Emulating bearing faults — A novel approach

Abstract

Abstract-The relation between evolving mechanical faults in rotating electrical machines and their reflection in the machines' electrical parameters still requires a lot of research. This implies serious obstructions in the evolution of e.g. Motor Current Signature Analysis as a complete and reliable condition monitoring technology. This paper presents the translation of common bearing faults into specific rotor-stator movements using finite element modeling. Subsequently, a novel method to elucidate the complex relation between rotor movements and the electrical parameters of an induction machine using an experimental test setup is described, dimensioned and simulated. Replacing one of the induction machine's bearings with an Active Magnetic Bearing will give the opportunity to create specific rotor movements and consequently evaluate different programmable mechanical faults and their reflection in the stator current and/or voltage with high relevance and reproducibility.

Single point outer race bearing fault severity estimation using stator current measurements

“…Regarding the horizontal force-function f x (t), the times t o , t p and t n remain exactly the same. Due to the change of direction of the gravitational force, the magnitudes I p,x and I n,x can now be written as, [13]:…”

“…These forces have a corresponding duration of acting defined by t n and t p . All these mentioned parameters are defined for α pit ∈ − π 2 ; π 2 as follows, [13]:…”

“…The most vital and challenging part in this approach is characterizing the movements between the rotor and stator during evolving faulty conditions. Those movements are analytically obtained and validated in [13] for single point bearing faults and are further analyzed and applied in this paper.…”

“…the stator current can be investigated thoroughly. Driven by this problem-statement, the authors created a novel method in order to emulate mechanical faults with high reproducibility and accuracy, [13]. Consequently, investigating the relations between mechanical fault-severity and the stator current fault signatures under different environmental influences becomes possible.…”

“…The obtained movements will serve as set-points for the AMB, of which the principle, dimensioning and implementation is briefly discussed in §III. Specific scientific details regarding §II and §III can be found in [13]. After completely constructing and implementing the whole AMB-system, extensive experiments are conducted.…”