Lightning current monitoring system for recording multiple lightning strikes

Multiple lightning strikes can destroy electricity equipment,and their measurement helps to understand lightning and develop lightning protection.We propose a live recording system that is capable to record current waveforms of continuous lightning strikes for five and more times.The waveforms can be continuously recorded by sampling the return stroke current in high speed but sampling the current between two return strikes in low speed,meanwhile,in the process of multiple lightning strikes,the time of return stroke current is short,but time of the intermediate current between two return stroke currents is long.The system adopts programmable logic device(PLD)to turn on monitoring devices.With its maximum propagation delay time of 3.5ns,the PLD needs only 0.5 μs to start sampling,which reduces the loss of lightning information,meanwhile,it can sample a lightning current waveform up to 756ms each time.The monitoring system is verified in laboratory,and is also used on transmission lines and other places that are frequently stricken by lightning.We also present a practical current waveform of lightning,which is recorded in Shenzhen,China on Aug.20th,2010.