US3641394A - Vacuum switch assembly - Google Patents

Vacuum switch assembly Download PDF

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Publication number
US3641394A
US3641394A US38659A US3641394DA US3641394A US 3641394 A US3641394 A US 3641394A US 38659 A US38659 A US 38659A US 3641394D A US3641394D A US 3641394DA US 3641394 A US3641394 A US 3641394A
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US
United States
Prior art keywords
surge
unbalance
star
voltage
detecting
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
US38659A
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English (en)
Inventor
Kengo Hirose
Noboru Ishiwata
Todaomi Hukawa
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.)
Toyo Denki Seizo KK
Toyo Electric Manufacturing Ltd
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Toyo Electric Manufacturing Ltd
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Publication date
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Publication of US3641394A publication Critical patent/US3641394A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
    • H02H9/06—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using spark-gap arresters
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
    • H02H7/222—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for switches
    • 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

Definitions

  • VACUUM SWITCH ASSEMBLY Inventors: Kengo Hirose, Tokyo; Noboru Ishiwata, Yokosuka; Todaomi Hukawa, Odaware,
  • ABSTRACT A polyphase vacuum switch assembly having a.plurality of vacuum switching valves, a star-connected surge-absorbing unit connected in parallel with a load circuit, and a star-connected unbalance-detecting unit connected substantially in parallel with the surge-absorbing unit.
  • the surge-absorbing unit repeatedly absorbs frequently occuring switching surge voltages while effecting emergency backup absorption of lightning surges with follow-current interruption by melting fuses incorporated therein.
  • the unbalance-detecting unit detccts the melting of the fuse and other unbalance of the load circuit.
  • This invention relates to a vacuum switch assembly, and more particularly to a polyphase vacuum switch assembly for high-voltage circuits, which ensures reliable switching operation while protecting its loads against any dangerous surge voltages and against deterioration of vacuum in the switching assembly itself.
  • the vacuum switch assembly of the invention protects its loads against surge voltages caused by current chopping, as well as surge voltages generated by reclosures, discharge streamers, and uneven closing of polyphase circuits.
  • the vacuum switch assembly also detects any deterioration in the vacuum of switching valves thereof, so as to provide indicating or alarm signals to operators or control means in response to such detection.
  • an electrode material consisting, for instance of Cu-W alloy or Cu-Bi-Sb alloy, is provided on the surface of the switching electrodes for effecting easy vaporization to prevent an occurrence of surge voltage caused by chopping effect, when the switch is opened at a comparatively low load current.
  • the electrode material for preventing the occurrence of chopping tends to deteriorate in a comparatively short period so that the life of the switch is limited.
  • such electrode material which tends to fuse, limits the switching capacity.
  • such fusible alloy may melt together under a heavy current so that a switching accident may happen.
  • such known-type switch is costly and very delicate in the design and handling.
  • a vacuum switch assembly equipped with a simple surge-absorbing unit consisting of discharge gaps, resistors in series with the discharge gaps, and fuses.
  • the surge-absorbing unit is so simplified that it can easily be united with the vacuum switch assembly in a very compact form for providing an economical and efficient vacuum switch assembly.
  • Another object of the present invention is to provide an efficient unit for quickly detecting such insufficient degree of vacuum in the switching valve of vacuum switches, which unit is very simple in construction.
  • the detecting unit of the invention is also effective in finding any lack of normal voltage due to faulty conditions, such as a molten fuse or line breakage.
  • FIG. 1 is a schematic diagram, showing a surge absorber, usable in the present invention
  • FIG. 2 is a schematic diagram illustrating an embodiment of the present invention
  • FIG. 3 is a diagrammatic illustration of a modified surge absorber, which can be used in a vacuum switch assembly of the present invention
  • FIGS. 4 and 5 are oscillographic diagrams, showing the relation between the interruption of load currents and the generation of quick voltage oscillation immediately after the interruption.
