JP2012023262A - Drying method of oil-filled electric apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drying method of an oil-filled electric apparatus capable of drying apparatus contents of an oil-filled electric apparatus and improving insulation characteristics and insulation life.SOLUTION: The drying method of an oil-filled electric apparatus comprises processes of: drawing a mineral oil 5a in a tank 1; oiling instead ester oil and so on 5b having high saturated water-content; moving water in an insulator of apparatus contents 2 to the ester oil and so on 5b by heating and circulating by an insulation oil circulation system 16; drawing ester oil and so on 5b; and oiling again a mineral oil drawn, deaerated, and treated with filtration before.

Description

  The present invention relates to a method for drying the contents of an oil-filled electrical device.

  Whether or not an oil-filled electrical device such as a transformer can withstand an overload operation is determined by performing a gas analysis in insulating oil filled in the oil-filled electrical device. As a result of gas analysis in oil, if more flammable gas is generated in the insulating oil than the criterion, it is determined that the oil-filled electrical device cannot withstand overload operation.

  Further, even when no flammable gas is generated in the insulating oil, it is determined that the overload operation cannot be performed if the moisture content in the insulating material constituting the equipment exceeds the allowable value. The amount of water in the insulator is estimated by measuring the amount of water in the insulating oil.

  If the moisture content in the insulating paper, which is an insulator, is less than 1%, it is judged that overload operation is possible, and if the moisture content in the insulation paper is 1% or more, overload operation is impossible. It is judged that. When it is determined that the overload operation is impossible, it is necessary to adjust the moisture content in the insulating paper to be less than 1% by dehydrating the insulator in the device.

  As the dehydration process, there is known a method of heating and drying the contents of the equipment using Joule heat generated by energizing the windings constituting the contents of the equipment with the equipment contents completed.

  According to this heating method, there is an advantage that drying of the vicinity of the winding can be realized in a short time, but Joule heat hardly reaches the portion away from the winding, and it is separated from the vicinity of the winding. There was a drawback that uneven drying occurred between the portions.

  In order to solve this problem, a method of drying by moving the moisture in the equipment to the insulating oil has been proposed (see Patent Document 1).

JP-A-63-12118

  According to this method, by storing the heated equipment content in a tank and immersing it in the insulation oil that has been kept warm, it is possible to utilize the fact that the vapor pressure of the moisture in the equipment content is significantly higher than that of the insulation oil side. The water content can be moved to the insulating oil side in a relatively short time, and the equipment content can be dried evenly.

  Moreover, moisture absorption of the apparatus content after a drying process can be suppressed by immersing the apparatus content with a new insulating oil immediately after a drying process.

  However, the drying method described in Patent Document 1 previously energizes the windings in the equipment so that the temperature of the windings is 100 ° C. or higher, and when the insulating oil is injected into the tank, the insulating oil is added at 40 ° C. It must be kept at around 50 ° C, and after injecting the insulation oil into the tank, it continues to energize the windings to keep the contents of the equipment at a high temperature, thereby transferring moisture to the insulation oil. There is a drawback that it is necessary to suppress a decrease in the action, and it takes much time and labor.

  Also, the insulating oil to be injected into the tank is usually mineral oil, and since the saturated moisture content is small, the migration rate of moisture from the equipment contents to the insulating oil is slow and the migration amount is also small. In addition, the contents of the equipment must be dried while the equipment is stopped, and the drying time is inevitably limited due to restrictions on the time during which a power failure is possible.

  In addition, almost no moisture in the press board that constitutes the contents of the equipment can be removed, and when the amount of moisture in the insulating oil is measured after a predetermined time has elapsed after practicing the drying method, before the drying treatment is performed. There was a drawback that the amount of water in the oil was about the same.

