Bump testing for generators

Stator vibrations can loosen the end windings (winding heads) and cause them to vibrate. When the natural frequency of the end windings approaches twice the mains frequency, resonance will cause accelerated wear on the end windings. The natural frequencies of the end windings can be determined with the bump test.

Bump testing can be performed in one shift. Removal of the shields, blades, coolers and electrical safety, approved scaffolding, illumination and cleaning is the responsibility of the client.

Tests that are performed

Acceleration transducers are mounted temporarily on each tested bar-end to measure the radial, tangential, and axial directions. An impact hammer with an integrated force transducer excites the bar-ends. The FRF spectra show the normalized natural vibration response of the end-winding induced by the impact.

What type of generators and machines can be tested?

In principle, there are no limitations to the types of generators on which bump testing can be performed as long as conditions of accessibility and mounting of transducers are met. DEKRA developed the Bump Test software in-house and can customize the package to meet your specific needs.