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Basic knowledge about grouding
Nov 23 , 2021
When a lightning wave hits a tower or lightning conductor, most of the lightning current will flow into the ground through the grounding device. If the grounding resistance is too high, the lightning current will generate a very high voltage on the top of the tower, causing the insulator to flash over and cause the line to trip. In recent years, power outages caused by lightning strikes have...
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Thunder and lightning
Nov 25 , 2021
As we all know, when the charge in a thunderstorm cloud reaches a certain amount, a strong electric field is formed between different parts of the cloud or between the cloud and the ground. When the charge accumulates to a certain degree,discharge occurs between the cloud and the cloud or between the cloud and the ground. The occurrence of thunder and lightning comes from the acc...
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Low-voltage surge protectors was approved by IEC
Dec 07 , 2021
At the 2021 annual meeting of the International Electrotechnical Commission IEC/SC37A "Low-Voltage Surge Protector (SPD)" held a few days ago, my country’s first international standard proposal in the field of IEC low-voltage surge protectors was approved. The standard name and series number is: IEC TS 61643-05“Low voltage surge protective devices-Part 05: Monitoring device of Surge protecti...
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SPD backup protector
Dec 15 , 2021
As fuses and circuit breakers show insufficient surge current withstand capability when used in conjunction with SPD, it is necessary to improve the surge current withstand capability. Analyzing the influence of circuit breakers with different rated currents on the breaking capacity of the SSD power frequency short-circuit circuit, to summarize the selection points and coordination suggesti...
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Brief introduction to MOV of SPD
Dec 21 , 2021
Metal oxide varistor (MOV) is a semiconductor element with a unique grain boundary structure. Its resistance value decreases sharply with the increase of voltage. It has excellent nonlinear volt-ampere characteristics, as well as high current capacity, the lower residual voltage, no freewheeling and lower cost. That’s why mov has been the first choice to be used in power and signal ports as over-v...
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The hazards of electrostatic discharge
Dec 22 , 2021
Electrostatic discharge (ESD) and electrical fast transients (EFT) cause different hazards to instrumentation systems. Electrostatic discharge produces strong radio frequency radiation in the frequency range of 5 to 200 MHz.The peak of this radiated energy often occurs between 35MHz and 45MHz, and self-oscillation occurs. The resonant frequency of many information transmission cables is usually wi...
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“Thunder and Snow”
Dec 23 , 2021
Thunder is common in summer, because the ground temperature is high, and convective clouds are more likely to form when warm and humid air rises, which creates conditions for lightning. In areas with relatively large undulations, thunder and rain are more common. This is because the warm air is blocked by mountains during the horizontal movement to form convection. In winter, the ground temperatur...
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Concept of neutral and grounding
Dec 29 , 2021
Neutral connection: The neutral point of generators and distribution transformers is called the zero point, and the line drawn from the neutral point is called the neutral line. The metal shell of electrical equipment connected to the neutral line is called Neutral connection. Working grounding: The neutral point of the transformer of the power supply system is directly grounded as the w...
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