GB1594487A - Gas blast switches and circuit interrupters - Google Patents
Gas blast switches and circuit interrupters Download PDFInfo
- Publication number
- GB1594487A GB1594487A GB4962877A GB4962877A GB1594487A GB 1594487 A GB1594487 A GB 1594487A GB 4962877 A GB4962877 A GB 4962877A GB 4962877 A GB4962877 A GB 4962877A GB 1594487 A GB1594487 A GB 1594487A
- Authority
- GB
- United Kingdom
- Prior art keywords
- contact
- gas
- contacts
- cylinder
- circuit breaker
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H33/00—High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
- H01H33/70—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid
- H01H33/7015—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts
- H01H33/7084—Switches with separate means for directing, obtaining, or increasing flow of arc-extinguishing fluid characterised by flow directing elements associated with contacts characterised by movable parts influencing the gas flow
Landscapes
- Circuit Breakers (AREA)
Description
(54) IMPROVEMENTS IN OR RELATING TO GAS BLAST
SWITCHES AND CIRCUIT INTERRUPTERS
(71) We, ASSOCIATED ELEC TRICAL INDUSTRIES LIMITED, of 1,
Stanhope Gate, London W1A 1EH, a British
Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to gas blast switches and circuit breakers of the kind incorporating, within a gas-filled chamber, a pair of contacts at least one of which is movable between a closed position in which it engages the other contact, and an open position in which the contacts are spaced from each other, at least one of the contacts beng of tubular form, and means being provided for producing a rapid flow of gas into the region between the contact making faces of the contacts and through the tubular contact or contacts when the contacts are separated.
Circuit interruption in such devices normally takes place by drawing an arc between the contacts, and the blast of relatively high pressure gas through the tubular contact or contacts as the contacts separate has the effect of containing the arc and sweeping the arc products through the or each said tubular contact into a relatively low pressure downstream region. Usually the arc will extinguish at approximately current zero, the rapid build up of dielectric strength in the region between the contacts being such as to withstand the recovery voltage.
However when interrupting low current arcs, typically of the order of 10 to 20 amps, the blast of gas can force the current to a premature zero, and where the current being broken is predominantly inductive the energy stored in the circuit can appear at the circuit braker terminal as an overvoltage, the magnitude of which will depend upon the instantaneous value of the current "chopped" and on the values of the circuit constants, and can in some cases be considerable.
This is clearly undesirable, and an object of the invention is to provide a form of gas
blast switch or circuit breaker in which this
difficulty is alleviated.
According, therefore, to one aspect of the
invention a gas-blast switch or circuit breaker
of the kind referred to incorporates, within the contact making end of a said tubular contact, a baffle means formed of electrically conducting
material and electrically connected to the contact, said baffle means having the form of a
disc having a plurality of radially extending
segments each set at an angle in the manner
of an axial flow fan blade.
It has been found that the presence of the
baffle means, and the consequent change in
direction of the gas, encourages any arc that
is formed to root on the baffle itself, or
alternatively on an adjacent part of the contact.
In this way a short and relatively stable arc
is formed, which tends to extinguish at
approximately current zero, the production
of a relatively long unstable arc rooting at or
near the opposite end of the contact, and
which tends to "chop" at a higher level of
current, being substantially avoided.
The degree of deflection of the gas flow
giving the most satisfactory results for any
particular form of gas-blast switch or circuit
breaker in accordance with the invention, and
the form of baffle means for producing such
deflection, may readily be found by trial.
The disc segments break up the flow of gas
and produce a swirling movement. The indi
vidual segments may overlap each other, al
though in general this will not be necessary.
Usually the tubular contact will have a bore
of circular cross section, the disc preferably
extending across the full width of the bore.
In a modification of this arrangement the
disc may be rotatably mounted within the
hollow contact; then as the gas-blast passes
through the contact, as the contacts separate,
the gas impinging on the inclined segments,
will not only be caused to swirl, but will also
rotate the disc, causing the segments to sweep
around the bore of the contact. This will
assist the arc to root on the disc or an adjacent
part of the contact.
According, therefore, to another aspect of the invention a gas-blast switch or circuit breaker of the kind referred to incorporates, within the contact making end of the tubular contact, a member which extends across substantially the whole of the bore of the contact and is mounted for rotation about the bore axis, the member comprising a plurality of segments extending radially from a hub portion and having operative faces so inclined that the flow of-gas through the contact as the contacts separate acts on the operative faces of the segments to produce a rotation of the member.
The baffle means of a gas-blast switch or circuit breaker in accordance with the invention may incorporate two or more axially spaced members, which can be either fixed or rotatable, and other forms of baffle means could alternatively be employed.
