A low-cost sensor for online detection of a transient abrupt drop in the drive speed of a three-phase synchronous generator

Foremost systems of electrical energy production are based on three-phases synchronous generators. In this work we are going to propose an efficient diagnosis technique, based on the use of a low-cost sensor, for the online detection of a transient abrupt drop in the drive speed system. Tests have been conducted on a four-pole brushless alternator driven by a DC shunt motor. Through conventional time-frequency analysis, four different techniques are suggested. Whereas the two first are based on the load currents analysis (one phase and three phases), the two other methods are based on the stray fluxes analysis (axial and transversal components). The experimental results have shown that, without the need of high-cost sensors (current probes), the investigated system failure can be effectively detected by means of simple search coil placed in a radial position near the alternator´s frame.