Arrester is the role of parallel discharge gap or nonlinear resistance, the invasion of mobile radio waves to cut, reduce the protection of equipment over-voltage value. Surge arrester can be used to protect the atmosphere over-voltage, can also be used to protect the operating voltage.
lightning arrester
Lightning arrester: An electrical device capable of releasing lightning or power system operation over voltage energy, protecting electrical equipment from transient over-voltage hazards, and cutting off freewheeling current without causing the system to be short-circuited.
The arrester is usually connected between the live conductor and ground in parallel with the protected equipment. When the over-voltage value reaches the stipulated operating voltage, the arrester immediately moves, flows the electric charge, limits the over-voltage amplitude, protects the equipment insulation;
Voltage is normal, the arrester quickly restored to its original state, in order to ensure the normal power supply system.
The role of arrester is used to protect various electrical equipment in the power system from lightning over-voltage, operating voltage, power frequency transient over-voltage damage and damage to an electrical appliance.
The main types of arrester protection gap, valve arrester and zinc oxide arrester.
Protection gap is mainly used to limit the atmospheric over-voltage, generally used for distribution systems, lines and substations into the line protection.
Valve arrester and zinc oxide arrester for substation and power plant protection, 500KV and below the system is mainly used to limit the atmospheric over-voltage, in the ultra-high voltage system will be used to limit the internal over-voltage or over-voltage Backup protection.
The function of lightning conductor and lightning rod is to guide the lightning from above the protected object and to escape safely to the earth to prevent direct lightning, reduce the electrical equipment (overhead transmission lines and power supply equipment) and the buildings under direct lightning The probability.
The determination of the scope of the lightning protection is a very important factor, in order to calculate how much lightning rod must be installed in a certain space is safe.
Formulas: Under the lightning rod safety zone, one and a half times the needle height.
Description: The size of the lightning protection range is related to its height. Under a certain height, there is a safety zone with a protection radius of 1.5 times the lightning rod height (see below)
r = 1.5h Where r ----- lightning protection radius on the ground, m; h ----- lightning rod height, m.
For a wide range of protection Single lightning rod can not be protected when required double needle or multi-needle protection.
Q & A example:
There is a single lightning rod height of 20m, seeking the protection of the radius of the ground is what?
Solution: protection radius is
r = 1.5h = 1.5 × 20 = 30m
A: The ground protection radius is 30m
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