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Experience Sharing of Senior Electronic Engineers Selection Indexes of Protective Devices

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Date:2016-07-10

In an industry that relies on technology for food, technology is a golden stepping stone. Whether it is looking for a job or accompanying salespersons for customer visits, strong technical strength and rich experience in the industry are quite handy. Every master-level engineer has a little white stage to gain experience. Based on the relevant information provided by the FAE technical engineer of Ruilongyuan Electronics, the editor has compiled an industry secret that is conducive to the promotion of no-experienced novices, and masters the selection of protective devices. Indicators, you can also quickly upgrade to a senior electronic engineer.


All functional components and protective components R&D and production suppliers are small branches of enterprises in the electronic components industry, and the small branch of Ruilongyuan Electronics is more focused on providing high-quality circuit protection devices for enterprises and customers. And years of industry experience accumulation has allowed Ruilongyuan Electronics to not only have a batch of loyal customers, but also let engineers organize multiple sets of general-purpose version selection experience. Today, the editor of Ruilongyuan Electronics will share with you.


With the development of the urban economy, the damage caused by the intrusion of induced thunder and lightning waves has greatly increased. Today in the information age, computer networks and communication equipment are becoming more and more sophisticated, and their working environment requirements are getting higher and higher, and the instantaneous overvoltage of lightning and large-scale electrical equipment will be more and more frequently sent and received through power supplies, antennas, and radio signals. Equipment and other lines invade indoor electrical equipment and network equipment, causing damage to equipment or components, personal injury or death, interference or loss of transmission or storage data, and even malfunction or temporary paralysis of electronic equipment, system suspension, data transmission interruption, and local area network Even the WAN was destroyed. The harm is shocking, and the indirect losses are generally far greater than the direct economic losses.


In the process of lightning discharge, due to the strong electromagnetic pulse generated by instantaneous discharge, a surge voltage and current with high amplitude and high rate of change are induced on nearby equipment or electronic circuits, which is devastating to some electronic equipment. This kind of lightning phenomenon is called brief lightning strike or induction lightning strike.


Lightning and surge voltage and current have extremely high amplitudes and current characteristics similar to current sources with extremely high internal resistance. All protective measures need to be developed around these aspects. The basic principle of lightning and surge protection is to smoothly discharge the energy contained in lightning and surges in a preset way and way.


The main indicators to measure the performance of protective components are:


1. Rated working voltage Un: The voltage at which the protective component can maintain a high resistance state. When the voltage at both ends of the protective component is lower than the rated voltage, it will have little impact on the protected circuit and equipment.


2. Residual voltage (voltage protection level) Up: The peak voltage at both ends of the protection component when passing through the nominal discharge current. The residual voltage value is related to the type of protective components and the level of its rated working voltage.


3. Nominal discharge current In: The discharge current that the protection component can withstand many times, and its value is closely related to the current waveform.


4. Response time Ta: The time required from the application of voltage to the time when the voltage across the protective element reaches the operating voltage. Since the current at the defined point of the operating voltage (jump voltage) of most protection components is 1mA, it can also be said that the response time is the time required from the application of voltage to the time when the current through the protection components reaches 1mA.


5. Leakage current: the current passing through the protective components under the rated working voltage. The leakage current is directly related to the rated working voltage of the components.


6. Reverse recovery time trr: the time from the zero-crossing point in the process of the current passing through the protective components from positive to negative to the time when the negative current drops from the peak value to the specified value. Protection equipment used on high-frequency and high-speed communication networks requires protection devices with a short reverse recovery time.


7. Inter-junction capacitance Cj: the capacitance between the two ends of the semiconductor protection component. Protective equipment used on high-frequency and high-speed communication networks requires protective devices with lower capacitance.


For more knowledge about electronic protective components, please pay attention to the official website of Ruilongyuan Electronics: www.ruilon.com


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