“Today the concept has changed and efforts are being directed to explore new approaches/techniques of monitoring.”
Residual life assessment (RLA) is a method that evaluates the type of degradation of equipment and determines its materials to ascertain the remaining life of the equipment.Residual Life extension (RLE) refers to identifying the scientific area describing the determination of technical health, prediction, and extension of the mean residual life for technical systems. The main objective of RLA and RLE includes studying areas related to determining the technical health of a critical technical system and predicting its mean residual life.
RLA & condition assessment process is conducted in a three-stage explained below with the example of a Power Transformer:
This stage reviews all engineering design and operational documents, past test data, and regular scans with Online test methods. New oil tests would be undertaken. This should identify the common problems and prioritise which offline tests are more critical in the second stage for detailed review activities, such as External inspection, IR/UHF surveys, oil tests for the main tank and LTC, including DGA and FURAN, and the checking of pump operation and fans.
Focusing on the risk identifications indicated in Stage 1, a range of outage tests are undertaken to investigate issues and correlate with the assessment from Stage 1.
This stage conducts Offline tests- PF/Cap, Winding and insulation resistance, SFRA, Turns Ratio, Leakage Reactance, Bushing, surge arrester testing, OLTC operation and dynamic contact resistance measurement, Moisture analysis of paper insulation by dielectric method (PDC+ FDS).
Residual life assessment determines the type of degradation of equipment and its materials to ascertain the remaining life of the equipment. It looks at various methods for test frequency and recommends necessary actions that are required to be taken to determine the remaining life of the equipment.
Residual Life Extension helps to extend the mean residual life of technical systems. The main objective includes determining the technical health of a degrading technical system and predicting its mean residual life. It is essential to conduct this study as it determines the working limit of a technical system or equipment, which is essential to ensure the equipment is not overworked.