Wind Turbine Generator Testing: Frequently Asked Questions

If you’ve been blindsided by electrical and insulation related failures of generators, Electrom is here to answer your questions.

O&M operators have questions about generator testing for predictive maintenance programs.  Low voltage and low quality testers don’t give you all the data you need to make intelligent maintenance decisions.

Generator Testing FAQ

A: High voltage generator testing, including surge testing and partial discharge measurements, gives your operation the ability to:

  • Troubleshoot and diagnose electrical problems up-tower.  In some cases, repairs can be made, therefore deferring or eliminating the need to extract the generator.
  • Find existing problems now and spot potential problems sooner.
  • Prioritize generators for maintenance and repair.

A: Many generator professionals, including:

  • Wind generator manufacturers
  • Motor and generator repair shops
  • Predictive and preventive maintenance professionals
  • Wind farm owners and operators

A: Unplanned downtime is costly! Winding failures can happen at any time, causing a halt to operations. Testing generators and motors regularly can prevent unscheduled downtime and associated costs such as:

  • Lost energy generation and revenue
  • Cost of repair or replacement of assets
  • Cost to hire a crane or lift equipment
  • Loss of credibility and damage to reputation
  • Personnel costs to restore operation quickly

A: Failure modes in rotating equipment can be attributed to bearing and mechanical issues as well as electrical issues with the rotor and stator. Some common electrical issues that can be diagnosed using the iTIG are:

  • Weak or shorted winding insulation turn-to-turn, phase-to-phase and to ground
  • Resistive connections
  • Wye ring problems
  • Winding contamination levels
  • Partial discharge
  • Dielectric breakdown in surge arresters

A: Yes. Synchronous or asynchronous, wound or permanent magnet rotors, all generators can be tested by the iTIG.  690 V generators are common but generators can range up to 12,000 V.  Test voltages of 2 times the operating voltage plus 1000 V is a common recommendation.  The iTIG test instrument can be specified to use a maximum test voltage that is sufficient for your needs. For higher voltage generators, the Electrom Power Pack is practical to use in the confines of the nacelle because of its small size.

A: Yes. We offer free online training. Training onsite or at our facility in Colorado is also available.  Free technical and application support for the life of the tester comes with the purchase of the tester.

Learning to use the tester is easy. The iTIG can be set up to perform the same test in the same way every time so testing up-tower is efficient and consistent. Either Electrom or the operator can do the setup.

A: Surge and PD testing benefits an O&M regardless of warranty related issues. High voltage testing including surge and partial discharge testing gives owners and operators visibility into the serviceable lifetimes of its assets so that maintenance can be scheduled and appropriate action can be taken before a failure results in costly unplanned downtime.

A: Yes, the iTIG can be used to test surge arresters. Megohm tests, also known as a insulation resistance (IR) tests, are the type of test normally used for surge arresters.  Six IR tests can be done quickly and easily by pre-loading generator and surge arrester data into the tester.  Test results are automatically entered in the Test Summaries File for trend analysis and comparison of results to groups of generators.

A: Yes. Ancillary component tests can be performed using the iTIG.  Auxiliary motors such as those used in cooling systems, automated lubrication devices, nacelle yaw motors, and pitch motors can be tested using the same basic procedures as the turbine generator. Test voltages should be adjusted based on the operating voltage of the test load.