  Therefore, in order to solve the above-mentioned problem, the present invention uses an insulating oil having a high saturated moisture amount for the movement of moisture from the contents of the equipment, and efficiently circulates the insulating oil by hot oil circulation. It is an object of the present invention to provide a method for drying an oil-filled electrical device that can uniformly dry the contents of the device.

  In the first aspect of the present invention, after extracting the mineral oil used as the insulating oil of the oil-filled electrical equipment, the insulating oil having a higher saturated moisture content than the mineral oil is injected, and the insulating oil having the higher saturated moisture content is injected. By circulating the hot oil, the water content in the insulator in the device is transferred to the insulating oil having a high saturated water content, and the device content is dried.

  In the invention according to claim 2, after extracting the mineral oil used as the insulating oil of the oil-filled electrical equipment, the insulating oil having a higher saturated water content than the mineral oil is injected, and the insulating oil having the higher saturated water content is injected. By circulating the hot oil, the moisture in the insulation of the equipment is transferred to the insulating oil having a high saturated moisture content, and the extracted mineral oil is purified through a degassing process and a filtration step, and then again the saturated moisture content. It is characterized in that the contents of the equipment are dried by exchanging high insulating oil and mineral oil.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the insulating oil having a high saturated water content is ester oil or silicone oil.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the insulating oil having a high saturated moisture amount is heated to a viscosity equivalent to mineral oil by a heating means prior to hot oil circulation. By reducing the temperature, it is possible to achieve efficient drying in the hot oil circulation.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, when the mineral oil or the insulating oil having a high saturated water content is extracted, the oil-filled electrical device is dried via a desiccant. It is characterized by supplying air.

  According to invention of Claim 1, after extracting mineral oil used as insulating oil from oil-filled electrical equipment, oil oil is injected by injecting insulating oil having a saturated water content higher than that of mineral oil and thermally circulating. Moisture in the insulator that makes up the equipment contents of the input electrical equipment can be transferred to the insulating oil side with a high saturation moisture content in a short time, and the moisture can be removed from the insulator in the equipment contents without unevenness. Can be dried.

  According to the second aspect of the present invention, the mineral oil extracted from the oil-filled electrical device is reliably purified by passing through a degassing process and a filtration step, thereby insulating the oil-filled electrical device with a high saturated water content. After extracting the oil, the extracted mineral oil can be reused by pouring the oil again into the oil-filled electrical device.

  In addition, according to the invention of claim 2, after drying the equipment content of the oil-filled electrical equipment, by replacing the ester oil or the like again with mineral oil, by the ester oil or the like having a high viscosity and a high coefficient of thermal expansion, It is possible to reliably prevent the cooling performance from being lowered during the operation of the oil-filled electrical device or the diaphragm of the conservator from being damaged as the temperature rises.

  According to the third aspect of the present invention, an ester oil or a silicone oil that is easily available as an insulating oil having a high saturated moisture content is used, and even if the ester oil or the like is mixed with mineral oil, oil-filled electricity The influence on the electrical characteristics of the device can be eliminated.

  According to the invention described in claim 4, by heating the insulating oil having a high saturated water content prior to circulating the hot oil, the viscosity of the insulating oil can be reduced to a viscosity equivalent to that of mineral oil. It is possible to promote moisture transfer and deaeration from the insulator constituting the equipment contents to the insulating oil.

  According to invention of Claim 5, when extracting mineral oil or ester oil etc. from oil-filled electrical equipment, by supplying dry air inside oil-filled electrical equipment via a desiccant, Without contacting the insulating oil with air containing moisture, the oil can be drained satisfactorily using the supply pressure of the dry air.

It is a front view of the oil-filled electrical equipment to which the drying method of the present invention is applied. (A) is a figure explaining the process of extracting insulating oil from the said oil-filled electrical equipment, (b) It is a figure explaining the process of pouring insulating oil into the said oil-filled electrical equipment. It is a figure explaining the hot oil circulation by the drying method of this invention. It is a graph showing the relationship between the drying time by the drying method of this invention, and the moisture content in insulating paper. It is a figure explaining the oil extraction operation | work of the said insulating oil.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a front view showing an example of an oil-filled electrical device to which a drying method according to the present invention is applied. In FIG. 1, A is an oil-filled transformer, and 1 indicates a tank of the oil-filled transformer A.

