Protection against surge protectors To achieve the desired results, attention should be paid to “properly installing suitable surge protectors in the right place”. The choice of surge protectors is important.
1. The distribution of lightning current between various facilities entering the building is as follows: about 50% of the lightning current is discharged into the ground by an external lightning protection device, and another 50% of the lightning current will be in the metal material of the whole system. Make an assignment. This evaluation mode is used to estimate the flow capacity of the surge protector equipotentially connected at the junction of the LPAOA zone, the LPZOB zone, and the LPZ1 zone, and the specifications of the metal wires. The lightning current at this location is a 10/35μs current waveform. In the case of distribution of lightning current in each metal substance: the amplitude of lightning current of each part depends on the impedance and inductive reactance of each distribution channel, and the distribution channel refers to metal substances that may be distributed to lightning current, such as power lines, signal lines, Metal pipe grades and other groundings such as water pipes and metal frames are generally estimated only by their respective grounding resistance values. In the case where it is not certain, it can be considered that the resistance is equal, that is, the average current is distributed among the metal lines.
2. When the power line is introduced overhead, and the power line may be hit by direct lightning strikes, the lightning current entering the protection zone of the building depends on the impedance and inductive reactance of the external lead line, the surge protector discharge branch and the user side line. If the impedance of the inner and outer ends is the same, the power line is distributed to half of the direct lightning current. In this case, a surge protector with direct lightning protection must be used.