JP2003021657A - Potential detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive potential detector having reduced fluctuation of a measuring potential caused by temperature conversion, concerning a potential-dividing type potential detector having an intermediate electrode provided between a conductor and a reference potential, for measuring the potential induced in the intermediate electrode, in order to measure the potential of the conductor. SOLUTION: This detector is equipped with a resistor having a characteristic capable of compensating the temperature change of a capacitance formed between the conductor 1 which is a potential measuring object and the intermediate electrode 5, placed between a structure 2 having reference potential to the intermediate electrode 5 and the conductor 1. The resistor may be constituted from an electrical network of the resistor formed by combining a resistor 8 having a prescribed temperature characteristic and resistors 9, 10 having a stable temperature characteristic, or constituted from a single resistor having a prescribed temperature characteristic A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a potential detector, and in particular, for the purpose of measuring the potential of a conductor, an intermediate electrode is provided between the conductor and a reference potential and the potential induced in this intermediate electrode is measured. The present invention relates to a pressure type electric potential detector.

[0002]

2. Description of the Related Art FIG. 7 shows a conventional voltage division type potential detector (hereinafter referred to as
It is a partial pressure type PD. 2] is a schematic configuration diagram showing the configuration of FIG. In the figure, 1 is a conductor, 2 is a structure, and 3 is a dielectric constant μ.
1 is a substance that forms an electrostatic capacitance C1, 4 is a substance having a dielectric constant of μ2, and forms an electrostatic capacitance C2.
Is an intermediate electrode.

FIG. 8 is a block diagram showing a conventional transformer for gas-insulated electrical equipment disclosed in, for example, Japanese Patent Laid-Open No. 8-75795. In FIG. 8, 101 is a grounded container, 101a
Is a flange formed on the end of the grounding container 101 so as to project outward, 102 is an insulating spacer attached between the flanges 101a at the connection part of the grounding container 101,
Reference numeral 03 designates a main circuit conductor supported by the insulating spacer 102, 104 designates a ground container housing the conductor 103, 10
Reference numeral 4a is a flange formed on the end of the ground container 104 so as to project outward.

Reference numeral 105 denotes a stepped portion having a predetermined diameter and depth formed on the flange portion 101a of the ground container 101, and has a plurality of screw holes formed therein. 106 is the ground container 101
In, the sealed terminal 107 is attached to the opening at a connection port formed at a predetermined distance from the flange 101a. Reference numeral 108 denotes a tubular member formed to have a predetermined diameter and length smaller than the inner diameter of the grounding container 101, and 109 denotes a first flange projecting outside one end of the tubular member 108, and the outer shape has a step. A plurality of mounting holes are formed by fitting with the portion 105 to form a mounting portion. The flanges 109 and 110 are parallel to each other, and the mounting surface of the first flange 109 and the screw hole of the second flange 110 are perpendicular to each other.

Reference numeral 111 denotes a cylindrical secondary electrode having an outer diameter substantially the same as that of the tubular member 108 and having a predetermined thickness and length, and 112 a center of the secondary electrode 111 in the thickness direction. A plurality of through holes formed in the portion, 113 is a pair of insulating members fitted to both ends of the through hole 112, and has an outer diameter substantially the same as the thickness of the secondary electrode 111 and a predetermined center portion. A bolt hole having a diameter is formed. 114 is an end electrode arranged at the other end of the secondary electrode 111, 115 is an end electrode 114,
It is a tightening screw that penetrates the insulating member 113, the secondary electrode 111, and the insulating member 113 and is fastened to the second flange 110.

The cylindrical member 108 having the end electrode 114 and the secondary electrode 111 attached to the other end in this manner is positioned by fitting one end into the step portion 105 of the grounding container 101, and then mounting screw. It is fixed to the ground container 101 by 116. Then, the secondary electrode 111 is connected to the signal converter 117 arranged at the connection port 106 by the lead wire 118. In this way, the capacitor type voltage divider unit is formed.