  Reference numeral 2 denotes a transformer main body (hereinafter referred to as an equipment content) formed by assembling the iron core 3 and the winding 4 housed in the tank 1.

  Reference numeral 5 denotes an insulating oil poured into the tank 1, and 6 denotes an insulating oil which is installed at the upper part of the tank 1 and prevents the air from coming into direct contact with the insulating oil 5 in the tank 1 by an internal diaphragm 7. 5 and a conservator that prevents the insulators constituting the device contents 2 from being oxidized by contact with moisture in the air and from deteriorating electrical characteristics.

  Reference numeral 8 denotes a hygroscopic respirator attached to the upper part of the conservator 6 via a vent pipe 9 to prevent deterioration of the insulating oil 5 and the diaphragm 9 in the conservator 6 and the tank 1.

  In the oil-filled transformer A configured as described above, when the use of the device A is continued, an insulator such as insulating paper constituting the device content 2 is deteriorated with generation of water. The generated water stays in the insulator almost without moving to the insulating oil 5 side.

  The water remaining in the insulator accelerates the deterioration of the insulator and further promotes the deterioration of the insulator. As the deterioration of the insulator progresses and the water in the insulator increases, voids (voids) are generated during overload operation, and the risk of partial discharge leading to dielectric breakdown increases.

  In order to avoid such a danger, the drying method according to the present invention is applied. Hereinafter, the drying method of the oil-filled electrical apparatus according to the present invention will be described. First, as shown in FIG. 1, a valve (hereinafter referred to as an oil removal valve) 10 attached to the lower part of the tank 1 of the oil-filled transformer A is opened, and an insulating oil (mineral oil) 5 a filled in the tank 1. Drain the oil.

  At this time, the mineral oil 5a in the tank 1 is drained to the outside of the tank 1 through the oil drain valve 10 by its own weight immediately after the opening of the oil drain valve 10. Oil is not removed from the oil removal valve 10 to the outside of the tank 1 by its own weight.

  Therefore, a gas supply device 12 that supplies dry air and nitrogen at high pressure is connected to an oil supply valve 11 provided in the upper part of the tank 1, and the pressure of the supply gas is utilized by supplying these high pressure gases into the tank 1. Thus, the mineral oil 5a is efficiently extracted from the tank 1 to the outside of the tank 1 through the oil extraction valve 10.

  As described above, the reason why dry air and nitrogen are supplied into the tank 1 is to prevent the mineral oil 5a in the tank 1 from coming into contact with moisture in the air.

  The mineral oil 5a withdrawn through the oil removal valve 10 is degassed and filtered by the degassing device 13 shown in FIG. 2A, and is stored in the mineral oil storage tank 14 in a purified state. Next, as shown in FIG. 1B, a drying insulating oil storage tank 15 in which insulating oil 5b having a high saturated water content (hereinafter referred to as ester oil or the like) 5b such as ester oil or silicone oil is stored in advance is shown in FIG. Instead of the gas supply device 12, the oil supply transformer 11 is connected via an oil supply valve 11.

  Then, ester oil or the like 5b is injected from the tank 15 into the tank 1 of the oil-filled transformer A. When ester oil or the like 5b is injected into the tank 1, the connection state between the tank 15 and the tank 1 is released, and then the insulating oil circulation device 16 shown in FIG. 3 is connected to the tank 1.

  The insulating oil circulation device 16 circulates the ester oil or the like 5b in the tank 1 through the oil pipe 17, and includes a heater (not shown) for heating the ester oil or the like 5b inside. Then, hot oil is circulated in the tank 1 through the oil passage pipe 17 while the ester oil or the like 5b is heated to a predetermined temperature by the heater.

