How to distinguish between slow blow fuse and fast blow fuse
May 31, 2022
The fuse can be distinguished from the label: super slow fuse (generally indicated by TT), slow blow fuse (generally indicated by T), medium-speed fuse (generally indicated by M), fast acting fuse (generally indicated by F), very fast facting fuse ( Generally represented by FF). Consult with the salesperson when purchasing a fuse.
1. Current and fuse
Generally speaking, overcurrent can be divided into two categories: surge and fault. Surge overcurrent is mostly caused by charging and discharging during circuit switching or the influence of surrounding circuits. The pulse peak value is large and the duration is short, and the energy released is often not large. Slow blow fuses can withstand such overcurrent shocks without cause a fuse action.
Moreover, the fault overcurrent is continuous. Even if the peak value is not necessarily very high, its energy will far exceed the surge overcurrent. For slow blowing fuses, they will respond quickly and fuse as usual. Therefore, from this point of view, slow blowing fuses The slightly slower action speed not only does not affect its protection function, on the contrary, it strengthens its protection function and avoids the chance of misoperation. It can be used in a wider range of occasions to protect multiple circuits.
The quick-blow fuse has less energy, so the action speed is faster, but the cause is slightly limited, especially in capacitive or inductive circuits. Due to the malfunction of the fuse due to the pulse current, the electrical appliance cannot be started and used at all, no matter how strong its protective performance is, it will not help. Slow melting is generally used to prevent surges, such as excluding the possibility of inrush current.
2. The difference between fast-blow and slow-blow fuses
All are double caps; in this way, the product characteristics and safety performance of fuses; gg", that is, the combination of contact caps and contacts; that is, double caps (inner/outer caps). Compared with ordinary small factories or underground factories, In order to cut corners and reduce costs, single-cover pressure nails "single-top, double-top top" are used: mainly cylindrical cap-type fuses are more common and have a great impact on reliability.
External welding and internal welding": From the manufacturing process of fuses, your statement should refer to the spot welding process of different types of fuses; these are two common fuses, and other types of fuses are used more, such as am, from the appearance of the fuse it can be seen that the solder joints are external soldering, the solder joints are inside, the solder joints are not visible from the outside, this is what you call internal soldering.
"Fast melting and slow melting": In fact, it refers to the different use categories of fuses, which are related to the protected electrical appliances. Fuses for general semiconductor devices (SCR, diodes, triodes, silicon rectifiers) used for protection are usually called fast Fusing, its use belongs to the "aR" category. Generally speaking, slow blowing refers to "type fuses", that is, fuses that generally use a full range of separation capabilities, are generally used for line overload or short circuit protection, and are generally used in conventional factories.
Fuse Fuse has two different types: fast and slow. The main reason is that the response time is different. The essence is that the I2t index is different. Fast-blow fuses are generally used to protect sensitive products from damage. It may cause damage to the equipment and cannot play a protective role. Therefore, the basis for fuse selection depends on the requirements of the actual protection circuit.
3. The performance difference between fast melting and slow melting
It is believed that the faster a fuse encounters a fault current in a circuit, the better and the more protective it will be. In this sense, slow-blow fuses are not as protective as fast-blow fuses, right? It's true that slow-blow fuses move slightly slower than fast-blow fuses under the same overcurrent load conditions, but that's not to say they're slower to react , but it requires more energy to melt, and it can also be said that it not only has an overcurrent reaction, but also has a certain ability to discriminate the overcurrent category or energy size. The delay time during the action can be regarded as a slow fuse. The time for the wire to judge the overcurrent.
Generally speaking, overcurrent can be divided into two categories: surge and fault. The fluctuating overcurrent is mostly caused by the influence of charging and discharging or the circuit switching on the surrounding circuits. The pulse peak value is large, the duration is short, and the energy released is usually small. The slow blowing fuse can withstand this kind of overcurrent impact. But it will not cause a fuse action. Moreover, the fault overcurrent is continuous. Even if the peak value is not necessarily very high, its energy will far exceed the surge overcurrent. For slow blowing fuses, they will respond quickly and fuse as usual. Therefore, from this point of view, slow blowing fuses The slightly slower action speed not only does not affect its protection function, on the contrary, it strengthens its protection function and avoids the chance of misoperation. It can be used in a wider range of occasions to protect multiple circuits. The fast blowing fuse is blown due to less energy. Although the action speed is fast, it is slightly limited in the cause.