IC Realtime HDVR-MX0402-1U5MP-AI2-WEB Product Manual - Page 245

PHILIPS (LCD) 220EW9 25-inch Appendix 6 Compatible Switcher Brand D-LinK D-LinK Ruijie H3C TP-LINK TP-LINK Model DES-1016D DES-1008D RG-S1926S H3C-S1024 TL-SF1016 TL-SF1008+ network working mode 10/100M self-adaptive 10/100M self-adaptive Five network modes: ● AUTO ● HALF-10M ● FULL-10M ● HALF-100M ● FULL-100M 10/100M self-adaptive 10/100M self-adaptive 10/100M self-adaptive Appendix 7 Earthing Appendix 7.1 What Is the Surge Surge is a short current or voltage change during a very short time. In the circuit, it lasts for microsecond. In a 220V circuit, the 5KV or 10KV voltage change during a very short time (about microseconds) can be called a surge. The surge comes from two ways: external surge and internal surge. ● The external surge: The external surge mainly comes from the thunder lightning. Or it comes 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 from the internal of the building such as the air conditioning, elevator, electric welding, air compressor, water pump, power button, duplicating machine and other device of inductive load. The lightning surge is far above the load level the PC or the micro devices can support. In most cases, the surge can result in electric device chip damage, PC error code, accelerating the part aging, 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 use the same distribution box. To protect the device, you need to evaluate its environment, the lighting affection degree objectively. Because surge has close relationship with the voltage amplitude, frequency, network structure, device voltage-resistance, protection level, ground and etc. The thunder proof work shall be a systematic project, emphasizing the all-round protection (including building, transmission cable, device, ground and etc.). There shall be comprehensive management and the measures shall be scientific, reliable, practical and economic. Considering the high voltage during the inductive thundering, the International Electrotechnical Commission (IEC) standard on the energy absorbing step by step theory and magnitude classification 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 the building, personal injury or the property.