JPH0410725B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to an insulating liquid that cools the windings by an insulating tank that accommodates the windings, and a tank that houses the iron core and the like to which the insulating tank is filled. The present invention relates to a liquid-cooled gas-insulated induction electric appliance in which an insulating gas is partitioned, and in particular to a structure that enables prevention and detection of a drop in liquid level due to leakage of an insulating tank.

[Prior art and its problems]

In recent years, there has been an increasing demand for induction electric appliances to be nonflammable and flame retardant, mainly from the perspective of disaster prevention.
Insulating gases and fluorocarbons, such as SF ₆ gas,
So-called evaporative cooling type induction electric appliances, which are replaced with condensable insulating liquids such as fluorocarbons, are attracting attention. On the other hand, there is a desire to increase the voltage of such non-flammable induction electric appliances, and by utilizing the low viscosity of the above-mentioned cooling medium, the cooling medium is forced to circulate within the windings at high speed to perform sensible heat cooling. It is known that the deterioration of electrical resistance performance due to vapor bubbles of the cooling medium is prevented by this method.

FIG. 2 is a schematic side sectional view showing an example of a conventional liquid-cooled gas insulated transformer. Inside the tank 1 containing the insulating gas 5, there is an inner cylinder 4A attached to the leg of the iron core 2, and an outer cylinder 4A attached to the leg of the iron core 2. A transformer body is housed, which includes an insulating tank 4 consisting of a cylinder 4B, a flat ring-shaped cover plate 4C, and a bottom plate 4D, and a winding 3 housed in the insulating tank 4 and consisting of an inner winding 3A and an outer winding 3B. has been done. In addition, a forced circulation passage consisting of circulation passages 9A, 9B, a pump 8A, and a liquid cooler 7 is provided above and below the insulation tank 4. The winding 3 is configured to be cooled by sensible heat by forced circulation of the insulating liquid 6 within the winding. By the way, the insulation tank 4 can be formed liquid-tight using a fiber-reinforced plastic board or pipe, but it is possible to form it using a laminated board of high-density pressboard or a pipe, which has been used in many oil-immersed transformers. , which has the advantage of being cheaper to form; in this case, the insulating liquid 6 that has passed through the high-density pressboard leaks little by little (approximately several tens to 100 cm ³ per minute in a large capacity transformer), so the bottom of the tank 1 A leakage reservoir 11 is provided in the tank, and the accumulated leakage is removed from the leakage treatment section 1, which includes a pump 8B, piping 9C, a degassing tank 12, an exhaust pump 14, etc.
After degassing with 0, pipe 9D, pump 8
It is configured so that the flow returns to the forced circulation passage side via C. In the figure, 9E is a pipe for returning the insulating gas such as SF ₆ gas (containing the vapor of the insulating liquid) separated from the insulating liquid 6A to the tank 1, and the degassed insulating liquid 6 is returned to the insulating tank 4. By flowing, the winding 3 is sensible thermally cooled by the degassed insulating liquid 6, and the dielectric strength of the high electric field part near the winding is maintained by the insulating liquid 6 that does not contain vapor bubbles. Accordingly, it is possible to obtain a liquid-cooled gas-insulated induction electric appliance capable of increasing voltage.

However, in the transformer configured as described above, a large mechanical force may be applied to the winding due to a short circuit in the load circuit of the winding 3 or an earthquake, and the insulation tank that houses and supports the winding may be 4 is damaged by the above mechanical force, the return flow rate of the insulating liquid 6 by the leakage processing section 10 consisting of the degassing tank 14 and the pumps 8B, 8C, etc. cannot catch up with the leakage rate, and the insulating tank 4 There is a risk that the liquid level in the insulation tank will drop and lead to insulation breakdown of the windings, and even in the unlikely event that liquid leakage from the insulation tank suddenly increases, the liquid level will not drop immediately. Furthermore, it is desired to develop a technology that can detect a sudden increase in liquid leakage.

[Purpose of the invention]

The present invention was made in view of the above-mentioned situation, and
To provide a liquid-cooled gas-insulated induction electric appliance that can prevent the liquid level from lowering below a predetermined level even when liquid leakage from an insulating tank rapidly increases, and can detect and report a rapid increase in liquid leakage. With the goal.

[Key points of the invention]

The induction electric appliance of the present invention includes a leakage storage tank that is liquid-tightly connected and supported to the bottom plate of the insulation tank and formed to surround the inner and outer peripheries of the insulation tank, and a leakage storage tank that is connected to the bottom of the leakage storage tank. A liquid level detector that detects the liquid level and issues a signal, and a leak valve that communicates with the bottom of the leakage storage tank and causes leakage of less than an allowable amount to flow back to the leakage processing section. With this configuration, steady leakage from the insulating tank is directed to the reservoir at the bottom of the tank via the leak valve, and leakage that significantly exceeds this is collected in the leakage reservoir and drained onto the top of this reservoir. A drop in the liquid level is prevented by overflowing into the tank from the edge, and a rise in the liquid level in the leakage storage tank is detected by a liquid level detector connected to the tank and an abnormal liquid leakage signal is generated. It is something.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a schematic side sectional view showing an embodiment of the present invention, and the same parts as in the prior art are given the same reference numerals and detailed explanations are omitted. In the figure, the inner cylinder 24 of the insulation tank 4 is connected to the inner cylinder 24A and the outer cylinder 24B whose lower ends are liquid-tightly connected to the bottom plate 4D of the insulation tank 4.
It is a leakage storage tank defined between A and the outer cylinder 4B, and is made of a cylindrical body made of high-density pressboard, for example, and the upper edges of the outer cylinders 24A and 24B are above the upper surface of the winding 3. Preferably, it is formed so as to be located at the same level as the lid plate 4C of the insulation tank. 25 is a cylindrical level meter, the lower end of which communicates with the leakage storage tank 24 via piping 29A, and the upper end of which communicates with piping 29A.
It communicates with the insulating gas space 5 near the upper edge of the outer cylinder 24B via B. Further, the lower end of the level meter 25 is communicated with the insulating gas space 5 via a leak valve 27.
26 is a detector for detecting an increase in liquid leakage in the insulating tank 4, and a flow switch 26A that is arranged on the upper pipe 29B side of the level meter 25 and opens and closes by sensing the flow velocity or flow rate, and the operation of this flow switch 26A. A signal circuit 26 that emits an abnormal liquid leakage signal in response to
The level meter 25 and the detector 26 constitute a liquid level detector that can visually check the liquid level. Further, it is preferable that the volume of the leakage storage tank 24 is as small as possible, and in the outer cylinders 24A and 24B that define the leakage storage tank 25, the insulation layer 4 is deformed by the mechanical force applied to the winding 3. Even in such cases, it is preferable to connect and support only the lower end of the insulating tank so that the effect of deformation is not directly applied.

In the induction electric appliance configured as described above, the insulating liquid 6 that regularly leaks from the insulating tank 4 made of high-density pressboard or the like is collected in the leakage storage tank 24 and sent to the level meter side via the lower piping 29A. However, by adjusting the leak valve 27, it is recovered as a steady liquid flow 6A shown by the arrow in the figure into the tank 1, and the leakage liquid 6A accumulated in the leakage reservoir 11 is sent to the pump 8B, the degassing tank 12, the pump 8C, etc. The liquid is degassed in the leakage treatment section consisting of the pump 8A, the cooler 6, and the insulating tank 4, and the insulating tank 4 is filled with the degassed insulating liquid 6. The wire 3 is cooled by the sensible heat of the insulating liquid 6, and the high electric field area near the winding is insulated by the insulating liquid, which does not contain bubbles and has excellent electric field resistance. If the insulation tank 4 is partially deformed and damaged under the influence of the mechanical force acting on the windings, and abnormal leakage occurs that exceeds the steady leakage 6A regulated by the leak valve 27, leakage will accumulate. The liquid level in the tank 24 rises, and this rise in the liquid level can be detected visually using the level meter 25. If there is a continuous abnormal leakage or a sudden abnormal leakage, the insulating liquid accumulated in the leakage tank will flow from its upper edge and the upper pipe 29B of the liquid level detector to the insulating gas space 5 in the tank 1. This overflows, producing an abnormal liquid flow 6B indicated by an arrow in the figure. Of this abnormal liquid flow, the liquid flow passing through the upper pipe 29B is transferred to the flow switch 26.
When detected by A and the switch is activated,
An abnormal liquid leakage signal 30 is output from the signal circuit 26B. Therefore, by operating the alarm using this signal, the occurrence of abnormal liquid leakage can be immediately known. At this time, the leaked liquid is returned to the forced circulation system via the leakage processing section 10, and the liquid level in the insulation tank 4 is raised to the inner and outer cylinders 24.
Since it is regulated at the upper edge positions of A and 24B, it is possible to prevent a situation where the liquid level in the insulation tank 4 rapidly drops and an insulation accident occurs. So pump 8
It is possible to secure enough time to determine the amount of abnormal liquid leakage 6B from the discharge amount of A and trip the power supply as necessary. Note that the abnormal liquid flow detector is not limited to a flow switch, and a float switch may be provided on the liquid level detector side. In this case, the upper end of the level meter 25 is connected to the leakage storage tank. It is preferable to position it above the upper edge.