  • FIG. 6 is an oscillographic diagram illustrating the manner in which an insufficient degree of vacuum in a switching valve is detected.
  • a vacuum switch assembly of the invention which is generally designated by a reference numeral 20, is inserted between a power source 1, such as a generator or a transformer, and a load 3.
  • the vacuum switch assembly 20 comprises a switching valve unit 2, which selectively completes and interrupts the circuit from the power source I to the load 3, and discharge gaps 4 connected in parallel with the load 3, through fuses 6 and resistors 5, respectively.
  • the illustrated embodiment is adapted for the three-phase application, but the present invention is not restricted to three-phase alone, but the vacuum switch assembly of the invention can be suitably modified for any balanced polyphase system.
  • Each of the discharge gaps 4 is so adjusted as to flash over at a preselected voltage higher than the operation voltage of the circuit including the power source 1 and the load 3, but lower than the insulating strength of the circuit.
  • the resistance value of the resistors 5, in a preferred embodiment, increases when the discharge currents flow therethrough, so as to ensure the interruption of the follow currents through the gaps.
  • the vacuum switch assembly of the aforesaid construction when the magnitude of a surge voltage, which is generated in response to opening of the switching unit 2, increases in excess of the aforesaid preselected flashover voltage, one or more gaps 4 flashover depending on whether such high switching surge voltage is generated in one or more phases.
  • the energy of the switching surge is mostly dissipated as heat in the resistors.
  • the magnitude of the flashover current is comparatively low, i.e., a few amperes at most.
  • the maximum flashover current through the discharge gaps 4 is restricted within a certain limit by the currentchopping characteristics of the switching unit 2. When such flashover current flows through the circuit with a certain surge impedance, there will be generated a surge voltage across the surge impedance.
  • the magnitude of the surge voltage also depends on the chopping characteristics of the switching unit 2.
  • the resistors 5 are so designed as to quickly absorb the discharge energy or surge energy, whenever the discharge gaps 4 flashover. whereby, the interruption of the follow current through the discharge gaps is ensured. As a result, the discharge current does not give any adverse effects to the discharge gaps, so that the discharge gaps can withstand a number of repeated flashover, without any substantial melting or deterioration.
  • the conventional lightning arresters (not shown) are expected to operate without waiting for the flashover of the discharge gaps 4 of the vacuum switching assembly 20 of the invention. If, however, the conventional lightning arresters should fail to properly operate, and if the surge voltage in the system surpasses the predetermined flashover voltage of the discharge gaps 4, the discharge gaps 4 may flashover and a follow current corresponding to the short circuit current of power source system will flow through the discharge gaps 4. In this case, all of the fuses 6 which carry such follow current melt away to interrupt the short circuit current.
  • the resistors may be provided with the aforesaid nonlinear resistance characteristics, so that the resistance value of the resistors 5 increases in response to such surge current, for facilitating the interruption of the follow current therethrough.
  • the fuses 6, resistors 5, and the discharge gaps 4 are connected in series in the aforesaid order, starting from the load side.
  • the arrangement of such elements of the vacuum switch assembly is not restricted to that of FIG. 1.
  • such elements can be arranged in the order of discharge gaps 4, fuses 6, and resistors 5, as illustrated in FIG. 3.
  • FIG. 2 illustrates another embodiment of the present invention.
  • a surge-absorbing unit consisting of fuses 6, resistors 5, and discharge gaps 4 is connected to a circuit between a switching unit 2 and a load 3, in parallel with the load 3.
  • a vacuum switch assembly 20 of this embodiment includes an unbalanced-detecting unit.
  • the unbalancedetecting unit includes three high-impedance elements, e.g., capacitors 7, which are connected in star, so that the neutral point of the capacitors 7 thus connected is grounded through a rectifier 8 and a DC capacitor 9.
  • the opposite ends of the starconnected capacitors 7 are connected to the joints between corresponding resistors 5 and the discharge gaps 4, respectively.
  • One of the fuses 6 is melted away, for instance by follow currents subsequent to the flashover of the corresponding discharge gap 4.
