modern fuses. Reference data

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

modern fuses. Reference data

Free technical library

Encyclopedia of radio electronics and electrical engineering / Reference materials

Comments on the article

A widely used means of protecting electronic equipment components from overloads are fuses. The correct choice of fuses helps prevent the failure of devices that. in turn, reduces the cost of maintenance and restoration of equipment.

In most cases, the fuse has little effect on the protected unit, it is "transparent" to the circuit. Therefore, the choice of fuses can be made at the final stages of device development in accordance with the obtained characteristics. Often the only electrical fuse parameter that the designer is guided by is the rated operating current at which the fuse element blows and opens the circuit. However, when choosing the most appropriate type of fuse, characteristics such as operating time, voltage drop, and ambient temperature must be taken into account.

The trip time determines the interval after which the circuit breaks. This time includes the period of heating and melting of the working element under the influence of a specific current value.

Voltage drop. A fuse fusible element is a thin conductor or film that has some resistance, which causes a voltage drop at the ends of the element. The allowable voltage drop across the element must comply with the standard and is listed in the number of characteristics (Urated). When using fuses in circuits with low supply voltage, this parameter must be taken into account. The recommended minimum circuit supply voltage should be at least 5 times the voltage drop across the fuse.

Temperature. This parameter refers to the ambient temperature directly next to the fuse. To prevent premature fuse blowing, the ambient temperature should not exceed 70°C.

There are currently two groups of fuse standards:

UL standards (Underwriters Laboratory, USA), developed jointly with CSA (Canadian Standards Association, Canada);
IEC standards (International Electrotechnical Commission, Europe).

The most applicable standards of these organizations are: UL248-14. CSA248.14 and IEC60127. Despite the fact that both groups of documents have much in common, they differ significantly in determining the dependence of the operation time of a fusible element on the flowing current.

For the first group, the rated current is calculated as the current at which the fuse must blow, while fuses made according to the IEC60127 standard. should work for a long time. It is this discrepancy that does not allow the production of fuses that fully satisfy both groups of standards.

The main use of fuses is to protect equipment from high currents. Different devices react differently to overcurrent. For some of them, the impact of a short-term current pulse with a large amplitude can be fatal, for others - a slight excess of the rated current, but for a long time. Therefore, fuses are produced with different time parameters: Fast-acting and Time lag.

Fuses of the Fast-acting group are used to protect devices from short-term current surges in circuits where, in normal operation, there are no turn-on surges or pulsating currents. Time-lag fuses are used in circuits with capacitive and inductive loads, where there are turn-on and turn-off transients, surges and current pulses.

Since the 30s of the XX century, miniature fuses have been widely used, which are a glass or ceramic tube with contacts on the ends, 5x20 and 6,3x32 mm in size, in which a conductor that burns out during overload is placed. Ease of use, easy detection of a defective fuse (in glass version) and its replacement, a wide range of currents and voltages, compliance with various standards have made fuses of this type the most common way to protect primary power supply circuits.

Subminiature fuses are very small and are best suited for telecom equipment, data processing devices and modules placed on small printed circuit boards.

SM fuses use technology based on thin metal films. They are widely used in mobile devices. Standard sizes and the possibility of packaging in tapes allow them to be used in soldering stations.

Blade-type fuses have been used in the automotive industry since the early 70s. The use of a special copper alloy for the leads results in the lowest resistance and lowest operating temperature. Due to their low cost and ease of use, they are widely used in low-voltage equipment with operating currents from a few to hundreds of amperes.

Thermal fuses are compact and reliable elements designed to protect against ignition of household appliances and industrial electrical equipment. When the temperature rises to an unacceptable value, the electrical circuit breaks. They are used in power sources, chargers and copiers, in washing machines, irons, hair dryers, etc.

Resettable fuses (multifuse) - new components designed to protect electronic devices from overcurrent or overheating.

The use of fuses requires their replacement after operation. This forces fuse blocks to be placed in easily accessible places for ease of equipment maintenance. The use of self-resetting fuses reduces the recovery time and facilitates the development and maintenance of devices. These fuses use PTC polymers. In the event of an emergency, the polymer, which has a crystal lattice with conductive chains, heats up, passes into an amorphous state and sharply increases its resistance (Fig. 1), thereby preventing the passage of a large current.

Modern fuses

The fuse remains in this state as long as it is under the influence of the factors that caused the operation. After the polymer cools down, it restores its properties and is ready to work again.

See other articles Section Reference materials.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

Energy from space for Starship 08.05.2024

Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>

Random news from the Archive

Computer vision for electric scooter 20.07.2022

Electric bike and scooter manufacturer and rental company Lime has announced plans to introduce Advanced Rider Assistance Systems.

For this, a proprietary computer vision platform was created to detect sidewalk driving. In such cases, the user will be notified of the violation by an audible signal or by forcibly reducing the speed of movement.

Lime will begin testing the new system on 400 scooters in San Francisco by mid-August. By the end of the year, it is planned to expand the pilot project to six cities, including Paris, where the company demonstrated the new technology for the first time.

It is noted that in recent times, many large micromobility services have tried to implement some form of ARAS for scooters. Bird, Superpedestrian, and Neuron rely on location-based systems to track where users drive and park. Voi, Spin and Zipp have tried third-party computer vision technologies.

The company has also been testing third-party computer vision systems to test the viability of this approach. Ultimately, the decision was made to invest in a proprietary technology that would detect and prevent sidewalk incidents.

ARAS systems based on location and computer vision have many supporters. Adherents of the first option note that the location system is cheaper and easier to integrate.

It is also noted that computer vision technology is not yet developed enough to be truly effective. Not to mention, computer vision requires additional hardware that can break or be vandalized on the streets.

Other interesting news:

▪ Pocket infrared thermometers

▪ Electric motor without magnets

▪ Game console Microsoft Xbox One X (Project Scorpio)

▪ rare earth piglets

▪ Pressure sensor Infineon KP234

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Clocks, timers, relays, load switches. Article selection

▪ article About valor, about exploits, about glory. Popular expression

▪ article Which poet ended up in an isolation cell, on the wall of which there was a poster calling for his release? Detailed answer

▪ article Administrative and managerial personnel, engineers, junior service personnel. Standard instruction on labor protection

▪ article Stable smooth range generator (up to 30 MHz). Encyclopedia of radio electronics and electrical engineering

▪ article Two-way communication line. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews