Thermal Cutoffs (Thermal Fuses)
A thermal fuse (thermal fuse) is a device used to protect components when the temperature is too high. When the rated operating temperature of the thermal fuse is exceeded, the device will disconnect from the circuit, thereby cutting off the current and preventing fire or equipment damage.
1. Thermal Cutoffs (Thermal Fuses) Overview
Definition: TCO is an irreversible thermal protection device composed of a low-melting-point alloy, a special resin, and a shell (plastic or ceramic), which responds to temperature abnormalities through a fuse mechanism.
Working Principle: At normal temperature, the alloy connects the two pins; when the temperature reaches the preset threshold, the alloy melts and cuts off the circuit.
2. What are the Types of Thermal Cutoffs (Thermal Fuses)?
1) Structural Classification:
Alloy Type: divided into axial type (such as 2BN series) and radial type, with a temperature coverage of 65℃-216℃ and a current of 1-15A.
Organic Type: halogen-containing or halogen-free design, some models support spot welding (such as MP series), and the thickness can be less than 0.8mm.
2) Package Form: Ceramic or plastic shell, some models with insulated pins or preformed pins.
3. How to Select Thermal Cutoffs (Thermal Fuses)?
Temperature Parameters:
Action temperature (Tf) needs to match the abnormal temperature of the circuit;
Maintenance temperature (Th/Tc) needs to be higher than the normal operating temperature of the circuit.
Electrical Parameters:
Rated current ≥ circuit operating current;
Rated voltage ≥ circuit open circuit voltage.
Environmental Protection Requirements: Alloys, pins, and other materials must comply with RoHS standards.
4. Where are Thermal Cutoffs (Thermal Fuses) Used?
Household Appliances: Electric blankets, water dispensers, etc.
Electronic Equipment: TVS diodes, varistors, and other transient protection components.
5. Certification Standards of Thermal Cutoffs (Thermal Fuses)
International Certification: UL, VDE, CCC, PSE, etc.
Special Requirements: Some models have passed regional certifications such as JET and BEAB.
6. Precautions for Thermal Cutoffs (Thermal Fuses)
Strictly follow the rated parameters (such as Tm is the maximum temperature limit) when using;
The installation location should be close to the heat source to ensure the temperature response sensitivity.
7. Typical Brands for Thermal Cutoffs (Thermal Fuses)
Bussmann
MERSEN
Littelfuse
Uchihashi
CHINT
SCHURTER
TDK
Vishay
Bourns
And so on…
Thermal Cutoffs (Thermal Fuses) FAQs
1) What is the difference between a thermal fuse and a temperature fuse and a thermal switch?
Temperature Fuse: A type of thermal fuse, both are one-time action devices;
Thermal Switch: Can be repeatedly turned on and off (such as through magnetic field or mechanical control), often used in precision temperature control scenarios.
2) What is the difference between a thermal fuse and a current fuse?
Thermal fuses only respond to temperature changes and have no protection against over-current; current fuses are blown by current overload, and the two are irreplaceable.