Application of dissolved gas analysis in maintenance ranking of faulty oil-filled electrical equipment based on type and energy of the fault

摘要

Oil-filled electrical equipment are critical facilities for stable and reliable operation of a power system. Thus, their timely maintenance based on incipient faults identified and or ageing status is crucial in attaining this goal. Once faults presence has been established, subsequent maintenance scheduling is of paramount importance. A utility with many faulty oil-filled electrical equipment needs a logical way of ranking them for maintenance. This work applies dissolved gas analysis (DGA) of known faults and uses analytic hierarchy process (AHP) to evaluate the rank of each fault type. In addition, the breakdown of an assumed n-octane (C8H18) paraffinic hydrocarbon molecule, a key component of the mineral oil used in electrical equipment is used to estimate the fault energy involved during the process. Based on these, equipment are ranked accordingly for maintenance resource optimization. Faults are classified into five categories based on IEC 60599 standard. One hundred and seventeen fault cases of visually inspected equipment and documented in IEC TC 10 databases are used in the analysis. Use of fault type and total energy released during faults in maintenance ranking of faulty equipment shows a logical criterion with a great potential of practical application.