  When the ester oil or the like 5b is heated to a predetermined temperature by the heater, its viscosity rises to a viscosity equivalent to that of mineral oil, and moisture transfer from the insulator constituting the equipment contents 2 to the ester oil or the like 5b side, that is, a drying treatment Can be promoted. As described above, the ester oil 5b has a much higher saturated water content than the mineral oil 5a, so that the water generated in the insulating material such as the insulating paper used for the equipment contents 2 is ester oil or the like. It is possible to shift well to the 5b side.

  Thereby, the apparatus content 2 can be dried in a short time without unevenness, and the risk of the occurrence of voids (voids) during overload can be reduced.

  Next, the connection between the tank 1 and the insulating oil circulation device 16 is released, and the ester oil 5b from which water has been transferred is removed from the oil removal valve 10 shown in FIG. At this time, as in the case of extracting the mineral oil 5a from the tank 1, the gas supply device 12 is connected to the oil supply valve 11 and high pressure gas such as dry air or nitrogen is supplied from the device 12 into the tank 1. Thus, the ester oil 5b is removed from the tank 1 through the oil removal valve 10.

  The extracted ester oil 5b is degassed by the degassing device 13 and stored in the insulating oil storage tank 15 for drying, as shown in FIG.

  On the other hand, the mineral oil 5a previously degassed and stored in the mineral oil storage tank 14 connects the mineral oil storage tank 14 to the oil supply valve 11 of the tank 1 as shown in FIG. It is returned to the tank 1 of A.

  The reason why the insulating oil 5 in the tank 1 is returned to the mineral oil 5a again from the ester oil 5b from which moisture has been transferred from the equipment content 2 is because of the difference in properties such as viscosity between the ester oil 5b and the mineral oil 5a. In order to prevent the cooling of the transformer from becoming insufficient and to prevent the deterioration of the insulator that constitutes the transformer A due to the increase in the operating temperature, or to surely prevent the mechanical parts such as the pump from being adversely affected. is there.

  By applying the above drying method, it is possible to satisfactorily dry the device contents 2 including an insulator in which moisture is generated due to aging. As a result, the generation of voids (voids) during overload operation can be reliably suppressed, and the risk of partial discharge leading to dielectric breakdown can be eliminated.

  Here, the moisture content of the ester oil 5b or the like to be poured into the tank 1 is desirably 50 [ppm] or less, but if it is up to 200 [ppm], it can be sufficiently utilized for the above-described hot oil circulation.

  FIG. 4 is a graph showing the transition of the moisture content in paper and the moisture content in insulating oil to which the drying method of the present invention is applied. As is apparent from this figure, the moisture content in the insulating paper decreases with the elapse of the drying time, and conversely, the moisture content in the ester oil increases. This indicates that the moisture in the insulating paper surely moved to the ester oil 5b side by the drying method.

  FIG. 5 shows another embodiment in the case where mineral oil 5a, ester oil, etc. 5b are extracted from the tank 1 through an oil extraction valve 10. As described above, when the mineral oil 5a or ester oil 5b is extracted from the tank 1, as shown in FIG. 1, by supplying dry air, nitrogen or the like from the high-pressure gas supply device 12 into the tank 1, The insulating oil 5 can be extracted from the tank 1.

  However, in this embodiment, instead of using dry air or nitrogen, air is supplied into the tank 1 from the high-pressure gas supply device 12 via the container 18 for the hygroscopic agent. The air supplied from the high-pressure gas supply device 12 is surely absorbed by a moisture absorbent such as silica gel contained in the storage container 18 by the moisture storage container 18 to generate dry air. 1 will be supplied.

  As a result, as in the first embodiment shown in FIG. 1, the mineral oil 5a or ester oil 5b filled in the tank 1 does not come into contact with moisture in the air, and the pressure of the dry air supplied into the tank 1 The oil can be reliably discharged out of the tank 1 through the oil removal valve 10 attached to the lower part of the tank 1.

