US3626125A - Leak detecting means for vacuum switches - Google Patents

Leak detecting means for vacuum switches Download PDF

Info

Publication number
US3626125A
US3626125A US877811A US3626125DA US3626125A US 3626125 A US3626125 A US 3626125A US 877811 A US877811 A US 877811A US 3626125D A US3626125D A US 3626125DA US 3626125 A US3626125 A US 3626125A
Authority
US
United States
Prior art keywords
enclosure
envelope
vacuum switch
liquid
tank
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 - Lifetime
Application number
US877811A
Other languages
English (en)
Inventor
Akira Tonegawa
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.)
Toshiba Corp
Original Assignee
Tokyo Shibaura Electric Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Tokyo Shibaura Electric Co Ltd filed Critical Tokyo Shibaura Electric Co Ltd
Application granted granted Critical
Publication of US3626125A publication Critical patent/US3626125A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • H01H33/60—Switches wherein the means for extinguishing or preventing the arc do not include separate means for obtaining or increasing flow of arc-extinguishing fluid
    • H01H33/66—Vacuum switches
    • H01H33/668—Means for obtaining or monitoring the vacuum
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
    • G01M3/202—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material using mass spectrometer detection systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/0005—Tap change devices
    • H01H2009/0061—Monitoring tap change switching devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/0005—Tap change devices
    • H01H9/0038—Tap change devices making use of vacuum switches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
    • H01H9/0005—Tap change devices
    • H01H9/0044—Casings; Mountings; Disposition in transformer housing

