(19)
(11) EP 0 191 465 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
22.02.1989 Bulletin 1989/08

(43) Date of publication A2:
20.08.1986 Bulletin 1986/34

(21) Application number: 86101748.1

(22) Date of filing: 12.02.1986
(51) International Patent Classification (IPC)4: H01H 33/91
(84) Designated Contracting States:
CH DE FR GB IT LI NL SE

(30) Priority: 15.02.1985 JP 26286/85

(71) Applicant: HITACHI, LTD.
Chiyoda-ku, Tokyo 100 (JP)

(72) Inventors:
  • Satou, Minori
    Hitachi-shi Ibaraki 316 (JP)
  • Kashimura, Katsuichi
    Takahagi-shi Ibaraki 318 (JP)
  • Koyanagi, Osamu
    Hitachi-shi Ibaraki 319-12 (JP)
  • Hirasawa, Kunio
    Hitachi-shi Ibaraki 316 (JP)

(74) Representative: Beetz & Partner Patentanwälte 
Steinsdorfstrasse 10
80538 München
80538 München (DE)


(56) References cited: : 
   
       


    (54) A puffer type gas blast circuit breaker


    (57) An insulation nozzle (10) for the puffer type gas blast circuit breaker moves together with a movable arcing contact (14). A downstream divergent section of the insulation nozzle (10) includes a first annular triangular groove (34) and a second annular triangular groove (36). The first triangular groove (34) is disposed downstream to a intermediate throat section (32) of the insulation nozzle (10). The second annular triangular groove (36) is disposed downstream to the first annular triangular groove (34) and so dimensioned that an angle (P2) of a line between the downstream edge (40) of the intermediate throat section (32) and downstream ridge (44) of the second annular triangular groove (36) is smaller than an angle (P,) of a line between the downstream edge (40) of the intermediate throat section (32) and the downstream ridge (42) of the first annular triangular groove (34) to the axis of the insulation nozzle (10), whereby part of compressed blast gas is directed to the visinity of the front end portion of a stationary arcing contact (12) to apply a dynamic pressure thereat until the insulation nozzle (10) leaves the stationary arcing contact (12) to thereby prevent sudden pressure drops of the compressed blast gas thereat which causes an electrical breakdown between the arcing contacts (12, 14).






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