〔Effect of the invention〕

As described above, the present invention provides a leakage storage tank that is fluid-tightly connected and supported to the bottom of an insulating tank made of pressboard or the like and formed to surround the inner and outer peripheries of the insulating tank, and a leakage storage tank that communicates with the bottom of the tank. a liquid level detector that detects the liquid level of the storage tank and issues a signal; and a leak valve that communicates with the bottom of the leakage storage tank and causes leakage of less than an allowable amount to flow back to the leakage processing section. It was configured to provide As a result, steady leakage from the insulating tank is returned to the tank via the leakage storage tank and leak valve, degassed by a known leakage treatment section, and returned to the forced circulation system. The insulating tank can be easily and inexpensively formed using a material that is permeable to the insulating liquid. In addition, abnormal leakage that exceeds the steady leakage amount regulated by the leak valve will be classified as a regular leak by adjusting the leak valve, and will cause the leakage storage tank to overflow into the tank. , this can be detected by a detector and notified by emitting a signal, and the drop in the liquid level in the insulation tank can be prevented by return flow from the leakage storage tank and leakage treatment section, which is a problem with conventional technology. It is possible to provide a liquid-cooled gas-insulated induction electric appliance that can prevent an accident of dielectric breakdown of a winding due to a drop in the liquid level in an insulating tank. This configuration frees the insulating tank from the constraint that it must be extremely robust against leakage.

[Brief explanation of drawings]

FIG. 1 is a schematic side sectional view showing an embodiment of the present invention;
FIG. 2 is a side sectional view showing an example of the prior art. 1...tank, 2...iron core, 3...winding, 4...
...Insulating tank, 5...Insulating gas, 6...Insulating liquid, 7
...Liquid cooler, 8...Pump, 9...Piping, 10
...Leakage treatment section, 11...Leakage reservoir, 24...Leakage storage tank, 24A...Inner cylinder, 24B...Outer cylinder, 2
5... Level meter, 26... Detector, 26A... Flow switch, 26B... Signal circuit, 27... Leak valve, 29A, 29B... Liquid level detector piping.

Claims (1)

[Scope of Claims] 1. Condensation in which a winding installed in an insulating tank stored in a tank containing insulating gas and attached to a core leg is forced to circulate through a liquid cooler communicating with the insulating tank. The bottom part of the insulating tank is provided with a leakage treatment section that is sensible-cooled by a dielectric insulating liquid, collects and deaerates leaked liquid from the insulating tank, and flows back to the circulation path side. a leakage storage tank that is fluid-tightly coupled to the storage tank to store the leakage liquid to a predetermined level and overflow, and a liquid level that communicates with the bottom of the leakage storage tank to detect the liquid level of the storage tank and generate a signal. A liquid-cooled gas-insulated induction electric appliance, comprising: a detector; and a leak valve that communicates with the bottom of the leakage storage tank and causes leakage of less than an allowable amount to flow back to the leakage treatment section. . 2. In what is stated in claim 1,
A liquid-cooled gas-insulated induction electric appliance characterized in that an insulating tank and a leakage storage tank are made of pressboard and its molded material. 3 In what is stated in claim 1,
A liquid-cooled gas-insulated induction electric appliance characterized in that the upper edge of the leakage storage tank is located below the upper surface of the winding.