Definitions

  • the present invention relates to means for detecting the lowering of vacuum in vacuum switches.
  • vacuum switches have electrically superior characteristics in comparison with ordinary air circuit breakers in that they provide an extremely large dielectric strength during the separation of electrodes thereof because of extremely high dielectric strength of high vacuum, in which the electrodes make and break an electric circuit having a relatively high voltage level. For this reason, there may be provided an extremely small distance between the contact surfaces of the electrodes to resist a high voltage thereacross, whereby the switch structure becomes smalland inexpensive to manufacture.
  • the vacuum switch has further advantages including an excellent electric power interrupting performance due to a rapid difiusion of metal vapors generated by the high-temperature are drawn out between the separated electrodes.
  • the vacuum switch comprises an envelope made of glass or ceramic material and highly evacuated to a degree of vacuum of the order to 10* mm. Hg, a stationary electrode having its one end disposed within the envelope and the other extended vacuum-tightly through a wall of the envelope, a movable electrode having opposite ends similar to those of the stationary electrode, metal bellows arranged around an intermediate portion in the lengthwise direction of the movable electrode thereby to form a vacuumtight structure between the envelope and the movable electrode and the maintain flexibility for moving the movable electrode.
  • the vacuum switch has an exhausting pipe which is sealed off after exhausting of the interior of the envelope.
  • At least one vacuum switch comprising a highly evacuated envelope made of an insulating material and a pair of electrodes so disposed within said envelope that they are movable relative to each other to make and break an electric circuit.
  • a liquid-tight enclosure enclosing the vacuum switch with an insulating liquid and having at least one opening, and the liquid within the enclosure is communicates with that within an enclosed tank through openings provided in the walls of the former and the latter, respectively.
  • the tank functions as a level gauge for the liquid enclosed therein, and the level of the liquid varies when the vacuum within the vacuum switch is broken.
  • FIG. 1 is an elevational view, in vertical section, showing leakage-detecting means embodying the present invention.
  • FIG. 2 is a schematic diagram of a power transformer with an onload tap changer embodying the present invention.
  • a vacuum switch shown therein and generally designated by reference numeral 10 normally includes a highly evacuated envelope 47 made of an insulating material such as glass or ceramics, a stationary rodlike electrode ll vacuum-tightly extending through an upper wall of the envelope and having a butt contact surface at its lower end, a movable rodlike electrode 12 movably extending through a lower wall of the envelope and having a butt contact surface at the upper end thereof, and metal bellows l3 arranged between an opening 14 on the lower wall of the en velope and an intermediate portion in the lengthwise direction of the movable electrode.
  • the vacuum switch 10 is mounted within an enclosed enclosure 15 which comprises a cylindrical insulating member 16 and upper and lower covers 17 and 18 for the cylindrical member 16 to liquid-tightly close upper and lower openings 19 and 20 of the cylindrical member.
  • the interior of the enclosure 15 is filled with any suitable insulating liquid 21, for example, an electric insulating oil or pure water, for a purpose hereinafter described.
  • the cover plates 17 and 18 are made of metal and serve as supports for the vacuum switch 10 and so sealing means for preventing leakage of the liquid 28 out of the enclosure 15.
  • the cylindrical member 16 functions to insulate one of the electrodes from the other.
  • Stationary electrode 11 extends outwardly at one end thereof through upper cover 17, and, of course, a suitable oiltight means is provided at the part where the rod passes through the cover.
  • a suitable oiltight means is provided at the part where the rod passes through the cover.
  • the movable electrode 12 slidably extends through the lower cover 18 there are provided an oil seal 22 to prevent leakage of the liquid 21 and a guide bearing 23 to slidably support the rod.
  • the drive means 25 may be an electromagnetic actuator, a motor operating mechanism, or a hydraulic actuator.
  • an oil leveler or tank 26 which includes a cylindrical casing 27 containing a quantity of oil 28 and a space 29 above the surface of the oil therein.
  • the tank 26 has a partition plate 30 disposed therewithin to form an upper wall of the space 29 and a tubular pipe member 31 depends from the plate 30 to a point near the bottom of tank 27.
  • the upper opening of the tank 37 is closed by a cover plate 32 which also functions as an oil packing for the tank and has also a tubular pipe 33 integrally formed with the plate 32 and having an opening 46.
  • an elongated tubular pipe 34 is oil-tightly attached around the pipe 33 on the cover plate 32, and the other end thereof is oil-tightly attached to the bottom of the enclosure 15 through a flanged packing member 35 and an opening 36 formed in the bottom cover 18 of the enclosure.
  • the oil 21 in the interior of the enclosure 15 can communicate with the oil 28 within the tank 26.
  • an oil leveler 37 which comprises a part of the sidewall of the tank 26, aframework 38 and a window 39 made of a transparent material, for example, glass or a synthetic resin.
  • a pair of bridge contacts 40 (only one of which is shown) disposed at the lower portion in the oil leveler 37, and a movable contact 41 floating in the oil of the leveler.
  • the sidewall of the tank 26 at the upper and lower portions of the leveler is provided with openings 42 and 43, respectively, which connect the interior of the tank 26 with that of the leveler.
  • the vacuum switch makes and breaks the electric circuit connected thereto (not shown) by the operation of the drive means through the insulating tube member 24 connected at its upper end to the lower end of the movable electrode 12.
  • the tank 26 When variations in the volume of the oil in enclosure occur due to the variations of the ambient temperature, a part of the oil in the enclosure flows into the tank 26 through opening 36, pipe 34, opening 46 and pipe 31, and vice versa, whereby the variations of the oil in the enclosure 15 are efiectively absorbed by the space 29 above the oil surface in the tank 26. Accordingly, the tank 26 also acts as an oil conservator.
