UBZ-304 Universal Electric Motor Protection Device. The UBZ-304 Universal Electric Motor Protection Device is designed for protection of asynchronous electric motors having power of 2.5 to 315 kW, with the use of external standard current transformers having output current of 5 amperes.The UBZ-304 Universal Electric Motor Protection Device is designed for protection of asynchronous electric motors having power of 2.5 to 315 kW, with the use ..