Analysis of the cause of sudden explosion of valve type lightning arrester during operation
The function of lightning rod GPT1-M3 (taking valve type lightning arrester as an example) is to prevent electrical equipment from being affected by dangerous overvoltage caused by lightning. When the spark gap in the lightning arrester breaks down and discharges, the current flows into the ground through the valve resistance, thereby protecting the electrical equipment. However, there may be sudden explosions of lightning arresters during operation, and the reasons are analyzed as follows:
(1) In a neutral ungrounded system, single-phase grounding may cause the non fault relative ground voltage to rise to the line voltage. At this point, although the voltage borne by the lightning arrester is lower than its power frequency discharge voltage, it may still cause an explosion under prolonged overvoltage.
(2) When ferromagnetic resonance overvoltage occurs in the power system, it may cause the lightning arrester to discharge (FS and FZ lightning arresters are not allowed to operate in this situation), thereby burning out its internal components and causing an explosion.
(3) When the line is struck by lightning, the lightning arrester operates normally. However, due to its poor spark gap arc extinguishing performance, if the gap cannot withstand the recovery voltage and is broken down, the arc will reignite and the power frequency continuous current will reappear. In this way, multiple reignitions in the gap will cause the valve resistance to burn out, leading to the explosion of the lightning arrester.