Precautions for fuses
Given the excellent short-circuit protection performance of fuses, they are widely used in high and low voltage distribution systems, control systems, and electrical equipment. As short circuit and overcurrent protectors, they are one of the most widely used and important protective devices.
In application, attention should be paid to the precautions for using fuses, daily inspections, and maintenance.
Precautions for using fuses:
1. The protective characteristics of the fuse should be adapted to the overload characteristics of the protected object. Considering the possible short-circuit current, a fuse with corresponding breaking capacity should be selected;
2. The rated voltage of the fuse should adapt to the line voltage level, and the rated current of the fuse should be greater than or equal to the rated current of the melt;
3. The rated current of each level of fuse melt in the circuit should be matched accordingly, and the rated current of the previous level of melt must be greater than the rated current of the next level of melt;
4. The melt of the fuse should be matched according to the requirements, and it is not allowed to arbitrarily increase the melt or use other conductors to replace the melt.
Inspection of fuses:
1. Check whether the rated values of fuses and melts match the protected equipment;
2. Check the appearance of the fuse for damage or deformation, and check the porcelain insulation for flashing discharge marks;
3. Check whether each contact point of the fuse is intact, tightly connected, and there is no overheating phenomenon;
4. Check if the fuse signal indicator of the fuse is normal.
Use and maintenance of fuses:
1. When the melt melts, it is necessary to carefully analyze the reasons for the melting, which may include:
(1) Normal fusing due to short circuit fault or overload operation;
(2) If the melt is used for too long, it may break due to oxidation or high temperature during operation, resulting in changes in the characteristics of the melt;
(3) There is mechanical damage during the installation of the melt, which reduces its cross-sectional area and causes accidental disconnection during operation.
2. When replacing the melt, it is required to:
(1) Before installing a new melt, it is necessary to identify the cause of melt melting. If the cause of melting is not determined, do not replace the melt for trial delivery;
(2) When replacing a new melt, check whether the rated value of the melt matches the protected equipment;
(3) When replacing a new melt, it is necessary to check the internal burn condition of the fuse tube. If there are severe burns, the fuse tube should be replaced at the same time. When the porcelain fusion tube is damaged, it is not allowed to replace it with another material tube. When replacing the melt of a filler type fuse, attention should be paid to filling the filler.
3. The fuse should be repaired simultaneously with 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 or deformation, and check the porcelain components for discharge flicker marks;
(3) Check whether the fuse, melt, and protected circuit or equipment match, and promptly investigate any issues;
(4) Pay attention to checking the N line and equipment grounding protection line in the TN grounding system, and do not allow the use of fuses;
(5) When maintaining and inspecting fuses, it is necessary to cut off the power supply according to safety regulations, and it is not allowed to remove the fuse tube with electricity.