What is the function of the fuse and the fuse?
The fuse is also called a fuse, and the IEC127 standard defines it as "fuse link" (fuse-link) ". It is a kind of electrical components installed in the circuit to ensure the safe operation of the circuit. The role of the fuse is: when the fault or abnormal circuit, with the current increasing, and increase the current may damage the circuit in some important devices or expensive devices, there may even cause a fire burned circuit. If the circuit correctly placed the fuse, the fuse will be so in the abnormal current increases to a certain height and a certain time, the fuse cut off the current, so as to protect the safe operation of the circuit. The earliest fuse was invented by Edison more than and 100 years ago, and it was originally used to protect the incandescent lamp, because it was not well developed in the industrial technology at that time. What is the working principle of the fuse? Fuse fusing principle:
As we all know, when the current flows through the conductor, the conductor will have a certain resistance, so the conductor will be hot. And heat follow this formula: Q=0.24I2RT; Q is the heat, the 0.24 is a constant, I is the current flowing through the conductor, R is the resistance of a conductor, T is the current through the conductor time; so the formula we can see that the principle of simple fuse. ??
When the material and the shape of the fuse fuse are determined, the resistance of the fuse R is relatively determined (if the resistance temperature coefficient of the material is not considered). When the current flows through it, it will heat, with the increase of the time the heat is also increased. The size of the current and the resistance heat generating speed, fuse structure and its installation condition to determine the heat dissipation rate, if the speed is less than the heat generated in the heat dissipation rate, the fuse is not fuse. If the rate of heat generation is equal to the speed of heat dissipation, it will not fuse in a long time. If the heat generation rate is greater than the speed of heat dissipation, then the heat generated will be more and more. And because it has a certain specific heat and mass, the increase in its heat on the performance of the temperature rise, when the temperature rises above the melting point of the fuse fuse will fuse. This is the working principle of the fuse. We should know from this principle that you must carefully study the physical characteristics of the material you selected when designing a fuse and make sure that they have the same size. Because these factors have an important role in the normal operation of the fuse. Similarly, when you use it, you must install it properly. Judgment and treatment of the fuse fuse:
Standard fuse current is 2.5 times the standard current. That is to say, if there is a standard fuse specification is 1A. then want to make it fuse, at least 2.5A of the current through it
At present, the electrical equipment of the low pressure side is often used to fuse protection. In the operation of a fuse is fused is frequent, if not carefully analyze the reasons that replaced the new fuse, re operation of electrical equipment will have the error of fault, the result may be more serious loss of equipment, to further expand the scope of the accident. Therefore, the reason to fuse, be handled correctly, is an important measure to ensure the safe operation of electrical equipment.
The fuse fuse generally have the following situations:
1, by mistake. In this case, the fuse wire Crimp or other parts, generally do not have serious burns, it is often because the fuse is too small, too small, poor quality or poor mechanical strength, when installing the fuse (piece) with scars, porcelain plate are not fixed or fixed firmly, fuse crimping is not close. The long running time and produce copper fuse gas film gorgeous caused by the increase of contact resistance. All of the above reasons, should be appropriate in the fuse and replace the appropriate treatment after the restart.
2, over load fuse. Occurred in the middle position of fuse, there are few arc burns. In this case, to identify the cause of the load, to prevent the occurrence of overload phenomenon.
3, short circuit fuse. A severe burn fuse, fuse porcelain plate would make the arc burns. This is probably between the neutral line and phase line or phase and phase short-circuit fault caused by. For this type of fuse, fuse and line with all the equipment after carefully check, find out the fault point and removed, will be updated to fuse operation. But in the low line long end is short, because the wire impedance, short-circuit current may not, nor without serious burn fuse.
4, over voltage fuse. Similar and short fuse, severe burns generally fuse, mainly lightning over-voltage and high voltage into low voltage equipment by identifying the reasons, replacing the fuse can be put into operation new.