Pengaruh Kelembapan Relatif terhadap Hasil Uji Tahanan Isolasi Peralatan Outdoor Gardu Induk di Kawasan Gunung Salak

Substations play a crucial role not only as distribution points for delivering electrical energy from power plants to consumers but also as management centers of the electrical system that function to reroute power flows, thereby ensuring efficient and reliable energy delivery. One of the environmental factors that significantly affects substation equipment performance is humidity, which can directly trigger corrosion on metal-based components and indirectly reduce insulation performance, as indicated by results from periodic testing. This study aims to analyze the influence of ambient relative humidity on the insulation resistance test results of outdoor equipment at the 150 kV Gunung Salak Substation, covering the Current Transformer (CT), Capacitive Voltage Transformer (CVT), and Lightning Arrester (LA). The data used include biennial insulation resistance test results from 2017–2023 across four testing cycles, along with local humidity records, analyzed through correlation methods and risk assessment using Failure Mode and Effect Analysis (FMEA) with Risk Priority Number (RPN) calculations. The study site shows consistently high humidity levels, with an annual average of about 80–81% and a peak of 90.89% in July 2021, which has the potential to impact equipment insulation performance. The analysis reveals an inverse relationship between humidity and insulation resistance values: CT exhibits a strong negative correlation (r = −0.754), LA shows a significant negative correlation (r = −0.784), and CVT (r = −0.789) indicates a declining insulation resistance trend as humidity increases. Nevertheless, all test results still meet PLN’s minimum standard for 150 kV equipment (≥150 MΩ), with the lowest recorded value of 522 MΩ for LA in 2019 and the highest 251,000 MΩ for CT in 2023. Furthermore, the FMEA identified three failure modes in LA with the highest mitigation priorities, namely increased pedestal inductance at both terminal ends (RPN = 384), phase-to-ground short circuit during operation (RPN = 180), and hotspots on the body (RPN = 162), as well as the risk of internal flashover in CT (RPN = 135). These findings underscore the urgency of humidity control and the implementation of risk-based maintenance strategies to enhance the reliability of
outdoor equipment operating in high-humidity environments.
Keywords: Humidity, Insulation Resistance, Substation, Correlation Analysis, FMEA