The fuse is also known as the current fuse, and the IEC127 standard defines it as a "fuse-link". And Rhithers. Finds.ither ...... Results which joitherigma drafts nights' Circuit in the correct placement of the fuse, the fuse will be in the current abnormal rise to a certain height and heat when the fuse itself cut off the current to protect the circuit safe operation
More than a hundred years ago by Edison invented the fuse used to protect the then expensive incandescent, with the development of the times, the fuse protection of electrical equipment from overheating damage, to avoid electronic equipment due to internal damage caused by serious injury.
When the circuit fails or abnormal, accompanied by rising current, and the rising current may damage some important devices in the circuit, it is possible to burn the circuit or even cause a fire. If the circuit is properly placed in the fuse, then the fuse will be abnormal in the current rise to a certain height and heat, when the fuse itself cut off the current, so as to protect the circuit safe operation.
General fuse consists of three parts: First, the melt part, it is the core of the fuse, when the fuse to cut off the role of current, the same type, the same specifications of the fuse melt, the same material, geometric dimensions to the same, resistance The fuse is made of lead and antimony alloy; the second is the electrode part, usually two, it is an important part of the melt and circuit connection, it must have Good conductivity, should not produce a significant installation of contact resistance; Third, the bracket part of the fuse melt are generally slender and soft, the role of the bracket is to melt the three parts and become rigid as a whole easy to install, use , It must have good mechanical strength, insulation, heat resistance and flame resistance, in use should not produce fracture, deformation, combustion and short circuit and so on.
Arc extinguishing device
Power circuits and high-power equipment used by the fuse, not only the general three parts of the fuse, but also the arc device, because the protection of such a fuse circuit is not only a large current, and when the melt occurs when the two The end of the voltage is also high, often the melt has melted (blow) or even vaporized, but the current is not cut off, the reason is in the moment of the fuse in the voltage and current under the action of the fuse between the two electrodes Arc phenomenon. The arc extinguishing device must have a strong insulation and good thermal conductivity, and was negative. Quartz sand is commonly used arc extinguishing materials.
In addition, there are some fuse fuse device, its role is when the fuse action (fuse) after its own appearance changes, easy to be found by maintenance personnel, such as: light, color, pop-up solid indicator.
1. Normal operating current operating at 25 ° C, the fuse current rating is usually reduced by 25% to avoid harmful fusing. Most of the traditional fuses use a material that has a lower melting temperature. Therefore, the fuse is more sensitive to changes in ambient temperature. For example, a fuse with a current rating of 10A is generally not recommended to operate at a temperature greater than 7.5A at an ambient temperature of 25 ° C.
2. Voltage Rating The voltage rating of the fuse must be equal to or greater than the effective circuit voltage. The general standard voltage rating series is 32V, 125V, 250V, 600V.
3. The resistance of the resistor fuse is not important throughout the circuit. Since the fuse resistance is less than 1, the fuse resistance is only a few ohms, so consider this when using a fuse in a low voltage circuit. Most of the fuses are made of a material with a positive temperature coefficient, so there is a difference between the cold resistance and the thermal resistance.
4. Ambient temperature fuse current carrying capacity, the experiment is carried out at 25 ℃ ambient temperature conditions, this experiment is affected by changes in ambient temperature. The higher the ambient temperature, the higher the operating temperature of the fuse, and the shorter its life. On the contrary, running at a lower temperature will extend the life of the fuse.
5. Fuse rated capacity is also known as breaking capacity. Fusing rated capacity is the maximum permissible current that the fuse can fuse at rated voltage. Short circuit, the fuse will be more than the normal working current through the instantaneous overload current. Safe operation requires the fuse to remain in full condition (no burst or break) and eliminate short circuits.