JPH1027724A - Power capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power capacitor with which a serious accident can be prevented by a method wherein the occurrence of an abnormal state inside a capacitor is easily and quickly discovered. SOLUTION: A capacitor element is housed in a rectangular parallelepiped case where insulating oil is filled. Mounting members 4 and 6, having tapered screws 4a and 6a, are provided on the upper cover 1a of the case 1. Fixtures 5 and 7, which can be screwed into the mounting members 4a and 6a, are fixed to a highest temperature indicator 2 and a hollow tube 3, and the temperature indicator 2 and the hollow tube 3 are vertically fixed to the upper cover 1a of the case 1 by screwing the fixture 5 into the mounting member 4. The scale part of the temperature indicator 2 is exposed to outside the case 1, and a temperature sensing part 2b is located in the insulating oil in the case 1. The side of the blocked part 2a of the hollow tube 3 is exposed, and its opened part 2b side is in the case 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor in which a wound capacitor element is housed in a case together with insulating oil, and more particularly to a power capacitor used in a power converter.

[0002]

2. Description of the Related Art A power capacitor is used in a power converter such as an inverter for converting DC power into AC power.
Plays an important role. In general power capacitors, in order to satisfy a predetermined rating, a plurality of capacitor elements are connected in series and parallel to form a capacitor content, and this capacitor content is housed in a case filled with insulating oil. Things.

Among such power capacitors, those used in inverters include commutation capacitors and A
This is a capacitor for the C filter. The commutation capacitor and the AC filter capacitor are usually configured as SH capacitors and NH capacitors.

[0004] The SH capacitor uses a capacitor element in which a vapor-deposited metallized paper and an organic film are superposed or wound, or uses a capacitor element in which only a vapor-deposited metallized film is wound, and has a self-healing effect. Have. With self-healing action, because the electrode is an ultra-thin metal deposited on the dielectric, even if there is dielectric breakdown at the weakest point in the dielectric, only the periphery of the weak point scatters at that moment, This is the function of maintaining the function as a capacitor.

On the other hand, an NH capacitor uses a capacitor element formed by laminating a combination of a capacitor thin paper and an organic film or a dielectric film consisting of only an organic film and a metal electrode foil such as an aluminum foil. Has no self-healing effect.

When the above-described SH capacitor or NH capacitor is used in a high-frequency power supply as a commutation capacitor or an AC filter capacitor, a high-frequency current flows through the capacitor element. Then, heat is generated due to internal loss, and the temperature of the capacitor body increases. Since the high-temperature side usage limit that general capacitors can be used continuously is set at the time of design as the maximum operating temperature, if the temperature rise approaches this maximum operating temperature, the life of the capacitor will be affected . For example, even in the SH capacitor described above, if the temperature rises over a long period of use, internal insulation deterioration and tan δ increase.

To cope with this, regular maintenance,
When performing an inspection, it is necessary to easily and quickly determine the occurrence of an abnormality inside the capacitor by measuring the temperature of the capacitor and prevent a serious accident from occurring. Therefore, several types of capacitors having a structure in which a temperature rise can be visually confirmed have been conventionally proposed. For example, there are a type in which a temperature measuring device is arranged around a capacitor to enable a temperature measurement in a space around the capacitor, and a type in which a thermocouple is mounted on a case surface to measure a case surface temperature.

Further, a thermo paint or a thermo label is pasted on the surface of the capacitor, and a change in the color of the thermo paint or the thermo label can be used to determine the deterioration temperature of the capacitor by knowing the surface temperature of the capacitor. Proposed. Japanese Patent Application Laid-Open No. Hei 5-343252 proposes an improved type of capacitor to which thermopaint is applied.

[0009]

However, the capacitor capable of measuring the temperature as described above has the following problems. In other words, when measuring the temperature of the space around the capacitor, the temperature of the capacitor itself is not directly measured, so it is susceptible to the outside temperature, etc.
Errors easily occur in measured values. In particular, when there is another heating element near the capacitor, the heat generation affects the temperature measuring device, so that an error occurs in the determination of the capacitor temperature.

