Temperature fuse, also known as thermal fuse link (GB9816.1-2013), is a cutting device of temperature sensor circuit. Temperature fuse can sense overheating of abnormal operation of electrical equipment and electronic products, and cut off the circuit to avoid fire. Mainly used in hair dryers, electric irons, rice cookers, electric furnaces, transformers, motors, water dispensers, coffee pots, etc. It should be noted that the temperature fuse can no longer be used after operation, and can only be operated once at the fusing temperature. Then the following mainly explains the related knowledge of temperature fuse.
There are two main types of thermal fuses: alloy type thermal fuse and organic type thermal fuse. Among them, there are two kinds of alloy thermal fuses: axial type and radial type. While the temperature is 76℃-240℃ and the current is 1A-50A. Its main safety certifications are UL, VDE, PSE, CUL, CCC, TUV, etc. In addition, with the improvement of people's environmental awareness, all homogeneous materials require environmental protection materials, such as alloys and pins.
Pay attention to the following points when selecting thermal fuses:
(1) when the circuit is abnormal, the temperature to be disconnected is equal to the measured operating temperature of the temperature fuse;
(2) When the circuit works normally, the temperature is less than or equal to the holding temperature of the temperature fuse;
(3) When the circuit works normally, the current is less than or equal to the rated current of the temperature fuse;
(4) The voltage after the circuit is connected is less than or equal to the rated voltage of the temperature fuse;
Terms related to temperature fuse are interpreted as follows
I. rated operating temperature Rated Function Temperature (Tf)
When the load current of 10 mA is applied, the temperature at which the temperature fuse is opened by heating (for manufacturers to distinguish specifications, the focus should be on the measured operating temperature);
The temperature of the Thermal-link which causes it to change the state of conductivity with a
detection current up to 10 mA as the only load.
The allowable deviation tolerance: TF 0/–10 c (gb9816, en60691, k60691).
The allowable deviation tolerance: TF 7 c (j60691)
Second, the measured action temperature Fusing Temperature
Put it in an oil pool, apply a load current below 10 mA, raise the temperature by 0.5℃~1℃ per minute, and measure the disconnection temperature.
The temperature of the 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℃~1℃/min, with a detection current up to 10 mA as the only load.
Third, keep the temperature: Holding Temperature (Th)
The maximum temperature at which rated current is continuously applied for 168 hours without interruption.
The Maximum temperature at which a Thermal-link will not change its state of conductivity when conducting rated current for 168 h.
IV. Maximum Temperature Limit (Tm)
The maximum temperature that can be tolerated without damaging the mechanical and electrical characteristics within the specified time.
The temperature of the Thermal-link stated by the manufacturer, up to which the mechanical and
electrical properties of the Thermal-link having changed its state of conductivity, will not be impaired for a given time.
V rated current: Rated Current (Ir)
The maximum current allowed to be used in the circuit and safely disconnected for the classification of thermal fuses.
The current used to classify a Thermal-link, which is the Maximum current that Thermal-link allows to carry and is able to Cut off the circuit safely.
VI. Rated Voltage (Ur)
The highest voltage that is used for temperature fuse classification and allowed to be used for circuit and safely disconnected.
The voltage used to classify a Thermal-link, which is the Maximum voltage that Thermal-link allows to carry and is able to Cut off the circuit safely.
Seven, instantaneous overload current ransient Overload Current (Ip)
The maximum transient overload current that the temperature fuse can withstand without destroying its characteristics (the transient overload current that the temperature fuse bears is 15 times of the rated current, and the temperature fuse should not operate for 100 cycles)
A direct current pulse at which the Thermal-link is able to withstand without impairing it’s characteristics.
