GB2178596A

GB2178596A - Arc-extinguishing device

Info

Publication number: GB2178596A
Application number: GB08615958A
Authority: GB
Inventors: Hirotoshi Ohishi
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1985-07-09
Filing date: 1986-06-30
Publication date: 1987-02-11
Also published as: DE3621165A1; CN1003265B; CN86104487A; GB2178596B; GB8615958D0

Abstract

The arc-extinguishing device has a first (16) and second (19) exhausting passages for exhausting gas generated by the arc. The second exhausting passage (19) improves the smooth flow of the gas. The device may be used in a circuit breaker and be provided with arc runners (17, 18) and an arc-dividing grid unit (12). <IMAGE>

Description

SPECIFICATION Arc-extinguishing device 1. FIELD OF THE INVENTION This invention relates to arc-extinguishing device.

2. DESCRIPTION OF THE RELATED ART Published unexamined patent application SH055-46487 discloses an arc-extinguishing device used in a circuit breaker as shown in Fig. 1. Under overload or short circuit conditions, the circuit breaker opens the circuit by disconnecting the movable contact 7 from the fixed contact 5. At this time, an arc is produced between the contacts 5 and 7, and runs on arc runners 17, 18. The arc is moved to a grid unit 12 by known magnetic force, and is divided and suppressed. Gag generated by the arc is exhausted from an arc-extinguishing Chamber 10 to outside, through exhausting holes of an end plate 15 and an exhausting passage 16. The exhausting holes 15a are provided on the end plate 15 as shown in Fig. 2.

The known device mentioned above fails to make smooth exhausting of the gas, thereby resulting in a slowed arc running. The slowed arc running reduces the current limiting characteristic as shown in Fig. 3, because the slowed arc running slows the division in the grid unit 12 and suppression of the arc.

SUMMARY OF THE INVENTION A pressure-responsive apparatus in accordance with the present invention comprises: a pair of arc runners for making running of an arc made between two contacts, grid unit provided between the arc runners for dividing and suppressing the arc, a first exhausting passage for exhausting a part of gas generated by the arc, and a second exhausting passage for exhausting rest part of gas generated by the arc.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is the cross-sectional side view of the conventional arc-extinguishing device.

Figure 2 shows the end plate used in the arc-extinguishing device of Fig. 1.

Figure 3 is the graph for showing the arc voltage-let through current characteristic.

Figure 4 is a cross-sectional side view of an embodiment of an arc-extinguishing device embodying the present invention.

Figure 5 is a graph for showing an arc voltage-let through current characteristic.

Figure 6 is a cross-sectional side view of another embodiment of an arc-extinguishing device having a separation plate.

Figures 7A and 7B are cross-sectional side view of still other embodiments of an arcextinguishing device having guide plates.

Figure 8 is a cross-sectional side view of further embodiment of an arc-extinguishing device having a projection.

Figure 9 is a sectional view taken on line ll-ll of Fig. 8.

Figure 10 is a cross-sectional side view of another embodiment of an arc-extinguishing device.

DETAILED DESCRIPTION OF PREFERRED EM BODIMENTS The structure of a preferred embodiment of an arc-extinguishing device embodying the present invention is described in detail with reference to Fig. 4. A circuit breaker 100 comprises a molded insulating housing 1 in which a circuit breaker mechanism is provided.

The circuit breaker mechanism comprises a fixed contact 5, a movable contact 7, a magnetic tripping device 8A, an operating mechanism 8B, an upper arc-runner 17, a lower arc runner 18, a grid unit 12, an end plate 15 and a first exhausting passage 16, which are of known configuration and function. The mechanism further has an exhausting vent 19 as a second exhausting passage. Under overload or short circuit conditions, the known magnetic tripping device 8A detects an occurrence thereof and opens the circuit by disconnecting the movable contact 7 from the fixed contact 5. At this time, an arc occurs between the contacts 5 and 7, and runs between arc runners 17, 18. The arc moves to the grid unit 12 by known magnetic force, and is divided and suppressed by stacked grids 13 of the grid unit 12.Gas generated by the arc is exhausted from an arc-extinguishing Chamber 11 through the exhausting hole of the end plate 15. A part of the gas from the arc-extinguishing Chamber 11 is exhausted to outside of the circuit breaker 100, through the first exhausting passage 16 and the first exhausting outlets 16A. Other part of the gas from the arcextinguishing Chamber 11 is exhausted to the outside of the circuit breaker 100 through the exhausting vent 19 and the second exhausting outlets 19A.

