JP2973804B2 - Condenser voltage divider - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitor voltage divider for a voltage detector mounted on a gas-insulated electric device installed in a substation or the like and detecting a voltage applied to the device.

[0002]

2. Description of the Related Art As a voltage detecting means of a gas insulated electric device, an inner conductor is induced by an electrode mounted near an inner peripheral surface of a metal container housed in a central portion thereof while being electrically insulated from the metal container. A method using a so-called capacitor voltage divider that derives a voltage to the outside and outputs a secondary voltage proportional to the induced voltage is well known. FIG. 9 is a sectional view showing an example of a conventional capacitor voltage divider mounted on a gas-insulated electric device. In the figure, 1 is a metal container filled with an insulating gas therein, 2 is an inner conductor stored in the center of the metal container, and 3 is a main electrode mounted close to the inner peripheral surface of the metal container 1. is there. A mounting seat 1 a for mounting the main electrode 3 is fixed to a predetermined position on the inner peripheral surface of the metal container 1, and a mounting metal 3 a for mounting on the metal container 1 is provided on the outer periphery of the main electrode 3. Reference numeral 4 denotes an insulating ring for mounting the main electrode 3 while electrically insulating the main electrode 3 from the metal container 1. Reference numeral 6 denotes an insulating terminal for leading out a voltage induced in the main electrode 3 to the outside, and reference numeral 7 denotes a connection lead for electrically connecting the main electrode 3 and the insulating terminal 6. The main electrode 3 has a mounting bracket 3a and a mounting seat 1a fixed to the metal container 1.
The main electrode 3 and the insulating terminal 6 are connected to the connection lead 7 by attaching the insulating ring 4 to the metal container 1 with the mounting bolt 8.
And the induced voltage is led out.

In the capacitor voltage divider constructed in this manner, the main capacitance C ₁ between the inner conductor 2 and the main electrode 3 and the main electrode ground capacitance C ₂₁ between the main electrode 3 and the metal container 1. Are in series, and the voltage V ₀ applied between the inner conductor 2 and the metal container 1 is divided by the main capacitance C ₁ and the main electrode-to-ground capacitance C _21, and divided voltage V _t shown in the electrodes 3 in the formula 1 is induced.

(Equation 1) Normally, the divided voltage according to the formula 1 is too high for measurement or control, so that an external adjustment capacitor 10 and a main electrode-to-ground capacitance C _{21 are} used to adjust the voltage induced on the main electrode 3 to an appropriate voltage value. And connected in parallel to adjust to an appropriate voltage value. The capacitance C ₂ of the capacitance of the adjusting capacitor 10 and C ₂₂ partial pressure taps divided voltage V _t of the C ₂₁ + C ₂₂ next partial pressure taps will be as Formula 2.

(Equation 2) The equivalent circuit of the capacitor voltage divider constructed in this way is
It is as shown in 10.

[0004] The capacitor voltage divider constructed as described above has a small capacitance and does not take a secondary burden on the output side. Therefore, the detected voltage is converted into a digital signal or an optical signal and transmitted. A method of converting to a voltage value is adopted. The accuracy required for the detection voltage used for measurement or control in substations, etc. is usually required to be 1.0 class, and sometimes 0.5 class is required. In such a case,
The required accuracy of the capacitor voltage divider is required to be 0.2% or less in consideration of the accuracy of the signal conversion means.

[0005] The main electrode earth capacitance C ₂₁ and the main electrode between the main capacitance C ₁ and the main electrode 3 and the metallic container 1 between the capacitor voltage divider and the inner conductor 2 and the main electrode 3 as described above 3
Is the partial pressure tap capacitance C ₂ in the capacitance C ₂₂ of the adjustment capacitor 10 a divided voltage is adjusted to a proper value structure of divided voltage V _t is accurately grasp the main static capacitance C ₁ , determined by selecting the proper value of the capacitance C ₂₂ of the adjustment capacitor 10 for setting the partial pressure tap capacitance C _2. Connecting the adjustment capacitor 10 in parallel partial pressure tap capacitance C ₂ is large, the voltage detection precision of divider capacitive divider so that value can be grasped accurately depends on the accuracy of the main static capacitance. When the temperature of the internal conductor 2 and the main electrode 3 rises while the equipment is operating, each of them expands due to thermal expansion, the dimensions change, and the main capacitance C ₁ and the voltage dividing tap capacitance C ₂ change and are detected. It is necessary to consider that the voltage changes.

[0009] The main capacitance C ₁ of the capacitor voltage divider shown in FIG. 9 can be obtained by equation (3) for calculating the capacitance of the concentric cylindrical capacitor.

(Equation 3) ε ₀ : dielectric constant of the intervening insulator L: length of the main electrode D ₁ : diameter of the inner conductor D ₂ : inner diameter of the main electrode Equation 3 is an equation for obtaining the capacitance of an infinite-length cylindrical capacitor. In this case, since the electric field spreads at the end of the main electrode 3, the actual capacitance becomes smaller than the calculated main capacitance. End of the electric field of the spread relationship or around the metallic container 1 in the shape of the diameter D ₂ of diameter D ₁ and the main electrode 3 of the inner conductor 2 of the main electrode 3, for example, because the changes by such flexion portion is short, accurate It is difficult to grasp the appropriate capacitance.At the time of design, the capacitance is only a guide.At the time of manufacture, the voltage is actually applied and the detection voltage is measured to adjust the adjustment capacitor 10 to an appropriate value. The detection voltage is adjusted in such a manner.

