What is a high voltage fuse?

1. Brief introduction of high voltage fuse:

High-voltage fuse is the most commonly used short-circuit protection switch for 10kV distribution lines and distribution transformers. It has the characteristics of economy, easy operation, and strong adaptability to outdoor environments. It is widely used in 10kV distribution lines and distribution transformers. The primary side is used for protection and equipment switching operations. It is installed on the 10kV distribution line branch line, which can reduce the power outage range. Because it has an obvious disconnection point, it has the function of an isolating switch, creating a safe working environment for the lines and equipment in the maintenance section, and increasing maintenance personnel Sense of security. Installed on distribution transformers, it can be used as the main protection of distribution transformers, so it has been popularized in 10kV distribution lines and distribution transformers. Fuses can be divided into indoor and outdoor types.

(1) Indoor high voltage fuse:

The indoor fuse is a sealed tube fuse filled with quartz sand. When it passes overload current or short-circuit current, the melt melts. The metal vapor and free gas after arcing are subjected to high temperature and high pressure, and the quartz sand is sprayed into it. The gap between the quartz sand surface is cooled and solidified in contact with the quartz sand, which reduces the free gas and metal vapor after the melt is evaporated, so that the current naturally crosses zero and forces the arc to extinguish. When the fuse is blown, the wire of the fuse spring is also pulled off at the same time and ejected from the spring tube. The indoor high-voltage tubular fuse has the characteristics of strong arc extinguishing ability, large breaking capacity, no free gas discharge when breaking the circuit, and capable of generating shut-off overvoltage. It can be completely fused before the short-circuit current reaches the impact value, so this fuse has a current limiting effect.

(2) Outdoor high voltage fuse:

Outdoor fuses are used to protect 10kV power transformers and power lines. It is composed of a fixed support part, a movable fuse tube and a fuse, and the fixed support part is made of porcelain or synthetic insulator. Its working principle is: penetrate the fuse into the fuse tube, tighten the two ends, and place the fuse above the middle of the fuse tube. The upper moving contact is tilted up perpendicular to the fuse tube due to the tension of the fuse. The insulating pull rod pushes the upper movable contact into the upper static contact, into a closed state (closed state) and maintains this state. When the protected line fails and the fuse is blown by the fault current, an arc is formed. The arc extinguishing tube decomposes a large amount of gas under the action of the arc high temperature, so that the pressure in the tube increases sharply, and the gas is sprayed out at high speed, forming a strong arc. The arc is blown in the longitudinal direction, so that the arc is quickly elongated and extinguished. At the same time, due to the fuse blown, the pulling force of the fuse disappears, and the locking mechanism is released. The fuse tube is under the action of the elastic force of the upper static contact and its own weight. , Flip and fall around the lower axis, forming an obvious disconnection distance. Disconnect the circuit and remove the faulty line or faulty equipment.