The core of reducing the risk of fuse failure lies in correct selection, standardized installation, use of qualified products, consideration of environmental factors, and regular maintenance. The following are specific strategies:
Accurate selection:
Rated current: This is the most critical factor. The rated current of the fuse must be slightly greater than the maximum continuous current of the protected circuit during normal operation, but must be less than the safe current carrying capacity of the circuit wires and components.
Avoid being too small: Choosing too small can lead to unnecessary melting (misoperation).
Prohibited from being too large: Choosing too large ("upscaling") is the most common mistake that leads to fuse failure (continuous breakage). This can prevent the fuse from melting in a timely manner during overload or short circuit, resulting in overheating of the wires, equipment damage, and even fire.
Rated voltage: The rated voltage of the fuse must be equal to or greater than the operating voltage of the circuit. Low voltage fuses are used in high-voltage circuits, and when blown, they may not be able to safely extinguish the arc, resulting in continuous arcing or even explosions.
Breaking capacity: The breaking capacity (breaking capacity) of a fuse must be greater than the maximum short-circuit current that may occur in the circuit. In situations with high short-circuit currents (such as main distribution cabinets and input terminals of high-power equipment), if the breaking capacity is insufficient, the fuse may explode when blown, making it impossible to safely cut off the fault current.
Time current characteristics: Select the appropriate melting speed (fast melting, slow melting/delayed melting) according to the needs of the protected equipment.
Fast melting: protects semiconductor devices sensitive to overcurrent, such as transistors and ICs.
Slow melting/delayed melting: Used to protect equipment with surge currents (such as motors, switching power supplies, capacitive loads) and avoid accidental melting caused by normal surges during startup.
Physical size and type: Ensure that the selected fuse model (tube, plug, bolt connection, etc.) matches the fuse holder/bracket perfectly.
Standardized installation and reliable connection:
Use matching fuse holder/bracket: Ensure that the rated parameters of the holder match and the contact is good. Poor quality or aging fuse holders with increased contact resistance can cause heating, affect fuse performance, and even lead to fires.
Ensure good contact: During installation, ensure that both ends of the fuse are tightly, reliably, and have low resistance contact with the clip/terminal. Loose, oxidized, or corroded contact points can generate additional heat, which may cause the fuse to melt abnormally below rated current or the contact point to overheat and fail.
Correct installation torque (if applicable): For bolted fuses, apply the correct torque according to the instructions. Loose connections may cause poor contact, while tight connections may damage the fuse or terminals.
Avoid mechanical stress: Do not excessively bend the pins or subject the fuse body to mechanical stress during installation.
Welding precautions: If fuses need to be welded (such as patch fuses on PCBs), the welding temperature and time must be strictly controlled to avoid overheating and damaging the internal structure of the fuse.
Using high-quality and certified products:
Purchase legitimate brands: Choose fuses produced by reputable manufacturers. Poor quality fuses may use substandard materials, resulting in inaccurate rated parameters, insufficient breaking capacity, or premature aging.
Check the certification mark: Ensure that the fuse has relevant safety certifications (such as UL, CSA, VDE, CCC, PSE, KC, etc.), which indicate that the product has passed independent laboratory safety testing.
Avoid using second-hand or unknown fuses.
Consider environmental factors:
Environmental temperature: High temperature environments can reduce the current carrying capacity of fuses (requiring derating for use). Refer to the temperature derating curve provided by the manufacturer. Low temperatures may also affect the characteristics of certain types of fuses.
Vibration and shock: In high vibration or shock environments, choose fuses with anti vibration design or take additional fixing measures to prevent loose connections or damage to the internal structure of the fuse.
Humidity and corrosion: In humid, dusty, or corrosive environments, choose fuse holders or boxes with corresponding protection levels (IP ratings) and consider using fuses with anti-corrosion coatings (if applicable).
Altitude: In high-altitude areas, the air is thin and the heat dissipation capacity decreases, so it may also be necessary to reduce the rating for use (refer to the manufacturer's guidelines).
Avoid abuse and incorrect operation:
Strictly prohibit "compromise" or "emergency" handling: It is absolutely forbidden to replace fuses with metal wires such as copper wire, iron wire, tin foil, etc. This is an extremely dangerous behavior and completely loses its protective function.
Prohibition of parallel use: It is ineffective and dangerous to use multiple fuses in parallel in order to obtain a larger current. The current cannot be evenly distributed between parallel fuses, which may cause one of them to melt first, and then the others to quickly overload and melt or fail.
Do not repeatedly use disposable fuses: Tube shaped glass/ceramic fuses and patch fuses are disposable and must be replaced with new ones of the same specifications after melting.
Root cause investigation: If the fuse frequently blows, the circuit must be thoroughly inspected to identify and eliminate the true cause of overcurrent or short circuit (equipment failure, short circuit point, overload design, etc.), rather than simply replacing the fuse or a larger one.
Regular inspection and maintenance:
Visual inspection: Regularly check the fuse for physical damage (cracks, burnt marks, bulging) and signs of overheating (discoloration, oxidation, melting) at the contact points.
Replacing aging fuses: In critical or long-term operating equipment, even if the fuse is not blown, the fuse may age due to long-term power on (metal fatigue, oxidation). Based on the equipment maintenance manual or experience, consider replacing fuses that have been in use for too long during preventive maintenance.
Cleaning contact points: During maintenance, ensure that the fuse holder/terminal is clean and free of oxidation and dust accumulation.
Understanding the limitations of fuses:
Fuses are mainly used to prevent overload current and short-circuit current. It cannot prevent voltage fluctuations (such as overvoltage, undervoltage), lightning strikes (unless coordinated with SPD), leakage (requiring leakage protectors RCD/GFCI) and other faults. Ensure that the entire protection plan is well-designed.
Summarize key points:
Accurate selection (current, voltage, breaking capacity, characteristics) is the cornerstone.
Strictly prohibit the use of 'code upgrade'!
Use qualified and certified formal products.
Ensure reliable installation and good contact.
Consider the impact of environmental factors (temperature, vibration).
Eliminate any form of abuse (such as copper wire substitution, parallel connection).
After the circuit breaker is blown, it is necessary to search for and eliminate the fundamental fault.
Regular inspection and maintenance.
By following these principles, the risk of fuse failure (including false tripping and continuous tripping) can be minimized to ensure the safe operation of circuits and equipment.