Sefuse® SF Series Design

The SEFUSE brand, SF-R series thermal links are designed for high current applications. The thermal sensitive pellet in the SEFFUSE brand TCO liquefies when the temperature rises to the melting point of the thermal element. This, in turn, allows a spring action to permanently break the electrical circuit.


SEFUSE SF-R Series Thermal Link Design

Unique to the SCHOTT SEFUSE design, is the increased reliability of the leads that are supported by an epoxy-seal- end ceramic pipe. Design features of the SEFUSE brand include:

  • Simple construction for trouble-free operation.
  • High Current carrying capabilities
  • Miniature sizes permit unparalleled design possibilities in extremely small spaces.
  • Many styles and configurations available for maximum design flexibility.
Animation of the Operation of the SEFUSE SF-R Series Thermal Fuse


Before Operation

The SF-type contains a sliding contact, springs and a thermal pellet inside a metal case. When spring B is compressed, there is firm contact between lead A and the sliding contact. At normal temperatures, current flows from lead A to the sliding contact and then through the metal case to lead B.


After Operation

When the ambient temperature rises to the operating temperature of the SF-type, heat is transferred through the metal case and melts the thermal pellet. Springs A and B then stretch and the sliding contact moves away from lead A, thereby opening the electrical circuit.