[0007] The actual capacitor voltage divider, dimensional change of the inner conductor 2 and the main electrode 3 is primarily the capacitance C ₁ is changed caused by a temperature change in the portion that is mounted, the error of the detection voltage. In gas-insulated electrical equipment, the inner conductor 2
Is transmitted to the metal container 1 by the convection of the insulating gas filled in the surroundings, and is radiated from the surface of the metal container 1 to the outside air. Therefore, the temperature distribution of the gas insulated electric equipment is highest in the portion of the inner conductor 2, the temperature gradient of the filling insulating gas, the temperature gradient of the portion of the metal container 1 , the temperature gradient of the boundary transmitted from the outer surface to the outside air, and the like. Becomes The main electrode 3 of the capacitor voltage divider is mounted close to the inner surface of the metal container 2, and the temperature of the main electrode 3 is in the filled insulating gas, and since the insulating gas is convected, the central part The temperature difference between the inner conductor 2 and the inner wall of the metal container 1 is small.
Is estimated to be close to the temperature of the insulating gas. In actual gas-insulated electrical equipment, the temperature rise is estimated to be about 70 to 80% of the temperature rise value of the inner conductor 2, although there are differences depending on the rated voltage and the rated current.

The temperature distribution during operation of the capacitor voltage divider is as described above, and the capacitance C ₁ ■ during operation varies according to equation (4).

(Equation 4) α: linear expansion coefficient of the internal conductor material β: linear expansion coefficient of the main electrode material t ₁ : temperature rise value of the internal conductor t ₂ : temperature rise value of the main electrode D ₁ , D ₂ , ε ₀ , L Represents the same parts as at the time.

Now, assuming that the material of the inner conductor 2 and the material of the main electrode 3 are the same and α = β, equation (4) becomes equation (5).

(Equation 5) Since ln (1 + αt ₂ ) and ln (1 + αt ₁ ) in Expression 5 are sufficiently smaller than αt ₂ and αt ₁ , Expressions 6 and 7 are obtained.
Can be used to calculate an approximate value. _{ln (1 + αt 2) ≒} αt 2 ................................................... formula _{6 ln (1 + αt 1)} ≒ αt 1 ............................................. Expression 7 By substituting Expressions 6 and 7 into Expression 5, Expression 8 is obtained.

(Equation 6) Further, α (t ₂ −t ₁ ) in Expression 8 is ln (D ₂ / D ₁ )
Is sufficiently small with respect to the equation (9).

(Equation 7) By expanding Equation 9, the term of the square of α is sufficiently smaller than the other terms, and if it is set to 0, Equation 10 is obtained.

(Equation 8) The first term in Equation 9 is the same as Equation 3, and the second term is an increase in the main capacitance, which is related to the accuracy of the detection voltage.

[0010]

The conventional capacitor voltage divider is constructed as described above, and the electric field spreads at the end of the main electrode between the internal conductor and the main electrode, and the actual main electrostatic capacitance is increased. Is smaller than the value obtained by Equation 3, and its degree varies depending on the distance between the inner conductor and the main electrode. Therefore, it is difficult to grasp an accurate value of the main capacitance from the design time. In addition, a complicated adjustment operation of adjusting a detection voltage by applying a voltage after product assembly is required. In addition, there has been a problem that the main capacitance changes due to a rise in the temperature of the main body device on which the capacitor voltage divider is mounted, and the accuracy of the detection voltage deteriorates.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a capacitor voltage divider capable of grasping an accurate main capacitance from the time of design. It is another object of the present invention to provide a capacitor voltage divider in which a change in main capacitance is small even when a temperature rises and a desired voltage detection accuracy can be obtained in an operating temperature range.

[0012]

According to a first aspect of the present invention, there is provided a capacitor voltage divider having the same inner diameter as the main electrode at both ends of a main electrode mounted close to the inner wall of the metal container, and having one end connected to the main electrode. There is a flange connected to the electrode, and the other end has a configuration in which a pair of auxiliary electrodes formed in a shape extending toward the outer periphery with a predetermined radius of curvature to relax the electric field concentration are insulated and connected to the main electrode, and the auxiliary electrode Is electrically connected to the metal container.

According to a second aspect of the present invention, there is provided a capacitor voltage divider wherein one of a pair of auxiliary electrodes connected to both ends of a main electrode is directly fixed to an inner wall of a metal container and a metal fitting for mounting the main electrode. This is also used, and a metal fitting for mounting the main electrode is omitted.

According to a third aspect of the present invention, in the capacitor voltage divider, the main electrode is formed in a cylindrical shape and a slit is formed at one location on the circumference, and the inner diameter is the same as the inner diameter of the main electrode. One end has a stepped shape into which the main electrode is fitted, and the other end is fixed to the inner peripheral surface of the metal container at a predetermined interval with a pair of auxiliary electrodes extending toward the metal container wall facing each other, A cylindrical main electrode is mounted on the inner periphery of the auxiliary electrode while being electrically insulated.

According to a fourth aspect of the present invention, there is provided a capacitor voltage divider wherein the linear expansion coefficient of the inner conductor is smaller than a value obtained by dividing an allowable change rate of the main capacitance by a maximum temperature rise value of the inner conductor. The material of the main electrode is a material having a linear expansion coefficient close to a value obtained by dividing the product of the linear expansion coefficient of the internal conductor and the maximum temperature rise value by the maximum temperature rise value assumed for the main electrode.

