As an indispensable safety component in modern electrical systems, fuses play a vital role. Follow INFINITECH to get the full story.

Content of this article

> Definition, function and classification of fuses

> How to choose the right fuse size

> Brands and recommended and certified standards for fuses

> What is the difference between electric fuses and ordinary fuses

> The difference between fuses and circuit breakers

> How to replace a fuse? Sample fuse replacement process for home and car

The definition of a fuse

A fuse, also known as a fuse, is a simple and effective electrical safety device. Its core function is that when the current in the circuit increases abnormally and exceeds the predetermined safety value, the circuit is quickly cut off by fusing itself to prevent excessive current from causing damage to electrical equipment or causing fire and other safety accidents. This self-sacrificing property makes the fuse an essential element in circuit protection.

What is the purpose of the fuse

The main function of the fuse is to provide overcurrent protection. When the circuit is abnormally high due to short circuit, overload or other failure, the metal wire in the fuse will be blown due to heat accumulation, thus interrupting the current flow and protecting the electrical equipment at the back end from damage. This mechanism ensures the stability and safety of the circuit system.

Details:

1. Overload protection: When the current in the circuit exceeds the rated capacity of the fuse, the fuse will be blown due to heat accumulation, thus cutting off the circuit, preventing excessive current from continuing to flow, and protecting other components in the circuit from damage. This is the most basic and important function of the fuse.

2. Short circuit protection: When a short circuit fault occurs in the circuit, the current will increase sharply, and the fuse can quickly respond to this abnormal current, and prevent the damage of the large current to the entire electrical system by fusing itself to prevent serious consequences such as fire that may be caused.

3. Isolation protection: When it is necessary to maintain the circuit or replace damaged parts, removing the fuse can be used as a simple isolation means to ensure that the part of the circuit is completely free of electricity and ensure the safety of maintenance personnel.

4. Diagnostic instructions: The blown fuse can be used as an obvious indication of the fault, helping to quickly locate the problem and facilitate troubleshooting and repair.

5. Adapt to different needs: fuses have a variety of types and specifications, suitable for different circuit environment and protection needs, including fast fusing, delay fusing, etc., you can choose the right fuse according to the specific application.

Classification and type of fuse

There are many types of fuses, which can be classified according to different standards, and the following are several main ways of classification:

1. Protection form:

   • Overcurrent protection: This is the most common type of fuse used to prevent the current in the circuit from exceeding the safety limit.

   • Overheat protection: Also known as temperature fuse, which fuses when the surrounding or device temperature exceeds the set value, providing overtemperature protection.

2. Scope of use:

   • Power fuses: Used in power distribution systems to withstand higher voltages and currents.

   • Machine tool fuses: Designed for industrial equipment such as machine tools to withstand mechanical vibration and specific current characteristics.

   • Electrical and instrument fuses (electronic fuses) : suitable for precision electronic equipment and instruments to protect sensitive circuits.

   • Automotive fuses: Used in automotive electrical systems, with specific designs and specifications to suit the vehicle environment.

3. Size: divided into large, medium, small and micro, to adapt to the space requirements of different equipment.

4. Rated voltage: divided into high voltage fuse, low voltage fuse and safety voltage fuse, according to the working voltage of the circuit selection.

5. Breaking capacity: high breaking capacity and low breaking capacity fuse, the difference is the maximum short circuit current that can be safely interrupted.

6. Shape: including flat head tube, pointed head tube, guillotine type, spiral type, chip type, plate type, wrap type, patch type, etc. The shape affects the installation mode and application scene.

7. Fusing speed: From very slow to very fast fuses, different applications require different fusing rates to match the protection needs.

8. Standard: According to different regional norms, such as European regulations, American regulations, Japanese regulations fuse, to meet the regulatory requirements of different markets.

9. Type:

   • Current fuse: Common patch fuse, micro fuse, insert fuse, tubular fuse and so on.

   • Temperature fuse: such as RH block type, RP resistance type, RY metal shell, temperature sensitive.

