Stator Winding Fault Thermal Signature Monitoring and Analysis by In Situ FBG Sensors

Abstract

Winding short circuit faults are recognized as one of most frequent electric machine failure modes. Effective on-line diagnosis of these is vital, but remains a challenging task, in particular, at incipient fault stage. This paper reports a novel technique for on-line detection of incipient stator short circuit faults in random wound electrical machines based on in situ monitoring of windings thermal signature using electrically nonconductive and electromagnetic interference immune fiber-Bragg grating (FBG) temperature sensors. The presented method employs distributed thermal monitoring, based on the FBG multiplexing feature, in a variety of points within windings, in proximity to thermal hot spots of interest that arise from fault. The ability of the proposed method to enable fault diagnosis through identification of fault-induced localized thermal excitation is validated in steady-state and transient operating conditions on a purpose built inverter driven induction machine test facility. The results demonstrate the capability of unambiguous detection of inter-turn faults, including a single shorted turn. Furthermore, the winding thermal and electrical characteristics at the onset of inter-turn fault are examined and correlated, enabling better understanding of fault diagnostic requirements. Index Terms-Fiber-Bragg grating (FBG) sensor, insitu thermal monitoring, inter-turn fault detection, inverter driven induction motor.

Electric Machine Bearing Health Monitoring and Ball Fault Detection by Simultaneous Thermo-Mechanical Fibre Optic Sensing

“…Fibre optic sensing has emerged as a promising alternative for electric motor condition monitoring: its application for machine mechanical and thermal monitoring [5][6][7][8][9][10][11][12] is attracting increased interest. FBG sensing technology, with its advanced features such as small size, EMI immunity, multiplexing and multi-physical sensing presents an attractive proposition for enabling targeted in-situ monitoring of bearing multi physical operating conditions.…”

“…The FBG sensor cost is currently comparable to cost of sensors conventionally used in electric machine applications, but the required FBG interrogator systems are costly. FBG multiplexing and multiphysical sensing features are key in enabling sensing system cost reduction for advanced electric machine monitoring applications: multiplexing facilitates distributed embedded sensing schemes where a single fibre can carry an array of distributed sensing points, while multi-physical sensing can enable a comprehensive sensing system design where individual sensing points can monitor different physical measurands where required [7,10].…”

Integrated Fault Evaluation Through Fusion Algorithm Supported by Kalman Filter

“…It is well-known that FD techniques can be applied using various types of signals for electric machinery. For example, in papers [14][15][16][17], phase current [18], angular velocity or temperature [19]. Vibration signal is widely used for FD applications in electrical machinery.…”

Stator and rotor turn‐to‐turn fault detection in wound rotor induction machines based on the air‐gap magnetic field distortion

“…Temperature measurement by special embedded sensors is another technique to monitor the machine status from various viewpoints, as proposed in [52–54] for stator and in [55, 56] for rotor windings temperature tracking. In the presented method in [54], special thermal sensors such as Fibre Bragg grating (FBG) have been used to measure the stator winding temperature increase due to STTFs.…”

“…Temperature measurement by special embedded sensors is another technique to monitor the machine status from various viewpoints, as proposed in [52–54] for stator and in [55, 56] for rotor windings temperature tracking. In the presented method in [54], special thermal sensors such as Fibre Bragg grating (FBG) have been used to measure the stator winding temperature increase due to STTFs. As a brief comparison between invasive flux‐based and thermal‐based techniques, it can be noted that although thermal‐based techniques can measure the stator winding temperature at several winding locations and assess the machine health condition, they have some disadvantages in comparison with the flux‐based technique proposed in this paper as follows: Thermal‐based techniques inevitably lead to delays in the fault detection process as STTFs create an increase of the winding temperature, especially in the surroundings of the fault, but the existence of a non‐negligible thermal time constant means that if the sensors are installed far from the faulty point, they will take some time until they are able to sense the increased temperature. Motor overloading conditions or unbalanced voltage supply sources can lead to an increase and asymmetric distribution of the winding temperature, resulting in false tripping.…”