The implementation of wide bandgap semiconductors, such as Silicone Carbide (SiC), in power electronic devices may intensify the electric stresses in motor drives, accelerating motor's winding insulation failure. Thus, the purpose of this work is to investigate the degradation of winding wires' enamel insulation subjected to high frequency and high dV/dt impulse voltage generated by a lab-designed SiC inverter. The twisted pair specimens have been tested under impulse voltage at 600÷1400 V peak voltage range. Specimens' temperatures, discharge currents and light emission spectrum are measured. The experimental results show that barrier discharges arising between wires' turns have filamentary structure. The discharge filaments and periodical traces of erosion on wires' turns have been observed by optical microscope. The electric field in twisted pair at 600÷1400 V voltage range has been simulated using the ANSYS Maxwell software. The damaged insulation areas correspond to the areas of high electric field between wires' turns. The rise in switching frequency up to 70 kHz increases the discharge repetition rate and energy of barrier discharges; enlarges discharges' filaments tracks. In presence of barrier discharges the temperature of tested specimen increases significantly, accelerating insulation destruction in discharges locations.