Next, when the thermocouple is mounted, the work of wiring the thermocouple is required, and the mounting is troublesome. In order to continuously perform temperature measurement, it is necessary to continuously attach a thermocouple, but this is practically difficult.

Further, in the case of using a thermopaint or a thermolabel, similarly to the case of measuring the temperature of the space around the capacitor, it is easily affected by the heating element near the capacitor. The inverter device has a service life of 10 to 1
Since it is usually 5 years or more, it is necessary to wipe off dirt on the thermopaint or thermolabel during that time. In particular, in the case of damage or weathering, replacement work and repainting work must be performed, and maintenance is troublesome.

Further, the above prior arts all measure the temperature outside the capacitor, so that it is not possible to accurately grasp abnormalities caused by temperature rise inside the capacitor or generation of gas from insulating oil. For this reason, it is not easy to quickly determine the occurrence of an abnormality and prevent an accident from occurring.

The present invention has been proposed to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a power capacitor capable of easily and quickly detecting occurrence of an abnormality in a capacitor and preventing a serious accident from occurring.

[0014]

In order to achieve the above object, according to the present invention, a capacitor element formed by winding an overlapping dielectric layer and electrode layer is filled with insulating oil. In the power capacitor housed in the case, a maximum thermometer is provided in the case,
A scale portion of the highest thermometer is exposed to the outside of the case, and a temperature sensing part of the highest thermometer is in insulating oil inside the case.

According to the first aspect of the present invention, the temperature sensing portion of the highest thermometer is inserted into the insulating oil inside the case and the scale portion is exposed to the outside of the case. Thus, the temperature inside the capacitor can be accurately measured. Therefore, by comparing the measured temperature with a preset maximum use temperature, the deterioration state inside the capacitor can be easily and accurately grasped.

According to a second aspect of the present invention, in a power capacitor in which a capacitor element formed by winding an overlapping dielectric layer and electrode layer is housed in a case filled with insulating oil, one end is closed. A hollow tube having the other end opened is provided in the case, a closed end side of the hollow tube is exposed to the outside of the case, and an open end side of the hollow tube is inserted into the case. It is characterized in that the insulating oil is provided to be able to flow in from the opening end.

According to the second aspect of the present invention, when dielectric breakdown and healing are repeated with the progress of deterioration due to long-term use of the capacitor, the gas absorption capacity of the insulating oil is saturated. Then, the generated gas is released and rises as a bubble into the hollow tube, so that the gas can be visually recognized from the closed end side of the hollow tube exposed to the outside. Therefore, it is possible to easily and quickly determine that the deterioration abnormality is progressing inside the capacitor.

According to a third aspect of the present invention, there is provided a power capacitor in which a capacitor element formed by winding an overlapping dielectric layer and electrode layer is housed in a case filled with insulating oil. A maximum thermometer is provided, a scale portion of the maximum thermometer is exposed to the outside of the case, a temperature sensing portion of the maximum thermometer is in insulating oil inside the case, one end is closed, and the other end is closed. An open hollow tube is provided in the case, a closed end side of the hollow tube is exposed to the outside of the case, and an open end side of the hollow tube is inserted into the case. Is provided so as to be able to flow therethrough.

According to the third aspect of the present invention, the temperature rise inside the capacitor can be accurately grasped by the scale portion of the maximum thermometer, and the abnormal deterioration can be confirmed by visually observing the closed end side of the hollow tube. You can judge that it is progressing. Therefore, it is possible to more accurately and accurately grasp the internal deterioration state.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment corresponding to the first to third aspects of the present invention will be described below with reference to FIGS.