In the capacitor voltage divider according to a fifth aspect of the present invention, the internal conductor material is made of copper, and the material of the main electrode is made of aluminum or an aluminum alloy containing aluminum as a main component.

According to a sixth aspect of the present invention, in the capacitor voltage divider, the electrode portion is provided with a main electrode at a predetermined position on the inner peripheral surface of the electrode body formed of a resin material, and a predetermined distance from an end of the main electrode. It is formed by attaching a conductive film serving as an auxiliary electrode to the outer peripheral surface from the placed position through the end portion.

[0018]

In the capacitor voltage divider according to the first aspect of the present invention, auxiliary electrodes having the same inner diameter as the main electrode are insulated and connected to both ends of the main electrode mounted close to the inner wall of the metal container. Accordingly, the electric field at the end of the main electrode does not spread, and the main capacitance between the main electrode and the internal conductor can be accurately grasped at the time of design.

In the capacitor voltage divider according to the second aspect of the present invention, one of a pair of auxiliary electrodes connected to both ends of the main electrode is directly fixed to the inner wall of the metal container to mount the main electrode. Therefore, the number of parts required for the production is small and the production cost can be reduced.

In the capacitor voltage divider according to a third aspect of the present invention, the main electrode has a cylindrical shape and has
Slits are provided in the axial direction, the pair of auxiliary electrodes are directly fixed to the metal container, and the main electrode is insulated and mounted between the pair of auxiliary electrodes, so the number of parts for mounting the main electrode is small. In addition to being easily mounted, the space for mounting the main electrode can be reduced.

[0021] In the capacitor voltage divider according to claim 4 of the present invention, the inner conductor determines an allowable change rate of the main capacitance between the inner conductor and the main electrode by a linear expansion coefficient of the inner conductor and a maximum temperature rise value. The material of the main electrode is the maximum temperature rise assumed for the main electrode by the product of the linear expansion coefficient of the internal conductor material and the maximum temperature rise value of the internal conductor. Since the coefficient of linear expansion is set to a value close to the value divided by the value, the main capacitance can be kept within the range of the allowable change rate even when the temperature rises.

In the capacitor voltage divider according to claim 5 of the present invention, the internal conductor material is made of copper and the material of the main electrode is formed of aluminum or an aluminum alloy containing aluminum as a main component. Even if there is, a capacitor voltage divider whose main capacitance is within an allowable range can be used.

In the capacitor voltage divider according to a sixth aspect of the present invention, the main electrode and the main electrode are provided at predetermined positions on the inner periphery of the electrode body in which the electrode portions of the main electrode and the auxiliary electrode are formed of a resin material in a predetermined shape. A conductive film to be an auxiliary electrode is formed by attaching the conductive film to the end of the inner peripheral surface from a position spaced from the extreme, so that the main capacitance can be accurately grasped from the beginning of design, and furthermore, the electrode part is mounted. Therefore, a capacitor voltage divider having a small number of components can be obtained.

[0024]

【Example】

Embodiment 1 FIG. Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1, 1, 2, 4, 6, and 7 have the same or the same functions as those of the conventional example shown in FIG. Reference numeral 13 denotes a main electrode, which is provided on its outer peripheral portion with a mounting metal 13a for mounting on the metal container 1, and on both ends thereof with flanges 13b to which the following auxiliary electrodes are connected. Reference numeral 15 denotes a pair of auxiliary electrodes connected to both ends of the main electrode 13, the inside diameter is the same as the inside diameter of the main electrode 13, one end is provided with a flange 15a for connecting to the main electrode 13, and the other. The end is formed in a shape spreading toward the outer periphery with a predetermined radius of curvature. Reference numeral 14 denotes an insulating ring for insulating the main electrode 13 and the auxiliary electrode 15 from each other. Reference numeral 17 denotes a connection lead for making the auxiliary electrode 15 the same potential as the metal container 1. The capacitor voltage divider is electrically insulated by inserting a pair of auxiliary electrodes 15 at both ends of the main electrode 13 with an insulating ring 14 interposed therebetween, and connected by bolts 18 to form an electrode portion, which is provided on the outer peripheral portion of the main electrode 13. Mounting metal
An insulating ring 4 is inserted between the mounting member 13a and the mounting seat 1a fixed to the inner peripheral surface of the metal container 1 so as to be electrically insulated, and the main electrode 13 and the insulating terminal 6 are connected by the connection lead 7. The pair of auxiliary electrodes 15 are connected to the metal container 1 by connection leads 17, respectively, and an adjustment capacitor (not shown) for adjusting a detection voltage value is connected between the insulating terminal 6 and the metal container 1. Is done.

In the capacitor voltage divider constructed as described above, the main capacitance C between the main electrode 13 and the internal conductor 2 is
_1, the main electrode 13 and the partial pressure tap capacitance C ₂ of the sum of the capacitance C ₂₂ of the adjusting capacitor capacitance C ₂₁ between the metallic container 1 becomes series, same as the conventional example It becomes an equivalent circuit shown in FIG. 10, the divided voltage V _t becomes a value shown in equation 2. The divided voltage V _t as usually suitable for signal conversion or measurement
Adjusted to 100V or 100 / √3V, auxiliary electrode
Reference numeral 15 is connected to the metal container 1 and the divided voltage V _t is connected to the main electrode 13.
Although there is a potential difference of (100 V or 100 / √3 V), the voltage of the inner conductor 2 is several tens to several hundreds of KV, which is sufficiently small, and the electric field distribution at the connection between the main electrode 13 and the auxiliary electrode 15 is ,
Not be affected by the divided voltage V _t, there is no spread of the electric field at the end portion of the main electrode 15, while main capacitance C ₁ between the inner conductor 2 and the main electrode 13 is originally designed by the equation 3 Can be accurately grasped.

