Fuses are an electrical appliance that plays a safety protection role in low-voltage power distribution systems. Fuses are widely used in power grid protection and electrical equipment protection. When a short-circuit fault or overload occurs in the power grid or electrical equipment, the fuse can automatically cut off the circuit to prevent electrical appliances from being damaged. Equipment damage to prevent the accident from spreading.
The fuse is composed of an insulating base (or support), contacts, melt, etc. The melt is the main working part of the fuse. The melt is equivalent to a special wire connected in series in the circuit. When the circuit is short-circuited or overloaded, , the current is too large, the melt melts due to overheating, thus cutting off the circuit. Melt is often made into filaments, grids or sheets. Melt materials have the characteristics of relatively low melting point, stable properties, and easy fusing. Generally, lead-tin alloy, silver-plated copper sheet, zinc, silver and other metals are used. When the melt fuses and cuts off the circuit, an arc will be generated. In order to extinguish the arc safely and effectively, the melt is generally installed in the fuse housing and measures are taken to quickly extinguish the arc.
Fuses have the advantages of simple structure, easy use, and low price, and are widely used in low-voltage systems.
1. Precautions
(1) Precautions for using fuses:
fuse
① The protection characteristics of the fuse should be adapted to the overload characteristics of the protected object. Taking into account the possible short-circuit current, select a fuse with corresponding breaking capacity.
②The rated voltage of the fuse must adapt to the line voltage level, and the rated current of the fuse must be greater than or equal to the rated current of the melt.
③The rated current of the melt of each level of fuses in the line must be matched accordingly, and the rated current of the previous level must be greater than the rated current of the next level.
④ The melt of the fuse must be matched according to the requirements. It is not allowed to increase the melt at will or replace the melt with other conductors.
(2) Fuse inspection:
① Check whether the ratings of the fuse and melt match the equipment being protected.
② Check whether the appearance of the fuse is damaged or deformed, and whether there are traces of flash discharge on the porcelain insulation part.
③ Check whether the contact points of the fuse are intact, tightly contacted, and whether there is overheating.
④ Check whether the blown signal indicator of the fuse is normal.
(3) Fuse use and maintenance:
① When the melt melts, the cause of the melt must be carefully analyzed. Possible reasons include:
1) Normal fuse due to short circuit fault or overload operation.
2) If the melt has been used for too long, the melt will be oxidized or the temperature will be high during operation, causing the melt characteristics to change and causing accidental disconnection.
3) There is mechanical damage during the installation of the melt, which reduces the cross-sectional area and causes mis-opening during operation.
②When replacing the melt, it is required to:
1) Before installing a new melt, find out the cause of the melt melt. If the cause of the melt is not determined, do not replace the melt for trial delivery.
2) When replacing a new melt, check whether the rating of the melt matches the equipment being protected.
3) When replacing new melt, check the internal burns of the fuse tube. If there are severe burns, replace the fuse tube at the same time. When the porcelain fused pipe is damaged, it is not allowed to replace it with pipes made of other materials. When replacing the melt of a packed fuse, pay attention to the filling.
③The fuse should be repaired at the same time as the power distribution device:
1) Clean the dust and check the contact condition of the contact points.
2) Check the appearance of the fuse (remove the fuse tube) for damage and deformation, and check whether the porcelain parts have any traces of discharge flash. 3) Check whether the fuse and melt match the circuit or equipment being protected. If there are any problems, investigate them in time.
4) Pay attention to check the N wire in the TN grounding system and do not allow the use of fuses on the equipment's ground protection wire.
5) When maintaining and inspecting the fuse, the power supply must be cut off according to safety regulations. It is not allowed to remove the fuse tube while the power is on.
4. Fuse adapter
The adapter of the fuse includes a base, a micro-indicator switch and a radiator, etc. The user can negotiate with the fuse manufacturer to customize it as needed.