(1) Configuration of Embodiment First, the configuration of this embodiment will be described. That is, FIG.
As shown in FIG. 1, a capacitor element configured as an SH capacitor or an NH capacitor is accommodated in a rectangular parallelepiped case 1 filled with insulating oil. A plurality of terminals 1 b are provided on the upper lid 1 a of the case 1.
Is connected to a lead derived from the capacitor element. A top thermometer 2 is provided on the top lid 1a of the case 1.
And the hollow tube 3 are inserted vertically with one end exposed.

Among them, the maximum thermometer 2 is suitable for knowing the maximum value thereafter since the index stops at the maximum temperature position when the temperature rises within a certain time.
The highest thermometer 2 is silver-plated on its surface and then tin-plated. As shown in FIG. 2 (b), the scale portion 2a is exposed to the outside of the case 1 and the temperature-sensitive portion 2b is
Inside the insulating oil. In addition, case 1 of the maximum thermometer 2
Is configured as follows. That is, as shown in FIGS. 2A and 2B, the mounting member 4 having the tapered screw 4 a is provided on the upper lid 1 a of the case 1. An attachment 5 that can be screwed into the mounting member 4 a is fixed to the maximum thermometer 2, and the attachment 5 is screwed into the tapered screw 4 to fix the maximum thermometer 2 to the case 1.

On the other hand, the hollow tube 3 is made of a transparent tempered glass, and as shown in FIGS.
a, the other end is formed as an opening 3b. As shown in FIG. 4, the hollow tube 3 has a configuration in which the closed portion 3a is exposed and the opening 3b is located inside the case 1, so that the insulating oil can flow through the opening 3b. . Further, the fixed portion of the hollow tube 3 to the case 1 is configured as follows, similarly to the maximum thermometer 2 described above. That is, the upper cover 1a of the case 1 is provided with the mounting member 6 having the tapered screw 6a. Then, the mounting member 6a
Is fixed to the hollow tube 3 and the mounting tool 7 is screwed into the tapered screw 6a,
The hollow tube 3 is fixed to the case 1.

(2) Operation of the Embodiment The operation of the embodiment having the above configuration is as follows. That is, when the capacitor is used for a long period of time, the withstand voltage of the insulating oil filled in the case 1 decreases due to a long-term stress due to a rise in temperature or application of a surge. Then, partial dielectric breakdown occurs inside the capacitor element. At this time, the insulating oil is decomposed due to local dielectric breakdown, and gas is generated.
For example, in the case of an SH capacitor, healing occurs,
The deposited metal film is scattered and gasified, and tan δ
(Dielectric tangent) increases and insulation deterioration proceeds.

Further, the temperature inside the capacitor rises,
As the deterioration proceeds, the scale portion 2a of the maximum thermometer 2 exposed to the outside indicates the maximum use temperature, so that it can be determined that the temperature is abnormal. Further, when dielectric breakdown and healing due to long-term deterioration progress are repeated, the amount of generated gas exceeds the gas absorption amount of the insulating oil, and the insulating oil becomes saturated. Then, air bubbles are generated in the insulating oil, flow from the opening 3b of the hollow tube 3, and float up to the closed portion 3a at the upper end. Therefore, the closed portion 3a of the hollow tube 3 exposed to the outside
By visually recognizing the side, it can be determined that the deterioration abnormality is progressing.

(3) Effects of the Embodiment The effects of the present embodiment as described above are as follows.
That is, a temperature rise or deterioration abnormality inside the capacitor can be easily and quickly grasped by visual recognition from the outside, so that a serious accident can be prevented.

Further, since the temperature inside the capacitor is directly measured, even if there is another heating element near the capacitor, the heat generation does not affect the maximum thermometer 2. Therefore, it is possible to more accurately determine whether or not the condenser is abnormal, in conjunction with visually checking the rise of the air bubbles in the hollow tube 3.

Further, since the maximum thermometer 2 and the hollow tube 3 can be continuously mounted on the case 1, it is possible to always check for occurrence of an abnormality. The highest thermometer 2 and the hollow tube 3 are provided with the tapered screws 4 of the mounting members 4 and 6.
Since the attachments 5 and 7 are fixed by screwing the attachments 5 and 7 into the a and the a, the attachment and detachment are easy, and the assembling and maintenance are not troublesome.