In the present invention, because the gas is exhausted both through the first and second exhausting passage, the gas is smoothly exhausted. Therefore, the gas pressure in the arc-extinguishing Chamber 11 does not be come high, thereby enabling a smooth arc run ning. The smooth arc running makes an excel lent current limiting characteristic, because the smooth arc running enables quick division and suppression of the arc.

Fig. 5 shows the arc voltage-let through current characteristic of the circuit breaker show in Fig. 4. The arc voltage more smoothly rises up than prior device as shown in Fig. 5.

Fig. 6 is a cross-sectional side view of another embodiment of arc-extinguishing de vice. In this embodiment, a separation plate 20 is provided between the first exhausting passage 16 and the exhausting bent 19.

Therefore, an upper part of the gas flows only to the first exhausting passage 16 and a lower part of gas flows only to the exhausting vent 19, without making interference to each other. Therefore, the gas smoothly flows thereby enabling smooth arc running and extinguishing.

Figs. 7A and 7B are cross-sectional side view of still other embodiments of an arcextinguishing device. In these embodiments, the guide vanes 30 formed in the circular arc shape are provided in a vent part. The guide vanes 30 make smooth flow of the gas, thereby enabling smooth arc running.

Fig. 8 is a cross-sectional side view of further other embodiment of an arc-extinguishing device. In this embodiment, a stream smoothing protrusion 40 is formed in the vent part 19a of the exhausting vent 19 for forming a portion 1 9b of lower height and greater width part than other parts of the vent 19. Fig. 9 is a sectional view taken on line ll-il of Fig. 8.

As shown in Fig. 9, the width D1 of the part 1 9b is wider than the width D2 of adjacent other parts. The lower height and greater width part 1 9b makes the flow of the gas smooth thereby enabling smooth arc running.

Fig. 10 is a cross-sectional side view of another embodiment of an arc-extinguishing device. In this embodiment, the protrusion 40 is formed by folding an end of the arc-runner 18.

As has been described in detail for various embodiments, the arc-extinguishing device in accordance with the present invention provides good current limiting characteristic, as a result of introducing the second exhausting passage 19.

Claims

1. Arc-extinguishing device comprising: a pair of arc runners and making runing of an arc made between two contacts, grid unit provided between the arc runners for dividing and suppressing the arc, a first exhausting passage for exhausting a first part of the gas generated by the arc, and a second exhausting passage for exhausting a second part of the gas generated by the arc.

2. Arc-extinguishing device in accordance with claim 1, further comprising a separation plate for separating said exhausting passages to prevent interference between flows of the gas.

3. Arc-extinguishing device in accordance with claim 1 or 2 wherein the first exhausting passage has flow guide vanes adjacent its vent part.

4. Arc-extinguishing device in accordance with claim 1, 2 or 3 wherein the second exhausting passage has flow guide vanes therein.

5. Arc-extinguishing device in accordance with claim 1, 2, 3 or 4 wherein the first exhausting passage has a portion of lower height and greater width than other parts of the passage.

8. Arc-extinguishing device in accordance with claim 1, wherein the second exhausting passage has a portion of lower height and greater width than other parts of the passage.

7. Arc-extinguishing device in accordance with claim 5 or 6, wherein the said portion of a lower height and greater width includes a projection in the passage.

8. Arc-extinguishing device in accordane with claim 7 wherein the projection is formed by a folded end part of an arc-runner.

9. An arc-extinguishing device substantially as hereinbefore described with reference to Fig. 4, 6, 7A, 7B, or 10; or to Figs. 8 and 9 of the accompanying drawings.

10. A circuit breaker comprising a device according to any preceding claim.