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

Definitions

• the invention is related to an insulation liquid expansion assembly for an insulation liquid tank for a high voltage coil, comprising an expansion vessel with an inlet and an outlet opening, wherein the inlet opening is foreseen to be fluidic connected with the insulation liquid tank.
• transformers, reactors, coils and other electrical devices in high voltage distribution networks for example with a rated voltage of 1 10kV or 380kV, are typically arranged within a tank filled with an electrical insulation liquid such as oil.
• an electrical insulation liquid such as oil.
• the internal insulation distances which are required to withstand the respective voltage level are reduced and the overall size of the electrical high voltage device can become reduced in an advantageous way.
• the electrical insulation liquid has the function of a cooling liquid.
• an expansion vessel is foreseen above the vessel. Thermal expansion depends for example on the actual operational losses of the high voltage device or on the thermal environmental frame conditions.
• the size of the expansion vessel is chosen in that way, that in case of minimal thermal expansion the insulation liquid tank is still full and that in case of maximum thermal expansion the expansion volume of the insulation liquid can by absorbed by the expansion vessel.
• the filling level of the expansion vessel is inbetween >0% and ⁇ 100%.
• the surface of the insulation liquid within the expansion vessel is frequently sealed against the atmosphere. Such a sealing is commonly made by means of a flexible diaphragm or a rub- ber bag mounted in the expansion vessel.
• an insulation liquid expansion assembly of the aforementioned kind is characterized by a compensation pipe which is fluidic connected at its first end with the outlet opening of the expansion vessel, a flexible gas bag which is fluidic connected to the compensation pipe so that a gas can flow from the compensation pipe into the gas bag and backwards and pressure means for applying a pressure force on the interior of the otherwise hermetically sealed compensation pipe.
• Basic idea of the invention is not to seal the surface of the insulation liquid directly within the expansion vessel, but to provide expansion means, in particular a flexible gas bag, outside the expansion vessel.
• the interior space of the insulation liquid tank, the expansion vessel and the flexible gas bag together form a hermetically sealed expandable interior space, wherein expansion takes place outside the expansion vessel by fitting the volume of the flexible gas bag.
• the interior of the hermetically sealed expandable interior space is not only filled with an insulation liquid, but also with a certain volume of a suitable gas.
• the filling of the insulation liquid tank and expansion vessel with an insulation liquid corresponds to the state of the art, wherein the remaining volume of the expandable interior space, in particular the interior space of the compensation pipe and the of the flexible gas bag, are filled with the suitable gas.
• the maximum volume of the flexible gas bag will be at least equal to the maximum differential volume of the liquid within the insulation liquid filled tank.
• the suitable gas is air. Since the whole expandable interior space is hermetically sealed no additional moisture can infiltrate therein and contaminate the insulation liquid.
• the operation pressure will be slightly over atmosphere pressure, for example some few mBar. Thus it is ensured, that the flexible gas bag can expand against atmosphere pressure.
• pressure means are foreseen at the otherwise hermetically sealed compensation pipe for applying a pressure force on the gas in the hermetically sealed expandable interior space.
• This flexible gas bag can be placed at any convenient floor level and distance to the insulation liquid tank by means of the compensation pipe, which might be made from pipes and/or hoses or the like.
• the flexible gas bag is preferably mounted inside a housing or enclosure.
• There are no certain requirements on the shape of a flexible gas bag typically a cuboid or a cylinder shape might be used.
• the insulation liquid expansion assembly comprises an insulation liquid tank for a high voltage coil, wherein the expansion vessel is arranged above the insulation liquid tank and is fluidic connected therewith.
• the insulation liquid tank and the expansion vessel are part of the assembly according to the invention.
• the inlet opening of the expansion vessel is arranged at its bottom and the outlet opening at its top. So it is ensured, that insulation liquid flowing out of the insulation liquid tank due to thermal expansion is safely guided into the expansion vessel and flows back in case of a thermal contraction.
• the pressure means of the com- pensation pipe comprise a separator liquid filled syphon which is fluidic connected therewith.
• the syphon is acting as an over pressure and vacuum protection syphon.
• the syphon will be filled with a separator liquid (not vaporizing or frizzing at operation conditions), which must not necessarily be but might be identical with the insulation liquid so that both liquids could be oil.
• the level of the separator liquid in the corre- sponding tubes or pipes defines the operation pressure of the gas filled bag. In case of higher pressure the separator liquid will be displaced by gas and the gas will be released to the atmosphere. In case of vacuum on the insulation liquid tank air can enter the insulation liquid expansion assembly.
• the insulation liquid expansion assembly can be operated with different suitable gases.
• a riser pipe is foreseen at the open outlet of the syphon.
• the maximum pressure which might be applied by the separator liquid filled syphon on the hermetically sealed interior space depends on the shape and volume of the syphon itself, the filling level of separator liquid and the riser pipe. Basically the interior volume of the preferably vertically arranged riser pipe corresponds at least to half of the volume of the separator liquid within the syphon to ensure that the separator liquid can't become popped there out under normal conditions.
• a breather in particular a silica gel breather is foreseen to become fluidic connected with the compensation pipe temporary. The expandable interior space is hermetically sealed under normal conditions.
• the breather is a dry gas device such as a silica gel breather in order to reduce moisture entering the insulation liquid expansion assembly through the breather.
• a three way cock is foreseen for the temporary connection of the breather with the compensation pipe. This enables a high flexibility for connecting or disconnecting any branch of the expandable interior space.
• the flexible gas bag is made from a foil or membrane.
• the flexible gas bag is hermetically surrounded by a further flexible gas bag, wherein means for detecting a differential pressure inbetween the interior of both gas bags are foreseen.
• the pressure detecting means might be a differential pressure relay that is be fitted to the surrounding flexible gas bag. If gas is leaking through the inner flexible gas bag a slight differential pressure will be detected.
• the maximum inner volume of the flexible gas bag is adapted to the inner volume of the expansion vessel.
• the volume of the expansion vessel is chosen in that way, that it can absorb the whole additional differential volume of the insulation liquid within the insulation liquid tank which might occur due to thermal expansion.
• the volume of the flexible gas bag is also adapted thereto.
• the flexible gas bag is arranged within an enclosure or housing.
• a suitable protection against environmental frame conditions such as snow, wind, UV radiation and the like is provided.
• a sump for collecting insulation liquid is arranged at a sink of the compensation pipe.
• a monitoring system for supervis-ing the presence of a liquid in the sump is foreseen.
• any respective fault can become detected automatically.
• a high voltage coil and/or a high voltage transformer is arranged within the insulation liquid tank wherein the tank is filled with insulation liquid such as oil. So a complete working environment is provided as part of the insulation liquid expansion assembly.
• Fig. 1 shows an exemplary first arrangement with insulation liquid expansion as- sembly
• Fig. 2 shows an exemplary second arrangement with insulation liquid expansion assembly
• Fig. 3 shows an exemplary third arrangement with insulation liquid expansion assembly.
• FIG. 1 shows an exemplary first arrangement with insulation liquid expansion assembly in a sketch 10.
• a high voltage transformer with high voltage coils 14 and a transformer core 1 6 is arranged within an insulation liquid tank 12.
• the insulation liquid tank 12 is foreseen to be filled with an insulation liquid such as oil.
• an expansion vessel 20 is arranged, which is fluidic connected therewith by a liquid pipe 18, which ends at an inlet 22 at the bottom of the expansion vessel 20.
• a compensation pipe 26 is fluidic connected thereto.
• the compensation pipe 26 is leading to a syphon 30 at its second end 28.
• the inlet 34 of a flexible gas bag 32 is fluidic connected with the compensation pipe 26, so that gas can flow from the compensa- tion pipe 26 into the flexible gas bag 32 and backwards.
• the maximum inner volume of the flexible gas bag 32 corresponds approximately to the inner volume of the expansion vessel 20.
• the syphon 30 is foreseen to be filled with a separator liquid and to apply a pressure force on the hermetically sealed interior space of the fluidic connected insulation liquid tank 12, the expansion vessel 20 and the flexible gas bag 32.
• a riser pipe 36 is foreseen in order to prevent separator liquid popping out of the syphon 30.
• a breather 38 is temporary fluidic connectable with the compensation pipe 26, so that even in case of a maintenance of the flexible gas bag 32 for example the transformer can be operated anyhow. After maintenance the connection of the breather 38 has to be closed so that the interior space is hermetically sealed again.
• a sump 42 is connected to the compensation pipe 26, so that fluid entering the compensation pipe 26 for example by a mistake during maintenance can be collected therein.
• FIG. 2 shows an exemplary comparable second arrangement with insulation liquid expansion assembly in a sketch 50.
• an insulation liquid tank 52 and an expansion vessel 58 are fluidic connected and filled with an insulation liquid 54 up to a filling level 56.
• a respective coil or transformer is not depicted in the insulation liquid tank 52 but it can be assumed to be present.
• the filling level 56 within the expansion vessel 58 is rather close to full, so only a limited amount of gas 60 is present in the top of the expansion vessel 58.
• a compensation pipe is connecting the expan- sion vessel 58 with a flexible gas bag 62 that is filled nearly up to its maximum volume with gas 64.
• FIG. 3 shows an exemplary comparable third arrangement with insulation liquid expansion assembly in a sketch 70.
• An insulation liquid tank and an expansion vessel 74 are fluidic connected and filled with an insulation liquid up to a filling level 72.
• the filling level 72 within the expansion vessel 74 is rather close to empty, so that larger amount of gas 76 is present in the top of the expansion vessel 74.
• a compensation pipe is connecting the expansion vessel 74 with a flexible gas bag 80 that is filled with only a small amount of its maximum volume with gas 80. This is an example for a very low expansion of the insulation liquid.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Housings And Mounting Of Transformers (AREA)

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Citations (4)

Family Cites Families (5)

• 2015
  • 2015-03-19 EP EP15159799.4A patent/EP3070724B1/en active Active
• 2016
  • 2016-03-11 WO PCT/EP2016/055293 patent/WO2016146525A1/en active Application Filing
  • 2016-03-11 CN CN201680028696.6A patent/CN107624195B/zh active Active

Patent Citations (4)

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