(4) Other Embodiments The present invention is not limited to the above embodiment,
The combination, quantity, material and the like of each member can be appropriately changed. For example, as one embodiment corresponding to the first aspect of the present invention, it is also possible to configure a capacitor having no hollow tube 3 and having only the maximum thermometer 2. As one embodiment corresponding to the second aspect of the present invention, it is also possible to configure a condenser having only the hollow tube 3 without the maximum thermometer 2.

The number of maximum thermometers 2 and the number of hollow tubes 3 of the present invention are not limited to one. For example, if a plurality of maximum thermometers 2 and hollow tubes 3 are inserted at equal intervals in the case 1, the temperature rise and insulation deterioration can be grasped in more detail, which can be used to identify abnormal points. .

The fixing structure and the fixing position of the maximum thermometer 2 and the hollow tube 3 are not limited to those in the above-described embodiment, but can be easily attached and detached and can secure the hermeticity of the case 1. If so, another configuration may be used. For example, it is also possible to insert the maximum thermometer 2 and the hollow tube 3 from the side of the case 1. At this time, the maximum thermometer 2 and the hollow tube 3
If the temperature sensing part 2b and the opening end 3b are inserted into the side surface of the case 1 so that the scale 2a and the closed end 3a are perpendicular to each other, the visual recognition becomes easy.

Further, materials such as capacitor paper, film, metal foil and the like used for the capacitor element housed in the case 1 can be appropriately changed according to required characteristics. The protection of the surface of the maximum thermometer 2 is not limited to silver plating or tin plating. The material of the hollow tube 3 is not limited to glass, and any material may be used as long as it has heat resistance to the temperature rise of the insulating oil and transparency so that bubbles can be visually recognized.

[0033]

A comparative test between one embodiment of the present invention and a conventional example using a thermo label will be described below.

(1) Configuration of Embodiment First, this embodiment has a rating of 440 VAC, three phases, and 50 Hz.
It is an SH capacitor of −540 μF, and the case size is 300 in width × 120 in depth × 390 in height (mm).
And as the highest thermometer, diameter 7φ, length 25cm,
A unit having a scale unit of 1 ° C. and a scale width of 20 ° C. to 100 ° C. was used. On the other hand, as a hollow tube, an outer diameter of 15φ and an inner diameter of 1
The one having a length of 0φ and a length of 15 cm was used.

(2) Configuration of Conventional Example Next, as a conventional example, a capacitor having the same rating as that of the above embodiment was used except that the maximum thermometer and the hollow tube were not provided. 5% on the top and top of the case
Thermolabels for 0 ° C., 60 ° C., and 70 ° C. are separately attached. The thermolabel for 50 ° C. is yellow at normal temperature and turns orange at 50 ° C. Thermo label for 60 ℃
It is yellow-red at normal temperature and turns red-purple at 60 ° C. A thermolabel for 70 ° C. is red at normal temperature and turns reddish purple at 70 ° C.

(3) Comparative heating test First, a comparative heating test between the embodiment and the conventional example will be described below.

Test Conditions The test conditions are as follows. That is, the capacitor of the embodiment and the capacitor of the conventional example are taken out after being put in a thermostat at the same temperature for 8 hours, and the indicated value of the maximum thermometer and the discoloration of the thermo label are visually observed and confirmed. The temperature condition of the thermostatic layer is 50 ° C. at the beginning, 60 ° C. at the next, and 70 ° C. at the end.

Test Results The test results under the above conditions are as follows. That is, when placed in a thermostat at 50 ° C., the highest thermometer of the example showed 51 ° C., and the thermolabel for 50 ° C. of the conventional example turned from yellow to orange. Next, in the 60 ° C. constant temperature bath, the highest thermometer of the example showed 62 ° C., and the thermolabel for 60 ° C. of the conventional example changed from yellow-red to reddish purple. further,
In a constant temperature bath at 70 ° C., the highest thermometer of the example indicated 72 ° C., and the thermolabel for 70 ° C. of the conventional example changed from red to reddish purple.

