The SFFR gate resistors in IGBT driver circuits from Caddock Electronics are now available up to 1100 V. The technology of the ultra-fast Sudden Fault Fuse Resistors (SFFR) eliminates the catastrophic damage in the gate driver circuit caused by the sudden breakdown of gate isolation in the IGTB. The SFFR technology differs from the conventional fuse which relies on the relatively slow pulling apart of a melted metal element. In the SFFR the sudden application of the high voltage fault instantaneously causes distributed multiple interruptions along the length of the SFFR element, quietly, opening the high voltage fault. The SFFR can be customised. The Gate resistor (Rgate) ranges from 1.0 to 30 Ohm. Sudden fault voltage across Rgate is caused by the gate isolation breakdown of an IGBT (fault mode). Examples of the fault voltage range capability are as follows: “range 1” between 200 and 500 Vmax DC; “range 2” between 400 and 1100 Vmax DC; „range 3“ between 600 and 1500 Vmax DC. The opening time is typically less than 20 sec. The gate resistor power features up to 1.0 Watt.