EP0945951B1 - Improved gas-accumulation Buchholz relay - Google Patents

Improved gas-accumulation Buchholz relay Download PDF

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Publication number
EP0945951B1
EP0945951B1 EP99104056A EP99104056A EP0945951B1 EP 0945951 B1 EP0945951 B1 EP 0945951B1 EP 99104056 A EP99104056 A EP 99104056A EP 99104056 A EP99104056 A EP 99104056A EP 0945951 B1 EP0945951 B1 EP 0945951B1
Authority
EP
European Patent Office
Prior art keywords
relay
pivot
float
magnet holder
semitubular
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
EP99104056A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0945951A3 (en
EP0945951A2 (en
Inventor
Silvio Dal Lago
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.)
Comem SpA
Original Assignee
Comem SpA
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Filing date
Publication date
Application filed by Comem SpA filed Critical Comem SpA
Publication of EP0945951A2 publication Critical patent/EP0945951A2/en
Publication of EP0945951A3 publication Critical patent/EP0945951A3/en
Application granted granted Critical
Publication of EP0945951B1 publication Critical patent/EP0945951B1/en
Anticipated expiration legal-status Critical
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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
    • H01H33/02—Details
    • H01H33/53—Cases; Reservoirs, tanks, piping or valves, for arc-extinguishing fluid; Accessories therefor, e.g. safety arrangements, pressure relief devices
    • H01H33/55—Oil reservoirs or tanks; Lowering means therefor
    • H01H33/555—Protective arrangements responsive to abnormal fluid pressure, liquid level or liquid displacement, e.g. Buchholz relays
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H35/00—Switches operated by change of a physical condition
    • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
    • H01H35/40—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow actuated by devices allowing continual flow of fluid, e.g. vane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H36/00—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding
    • H01H36/02—Switches actuated by change of magnetic field or of electric field, e.g. by change of relative position of magnet and switch, by shielding actuated by movement of a float carrying a magnet

