What is a lightning arrester?
A: A lightning arrester is a protection device that can release overvoltage energy and limit the overvoltage amplitude. When in use, install the arrester near the protected device and connect it in parallel with the protected device. Under normal conditions, the arrester does not conduct (at most, only the leakage current of microamperage). When the voltage acting on the arrester reaches the operating voltage of the arrester, the arrester is switched on, and through the large current, the overvoltage energy is released and the overvoltage is limited to a certain level to protect the insulation of the equipment. After releasing the overvoltage energy, the arrester returns to its original state.
How to classify lightning arresters?
A: According to the order of development, that is, protection gap, tubular arrester (including general tube type and new type), valve type arrester, magnetic blow valve type arrester and zinc oxide arrester. At present, the main use of zinc oxide arrester, which protection gap, tubular arrester (including general tube type and new type) and valve arrester can only limit lightning overvoltage, and magnetic blow valve arrester and zinc oxide arrester can limit lightning overvoltage, but also limit the internal overvoltage.
(1) The protection gap is the simplest arrester.
(2) The tubular arrester is also a protection gap, but it can automatically extinguish arc after discharge.
(3) Valve type arrester. In order to further improve the discharge characteristics and protection effect of the arrester, the original single discharge gap is divided into many short series gaps, while increasing the nonlinear resistance (this nonlinear resistance valve is sintered with emery SiC and bonding agent, called silicon carbide sheet), and developed into a valve-type arrester.
(4) Because the magnetic blow valve arrester uses the magnetic blow spark gap, the deionization effect of the gap is enhanced, and the arc extinguishing ability is improved, thus improving its protection effect.
(5) zinc oxide arrester. Zinc oxide arrester is a new type of arrester that appeared in the 1970s of the 20th century. It has the advantages of no gap, continuous flow, residual low pressure and so on.
Magnetic blow valve arrester and zinc oxide arrester can not only limit the lightning overvoltage, but also have the ability to limit the internal overvoltage of the power system.
What are the basic requirements for a lightning arrester?
Basic requirements for lightning arrester:
A: In order to reliably protect electrical equipment and enable the safe operation of the power system, any arrester must meet the following requirements:
(1) The volt second characteristics of the arrester and the volt second characteristics of the protected equipment should be correctly matched, that is, the impact discharge voltage of the arrester should be lower than the impact voltage of the protected equipment at any time.
(2) The voltammetry characteristics of the arrester and the voltammetry characteristics of the protected electrical equipment should be correctly matched, that is, the residual voltage after the action of the arrester is lower than the voltage that the protected equipment can withstand when the same current is passed.
(3) The arc extinguishing voltage of the arrester and the highest power frequency voltage of the installation site should be correctly matched, so that in the case of a fault in the system, the arrester can also reliably extinguish the power frequency continuous arc, so as to avoid the explosion of the arrester.
(4) When the overvoltage exceeds a certain value, the arrester generates a discharge action, and the wire is grounded directly or through the resistance to limit the overvoltage.
