At present, the thunderstorm season has arrived, which is the inspection and installation stage before the lightning arrester is put into operation. However, the author found that many power management stations ignored this work and even put lightning arresters that had not undergone power frequency verification into operation on the power grid. This approach is incorrect.
The power frequency AC withstand voltage test is the main item for lightning arrester calibration. The waveform and frequency of its test voltage are close to the actual situation when the lightning arrester is struck, which can effectively measure the defects of internal ionization in the lightning arrester. The use of power frequency AC withstand voltage test to verify lightning arresters has the characteristics of strong authenticity and high accuracy. After testing, although some lightning arresters have no discharge burn marks from the appearance and the porcelain skirt is intact, even measuring their insulation resistance value with a 2500V megger meets the requirements. However, when tested with power frequency discharge voltage, its defects are exposed. Either the leakage current is high or the discharge voltage does not meet the requirements. If this type of lightning arrester is put into operation in the power grid, if the power frequency discharge voltage is low, once it rains and becomes damp, if one phase is unqualified, single-phase grounding will occur, and if two phases are unqualified, phase to phase short circuit accidents will occur; For those with high power frequency discharge voltage, if they are struck by lightning, they cannot discharge to the ground. The strong lightning current will damage electrical equipment or cause dangerous induced overvoltage, and still cannot provide lightning protection.
Therefore, the author suggests that power management departments in various regions should urge relevant users to pay attention to lightning protection work and conscientiously carry out power frequency tests for lightning protection. And unqualified lightning arresters should be destroyed on-site to prevent them from flowing into other places for reinstallation and use.