EMC Pulse Withstanding Resistors Welwyn / TT Electronics EMC Pulse Withstanding Resistors feature failsafe 240VAC fusing with good pulse handling capability. The flameproof (UL94-V0) metal film resistors are a small size for the 2W power rating. Welwyn / TT Electronics EMC Pulse Withstanding Resistors offer a resistance range of 4R7 - 68RΩ and are UL1412 recognized.