PROTECTION AND MONITORING SYSTEM FOR AN INDUCTION MOTOR WITH EMERGENCY SHUTDOWN FUNCTION

Abstract

The article addresses the issues of improving the reliability, energy efficiency, and resource conservation in the operation of three-phase squirrel-cage induction motors through the development and implementation of an integrated protection and monitoring system with an emergency shutdown function. The relevance of the topic is driven by the high failure rate of electric motors in the industrial sector, particularly in the agro-industrial complex, where up to 25 % of the motor fleet fails annually, mostly under partial load conditions (40–60 % of nominal).A concept for the design of an automated system is proposed, based on continuous monitoring of key operational parameters: phase currents, stator winding temperature, and rotor speed. The system not only detects critical deviations in motor operation but can also initiate emergency shutdown and transmit data to a higher-level SCADA control system.At the core of the diagnostic model are two informative indicators: the active power loss coefficient (kпе), which reflects energy consumption under non-nominal operating conditions, and the insulation resource consumption coefficient (kвр), which accounts for thermal aging of the motor’s insulation system.The study involved modeling different load profiles and analyzing the influence of ambient temperature on the insulation resource of an induction motor type 4A100S2U3. It was shown that increasing the ambient temperature from 20 °C to 40 °C, while maintaining the same load, leads to an increase in the insulation resource consumption coefficient from 0.19 to 0.7. This indicates a significant acceleration of thermal aging processes and highlights the importance of temperature monitoring during operation.The results confirm the feasibility of implementing a monitoring system that enables real-time assessment of the motor’s technical condition, prediction of the remaining insulation life, and timely decision-making regarding maintenance or shutdown. The proposed approach helps reduce failure rates, improve energy efficiency in industrial processes, and ensure the sustainable operation of electric drive systems.