The L15S series is a traditional North American Bolted style high-speed fuse for protection of power semiconductor devices that are rated up to 150 V ac and up to 150 V dc Littelfuse POWR-SPEED products offer optimized circuit protection at the extremely fast speed required to protect power semiconductor devices such as silicon controlled rectifiers (SCRs), diodes, thyristors, triacs, transistors, and similar solid-state devices. These devices are used in power equipment including variable speed drives, power rectifiers, UPS systems, dc power supplies, and in a wide range of electronic equipment. May be used wherever extremely fastacting, current-limiting fuses with no time delay are required.