PLN has put as many as 115 gas-insulated substations into operation since 1980' s. In general the installed GIS work properly ever since it was energized. However, few sustain problems occurs at some substations. Several precautions have been done to solve the problems which ended with unsuccessful result. Despite of their anomaly condition, those GIS are still able to fulfill their main task, i.e.: transfer electrical energy. In order to avoid undesirable failure in the future, a comprehensive evaluation from technical and non-technical viewpoint should be done. This paper will start the discussion with statistical data of gas insulated substation population; sustain problems, speculative explanation of possible aspects, including the tropical circumstances, affects the performance of gas-insulated substation, and ended with solving problem proposal. As the boundary, the data and experiences are coming from Jakarta and Banten region (west part of Java Island) and discussion will not go to deep with technical aspects. In addition, non-technical aspect will also put into consideration. In the end of discussion, some feasible and appropriate actions to improve the gas insulated performance can be obtained.@en

In late 2004 PLN P3B decided to apply a new strategy of maintenance, condition-based maintenance, to her high voltage assets. Before implementation, several preparation steps consisting of several aspects should be completed. In PLN case, besides lack or incomplete data, the aspects influencing assets performance should be reconsidered. In general there are three main reasons that make the PLN system quite unusual. First reason is that PLN organizes and operates high voltage assets under tropical environment, some even combined with presence of high pollutant. Secondly, the electrical system is heterogeneous. Finally, the Java Bali power system uses three different grounding schemes. Majority gas insulated substations are designed to be able to operate under non-tropical circumstances and operated under reliable power system. In PLN the situation is completely different. Facts showed that in many occasions the capability of that equipment is unable to withstand possible disturbances appearing in PLN system. Hence a careful study should be done with the aim of understanding the influence of tropical, tropical-high polluted environment, heterogeneous power system, and grounding system to high voltage equipment. As not enough references of these situations exist, a combination of methods consisting of fuzzy logic and neural network will be proposed in developing a statistical model to assess the condition of equipment. The paper will discuss major aspects that influence the PLN high voltage assets performance and how significant is the influence of those aspects in the condition-assessment procedure.@en