Lightning Protection with Segmented Diverters

Abstract

Segmented d i v e r t e r s a r e d e s i g n e d t o p r o t e c t radomes and o t h e r d i e l e c t r i c s t r u c t u r e s a g a i n s t punc ­ t u r e f rom d i r e c t l i g h t n i n g s t r i k e s . Radar t r a n s p a r e n c y , l i g h t w e i g h t and e a s e o f a p p l i c a t i o n have c r e a t e d much i n t e r e s t i n t h e s e d i v e r t e r s . S e v e r a l t e s t s e r i e s were pe rform ed t o o b t a i n d a t a f o r u se i n a p p l i c a t i o n . I t was l e a r n e d t h a t t im e t o f l a s h o v e r i s 0 . 7 p s p e r m e t e r o f s t r i p l e n g t h and i s i n d e p e n d e n t o f r a t e o f r i s e w i th ­ i n t h e r a n g e o f r a t e s t h o u g h t t o be t y p i c a l o f l i g h t ­ n i n g . P r o t e c t i o n e f f e c t i v e n e s s s t ems from t h i s s h o r t f l a s h o v e r t im e as compared w i th t h a t f o r a i r o r s o l i d d i e l e c t r i c s . Segmented d i v e r t e r f l a s h o v e r v o l t a g e i s d e p e n d e n t on s t r i p l e n g t h and r a t e o f v o l t a g e r i s e , w i t h f l a s h o v e r o c c u r r i n g a t 500 kV/m when t e s t e d a t t h e cus to mary 1 , 00 0 kV/us r a t e . T e s t s t o d e t e r m i n e s p a c in g r e q u i r e d t o p r e v e n t p u n c t u r e o f a radome wa l l w i t h an a n t e n n a beh in d i t a r e d e s c r i b e d . 30 cm sp a c in g was r e q u i r e d f o r a n t e n n a t o w a l 1 c l e a r a n c e o f 1 . 5 cm b u t d i v e r t e r s may be p l a c e d up t o 60 cm a p a r t i f t h e a n t e n n a i s 15 cm f rom t h e w a l l . A s u c c e s s f u l i n f l i g h t s t r i k e t o an a r r a n g e m e n t based on t h i s d a t a i s d e s ­ c r i b e d .