Alloy Thermal-Link / Alloy Thermal Cutoff (ATCO) is defined as a non-resettable protective device functioning one time only. It is widely used in electrical equipment. ATCO is mainly consist of fusible alloy, flux resin, case, sealant and lead wires. Normally, fusible alloy is jointed to the two lead wires. Under abnormal conditions, when the temp. reaches to the fusing temp. of ATCO, the fusible alloy melts and quickly retracts to the two lead wire ends with the aid of the flux resin and disconnects the circuit completely.
How is Thermal-Link Fusing
TCO
Thermal-Link
A non-resettable device incorporating a THERMAL ELEMENT which will open a circuit once only when exposed for a sufficient length of time to a temperature in excess of that for which it has been designed.
— (IEC 60691)
ATCO
Alloy Thermal-Link
Alloy Type Thermal-Link, Alloy is the thermal element.
Tf
Rated Functioning Temp.
The temperature of the Alloy Thermal-Link which causes it to change the state of conductivity with a detection current up to 10 mA as the only load.
— (IEC 60691)
Tolerance: Tf + 0 / - 10 °C (EN 60691, K60691).
Tolerance: Tf ± 7 °C (J60691).
Fusing Temp.
The temperature of the Alloy Thermal-Link which causes it to change its state of conductivity is measured with silicone oil bath in which the temperature is increased at the rate of 0.5 °C to 1 °C / minute, with a detection
current up to 10 mA as the only load.
— (IEC 60691)
Th
Holding Temp.
The Maximum temperature at which a Alloy Thermal-Link will not change its state of conductivity when
conducting rated current for 168 hours.
— (IEC 60691)
Tm
Maximum Temp. Limit
The temperature of the Alloy Thermal-Link stated by the manufacturer, up to which the mechanical and electrical properties of the Alloy Thermal-Link having changed its state of conductivity, will not be impaired for a given time.
— (IEC 60691)
Ir
Rated Current
The current used to classify a Alloy Thermal-Link, which is the Maximum current that Alloy Thermal-Link allows to carry and is able to cut off the circuit safely.
— (IEC 60691)
Ur
Rated Voltage
The voltage used to classify a Alloy Thermal-Link, which is the Maximum voltage that Alloy Thermal-Link allows to carry and is able to cut off the circuit safely.
— (IEC 60691)
In
Nominal Discharge Current
Being able to withstand 15 peak currents of waveform 8 / 20 μs to test the product's durability of withstanding pulse current.
— (UL 1449)
Imax
Maximum Discharge Current
Bing able to withstand 1 peak current of waveform 8 / 20 μs to test maximum pulse current that the product can with stand.
— (UL 1449)
CP Wire
Tinned Copper Plated Wire.
Through Hole
Radial，Axial
● Electric Blankets
● Electric Aroma Diffusers
● Home Electrical Appliances
● Motors
● Lamps
● Switched-Mode Power Supplies
● Transformers
SETsafe | SETfuse Quality Policy
Provide Industry-Leading Products
Raw-materials Supplier
Select critical raw materials: Must be from a manufacturer with quality management system (ISO9001, IATF16949) certification.
Formulate corresponding incoming inspection specifications (01-QA-06-xxx) for each key material according to design data such as material technical indicators.
Testing Equipment and Tools
Projector, Tool Microscope, Salt Spray Tester, Universal Material Testing Machine, Spectrum Analyzer, Function temperature tester, Tension meter, DSC tester etc.
Manufacturing Process
Function temperature test and Online Inspection and Testing (Function 100% Automatic Testing).
Document
Process Flow Chart.
Failure Mode and Effects Analysis (FMEA).
Quality Control Flow Chart (QCFC).
Standard Inspection Procedure (SIP).
Work Instruction (WI).
Online Testing and Inspection
Resistance test system (100% Automatic Testing).
100% Visual inspection, Fuse aid detection, Soldering appearance CCD detection.
etc.
IPQC(In Process Quality Control) Inspection
AQL(MIL-STD-105E), Dimensions Inspection, Function Test, Visual Inspection.
1. When atmosphere pressure is from 80 kPa to 106 kPa, the related altitude shall be from 2000 meter to -500 meter.
2. Operating voltage less than rated voltage of ATCO, operating current less than rated current of ATCO.
3. Do not touch the ATCO body or lead wires directly when power is on, to avoid burn or electric shock.
Replacement
ATCO is a non-repairable product. For safety sake, it shall be replaced by an equivalent ATCO from the same manufacturer, and mounted in the same way.
Storage
Do not store the ATCO at the high Temp., high humidity or corrosive gas environment, avoid influencing the solder-ability of the lead wires, the product shall be used up within 1 year after receiving the goods.
Installation
Make Sure the Temp. of Installation Position.
1. It is recommended that a dummy ATCO with inbuilt thermo-couple shall be used to determine the proper Temp.
2. The terminal product should be tested to ensure that potential abnormal conditions do not cause ambient Temp. to exceed the Tm of the ATCO.
3. Mount the ATCO at the location where Temp. rises evenly.
4. The surface Temp. of TCO less than the holding temp of ATCO.
5. The seal or body of TCO must not be burned or over heated.
Installation position of mechanical performance requirements.
