Analysis on the Non-Operation of a DC Arrester Monitor at the Converter Station Pole Bus

The monitor is connected in series to the earth terminal of the metal oxide arrester and is used to record the number of actions of the arrester as well as the leakage current. JB/T 10492–2011 and GB/T 24845–2018 specify the operating current of the monitor at the standard 8/20 µs waveform, while no requirements are made for other impulse current waveforms. In actual system operation, the current waveform flowing through the arrester is not always the standard 8/20 µs lightning current waveform, which may lead to the situation that the arrester monitor does not operate. In this paper, for the fault case that a DC arrester monitor at the converter station pole bus does not operate, the experimental work was carried out to analyse the causes. The results show that the longer the current waveform and the slower the wavehead, the larger the operating current of the arrester monitor. It is further inferred that in this fault case, the wider (approx. 6.5 ms) duration of the current waveform resulted in a larger current amplitude than that at 8/20 µs test waveform to trigger the monitor operation, and this operating current is likely to be greater than 700 A.