SIOV Metal Oxide Varistors TDK EPCOS SIOV Metal Oxide Varistors feature a wide operating voltage range of 11 to 1100VRMS. These devices offer high surge current ratings up to 8kA and no derating up to 105°C ambient temperature. The SIOV leaded varistors meet new UL 1449 3rd Edition requirements. TDK EPCOS SIOV Metal Oxide Varistors applications include lighting, radio and TV equipment, and household appliances.