1. Rated current: The working current of a fuse (the maximum current that a fuse can maintain normal operation for a long time under normal conditions). 2. Rated voltage: The working voltage of the fuse (the maximum voltage that the fuse can safely withstand at the moment of disconnection). When selecting a fuse, the rated voltage should be greater than the input voltage of the protected circuit. 3. Breaking capacity: When a large overload current (such as a strong short circuit) occurs in a circuit, the fuse can safely cut off (break) the maximum current of the circuit. It is an important safety indicator for fuses. Safe breaking refers to the phenomenon of avoiding splashing, burning, explosion, and other hazards to surrounding components, components, and even personal safety in the breaking circuit. 4. Overload capacity (carrying capacity): The maximum overload current that a fuse can maintain for a specified period of time. UL standard stipulates that the maximum non fusing c
1、 Firstly, analyze the causes of LED bead damage, which are usually caused by the following reasons ① A sudden increase in power supply voltage. ② The temperature inside the lamp is too high ③ Short circuit in the circuit. ④ Failure to do a good job in preventing static electricity during assembly has caused damage to the interior of the LED lamp beads due to static electricity. Although normal voltage and current values are applied, it is extremely easy to cause damage to LED beads ⑤ The voltage and current of the circuit are unstable. 2、 How to protect the circuit of LED beads? Answer: Nowadays, many circuits use fuses for overload protection, but disposable fuses are not suitable for LED lamp products because the circuits of LED beads are very different from those of other products. LED bead circuit overload is caused by the overload protection component, which immediately disconnects the LED bead circuit and automatically restores power supply after the circuit is norma
1. The rated voltage of the selected fuse should be greater than the input voltage of the protected circuit. 2. The rated current of UL specification fuses is determined under laboratory conditions and should be less than 75% of the nominal value during actual use. 3. The rated current of IEC standard fuse tubes can be used at 90% or 100% of the nominal value in actual use. 4. The working life of fuses varies under different operating temperatures. The higher the temperature, the shorter the working life of the fuse; When selecting fuses in practice, it is necessary to refer to the working environment temperature for selection 5. The breaking capacity of a fuse tube is directly proportional to its volume and inversely proportional to the rated voltage. 6. Under more than 100000 pulse impacts, the pulse I2T of the protection circuit should be less than 20% of the rated I2T of the fuse tube.
After the fuse ages, there is no danger of generating the current that should be cut off and the fuse not blowing. The aging of a fuse is equivalent to a decrease in the rated value (current) rather than an increase, resulting in the circuit being cut off at a small overload current or pulse. The durability test in the IEC standard is the life test, which is conducted using a DC power supply at normal temperature: a. Measure the voltage drop until the temperature stabilizes; b. 1.2 times the rated current for 1 hour and cut off the current for 15 minutes. Cycle 100 times; c. Measure the voltage drop after powering on for 1.5 In for 1 hour; d. Measure the voltage drop using the same method as A. Requirement: The voltage drop change before and after the test should not exceed 10%, and the identification should still be clear and distinguishable. There should be no deterioration in the end cap solder joints.
1. Factors that affect the lifespan of fuses: Working environment temperature: Excessive ambient temperature can damage the lifespan of the fuse. Delay type (slow melting type) fuses, such as tin ball type, begin to diffuse towards the metal wire when the temperature is about (150-170 ℃); The temperature at which the fusible metal wire of a quick fuse begins to undergo severe oxidation is approximately (175-225 ℃). Therefore, it is recommended that the delay type fuse fuse should not work above 150 ℃ for a long time, and the fast melting type fuse should not work above 175~225 ℃ for a long time. Pulse current: Continuous pulse impact can generate thermal cycling, leading to diffusion, oxidation, thermal stress, and even acceleration of the fuse. The fuse will gradually age with increasing pulse energy and frequency. Normally, it should be less than 20% to ensure that the fuse can withstand more than 100000 impacts. Other: For example, the length and cross-sectional area of t
A circuit is composed of wires and electronic components, and the parameters of SMD fuses required by different circuits vary. The main parameters of SMD inductors include inductance, allowable deviation, distributed capacitance, rated current, and quality factor. 1. The magnitude of inductance mainly depends on the number of turns (turns) of the inductance coil, the winding method, the presence or absence of a magnetic core, and the material of the magnetic core. Usually, the more coils there are, the denser the wound coils, and the greater the inductance. A coil with a magnetic core has a greater inductance than a coil without a magnetic core. The higher the permeability of the magnetic core, the greater the inductance. So there are many factors that determine the magnitude of inductance. The basic unit of inductance is Henry, denoted by the letter "H". Commonly used units include milliohms (mH) and microohms( μ H) The relationship between them is: 1H=1000mH; 1mH=1000 μ H2. The a