SEFUSE® SF Thermal Cutoff

Product Description

The SEFUSE® SF cutoff is a thermal link based on a one-shot operation principle and prevents electrical appliances from catching fire due to overheating. It uses an organic thermo-sensitive material inside a metal case and is able to operate in electric circuits with large currents.

SF type

The SF thermal fuse contains a sliding contact, two springs and a thermal pellet inside a metal case. Under normal temperatures, the sliding contact touches the top of the lead. The current flows through the sliding contact and the metal case to the other lead and the electrical circuit is closed. When the ambient temperature reaches a critical point, the thermal pellet melts and the springs move the sliding contact away, resulting in an interruption of the electrical flow.


The SEFUSE® SF thermal cutoff has the following advantages:
  • Remarkable sensitivity to temperature rise due to its shape and small size
  • High reliability and accuracy due to resin-seal
  • Appropriate for electric flows with large currents (6A-15A)
  • Environmentally-friendly product complying with the Directive on Waste Electrical and Electronic Equipment Directive (WEEE), and the Directive on the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment (RoHS)


It is used for a great variety of applications such as:
  • Home Appliances (e.g. irons, coffee makers, rice cookers, bread makers, toasters, refrigerators)
  • Comfort Conditioning Appliances (e.g. air conditioners, fans, humidifiers, heaters)
  • Personal Care Appliances (e.g. hair dryers, hair curlers, hair setters)
  • Business Appliances (e.g. copiers, laser printers, facsimiles, power strips)
  • Electrical Components (e.g. transformers, solenoids, AC adopters)
  • Automotive Electronics (e.g. electromagnetic clutches, resistors)

Technical Details


A thermo-sensitive material with a specific melting point is used as a thermal element in the SF type. Silver cuprate “AgCuO” has been used as the sliding contact material since April 2003 and replaced “AgCdO”, which was used prior to that time. Its patent is registered in many countries worldwide.

For additional information about this technology, please click on this link to our technology page.

Features/ Specifications

The SEFUSE® SF fuse uses an organic thermo-sensitive material as a thermal element. Therefore, the SFH type has the most stable material. The operating temperature ranges from 73°C to 240°C. All SF types except the SF/K version have a ceramic pipe in order to protect the sealing resin from stress caused by possible bending of the leads.
Series Electrical Ratings Rated Functioning 
Safety Standard
AC/DC Current Voltage
SF-K Series AC 6A 250V 73°C-216°C UL, cUL, VDE, BEAB, KTL, PSE
SF-R Series AC 10A/15A 250V 73°C-240°C UL, cUL, VDE,  CCC, KTL, PSE
SFH-R Series AC 10A/15A 250V 110°C-176°C UL, cUL, VDE, CCC, KTL, PSE
SF-Y Series AC 15A 250V 73°C-240°C PSE, (UL), CCC
Discontinued Products: Thermal Link SF(H)-E/F/L and SF-N/U Series

SCHOTT will discontinue the production of the SF (H)-E/F/L and SF-N/U series in December 2017. We have been mass-producing "SF-R series" which is the successor and new model since April 2013. For more information, please download the file below:

Please refer to "Cautions" in the Thermal Cutoff catalog for our design guidelines.

Forms of Supply and Product Packaging

Lead cutting and taping services are available upon request. For further information, please download the file 'Lead Cutting and Taping' below.

Standard forms of supply are available. Please contact our sales department if you have any special requests concerning supply and packaging.


For further information, please review our quality assurance page.
Trade Fairs & Events
Trade fair LED Japan, Tokyo, Japan, 29.01 - 31.01.2020
Trade fair SPIE PhotonicsWest, San Francisco, USA, 04.02 - 06.02.2020
Trade fair Medical Design & Manufacturing (MD&M) West, Anaheim, CA, USA, 11.02 - 13.02.2020
Trade fair OFC-Optical Networking and Communication Conference & Exhibition, San Diego, USA, 10.03 - 12.03.2020
Christoph-Dorner-Strasse 29
84028 Landshut
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