Precautions for fuse

In view of the excellent short-circuit protection performance of fuse, it is widely used in high and low voltage distribution system, control system and electrical equipment. As a protector of short-circuit and overcurrent, it is one of the most common and important protection devices.

In the application, attention should be paid to the precautions for the use of fuses, daily patrol inspection and maintenance.

Precautions for fuse use:

1. The protection characteristics of the fuse shall adapt to the overload characteristics of the protected object. Considering the possible short-circuit current, the fuse with corresponding breaking capacity shall be selected;
2. The rated voltage of the fuse shall adapt to the line voltage level, and the rated current of the fuse shall be greater than or equal to the rated current of the melt;
3. The rated current of fuses at all levels in the line shall be matched accordingly, and the rated current of the previous level must be greater than that of the next level;
4. The fuse melt shall be matched according to the requirements. It is not allowed to increase the melt at will or replace the melt with other conductors.

Patrol inspection of fuse:

1. Check whether the rated value of fuse and melt matches with the protected equipment;
2. Check the appearance of the fuse for damage and deformation, and the porcelain insulation for flicker and discharge traces;
3. Check whether the fuse is in good condition and whether the contact points are tight;
4. Whether the fuse signal indicator of the fuse is normal.

Use and maintenance of fuse:

1. When the melt melts, carefully analyze the causes of fusing. The possible causes are:

1) Normal fusing due to short-circuit fault or overload operation;

2) The melt is used for too long, and the melt is broken by mistake due to the change of melt characteristics due to oxidation or high temperature during operation;

3) There is mechanical damage during melt installation, which reduces its cross-sectional area and causes false breaking in operation.

2. When disassembling and replacing the melt, it is required to:

1) Before installing a new melt, find out the cause of melt fusing. If the cause of fusing is not determined, do not disassemble and 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, check the internal burn of the fuse tube. If there is serious burn, replace the fuse tube at the same time. When the porcelain melting pipe is damaged, it is not allowed to replace it with pipes of other materials. When replacing the melt of filler fuse, pay attention to filling the filler.

3. The fuse shall be maintained simultaneously with the power distribution device:

1) Clean the dust and check the contact condition of the contact point;

2) Check whether the appearance of the fuse (remove the fuse tube) is damaged or deformed, and whether the porcelain parts have discharge and flicker marks;

3) Check whether the fuse and melt match the protected circuit or equipment. If there is any problem, investigate it in time;

4) Pay attention to check the N line in TN grounding system and the grounding protection line of equipment. Fuses are not allowed;

5) When maintaining and checking the fuse, cut off the power supply according to the requirements of safety regulations, and do not take off the fuse tube with electricity.