Fuse is the simplest protective device, which is used to protect electrical equipment from overload and short-circuit current damage; choose different types of high-voltage fuses according to installation conditions and uses, such as outdoor drop type, indoor type, and high-voltage fuses for some special equipment. The fuse should be selected as a special series; the fuse we often say is the fuse type. The fuse is a metal wire or sheet made of a metal material with a low melting point, which is connected in series in the circuit to be protected. When the circuit or equipment in the circuit is overloaded or fails, the fuse will heat up and melt, thereby cutting off the circuit and achieving The purpose of protecting a circuit or equipment. Engineering principle Its structure generally includes fuse tube, contact conductive part, supporting insulator and base, etc. The fuse tube is filled with fine quartz sand for arc extinguishing.
Fuse is the simplest protective device. It is used to protect electrical equipment from overload and short-circuit current damage; choose different types of high-voltage fuses according to installation conditions and uses, such as outdoor drop type and indoor type. For some special equipment, high-voltage fuses The fuse should be selected as a special series; the fuse we often say is the fuse type.
High voltage fuse engineering principle
Its structure generally includes a fuse tube, a contact conductive part, a supporting insulator and a base, and the fuse tube is filled with fine quartz sand for arc extinguishing. The fuse is a metal wire or sheet made of a metal material with a low melting point, which is connected in series in the circuit to be protected. When the circuit or equipment in the circuit is overloaded or fails, the fuse will heat up and melt, thereby cutting off the circuit and achieving The purpose of protecting a circuit or equipment.
The role of high voltage fuse
The fuse is mainly composed of two parts, the melt and the fuse tube, and external fillers. When in use, connect the fuse in series in the protected circuit. When the current of the protected circuit exceeds the specified value and after a certain period of time, the calorie generated by the melt itself will blow the fuse, breaking the circuit and playing a protective role. utility of care.
High-voltage fuses are mainly used for overload and short-circuit protection of high-voltage transmission lines, voltage transformers, voltage transformers and other electrical equipment.
The structure, use and characteristics of high voltage fuses
(1) Indoor high voltage fuses. Commonly used indoor high-voltage fuses, such as RN1 series and RN2 series products, are all sealed tube fuses filled with quartz sand.
1) RN1 series fuses. RN1 series fuses are mainly composed of fusion tube, melt, brass end cap, quartz sand and so on. The melt is one or several parallel filaments made of copper, silver or constantan. The melt with a rated current of less than 7.5A is made of one or several silver-plated copper wires wound on a ceramic core according to the rated current, and a small tin ball is welded in the middle of the melt. The melt with a rated current greater than 7.5A is made of two kinds of copper wires with different diameters in a spiral shape, and small tin balls are soldered at the joints. A steel indicator melt is installed in the fusion tube, and its lower end is connected with the indicator. When the melt is blown, the indicator is pushed out by the spring.
It is suitable for overload and short-circuit protection of 3-35kV power lines and power transformers.
2) RN2 series fuses. The structure of RN2 series fuses is basically the same as that of RN1 series fuses, but there is only one fuse in RN2 series, and there is no fuse indicator.
It is suitable for the short-circuit protection of 3-35kV voltage transformers. During operation, it judges whether the melt is blown according to the indication of the voltmeter on the secondary side of the voltage transformer.
(2) Outdoor high-voltage fuses. Commonly used outdoor high-voltage fuses, taking RW4-10 and RW9-35 products as examples, are all sealed tube fuses filled with quartz sand.
1) RW4-10 outdoor drop type high voltage fuse. In normal operation, it is connected in series in the line, and the moving contact at the lower part of the fuse tube is pulled tight by the tension of the fuse, then pushed into the upper static contact, and locked into a closed position. When a line fault occurs, the fault current causes the fuse to blow quickly and form an arc. Due to the high temperature of the arc, the arc extinguishing tube decomposes a large amount of gas, which creates a great pressure in the tube, and forms a strong longitudinal blowing arc along the tube, so that the arc is quickly elongated and extinguished. After the fuse is blown, the lower contact of the fuse tube loses tension and turns down, releasing the locking mechanism, and the fuse tube turns and falls under its own weight and the elastic force of the contact, resulting in an obvious disconnection gap.
This drop-type high-voltage fuse adopts a "step-by-step exhaust" structure. In order to prevent water from entering, the upper end is closed during normal operation. When breaking the small fault current, because the upper end is closed to form a single-end exhaust, the pipe maintains a relatively high pressure to blow out the arc generated by the small fault current. When a large fault current is broken, due to the large air pressure, the upper end is blown away and the two ends are exhausted, which effectively blows out the large and small arcs, and effectively prevents the fuse tube from being damaged by large mechanical pressure.
2) RW9-35 outdoor current-limiting fuse. RW9-35 type outdoor current-limiting fuse consists of melting tube, porcelain sleeve, terminal cap, fastening flange, rod support insulator and other parts. The fusion tube is installed in a porcelain sleeve, and the melt is installed in a fusion tube filled with quartz sand filler. It has the advantages of small size, light weight, good arc extinguishing performance, large current breaking energy, strong current limiting ability, convenient maintenance, replaceable melt, etc., which can improve the operation reliability of the power system.
In addition, there are RW5 type suitable for 35~60kV, and RW6-110 type outdoor fuse suitable for 110kV, etc., which are used to protect power lines, transformers, voltage transformers, etc.