Lightning caused overvoltages on power transformers recorded by on-line transient overvoltage monitoring system

Transient overvoltages generated by lightning strikes or switching operations represent a significant risk to bushings and windings of power transformers. They cause stress on the insulation system can, over time, dielectric failure damage Many transformer failures are reported as they not necessarily linked any particular event when occur but may be result prior from transient overvoltage events. Lightning waveforms appearing at terminals in real operating conditions significantly differ standard impulse voltage used during laboratory testing. The number amplitudes which depend various parameters such strike density considered area, since it determines how often is stressed overvoltages. Since usually unknown, an on-line recorder can with ability sample, analyse store transients real-time. In this paper, monitoring (TOMS) for transformers presented that capable continuously record real-time kinds Special attention paid caused recorded 150 MVA transformer. Recorded originating overhead lines correlated data location (LLS) supervisory control acquisition (SCADA) system. Collected about stresses basis assessment condition, estimation health index analysis events faults equipment failures.