Online Stator End Winding Thermography using Infrared Sensor Array

Temperature monitoring is vital for protection and online health assessment of winding insulation of rotating electrical machines. The conventional method of embedding temperature sensors into the stator winding is reliable for localized measurements but could be blind to hot-spots depending on sensor proximity and fault severity. The more recent Infra-red (IR) camera based thermographic techniques are non-invasive and non-contact in obtaining machine's casing temperature distribution. However, they suffer from low sensitivity in detecting incipient winding faults. To overcome these limitations, a sensor array composed of discrete IR thermopile sensors mounted along the inner wall of the stator's casing is proposed in this paper. Although the system is invasive, it is non-intrusive and provides direct temperature distribution along the end-winding region in a non-contact way. The effectiveness of the sensor array in providing temperature distribution and inter-turn short circuit hot-spot detection is validated with experiments conducted using an induction motor.