Advanced startup transient model of a dual-cage induction motor for a broken rotor bar fault using a standstill test

Large induction motors used for traction applications that require loaded starts may have relatively complex dual-cage rotors. The outer cage typically withstands prolonged startup times and high starting currents, which increases the likelihood of fatigue failures, such as broken rotor bars (BRB). These failures result in high levels of stress in dual-cage induction motor (DCIM) drives. In this research, we aim to demonstrate the effect of the degree of damage on the characteristics of the DCIM during the starting phase. Before this, it is necessary to develop a higher-order model that enables us to better understand large transient operations. For this reason, a modern measuring device for the identification of electric machines, known as standstill frequency response testing (SSFR), is proposed here. The findings were verified experimentally using a 7.5 kW DCIM under various load and failure scenarios. The BRB model demonstrates that the proposed method is an effective tool for BRB modeling and diagnosis purposes.