JP2007194234A - Method for preventing leakage of insulation oil at terminal portion of power apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To replace an electric apparatus and to repair a terminal portion during scheduled inspection by providing a method for preventing leakage of oil to the terminal portion quickly and easily without interrupting conduction of electricity to the electric apparatus thereby preventing oil leakage temporarily. <P>SOLUTION: In the method for preventing leakage of insulation oil at the terminal portion of a power apparatus, the terminal portion of the power apparatus is sealed by filling the terminal box 81 of the power apparatus internally filled with insulation oil with transparent and electrically insulating curing resin 86, and the terminal portion of the power apparatus is sealed by enclosing the terminal box 81 by a transparent plastic plate 82'. Preferably, the curing resin 86 is a polyurethane based resin curing in semisolid state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for preventing leakage of insulating oil into a terminal portion in a power device, for example, a current transformer for an instrument, in which the insulating oil is filled therein, and in particular, insulation to the terminal portion. The present invention relates to a preferable method as an emergency measure when an oil leak is detected.

In power equipment such as an instrument current transformer that requires internal insulation, the interior is often filled with insulating oil to ensure the insulation.
For example, an insulator-type current transformer as shown in FIG. 1 converts a circuit current into a small current at a power plant and is installed for the purpose of measurement and circuit protection. The upper container 2 includes a fixed upper container 2 and a lower container 3 attached to the lower portion of the soot tube 1, and a primary terminal 4 is provided in the upper container 2. A primary winding 5 connected to the primary terminal 4 is provided in the lower container 3. Is wound around an annular iron core 6, and a secondary winding 7 is also wound around the iron core 6, and the secondary winding 7 is connected to a secondary terminal 8 on the side wall of the lower container 3. In addition, the insulating tube 9 is filled in the soot tube 1, the upper container 2, and the lower container 3. The secondary terminal 8 is accommodated in a cylindrical terminal box 81 attached to the side wall of the lower container 3, and the outer opening of the terminal box 81 is closed by bolting the lid plate 82. . In the present specification, a portion including the secondary terminal 8, the terminal box 81, and the cover plate 82 is referred to as a terminal portion.

When the insulator-type current transformer is for high voltage, it becomes a considerably long object, and the pressure applied to the oil-tight structure portion of the secondary terminal 8 reaches 1 kg / cm ² even with the head pressure alone. Therefore, the insulating oil 9 may leak from the secondary terminal 6 of such a current transformer to the terminal portion. Therefore, conventionally, a structure of a current transformer that prevents leakage of insulating oil has been proposed (see Patent Document 1).

However, in spite of the conventional improvement, if such a current transformer is used for many years, it is inevitable that the insulating oil will ooze out and leak out to the terminal part, and if oil leaks, it will lead to environmental pollution, Moreover, when the amount of oil leakage increases, dielectric breakdown occurs.
Therefore, in order to prevent these, it is desired to repair the terminal part as soon as possible or to replace the current transformer.

  When the present inventors tried repairing the oil leakage part with putty at first, the oil leakage could not be stopped completely. In order to completely stop the oil leakage, the terminal part must be completely repaired, and in order to perform this repair, the insulating oil must be extracted once. Even if the current transformer must be stopped and the current transformer is replaced, the power transmission of the power plant still has to be stopped, so it takes a lot of labor to perform these operations during normal operation of the power plant. With loss.

Japanese Utility Model Publication No. 57-197630

  The object of the present invention is to provide a method that can quickly and easily prevent oil leakage to the terminal part without stopping energization of the electrical equipment, thereby preventing oil leakage on an emergency basis during periodic inspections. The purpose is to be able to replace electrical equipment and repair terminal parts.

  According to the present invention, the object is to fill a terminal box of a power device filled with insulating oil with a transparent electrically insulating curable resin and to seal the terminal box with a transparent plastic plate. This is achieved by an insulating oil leakage prevention method for a terminal portion of a power device, wherein the terminal portion of the power device is sealed. As the transparent insulating curable resin, a polyurethane-based resin that is cured in a gel form is preferable because it is excellent in oil resistance, sealing property, and the like.

  According to a preferred embodiment of the present invention, the present invention includes a step of covering the opening of the terminal box with a transparent plastic plate having an injection opening, and then applying the liquid curable resin before curing to the injection. It is carried out by injecting into the terminal box from the inlet and curing it, and closing the inlet.

  According to the present invention, the terminal box is filled with a liquid transparent electrically insulating curable resin, and the terminal box is sealed with a transparent plastic plate to seal the terminal portion. Without stopping energization of the terminal, not only can oil leakage to the terminal portion be easily prevented, but also the progress of oil leakage at the terminal portion can be monitored through a transparent plastic plate and resin. Therefore, not only is it suitable for preventing leakage of oil to the terminal part as soon as possible during periodic inspection while the electrical equipment is energized, but also the presence or absence of leakage can be visually monitored until the periodic inspection. Therefore, an accident due to dielectric breakdown can be prevented in advance, which is preferable from the viewpoint of safety. Moreover, this invention can also be used for the purpose of prevention of the oil leak of a terminal part.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. In the following example, an example in which the present invention is applied to an insulator-type current transformer will be described. However, the present invention can be similarly applied to other electric devices in which insulating oil may leak out to a terminal portion.