  • the vacuum switch 10 which comprises any one of the aforesaid ones, for example, a leak due to a crack in bellows l3 and leaks at the brazed portions which lie at the portions between envelope 10 and electrodes 11 and 12 as well as those which lie among bellows l3, envelope 47 and movable electrode 12. It will be apparent that the oil 21 within the enclosure 15 will then flow into the interior of envelope 47 through any one of the aforesaid damaged portions of the vacuum switch thereby to fill the space within the envelope with oil.
  • the oil 28 contained in the tank 26 moves into the enclosure 15 through an oil path which comprises the tubular member 31, an opening 31, an opening 46 of the cover plate 32, the insulating tubular pipe 34 and the opening 36 arranged on the bottom plate 18 of the enclosure.
  • the surface of the oil 28 in the tank 26 will take a new lower level substantially corresponding to the amount of oil which has entered into the envelope of the vacuum switch, and the floating contact 41 will engage with the bridge contacts 40.
  • the apparatus disclosed herein can be adapted for the electric power circuit interrupter for an electric power circuit in which a vacuum switch is employed as the power interrupter.
  • FIG. 2 a more significant utility of the present invention lies in its application to an onload tap changer for an electric transformer as shown in FIG. 2.
  • FIG. 2 like parts are denoted by the same numerals as those employed in FIG. 1, and for simplifying the illustration, the outer casing 48 for the transformer is shown only with a chain line.
  • a tapped winding 49 schematically illustrated and having a plurality of odd-numbered taps la, 3a and 7a and a plurality of even numbered taps 2b, 4b, 6b, and 8b together with a magnetic core (not shown).
  • gearbox 52 is also connected to selector switches 50 and 51 to effect the changing switch operations in a predetermined sequence.
  • the aforesaid parts are located within the casing 48 with an electric insulating and cooling oil 60 except the motor 53 and the gearbox 52.
  • the stationary electrodes 11a and 11b of pairs of vacuum switches 10a and 10b are connected with each other through a current limiting resistor 62, connecting the electrode 11a to selector switch 50, similarly connecting the stationary electrodes 11c and 114 to each other through a resistor 63 and connecting the electrode to selector switch 51. While all of the movable electrodes 12a, 12b, 12c and 12d are connected together with and connected to a high potential terminal (not shown).
  • the switch 10b closes, after which switch 10a opens, and, at the same time, switch 10d closes, whereby taps 5a and 5b are simultaneously connected through resistors 62 and 63 to the high potential terminal, and a short circuit occurs across the taps 4a and 5a momentarily.
  • the short circuit current is suppressed to a relatively small value by both resistors 62 and 63.
  • the switch 10b opens, switch 59 closes, then switch 58 opens, and lastly the selector switch 50 is changed from tap 5a to 3a.
  • tap changing operation is also made in a reverse direction when the input voltage for the transformer exceeds a predetermined value, and, thus, the output voltage of transformer is always adjusted to hold the predetermined value.
  • a relay box 62 is provided on the cover plate 61 of the easing 48, which box includes four bellows 63 to 66, the interiors of which are separately communicated within four enclosure 15a to 15d through insulating tubular members 67 to 70, respectively, and there are provided insulating liquid or noncompressible fluid 21a to 21d within the prescribed parts, respectively.
  • Normally closed contacts 71, 72, 73 and 74 are combined with the bellows, which contacts are connected in series with the circuit 45.
  • the circuit comprising conductors 45 opens to generate an alarm and at the same time to stop the tap changing operation which is initiated by motor 53 as well as to deenergize the transformer.
  • the tap changing operation for a transformer with an onload tap changer is positively prevented from being affected by the vacuum-broken vacuum switch of the onload tap changer.
  • the same oil be utilized to fill the enclosures 15a to 15d as well as the casing 48 for the purpose of preventing mixing of different kinds of oils, whereby the dielectric strength of one oil is not affected due to that of the other.
  • Switching means to make and break an electric circuit comprising a vacuum switch including a highly evacuated insulating envelope and a pair of separable electrodes having their one ends located within said envelope to be engageable with each other,
  • a liquidtight enclosure arranged around the vacuum switch and having at least one opening extending through a wall thereof,
  • said enclosure being made of an insulating material and filled with a noncompressible fluid
  • said detecting means comprising an enclosed liquid leveler tank, I
  • said tank being partially filled with an noncompressible fluid so as to leave a space above the fluid level therein and having a tubular pipe one end of which is communicated with one end of said insulating tubular member, and the other end is opened in the noncompressible fluid near the bottom of the tank, and an electrical floating switch means arranged in the fluid of said tank and responsive to the fluid level variations in the tank.
  • said drive means being adapted to become inoperative in response to output signals of said interlocking circuit.
  • Switching means for a tap changing electrical power transformer which includes an enclosed casing, a tapped winding enclosed within the casing with an electrical insulating oil and a tap changing mechanism for the tapped winding.
  • each said vacuum switch being arranged within said enclosure in a manner to leave a space filled with an insulating oil therebetween, respectively, and
  • a vacuum switch including a highly evacuated insulating envelope and a pair of seperable electrodes having ends located within said envelope and engageable with each other,
  • a liquidtight enclosure enclosingsaid vacuum switch and having walls conforming generally to but spaced from said envelope, the space between the enclosure and the envelope having a limited volume of the order of magnitude of the volume of said envelope, said enclosure being filled with a noncompressible liquid,
  • liquid leveler reservoir means connected with said enclosure to keep said enclosure full of liquid, said reservoir means having a liquid volume that is variable according to liquid required by said enclosure,
  • Columh 6- line 4, delete "winging” and insert--winding-.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Housings And Mounting Of Transformers (AREA)
  • Examining Or Testing Airtightness (AREA)
  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
  • Fluid-Pressure Circuits (AREA)
US877811A 1968-11-22 1969-11-18 Leak detecting means for vacuum switches Expired - Lifetime US3626125A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP43085893A JPS4945434B1 (enrdf_load_stackoverflow) 1968-11-22 1968-11-22

