EP2985773A1 - Laststufenschalter für Trockentransformator und Trockentransformator damit - Google Patents

Laststufenschalter für Trockentransformator und Trockentransformator damit Download PDF

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Publication number
EP2985773A1
EP2985773A1 EP14002816.8A EP14002816A EP2985773A1 EP 2985773 A1 EP2985773 A1 EP 2985773A1 EP 14002816 A EP14002816 A EP 14002816A EP 2985773 A1 EP2985773 A1 EP 2985773A1
Authority
EP
European Patent Office
Prior art keywords
changer
load tap
tap
hollow casing
insulation
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Withdrawn
Application number
EP14002816.8A
Other languages
English (en)
French (fr)
Inventor
Benjamin Weber
Dr. Jens Tepper
Dr. Martin Carlen
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.)
ABB Schweiz AG
Original Assignee
ABB Technology AG
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 ABB Technology AG filed Critical ABB Technology AG
Priority to EP14002816.8A priority Critical patent/EP2985773A1/de
Priority to PCT/EP2015/063526 priority patent/WO2016023660A1/en
Publication of EP2985773A1 publication Critical patent/EP2985773A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • H01H9/0016—Contact arrangements for tap changers
    • 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
    • H01H9/0016—Contact arrangements for tap changers
    • H01H2009/0022—Mounting of the fixed contacts or taps on cylindrical wall of oil vessel containing the tap changer; Details of screening
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H50/00—Details of electromagnetic relays
    • H01H50/02—Bases; Casings; Covers
    • H01H50/023—Details concerning sealing, e.g. sealing casing with resin
    • H01H2050/025—Details concerning sealing, e.g. sealing casing with resin containing inert or dielectric gasses, e.g. SF6, for arc prevention or arc extinction
    • 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
    • H01H33/021—Use of solid insulating compounds resistant to the contacting fluid dielectrics and their decomposition products, e.g. to SF6

