【正文】 Lightning protection groundingAbstract The significance of lightning and mitigation on very little money to prevent large losses, and its function is to use scientific means avoid natural disasters. Grounding is to make the system has been included in the lightning protection lightning energy discharge into the earth, and good grounding can effectively reduce the online guide overvoltage, avoid counterattack. Avoid ground is the most important aspect of technology, whether sings rem, induction lightning, or other forms of ray, ultimately the lightning current into the earth. Therefore, no reasonable and good grounding device is can39。t reliably the lightning strikes. The smaller the grounding resistance, e loose flow is quicker, lightning objects the time to maintain high potential more short, the less riskKey Words: Lightning protection。 Grounding。 Current。 potential1 introductionIn recent years, many domestic and foreign standards do not advocate information equipment using independent grounding device, remend the use of mon earthing system. For example, the 2000 edition of the GB5005794 design code for protection of structures in point out clearly: every building itself should adopt mon earthing system to be the buildings within the various grounding are unified to buildings based on, or outdoor grounding device. When the building was hit by lightning, power system voltage and electrical equipment grounding voltage rises at the same time, keep the equipment working voltage constant, so that the electronic equipment from lightning strikes can work normally. Common earthing system usually use the building foundation grounding electrode, the grounding resistance less than 1 ohm in general, if the equipment grounding resistance requirement is lower, should take the minimum value.The ground that has been incorporated into the lightning protection system of lightning energy drain into the earth, good grounding downlead to effectively reduce the voltage on the back, to avoid the occurrence of. In the past some requirements of electronic equipment grounding alone, the purpose is to prevent stray current and transient current in power network disturbance of the normal work of equipment. Before 90 time, forces of the munication navigation equipment electronic tube device, using analog munication mode, analog munication on particularly sensitive to interference, interference, so will take power and munications grounding separate way. Now, the lightning protection engineering fields do not advocate a separate ground. In the IEC standards and ITU standards are not advocating a separate ground, American Standard IEEEStd11001992more sharply pointed out: not remended the use of any kind of socalled separate, independent, puter, electronic or other such incorrect ground as equipment grounding conductor of a connection point. Grounding is the most fundamental aspect of the lightning protection system. The ground is not good, all the measures of lightning protection effect can play. Lightning protection grounding is ground munication stationCode for construction and acceptance of the basic safety requirements, the grounding of PLC belongs to a lowvoltage electrical equipment of single point grounding modeLow voltage electrical equipment of single point grounding mode can be divided into: tandem type single point grounding, parallel type single point grounding, multiple branching of single point grounding.2 single point grounding methodTandem type single point grounding: or first grounding ways. Method : the number of low voltage electrical equipment grounding terminal equipment with the same root near the ground wire connecting, then through this grounding and grounding device. The grounding system is: save manpower, material resources。 while the disadvantage is that: when the public grounding line open circuit, if the grounding system has a device leakage, can cause other equipment which occurred on voltage, a threat to the safety of personnel.Backup ground terminal introducing a grounding line, and then the number of lines at the same time received a grounding device. The grounding system is: when the grounding system in which a device grounding wire broken circuit, will not cause other equipment enclosure voltage, to ensure personal safety. This grounding mode is: if it is not perfect on the interference of high frequency electronic equipment or other highly sensitive electrical equipment, high frequency interference from other devices ( such as converter, intermediate frequency stove thyristor converter parts) will be from the mon place of string, causing the device is not working properly.Multiple branching of single point grounding: or third grounding ways. Grounding method: each equipment grounding terminal alone received a grounding device. Earthing method and second kinds of grounding is the difference: the device has a separate grounding body ( or a change of: received directly from the grounding body recent grounding device ( or grounded source office ), each device in the electrical ground loop on the distance is far more (for example, more than 50meters ) ). This effectively avoids