Usually the movable contact will be of tubular form, and incorporate the said baffle means. However the other contact may also be of tubular form, through which a flow of gas is arranged to take place when the contacts separate, and in such a case the bore of this contact may also be provided with a said baffle means adjacent the contact making end of the contact.
This other contact may be fixed in position within the contact chamber or it may be biassed axially towards a rest position from which it is displaced by the movable contact when engaged by the-latter in order to ensure good electrical contact between them in the closed condition, the said other contact then following the movable contact for a short distance when the latter is moved to the open position.
In yet another form of switch or circuit breaker both contacts may be arranged to be movable away from each other into the contact open position.
Any suitable means may be provided for producing a blast of gas through the tubular contact or contacts during separation. Thus means may be provided for producing an increase in the pressure of the gas in the region between the contacts, compared with the normal pressure within the chamber as the movable contact moves from the closed to the open position. Alternatively or additionally the switch or circuit breaker may incorporate means for creating a region of reduced pressure, compared with the normal pressure within the chamber, on movement of the movable contact from the closed to the open position, and means for connecting the interior of the movable contact to said reduced pressure region to cause gas from the chamber to expand through the contact as the contacts separate. For example a piston coupled to the movable contact so as to move with it may be used to compress the gas within a cylinder communicating with the region between the contacts so as to increase the gas pressure in said region, compared with that at the outer end of the contact or contacts, as the contacts separate. A reduction in the pressure at the outer end of the or each tubular contact may be similarly achieved under the action of a piston movable within a cylinder, to cause the gas within the main contact space to expand rapidly through the tubular contact or contacts into the cylinder during contact separation. An increase in pressure in the region between the contacts, and/or a reduction in the pressure at the outer end of the or each tubular contact, as the contacts separate can alternatively be produced by a cylinder movable with respect to a fixed position piston.
The invention will now be further explained by reference to Figures 1 to 4 of the accompanying schematic drawings in which,
Figure 1 illustrates diagrammatically a sectional view of the contacts of a typical form of circuit breaker,
Figure 2 illustrates diagrammatically a sectional view of the contacts of a circuit breaker in accordance with the present invention,
Figure 3 illustrates a perspective view of part of one of the contacts, and
Figure 4 illustrates an arrangement for producing a blast of gas through the contacts as the contacts separate.
Referring first to Figure 1 of the drawing, this illustrates in diagrammatic form a pair of contacts 1,2 of a known form of gas-blast circuit breaker, the contacts being enclosed within a housing (not shown) containing an arc suppressing gas such as SF,. Both contacts are of hollow tubular form disposed in alignment with each other, the contact 1 being movable axially between a closed position in which it engages the contact 2, and an open position in which it is spaced therefrom. The adjacent or contact making ends of both contacts 1,2 are in the form of nozzles 3 as shown.
In normal operation, an arc is formed between the contacts when they are opened to interrupt a large current. At the same time gas from the main part of the housing surrounding the contact-making ends of contacts, and at a relatively high pressure, is caused to flow rapidly inwards into the arc gap and then through the contacts to regions of relatively low pressure, the blast of gas containing the arc and causing it to extinguish at current zero.
Upon certain operating conditions, however, and depending upon the circuit being broken, the blast of gas can force the current to a premature zero, with the energy stored in the circuit appearing as an overvoltage at the breaker terminal.
Thus the interruption of a relatively low current can, in some cases, give rise to the production of a small diameter arc which, instead of rooting on or adjacent the contact making ends of the contacts, is carried into either one or both of the contacts and roots at the outer end or ends thereof. The arc 4 can in some cases also coil back on itself as shown at 4a. Such a long, small-diameter arc is inherently unstable and thus tends to "chop" at a higher current level than a shorter more stable arc.
In an arrangement in accordance with the present invention a baffle 5 is fitted into each of the hollow contacts 1,2 near to the contact nozzles 3 as shown in Figure 2. The effect of this is to produce a distortion in the flow of gas through the contacts in the regions of the contact nozzles 3 as the contacts are opened, and thus encourages the arc to root either on the baffles, where these are of conducting material, or adjacent parts of the contacts.
Accordingly the length of the arc will be reduced.
Each baffle is conveniently in the form of a metal disc 5a formed with a plurality of segments 6 extending radially outwards from a hub portion 7, and set at an angle in the manner of fan blades, as shown more clearly in Figure 3, which represents a perspective view of the nozzle end of the movable contact.
