Lightning Overvoltage Protection: Analyzing The Core Functions Of Surge Arresters Under Extreme Weather Conditions

During the peak season for severe convective weather in summer, the stable operation of power systems faces severe challenges. Instantaneous high voltage caused by lightning strikes often becomes the culprit for damaging electrical equipment. As an overvoltage protection device, 69 kv lightning arrester plays an irreplaceable role in thunderstorms. It guides the energy of lightning surges entering the line to the ground by changing the charge discharge path, thereby maintaining the system voltage within a safe threshold.

Energy Discharge Path of Abnormal High Voltage

When a thundercloud discharges, generating induced lightning or a direct lightning strike, the bus voltage can instantly surge to several times its rated value. After sensing this voltage change, the resistance of the nonlinear resistor (such as zinc oxide resistor) inside the 9kv 5ka lightning arrester drops rapidly. This change in physical characteristics creates an extremely low impedance path. The lightning current flows along this path to the grounding grid, preventing high voltage from penetrating the insulation layer of transformers or distribution cabinets.

Operating Logic of Surge Arresters at Different Stages

• Critical Trigger Stage: Detects an instantaneous surge exceeding the nominal discharge voltage.

• Conduction Discharge Stage: Utilizes nonlinear volt-ampere characteristics to absorb and discharge enormous lightning energy.

• Interruption of follow current phase: After the lightning current has dissipated, the system quickly returns to a high impedance state, interrupting the power frequency follow current and maintaining grid frequency stability.

Dynamic protection of line insulation strength

Power equipment has limited design insulation levels and cannot withstand unlimited potential rises. The intervention of 9kv lightning arrester in thunderstorms essentially provides a dynamic potential limiting barrier for the equipment. It operates in parallel upstream of the protected equipment, acting before the equipment insulation is damaged. This millisecond-level response mechanism reduces the frequency of short-circuit tripping and extends the service life of power facilities. This protection mechanism plays a fundamental safety support role in substations, transmission lines, and industrial power terminals.