GB2511373A - Improvements relating to vacuum switching devices - Google Patents

Improvements relating to vacuum switching devices Download PDF

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Publication number
GB2511373A
GB2511373A GB1318392.6A GB201318392A GB2511373A GB 2511373 A GB2511373 A GB 2511373A GB 201318392 A GB201318392 A GB 201318392A GB 2511373 A GB2511373 A GB 2511373A
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GB
United Kingdom
Prior art keywords
arms
coil assembly
contact
vacuum switching
switching device
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.)
Granted
Application number
GB1318392.6A
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GB2511373B (en
GB201318392D0 (en
Inventor
Leslie Thomas Falkingham
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co PLC
Original Assignee
General Electric Co PLC
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Filing date
Publication date
Application filed by General Electric Co PLC filed Critical General Electric Co PLC
Publication of GB201318392D0 publication Critical patent/GB201318392D0/en
Publication of GB2511373A publication Critical patent/GB2511373A/en
Application granted granted Critical
Publication of GB2511373B publication Critical patent/GB2511373B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01HELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H33/00High-tension or heavy-current switches with arc-extinguishing or arc-preventing means
    • H01H33/60Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid
    • H01H33/66Vacuum switches
    • H01H33/664Contacts; Arc-extinguishing means, e.g. arcing rings
    • H01H33/6644Contacts; Arc-extinguishing means, e.g. arcing rings having coil-like electrical connections between contact rod and the proper contact

Landscapes

  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)

Abstract

A vacuum switching device comprises an evacuated envelope having an insulator; a fixed electrode and a moving electrode which engage and disengage mechanically to perform switching and which include a contact of the axial field type comprising a coil assembly behind a contact disc. The coil assembly has between one and five arms which follow a curved path from a centre electrode to the outer diameter of the contact disc. The curved arms may be formed of successive circular arcs, be of constant width and have a constant separation from their neighbours. The coil can have two, three or four arms whose spiral path covers between 200, 130, 100 and 80 degrees of rotation respectively. The coil assembly can have radiused corners and edges to improve the voltage performance. The coil provides self-generated axial magnetic fields in the axis of the contact gap in order to make an arc diffuse over the contact surface at high currents.