  • Any one phase of the polyphase load 3 is interrupted by some reasons or other, while leaving other phases as closed.
  • the degree of vacuum in any one or two of the switching valves in the switching unit 2 is deteriorated to a level lower than that of the remaining switching valves of the unit 2.
  • the potential at the neutral point of the star-connected capacitors 7 becomes to have a finite value relative to the ground potential.
  • the DC capacitor 9 is charged by such finite neutral voltage through the rectifier 8.
  • a discharge element 10 is actuated, so as to operate an indicator 11 or the like.
  • each capacitor 7 is essentially a line to ground voltage, and if this voltage should exceed a certain predetermined level, the discharge gap 4 flashes over. Accordingly, there is no need for extra insulation for the capacitors 7 of the unbalance-detecting unit.
  • the operation of the surge absorbing unit of this embodiment is identical with that of the preceding embodiment, as described in detail hereinbefore, referring to FIG. 1.
  • the capacitors 7 of the embodiment of FIG. 2 act to reduce the steepness of surge voltage generated in response to the chopping of the load current.
  • the embodiment of FIG. 2 is not a mere combination of the surge-absorbing unit of FIG. 1 and an unbalance-detecting unit, but it has synergistic effects of reducing the steepness of surge voltages in the circuit.
  • FIG. 6 shows the result of a test of the vacuum switch assembly of the invention for detecting the deterioration in the degree of vacuum in a switching valve, the T-phase valve in this case.
  • FIG. 6 shows that the insufficient degree of vacuum in the T- phase switching valve was clearly detected, and a backup circuit breaker was actuated in 3.22 seconds in the illustrated test.
  • surge voltage of frequently occurring magnitude can be absorbed by a surge absorbing unit including discharge gaps, resistors, and fuses, while rarely occurring extra high surges, e.g., lightning surges, are left to conventional lightning arresters, but failure of the operation of such lightning arresters can be backed up by the flashover of the discharge gaps with follow currents being interrupted by the melting of the fuse.
  • the melting of the fuse, or any other unbalance in the voltage of the loadcircuit can be detected by an unbalance-detecting unit consisting of star-connected detecting impedance elements, e.g., capacitors, whose neutral point is grounded through a rectifier and a DC capacitor.
  • the DC capacitor is charged in response to the occurrence of an unbalance of the load circuit, and voltage across the DC capacitor is monitored for the detection of the unbalance, by a suitable monitoring means, such as a discharge valve and a relay.
  • the resistors 5 by resistive material having high temperature coefficient so that to limit the discharge current as far as possible.
  • the unit of this circuit can have an effect of interrupting the follow current.
  • a polyphase vacuum switch assembly comprising vacuum switching valves which are in series with the load and the same in number with the phases of a loadcircuit, a starconnected unbalance-detecting unit connected to the load circuit in parallel therewith, a rectifier connected to neutral point of the unbalance-detecting circuit, a DC capacitor connected between the rectifier and the ground so as to be charged by the neutral voltage through the rectifier, and a DC voltage monitor detecting a voltage across the DC impedance element.
  • a polyphase vacuum switch assembly comprising vacuum switching valves which are in series with the load and the same in number with the phases of a load circuit;
  • each arm of said star-connected unbalance-detecting unit comprises a high capacitive impedance element whose free end is connected to a point on a corresponding arm of the surge-absorbing unit, the high capacitive impedance elements of the unbalance-detecting unit simultaneously functioning as absorbing elements in the surge-absorbing unit.
  • a polyphase vacuum switch assembly which includes vacuum switching valves which are in series with the load and the same in number as the phases of a load circuit;
  • each arm of the star-connected surge-absorbing unit consisting of a series circuit including a discharge gap, a resistor, and a fuse successively connected from the neutral point of the star connection;
  • each arm of said star-connected unbalance-detecting unit comprises a high-impedance capacitor element whose free end is connected respectively to a point between the resistor and the air gap of the corresponding arm of the surge-absorbing unit, whereby the high impedance capacitor element in the unbalance-detecting unit functions as an absorbing element in the surge-absorbing unit.

