• Aucun résultat trouvé

MEASUREMENTS AT CURRENT ZERO IN A SF6 GAS BLAST BREAKER

N/A
N/A
Protected

Academic year: 2021

Partager "MEASUREMENTS AT CURRENT ZERO IN A SF6 GAS BLAST BREAKER"

Copied!
3
0
0

Texte intégral

(1)

HAL Id: jpa-00219127

https://hal.archives-ouvertes.fr/jpa-00219127

Submitted on 1 Jan 1979

HAL is a multi-disciplinary open access archive for the deposit and dissemination of sci- entific research documents, whether they are pub- lished or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

MEASUREMENTS AT CURRENT ZERO IN A SF6 GAS BLAST BREAKER

R. Moll, E. Schade

To cite this version:

R. Moll, E. Schade. MEASUREMENTS AT CURRENT ZERO IN A SF6 GAS BLAST BREAKER.

Journal de Physique Colloques, 1979, 40 (C7), pp.C7-309-C7-310. �10.1051/jphyscol:19797152�. �jpa- 00219127�

(2)

JOURNAL DE PHYSIQUE CoZZoque C7, suppZ6ment au n07, Tome 40, JuiZZet 1979, page C7- 309

MEASUREMENTS AT CURRENT ZERO IN A SF6 GAS BLAST BREAKER

R. Moll and E. Schade.

Brawn Boveri, Research Center CH-5405 Baden, BitzerZand.

INTRODUCTION

P o s t a r c c u r r e n t measurements a r e i m p o r t a n t f o r checking t h e range of v a l i d i t y o f a r c models which q u a n t i t a t i v e l y p r e d i c t t h e p o s t a r c c u r r e n t s i n h.v. b r e a k e r s according t o t h e r e s i d u a l c o n d u c t i v i t y

1

e.g. 1

I .

I n t h e c a s e o f SF6 a x i a l l y blown a r c s however, such measurements p l a c e high demands on t h e measuring equipment because of t h e rap- i d recovery t h a t t a k e s g l a c e . To d a t e o n l y few measurements i n t h i s regime have been r e p o r t e d , and t h o s e were o b t a i n e d under v a r i o u s c o n d i t i o n s 12,3,41. I t has even been s t a t e d t h a t SF6 p o s t a r c c u r r e n t s can- n o t be d e t e c t e d . I n t h e f o l l o w i n g r e p o r t a measuring method i s d e s c r i b e d which d e t e c t s

c u r r e n t s f a r below 1 A 1 5 ) . T e s t s a r e c a r - r i e d o u t w i t h t h i s measuring system ( r e - sponse time T~ < 35 n s ) on a m e t a l vapour- f r e e a x i a l l y blown SF6 a r c .

EXPERIMENTAL SETUP

The nozzle arrangement s e l e c t e d (Fig. 2 ) p e r m i t s u n r e s t r i c t e d o p t i c a l o b s e r v a t i o n s e x c e p t f o r t h e narrow o r i f i c e r e g i o n ( h i g h s p e e d - , s c h l i e r e n photography). The vapour produced by t h e upstream e l e c t r o d e i s drawn o f f through a s m a l l o r i f i c e i n t h e e l e c - t r o d e . A square-wave c u r r e n t p u l s e (1.5 kA, 5 m s ) followed by a decay r a t e of 30 ~ / y s i s g e n e r a t e d by an LC network 161. The a r c forms a s t a b l e plasma Column up-stream, while i t i s g r e a t l y i n f l u e n c e d by turbu- l e n c e downstream (Fig. 3 ) .

The recovery v o l t a g e i s s u p p l i e d by a h.v.

LC network ( F i g . 1 ) . The ' s p a r k gap F i s f i r e d approx. 25 ys b e f o r e t h e end of t h e 1.5 kA p u l s e ( c u r r e n t i n j e c t i o n , F i g . 5,7)

.

The RRRV i s determined by r e s i s t o r R2.

The p o s t a r c c u r r e n t i s determined from t h e v o l t a g e drop a c r o s s t h e 10 Q shunt RS,

which i s s h o r t c i r c u i t e d by t h e f a s t diode D b e f o r e c u r r e n t zero.

Network

1 I l l 1

Fig. 1: HS: vacuum b r e a k e r W : c u r r e n t t r a n s f o r m e r

T : r e s i s t o r / c a p a c i t o r d i v i d e r

T < 5 n s )

KO: bagtery-powered o s c i l l o s c o p e I n t h i s measuring arrangement s t r i c t ' c o a x - i a l d e s i g n o f a l l components must be pre- s e r v e d . Also t h e diode D c o n s i s t s of many c o a x i l l y arranged diodes. I n a d d i t i o n , t h e diode c h a r a c t e r i s t i c s should i n c l u d e a high maximum peak, forward s u r g e c u r r e n t , h i g h r e v e r s e v o l t a g e i n c a s e of a r e s t r i k e o f t h e t e s t s e c t i o n , low r e v e r s e c u r r e n t s , low j u n c t i o n c a p a c i t a n c e and a s h o r t recovery time. Since i t i s n o t p o s s i b l e t o o b t a i n a l l t h e s e requirements simultaneously, t h e most f a v o u r a b l e compromise must be s o u g h t , f o r each measuring t a s k . The response time

T~ of t h e p o s t a r c c u r r e n t measuring device i s l e s s t h a n 35 n s .