Although the accuracy (error class) of the detection voltage required for the capacitor voltage divider depends on its use, it is usually 1.0 for voltage measurement or power transmission system control.
Class is required. When the error class is required to be 1.0 class as the voltage detection device, the capacitor voltage divider according to the present invention has a small capacitance and cannot take a secondary burden, so that only the voltage value is detected from the capacitor voltage divider. Then, the detected value is converted into a digital optical signal or the like and transmitted, and the received signal is inversely converted by a receiving side such as a control panel for measurement and control. In such a method, if the error class at the output end is required to be 1.0 class, errors of the signal converter, inverter, etc. are integrated, so that 0.1 to 0.2% is required for the capacitor voltage divider.
Degree is required.

In the case where strict accuracy is required for the detection voltage as described above, if the capacitor voltage divider is configured without using the auxiliary electrode as in the conventional example, the main capacitance becomes only a guide at the design stage. Since it is not possible to grasp, it is necessary to prepare many types of adjustment capacitors, actually apply a voltage after assembling the product, measure the capacitance, replace the adjustment capacitors with various values, and perform the adjustment for a long time. become Although this first embodiment, since the accessory auxiliary electrode 15 to the electrode portion, diverging portion of the electric field that inhibits the calculation accuracy of the capacitance C ₁ is not related to the main capacitance C ₁ auxiliary Electrode 15
Go to end, the main types of tuning capacitors electric field to prepare because it accurately grasped from the beginning designed becomes main capacitances C ₁ and approximately equal portions of the electrodes 13 is small, the adjustment of the detection voltage after assembly The effect that work becomes easy is acquired. Further, by using the auxiliary electrode 15, even when the capacitor voltage divider is mounted near the bent portion of the metal container, the electric field caused by the bending does not affect the portion of the main electrode 13, so that the metal container 1 is not affected. can secure install them primary capacitance C ₁ of accuracy even in the case of the bent portion.

Embodiment 2 FIG. Next, a second embodiment will be described with reference to FIG. This embodiment is basically the same as the first embodiment, except that one of the pair of auxiliary electrodes is
This is also a metal fitting for mounting the main electrode 13 to the metal container 1. 2, 1, 2, 6, 7, 13, 14, 15, and 17 have the same or the same functions as those of FIG. 9 showing the conventional example and FIG. 1 showing the first embodiment, and a description thereof will be omitted. Reference numeral 5 denotes an auxiliary electrode formed so that the inner diameter thereof is the same as that of the main electrode 13 and an open end of one end is widened toward the outer periphery with a predetermined radius of curvature, and the main electrode 13 is connected to a side opposite to the open end of the auxiliary electrode. The flange 5a is provided toward the outer periphery, and the outer periphery of the flange 5a is a fixed auxiliary electrode fixed to the metal container 1. The electrode portion is connected to the fixed auxiliary electrode 5 by electrically connecting one end of the main electrode 13 to the fixed auxiliary electrode 5 with an insulating ring 14 interposed therebetween and electrically insulating with a bolt 18. The main electrode 13 is electrically connected to the insulating terminal 6 by the connection lead 7, and the auxiliary electrode 15 is electrically insulated.
Are connected to the metal container 1 by connection leads 17.
A divided capacitor is connected to the insulating terminal 6 to adjust the divided voltage.

In the capacitor voltage divider configured as described above, one of the pair of auxiliary electrodes also serves as a metal fitting for mounting the main electrode 13, so that the number of components to be mounted is reduced, and the same effects as in the first embodiment are obtained. As a result, an effect that the assembling work of the electrode portion becomes easy can be obtained.

Embodiment 3 FIG. Further, a third embodiment will be described with reference to FIG. Reference numeral 23 in FIG. 3 denotes a main electrode which is formed in a cylindrical shape with a predetermined length, and has a notch in the axial direction at one location on the circumference, 25 denotes a pair of auxiliary electrodes, and an inner diameter which is the same as the main electrode 23. The open end of one end is formed to spread toward the inner peripheral surface of the metal container 1 with a predetermined radius of curvature, and the other end is formed in a stepped shape to which the main electrode 23 can be attached,
It is fixed to the metal container 1 with a predetermined interval so that the open end is on the outside. Reference numeral 24 denotes an insulating ring for electrically insulating the auxiliary electrode 25 from the main electrode 23. The outer shape of the main electrode 23 is reduced by overlapping the cuts as shown by a dashed line in FIG. 3, and an insulating ring 24 is inserted between the auxiliary electrode 25 and the pair of auxiliary electrodes 25 at the ends. The electrode portion is formed by inserting the cut portion into a predetermined diameter and mounting the cut portion with a predetermined diameter. The main electrode 23 and the insulating terminal 6 are electrically connected by the connection lead 7.

When the capacitor voltage divider is configured in this manner, the number of parts of the electrode portion is reduced, and in addition to the effect that the main capacitance can be accurately grasped from the design stage as in the first and second embodiments, The space for mounting the electrode 23 is reduced, the diameter of the metal container 1 can be reduced, and the assembling operation is simplified.