  2 and 3 are enlarged views of the terminal portion of the apparatus of FIG. 1, FIG. 2 is a front view, and FIG. 3 is a side sectional view. As described above, the terminal portion includes the secondary terminal 8, the terminal box 81, and the lid plate 82. The secondary terminals 8 are provided through the substrate 80 that is oil-tightly attached to the opening of the side wall of the lower container 3. Usually, a total of eight secondary terminals 8 are provided on the substrate 80. The end of the secondary winding 7 is connected to the inner side of the lower container 3 of the secondary terminal 8 (see FIG. 1), and a conductor 83 connected to an instrument such as an ammeter is connected to the outer side of the lower container 3 of the secondary terminal 8. It is connected.

  As described above, when the current transformer is used for many years, the insulating oil 9 may ooze out from the periphery of the secondary terminal 8 and the like, and may leak into the terminal portion. In such a case, the lid plate 82 is removed, and instead of the lid plate 82, a transparent plastic plate 82 'having the same shape with the inlet 84 opened is attached. The plastic plate 82 ′ can be attached by using a bolt 85 that has fixed the lid plate 82. As the plastic plate 82 ', an acrylic plate or the like is preferably used. At this time, if necessary, the periphery of the secondary terminal 8 from which the insulating oil 9 has oozed may be repaired with a putty or the like.

  Then, as shown in FIG. 3A, the liquid transparent electrically insulating curable resin 86 before curing is filled and cured from the injection port 84. In this case, the curable resin 86 is liquid and fluid when injected from the injection port 84, but needs to be cured as it is injected and left. The curable resin 86 is preferably a resin that is cured in a semi-solid state such as jelly, rubber, or gel at the time of curing and exhibits tackiness. In addition, the curable resin 86 is preferably one that does not shrink during curing from the viewpoint of hermeticity. Furthermore, the curable resin 86 preferably has oil resistance against insulating oil. In addition, the dielectric breakdown strength (measured by JIS K 6911) of the curable resin 86 is preferably 30 kV / mm or more, more preferably 37 kV / mm or more, and its water absorption (measured by JIS K 6911) is preferably 0.05% or less, more preferably 0.03% or less. If the water absorption rate is too high, the insulation performance deteriorates with time, which is not preferable. As the curable resin 86, a commercially available product such as Debcon SU (trade name: 2-component polyurethane resin manufactured by ITW Industry Co., Ltd.) can be used.

  As shown in FIG. 3B, after filling the terminal portion with the curable resin 86, the injection port 84 of the plastic plate 82 'is filled with the putty 87 and closed. As the putty 87, a commercially available product can be used, but the same material as the curable resin 86 may be used.

  As described above, since the terminal portion is filled with the curable resin 86 and sealed with the plastic plate 82 ′, the entire terminal portion is sealed with resin, and leakage of insulating oil from the lower container 3 to the terminal portion is prevented. It can be easily prevented, and since the curable resin 86 and the plastic plate 82 ′ are transparent, it is possible to visually monitor the state of oil leakage prevention, so it is possible to prevent power outage accidents due to current breaker breakdown. It is suitable as an emergency measure until the regular inspection, and can be used as a preventive measure even when no oil leakage occurs.

  The insulating oil leakage prevention method of the present invention can be used as a countermeasure against oil leakage in power equipment at a power plant or the like.

It is a partially broken side view which shows the outline of the insulator type current transformer which can implement the method of this invention. It is a front view which shows the terminal part of the current transformer of FIG. 1 which implemented the method of this invention. (A) is a sectional side view of the terminal part of FIG. 2 which shows the state of the implementation process of the method of this invention. (B) is a sectional side view of the terminal part of FIG. 2 shown in a state where the method of the present invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Steel pipe, 2 ... Upper container, 3 ... Lower container, 4 ... Primary terminal, 5 ... Primary winding, 6 ... Iron core, 7 ... Secondary winding, 8 ... Secondary terminal, 9 ... Insulating oil, 81 ... Terminal Box, 82 ... lid plate, 82 '... transparent plastic plate, 83 ... conducting wire, 84 ... inlet, 85 ... bolt, 86 ... curable resin, 87 ... putty.

Claims (3)

A terminal box (81) of a power device, which is filled with insulating oil (9) inside, is filled with a transparent electrically insulating curable resin (86), and the terminal box (81) is filled with a transparent plastic plate ( 82 ′), sealing the terminal part of the electric power device by sealing it, insulating oil leakage prevention method of the terminal part of the electric power device. The method according to claim 1, wherein the transparent insulating curable resin (86) is a polyurethane-based resin that is cured in a semi-solid state. After covering the opening of the terminal box (81) using a transparent plastic plate (82 ') having an opening (84), the liquid curable resin (86) before curing is injected into the inlet. 3. A method according to claim 1 or 2, characterized in that it is injected into the terminal box (81) from (84) and cured, and the inlet (84) is closed.

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