Multifuse

Multifuse is a term used in electrical engineering to describe a family of protective devices that combines multiple fusing elements into a single package to protect circuits from overcurrent and overtemperature. These devices are used where reliable, compact protection is required, such as in power supplies, consumer electronics, automotive systems, and telecommunications equipment.

Design and formats: Multifuse devices come in axial-leaded, radial-leaded, and surface-mount formats. They may be standard one-element fuses or multi-element assemblies that provide redundant or staged protection for different parts of a circuit. Some variants integrate a polymer resettable fuse (PPTC) for post-fault reset capability, enabling protection without replacement. Ratings vary widely, from microamp to several tens of ampere current ratings, and voltage ratings from a few volts to hundreds of volts.

Operation and characteristics: Under normal current, the device conducts with low resistance. When current exceeds its rating, the fuse element heats and interrupts, isolating the protected portion. Multifuse assemblies may incorporate time-delay (slow-blow) characteristics to tolerate inrush currents, or fast-acting elements for rapid fault clearance. Temperature rating and interrupting capacity are specified to meet safety standards.

Applications: Multifuse devices are used in power adapters, battery packs, automotive electronics, telecom equipment, and other equipment requiring compact, reliable overcurrent protection.

See also: Fuses, Polyfuse, PPTC, Overcurrent protection.