Earthing 283EarthingAppendix 7.1 What Is the SurgeSurge is a short current or voltage change during a very short time. In the circuit, it lasts formicrosecond. In a 220V circuit, the 5KV or 10KV voltage change during a very short time (aboutmicroseconds) can be called a surge. The surge comes from two ways: external surge andinternal surge. The external surge: The external surge mainly comes from the thunder lightning. Or itcomes from the voltage change during the on/off operation in the electric power cable. The internal surge: The research finds 88% of the surge from the low voltage comes fromthe internal of the building such as the air conditioning, elevator, electric welding, aircompressor, water pump, power button, duplicating machine and other device of inductiveload.The lightning surge is far above the load level the PC or the micro devices can support. In mostcases, the surge can result in electric device chip damage, PC error code, accelerating the partaging, data loss and etc. Even when a small 20 horsepower inductive engine boots up or stops,the surge can reach 3000V to 5000V, which can adversely affect the electronic devices that usethe same distribution box.To protect the device, you need to evaluate its environment, the lighting affection degreeobjectively. Because surge has close relationship with the voltage amplitude, frequency,network structure, device voltage-resistance, protection level, ground and etc. The thunderproof work shall be a systematic project, emphasizing the all-round protection (includingbuilding, transmission cable, device, ground and etc.). There shall be comprehensivemanagement and the measures shall be scientific, reliable, practical and economic.Considering the high voltage during the inductive thundering, the International ElectrotechnicalCommission (IEC) standard on the energy absorbing step by step theory and magnitudeclassification in the protection zone, you need to prepare multiple precaution levels.You can use the lightning rod, lightning strap or the lightning net to reduce the damage to thebuilding, personal injury or the property.The lightning protection device can be divided into three types: Power lightning arrester: There are 220V single-phrase lightning arrester and 380Vthree-phrase lightening arrester (mainly in parallel connection, sometimes use seriesconnection ) You can parallel connect the power lightning arrester in the electric cable toreduce the short-time voltage change and release the surge current. From the BUS to thedevice, there are usually three levels so that system can reduce the voltage and releasethe current step by step to remove the thunderstorm energy and guarantee the devicesafety. You can select the replaceable module type, the terminal connection type andportable socket according to your requirement. Signal lightning arrester: This device is mainly used in the PC network, communicationsystem. The connection type is serial connection. Once you connected the signal lightning
