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REOMAX FUSE Selection is introduced, and the user guide

2019-07-04 17:24:37 REOMAX Electronic Technology co., LTD Read

REOMAX Circuit Protection Component Products are widely used in power supply, computers, telephones, chargers, household appliances, communications products, all kinds of instrumentation and electrical appliances and other electronic and electrical equipment (REOMAX). When you design the circuit in the operation process, the rated current of the equipment selected exceeds its rated value. Rated value, when the current generated at this time endangers the safety of electrical appliances and leads to fire, the fuse will be disconnected in time due to the fault current, thus protecting the safety of electrical property. How to select the fuse, please refer to the following clauses:


The function of fuses:

1. Normally, the fuse acts as a link circuit in the circuit.

2. Under abnormal (overload) conditions, the fuse, as a safety protection component in the circuit, cuts off and protects the electrical appliances by fusing itself. Our current fuse, temperature fuse and on-board fuse are non-recoverable electronic components for one-time use.

2. The working principle of fuses:

1. Current fuse. When the fuse passes through, the heat transferred by the electric energy increases the temperature of the melt. When the normal working current or allowable overload current passes through, the heat generated diffuses to the surrounding environment through the melt and shell, and the heat released by convection and conduction gradually reaches the balance with the heat generated. If the heat generated is greater than the heat emitted, the excess heat gradually accumulates on the melt, which causes the melt temperature to rise: when the temperature reaches or exceeds the melting point of the melt (when the circuit generates fault current or short-circuit current), the melt will be fused and the circuit current will be cut off, thus playing a safe and safe protection circuit. The role of disaster prevention. (REOMAX) 2. Temperature fuses, which are used for overheating protection, are generally referred to as "temperature fuses". Temperature fuse can be divided into low melting point alloy shape and temperature-sensitive trigger shape, memory alloy shape and so on. (Temperature fuse is used to prevent the temperature of heater or easily heater from being too high to protect, such as hair dryer, electric ironing hopper, rice cooker, electric furnace, transformer, motor, etc.); It responds to the temperature rise of electric appliances. High, regardless of the size of the working current of the circuit. Its working principle is different from "current fuse".

Classification of fuses:

1. It can be divided into 3*10mm, 3.6*10mm, 4*12mm, 5*15mm, 5.2*20mm, 6*30mm and others according to the shape and size.

2. According to fusing characteristics, it can be divided into fast fusing type, medium delay fusing type, delay fusing type, super-fast, super-delay and so on. (REOMAX)

3. According to the breaking ability, it can be divided into low-breaking type and high-breaking type (which can also be divided into enhanced breaking type).

4. According to safety standards (or areas of use), it can be divided into: (UL/CSA (North America) specifications, IEC (China, EU, etc.) specifications, JET/KTL (Japan/Korea) specifications, etc.

Fourth, the basic terms of fuses:

1. Rated current, nominal working current of fuse tube (maximum current that fuse maintains normal operation for a long time under normal conditions), that is, rated current of fuse mark.

2. Rated voltage: nominal working voltage of the fuse (maximum voltage that can be safely withstood when the fuse is disconnected). When choosing fuse, the rated voltage of the selected fuse should be greater than the input voltage of the protected circuit, that is, the rated voltage of the fuse mark.

3. Segmentation ability: When there is a large overload current (such as strong short circuit) in the circuit, the fuse can safely cut off the maximum current of the circuit. It is the most important safety index for fuses. Secure segmenting refers to the phenomenon that no splash, combustion, explosion, etc. endanger the safety of surrounding elements, components or even human beings, occurs in the segmented circuit. That is to say, the fuse identifies the H/L after the rated current value. For example, L means low resolution, H means high resolution.

4. Overload capacity (carrying capacity): The maximum overload current that a fuse can maintain working within a specified period of time. When the current flowing through the fuse exceeds the rated current, the melt temperature will gradually rise after a period of time until it is finally fused. UL standard stipulates that when the fuse meets 2 times rated current, its fuse time should be less than 60 seconds.

5. Fuse Characteristics (I-T): The relationship between the load current of the fuse and the fuse fuse fusing time.

A. Fusibility Curve (IT Curve): A logarithmic coordinate system with load current as X axis and fuse time as Y coordinate, which is a curve formed by the time coordinate points of fuse average fuse under different load current. Each type of fuse has a corresponding curve to represent its fuse characteristics. This curve describes the overload performance of the fuse well/can be used as a reference for fuse selection.

B. Fuse Characteristic Table: A table consisting of several specified representative load current values and corresponding fuse time ranges. All safety standards have been clearly stipulated, which is the most important basis for acceptance of fuses. For example, UL, CSA, JET/KTLA specifications for fast fuse type are: 100% In 4 hours minimum, 135% In 1 hour maximum 200% In 2 minutes maximum IEC 60127-2 GB9364.2 specification single 2 fast fuse type, 100mA~6.3A specifications are: 210% In 30 minutes maximum, 275% In 50 milliseconds-2 seconds, 400% In 10 milliseconds-300 milliseconds, 1000% In 20 milliseconds. Maximum in milliseconds.

6. Melting Thermal Energy Value (IT): The nominal energy required to cut off the current of the fuse fuse, in short, the minimum thermal energy required to make the fuse fuse fuse fuse fuse. Total IT = Melting IT + Flying Arc IT. Melting IT (equivalent to pre-flying arc IT in IEC standard) refers to the energy required from melting to the instantaneous start of the flying arc; flying arc IT refers to the instantaneous start of the flying arc to the instantaneous start of the flying arc.