Boasting superior short-circuit safeguarding capability, fuses are extensively deployed within high and low voltage power distribution networks, control circuits and various electrical machinery. Serving as key overcurrent and short-circuit protection components, they rank among the most vital protective devices. Proper selection, periodic inspections and systematic maintenance must be carried out throughout their service lifespan.

1. Guidelines for Fuse Deployment

1. The fuse’s protection curve needs to align with the overload tolerance of protected loads. Products with suitable breaking ratings shall be chosen based on the maximum potential short-circuit current of the circuit.

2. A fuse’s rated voltage must correspond to the nominal voltage level of the connected circuit; its rated current shall not be lower than that of the matching fusible link.

3. A selective current grading scheme must be applied to fusible links at different circuit tiers. The upstream link must carry a higher rated current than the downstream one to guarantee tiered fault protection.

4. Only original matched fusible links are permitted for use. It is not allowed to fit oversize links or substitute standard fusible components with any other conductive materials.

2. Regular Inspection Checklist

1. Double-check that the rated parameters of fuses and their internal links are compatible with the protected electrical equipment.

2. Examine the fuse casing for cracks or deformation, and check the porcelain insulating body for burn marks left by electric arc flashovers.

3. Inspect all connecting contact points to ensure tight, intact fitting and no signs of overheating or discoloration.

4. Verify that the blowout signal indicator of each fuse remains fully functional.

3. Fault Diagnosis and Fusible Link Replacement Standards

3.1 Root Cause Analysis for Blown Links

Once a fusible link melts down, conduct a comprehensive investigation into the triggering factors, which generally fall into three categories:

1. Intentional protective melting triggered by short-circuit malfunctions or sustained equipment overloads;

2. Unwanted premature melting caused by long-term oxidation or persistent high operating temperatures;

3. Accidental melting resulting from mechanical harm sustained during installation, which reduces the link’s effective cross-section.

3.2 Operating Specifications for Link Replacement

1. Locate and resolve the underlying circuit fault before mounting a new link. Power restoration test runs are forbidden without prior fault elimination.

2. Confirm the new fusible link’s rated specifications match the parameters required by the protected equipment.

3. Check the interior of the fuse tube for scorching damage. Replace the entire tube if severe burning is observed. Damaged porcelain fuse tubes cannot be replaced with tubes made of alternative materials. Refill arc-suppression filler as instructed when installing new links.

4. Routine Maintenance Together with Distribution Equipment

1. Clear accumulated dust on fuses and reconfirm the tightness and contact status of all connection terminals.

2. Remove fuse tubes to conduct a full visual check, looking for structural damage, distortion and arc flash traces on porcelain components.

3. Reassess the matching performance between fuses and their connected circuits or equipment, and adjust mismatched specifications promptly.

4. Special regulation for TN grounding systems: Fuses shall never be installed on neutral N lines or equipment protective earthing wires.

5. All maintenance and inspection tasks must be performed with power cut in compliance with electrical safety codes. Removing fuse tubes while the circuit is live is strictly prohibited.