NEC SCHOTT - SM Type

The NEC SCHOTT SEFUSE™ SM type is a thermal cutoff designed to protect electrical home appliances and industrial electrical equipment from catching fire. It contains a fusible alloy inside an insulated case which interrupts the electrical circuit by melting when ambient temperatures reaches abnormal levels.

Product Description

The device is integrated into the electrical circuit of the appliance. Two leads are connected in the device by a fusible alloy, which is coated with a special flux. Under normal conditions, the current flows directly from one lead to the other through the fusible alloy. In case the ambient temperature should reach a critical point, the fusible alloy will melt and then condense into a drop around the end of each lead caused by surface tension and the special coating. As a result, the electric current is interrupted immediately.

Product Advantages

SM type thermal cutoffs:

Are stable and operate with precision to ensure maximum safety for the operation of electrical equipment
Can be mounted directly where temperature detection is required without insulation
Have fast thermal response due to their shape and small size
Have a resin-seal which ensures strong reliability and accuracy

Applications

The SM type is used in many different electrical products, such as in power supplies, motors, battery packs and automobiles.

Technology

The SM type is a one-shot operation device that uses a fusible alloy as thermal element inside an insulated ceramic case. The alloy is coated with a special flux.

For additional information about this technology, please click on the thermal cutoff technology page.

Features/ Specifications

All versions of the SM type use a fusible alloy as a thermal element and cover a range of operating temperatures from 76°C to 187°C. Some types are especially environmentally-friendly, 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).

Series	Electrical Ratings			Opening Temperature	Standard
Series	AC/DC	Current	Voltage	Opening Temperature	Standard
SM/G Series	AC	0.5A	250V	100°C-151°C	UL, CSA, VDE, BEAB, CCC, KTL, PSE
SM/B Series	AC	1A	250V	87°C-151°C	UL, CSA, VDE, BEAB, CCC, KTL, PSE
SM/A Series	AC	2A	250V	76°C~187°C	UL, CSA, VDE, BEAB, CCC, KTL, PSE
SM/G Series	DC	3A-5A	50V	100°C~151°C	UL, VDE
SM/B Series	DC	3A-6A	50V	87°C~151°C	UL, VDE
SM/A Series	DC	3A-7A	50V	76°C~187°C	UL, VDE

Please refer to this download for our design guidelines.

Forms of Supply and Product Packaging

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

Quality Assurance

The SM type is a reliable thermal protection device manufactured in a location certified by the International Standards Organization (ISO9001/14001 quality standard).

All SM type thermal cutoffs undergo an automatic internal resistance check, in addition to the standard quality assurance processes of NEC SCHOTT to ensure the consistent high quality of the product.

For further information, please review our quality assurance page. The Thermal Cutoff catalogs are also available from our download page.

sm_cautions.pdf