Embodiment 4 FIG. Next, a fourth embodiment will be described. The fourth embodiment corresponds to the fact that the main capacitance changes due to a rise in the temperature of the capacitor voltage divider during operation and the error in the detected voltage increases, and FIG. 1, FIG. 2 and FIG. Will be explained. Main electrode shown in FIGS. 1, 2 and 3
When the same material as the material of the inner conductor 2 is selected as the material of 13 or 23, if there is a temperature rise during operation, the main capacitance C ₁ increases as shown in the above-mentioned expression 10, and this main capacitance C _{1 1}
Increases, the error in the detection voltage increases.

When the inner conductor 2 and the main electrode 13 or 23 are made of the same material, the main capacitance C ₁ changes according to the above equation 5 due to a temperature rise. When the material of the internal conductor 2 and the material of the main electrode 13 or 23 are made of different materials, the change of the main capacitance C1 ₁ due to the temperature change is changed by the above-mentioned equation (4). When an approximate expression is derived in the same manner as when Expression 4 is arranged into Expression 9 and Expression 10, Expression 11 is obtained.

(Equation 9) The first term of the equation 11 is the same as the equation 3 for calculating the main capacitance C ₁ when there is no temperature rise, and the second term is the increase of the main capacitance due to the temperature rise.

If the amount of increase in the main capacitance when the temperature rises can be eliminated, the voltage detection accuracy can be improved. This can be achieved by setting the second term of equation 11 to zero. Equations 12 and 13 are obtained when the conditions are obtained.

(Equation 10)

[Equation 11] T ₂ / t ₁ is the value of about 0.7 to 0.8 in ordinary capacitor divider is the ratio of the temperature rise value of the main electrode 13 or 23 with respect to the temperature rise value of the internal conductor 2 in Formula 13.
Assuming that t ₂ / t ₁ = 0.7, the diameter ratio D ₂ / D _{1 of the} inner conductor 2 and the main electrode 13 or 23 where the main capacitance C ₁ does not change even if there is a temperature change, and the ratio of the respective linear expansion coefficients The relationship with β / α is a curve of S = 0 indicated by a dotted line shown in FIG. From this curve, the diameter ratio D between the inner conductor 2 and the main electrode 13 or 23 is obtained.
₂ / capacitors even when temperature changes due to the load current main capacitances C ₁ does not change by the ratio of D each linear expansion coefficient corresponding to ₁ beta / alpha selects each material so as to satisfy You can get a voltage divider.

However, since the actual temperature of the capacitor voltage divider changes depending on the operating conditions and the ambient temperature, the material of the inner conductor 2 and the material of the main electrode 13 or 23 that satisfies the condition of Expression 15 satisfies the linear expansion coefficient. Whatever you choose,
It is impossible to make the amount of change in the main capacitance C ₁ zero. Therefore, finding a condition for satisfying the temperature range which is operated amount of change main static capacitance C ₁ allowed for divider capacitive divider. The voltage detecting means constituted by using this kind of capacitor voltage divider has an allowable variation of the main capacitance of 0.1 as described above in consideration of an error of the divided voltage signal converting means.
About 1 to 0.2% is required. The amount of change in the main capacitance C ₁ of the capacitor voltage divider is the second term in Equation 11, and if the allowable change rate is S, the allowable change rate S is as shown in Equation 14.

(Equation 12) When the ratio of the linear expansion coefficients α and β of the material of the inner conductor 2 and the material of the main electrode 13 or 23 is obtained from Expression 14, Expression 15 is obtained.

(Equation 13) Equation 15 shows that by selecting α that satisfies the condition of S / αt ₁ = 1, the diameter ratio D ₂ / D ₁ between the inner conductor 2 and the main electrode 13 or 23 is selected.
Regardless, the material of the main electrode 13 or 23 can be selected.
The required linear expansion coefficient β of the material can be determined.

Further, to the allowable value or less by satisfying the conditions of the following formula 16 be smaller than the allowable change rate S of variation by the main electrostatic temperature increase of the capacitance C ₁ of the second term of equation 11 Can be.

[Equation 14] From Equation 16, the condition of the linear expansion coefficient β required for the material of the main electrode 13 or 23 is derived as shown in Equation 17.

(Equation 15) Therefore, the relationship between the allowable change amount S of the main capacitance C ₁ and the product αt ₁ of the linear expansion coefficient α of the internal conductor 2 and the maximum temperature rise value t ₁ is defined as an internal value satisfying the condition of S / αt ₁ > 1. By selecting the material of the conductor 2, it is not necessary to increase the linear expansion coefficient β of the main electrode 13 or 23 even if the diameter ratio D ₂ / D ₁ between the internal conductor 2 and the main electrode 13 or 23 increases. S / αt ₁ > 1
Select the material of the inner conductor 2 that satisfies the condition of
By selecting the material of the main electrode 13 or 23 so that the material of 13 or 23 satisfies the condition of the expression 17, regardless of the value of the diameter ratio D ₂ / D ₁ between the inner conductor 2 and the main electrode 13 or 23. allowable change amount S hereinafter become capacitor divider main capacitance C ₁ due to the temperature rise of the main capacitance C ₁ is obtained.