Publications (1)

Publication Number Publication Date
US3626125A true US3626125A (en) 1971-12-07

Family

ID=13871551

Family Applications (1)

Application Number Title Priority Date Filing Date
US877811A Expired - Lifetime US3626125A (en) 1968-11-22 1969-11-18 Leak detecting means for vacuum switches

Country Status (3)

Country Link
US (1) US3626125A (enrdf_load_stackoverflow)
JP (1) JPS4945434B1 (enrdf_load_stackoverflow)
GB (1) GB1277935A (enrdf_load_stackoverflow)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814885A (en) * 1973-07-11 1974-06-04 Gen Electric Method of detecting a leak in a vacuum interrupter located inside a housing containing pressurized gas
US3983345A (en) * 1975-01-30 1976-09-28 General Electric Company Method of detecting a leak in any one of the vacuum interrupters of a high voltage circuit breaker
US4034264A (en) * 1974-04-02 1977-07-05 Siemens Aktiengesellschaft Arrangement for detecting a deficient operational capability of a vacuum switching vessel
US4393286A (en) * 1978-08-24 1983-07-12 Tokyo Shibaura Denki Kabushiki Kaisha Vacuum circuit breakers
EP0168340A1 (de) * 1984-06-28 1986-01-15 Siemens Aktiengesellschaft Vakuumschalter mit einer Einrichtung zur Überwachung des Vakuums
WO2001091151A1 (en) * 2000-05-23 2001-11-29 Abb Power T & D Company Inc. Combination of a vacuum interruption device and oil-filled transformer
US6492609B1 (en) * 1999-11-08 2002-12-10 Alstom Power station switch with a radiator/heat-exchanger
US6723940B1 (en) * 1999-04-13 2004-04-20 Abb Inc. Encapsulated magnetically actuated vacuum interrupter with integral bushing connector
US20060181267A1 (en) * 2005-02-15 2006-08-17 Eaton Corporation Vacuum circuit interrupter including circuit monitoring leakage or loss of vacuum and method of monitoring a vacuum interrupter for leakage or loss of vacuum
EP1984933A4 (en) * 2006-01-31 2009-05-27 Thomas & Betts Int VACUUM TYPE ELECTRICAL SWITCHING APPARATUS
US20140339195A1 (en) * 2012-02-03 2014-11-20 Abb Technology Ag Vacuum interrupter with transition areas between metal housing parts and ceramic housing parts covered by insulating material
US20150047954A1 (en) * 2011-03-25 2015-02-19 Abb Technology Ag Tap changer
WO2013119288A3 (en) * 2012-02-09 2015-06-18 G & W Electric Company Solid-dielectric switch including a molded viewing window
US20170186574A1 (en) * 2014-09-12 2017-06-29 Abb Schweiz Ag Pole part for high pressure environment application
CN114923682A (zh) * 2022-05-17 2022-08-19 北京通嘉宏瑞科技有限公司 一种轴封寿命加速验证试验机及试验方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2471864A (en) * 2009-07-15 2011-01-19 Lucy And Co Ltd W Vacuum circuit breaker surrounded by fluid

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1796746A (en) * 1926-11-02 1931-03-17 Buchholz Max Protection of electrical apparatus
US3206569A (en) * 1964-12-17 1965-09-14 Orin P Mccarty Protective means for transformer tap changer
US3404247A (en) * 1966-03-08 1968-10-01 Gen Electric Pressure responsive protective means for vacuum type circuit interrupters

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1796746A (en) * 1926-11-02 1931-03-17 Buchholz Max Protection of electrical apparatus
US3206569A (en) * 1964-12-17 1965-09-14 Orin P Mccarty Protective means for transformer tap changer
US3404247A (en) * 1966-03-08 1968-10-01 Gen Electric Pressure responsive protective means for vacuum type circuit interrupters