As described above, the temperature can be visually recognized in the embodiment and the conventional example. However, by diluting the ash and applying it to the thermo label by spraying, the dirt was simulated and adhered to the capacitor surface, and the same test as above was conducted.The discoloration of the thermo label could be clearly discriminated visually. could not.

(4) High Voltage Application Test Next, high voltage application tests of the embodiment and the conventional example will be described below.

Test Conditions The test conditions are as follows. That is, a voltage exceeding the healing voltage is applied to the embodiment and the conventional example,
Causes dielectric breakdown. At this time, the voltage is adjusted while confirming the healing with the generated sound, so that continuous healing is caused.

Test Results The test results under the above conditions are as follows. That is, when insulation breakdown occurs due to the application of a voltage, gas bubbles are generated due to gasification in both the embodiment and the conventional example, but in the conventional example, there is only a means for confirming the discoloration of the thermolabel due to the temperature rise. On the other hand, in the embodiment, bubbles rise in the hollow tube. Then, when the healing state is continued for a long time, bubbles accumulate in the hollow tube, so that the state of deterioration inside can be clearly recognized.

[0043]

As described above, according to the present invention,
With a simple configuration of inserting a maximum thermometer and hollow tube inside the case, it is possible to provide a power capacitor that can easily and quickly detect abnormalities inside the capacitor and prevent serious accidents before they occur. it can.

[Brief description of the drawings]

FIG. 1 is a front view of a capacitor showing an embodiment of a power capacitor of the present invention.

FIGS. 2A and 2B are a plan view and a cross-sectional view taken along line AA ', respectively, showing a mounting structure of a maximum thermometer on a case upper cover in the embodiment of FIG.

FIGS. 3A and 3B are a plan view and a cross-sectional view taken along the line BB ', respectively, showing the hollow tube in the embodiment of FIG.

FIGS. 4A and 4B are a plan view and a cross-sectional view taken along a line CC ', respectively, showing a mounting structure of a hollow tube of a case upper cover in the embodiment of FIG.
It is.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Case 1a ... Case top lid 1b ... Terminal 2 ... Maximum thermometer 2a ... Scale part 2b ... Temperature sensing part 3 ... Hollow tube 3a ... Closed part 3b ... Opening part 4,6 ... Mounting member 4a, 6a ... Taper screw 5, 7 ... Mounting tool

Claims (3)

[Claims] 1. A power capacitor in which a capacitor element formed by winding an overlapping dielectric layer and electrode layer is housed in a case filled with insulating oil, wherein the case is provided with a maximum thermometer. A power capacitor, wherein a scale portion of the highest thermometer is exposed to the outside of the case, and a temperature-sensitive portion of the highest thermometer is in insulating oil inside the case. 2. A power capacitor in which a capacitor element formed by winding an overlapping dielectric layer and electrode layer is housed in a case filled with insulating oil, has one end closed and the other end open. A hollow tube is provided in the case, a closed end side of the hollow tube is exposed to the outside of the case, an open end side of the hollow tube is inserted into the case, and insulating oil flows from the open end. A power capacitor, which is provided so as to be able to flow thereinto. 3. A power capacitor in which a capacitor element formed by winding an overlapping dielectric layer and electrode layer is housed in a case filled with insulating oil, wherein the case is provided with a maximum thermometer. The scale portion of the highest thermometer is exposed to the outside of the case, the temperature-sensitive portion of the highest thermometer is in the insulating oil inside the case, a hollow tube having one end closed and the other end open is provided. The closed end side of the hollow tube is provided in the case, and the closed end side of the hollow tube is exposed to the outside of the case. The open end side of the hollow tube is inserted into the case, and insulating oil is allowed to flow in from the open end. A power capacitor, characterized in that: