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A high-voltage fuse is an overcurrent protection device used to protect high-voltage power equipment. Its main function is to quickly cut off the fault current by melting the fuse when an overload or short circuit occurs in the circuit, thereby protecting the power equipment from damage. High-voltage fuses are widely used in transformers, transmission lines and distribution systems.
Basic structure
The basic structure of a high-voltage fuse is relatively simple and mainly consists of the following parts:
1. Fuse: This is the core component of the fuse, usually made of silver, copper or other metal wires with good conductivity. When the current exceeds the design value, the fuse quickly melts, thereby cutting off the circuit. The design of the fuse is adjusted according to the current level.
2. Fuse tube: The fuse is installed in the fuse tube, which is generally made of high-temperature resistant and highly insulating materials (such as ceramics, glass or epoxy resin). The function of the fuse tube is to protect the fuse and prevent the arc when the fuse melts from causing damage to the external environment.
3. Terminals and leads: The terminals are used to connect the fuse to the circuit. The lead wires are connected to both ends of the fuse, and the circuit is cut off by the action of the fuse.
4. Arc extinguishing device: High-voltage fuses are usually equipped with arc extinguishing devices, which are mainly used to control the generation of arcs when the fuse melts. The arc extinguishing device can quickly extinguish the arc to prevent further damage to the circuit.
Function
The main functions of high-voltage fuses include:
1. Overload protection: When the current in the circuit exceeds the rated value of the fuse (for example, when the transformer load exceeds the rated capacity), the fuse will melt and cut off the circuit to prevent electrical equipment from being damaged due to overload.
2. Short-circuit protection: In the case of a short circuit, the current increases sharply, and the fuse of the high-voltage fuse melts quickly, cutting off the circuit, thereby protecting the equipment from serious damage caused by the short circuit.
3. Interrupting fault current: The fuse not only provides protection in normal operation, but also interrupts the fault current when a fault occurs in the power grid to prevent the accident from further expanding.
Classification
According to different standards, high-voltage fuses can be divided into the following categories:
1. Classification by purpose
- Protective fuses: Mainly used to protect transformers, motors, mutual inductors and other equipment, and can cut off the circuit in overload and short circuit conditions.
- Current-limiting fuses: When a short circuit occurs, the current-limiting fuse can limit the short-circuit current passing through the fault point to prevent a wider range of damage to the power system.
2. Classification by installation location
- Indoor fuses: Designed for indoor installation, commonly used for the protection of indoor switchgear and power equipment.
- Outdoor fuses: Designed for outdoor substations and lines, and can withstand environmental factors such as wind, rain, and temperature changes.
3. Classification by structural form
- Enclosed fuses: The fuse is encapsulated in a closed container and usually has good arc extinguishing and insulation properties.
- Open fuses: The fuse is exposed to the outside air and is usually used under low voltage conditions, with poor arc extinguishing performance.
4. Classification by current limiting type
- Non-current limiting fuse: Mainly used under low fault current conditions, the rise of short-circuit current cannot be limited after the fuse is blown.
- Current limiting fuse: It can limit the rise of current when short-circuit current occurs, reducing the impact on the equipment.
Application scenarios of high-voltage fuses
High-voltage fuses are mainly used to protect key equipment and lines in power systems. Common applications include:
1. Transformer protection: High-voltage fuses can be used for overload and short-circuit protection of small and medium-sized transformers.
2. Motor protection: In industrial equipment, fuses are used for overload and short-circuit protection of motors to prevent motors from burning.
3. Distribution line protection: High-voltage fuses are widely used in power distribution networks to protect transmission lines and power transformers from fault currents.
Advantages
- Simple structure: High-voltage fuses are compact, easy to install, and relatively simple to maintain.
- Quick response: They can respond quickly and cut off the current when a fault occurs, protecting the equipment from serious damage.
- Economical and practical: Compared with other protective devices (such as high-voltage circuit breakers), high-voltage fuses are low-cost and suitable for use in a wide range of power systems.
Notes
Although high-voltage fuses have good protection functions, they are usually not suitable for frequent operation. The action of the fuse is one-time, that is, once the fuse is blown, it needs to be replaced before it can be put back into use.