Definitions

  • the invention is related to an on-load tap-changer for dry transformers, comprising an electric insulating hollow casing extending around a virtual axis, wherein several electric contact sections are foreseen along the inner surface of the hollow cylinder, which are electrically joined through the wall of the hollow casing and a selector contact in the inner of the casing which is rotatable around the virtual axis and that's radial outer end is selectively connectable with one of the contact sections by a respective rotation.
  • the invention is also related to a transformer with an on-load tap-changer.
  • a tap-changer is a selector switch which enables the selective electrical connection of one output with one of several contact sections.
  • An on-load tap-changer has the ability to switch under load current.
  • the contact sections are arranged along a circular path wherein the selector contact is rotatable around a virtual axis in the center of the circular path.
  • a selector contact which is moveable in axial direction along axially arranged contact sections is a suitable embodiment of an on-load tap-changer.
  • On-load tap-changers are used to adapt the transmission ratio of a power transformer in distribution networks within certain limits.
  • taps of the transformer winding are electrically connected with respective contact sections of a tap-changer, wherein a certain voltage difference inbetween the respective connector sections is present, which might be at around +/- 10% of the rated voltage of the transformer over all taps.
  • the connector sections are typically foreseen on the inner surface of an electric insulating hollow cylinder.
  • the electrical insulation inbetween adjacent connector sections has to be foreseen to withstand a respective voltage difference. The highest voltage difference will rise inbetween first and last tap, which are adjacent due to the circular arrangement.
  • Oil transformers are known for voltages of 380kV and higher and for a rated power of some 100MVA for example.
  • As an oil transformer itself also a tap changer for an oil transformer is flooded with the insulation medium oil, which enables a compactor design due to the reduced required insulation distance inbetween adjacent connector sections.
  • Dry transformers avoid the insulation medium oil due to reasons of improved security or easier handling. Dry transformers are typically known for voltages up to 36kV or 72,5kV with a rated power of for example some MVA. Due to this - at least in relation - not as high voltage the required insulation distances inbetween the different selector contacts within the tap-changer are not as high so that the size of a respective oil-free on-load tap-changer is still within acceptable limits. Anyhow, the rated voltage for dry transformers is expected to increase in the future, for example to 110kV.
  • Objective of the invention is to provide an on-load tap-changer for dry transformers with a reduced size, especially with respect to an increased rated voltage.
  • an on-load tap-changer for dry transformers of the aforementioned kind is characterized in that the inner space of the hollow casing is hermetically sealed and filled with a preferably pressured insulating gas.
  • the casing is hollow cylinder like.
  • Basic idea of the invention is to reduce the size and the insulation distances within the electric insulating hollow casing by sealing it hermetically and filling it with a preferably pressurized insulating gas that's electrical insulation ability is better than the insulation ability of air.
  • a dry transformer wherein the size of the tap-changer is reduced in an advantageous way respectively the tap-changer is enabled to withstand a higher rated voltage.
  • the insulation gas is SF6.
  • This type of insulation gas is known for insulating switchgear-substations within an energy distribution system and is proven technology.
  • a barrier-shield is foreseen in the radial space inbetween radial inner and radial outer end of the selector contact, which is rotatable together with the selector contact.
  • Barriers are known means to improve the insulation ability within or around an electrical high voltage device.
  • a fixed standard barrier is subject to collisions with the rotatable selector contact.
  • the idea of this embodiment consists in making a barrier rotatable together with the selector switch to exclude any collision.
  • a rotatable barrier-shield is also suitable for a tap-changer, which is not hermetically sealed and which is not filled with a pressured insulating gas.
  • respective cables are foreseen to electrically connect the contact sections from the radial outer side of the hollow cylinder, wherein at least some of the cables comprise a respective surrounding outer insulation at least at their respective connected end.
  • a cable is foreseen as electrical conductor leading for example from the taps of a transformer to the connector sections of the tap-changer.
  • the creeping distance inbetween adjacent cables has significant influence on the insulation ability inbetween them.
  • a respective surrounding outer insulation at the respective connected end on the tap-changer side of a cable increases the insulation ability inbetween adjacent cables in an advantageous way. Further increase could be gained by insulation rips or the like.
  • a front end of the surrounding insulation is hermetically connected with the outer surface of the hollow cylinder. This might be done for example by use of suitable glue or an epoxy resin.
  • the at least one cable comprises at least in sections a screen around its surrounding insulation.
  • the electrical potential on the outer surface of the cable insulation can be set to a defined value by connecting it with a defined voltage potential.
  • the insulation behavior is more reproducible and reliable therewith.
  • the screen of the cable is electrically connected with one of those contact sections which are not connected with the respective cable.
  • the electrical potential of the screen of the cable is different than the electrical potential of the respective cable itself in case that the tap-changer is in the operating state. This is useful to reduce the potential of the screen compared to the potential of the inner cable, thus the insulation requirements on the outer surface of the hollow casing are reduced due to reduced voltage differences inbetween the respective screens of the respective cables. A part of the voltage is insulated by the surrounding insulation of the cable in such a case.
  • the first tab is assumed to have the lowest output voltage and the last tap to have the highest output voltage. Assuming further a sequential and circular arrangement of the contact sections within the hollow cylinder, the contact sections for first and last tap will be adjacent each to each other and the insulation inbetween the respective cables will be stressed by the maximum voltage difference inbetween first and last tap. Since the at least one medium tap will have a voltage-level inbetween the voltage of the first and the last tap, a connection of at least one of the screens of the cables for first or last tab with one of the at least one medium taps will reduce the voltage stress on the outer side of the hollow casing in an advantageous way. In case of several medium taps preferably this tap which is electrically exactly inbetween the first and last tap should be connected.
  • Figure 1 shows a first exemplary on-load tap-changer 10 in a cross-sectional view.
  • An electric insulating hollow casing 12 in this case a hollow cylinder for example made from glass fiber epoxy, is extending around and along a virtual axis 14.
  • Several exemplary contact sections 16, 18, 20, 22 are arranged along a circular path on the inner surface of the electric insulating hollow casing 12.
  • An inner pole 27 with a radial oriented selector contact 24 with radial inner end 26 and radial outer end 28 is rotatable around the virtual axis 14. By rotation of the inner pole 27 the radial outer end 28 of the selector contact 26 is selectively connectable with one of the contact sections 16, 18, 20, 22.
  • the contact section 22 is electrically connected with a cable 32 that is surrounded by an outer insulation 34.
  • the insulation 34 increases the insulation ability inbetween adjacent cables 32 on the outer side of the electric insulating hollow casing 12.
  • the cable 32 is leading to a tap of a non-shown transformer winding and also the other contact sections 16, 18, 20 are supposed to be connected with further taps of the non-shown transformer winding.
  • FIG. 2 shows a second exemplary on-load tap-changer 40 in a cross-sectional view.
  • a cable 42 is leading to the outer surface of an electric insulating hollow casing 50.
  • the cable 42 is surrounded by an outer insulation 44, which itself is surrounded by an electrical screen 46, wherein on the outer surface of the screen 46 a further insulation layer 48 is foreseen.
  • the screen 46 is electrically connected 54 with a further cable leading to another contact section.
  • the electrical potential of the shield corresponds to the potential of the further cable 56.
  • both components 44, 50 are hermetically connected as indicated with the dotted ellipse 52. This can be done for example by use of suitable glue or an epoxy resin or the like.
  • Figure 3 shows a third exemplary on-load tap-changer 60 in a 3D view.
  • An electric insulating hollow casing 62 is arranged around a virtual axis 64 and shown in a three dimensional view.
  • Front end covers 66 are foreseen at both axial ends to ensure, that the inner space of the electric insulating hollow casing 62 is hermetically sealed, so that pressured insulating gas, which is filled therein, can't leak therefrom.
  • the pressured insulating gas enables a smaller design of the on-load tap-changer 60.
  • a cable 68 indicates an electrical connection to a not shown tap of a transformer, wherein several cables of this kind are supposed to be foreseen.
  • a rotation shaft 70 around the virtual axis 64 is foreseen to rotate a selector contact in the inner of the electric insulating hollow cylinder.
  • Figure 4 shows a fourth exemplary on-load tap-changer 80 in a cross-sectional view.
  • a selector contact 86 is rotatable together with a barrier shield 82 around a virtual axis, so that the selector contact is selectively connectable with one of several contact sections.
  • Rips 84 increase the creeping distance along the surface of the barrier shield 82.
  • the barrier improves the insulation behavior in the inner of the hollow cylinder, so that either the tap-changer 80 can be operated with a higher voltage or its size can be reduced in an advantageous way.
EP14002816.8A 2014-08-13 2014-08-13 Laststufenschalter für Trockentransformator und Trockentransformator damit Withdrawn EP2985773A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP14002816.8A EP2985773A1 (de) 2014-08-13 2014-08-13 Laststufenschalter für Trockentransformator und Trockentransformator damit
PCT/EP2015/063526 WO2016023660A1 (en) 2014-08-13 2015-06-17 On-load tap-changer for dry transformers and dry transformer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP14002816.8A EP2985773A1 (de) 2014-08-13 2014-08-13 Laststufenschalter für Trockentransformator und Trockentransformator damit

