All four European electric systems can be used by the ES 64 U4. Its electric components are mostly identical to those of ES 64 F4. The four-system series (with the 1500 V capability disabled within the software) are currently used in Austria by ÖBB and the private operator Rail Traction Service as Class 1216, in Slovenia by Slovenske železnice (SŽ) as Class 541 and in Poland by PKP Intercity (PKP IC) as Class EU44 "Husarz". In Italy RFI assigns it the classification E 190. Taurus locomotives have become notable for the musical-sounding notes, said to resemble an alto saxophone, produced when a train is moving off. The sound comes from the traction converters (German: "Stromrichter").