   • Self-restoring fuse: including plug-in, laminated, patch type, can automatically restore the on-state after cooling, suitable for some specific applications.

   • Fast fuses: Suitable for precision electronic devices requiring fast response.

   • Slow blown fuse: suitable for motor starting and other occasions that allow short overload.

   • Glass tube/ceramic tube fuse: common in household appliances, transparent housing for easy inspection of the blown state.

   • NH type fuse: For industrial distribution, high temperature resistance, high breaking ability.

Each type of fuse has its specific application scenarios and performance characteristics, and choosing the right fuse is crucial to ensure the safe operation of electrical equipment.

How to choose the right fuse size?

Select the right fuse to consider the following factors:

• Rated current: should match the maximum normal working current of the protected circuit.

• Voltage level: Ensure that the fuse can withstand the working voltage of the circuit to avoid premature fusing due to high voltage.

• Response time: Fast fuses are suitable for applications that require immediate protection, while slow fuses are suitable for circuits that allow a certain overload time.

• Application environment: Different working environments (such as temperature, humidity, vibration, etc.) have specific requirements for the material and structure of the fuse.

• Specific requirements: Such as explosion-proof, waterproof properties are critical for specific applications.

Fuse brands and recommendations

Well-known fuse brands in the market include NEC, Littelfuse, CONQUER, etc. These brands are known for their high quality, wide product lines and good user reviews. When choosing, you can view product specifications, user reviews and consider the convenience of after-sales service and purchase channels through the brand's official website, e-commerce platform or electronic component distributor platform -INFINITECH.

Certification standard for fuses

Fuse safety certification is an important guarantee of product quality, common certifications include:

• UL (Underwriters Laboratories) : Globally recognized safety certification mark.

• CSA (Canadian Standards Association) : widely accepted safety certification in North America.

• MTTI (Machinery Industry Product Testing Institute) : China's authoritative certification of mechanical and electrical products.

• ICE (Italian Electrotechnical Commission) : one of the most important certifications in Europe.

These certifications ensure that fuses meet international safety standards and provide consumers with an important reference point when purchasing.

What is the difference between electric fuses and ordinary fuses?

The main differences between electrical fuses and ordinary fuses are their design, application, performance parameters and protection characteristics. Here are some specific points of difference:

1. Application field:

   • Electrical fuses are usually designed for specific electrical equipment or systems, such as power transformers, high-voltage switchgear, motor control centers, etc., which need to meet strict electrical safety standards and specific environmental conditions.

   • General fuse is widely used in household appliances, consumer electronic products and other general circuit protection, the design pays more attention to versatility and cost effectiveness.

2. Rated voltage and current:

   • Electrical fuses often withstand higher voltages and greater currents, and are suitable for high-voltage and high-current applications in power systems.

   • Ordinary fuses are suitable for civil or light industrial circuits with lower voltages and currents.

3. Breaking capacity:

   • The electrical fuse has a higher breaking capacity, which can safely interrupt the high energy short circuit current in a short time, reducing the damage to the rest of the system.

   • The breaking capacity of ordinary fuses is relatively low, which is suitable for dealing with small current overload or short circuit.

4. Protection features:

   • Special electrical fuses may have special protection features such as time-delay protection, temperature compensation, or specific fusing curves to suit the protection needs of specialized equipment.

   • Common fuses are mostly quick-blow or standard response designed to provide basic overload and short circuit protection.

5. Structure and material:

   • Electrical special fuses may use more durable housing materials and high-performance internal melts to cope with harsh operating environments and long-term stability requirements.

   • Common fuses may use affordable materials such as plastic housings and common fusing materials.

6. Certification and Standards:

   • Electrical fuses usually need to pass more stringent safety certifications, such as UL, IEC and other industry-specific standards, to ensure reliability and safety in specific electrical environments.

   • Although general fuses also need to follow relevant safety standards, their certification requirements may not be as strict or comprehensive as professional fuses.

