ULW series wire-wound resistors overcome the problems associated with conventional flameproof resistors which can experience delays in fusing resulting in momentary loud flashovers. The UL-recognised ULW resistors, however, eliminate flashovers to fuse safely and silently, normally in a fraction of a second, and will not burn under any applied temperature or power overload condition.

Available in surface-mount or standard through-hole packages, resistance values range from 10 to 100Ω, with power ratings of 2W, 3W and 4W. ULW series resistors are designed to withstand inrush and surge conditions, operate in temperatures from -55 to +155°C and are classified to climatic category 55/200/56 according to IEC 68-1.