1. Do not locate the ATCO in a place where severe vibration always occurs.
2. Ensure that the lead wire is long enough, and avoid actions such as press, tensile or twist.
3. The seal or body of TCO must not be damaged.
Mechanical Connection
Riveting
1. Choose small resistivity riveting material and be riveted.
2. A flexible lead or lead with low resistance should be used to rivet the ATCO.
3. Contact resistance should be minimal, large contact resistance will lead to higher Temp., ATCO Functioning in advance.
Crimping
1. Choose small resistivity crimping material and be riveted.
2. Crimping process, to ensure that the lead will not be reversed, sealing resin will not be destroyed.
3. Contact resistance should be minimal, large contact resistance will lead to higher Temp., ATCO Functioning in advance.
Soldering
Hand-Soldering
1. Soldering should be carried out according to Table T-1.
2. The thermal element of ATCO is fusible alloy with low melting point, which is jointed with ATCO lead wires. Improper soldering operation (too high soldering Temp. , too long soldering time, too short lead wire etc.) may transfer more heat to the thermal element and ATCO may open in advance.
3. When soldering conditions are more severe than those listed in Table T-1, a heat sink fixture should be used between soldering point and ATCO body.
4. When soldering, please do not pull / push or twist ATCO body or lead wires.
5. After soldering, let it naturally cool for longer than 20 seconds. During cooling, never move the ATCO body or lead wires.
Wave Soldering
The wave soldering parameters as Table T-2, for reference only, when ATCO is for practice use, you need to do some
validation experiments. For example, using X-RAY to see the fusible alloy of ATCO whether damage after wave soldering.
Lead Wire Forming
1. If lead wire has to be bent, please pay attention to the distance between body and bending point. Refer to Table T-3, T-4.
2. When bending leads, please use pincher or similar tools to fix the product as shown in Fig.T-2, T-3, to avoid damaging the product.
3. During forming and mounting, lead wire should not be cut, nicked, bent sharply, to avoid breaking the product.
4. Tangential forces on the leads must be avoided (i.e. pushing or pulling on the leads at angle to ATCO body) as such
forces may damage the seal of ATCO.
SETsafe | SETfuse
SET
Thermal-Link(ATCO) Catalog
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WHY DO WE HAVE TO ADD A THERMAL FUSE TO THE APPLIANCES
We use too many electrical appliances in our lives, such as induction cookers, rice cookers, electric water heaters, electric heaters, coffee machines, waffle machines, and so on. Under normal circumstances, there will be a control panel inside. The Control Management Chip technology will detect the ambient temperature. Usually, the NTC temperature sensing element is used, according to different heating process requirements, the heater controls work to achieve the desired temperature setting. Although the control chip turns off the heater when the proper temperature is reached, the heater is a very dangerous device. If the NTC fails or the control chip fails to turn off the power supply of the heating element, it may cause safety accidents such as an explosion or fire. Therefore, the independent design of temperature detection and control is not completely reliable and cannot pass the safety certification. So that is why we must add a thermal fuse to achieve double protection!
Over Temperature Protection（55）
Thermal-Link (ATCO)-Alloy Type（39）
Thermal-Link (DC-ATCO)-DC Alloy Type（12）
Thermal-Link (OTCO)-Organic Type（2）
Thermal Protector (TMS)-Resettable（2）
Over Voltage Protection（207）
Transient Voltage Suppression Diodes (TVS Diodes)（35）
ESD TVS Diode Arrays (ESD TVS)（43）
Thyristor Surge Suppressors (TSS)（9）
Gas Discharge Tube (GDT)（18）
Metal Oxide Varistor & MOV Disk（32）
Metal Oxide Varistor & MOV Disk-Standard Type（24）
Metal Oxide Varistor-High Surge Type（4）
MOV Disk-Lightning Protection Type For T1（4）
Thermal Fuse & MOV (TFMOV)（19）
Thermal Fuse Varistor (TFV)（3）
Thermal Fuse & MOV (TFMOV) （13）
Thermally Protected Varistors (TFMOV)（3）
Surge Protective Devices Module (SPD-M)（10）
Surge Protective Device (SPD)（28）
SPD (Low-voltage Power Systems)（19）
SPD (PV System)（3）
SPD (Outdoor Lighting)（5）
SPD (Signaling Networks)（1）
Over Current Protection（39）
Miniature Fuses（22）
Cartridge Fuse-links (CFL)（7）
Sub-miniature Fuse-links (SFL)（2）
Surface Mount Fuse-links (SMFL)（4）
Fusible Wirewound Resistor (RXF)（2）
Thermal-Link & Fusing Resistor (TRXF)（5）
Thermally Protected Resistor (TPR)（2）
Inrush Current Limiting NTC Thermistor (NTC)（9）
Ceramic Positive Temperature Coefficient Thermistor (PTC)（1）
Low Voltage Fuses (LV Fuses)（7）
Active Protection（7）
idea Thermal-Link (iTCO)（5）
Thermal Break Protector (TBP)（2）
Suitable for Over Current Protection Products（2）
SET Fuse-link Clip (SFC) - Suitable for Cartridge Fuse-links (CFL)（1）
Fusehold - Suitable for Photovoltaics (PV)（1）
Φ5 x 20 mm Compatible with Cartridge Fuse-links (CFL)（1）
Φ10 x 38 mm Compatible with Low Voltage Fuses (LV Fuses）（1）
