Timely and accurate detection of the rotor winding inter‐turn short‐circuit fault of a synchronous generator can reduce the more serious damages caused by fault deterioration and economic losses, so developing online detection methods with high sensitivity is necessary. On the basis of the structural characteristics of the synchronous generator, this study proposes a sensorless online detection method for rotor winding inter‐turn short‐circuit faults, respectively, taking a 300 MW turbo generator and a 550 MW hydro‐generator as the objects of finite‐element simulation. The results show that the new fault diagnosis method of the rotor winding inter‐turn short circuit for the sensorless synchronous generator has high sensitivity and can realise real‐time monitoring of the faults.

No abstract

No abstract

No abstract

No abstract

Broken rotor bar (BRB) fault may cause deterioration of motor performance and interfere with normal production. Accurate detection of BRB fault is helpful in arranging overhaul and replacing equipment in advance. According to the theory of magnetic potential balance, the variation rule of the air-gap flux density of the squirrel-cage induction motor (IM) before and after the BRB fault is deduced in this paper. A large-size measuring coil is embedded inside one stator slot wedge, and BRB fault is diagnosed by combining the time-domain and frequency-domain characteristics of the induced voltage of the measuring coil. In the stage of validity verification, a 200 kW and a 7.5 kW squirrel-cage IM are selected to complete the finite element simulation and fault-simulation experiments, respectively. Compared with the traditional motor current signal analysis method, the detection performance of BRB fault under different load levels is verified, which provides a new solution for the fault diagnosis of BRB fault of the squirrel-cage IM.

In this article, the qualitative theoretical derivation, together with finite element analysis and experimental studies are presented to investigate the unbalanced magnetic pull (UMP) as well as the rotor vibration characteristics. Differently from previous studies, this study focuses on the UMP/vibration not only under the normal and the conventional radial rotor eccentricity conditions but also for three-dimensional (3D) hybrid static air-gap eccentricity (SAGE) cases which are composed of both the radial SAGE and the axial SAGE. The detailed UMP expressions before and after each SAGE, are first deduced based on the analysis of the magnetic flux density variation. Then, the 3D finite element calculation and the experimental study are carried out on the CS-5 prototype generator which has two poles and a rated speed of 3000 rpm in order to validate the proposed theoretical analysis. It is shown that the DC component and the even harmonics of the radial UMP/vibration, especially the second harmonic, increase under the SAGE conditions. Specifically, the increment of the radial SAGE increases both the radial and the axial UMPs/vibrations, while the growth of the axial SAGE increases the axial UMP/vibration but meanwhile reduces the radial UMP/vibration.

No abstract