The difference between fuses and circuit breakers

In terms of working principle:

• Fuse: A fuse is a disposable protection device that when the current in the circuit exceeds its rating, the conductor (usually a metal wire) in the fuse will be blown due to overheating, thus cutting off the circuit and preventing excessive current from damaging other electrical equipment. Once a fuse is blown, a new fuse is needed to restore the circuit.
• Circuit breaker: A circuit breaker is a reusable device that detects overload or short circuit current through an electromagnetic or thermal sensitive mechanism. When the current is abnormal, the trip mechanism inside the circuit breaker will quickly disconnect the circuit. Unlike fuses, circuit breakers can restore the circuit by manually resetting (usually by pressing a button on the circuit breaker) without the need to replace parts.

In terms of reaction speed:

• The reaction of fuses to current overload is usually direct fuses, especially fast fuses, which respond quickly.
• Circuit breakers, especially those with overload and short-circuit protection, may have different response time Settings, such as overload long delay, short-circuit short delay and short-circuit instantaneous protection, to provide more refined protection and selective protection.

Cost and Convenience:

• Fuses are low cost and easy to install, but need to be replaced once they blow.
• Circuit breakers are more expensive and more complicated to install, but may be more economical in the long run because they can be reused.

Adjustable and intelligent:

• Circuit breakers can provide more adjustability, such as adjusting the overload protection threshold, and some also have intelligent monitoring and remote control functions.
• Fuses usually do not have such adjustability, and their protective characteristics are fixed once manufactured.

Protection selectivity:

• In a complex circuit system, the circuit breaker can better achieve upstream and downstream protection selectivity, that is, in the event of a failure, the circuit breaker closest to the fault point has priority action, reducing the power failure range.
• When using fuses, selective protection is difficult to achieve because fuses usually do not have the ability to stage protection.

The choice of fuse or circuit breaker depends on the specific application scenario, cost budget, ease of maintenance, and the need for precision and flexibility in circuit protection.

How to Change a Fuse (Examples of home and Car fuse changes)

Replacing a fuse is a relatively simple task, but requires careful handling to ensure safety and correctness. The following are the general steps that apply to the process of replacing a home or car fuse in most cases:

Household fuse replacement steps:

1. Safety first: Turn off the relevant power switch or disconnect the main power supply. If you are replacing a fuse in your home, turn off the main power switch and make sure all appliances are turned off.

2. Find the box: Find the box in your home, usually near the meter or in an easily accessible location.

3. Confirm a blown fuse: Open the cover of the fuse box, use a multimeter or observe the appearance of the fuse (usually a blown fuse will have a significant break or discoloration) to confirm which fuse has blown.

4. Select a new fuse: Replace it with a fuse of the same size and current rating according to the instructions in the cover of the safety box or in the user manual. Do not use fuses with higher rated current in case of circuit overload.

5. Replace the fuse: Using rubber gloves or insulated tools, gently remove the blown fuse and insert the new fuse to ensure it is fully installed in place.

6. Reset the power supply: cover the safety box and turn on the main power switch again. Test whether the relevant electrical appliances are working properly.

Car fuse replacement steps:

1. Identify the problem: If an electrical appliance in the car stops working, first suspect that the fuse may have blown.

2. Consult the manual: Look in the car owner's manual to find the location of the fuse box and the fuse layout diagram.

3. Power off: Although it is usually not necessary to disconnect the battery to replace the car fuse, ensure that the vehicle is in the shutdown state before operation.

4. Find a blown fuse: Use the illustration in the manual to find a fuse that may have blown, usually there is a puller tool in the fuse box or you can use tweezers.

5. Check and replace: Gently pull out the suspected blown fuse using a puller or tweezers and check whether the internal wire is broken. Then, replace it with a new fuse with the same ampere value.

6. Test appliances: After the replacement, start the car and test whether the appliances that did not work before are back to normal.

In any case, if you do not feel confident or unsure during operation, the best practice is to contact a professional electrician or auto repair technician for a replacement to avoid potential safety risks.