  In addition, it is 1st Example that the extracted insulating oil 5 is deaerated by the deaeration processing device 13 shown in FIG. 2A and stored in the mineral oil storage tank 14 or the drying insulating oil storage tank 15. It is the same.

  In the drying method of the present invention, it is noted that the mineral oil 5a, the ester oil 5b and the like are extracted from the tank 1 by taking a sufficient time. When the oil is poured in a state where the mineral oil 5a and the ester oil 5b remain in the tank 1, the mineral oil 5a and the ester oil 5b are mixed to change the physical properties such as the viscosity according to the mixing ratio, thereby preventing this. It is necessary. Therefore, it is important to prevent the mixing and suppress the property change of the insulating oil as much as possible by ensuring a sufficient oil removal time.

  In addition, in the said Example, although the sealing-type oil-filled electrical apparatus A (refer FIG.1, 5) provided with the conservator 6 was demonstrated as an example, the drying method of this invention is not limited to this, What is called, Naturally, even an open type oil-filled electrical device or a sealed oil-filled electrical device can be used for a nitrogen-filled type or a rubber bag type oil-filled electrical device.

  As described above, according to the method for drying an oil-filled electrical device of the present invention, when newly manufacturing an oil-filled electrical device, the content of the device is surely dried, and the insulation characteristics and insulation life of the transformer are reduced. Can be improved.

  In addition, when moisture is generated in the insulator of the electrical equipment due to aging, the equipment content is surely dried to prevent voids (voids) during overload, resulting in dielectric breakdown. The risk of partial discharge can be eliminated.

  It can be used for drying oil-filled electrical equipment that can dry the contents of the oil-filled electrical equipment and improve the insulation characteristics and insulation life.

DESCRIPTION OF SYMBOLS 1 Tank 2 Equipment contents 3 Iron core 4 Winding 5 Insulating oil 5a Mineral oil 5b Ester oil etc. 6 Conservator 7 Diaphragm 8 Hygroscopic respirator 9 Venting pipe 10 Oil removal valve 11 Oil supply valve 12 High pressure gas supply device 13 Deaeration processing device 14 Mineral oil oil storage Tank 15 Insulating oil storage tank for drying 16 Insulating oil circulation device 17 Oil passage pipe 18 Hygroscopic container A Oil-filled transformer

Claims (5)

  After extracting mineral oil used as insulating oil for oil-filled electrical equipment, injecting insulating oil having a higher saturated moisture content than mineral oil, and circulating the insulating oil having a higher saturated moisture content in hot oil A method for drying an oil-filled electrical device, wherein the moisture in the insulator is transferred to insulating oil having a high saturated moisture content to dry the contents of the device.   After extracting mineral oil used as insulating oil for oil-filled electrical equipment, injecting insulating oil having a higher saturated moisture content than mineral oil, and circulating the insulating oil having a higher saturated moisture content in hot oil After the moisture in the insulator is transferred to the high-saturated insulating oil, the extracted mineral oil is cleaned through degassing and filtration, and then the high-saturated insulating oil and mineral oil are replaced again. A method for drying an oil-filled electrical device, characterized in that the content of the device is dried.   The method for drying an oil-filled electrical device according to claim 1, wherein the insulating oil having a high saturated water content is ester oil or silicone oil.   2. The insulating oil having a high saturated water content achieves efficient drying in the hot oil circulation by reducing the viscosity to a viscosity equivalent to mineral oil by a heating means prior to the hot oil circulation. The drying method of the oil-filled electrical equipment according to any one of claims 3 to 4.   The oil filling according to any one of claims 1 to 4, wherein dry air is supplied into the oil-filled electrical device via a desiccant when the mineral oil or the insulating oil having a high saturated water content is drained. How to dry electrical equipment.

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