Alex Sandria Jaya Wardhana, Moh. Khairudin, Rustam Asnawi
Thermal overload protection is a fundamental function for ensuring the safety and reliability of electrical equipment under sustained overcurrent conditions. This study presents experimental validation and predictive modeling of the SEPAM 1000+ T20 thermal overload relay under cold and hot curve operating conditions defined by IEC 60255-149. A first-order thermal model was applied to determine alarm (ES1) and trip (ES2) thresholds, followed by laboratory testing to measure actual alarm and tripping times across multiple overload levels. The results showed strong agreement with theoretical predictions, with deviations consistently below 5%. A predictive model based on simple linear regression further confirmed this consistency, yielding a slope coefficient of 1.0039 and R2 exceeding 0.98. These findings validate that the SEPAM 1000+ T20 relay operates within IEC performance limits, while demonstrating the importance of considering both cold and hot curve characteristics when configuring protection systems. The proposed predictive model provides a reliable framework for optimizing relay settings, minimizing nuisance tripping, and improving the reliability of industrial thermal protection schemes. © 2025 The authors. This article is published by IIETA and is licensed under the CC BY 4.0 license (http://creativecommons.org/licenses/by/4.0/).
Department of Electrical Engineering Education, Faculty of Engineering, Universitas Negeri Yogyakarta, Yogyakarta, 55281, Indonesia; Faculty of Engineering, Universitas Negeri Yogyakarta, Yogyakarta, 55281, Indonesia