Description

Improvements Relating To Vacuum Switching Devices
Description
This invention relates to improvements in vacuum switching devices, which may include for example vacuum interrupters or vacuum switches.
A simplified schematic diagram of a typical vacuum switching device is shown in figure 1. Vacuum switching devices generally consist of an evacuated envdope, which includes an insulating component (a), a fIxed electrode assembly tb), and a moving electrode assembly tIc). The electrodes consist of a conducting rod (d) and a contact assembly (e). The two contact assemblies include contact discs (f). The electrodes are designed to engage and disengage mechanically to perform the switching function. This movement is permitted without breaking the seal of the evacuated envelope by means of a bellows or diaphragm arrangement (g). Dunng switching an arc of electric cuiTent passes from one contact disc to the other. At low currents the arc is diffuse, that is, spread over the contact surfaces. Above a current of a few thousands of amps, due to aspects of the physics of the vacuum arc, the arc tends to constrict into a narrow column. This can cause overheating of pafts of the contact surfaces, which limits the level of current which can be successfully interrupted.
Vacuum switching devices that are designed to switch large culTents have been produced for many years. A number of different designs of electrode assemblies have been proposed for use under high current conditions, These designs use self-generated magnetic fields to control the arcs. The prior art falls into two categories, which work in different ways. In one category the contact geometry produces a radial magnetic field; in the other category the contact geometry produces an axial magnetic field. With radial magnetic field geometries the contact faces are generally in the form of annular rings, not discs, and a constricted arc is driven by the radia' magnetic field to continuously move around the ring, so that excessive heating is not produced at any one point. Examples are EP0525354 Al and US4553002 A. With axial magnetic field geometries the contact faces are generally in the form of discs, and the effect of the axial field is to diffuse the current arc fairly evenly over the contact surfaces, thereby preventing overheating of these surfaces. Examples of such designs may be seen in EP 0349303, DR 3915519, DR 3610241. GB 2381 1 IA. This invention concerns only
axial field contact assemblies.
Figure 2 shows construction features common to some of these axial arc electrode assemblies. The conducting rod (d) carries current to arm conductors (h) that cariy current via pillars (i) to the contact disc (I). Current is then carried across the vacuum to the other electrode disc by one or more arcs (j). The arm conductors of the two contact assemblies are arranged so that current circulates in the same sense in both arm conductors. The configuration of current flow produces a desired configuration of magnetic field which is generally in the axial direction of the contacts in the space between the contact discs and this magnetic field prevents constriction of the arcs.
The arm conductor assemblies are also known as coil assemblies.
This invention relates to one particular type of prior art contact geometry as typified by US 39946179. Figure 3 shows an exploded view of this geometry. The culTent path in the coil tIh) is radial from the centre to the penphery of the contact at which point it turns to follow the curve of the outside diameter of the contact disc. The design of coil assembly in US 39946179 is shown in plan view in figure 4.
This prior art geometry gives an axial magnetic field which is essentially concentrated at the outside diameter of the contact disc, which has the disadvantage that it gives a lower field at the inner part of the contact disc. It also gives rise to eddy currents in the contact disc, which, to one skilled in the art, is known to be detrimental to the generation of the axial magnetic field, reducing its effectiveness locally.
According to the invention, an embodiment of which is shown in figure 5. the coil assembfies each include curved arm conductors to provide the path along which the cunent flows. In this case the current path from the rod to the contact disc follows a curved path which gives additional axial magnetic field strength at the inner part of the contact disc and also reduces the eddy culTent effects, thereby improving the arc control capability of the contact assembly. Because this invention allows the current to follow a longer path than previous'y it also increases the overall strength of the axial magnetic field due to an increase in the effective number of coil turns for each contact arm.
This invention both improves the strength of the axial magnetic field generated and spreads the magnetic field over a larger surface area of the contact disc with a result that a higher current can be successfully interrupted for a given size of contact diameter, thereby making the vacuum switching device smaller and of lower cost.
An additional benefit of the invention is that the use of curved arms, as opposed to arms which include a sharp change in direction, significantly reduces electrostatic stress fields and thereby provides improved voltage performance for the vacuum switching device which is particubrly advantageous for high voliage applications.
In one form of the curved arms, illustrated in figure 5 for the case of four arms, the main part of the curve of each aim consists of successive sections of circular arc, the inner and outer radii of each section being of constant difference to yield a constant width of arm, and the radii and centres of successive sections being chosen to keep the gaps between each arm and its neighbours constant.
The invention may be applied to the design of vacuum switching devices over a wide range of contact diameters, the actual diameter chosen depending to a great extent on the intended maximum current to be interrupted, and the maximum load current intended to be canied.
A person skilled in the art will appreciate that this invention may be applied to variations of this basic geometry from one arm to many arms.

Claims (8)

  1. Claims: A vacuum switching device consisting of an evacuated envelope which includes an insulating component, a fixed electrode and a moving electrode which are designed to engage and disengage mechanically to perform the switching function and which includes at least one contact of the axial field type with a coil assembly behind a contact disc whereby the coil assembly has between one arm and five arms and the arms follow a curved path from the centre electrode to approximately the outside diameter of the contact disc.
  2. 2. A vacuum switching device consisting of an evacuated envelope which includes an insulating component, a fixed electrode and a moving electrode which are designed to engage and disengage mechanically to perform the switching function and which includes at least one contact of the axial field type with a coil assembly behind a contact disc whereby the coil assembly has between one arm and five arms and the arms follow a curved path from the centre electrode to approximately the outside diameter of the contact disc, and the main parts of the curved arms are formed of successive circular arcs.
  3. 3. A vacuum switching device consisting of an evacuated envelope which indudes an insulating component, a fixed electrode and a moving electrode which are designed to engage and disengage mechanically to perform the switching function and which includes at least one contact of the axial field type with a coil assemhly behind a contact disc whereby the coil assembly has between one arm and five arms and the arms follow a curved path from the centre electrode to approximately the outside diameter of the contact disc, and the main parts of the curved arms are formed of successive circular arcs, and are of constant width and have constant separation from their neighbours.
  4. 4. A vacuum switching device as described in Claims 1, 2 or 3 whereby the coil assembly has two arms and the spiral path covers more than 2000 of rotation.
  5. 5. A vacuum switching device as described in Claims 1, 2 or 3 whereby the coil assembly has three arms and the spiral path covers more than i30° of rotation.
  6. 6. A vacuum switching devicc as described in Claims 1, 2 or 3 whereby the coil assembly has four arms and the spiral path covers more than 100° of rotation.
  7. 7. A vacuum switching device as described in Claims 1, 2 or 3 whereby the coil assembly has five arms and the spiral path covers more than 80° of rotation.
  8. 8. A vacuum switching device as described in claims 1, 2 or 3 whereby the coil assembly has radiused corners and edges to improve voltage performance.
GB1318392.6A 2012-10-23 2013-10-17 Vacuum switching device having axial field contacts Active GB2511373B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1218975.9A GB2507262A (en) 2012-10-23 2012-10-23 Spiral contact coil for vacuum switch