In this case the disc within the contact 1 is shown mounted for rotation on a probe 8 disposed centrally within the contact 1 the segments extending nearly to the wall of the contact. Then as the gas blast passes into the nozzle 3 and through the contact, during the opening movement of the contact, the disc will start to rotate and the segments 6 will sweep an area of the contact bore through which the arc might otherwise pass, and this assists the arc to root on the disc itself, the central probe 8 or an adjacent part of the wall of the contact 1. The baffle 5 within the other contact 2 can also be formed as a similar rotatable segmented disc. Although the segments 6 are shown with spaces between them they can in some cases be arranged to overlap.
Moreover the discs 5a need not necessarily rotate, and provided they are constructed to provide an adequate deflection of the gas path they may be fixed in position.
It will also be appreciated that other shapes of disc can alternatively be employed if desired.
The discs 5a of the circuit breaker described can in some cases be insulated from the respective contacts, or may themselves be of insulating material, the arc then being caused to root either on the respective probe 8 or on the surrounding wall of the contact.
A contact arrangement for producing a blast of gas through both contacts 1,2 as they separate is illustrated in diagrammatic form in Figure 4.
In this arrangement the movable contact 1 is coaxially sunrrounded by a cylinder 11 of insulating material carried by a flange 12 extending radially from the outer end of the
contact, so that the cylinder moves with the
contact. The cylinder 11 extends from the flange in the direction of the other contact 2
so as to surround the adjacent end of the latter
in the contact closed position, the wall 10 at
the free end of the cylinder being turned
inwards so as to terminate closely adjacent
the wall of this contact 2. Within the cylinder
11 lies an annular piston 13 supported by
rods 14 extending through openings 15 in the
flange 12 and fixed to a suitable support (not
shown). Ports 16 in the wall of the contact 1
connect the interior of the contact to the end
of the cylinder lying between the flange 12
and the piston 13. As the contact 2 moves from
the closed position shown on the left of the
Figure to the open position shown on the right
of the Figure, the pressure of gas in the upper
part of the cylinder 11 (in the position shown)
will increase and that in the lower part of the
cylinder will be reduced thereby producing a pressure differential between the ends of the
contact 1, and causing gas to expand outwards
through the contact as the contacts separate.
The other contact 2 is provided, at its outer
end, with a radially outwardly directed flange
17, which constitutes a piston movable within
a surrounding cylinder 18, the contact being
biassed towards the movable contact 1 by a
spring 19. In the closed position of the contacts,
the contact 2 is displaced backwards against
the spring bias by the movable contact 1. Then
when the latter moves towards the open
position the contact 2 follows it for a short
distance. This results in a region of reduced
pressure being developed within the outer end
of the cylinder 18 which communicates with
the interior of the contact 2, thereby resulting
in a difference in pressure between the inner
and outer ends of the contact causing a blast of gas to flow through it as the contacts separate.
It will, however, be understood that other ways of producing blasts of gas through one or both contacts as the contacts separate, can alternatively be used if desired.
The invention is of a particular advantage in gas blast switches and circuit breakers arranged to interrupt the current through transformer windings, electric motors and other predominantly inductive loads, where premature current chopping could result in considerable overvoltages.
WHAT WE CLAIM IS:
1. A gas-blast switch or circuit breaker of the kind referred to incorporating within the contact, making end of a said tubular contact, a baffle means formed of electrically conducting material and electrically connected to the contact wherein the baffle is in the form of a disc having a plurality of radially extending segments each set at an angle in the manner of an axial flow fan blade.
