Electric and magnetic field measurements performed in the high-current la-boratory (HCL) revealed recurring disturbances in the form of damped oscillations. An analysis of the test procedures and a detailed investigation of the system configuration in-dicated that the likely cause of these disturbances was the asynchronous operation of con-tacts in a medium-voltage (MV) vacuum circuit breaker. This hypothesis was verified us-ing both field and circuit simulations. The non-uniform test circuit of the HCL was repre-sented as a cascaded equivalent model based on segmentation and distributed electrical parameters. The obtained simulation results confirmed the proposed hypothesis and high-lighted the significant impact of the switching process on the generation of electromagnet-ic disturbances in the MV supply path.