Bussmann FRS-R-300 Fuse, Time Delay, Class RK5, FRS-R Series, 300 A

These 600VAC UL Class RK5 fuses are time delay and nonindicating. – They tolerate temporary inrush currents without opening, which prevents nuisance-blowing from motor and equipment startups. – Also called slow-blow Class RK5 fuses, these 200kA IR fuses open to disconnect an electrical circuit when exposed to sustained loads and short circuits. – They have no indicator for identifying a blown fuse, so they’re sometimes used with an indicating fuse block or cover. – UL Class RK5 fuses provide moderate current limitation for general use applications where more current-limiting RK1 fuses aren’t needed. – These fuses have an interrupting rating (IR) of 200kA and are the same size as Class H and K fuses, but have a rejection feature that prevents an accidental downgrade from a current-limiting system. – Their modified terminals ensure a match with the rejection clips in Class R fuse holders that prevent the installation of fuses with a lower interrupting capacity. – They’re typically used in newer equipment, but can also be used with a Class H fuse holder to upgrade older installations from Class H or K fuses for improved overcurrent protection. – They are current-limiting to prevent electrical damage by disconnecting circuits before they’re exposed to the full magnitude and duration of an overcurrent.