Search

With the increased demands regarding the reliability, availability, safety and affordability of key public infrastructures, it becomes increasingly challenging for asset owners and managers to achieve a proper balance amongst performance, risk and cost. As a response, operators of critical infrastructures need sound solutions to maximize the value of their assets, meanwhile realizing their business values and objectives. This requires well-defined decision-making processes with an adequate risk management concept embedded.

Condition based assessment of OLTCs has become more popular in recent years, and the importance of reliable and accurate diagnostic techniques is being realized. The work described in this paper aims to improve existing diagnostic techniques, develop new ones and combine some techniques (hybrid) in order to realize a highly reliable set of diagnostics for tap changers. Topics addressed in this paper include motor power measurement, dynamic resistance measurement and vibro-acoustic measurement, the latter designed and tested as part of this project. Preliminary results show that in particular a combination of aforementioned techniques may lead to improved condition assessment and may lead towards automated and online monitoring of tap changer operation.

This paper discusses a decision-support model for asset managers to prioritise assets requiring additional maintenance or replacement, by estimating asset remaining-lifetime and failure impact. The asset health and risk model (AHRM) being the heart of this model is based on dedicated asset-condition assessment functions in combination with usage-based condition estimations and a statistical approach using Monte Carlo simulations. This results in a health index colour code with two dimensions. The colour itself gives an indication of expected remnant life or additional maintenance requirements and the colour intensity gives an indication of the assessment reliability, thereby providing a clear and easily readable dashboard for the asset manager. A risk-based approach is used for further decision support. For each asset a risk-impact categorization is provided and plotted in a risk matrix, enabling risk prioritization on both probability and impact. The paper describes the methods behind the model.