Publications (1)

Publication Number Publication Date
EP2985773A1 true EP2985773A1 (de) 2016-02-17

Family

ID=51352383

Family Applications (1)

Application Number Title Priority Date Filing Date
EP14002816.8A Withdrawn EP2985773A1 (de) 2014-08-13 2014-08-13 Laststufenschalter für Trockentransformator und Trockentransformator damit

Country Status (2)

Country Link
EP (1) EP2985773A1 (de)
WO (1) WO2016023660A1 (de)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2835311A1 (de) * 1978-08-11 1980-02-28 Transformatoren Union Ag Lastumschalter fuer transformatoren
US5661280A (en) * 1995-08-02 1997-08-26 Abb Power T&D Company Inc. Combination of a gas-filled interrupter and oil-filled transformer
CN202307477U (zh) * 2011-11-09 2012-07-04 陕西汉中变压器有限责任公司 智能集成高低压同步有载调容分接开关
EP2530693A1 (de) * 2011-05-31 2012-12-05 ABB Technology Ltd Stufenschalter
EP2637186A1 (de) * 2012-03-07 2013-09-11 ABB Technology Ltd Stufenwähler und Verfahren zur Montage eines Stufenwählers

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2835311A1 (de) * 1978-08-11 1980-02-28 Transformatoren Union Ag Lastumschalter fuer transformatoren
US5661280A (en) * 1995-08-02 1997-08-26 Abb Power T&D Company Inc. Combination of a gas-filled interrupter and oil-filled transformer
EP2530693A1 (de) * 2011-05-31 2012-12-05 ABB Technology Ltd Stufenschalter
CN202307477U (zh) * 2011-11-09 2012-07-04 陕西汉中变压器有限责任公司 智能集成高低压同步有载调容分接开关
EP2637186A1 (de) * 2012-03-07 2013-09-11 ABB Technology Ltd Stufenwähler und Verfahren zur Montage eines Stufenwählers

Also Published As

Publication number Publication date
WO2016023660A1 (en) 2016-02-18

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