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814885A (en) * 1973-07-11 1974-06-04 Gen Electric Method of detecting a leak in a vacuum interrupter located inside a housing containing pressurized gas
US4034264A (en) * 1974-04-02 1977-07-05 Siemens Aktiengesellschaft Arrangement for detecting a deficient operational capability of a vacuum switching vessel
US3983345A (en) * 1975-01-30 1976-09-28 General Electric Company Method of detecting a leak in any one of the vacuum interrupters of a high voltage circuit breaker
US4393286A (en) * 1978-08-24 1983-07-12 Tokyo Shibaura Denki Kabushiki Kaisha Vacuum circuit breakers
EP0168340A1 (de) * 1984-06-28 1986-01-15 Siemens Aktiengesellschaft Vakuumschalter mit einer Einrichtung zur Überwachung des Vakuums
WO1986000463A1 (en) * 1984-06-28 1986-01-16 Siemens Aktiengesellschaft Vacuum switch with vacuum control device
US6723940B1 (en) * 1999-04-13 2004-04-20 Abb Inc. Encapsulated magnetically actuated vacuum interrupter with integral bushing connector
US6492609B1 (en) * 1999-11-08 2002-12-10 Alstom Power station switch with a radiator/heat-exchanger
WO2001091151A1 (en) * 2000-05-23 2001-11-29 Abb Power T & D Company Inc. Combination of a vacuum interruption device and oil-filled transformer
US7148677B2 (en) * 2005-02-15 2006-12-12 Eaton Corporation Vacuum circuit interrupter including circuit monitoring leakage or loss of vacuum and method of monitoring a vacuum interrupter for leakage or loss of vacuum
US20060181267A1 (en) * 2005-02-15 2006-08-17 Eaton Corporation Vacuum circuit interrupter including circuit monitoring leakage or loss of vacuum and method of monitoring a vacuum interrupter for leakage or loss of vacuum
EP1984933A4 (en) * 2006-01-31 2009-05-27 Thomas & Betts Int VACUUM TYPE ELECTRICAL SWITCHING APPARATUS
US9401249B2 (en) * 2011-03-25 2016-07-26 Abb Technology Ag Tap changer
US20150047954A1 (en) * 2011-03-25 2015-02-19 Abb Technology Ag Tap changer
US20140339195A1 (en) * 2012-02-03 2014-11-20 Abb Technology Ag Vacuum interrupter with transition areas between metal housing parts and ceramic housing parts covered by insulating material
US9425005B2 (en) * 2012-02-03 2016-08-23 Abb Technology Ag Vacuum interrupter with transition areas between metal housing parts and ceramic housing parts covered by insulating material
WO2013119288A3 (en) * 2012-02-09 2015-06-18 G & W Electric Company Solid-dielectric switch including a molded viewing window
US9216527B2 (en) 2012-02-09 2015-12-22 G & W Electric Company Solid-dielectric switch including a molded viewing window
US9659728B2 (en) 2012-02-09 2017-05-23 G & W Electric Company Solid-dielectric switch including a molded viewing window
US20170186574A1 (en) * 2014-09-12 2017-06-29 Abb Schweiz Ag Pole part for high pressure environment application
US10049840B2 (en) * 2014-09-12 2018-08-14 Abb Schweiz Ag Pole part for high pressure environment application
CN114923682A (zh) * 2022-05-17 2022-08-19 北京通嘉宏瑞科技有限公司 一种轴封寿命加速验证试验机及试验方法
CN114923682B (zh) * 2022-05-17 2023-10-24 北京通嘉宏瑞科技有限公司 一种轴封寿命加速验证试验机及试验方法

Also Published As

Publication number Publication date
JPS4945434B1 (enrdf_load_stackoverflow) 1974-12-04
GB1277935A (en) 1972-06-14

Similar Documents

Publication Publication Date Title
US3626125A (en) Leak detecting means for vacuum switches
US3404247A (en) Pressure responsive protective means for vacuum type circuit interrupters
US3356798A (en) Disconnect switch
CN201113292Y (zh) 一种气体绝缘真空环网开关柜
US3720867A (en) Fail safe vacuum type circuit interrupter and associated load current tap changer for electric induction apparatus
US3819892A (en) Fail safe vacuum type circuit interrupter and associated load current tap changer for electric induction apparatus
EP0354494B1 (en) Switch gear
US20020053553A1 (en) Integrated type gas-insulated switching apparatus
US3206569A (en) Protective means for transformer tap changer
US3641359A (en) Monitor circuit for vacuum-type electric circuit interrupter
US3544884A (en) Load tap changer apparatus employing parallel circuits comprising vacuum and no-load switches
US1899746A (en) Protective system for transformers
US3303309A (en) Series connected switches of different types
US2897325A (en) Electric switches for high voltage
RU2730939C2 (ru) Головка переключателя ступеней нагрузки, а также переключатель ступеней нагрузки с головкой переключателя ступеней нагрузки
US2294712A (en) Transformer tap changer arrangement
US3093717A (en) Air blast circuit breaker having a series connected breaking gap in a bushing
KR20240034248A (ko) 가스 절연 전기 장치
US3254170A (en) High pressure float actuated switch
US2235074A (en) Circuit interrupter
US3881080A (en) Low-fluid volume outdoor power circuit breaker
KR102703868B1 (ko) 온-로드 탭 체인저
SU1282234A1 (ru) Вакуумный выключатель
US3928738A (en) Coupling arrangement for a compressed-gas circuit breaker equipped with a hydraulic drive
US2246182A (en) Apparatus for transformer tap changing under load