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This paper presents an analysis method based on explicit dynamic analysis, enabling detailed and representative investigations of the mechanical effects of low-impedance faults in power equipment. To illustrate the effectiveness of the proposed method, a given transformer design having caused the projection of a heavy chimney/bushing assembly over a significant distance is used as a case study. A comparison about the observed projection distance of this assembly shows that the method provides representative results, thus offering the significant advantage of replacing costly and unpractical tests. The method is then used to study the retrofit measure proposed in this case to retain the chimney, further exemplifying its power to effectively study different design and retrofitting options.Index Terms-Arc containment, explicit dynamic analysis, finite-difference methods, finite-element methods, finite volume methods, internal faults, pressure effects, tank rupture, transformers.

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Hardy S e n i o r Member I n s t i t u t de r e c h e r c h e d'lydro-Qu6bec (IREQ) 1800 montse S t e -J u l i e Varennes, QuBbec, Canada JOL 2PO Abstract -Over t h e last few y e a r s , t h e problem of e x p l o s i o n s i n o i l -i n s u l a t e d equipment as a r e s u l t of low-impedance f a u l t s h a s t a k e n on i n c r e a s i n g proport i o n s , mainly because of t h e h i g h e r c u r r e n t l e v e l s now a v a i l a b l e and t h e aging of t h e equipment.The problem may become c r i t i c a l when t h e e x p l o s i o n is n o t confined t o t h e t a n k and sends o i l o r p r o j e c t i l e s f l y i n g i n t o t h e environment, j e o p a r d i z i n g t h e s a f e t y of surrounding equipment. T h i s paper p r e s e n t s two methods f o r a n a l y z i n g t h e dynamic response of e l e c t r i c a l equipment t a n k s comp l e t e l y f i l l e d w i t h o i l under f a u l t c o n d i t i o n s l i a b l e t o c a u s e e x p l o s i o n s . Both methods s i m u l a t e t h e same i n f i n i t e c y l i n d r i c a l model, s u b j e c t e d t o an e c c e n t r i c a r c , but d i f f e r e n t i r e l y in t h e i r approach. The f i r s t i s based on an a n a l y t i c a l f o r m u l a t i o n of a thin-walled s h e l l c o n t a i n i n g an i n c o m p r e s s i b l e l i q u i d ; t h e s o l u t i o n i s obtained by superposing o r t h o g o n a l components and n u m e r i c a l l y i n t e g r a t i n g t h e e q u a t i o n s of motion.The o t h e r approach i s more g e n e r a l and i n v o l v e s t h e use of t h e h i g h l y s p e c i a l i z e d s o f t w a r e PISCES, adapted f o r arc-induced e x c i t a t i o n .An u n d e r l y i n g i n t e r e s t of t h e proposed methodology i s t h a t i t can be a p p l i e d , a f t e r m o d i f i c a t i o n s , t o t h e a n a l y s i s of p a r t i a l l y f i l l e d equipment such a s d i s t r ib u t i o n t r a n s f o r m e r s .Comparison of t h e computer r e s u l t s p r o v i d e s a means of m u t u a l l y v a l i d a t i n g t h e two methods and t h u s paves t h e way f o r an extended use of PISCES t o complex models w i t h a more r e p r e s e n t a t i v e t a n k c o n f i g u r a t i o n . A few p a r a m e t r i c s t u d i e s performed with t h e a n a l y t i c a l model have pinpointed t h e c r i t i c a l f a c t o r s t o be cons i d e r e d i n t h e d e s i g n of explosion-proof t a n k s f o r e l e c t r i c a l equipment. pBgv1ouswIlRKI n c r e a s i n g concern over t h e problem of e x p l o s i o n s i n o i l -i n s u l a t e d e l e c t r i c a l equipment h a s r e s u l t e d in a s e r i e s of t h e o r e t i c a l and e x p e r i m e n t a l s t u d i e s , m o s t l y on d i s t r i b u t i o n t r a n s f o r m e r s , and f u r n i s h e d a means of i d e n t i f y i n g and u n d e r s t a n d i n g t h e fundamental mechanism t h a t may l e a d t o a c a t a s t r o p h i c f a i l u r e .In some c a s e s , approximate q u a n t i t a t i v e r e s...

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