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Client Projects
Client Projects
Client Projects
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Condition, Criticality and Risk Assessment Model

Johannesburg, South Africa


The CCRA project at Eskom involved working with Eskom's asset managers to develop and refine Health Index formulations, along with a methodology and tools to justify replacement of aging equipment.

BIS staff also worked with Eskom to determine the preferred intervention for a gas insulated substation (GIS) in response to recent failures caused by a design flaw. The objectives were to improve the operational integrity of the GIS and reduce the risk of service interruptions in the future. BIS headed up a business case that evaluated four possible interventions and determined the preferred alternative from the perspective of the ratepayers. The main parts of the analysis are described below.


The analysis made use of a GIS tool that BIS had developed for Eskom. The tool projects the economic life of a GIS based on the risk profile of its composite bays. BIS estimated the overall rate of failure of GIS bays by analyzing failure data both system-wide and by compartment type. Consequence costs were determined for each bay based on what was expected to happen if a failure occurred. These consequences included impacts to customers based on service interruptions caused by failures for each bay.


For each alternative, BIS worked with Eskom to estimate the capital cost and benefits to future operational integrity. BIS calculated the replacement cost stream of each alternative and compared them based on their net present values. Lower net present values indicated more attractive options and the net benefits relative to the base case were calculated for each alternative. Finally, BIS performed sensitivity analysis around the results and determined that the benefit of the preferred alternative was stable with a benefit-cost ratio of over 16:1.

Date Completed: 2009

Health Indexing.
Risk Assessment.
Spending Prioritization.
Willy Majola
Director of Transmission
(011) 871-3226
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