for INMR WEEKLY TECHNICAL REVIEW
Too much lightning cause of outage? EGLA being used in China Southern Power Grid.
In many part of the globe, lightning has an adverse impact on reliability of overhead transmission. In southeastern China, for example, lightning has traditionally accounted for as high as 60 percent of all outages recorded on the HV network. For example, transmission line outage rate in bustling Shenzhen, near to Hong Kong, in the past varied from 2.77 to 3.88 per 100 km.
To reduce the extent of this problem, local engineers embarked on a program to equip problematic line sections and highly exposed towers with line arresters having external gap designs (EGLA). Arresters became the preferred choice since, in most cases, alternative solutions for lightning mitigation were not considered practical given the difficulty and expense of lowering the high grounding resistance in mountainous areas.
In order to make the program most cost-effective, the installation process began with identifying specific lines most at risk, based on past lightning strike data and related outage statistics. Moreover, other factors included extent to which towers were prone to shielding failure or whether there was any possibility to avoid problems by increasing insulation levels while still respecting tower clearances.
Interested to know more? Please read: Utility Reduces Lightning Outages With Line Arrester Investment Program
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