[0007]

In the case of the conventional partial pressure type PD which is one example of the potential detector, the substance 3 having a dielectric constant μ1 is used.
Was an insulator having a specific dielectric constant such as SF6 gas. Therefore, the dielectric constant μ of the substance 3 having the dielectric constant μ1
There is a problem that the temperature characteristic of 1 affects the output of the potential detector.

Further, there is a problem that the output of the potential detector is affected by the temperature change of the dielectric constant of the insulator filled in the space between the intermediate electrode 5 and the structure 2.

In addition, there is a problem that the output of the potential detector fluctuates because the mutual positional relationship changes due to the temperature change of the conductor 1, the intermediate electrode 5, and the structure 2.

The present invention has been made to solve the above problems, and an object thereof is to obtain a potential detector capable of suppressing the influence of temperature change.

[0011]

The present invention provides a conductor whose potential is to be measured, a structure having a reference potential with respect to the conductor, and a structure which is provided between the structure and the conductor and which is applied to the conductor. An intermediate electrode that divides the generated AC voltage; a substance that is provided between the conductor and the intermediate electrode, has a predetermined dielectric constant μ1, and forms a predetermined capacitance C1;
The potential detector is provided between the structure and the intermediate electrode, and includes a resistance unit having a specific temperature characteristic A for compensating the temperature change of the capacitance C1.

Further, an integrator for integrating the voltage across the resistance means is further provided.

Further, the resistance means has a predetermined temperature characteristic B.
And a resistance network in which a plurality of resistors having stable temperature characteristics are combined, and the temperature characteristics of the entire resistance network are equivalent to the temperature characteristics A.

The resistor having the specific temperature characteristic B is made of platinum.

The resistor having the specific temperature characteristic B is made of copper.

The dielectric constant μ is filled between the structure and the intermediate electrode and forms a parallel circuit with the resistance means.
It further comprises two substances.

Further, capacitors are further provided at both ends of the resistance means.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 shows a potential detector according to a first embodiment of the present invention, in which 1 is a conductor, 2 is a structure having a reference voltage with respect to conductor 1, and 3 is an insulator having a dielectric constant μ1. A material supporting the conductor 1, 5 is provided at the end of the material 3 opposite to the conductor 1, and is an intermediate electrode for dividing the AC voltage applied to the conductor 1, and 6 is an intermediate electrode 5. A resistor provided between the structure 2 and the predetermined temperature characteristic A is shown.

Next, the operation of the potential detector shown in FIG. 1 will be described. In FIG. 1, an AC voltage having the structure 2 as a reference potential is applied to the conductor 1. The AC voltage applied to the conductor 1 is divided by the intermediate electrode 5. The voltage division ratio at this time is determined by the ratio of the impedance Z1 determined by the shape of the conductor 1 and the shape of the intermediate electrode 5 and the dielectric constant of the substance 3 having the dielectric constant μ1 to the resistance value of the resistor 6 having the temperature characteristic A. To be done. As is well known, the impedance Z1 is calculated from the effective electrode area S formed by the conductor 1 and the intermediate electrode 5, the effective distance d between the conductor 1 and the intermediate electrode 5, and the dielectric constant μ1 of the substance 3 having the dielectric constant μ1. Calculated capacitance C =
Impedance Z1 is obtained from μ1 × S ÷ d, where Z1 = d ÷ when the alternating voltage applied to the conductor 1 is Vi, the frequency of the alternating voltage Vi is f, and the complex display is j.
(J × 2 × π × f × μ1 × S). The voltage Vo generated at the intermediate electrode 5 is the AC voltage applied to the conductor 1
i, the frequency of the AC voltage Vi is f, and the resistance value of the resistor 6 having the temperature characteristic A is R, Vo = Vi × R ÷ (Z
1 + R) = Vi × R ÷ ((d ÷ (j × 2 × π × f × μ1
× S)) + R).

When using R << Z1, Vo = Vi × R ÷
Z1 = j × 2 × π × f × R × μ1 × S × Vi ÷ d.