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  • Emergency Protection Circuit Devices (AREA)
  • High-Tension Arc-Extinguishing Switches Without Spraying Means (AREA)
US38659A 1969-05-22 1970-05-19 Vacuum switch assembly Expired - Lifetime US3641394A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP44039453A JPS4947661B1 (enrdf_load_stackoverflow) 1969-05-22 1969-05-22

Publications (1)

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US3641394A true US3641394A (en) 1972-02-08

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Application Number Title Priority Date Filing Date
US38659A Expired - Lifetime US3641394A (en) 1969-05-22 1970-05-19 Vacuum switch assembly

Country Status (5)

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US (1) US3641394A (enrdf_load_stackoverflow)
JP (1) JPS4947661B1 (enrdf_load_stackoverflow)
DE (1) DE2025120C3 (enrdf_load_stackoverflow)
FR (1) FR2048650A5 (enrdf_load_stackoverflow)
GB (1) GB1285283A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3693053A (en) * 1971-10-29 1972-09-19 Gen Electric Metal oxide varistor polyphase transient voltage suppression
US3911322A (en) * 1974-03-05 1975-10-07 Westinghouse Electric Corp Method and circuit arrangement for an improved low cost lightning arrester
US4366474A (en) * 1980-04-15 1982-12-28 Enertec Identification of electric power network phases experiencing disturbances
US4652867A (en) * 1984-09-25 1987-03-24 Masot Oscar V Circuit breaker indicator
WO2005112218A1 (en) * 2004-05-18 2005-11-24 Abb Oy Earthing and overvoltage protection arrangement
CN107768185A (zh) * 2016-08-16 2018-03-06 中国石油化工股份有限公司 一种真空室的真空度监测方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8820953D0 (en) * 1988-09-07 1988-10-05 Furse W J & Co Ltd Apparatus suitable for use in protecting electrical installations from transients
RU2304835C1 (ru) * 2006-01-10 2007-08-20 Государственное унитарное предприятие "Всероссийский электротехнический институт им. В.И. Ленина" Устройство защиты от перенапряжений

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US897211A (en) * 1907-03-15 1908-08-25 Gen Electric Protective device for electrical systems.
US981742A (en) * 1907-06-01 1911-01-17 Gen Electric Lightning-arrester.
US2520956A (en) * 1947-03-14 1950-09-05 James P Parker Breakdown indicator for insulated aircraft antennas
US3158785A (en) * 1961-07-03 1964-11-24 Charbonnages De France Devices for detecting earth faults in electric distribution networks

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US897211A (en) * 1907-03-15 1908-08-25 Gen Electric Protective device for electrical systems.
US981742A (en) * 1907-06-01 1911-01-17 Gen Electric Lightning-arrester.
US2520956A (en) * 1947-03-14 1950-09-05 James P Parker Breakdown indicator for insulated aircraft antennas
US3158785A (en) * 1961-07-03 1964-11-24 Charbonnages De France Devices for detecting earth faults in electric distribution networks

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3693053A (en) * 1971-10-29 1972-09-19 Gen Electric Metal oxide varistor polyphase transient voltage suppression
US3911322A (en) * 1974-03-05 1975-10-07 Westinghouse Electric Corp Method and circuit arrangement for an improved low cost lightning arrester
US4366474A (en) * 1980-04-15 1982-12-28 Enertec Identification of electric power network phases experiencing disturbances
US4652867A (en) * 1984-09-25 1987-03-24 Masot Oscar V Circuit breaker indicator
WO2005112218A1 (en) * 2004-05-18 2005-11-24 Abb Oy Earthing and overvoltage protection arrangement
US20070121269A1 (en) * 2004-05-18 2007-05-31 Abb Oy Earthing and overvoltage protection arrangement
US7656638B2 (en) * 2004-05-18 2010-02-02 Abb Oy Earthing and overvoltage protection arrangement
CN1954471B (zh) * 2004-05-18 2010-06-16 Abb有限公司 接地和过电压保护装置
CN107768185A (zh) * 2016-08-16 2018-03-06 中国石油化工股份有限公司 一种真空室的真空度监测方法
CN107768185B (zh) * 2016-08-16 2020-01-10 中国石油化工股份有限公司 一种真空室的真空度监测方法

Also Published As

Publication number Publication date
GB1285283A (en) 1972-08-16
JPS4947661B1 (enrdf_load_stackoverflow) 1974-12-17
FR2048650A5 (enrdf_load_stackoverflow) 1971-03-19
DE2025120C3 (de) 1974-06-27
DE2025120A1 (enrdf_load_stackoverflow) 1970-12-23
DE2025120B2 (de) 1972-07-06

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