2. A gas-blast switch or circuit breaker
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (15)
- **WARNING** start of CLMS field may overlap end of DESC **.instead of rooting on or adjacent the contact making ends of the contacts, is carried into either one or both of the contacts and roots at the outer end or ends thereof. The arc 4 can in some cases also coil back on itself as shown at 4a. Such a long, small-diameter arc is inherently unstable and thus tends to "chop" at a higher current level than a shorter more stable arc.In an arrangement in accordance with the present invention a baffle 5 is fitted into each of the hollow contacts 1,2 near to the contact nozzles 3 as shown in Figure 2. The effect of this is to produce a distortion in the flow of gas through the contacts in the regions of the contact nozzles 3 as the contacts are opened, and thus encourages the arc to root either on the baffles, where these are of conducting material, or adjacent parts of the contacts.Accordingly the length of the arc will be reduced.Each baffle is conveniently in the form of a metal disc 5a formed with a plurality of segments 6 extending radially outwards from a hub portion 7, and set at an angle in the manner of fan blades, as shown more clearly in Figure 3, which represents a perspective view of the nozzle end of the movable contact.In this case the disc within the contact 1 is shown mounted for rotation on a probe 8 disposed centrally within the contact 1 the segments extending nearly to the wall of the contact. Then as the gas blast passes into the nozzle 3 and through the contact, during the opening movement of the contact, the disc will start to rotate and the segments 6 will sweep an area of the contact bore through which the arc might otherwise pass, and this assists the arc to root on the disc itself, the central probe 8 or an adjacent part of the wall of the contact 1. The baffle 5 within the other contact 2 can also be formed as a similar rotatable segmented disc. Although the segments 6 are shown with spaces between them they can in some cases be arranged to overlap.Moreover the discs 5a need not necessarily rotate, and provided they are constructed to provide an adequate deflection of the gas path they may be fixed in position.It will also be appreciated that other shapes of disc can alternatively be employed if desired.The discs 5a of the circuit breaker described can in some cases be insulated from the respective contacts, or may themselves be of insulating material, the arc then being caused to root either on the respective probe 8 or on the surrounding wall of the contact.A contact arrangement for producing a blast of gas through both contacts 1,2 as they separate is illustrated in diagrammatic form in Figure 4.In this arrangement the movable contact 1 is coaxially sunrrounded by a cylinder 11 of insulating material carried by a flange 12 extending radially from the outer end of the contact, so that the cylinder moves with the contact. The cylinder 11 extends from the flange in the direction of the other contact 2 so as to surround the adjacent end of the latter in the contact closed position, the wall 10 at the free end of the cylinder being turned inwards so as to terminate closely adjacent the wall of this contact 2. Within the cylinder11 lies an annular piston 13 supported by rods 14 extending through openings 15 in the flange 12 and fixed to a suitable support (not shown). Ports 16 in the wall of the contact 1 connect the interior of the contact to the end of the cylinder lying between the flange 12 and the piston 13. As the contact 2 moves from the closed position shown on the left of the Figure to the open position shown on the right of the Figure, the pressure of gas in the upper part of the cylinder 11 (in the position shown) will increase and that in the lower part of the cylinder will be reduced thereby producing a pressure differential between the ends of the contact 1, and causing gas to expand outwards through the contact as the contacts separate.The other contact 2 is provided, at its outer end, with a radially outwardly directed flange 17, which constitutes a piston movable within a surrounding cylinder 18, the contact being biassed towards the movable contact 1 by a spring 19. In the closed position of the contacts, the contact 2 is displaced backwards against the spring bias by the movable contact 1. Then when the latter moves towards the open position the contact 2 follows it for a short distance. This results in a region of reduced pressure being developed within the outer end of the cylinder 18 which communicates with the interior of the contact 2, thereby resulting in a difference in pressure between the inner and outer ends of the contact causing a blast of gas to flow through it as the contacts separate.It will, however, be understood that other ways of producing blasts of gas through one or both contacts as the contacts separate, can alternatively be used if desired.The invention is of a particular advantage in gas blast switches and circuit breakers arranged to interrupt the current through transformer windings, electric motors and other predominantly inductive loads, where premature current chopping could result in considerable overvoltages.WHAT WE CLAIM IS: 1. A gas-blast switch or circuit breaker of the kind referred to incorporating within the contact, making end of a said tubular contact, a baffle means formed of electrically conducting material and electrically connected to the contact wherein the baffle is in the form of a disc having a plurality of radially extending segments each set at an angle in the manner of an axial flow fan blade.
- 2. A gas-blast switch or circuit breakeraccording to Claim 1 wherein the disc is mounted for rotation about the axis of the tubular contact.
- 3. A gas-blast switch or circuit breaker according to any preceding claim wherein the baffle means comprises two or more axially spaced members.
- 4. A gas-blast switch or circuit breaker of the kind referred to incorporating within the contact making end of the tubular contact, a member which extends across substantially the whole of the bore of the contact and is mounted for rotation about the bore axis, the member comprising a plurality of segments extending radially from a hub portion and having operative faces so inclined that the flow of gas through the contact as the contacts separate acts on the operative faces of the segments to produce a rotation of the member.
- 5. A gas-blast switch or circuit breaker according to any preceding claim wherein the said tubular contact containing the baffle means or the rotatable member, as the case may be, is a contact which is movable between a closed position in which it engages the other contact and an open position in which the contacts are spaced from each other.
- 6. A gas-blast switch or circuit breaker according to Claim 5 wherein said other contact is also of tubular form, through which a flow of gas is arranged to take place when the contacts separate, wherein this other contact also accommodates, near its contact making end, a baffle means arranged to produce a deflection of gas passing through the contact during contact separation.