When the temperature of the potential detector in the present invention changes, the dielectric constant μ1 of the substance 3 having the dielectric constant μ1 changes, and the relative positional relationship between the conductor 1, the intermediate electrode 5, and the structure 2 also changes, The effective electrode area S formed by the conductor 1 and the intermediate electrode 5 and the effective distance d between the conductor 1 and the intermediate electrode 5 change. Therefore, the capacitance formed by the conductor 1, the intermediate electrode 5, and the substance 3 having a dielectric constant μ1 that fills the space between them changes, and the impedance Z1 changes. The resistor 6 in the present embodiment has a temperature characteristic A showing a change equivalent to the temperature change of the impedance Z1 due to the change of μ1, S, d at this time. By selecting such a resistor 6, in the present embodiment, a change in the output voltage Vo of the potential detector due to the temperature can be suppressed and a stable output can be obtained.

As described above, in the present embodiment,
The dielectric constant μ1 of the substance 3, the effective electrode area S formed by the conductor 1 and the intermediate electrode 5, and the temperature change of the impedance Z1 due to the change of the effective distance d between the conductor 1 and the intermediate electrode 5 are equivalent to The resistor 6 having the temperature characteristic A indicating the change is
By introducing between the intermediate electrode and the structure, it is possible to suppress the change of the output voltage Vo of the potential detector due to the temperature, and it is possible to obtain the potential detector that can obtain a stable output with respect to the temperature.

Embodiment 2. FIG. 2 shows a potential detector according to a second embodiment of the present invention.
Is a conductor, 2 is a structure, 3 is a substance having a dielectric constant of μ1, 5 is an intermediate electrode, 6 is a resistor having a temperature characteristic A, and 7 is an integrator for integrating the voltage Vr across the resistor 6.

Next, the operation will be described. The voltage Vr across the resistor 6 having the temperature characteristic A is the same as in the first embodiment.
Of the output voltage Vo of Vr = j × 2 × π × f × R ×
Since μ1 × S × Vi ÷ d, the waveform is a waveform obtained by differentiating the AC voltage Vi applied to the conductor 1. In order to obtain a voltage waveform proportional to the AC voltage Vi as the output of the potential detector, the voltage Vr across the resistor 6 having the temperature characteristic A is integrated by the integrator 7 to be proportional to the AC voltage Vi. The output voltage Vo can be obtained.

As described above, in the present embodiment,
In addition to the configuration of the first embodiment described above, an integrator 7 for integrating the voltage Vr across the resistor 6 having the temperature characteristic A is further added.
Is provided and the output voltage Vo proportional to the AC voltage Vi applied to the conductor 1 is obtained by integrating the voltage Vr.
It is possible to obtain a potential detector that can obtain a stable output with respect to temperature.

Embodiment 3. 3 shows a potential detector according to a third embodiment of the present invention. In FIG.
Is a conductor, 2 is a structure, 3 is a substance having a dielectric constant of μ1, 5 is an intermediate electrode, 8 is a resistor having a temperature characteristic B, and 9 and 10 are resistors having a predetermined resistance value and having a stable temperature characteristic. .

Next, the operation will be described. The combined resistance of the resistor network including the resistor 8, the resistor 9, and the resistor 10 having the temperature characteristic B is the same as that in the first embodiment.
This is intended to compensate for the change due to temperature in the electrostatic capacitance formed by the substance 3 having a dielectric constant μ1 sandwiched between the two. In the third embodiment shown in FIG. 3, for example, even when a resistor having a fixed temperature characteristic such as platinum is used as the material of the resistor 8 having the temperature characteristic B, the resistor 9 and the resistor 10 are used. By appropriately selecting the value of the resistance value of, the combined resistance value and the temperature coefficient can be arbitrarily set within the range of the temperature coefficient of platinum. The voltage between the conductor 1 and the structure 2 is Vi, the impedance of the capacitance formed by the substance 3 having a dielectric constant μ1 between the conductor 1 and the intermediate electrode 5 is Z1, and the resistance value of the resistor 8 having the temperature characteristic B. Is R8, the resistance value of the resistor 9 is R9, and the resistance value of the resistor 10 is R10, Z1 = d ÷ (j × 2 ×
π × f × μ1 × S), and the combined resistance of the resistor 8, resistor 9, and resistor 10 having the temperature characteristic B is Rg, Rg = R1
0 × (R8 + R9) ÷ (R8 + R9 + R10), where Vm is the potential of the intermediate electrode 5, Vm = Rg ÷ (Z1 + R
g) × Vi, where Vo = Vm × R9 ÷ (R
8 + R9) = Rg × R9 ÷ ((R8 + R9) × (Z1 +
If Rg)) × Vi and Rg << Z1, then Vo = Vi × R
g × R9 ÷ ((R8 + R9) × (Z1)) = Vi × R1
0 × (R8 + R9) ÷ (R8 + R9 + R10) × R9 ÷
((R8 + R9) × (Z1)) = Vi × R10 × R9 ÷
(R8 + R9 + R10) ÷ (Z1). Therefore, the dielectric constant μ1 between the conductor 1 and the intermediate electrode 5 is increased due to the temperature rise.
When the impedance Z1 decreases due to the increase in the capacitance of the substance 3, the resistance value R8 of the resistor 8 having the temperature characteristic B increases with temperature, and thus the change in the output voltage is reduced.

On the other hand, although the example of FIG. 3 corresponds to a negative temperature coefficient, it is also possible to correspond to a positive temperature coefficient by exchanging the positions of the resistors 8 and 9 having the temperature characteristic B. . The output voltage in this case is Vo = Vi × R10 × R8
÷ (R8 + R9 + R10) ÷ (Z1) When the impedance Z1 increases due to the decrease in the capacitance of the substance 3 having a dielectric constant μ1 between the conductor 1 and the intermediate electrode 5 due to the temperature increase, the value of R8 of the molecule also increases, and the increase in impedance Z1 is Since it is canceled, a potential detector with reduced influence of temperature can be realized.

As described above, in the present embodiment,
Instead of the resistor having the specific temperature characteristic A shown in the first and second embodiments described above, the resistor 8 having a predetermined temperature characteristic B and the temperature characteristic are stable in order to have an arbitrary temperature characteristic. Since the resistor circuit network in which a plurality of resistors are combined is provided, it is possible to obtain the potential detector that can suppress the influence of the temperature change and obtain a stable output with respect to the temperature.

Fourth Embodiment 4 shows a potential detector according to a fourth embodiment of the present invention. In FIG.
Is a conductor, 2 is a structure, 3 is a substance having a dielectric constant of μ1, 5 is an intermediate electrode, 8 is a resistor having a temperature characteristic B, 9 and 10 have a predetermined resistance value, and the temperature characteristic is stable. Indicates a resistor. In the example of the third embodiment shown in FIG. 3, although the case where the resistor 8 having the temperature characteristic B is made of platinum is described, copper is adopted as the resistor 8 having the temperature characteristic B. You may. The temperature coefficient of resistance of copper is about 0.4% / ° C. in the normal temperature range, and although the temperature characteristic similar to that of platinum can be obtained, the unit price is low, so that an inexpensive potential detector can be realized.

Embodiment 5. FIG. 5 shows a potential detector according to a fifth embodiment of the present invention, which comprises a resistor 8, a resistor 9, and a resistor 10 having the temperature characteristic B shown in the third and fourth embodiments. Dielectric constant μ2 in parallel with resistor network
The substance 4 is filled between the intermediate electrode 5 and the structure 2 to form a capacitor. With the capacitor, a surge that is superimposed on the output of the potential detector can be suppressed, and a potential detector that is less susceptible to the surge can be realized. In addition, since the substance 4 having a dielectric constant μ2 also has a function of supporting the support of the intermediate electrode 5, for example, a support insulator, there is an advantage that an inexpensive potential detector can be realized.

Sixth Embodiment FIG. 6 shows a potential detector according to a sixth embodiment of the present invention, which comprises a resistor 8, a resistor 9, and a resistor 10 having the temperature characteristic B shown in the third and fourth embodiments. A surge absorbing capacitor 11 is attached in parallel with the resistor network. The capacitor 11 is an external capacitor, and the intermediate electrode 5
The external surge induced between the structure and the structure 2 is suppressed. Since the surge is suppressed by the capacitor 11, each of the resistance elements having the temperature characteristic B, that is, the resistance element 8, the resistance element 9, and the resistance element 10 having low working voltage and withstand voltage can be selected. It has the feature of realizing a potential detector.

