In low-voltage distribution systems, fuses are a type of electrical appliance that plays a safety protection role. Fuses are widely used for power grid protection and electrical equipment protection. When a short circuit fault or overload occurs in the power grid or electrical equipment, they can automatically cut off the circuit to avoid damage to electrical equipment and prevent accidents from spreading. A fuse is composed of an insulation base (or support component), contacts, melt, etc. The melt is the main working part of the fuse. The melt is equivalent to a special section of wire connected in series in a circuit. When a short circuit or overload occurs in the circuit, the current is too high, and the melt melts due to overheating, thereby cutting off the circuit. Melts are often made into filaments, grids, or sheets. Melt materials have the characteristics of relatively low melting point, stable characteristics, and easy melting. Generally, lead-tin alloy, silver plated co
1. When protecting smooth loads without starting process, such as lighting circuits, resistors, electric furnaces, etc., the rated current of the melt is slightly greater than or equal to the rated current in the load circuit. 2. The melt current of a single motor that operates for a long time can be selected based on the maximum starting current or according to the following formula: IRN ≥ (1.5-2.5) IN In the formula, IRN - rated current of the melt; IN - Rated current of the motor. If the motor starts frequently, the coefficient in the formula can be appropriately increased to 3-3.5, depending on the actual situation. 3. Protecting multiple motors that have been operating for a long time (power supply main) IRN ≥ (1.5-2.5) IN max+ Σ IN IN max - The rated current of a single motor with the maximum capacity. Σ In other words, the sum of the rated current of the motor.
The fuse is mainly composed of three parts: the melt, the shell, and the support, among which the melt is a key component that controls the fusing characteristics. The material, size, and shape of the melt determine the fusing characteristics. Melt materials are divided into two categories: low melting point and high melting point. Low melting point materials such as lead and lead alloys have a low melting point and are prone to melting. Due to their high electrical resistivity, the cross-sectional size of the melt produced is larger, and the metal vapor generated during melting is more. They are only suitable for fuses with low breaking capacity. High melting point materials such as copper and silver have a high melting point and are not easy to fuse. However, due to their low electrical resistivity, they can be made into smaller cross-sectional sizes than low melting point melts. They produce less metal vapor during melting and are suitable for fuses with high breaking capacity.
Spiral fuse: There is a fuse indicator on the upper cover of the melt. Once the melt melts, the indicator immediately pops up and can be observed through the glass hole on the ceramic cap. It is commonly used in machine tool electrical control equipment. Spiral type fuse. The breaking current is large and can be used for short circuit protection in circuits with voltage levels of 500V and below, and current levels of 200A and below. Enclosed fuses: Enclosed fuses are divided into two types: filled fuses and unfilled fuses, as shown in Figures 3 and 4. Fuses with fillers are generally made of square porcelain tubes filled with quartz sand and melt, with strong breaking capacity. They are used in circuits with voltage levels below 500V and current levels below 1KA. The unfilled sealed fuse packs the melt into a sealed cylinder, with a slightly smaller breaking capacity, and is used in power grids or distribution equipment below 500V and 600A. Quick fuse: Quick fuse is mainly used f
Fuses can be divided into high-voltage fuses and low-voltage fuses based on the voltage used. According to the protection objects, it can be divided into fuses for protecting transformers and general electrical equipment, fuses for protecting Voltage transformer, fuses for protecting power capacitors, fuses for protecting semiconductor elements, fuses for protecting motors and fuses for protecting household appliances. According to the structure, it can be divided into open type, semi closed type, tube type, and jet type fuses. The open type fuse has a simple structure, and the melt is completely exposed to the air. It is supported by porcelain columns and has no support, making it suitable for low-voltage outdoor use. When breaking the current, a large amount of sound and light is generated in the atmosphere. The melt of the semi enclosed fuse is installed on a porcelain frame and inserted into a porcelain box with metal sockets at both ends, suitable for low-voltage indoor use.
According to the protection form, it can be divided into overcurrent protection and overheating protection. The fuse used for overcurrent protection is commonly referred to as a fuse (also known as a current limiting fuse). The fuse used for overheat protection is generally called "Thermal cutoff". Thermal cutoff can also be divided into low melting point alloy, temperature sensing trigger and memory alloy (Thermal cutoff is used to protect heating appliances or easily heating appliances from high temperature, such as hair dryer, electric iron, rice cooker, electric stove, transformer, motor, etc.; it responds to the rise in temperature of electrical appliances and does not care about the working current of the circuit. Its working principle is different from "current limiting fuse"). According to the scope of use, it can be divided into: power fuse, machine tool fuse, electrical instrument fuse (electronic fuse), and automotive fuse. According to body integration, it can be divi
MB:+86 13924633629 Ms.vicky
E-mail: waimao@xcfuse.com
Factory :
XC Electronics(Shenzhen)Corp.,LTD
Add: Jinyuan Industrial zone,Heao, Henggang, Shenzhen 518115,China
Shenzhen branch: Shenzhen Xucheng Electronic Commerce co.Ltd
Add: 8-15 Jinyuan Industrial zone,Heao, Henggang, Shenzhen 518115,China