Publications (3)

Publication Number Publication Date
GB201318392D0 GB201318392D0 (en) 2013-12-04
GB2511373A true GB2511373A (en) 2014-09-03
GB2511373B GB2511373B (en) 2018-01-03

Family

ID=47359290

Family Applications (2)

Application Number Title Priority Date Filing Date
GB1218975.9A Withdrawn GB2507262A (en) 2012-10-23 2012-10-23 Spiral contact coil for vacuum switch
GB1318392.6A Active GB2511373B (en) 2012-10-23 2013-10-17 Vacuum switching device having axial field contacts

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB1218975.9A Withdrawn GB2507262A (en) 2012-10-23 2012-10-23 Spiral contact coil for vacuum switch

Country Status (1)

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GB (2) GB2507262A (en)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1478702A (en) * 1973-09-10 1977-07-06 Tokyo Shibaura Electric Co Vacuum interrupter
DE3112407A1 (en) * 1981-03-28 1982-04-08 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Switching contact for vacuum switches
DE3107155A1 (en) * 1981-02-26 1982-09-09 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Vacuum switch
DE3130466A1 (en) * 1981-07-23 1983-02-17 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Contact for a vacuum switch
DE3338254A1 (en) * 1983-10-21 1984-03-08 Ritter Starkstromtechnik GmbH & Co, 4600 Dortmund Contact arrangement for vacuum switches
DE3318226A1 (en) * 1983-05-19 1984-11-22 Sachsenwerk, Licht- und Kraft-AG, 8000 München Vacuum switch with double interruption
US4553002A (en) * 1983-12-05 1985-11-12 Westinghouse Electric Corp. Axial magnetic field vacuum-type circuit interrupter
DE4446672A1 (en) * 1994-12-15 1996-09-12 Slamecka Ernst Vacuum switch contact arrangement for medium- to high-voltage equipment

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2643036B2 (en) * 1991-06-17 1997-08-20 三菱電機株式会社 Vacuum switch tube

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1478702A (en) * 1973-09-10 1977-07-06 Tokyo Shibaura Electric Co Vacuum interrupter
DE3107155A1 (en) * 1981-02-26 1982-09-09 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Vacuum switch
DE3112407A1 (en) * 1981-03-28 1982-04-08 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Switching contact for vacuum switches
DE3130466A1 (en) * 1981-07-23 1983-02-17 Calor-Emag Elektrizitäts-Aktiengesellschaft, 4030 Ratingen Contact for a vacuum switch
DE3318226A1 (en) * 1983-05-19 1984-11-22 Sachsenwerk, Licht- und Kraft-AG, 8000 München Vacuum switch with double interruption
DE3338254A1 (en) * 1983-10-21 1984-03-08 Ritter Starkstromtechnik GmbH & Co, 4600 Dortmund Contact arrangement for vacuum switches
US4553002A (en) * 1983-12-05 1985-11-12 Westinghouse Electric Corp. Axial magnetic field vacuum-type circuit interrupter
DE4446672A1 (en) * 1994-12-15 1996-09-12 Slamecka Ernst Vacuum switch contact arrangement for medium- to high-voltage equipment

Also Published As

Publication number Publication date
GB2511373B (en) 2018-01-03
GB201218975D0 (en) 2012-12-05
GB201318392D0 (en) 2013-12-04
GB2507262A (en) 2014-04-30

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