In the equation (14), t ₂ / t ₁ is a ratio of the temperature rise value of the main electrode 13 or 23 to the temperature rise value of the internal conductor 2.
The temperature distribution of the portion where the capacitor voltage divider of the gas insulated electric equipment is mounted is such that the heat generated by the load current in the inner conductor 2 is generated on the inner surface of the metal container 1 by the convection of the insulating gas filled in the metal container 1. It moves and transmits heat to the outside air from the surface of the metal container 1 by transmitting the wall of the metal container 1. The temperature of each part of the heat transfer system is highest at the part of the internal conductor 2, The temperature gradient is divided in proportion to the thermal resistance of the internal conductor 2. Even if the temperature of the internal conductor 2 changes, the thermal resistance of each section does not change. It is a value obtained by multiplying the divided ratio.

The main electrode 13 or 23 of the capacitor voltage divider is mounted in the filled insulating gas, the temperature of which is equal to the temperature of the filled insulating gas near the inner surface of the metal container 1. The diameter D ₁ of the inner conductor 2 of the capacitor voltage divider of this kind, even if small diameter required than the rated current, in order to average the internal electric field is intended to increase the diameter in accordance with the voltage class , the diameter ratio D ₂ / D ₁ of the main electrode 13 or 23 is not vary greatly with voltage class is set to a narrow range, the range of D ₂ / D ₁ is in the range of approximately 1.4 about 2.0. Therefore, it may be considered that the heat distribution is substantially similar, and that t ₂ / t ₁ is substantially constant regardless of the voltage class. In a temperature test of actual gas-insulated electrical equipment, the ratio of the temperature rise value of the inner conductor 2 to the surface temperature rise value of the metal container 1 is in the range of 0.6 to 0.7, although there is a slight difference due to the difference in the configuration. the temperature of the main electrodes 13 or 23 when inferred from thermal resistance ratio t ₂ / t ₁ = 0.
It is in the range of 7 to 0.8.

Although the temperature at the time of manufacturing the capacitor voltage divider varies depending on the season, it can be considered that it is almost in the range of 15 to 30 ° C. The capacitor voltage divider manufactured at the temperature in this range is compliant with the standard (JEC-181). ) Maximum ambient temperature specified in
Used at 40 ° C, then the maximum temperature of the inner conductor is 105
° C. and are defined, the temperature rise value t ₁ becomes 65 ° C.. The worst condition is when the capacitor divider is manufactured at a temperature of 15 ° C and the maximum temperature is 40 ° C, and the temperature of the inner conductor 2 at the maximum temperature of 40 ° C with respect to the temperature at the time of manufacture is 105 ° C.
The highest temperature rise and set, the main electrode 13 or 23 the ratio t ₂ / t ₁ of from 0.7 to 0.8 in terms of the temperature rise value of the temperature rise value and the inner conductor 2 of the difference between 90 ° C. of the inner conductor 2 and by selecting a material having a coefficient of linear expansion required in the internal conductors 2 and the main electrode 13 or 23 as a 0.7 worse, a temperature change during use, fall within the permissible range of the main capacitance C ₁ be able to.

The allowable change rate S of the main capacitance C ₁ required for the capacitor voltage divider is 0.1 to 0.2% as described above.
It is considered that the design target value is S = 0.0015 (0.15%). The setting conditions considered above are re-described as follows. S = 0.0015, t ₁ = 90 ° C., t ₂ / t ₁ = 0.7 Under these conditions, the condition that Expression 15 is not related to the diameter ratio D ₂ / D ₁ of the inner conductor 2 and the main electrode 13 or 23, S = α
The value of α that satisfies t ₁ is as follows. α = S / t ₁ = 0.0015 / 90 = 16.7 × 10 ^{-6 When} α is substituted into Equation 15, the ratio β / α of the coefficient of linear expansion between the inner conductor 2 and the main electrode 13 or 23 is 1.429. From this, β is calculated as 23.8 × 10 ⁻⁶ , and the coefficient of linear expansion of each of the inner conductor 2 and the main electrode 13 or 23 is α = 1.
By setting 6.7 × 10 ^-6 and β = 23.8 × 10 ^-6 , the allowable change rate of the main capacitance C ₁ regardless of the diameter under the above-mentioned temperature conditions t ₁ = 90 ° C. and t ₂ / t ₁ = 0.7. S = 0.0015 (0.
15%).

However, few materials are suitable for the linear expansion coefficients α and β of the inner conductor 2 and the main electrode 13 or 23 thus determined. selection and obtains the amount of change in the main capacitance C ₁ of the real product by the linear expansion coefficient of the selected material, can be applied in conditions amount change determined is within the allowable change rate S. As a material closest to α = 16.7 × 10 ⁻⁶ and β = 23.8 × 10 ⁻⁶ obtained above, a copper ｛linear expansion coefficient of 16.5 × 10 ⁻⁶ (at20
℃)｝, aluminum ｛linear expansion coefficient 23.8 × 10 ^-6 (at20
℃)｝. The material of the inner conductor 2 is copper, the main electrode 13 or
Aluminum or an aluminum alloy containing aluminum as a main component can be selected as the 23 materials. In this case, the ratio of the diameter of the inner conductor 2 to the diameter of the main electrode 13 or 23 is D ₂ / D _1.
The rate of change of the main static capacitance C ₁ corresponding to the temperature of the center conductor 2 is 90 ° C., 80 ° C., shown in FIG. 5 for the case of 70 ° C.. FIG.
At the maximum temperature of 90 ° C, the allowable change rate S is 0.00
15 (0.15%) or less, the rate of change decreases as the temperature decreases, and the main capacitance C ₁ can be within the allowable change rate S in the temperature range during operation.