- 7. A gas-blast switch or circuit breaker according to Claim 6 wherein the baffle means in both the contacts are mounted for rotation within the bores of the respective contacts.
- 8. A gas-blast switch or circuit breaker, according to Claim 6 or 7 wherein said other contact is biassed axially towards a rest position from which it is displaced by the movable contact when engaged by the latter in the closed position, the other contact following the movable contact for a short distance when the latter is moved towards the open position.
- 9. A gas-blast switch or circuit breaker according to any one of Claims 5 to 8 incorporating means for producing an increase in the pressure of the gas in the region between the contacts, compared with the normal pressure within the chamber as the movable contact moves from the closed to the open position.
- 10. A gas-blast switch or circuit breaker according to any one of Claims 5 to 9 including means for creating a region of reduced pressure, compared with the normal pressure within the chamber, on movement of the movable contact from the closed to the open position, and means for connecting the interior of the movable contact to said reduced pressure region to cause gas from the chamber to expand through the contact as the contacts separate.
- 11. A gas-blast switch or circuit breaker according to Claim 9 incorporating a piston accommodated within a cylinder which communicates with the region between the contacts, the piston being coupled to, so as to move with, the movable contact and arranged to produce an increase in the gas pressure in the cylinder, and hence in said region, compared with that at the outer end of the tubular contact or contacts, as the contacts separate.
- 12. A gas-blast switch or circuit breaker according to 'Claim 10 incorporating a piston accommodated within a cylinder, and coupled to the movable contact so that as the contact moves from the closed towards the open position a region of reduced pressure is created within the cylinder, the interior of the contact communicating with the reduced pressure region of the cylinder so as to cause gas to flow from the contact chamber to expand through the contact as the contacts separate.
- 13. A gas-blast switch or circuit breaker according to Claim 9 incorporating a cylinder coupled to, so as to move with, the movable contact, and accommodating a piston fixed in position relative to said chamber such that as the contact moves from the closed towards the open position the pressure of gas within the cylinder is increased, the cylinder communicating with the region between the contacts so as to produce an increase in the pressure in said region as the contacts separate.
- 14. A gas-blast switch or circuit breaker according to Claim 10 incorporating a cylinder coupled to, so as to move with, the movable contact, and accommodating a piston fixed in position relative to said chamber such that as the contact moves from the closed towards the open position the pressure of gas within the cylinder is reduced, the interior of the contact communicating with the reduced pressure region of the cylinder so as to cause gas from the contact chamber to expand through the contact as the contacts separate.
- 15. A gas-blast switch or circuit breaker of the kind referred to incorporating a contact arrangement substantially as shown in and as hereinbefore described with reference to Figure 2, 3 or 4 of the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB4962877A GB1594487A (en) | 1978-05-23 | 1978-05-23 | Gas blast switches and circuit interrupters |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB4962877A GB1594487A (en) | 1978-05-23 | 1978-05-23 | Gas blast switches and circuit interrupters |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1594487A true GB1594487A (en) | 1981-07-30 |
Family
ID=10453005
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB4962877A Expired GB1594487A (en) | 1978-05-23 | 1978-05-23 | Gas blast switches and circuit interrupters |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1594487A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7893379B2 (en) | 2004-12-24 | 2011-02-22 | Abb Technology Ag | Generator circuit breaker with improved switching capacity |
| FR2954995A1 (en) * | 2010-01-04 | 2011-07-08 | Areva T & D Sas | Average, high or very-high voltage gas circuit-breaker e.g. puffer circuit breaker, has rotating device placed concentrically around longitudinal axis of circuit-breaker and placed in rod side exhaust volume and socket side exhaust volume |
| CN114062746A (en) * | 2021-11-23 | 2022-02-18 | 江苏欧达电气有限公司 | Breakdown-preventing intelligent ammeter box |
-
1978
- 1978-05-23 GB GB4962877A patent/GB1594487A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7893379B2 (en) | 2004-12-24 | 2011-02-22 | Abb Technology Ag | Generator circuit breaker with improved switching capacity |
| EP1829077B2 (en) † | 2004-12-24 | 2011-03-23 | ABB Technology AG | Generator switch having an improved switching capacity |
| FR2954995A1 (en) * | 2010-01-04 | 2011-07-08 | Areva T & D Sas | Average, high or very-high voltage gas circuit-breaker e.g. puffer circuit breaker, has rotating device placed concentrically around longitudinal axis of circuit-breaker and placed in rod side exhaust volume and socket side exhaust volume |
| CN114062746A (en) * | 2021-11-23 | 2022-02-18 | 江苏欧达电气有限公司 | Breakdown-preventing intelligent ammeter box |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |