Discussion: Building Lightning Protection For The Door Intercom And Precautions
HC intelligent home network Convective weather into the spring increase, storm, lightning weather occur, and lightning strikes caused casualties and property loss is shocking. Convective cloud lightning in the air between the ground and between the discharge phenomenon, instantaneous discharge voltage up to hundreds of millions of volts, the impact of current up to tens and even hundreds of thousands of amperes lightning a serious threat to lives and property. In particular, building intercom outside the door, subject to the possibility of more lightning, Lin’an City in 2008, more than 100 families building intercom door lightning Jihuai situation, had some building intercom door several times by lightning Jihuai to great use of user inconvenience caused, but also caused great economic losses. Through the investigation of these lightning events and causes of, destroying the main components is the power supply box, circuit board, the speech machine, lightning hit the main ways are:
(1) Thunderstorm for. Thunderstorm for a direct blow to the object of the lightning, thunder cloud near the ground is induced in the projections on opposite charge, with the ground when the thunder cloud projections between the breakdown strength of electric field strength of air occurs when the breakdown discharge, such Thundercloud projections on the ground called the Thunderstorm for direct discharge breakdown. High profile buildings and their vulnerability Thunderstorm for the building side can be called a flank attack suffered Thunderstorm for mine.
(2) lightning. By lightning facilities next to the metal conductor such as induced indirect blow to the object. Lightning sensor is divided into two kinds of electrostatic induction and electromagnetic induction. The formation of electrostatic induction is due to thunder cloud approaching the ground, the ground lug and top of the sensor out of a large number of opposite charges. When Thundercloud Thundercloud or other objects with other discharges, the projections at the top of the charge build-up soon lost binding, showing a high voltage to lightning in the form of high-speed transmission. The formation of electromagnetic induction in the surrounding space as Thunderstorm for the current rapidly changing magnetic field generated in the vicinity of high voltage metal induction. Lightning does not Thunderstorm for less intense, but it more likely to occur Thunderstorm for much higher. Because Thunderstorm for only in the thunder cloud to ground lightning ground will only result in disaster, while lightning thunder cloud to ground lightning, regardless of, or between thunderclouds on the thunderclouds and lightning are caused by disasters occur. Thunder lightning in a larger context and a number of small local simultaneous lightning over-voltage phenomena, and this induction of high voltage, can signal lines, power lines, telephone lines and other metal wire transfer to far, causing Lightning scope. The lightning attack against the main way to take the following measures to prevent:
One, building intercom door unit product should be mine. PRC Ministry of Public Security industry standard GA/T72-2005 “House Apartments intercom system and electric control security door general technical conditions” 5.6 security requirements that: 5.6.1 Dielectric strength?? System power plug and the introduction of terminal between the exposed metal parts with the shell should be able to withstand GB16769-1997 “security alarm equipment, safety requirements and test methods” provided in Table 2, 45Hz ~ 65Hz AC voltage, electric strength test, lasting 1 minute should be no breakdown and flashover phenomenon.
Majority of buildings currently on the market power intercom door rated at 220V, AC peak or synthetic voltage 190 ~ 250V, electric strength test voltage should be 1.5kV. Meet this requirement, only to meet the requirements of the circuit system, sudden changes, but not against lightning over-voltage, large current attacks. Most residential buildings currently on the market gate intercom had any lightning protection measures. Therefore, building intercom door should have lightning protection devices and grounding.
Building intercom door with power and signal 2 circuit, lightning protection lightning protection devices should include the power and signal function of lightning protection 2. Selection of lightning protection devices shall be the following main technical parameters: (1) Nominal voltage Un. The value should be protected with rated voltage of building intercom gate line, usually marked as 230V/50Hz. (2) Rated voltage Uc (maximum continuous operating voltage). This value indicates the maximum sustained lightning protection device operating voltage. That is able to exert long-term specified in the lightning protection device side, without causing changes in lightning protection device characteristics and activation of protection devices for maximum voltage RMS. Such as 385VAC. (3) Rated discharge current In. It refers to the standard lightning protection devices to impose 8/20 s continuous shock wave provides the number of lightning, the lightning protector can withstand the impact of the current maximum peak value, should be 20kA.
I am an expert from China Computer Parts, usually analyzes all kind of industries situation, such as 14 feet trampoline , round trampolines.
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