Sensor-Less Assessment of Terminal Contact Resistance Degradation Using RMS Voltage Dynamics in a Three-Phase System

This work presents a sensor-less voltage-based framework for assessing terminal contact resistance degradation in three-phase electrical systems. The proposed approach relies exclusively on RMS voltage dynamics without the use of additional sensors such as temperature or current probes. A controlled three-phase system is modeled in MATLAB/Simulink where terminal contact resistance is systematically varied under constant source voltage and load conditions. RMS voltage behavior is analyzed under healthy, pre-fault, and near-fault operating scenarios. Voltage recovery speed, voltage stability margin, and a Contact Resistance Severity Index (CRSI) are derived to quantify degradation severity. Simulation results demonstrate a monotonic reduction in RMS voltage magnitude, delayed voltage recovery, and reduced stability margins with increasing contact resistance. The proposed methodology provides a low-cost and non-intrusive solution for early detection of terminal degradation and is suitable for predictive maintenance applications in industrial power systems.