termofusibles

Termofusibles, or thermal fuses, are temperature-sensitive electrical protection devices designed to open a circuit when the device temperature exceeds a specified trip point. They provide overheat protection for electrical appliances and equipment. Unlike resettable devices, thermofuses are intended for a single use; once activated they must be replaced.

Construction and operation: A termofusible consists of two conductors connected by a fusible element inside a heat-resistant housing. At the trip temperature, the element melts or a small pellet releases, breaking the circuit. The opening is irreversible, so the protection is permanent until the device is replaced.

Ratings and selection: The most important specification is the trip temperature, with common values around 72°C, 90°C, or 125°C, among others. Some designs also specify current rating and physical size. Performance depends on ambient temperature and placement; derating may be required near hot components.

Applications: Termofusibles are used in power supplies, printers, coffee makers, hair dryers, motors, transformers, and battery packs, as secondary protection against overheating and fire hazards. They are often located near heat sources and in series with the circuit they protect.

Maintenance and standards: Thermofuses are single-use devices; replacement is required after tripping. They are chosen to match the host device’s maximum operating temperature and environment. They are commonly listed as UL/CSA/IEC components and installed according to manufacturer guidelines.