[0033]

The present invention provides a conductor whose potential is to be measured, a structure having a reference potential with respect to the conductor, and an AC voltage applied to the conductor, which is provided between the structure and the conductor. Is provided between the conductor and the intermediate electrode, and has a predetermined dielectric constant μ1.
A substance that forms a predetermined capacitance C1 and a resistance means that is provided between the structure and the intermediate electrode and has a specific temperature characteristic A that compensates for a temperature change of the capacitance C1 are provided. Since it is a potential detector, it is possible to suppress the influence of temperature change and obtain a stable output with respect to temperature.

Further, since the integrator for integrating the voltage across the resistance means is further provided, an output voltage proportional to the voltage applied to the conductor can be obtained, so that the influence of temperature change can be suppressed. It is possible to obtain a stable output with respect to temperature.

The resistance means has a predetermined temperature characteristic B.
Of the resistors constituting the resistor network, since the resistor network having a plurality of resistors having stable temperature characteristics is combined, and the temperature characteristic of the entire resistor network is equivalent to the temperature characteristic A. By devising a combination, it is possible to easily have an arbitrary temperature characteristic.

Further, since the resistor having the specific temperature characteristic B is made of platinum, it is possible to reliably compensate the temperature change.

Since the resistor having the specific temperature characteristic B is made of copper, an inexpensive potential detector can be obtained.

A dielectric constant μ which is filled between the structure and the intermediate electrode and constitutes a parallel circuit with the resistance means.
Since the substance of No. 2 is further provided, it is possible to obtain a potential detector that suppresses a surge that is superimposed on the output of the potential detector and is not easily affected by the surge.

Further, since capacitors are further provided at both ends of the resistance means, an external surge induced between the intermediate electrode and the structure can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a potential detector according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a potential detector according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a potential detector according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a potential detector according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a potential detector according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of a potential detector according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional partial pressure type PD.

FIG. 8 is a block diagram of a conventional transformer for gas insulated electrical equipment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 conductor, 2 structure, 3 substance of permittivity μ1, 4 substance of permittivity μ2, 5 intermediate electrode, 6 resistor of temperature characteristic A, 7 integrator, 8 resistor of temperature characteristic B, 9 resistor,
10 resistor, 11 capacitor, 101 grounding container,
101a flange, 102 insulating spacer, 103
Main circuit conductor, 104 grounding container, 104a flange,
105 step, 106 connection port, 107 sealed terminal,
108 tubular member, 109 flange, 110 flange, 111 secondary electrode, 112 through hole, 113 insulating member, 114 end electrode, 115 tightening screw, 116 mounting screw, 117 signal converter, 118 lead wire.

Claims (7)

[Claims] 1. A conductor whose potential is to be measured, a structure having a reference potential with respect to the conductor, and an intermediate that is provided between the structure and the conductor and divides an AC voltage applied to the conductor. An electrode, a substance provided between the conductor and the intermediate electrode, having a predetermined dielectric constant μ1 and forming a predetermined capacitance C1, and provided between the structure and the intermediate electrode. And a resistance means having a predetermined temperature characteristic A for compensating the temperature change of the capacitance C1. 2. The potential detector according to claim 1, further comprising an integrator for integrating the voltage across the resistance means. 3. The resistance means is composed of a resistor network in which a resistor having a predetermined temperature characteristic B and a plurality of resistors having stable temperature characteristics are combined, and the temperature characteristic of the entire resistor network is the temperature characteristic. It is equivalent to A, The potential detector of Claim 1 or 2 characterized by the above-mentioned. 4. The potential detector according to claim 1, wherein the resistor having the specific temperature characteristic B is made of platinum. 5. The potential detector according to claim 1, wherein the resistor having the specific temperature characteristic B is made of copper. 6. The method according to claim 1, further comprising a substance having a dielectric constant of μ2, which is filled between the structure and the intermediate electrode and forms a parallel circuit with the resistance means.
The potential detector according to any one of 1. 7. The potential detector according to claim 1, further comprising capacitors provided at both ends of the resistance means.