Embodiment 5 FIG. Next, a fifth embodiment will be described. In the first to fourth embodiments, the case where the main electrode and the auxiliary electrode are formed of a metal material has been described. However, in the fifth embodiment, the main electrode and the auxiliary electrode are integrally formed by molding a resin material to form an electrode portion. 7 and 8 show the embodiment. In the figure, 30 is an electrode part,
A main electrode film 32 is provided at a predetermined position on an inner peripheral surface of an electrode body 31 formed by molding a resin material such as an epoxy casting resin into a predetermined shape, and a predetermined insulating interval 31a is separated from an end of the main electrode film 32. An auxiliary electrode film is formed on the outer peripheral surface from the
A conductive film is deposited to form 33. Main electrode film
32 and the auxiliary electrode film 33 can be easily formed by applying a conductive paint, spraying a metal, or vapor deposition. Main electrode film 32
Is connected to the insulation terminal 6 by the connection lead 7, and the divided voltage is led out. Auxiliary electrode 33 is connected directly to the metal container 1 through the connection leads 17.

When the electrode portion is configured in this manner, the main electrode film
The electric field distribution at the end of 32 becomes a substantially uniform electric field, the main capacitance can be grasped from the design time as in the first and second embodiments, and the number of parts for mounting the electrode part is reduced, Work becomes easy.

In this embodiment, the linear expansion coefficient of the electrode body 31 is determined by the diameter ratio D ₂ / D _{1, the} maximum temperature rise ratio t ₂ / t ₁ , and the main capacitance C of the inner conductor 2 and the main electrode film 32. _From the relationship with the allowable change rate S of ₁ , when a material adjusted to the linear expansion coefficient β required for the resin material of the main electrode body 32 using the above-mentioned formula 17 is used, the main capacitance C ₁ is reduced to the allowable change rate S. Within.

When a resin material having a large linear expansion coefficient β is used as described above, even if the allowable change rate S of the main capacitance C ₁ requires a small value, the main capacitance C ₁ is not affected even if the temperature rises. the capacitance C ₁ of accuracy can be obtained capacitor divider reserved. FIG. 6 shows the relationship between the coefficient of linear expansion β required for the main electrode 13 or 23 when the allowable change rate S = 0, S = 0.001, and S = 0.015 when the material of the inner conductor 2 is copper.
Shown in

[0046]

According to the capacitor voltage divider according to the first aspect of the present invention, the inner conductor is housed in the center of the metal container, and both ends are located near the inner periphery of the metal container of the gas insulated electric device filled with the insulating gas. A main electrode provided with an auxiliary electrode which is insulated and supported at the portion is attached, and the auxiliary electrode which is insulated and supported at both ends of the main electrode eliminates the spread of the electric field at the end of the main electrode. Since the main capacitance between the electrode and the internal conductor can be accurately grasped from the time of design, the number of types of adjustment capacitors required for adjusting the divided voltage after assembly is reduced, and adjustment work is simplified. In addition, since the influence of the surrounding electrodes on the main electrode portion is reduced, the degree of freedom of the mounting position of the capacitor voltage divider on the gas insulated electric device is increased.

In the capacitor voltage divider according to claim 2 of the present invention, one of the pair of auxiliary electrodes is fixed to the metal container as a mounting seat for mounting the electrode portion on the inner periphery of the metal container. Since the number of parts for mounting the capacitor voltage divider to the gas-insulated electrical equipment is reduced, the mounting operation can be easily performed, and the main capacitance can be accurately grasped from the design time as in the case of claim 1. The number of types of adjusting capacitors for adjusting the voltage and voltage is reduced, and the working time required for the adjusting operation is shortened.

In a capacitor voltage divider according to a third aspect of the present invention, the main electrode has a cylindrical shape, a slit is provided at one location on the circumference in the axial direction, and the pair of auxiliary electrodes are kept at a predetermined distance from the metal container. Since it is fixed and has a configuration in which an insulating ring is inserted between auxiliary electrodes and mounted, the main capacitance can be accurately grasped from the time of design as in claims 1 and 2, and the electrode portion is mounted. Since the space is reduced, the diameter of the metal container can be reduced, and the mounting operation can be simplified.

In the capacitor voltage divider according to claim 4 of the present invention, the inner conductor is made of a material having a linear expansion coefficient smaller than a value obtained by dividing an allowable change rate of the main capacitance by a maximum temperature rise value of the inner conductor. Since the electrode was made of a material having a coefficient of linear expansion larger than the product of the coefficient of linear expansion of the internal conductor material and the maximum temperature rise of the internal conductor divided by the maximum temperature rise of the main electrode,
A capacitor voltage divider in which the rate of change of the main capacitance does not exceed the allowable range in the operating temperature range regardless of the diameters of the inner conductor and the main electrode.

The capacitor voltage divider according to claim 5 of the present invention is configured such that the material of the internal conductor is copper and the material of the main electrode is aluminum or an aluminum alloy containing aluminum as a main component. With this configuration, it is possible to obtain a capacitor voltage divider in which the rate of change of the main capacitance is within 0.15% in the temperature range from the temperature at the time of manufacturing to the state where the maximum temperature is increased.

