Pruftechnik Service & Diagnosis Center is expanding its service spectrum to include the field balancing of rotor blades. The service will be performed using a mobile Vibxpert analyzer with a balancing program that has been adapted to the low rotating speeds of wind turbines.
The sensor system comprises a speed sensor and a highly sensitive accelerometer that produces measurement results at speeds as low as 0.1 Hz. The field test took place on a wind turbine damaged by lightening. One rotor blade suffered a five m crack and, because no replacement blades were available, was repaired. The repair led to an imbalance that was to be corrected by means of field balancing. It took only four balancing runs to balance the wind turbine. The tower’s natural frequency was not excited even when running at the resonance speed. The measurements themselves took about five to ten minutes each.
