Method of inspecting a generator air-gap

Abstract

The invention describes a method of inspecting an air-gap (1) of an electrical machine (2), which method comprises the steps of directing at least one laser beam (L) into the air-gap (1); detecting the laser beam (L) after reflection; determining the distance (d OK , d F ) travelled by the laser beam (L); and analysing the travelled distance (d OK , d F ) to detect an irregularity (F pole , F oval , F object ) in the air-gap (1). The invention further describes an air-gap inspection apparatus (3) for detecting an irregularity in the air-gap (1) of an electrical machine (2), which apparatus (3) comprises a laser module (30) realised to direct at least one laser beam (L) into the air-gap (1) and to detect the laser beam (L) after reflection; a computation unit (31) realised to determine the distance (d OK , d F ) travelled by the laser beam (L); and an analysis unit (32) realised to analyse the travelled distance (d OK , d F ) to detect an irregularity in the air-gap (1).

Description

technical field [0001] The present invention describes a method of inspecting the air gap of a generator and an air gap inspection device for detecting irregularities in the air gap of a generator. Background technique [0002] An electric motor or generator includes a rotor and a stator, with the rotor separated from the stator by an air gap. The air gap between the rotor and the stator plays a very important role in the efficient operation of the machine. In general, especially in the case of large electrical machines such as wind turbine generators, the rotor is realized as a field and carries an arrangement of magnets, while the stator is realized as an armature and carries an arrangement of stator windings. [0003] In the case of very large electrical machines such as direct drive generators, the outer rotor may have a diameter in the range of a few meters. Such generators have a correspondingly large number of stator teeth and poles. For example, in the case of a 3...

AI Technical Summary

Problems solved by technology

However, due to the depth of the generator, visual inspection of the air gap is extremely difficult and error-prone

An undetected misalignment of just one pole can have a significant negative impact on the air gap

Similarly, undetected misalignment of stator segments can result in non-uniform air gaps over segments of the generator

This imbalance can cause uneven torque (torque fluctuations)

In the worst case, irregularities in the air gap can lead to catastrophic collisions between the rotor and stator when the generator is put into operation

Such collisions involve very high costs, especially in the case of offshore wind turbines

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