Definitions

  • the present invention relates to an improved gas-accumulation Buchholz relay.
  • This decomposition of the insulators is caused by their overheating or by the onset of electric arcs.
  • the Buchholz relay must be installed in the transformer below the expansion vessel, commonly known as conservator, and is filled with oil during normal operation.
  • this type of relay is constituted by a body which is obtained from aluminium alloy castings inside which a supporting flame for at least one movable device is arranged; the movable device comprises a float for actuating at least one magnetic switch of a per se known type enclosed in a bulb.
  • Buchholz relays are usually provided with an upper float which enables and disables an alarm circuit and with a lower float which is directly connected to a disconnection circuit.
  • This accumulation of gas inside the body of the relay causes a lowering of the level of the oil that is detected by the upper float, which accordingly actuates the magnetic switch with which it is associated and by means of which the alarm circuit is closed.
  • Buchholz relays all have a further protection which is capable of detecting strong oil currents generated, for example, by short-circuits.
  • This protection is constituted by a suitably adjusted flap which is sensitive to the flow-rate of the oil current and is also connected to the circuit for disconnecting the transformer from the power supply.
  • This type of relay is also used to signal any leaks of oil from the tank of the transformer, because in this case also the general level of the oil lowers and accordingly the floats move downward.
  • This lowering of the floats determines the activation of the external alarm and/or disconnection circuits connected thereto.
  • a Buchholz relay of this type having all the features of the preamble of claim 1 is known for example from BE 678625 A
  • the relays be capable of operating correctly in the presence of vibrations caused by seismic activity.
  • the aim of the present invention is to provide a Buchholz relay which is sensitive to variations in the level of the oil and insensitive to the occurrence of vibrations due to seismic activities or maneuvers for starting the transformer, adequately acting on the alarm and/or disconnection circuits.
  • an important object of the present invention is to provide a Buchholz relay which ensures good characteristics in terms of assured intervention.
  • Another important object is to provide a Buchholz relay whose configuration is simpler than that of conventional types.
  • Another object of the present invention is to provide a Buchholz relay whose assembly and maintenance are simpler and quicker to perform with respect to conventional relays.
  • a gas-accumulation Buchholz relay which comprises, to be immersed in an oil bath, a supporting frame for magnetic switches for closing circuits and at least one movable device of the float type for actuating said switches, characterized in that said float is of the lever type with a rotation axis which is fixed to said frame and is operatively connected to a magnet holder which acts as a counterweight, said float being articulated in its rotation with respect to said magnet holder through a given angle.
  • an oil-filled transformer is generally designated by the reference numeral 10 and has a tank with radiators 11 above which an expansion vessel 12 of a per se known type is connected.
  • the transformer 10 is conventional and Figure 1 illustrates high-voltage insulators 13, an oil drain 14 and a thermometer 15 for detecting the temperature of the oil.
  • the transformer 10 is provided with a Buchholz relay, according to the invention, which is generally designated by the reference numeral 16 and is integrated between the transformer and the expansion vessel 12.
  • the relay 16 is constituted by a body 17 which is preferably hermetic and made of cast aluminum alloy and in which inspection ports 18 are defined, preferably made of tempered glass or very sturdy plastics, provided with graduated scales 19.
  • the relay 16 is provided with a cover 20 from which a cock 21 for discharging the gas and a pneumatic test valve 22 protrude.
  • the frame 23 is arranged inside the relay 16, is made of plastics, and is provided, in an upward region, with through holes 24 for engagement with the cover 20 by way of fixing screws which are not shown in the above figures for the sake of simplicity.
  • the frame 23 has, in this configuration, a mainly longitudinal structure which includes two uprights 25 in which there are seats 26 for accommodating magnetic switches 27.
  • Each one of said switches 27 is conventional and has, inside a bulb, a magnet and electric contacts, not shown in the figures, which are directly connected to an alarm circuit and/or to a disconnection circuit.
  • An upper movable device 28 and an equivalent lower movable device 29 are fixed to the frame 23.
  • Each one of the movable devices 28 and 29 comprises a float 30 of the lever type, which has a substantially ovoid structure in which there are flat regions 31 and from which an arm 32 protrudes starting from a longitudinal band of the float 30.
  • First and second elastic curved wings 34a and 34b protrude from said arm 32 and define, as a whole, a semitubular profile 33.
  • first wing 34a is shorter than the second wing 34b, so as to form, together with the second wing and at each end, a seat 35 which covers a reduced angle in cross-section.
  • a pivot 36 is inserted in the semitubular profile 33 and is appropriately shaped complementarily to the wings 34a and 34b.
  • a radial extension 36a protrudes at each end from said pivot 36, which constitutes the rotation axis for the float 30; a magnet holder 37 is associated with the radial extension, parallel to the pivot 36, has a substantially tubular configuration and is provided, at its two ends, with elastic teeth 38.
  • Pivot 36 is adapted to be inserted in the semitubular profile 33 between the wings 34a and 34b, so that each extension 36a is arranged at the seat 35.
  • a counterweight 39 can be inserted in the magnet holder 37 and has a cylindrical structure; said counterweight is to be arranged in a central position and in contact, at its two ends, with a first magnet and a second magnet which are respectively designated by the reference numerals 40 and 41 and preferably have a tablet-like structure.
  • the counterweight 39 is preferably made of brass.
  • the first and second magnets 40 and 41 and said counterweight 39 are retained in the magnet holder 37 by way of the snap-on retention provided by the teeth 38 and optionally by way of the presence of a suitable adhesive.
  • First and second guides 42 and 43 are provided in the uprights 25 of the frame 23, respectively in the upper and median parts of the frame 23; the complementarily shaped ends of the pivot 36 of each one of the upper and lower movable devices 28 and 29 can slide along said guides.
  • Each one of the guides 42 and 43 has, in the innermost end portion of its extension, a seat 44 adapted to accommodate the end of the pivot 36 of each one of the movable devices 28 and 29.
  • the movable devices are therefore assembled to the frame 23 by snap action after moving along the guides 42 or 43 with the ends of the pivot 36 for insertion and consequent locking in the seats 44.
  • the Buchholz relay 16 is also provided with a rod-like element 45 which is associated with one of the uprights 25 of the frame 23 and whose upper end is accessible to a user by way of an adapted spring-loaded push-button, which is not shown in the above-cited figures for the sake of simplicity.
  • each level is L-shaped and has, at its engagement end, a tab 48 which is monolithic with a ring 49 inside which said rod-like element 45 is inserted substantially without play.
  • Each lever 46 and 47 can slide along the rod-like element 45 along the path determined respectively by an upper guide 50 and by a lower guide 51, both of which are formed in the upright 25; the tabs 48 of the levers 46 and 47 move along the guides.
  • the levers are required by the relay 16 respectively to mechanically test the alarm circuit, which is associated with the upper movable device 28, and the disconnection circuit, which is associated with the lower movable device 29.
  • Relay 16 also has a flap 52, of a per se known type, which is associated with the frame 23 below the lower movable device 29 and is adapted to detect any presence of strong oil currents inside the relay 16.
  • the operation of the Buchholz relay 16 described with the present invention is extremely simple, since the lever-type floats 30 of the upper and lower movable devices 28 and 29 follow the level of the oil, moving down and up as a function of said level.
  • Said play is determined by the breadth of the angle that the float 30 can move through without transmitting its motion to the two extensions 36a and accordingly to the magnet holder 37.
  • the magnet holder When contact is established between the float 30 of a movable device 28 and 29 and the corresponding magnet holder 37, the magnet holder, by rigidly following the float 30 in its rotation, in fact moves with respect to the frame 23 and so do the first and second magnets 40 and 41 with it.
  • the movement of the first and second magnets 40 and 41 determines an interaction with the magnets contained in the bulb of the switches 27, causing, due to consequent movements between the electric contacts enclosed in the bulb, the closure of the alarm or disconnection circuit connected thereto.
  • the maximum extent of the play that can occur between the lever-type float 30 and the corresponding magnet holder 37 determines the degree of sensitivity of the relay 16 to vibrations.
  • the materials employed, so long as they are compatible with the contingent use, may also be any according to requirements.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • Power Engineering (AREA)
  • Level Indicators Using A Float (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Organic Insulating Materials (AREA)
EP99104056A 1998-03-24 1999-03-17 Improved gas-accumulation Buchholz relay Expired - Lifetime EP0945951B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT98PD000061A ITPD980061A1 (it) 1998-03-24 1998-03-24 Rele' perfezionato ad accumulo di gas tipo buchholz
ITPD980061 1998-03-24

Publications (3)

Publication Number Publication Date
EP0945951A2 EP0945951A2 (en) 1999-09-29
EP0945951A3 EP0945951A3 (en) 2000-06-07
EP0945951B1 true EP0945951B1 (en) 2008-06-25

Family

ID=11392112

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99104056A Expired - Lifetime EP0945951B1 (en) 1998-03-24 1999-03-17 Improved gas-accumulation Buchholz relay

Country Status (5)

Country Link
EP (1) EP0945951B1 (it)
AT (1) ATE399385T1 (it)
DE (1) DE69938948D1 (it)
ES (1) ES2310021T3 (it)
IT (1) ITPD980061A1 (it)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103620719B (zh) * 2011-06-22 2016-07-13 赖茵豪森机械制造公司 布克霍尔茨继电器
ES2560814T3 (es) * 2012-07-20 2016-02-22 Abb Technology Ag Dispositivo de seguridad para un transformador de energía, y transformador de energía relacionado que usa dicho dispositivo de seguridad
CN103681099B (zh) * 2013-12-11 2015-10-14 国家电网公司 一种带远程控制的瓦斯继电器
CN105826128B (zh) * 2015-01-07 2018-06-19 国家电网公司 多功能双浮子气体继电器
CN111161977B (zh) * 2020-01-23 2024-11-05 广东电网有限责任公司 一种多浮筒式瓦斯继电装置
CN112038172B (zh) * 2020-07-15 2023-03-10 国网山东省电力公司青岛供电公司 一种瓦斯继电器自动排气装置、排气方法及瓦斯继电器

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1012247A (fr) * 1949-07-15 1952-07-07 Trist & Co Ltd Ronald Perfectionnements aux dispositifs magnétiques commandés par flotteur
ES324856A1 (es) * 1965-03-30 1967-02-16 Licentia Patent-Verwaltungs G M B H Sistema de vigilancia y de desconexion para aparatos electricos con aislamiento liquido.
US5426271A (en) * 1994-01-18 1995-06-20 Honeywell Inc. Liquid level sensor

Also Published As

Publication number Publication date
ES2310021T3 (es) 2008-12-16
EP0945951A3 (en) 2000-06-07
DE69938948D1 (de) 2008-08-07
ITPD980061A1 (it) 1999-09-24
EP0945951A2 (en) 1999-09-29
ATE399385T1 (de) 2008-07-15

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