What do the letter designations on a fuse stand for?

The letter designations on a fuse typically indicate its specific characteristics, such as the type, speed, and application. For instance, "F" denotes a fast-acting fuse, while "S" refers to a slow-blow or time-delay fuse, which can tolerate temporary overloads. Other letters may denote specific standards or ratings. Understanding these designations helps ensure the correct fuse is used for protecting electrical circuits.