminate 50% of the encoder replacements. How? Simply put, 50% of encoders with no diagnostics returned to encoder vendors had been proven to have no fault at all. The user or OEM customer replaced them but didn’t solve the real problem. Later they found the real problem but because the encoder was swapped out during troubleshooting it was suspect. That changes with a modern encoder. The diagnostic LED and feedback to the control system lets users know that the encoder is working and to look elsewhere for the problem.

These huge reliability improvements allow the encoder to go back to “forgotten” (trouble-free) devices in wind turbines.

By: Brian W. Winter, Product Manager at Nidec Avtron Automation Corporation


Filed Under: Encoders, News
Tagged With: nidecavtron
 

Comments

  1. Baba says

    March 17, 2020 at 3:43 am

    Hello. I work on turbines in Azerbaijan. We recently encountered a problem with the error 5221 Encoder synchronism error. Could you help us with tips on what and where to look

Related Articles Read More >

US government allows Empire Wind offshore project to resume construction
Richardson Electronics to deliver pitch energy modules to TransAlta wind fleets
Equinor halts work on Empire Wind offshore project after federal government order
ARESCA wants input on offshore wind standards

Podcasts

Wind Spotlight: Looking back at a year of Thrive with ZF Wind Power
See More >

Windpower Engineering & Development Digital Edition

Digital Edition

Browse the most current issue of Windpower Engineering & Development and back issues in an easy to use high quality format. Clip, share and download with the leading wind power engineering magazine today.

Windpower Engineering & Development
  • Wind Articles
  • Solar Power World
  • Subscribe to Windpower Engineering
  • About Us/Contact Us

Copyright © 2025 WTWH Media LLC. All Rights Reserved. The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of WTWH Media
Privacy Policy | Advertising

Search Windpower Engineering & Development

  • Home
  • Articles
    • Most recent posts
    • News
    • Featured
  • Resources
    • Digital issues
    • Podcasts
    • Suppliers
    • Webinars
    • Events
  • Videos
  • 2025 Leadership
    • 2024 Winners
    • 2023 Winners
    • 2022 Winners
  • Magazine
  • Advertise
  • Subscribe