According to a sixth aspect of the present invention, in the capacitor voltage divider, the electrode portion is formed at a predetermined position on the inner peripheral surface of the electrode body formed of a resin material, and at a predetermined distance from an end portion of the main electrode. Since the conductive film to be the auxiliary electrode is attached to the outer peripheral surface beyond the end from the position where the is placed, the spread of the electric field at the end of the main electrode is eliminated, and the accurate main capacitance can be grasped from the design time Therefore, the number of types of adjusting capacitors for adjusting the partial pressure can be reduced, so that the adjusting capacitors can be easily adjusted, and the number of components to be mounted on the electrode portion is small, so that the assembling operation is simplified.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a capacitor voltage divider according to the present invention.
It is sectional drawing which shows Example of (a).

FIG. 2 shows a second embodiment of the capacitor voltage divider according to the present invention.
It is sectional drawing which shows Example of (a).

FIG. 3 shows a third embodiment of the capacitor voltage divider according to the present invention;
It is sectional drawing which shows Example of (a).

FIG. 4 is a view showing the necessity of a main electrode material corresponding to a diameter ratio of an inner conductor and a main electrode to obtain an allowable change rate of a main capacitance in a temperature change range during use of the capacitor voltage divider according to the present invention; It is a figure which shows the curve which calculates | requires a linear expansion coefficient.

FIG. 5 is a diagram showing a main voltage corresponding to the diameter ratio of the inner conductor and the main electrode when the internal conductor material of the capacitor voltage divider according to the present invention is copper and the main electrode material is aluminum or an aluminum alloy containing aluminum as a main component. It is a figure which shows the rate of change of capacitance for every operation temperature.

FIG. 6 is a diagram showing an allowable change rate of a main capacitance corresponding to a diameter ratio between an inner conductor and a main electrode when the inner conductor material of the capacitor voltage divider according to the present invention is copper;
FIG. 9 is a diagram showing a curve for determining a coefficient of linear expansion of a main electrode material to be 15;

FIG. 7 is a fifth embodiment of the capacitor voltage divider according to the present invention;
It is sectional drawing which shows Example of (a).

FIG. 8 is an enlarged cross-sectional view of an electrode end portion of FIG. 7;

FIG. 9 is a cross-sectional view showing a conventional capacitor voltage divider used in a gas-insulated electric device.

FIG. 10 is an equivalent circuit of a capacitor voltage divider.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal container 2 Inner conductor 6 Insulated terminal 13 Main electrode 14 Insulating ring 15 Auxiliary electrode 23 Main electrode 24 Insulating ring 25 Auxiliary electrode 30 Electrode part 31 Electrode body 32 Main electrode film 33 Auxiliary electrode film

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Naoto Yamamoto 8-1-1, Tsukaguchi-Honmachi, Amagasaki-shi Itami Works, Mitsubishi Electric Corporation (56) References JP 50-48419 (JP, A) JP 58-174856 (JP, A) JP-A-2-187667 (JP, A) JP-A-5-223853 (JP, A) JP-A-58-96265 (JP, U) (58) Fields investigated (Int) .Cl. ⁶ , DB name) G01R 15/06 H02G 5/06

Claims (6)

(57) [Claims] An inner conductor is housed in a central portion, and is provided concentrically with a predetermined length of the inner conductor provided inside a metal container filled with an insulating gas and insulated and supported by the metal container. A main electrode, an auxiliary electrode connected to an extension of the main electrode via an insulating member at both ends of the main electrode, and a terminal connected to the main electrode and led out of the metal container. An auxiliary electrode connected to both ends of the main electrode is electrically connected to the metal container. 2. The capacitor voltage divider according to claim 1, wherein one auxiliary electrode is fixed to the inner wall of the metal container, and the main electrode is fixed to the auxiliary electrode via an insulating member. 3. A pair of auxiliary electrodes fixed at predetermined intervals to an inner wall of a metal container filled with an insulating gas, the inner conductor being housed in a central portion thereof, and a cylindrically formed auxiliary electrode. An axial slit is provided at a location, a main electrode insulated and supported between the pair of auxiliary electrodes, and a terminal connected to the main electrode and led out of the metal container. And the capacitor voltage divider. 4. A predetermined length in which a central portion accommodates an internal conductor, is provided inside a metal container filled with an insulating gas, is insulated and supported by the metal container, and is arranged concentrically with the internal conductor. Main electrode and a terminal connected to the main electrode and led out to the outside, and the internal conductor divides an allowable change rate of the main capacitance between the internal conductor and the main electrode by a maximum temperature rise value of the internal conductor. The main electrode is made of a material having a coefficient of linear expansion smaller than the calculated value, and the main electrode has a coefficient of linear expansion larger than the value obtained by dividing the product of the coefficient of linear expansion of the internal conductor material and the maximum temperature rise of the internal conductor by the maximum temperature rise of the main electrode. A capacitor voltage divider characterized by comprising a material having: 5. A main electrode which is provided inside a metal container filled with an insulating gas and which is insulated and supported by the metal container and which is arranged concentrically with the internal conductor, wherein the main electrode is accommodated in a central portion thereof. A terminal connected to the main electrode and led out of the metal container, wherein the material of the internal conductor is copper, and the material of the main electrode is aluminum or an aluminum alloy containing aluminum as a main component. Capacitor voltage divider. 6. An inner conductor is accommodated in a central portion, is provided inside a metal container filled with an insulating gas, is supported concentrically with the inner conductor in the metal container, and has a main portion formed of a resin material and having a cylindrical shape. An electrode part which is molded and has a main electrode at the center of the inner peripheral surface and a conductive film to be an auxiliary electrode formed at an end of the inner peripheral surface, and an insulating terminal connected to the main electrode and led out of the metal container. Wherein the auxiliary electrode is electrically connected to a metal container.