EP0150130A2 - On-load tap changer - Google Patents
On-load tap changer Download PDFInfo
- Publication number
- EP0150130A2 EP0150130A2 EP85300441A EP85300441A EP0150130A2 EP 0150130 A2 EP0150130 A2 EP 0150130A2 EP 85300441 A EP85300441 A EP 85300441A EP 85300441 A EP85300441 A EP 85300441A EP 0150130 A2 EP0150130 A2 EP 0150130A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- vessel
- conduit
- oil
- tap changer
- switch
- 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.)
- Withdrawn
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/08—Cooling; Ventilating
- H01F27/10—Liquid cooling
- H01F27/12—Oil cooling
- H01F27/14—Expansion chambers; Oil conservators; Gas cushions; Arrangements for purifying, drying, or filling
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F29/00—Variable transformers or inductances not covered by group H01F21/00
- H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
- H01F29/025—Constructional details of transformers or reactors with tapping on coil or windings
-
- 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
- H01H2009/0055—Oil filters for tap change devices
Definitions
- This invention relates to an on-load tap changer, and more particularly, to an oil-filtering system for an oil-filled on-load tap changer.
- a diverter switch of a conventional on-load tap changer is basically a switch for switching a load current of a transformer to a preselected tap by the tap selector at no current.
- the diverter switch is enclosed within a vessel filled with an electrically insulating oil.
- the insulating oil is gradually polluted and degraded as it is decomposed to form foreign matters such as carbon and sludge by the electric arc upon each tap change, thereby degrading the electrically insulating properties.
- the on-load tap changer for use with a high-voltage transformer is provided with an oil filter unit, which is a kind of a filter with a pump in it, and the insulating oil is filtered through the oil filter unit once a day as is well known in the art.
- the conduit connecting the vessel for the diverter switch and the oil filter unit is arranged such that polluted oil at the bottom of the vessel of the tap-changer is suctioned into the conduit and pumped through the filter element of the oil filter unit to return to the upper portion of the tap changer vessel.
- the diverter switch is typically suspended from the top of the transformer tank, and the oil filter unit is positioned outside the transformer tank and placed on the same level as the transformer tank.
- the suction conduit from which the oil enters for filtering is typically constructed and incorporated as one of the parts of the tap changer vessel, the conduit rises from the bottom portion of the vessel along its length and extends outwardly through the upper portion of the vessel which is secured to the top of the transformer tank.
- the vessel is suspended from the top plate of the transformer tank, the vessel is usually positioned at a higher level than is the oil filter unit.
- the conventional on-load tap changer as above constructed has the following disadvantages.
- an object of the present invention is to provide an on-load tap changer which is free from the above-mentioned drawback.
- Another object of the present invention is to provide an on-load tap changer which is free from the risk that most of the electrically insulating oil can flow out from the tap changer system.
- a further object of the present invention is to provide an on-load tap changer which is free from the risk that the level of insulating oil can fall due to an oil leak, thus exposing the interrupting unit of the tap changer.
- an on-load tap changer of the present invention comprises a switch such as a diverter switch or a selector switch including an arc interrupting unit, a vessel containing the switch, an electrically insulating oil disposed within said vessel, and a closed oil passage loop.
- the oil passage loop includes an oil conduit having an opening at the bottom portion of the interior of the vessel, extending through the upper portion of the vessel, passing through a level lower than the vessel and connected to the top portion of the vessel.
- the oil conduit has formed therein a small hole at a position higher than the interrupting unit, the hole being inside of the vessel.
- the hole has a diameter sufficiently smaller than the inner diameter of the conduit for permitting most of the insulating oil supplied into the oil filter unit to be supplied from the inlet opening of the conduit at the bottom portion of the vessel rather than the upper portion of the vessel.
- the tap changer 10 comprises a hermetic vessel 16 within which a changer-over switch 18 and an arc interrupter unit 20 are enclosed.
- the vessel 16 has an upper portion 22 and a lower portion 24 in communication with each other.
- the upper portion 22 of the vessel 16 is placed on the top plate 15 of the transformer housing 14 and the lower portion 24 of the vessel 16 is suspended into the interior of the transformer housing 14.
- the diverter switch 18 and the current interrupting unit 20 are disposed within the lower portion 24 of the vessel 16. Therefore, although they are positioned within the transformer housing 14, they are isolated by the wall of the vessel 16 from the interior of the transformer housing 14.
- the tap-changer vessel 16 is substantially filled with an electrically insulating oil 26 in order to promote the quick extinction of the arc generated during the tap changing.
- a conservater 28 connected to a breezer 30 by a conduit 32 is connected to the upper portion 22 of the tap-changer vessel 16 through a conduit 34.
- the tap changer 10 also comprises an oil filter unit 36 which includes a pump and a filter element. It is seen that the bottom wall of the oil filter unit 36 is positioned at the same level as the bottom wall of the transformer housing 14 and therefore the oil filter unit 36 is positioned at a lower level than the tap changer l0 which is positioned at the upper portion of the transformer housing 14.
- the inlet of the oil filter unit 36 is connected to the bottom portion of the tap changer vessel 16 by a conduit 38 having an inlet 40 at the bottom portion inside the tap changer vessel 16.
- the conduit 38 has the shape of an inverted "U". This is because the tap changer 10 is typically designed as an assembled unit with at least part of the conduit 38 incorporated into the vessel 16 and it is not desirable to design the walls of the vessel 16 and the transformer housing 14 to be penetrated by the conduit 38.
- the outlet of the oil filter unit 36 is connected to the upper portion 22 of the tap changer vessel 16 through a second conduit 42.
- a closed oil passage loop composed of the vessel 16, the inverted-U shaped conduit 38, the oil filter unit 36, and the second conduit 42 is formed.
- the inverted U-shaped conduit 38 has formed therein a small air breezing hole 44 at its top portion.
- the small hole 44 communicates the inside of the conduit 38 to the interior of the upper portion 22 of the tap changer vessel 16.
- the small hole 44 is designed to exhibit a very high flow resistance against the insulating oil 26 flowing therethrough as compared to the flow resistance in the section of the conduit 38 between the inlet opening 40 and the small hole 44.
- the small hole 44 has a very small diameter compared to the inside diameter of the conduit 38.
- the pump (not shown) in the oil filter unit 36 is energized to suction the insulating oil 26 in the bottom portion of the tap changer vessel 16 from the inlet opening 40.
- the small hole 44 formed in the wall of the conduit 38 is sufficiently small compared to the inside diameter of the conduit 38, the flow resistance of the small hole 44 is very high compared to the flow resistance of the flow path in the conduit 38 through the inlet opening 40. Therefore, most of the insulating oil 26 supplied into the oil filter unit 36 is supplied from the inlet opening 40 at the bottom of the tap changer vessel 16 rather than from the upper portion 22 of the vessel 16.
- the oil 26 supplied through the conduit 38 to the oil filter unit 36 passes through the filter element (not shown) of the oil filter unit 36 to be cleaned.
- the filtered oil 26 is returned to the upper portion 22 of the vessel 16 and descend to the bottom portion of the vessel 16.
- the insulating oil 26 recirculates through the closed oil passage loop composed of the vessel 16, the first conduit 38, the oil filter unit 36, and the second conduit 42.
- the insulating oil 26 within the tap changer vessel 16 flows out from the inlet opening 40 of the conduit 38 through the conduit 38 and from the leak in the oil filter unit 36. As the oil continues to leak, the insulating oil 26 is emptied first from the conservator 28, and then the level of the insulating oil 26 within the upper portion 22 of the tap changer vessel 16 gradually decreases.
- the oil conduit has formed therein a small hole at a position higher than the interrupting unit, and the hole has a diameter sufficiently smaller than the inner diameter of the conduit. Therefore, the level of the insulating oil cannot become lower than the arc interrupting unit, preventing accidents such as short-circuit between taps.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transformer Cooling (AREA)
- Housings And Mounting Of Transformers (AREA)
Abstract
Description
- This invention relates to an on-load tap changer, and more particularly, to an oil-filtering system for an oil-filled on-load tap changer.
- A diverter switch of a conventional on-load tap changer is basically a switch for switching a load current of a transformer to a preselected tap by the tap selector at no current. In order to facilitate the extinguishing of an electric arc generated at the time of current commutation, the diverter switch is enclosed within a vessel filled with an electrically insulating oil. The insulating oil is gradually polluted and degraded as it is decomposed to form foreign matters such as carbon and sludge by the electric arc upon each tap change, thereby degrading the electrically insulating properties. Therefore, the on-load tap changer for use with a high-voltage transformer is provided with an oil filter unit, which is a kind of a filter with a pump in it, and the insulating oil is filtered through the oil filter unit once a day as is well known in the art.
- The conduit connecting the vessel for the diverter switch and the oil filter unit is arranged such that polluted oil at the bottom of the vessel of the tap-changer is suctioned into the conduit and pumped through the filter element of the oil filter unit to return to the upper portion of the tap changer vessel. Since the diverter switch is typically suspended from the top of the transformer tank, and the oil filter unit is positioned outside the transformer tank and placed on the same level as the transformer tank. Also, since the suction conduit from which the oil enters for filtering is typically constructed and incorporated as one of the parts of the tap changer vessel, the conduit rises from the bottom portion of the vessel along its length and extends outwardly through the upper portion of the vessel which is secured to the top of the transformer tank. Furthermore, since the vessel is suspended from the top plate of the transformer tank, the vessel is usually positioned at a higher level than is the oil filter unit.
- The conventional on-load tap changer as above constructed has the following disadvantages.
- When insulating oil leaks from the filter element or the pump of the oil filter unit, the insulating oil within the conduits and the vessel leaks out and the oil level within the vessel falls. This lowering of the insulating oil continues until the oil level reaches the level at the inlet opening of the piping because the conduit has an inverted U-shape which causes the U-shaped conduit to function as a siphon conduit. Therefore, the oil leakage from the oil filter unit may cause most of the insulating oil within the tap-changer vessel to flow outside of the system. If the oil level becomes lower than the current interrupting unit of the diverter switch, then the arc will not be extinguished, leading to a short-circuit between the taps.
- Accordingly, an object of the present invention is to provide an on-load tap changer which is free from the above-mentioned drawback.
- Another object of the present invention is to provide an on-load tap changer which is free from the risk that most of the electrically insulating oil can flow out from the tap changer system.
- A further object of the present invention is to provide an on-load tap changer which is free from the risk that the level of insulating oil can fall due to an oil leak, thus exposing the interrupting unit of the tap changer.
- With the above objects in view, an on-load tap changer of the present invention comprises a switch such as a diverter switch or a selector switch including an arc interrupting unit, a vessel containing the switch, an electrically insulating oil disposed within said vessel, and a closed oil passage loop. The oil passage loop includes an oil conduit having an opening at the bottom portion of the interior of the vessel, extending through the upper portion of the vessel, passing through a level lower than the vessel and connected to the top portion of the vessel. The oil conduit has formed therein a small hole at a position higher than the interrupting unit, the hole being inside of the vessel. The hole has a diameter sufficiently smaller than the inner diameter of the conduit for permitting most of the insulating oil supplied into the oil filter unit to be supplied from the inlet opening of the conduit at the bottom portion of the vessel rather than the upper portion of the vessel.
- The invention will become more readily apparent from the following detailed description of the preferred embodiment of the present invention and the sole figure, which is a diagramatic view of an on-load tap changer constructed in accordance with the present invention.
- An on-
load tap changer 10 of the present invention is illustrated in the figure as being incorporated into anelectrical power transformer 12 having ahermetic housing 14. Thetap changer 10 comprises ahermetic vessel 16 within which a changer-over switch 18 and anarc interrupter unit 20 are enclosed. Thevessel 16 has anupper portion 22 and alower portion 24 in communication with each other. Theupper portion 22 of thevessel 16 is placed on thetop plate 15 of thetransformer housing 14 and thelower portion 24 of thevessel 16 is suspended into the interior of thetransformer housing 14. Thediverter switch 18 and thecurrent interrupting unit 20 are disposed within thelower portion 24 of thevessel 16. Therefore, although they are positioned within thetransformer housing 14, they are isolated by the wall of thevessel 16 from the interior of thetransformer housing 14. - The tap-
changer vessel 16 is substantially filled with an electrically insulatingoil 26 in order to promote the quick extinction of the arc generated during the tap changing. In order to absorb volumetric expansion of the insulatingoil 26 due to temperature changes, aconservater 28 connected to abreezer 30 by aconduit 32 is connected to theupper portion 22 of the tap-changer vessel 16 through aconduit 34. Thetap changer 10 also comprises anoil filter unit 36 which includes a pump and a filter element. It is seen that the bottom wall of theoil filter unit 36 is positioned at the same level as the bottom wall of thetransformer housing 14 and therefore theoil filter unit 36 is positioned at a lower level than the tap changer l0 which is positioned at the upper portion of thetransformer housing 14. - The inlet of the
oil filter unit 36 is connected to the bottom portion of thetap changer vessel 16 by aconduit 38 having aninlet 40 at the bottom portion inside thetap changer vessel 16. Theconduit 38 has the shape of an inverted "U". This is because thetap changer 10 is typically designed as an assembled unit with at least part of theconduit 38 incorporated into thevessel 16 and it is not desirable to design the walls of thevessel 16 and thetransformer housing 14 to be penetrated by theconduit 38. The outlet of theoil filter unit 36 is connected to theupper portion 22 of thetap changer vessel 16 through asecond conduit 42. Thus, a closed oil passage loop composed of thevessel 16, the inverted-U shapedconduit 38, theoil filter unit 36, and thesecond conduit 42 is formed. - According to the present invention, the inverted U-shaped
conduit 38 has formed therein a smallair breezing hole 44 at its top portion. Thesmall hole 44 communicates the inside of theconduit 38 to the interior of theupper portion 22 of thetap changer vessel 16. Thesmall hole 44 is designed to exhibit a very high flow resistance against the insulatingoil 26 flowing therethrough as compared to the flow resistance in the section of theconduit 38 between the inlet opening 40 and thesmall hole 44. In the illustrated embodiment, thesmall hole 44 has a very small diameter compared to the inside diameter of theconduit 38. - In order to clean the insulating
oil 26 of thetap changer 10, the pump (not shown) in theoil filter unit 36 is energized to suction the insulatingoil 26 in the bottom portion of thetap changer vessel 16 from the inlet opening 40. It is to be noted that, since thesmall hole 44 formed in the wall of theconduit 38 is sufficiently small compared to the inside diameter of theconduit 38, the flow resistance of thesmall hole 44 is very high compared to the flow resistance of the flow path in theconduit 38 through the inlet opening 40. Therefore, most of the insulatingoil 26 supplied into theoil filter unit 36 is supplied from the inlet opening 40 at the bottom of thetap changer vessel 16 rather than from theupper portion 22 of thevessel 16. Theoil 26 supplied through theconduit 38 to theoil filter unit 36 passes through the filter element (not shown) of theoil filter unit 36 to be cleaned. The filteredoil 26 is returned to theupper portion 22 of thevessel 16 and descend to the bottom portion of thevessel 16. Thus, the insulatingoil 26 recirculates through the closed oil passage loop composed of thevessel 16, thefirst conduit 38, theoil filter unit 36, and thesecond conduit 42. When the insulatingoil 26 has been cleaned, the pump is deenergized. - If an oil leak occurs in the
oil filter unit 36 which is lower than the bottom of thetap changer vessel 16, the insulatingoil 26 within thetap changer vessel 16 flows out from the inlet opening 40 of theconduit 38 through theconduit 38 and from the leak in theoil filter unit 36. As the oil continues to leak, the insulatingoil 26 is emptied first from theconservator 28, and then the level of the insulatingoil 26 within theupper portion 22 of thetap changer vessel 16 gradually decreases. When the oil level in theupper portion 22 of thetap changer vessel 16 reaches thesmall hole 44 in theconduit 36, air introduced within thevessel 16 from thebreezer 30 flows into thesmall hole 44, preventing further lowering of the oil level in thetap changer vessel 16 because the insulatingoil 26 in theupper portion 22 and thelower portion 24 of thevessel 16 is trapped in thevessel 16. Theoil 26 within the section of theconduit 38 to the left of thesmall hole 44 and the oil in theoil filter unit 36 flow out through the leak in thefilter unit 36. Therefore, even when an oil leak occurs in theoil filter unit 36, the insulatingoil 26 around thearc interrupting unit 20 in the vessel is maintained. - As has been described, according to the present invention, the oil conduit has formed therein a small hole at a position higher than the interrupting unit, and the hole has a diameter sufficiently smaller than the inner diameter of the conduit. Therefore, the level of the insulating oil cannot become lower than the arc interrupting unit, preventing accidents such as short-circuit between taps.
- While the present invention has been described in terms of a tap changer of a particular type, the invention is equally applicable to on-load tap changers of other types such as a tap selector switch which has the functions of both a tap selector and a diverter switch.
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8516/84 | 1984-01-24 | ||
JP851684U JPS60119724U (en) | 1984-01-24 | 1984-01-24 | Tap switching device under load |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0150130A2 true EP0150130A2 (en) | 1985-07-31 |
EP0150130A3 EP0150130A3 (en) | 1986-01-29 |
Family
ID=11695303
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85300441A Withdrawn EP0150130A3 (en) | 1984-01-24 | 1985-01-23 | On-load tap changer |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0150130A3 (en) |
JP (1) | JPS60119724U (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104051136A (en) * | 2013-03-15 | 2014-09-17 | 叶松伟 | On-load tap changer of built-in type online oil filter |
CN113909205A (en) * | 2021-11-15 | 2022-01-11 | 广西电网有限责任公司贵港供电局 | Ultrasonic wave filtering and washing device for on-load tap-changer |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61141110A (en) * | 1984-12-14 | 1986-06-28 | Toshiba Corp | On-load tap changer |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1009319A (en) * | 1963-08-19 | 1965-11-10 | Shinji Nakazawa | Conservator for oil-immersed transformers |
DE3240724A1 (en) * | 1981-11-05 | 1983-05-11 | Mitsubishi Denki K.K., Tokyo | TRANSFORMER ARRANGEMENT |
-
1984
- 1984-01-24 JP JP851684U patent/JPS60119724U/en active Granted
-
1985
- 1985-01-23 EP EP85300441A patent/EP0150130A3/en not_active Withdrawn
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1009319A (en) * | 1963-08-19 | 1965-11-10 | Shinji Nakazawa | Conservator for oil-immersed transformers |
DE3240724A1 (en) * | 1981-11-05 | 1983-05-11 | Mitsubishi Denki K.K., Tokyo | TRANSFORMER ARRANGEMENT |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN104051136A (en) * | 2013-03-15 | 2014-09-17 | 叶松伟 | On-load tap changer of built-in type online oil filter |
CN113909205A (en) * | 2021-11-15 | 2022-01-11 | 广西电网有限责任公司贵港供电局 | Ultrasonic wave filtering and washing device for on-load tap-changer |
Also Published As
Publication number | Publication date |
---|---|
JPS60119724U (en) | 1985-08-13 |
JPH0311867Y2 (en) | 1991-03-20 |
EP0150130A3 (en) | 1986-01-29 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
RU2470402C2 (en) | Vacuum diverter switch for tap changer | |
EP0957496A3 (en) | Power and/or distribution transformer equipped with on-load tap-changer | |
US3605798A (en) | Water level controls for steam tables and the like | |
EP0150130A2 (en) | On-load tap changer | |
EP0150132B1 (en) | On-load tap changer | |
EA199900657A2 (en) | Immersed transformer self-protected by a device including a circuit breaker and fuses | |
US2509935A (en) | Protective means for electrical instrumentalities | |
JPH0311868Y2 (en) | ||
US3161745A (en) | Displaceable plunger mercury switch | |
US3475693A (en) | Electrical apparatus having fuse and insulated and sealed electrical connections | |
JPS61141110A (en) | On-load tap changer | |
CN208157215U (en) | The fuel tank of buried combined transformer in power transmission and transformation system | |
CN116457912B (en) | On-load tap changer | |
JP2513579Y2 (en) | Load tap changer | |
JPS61141108A (en) | On-load tap changer | |
KR102703868B1 (en) | On-road tap changer | |
KR100587958B1 (en) | Oil filter purifier for transformer | |
CN216849572U (en) | Transformer with independent switch oil chamber | |
JPH09219320A (en) | Tap change-over transformer for load | |
SU1059632A1 (en) | Protective device | |
JPH0878249A (en) | On-load tap changer | |
US3244845A (en) | Liquid metal transfer switch | |
JPS5788710A (en) | On-load tap changer | |
US1517636A (en) | Electric contact device working with a liquid, especially mercury | |
JPS61148806A (en) | On-load tap changer |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): BE DE FR GB |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Designated state(s): BE DE FR GB |
|
17P | Request for examination filed |
Effective date: 19860314 |
|
17Q | First examination report despatched |
Effective date: 19870217 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19870630 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: SOKAI, KATSUJI Inventor name: FURUKAWA, KAZUYA |