RESULTS AND DISCUSSION

The measuring s e t u p enabled p r e c i s e p o s t a r c c u r r e n t i n v e s t i g a t i o n s t o be performed.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19797152

(3)

A g r e a t number o f t e s t s showed t h a t i n t h e c a s e o f i n t e r r u p t i o n measurable p o s t a r c c u r r e n t s ( F i g . 6 ) o c c u r o n l y under c o n d i - t i o n s l y i n g a t t h e l i m i t between e x t i n c t i o n and t h e r m a l r e i g n i t i o n . F i g . 4 shows a p o s t a r c . c u r r e n t measurement d u r i n g r e i g n i t i o n n e a r t h e c r i t i c a l c o n d i t i o n . The p o s t a r c c u r r e n t s measured a g r e e i m a m p l i t u d e and t e m p o r a l e v o l u t i o n w i t h t h e o r e t i c a l v a l u e s

111, a l t h o u g h i n t h e e x p e r i m e n t t h e c u r r e n t decay r a t e i s s e e n n o t t o have a s i n g l e c o n s t a n t v a l u e ( F i g . 5 , 7 ) . To a g r e a t e x t e n t t h e v o l t a g e r i s e (0.27 kV/ps) a t t h e c u r - r e n t z e r o i s l i n e a r . The e x t i n c t i o n l i m i t measured a g r e e s w i t h t h e t h e o r e t i c a l v a l u e s

11

I ,

when an a v e r a g e c u r r e n t decay r a t e (20 A/ps) i s assumed. The l i m i t e d o b s e r v a - t i o n o f p o s t a r c c u r r e n t s l e a d s u s t o be-

F i g . 3 S c h l i e r e n r e c o r d R e i g n i t i o n

l i e v e t h a t i n s u l a t i n g l a y e r s a r e encoun- t e r e d which must b e broken down, and t h a t t h i s i s o n l y p o s s i b l e i n t h e v i c i n i t y o f t h e e x t i n c t i o n l i m i t and o f t e n l e a d s t o r e - i g n i t i o n . I n v e s t i g a t i o n s w i t h o t h e r n e t - works c o n f i r m t h i s a s s u m p t i o n , b u t t h i s phenomenon s h o u l d n o t a f f e c t t h e e x t i n c - t i o n l i m i t .

11

I

Hermann W . , R a g a l l e r K . , I E E E PAS-96 1546-1555 (1977) 12

1

F r i n d G . , IEEE Conference Paper

NO. F 79 288-2 (1979)

131 Kobayashi A . , e t a l . IEEE PAS-97 1304-1312 (1978)

141 Murano M . , e t a l . I E E E PAS-94 1890-1900 (1975)

15 1 Moll R.

,

Schade E . , ISH, Milan 1979 161 Hermann W . , e t a l . IEEE PAS-95

1165-1176 (1976)

m e t a l v a p o u r e l e c t r o d e , ( t u n g s t e n ) SF6 3 - 4 b a r

1- 'U

nO"le; ( T e f l o n )

1 bar

1

e l e c t r o d e ( t u n g s t e n )

-

10 mrn

F i g . 2 T e s t b r e a k e r I n t e r r u n t i o n

Références

Documents relatifs

To test whether the vesicular pool of Atat1 promotes the acetyl- ation of -tubulin in MTs, we isolated subcellular fractions from newborn mouse cortices and then assessed

Néanmoins, la dualité des acides (Lewis et Bronsted) est un système dispendieux, dont le recyclage est une opération complexe et par conséquent difficilement applicable à

Cette mutation familiale du gène MME est une substitution d’une base guanine par une base adenine sur le chromosome 3q25.2, ce qui induit un remplacement d’un acide aminé cystéine

En ouvrant cette page avec Netscape composer, vous verrez que le cadre prévu pour accueillir le panoramique a une taille déterminée, choisie par les concepteurs des hyperpaysages

Chaque séance durera deux heures, mais dans la seconde, seule la première heure sera consacrée à l'expérimentation décrite ici ; durant la seconde, les élèves travailleront sur

A time-varying respiratory elastance model is developed with a negative elastic component (E demand ), to describe the driving pressure generated during a patient initiated

The aim of this study was to assess, in three experimental fields representative of the various topoclimatological zones of Luxembourg, the impact of timing of fungicide

Attention to a relation ontology [...] refocuses security discourses to better reflect and appreciate three forms of interconnection that are not sufficiently attended to