CA2678212A1 - Optical voltage measuring apparatus - Google Patents
Optical voltage measuring apparatus Download PDFInfo
- Publication number
- CA2678212A1 CA2678212A1 CA 2678212 CA2678212A CA2678212A1 CA 2678212 A1 CA2678212 A1 CA 2678212A1 CA 2678212 CA2678212 CA 2678212 CA 2678212 A CA2678212 A CA 2678212A CA 2678212 A1 CA2678212 A1 CA 2678212A1
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- Canada
- Prior art keywords
- electrostatic capacitance
- voltage
- main circuit
- buried
- buried electrode
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/241—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using electro-optical modulators, e.g. electro-absorption
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B13/00—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle
- H02B13/02—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle with metal casing
- H02B13/035—Gas-insulated switchgear
- H02B13/0356—Mounting of monitoring devices, e.g. current transformers
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measurement Of Current Or Voltage (AREA)
- Gas-Insulated Switchgears (AREA)
- Installation Of Bus-Bars (AREA)
Abstract
There is provided an optical voltage measuring apparatus including a main circuit conductor, a dielectric body which insulatingly supports the main circuit conductor and is fixed to a grounding member, a buried electrode buried in the dielectric body, and an electro-optic element which is connected to the buried electrode and measures a voltage of the main circuit conductor, wherein a voltage, which is divided by an electrostatic capacitance ratio between an electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and an electrostatic capacitance, which is created between the buried electrode and the grounding member, is applied to the electro-optic element.
Description
i TITLE OF THE INVENTION
OPTICAL VOLTAGE MEASURING APPARATUS
BACKGROUND OF THE INVENTION
The present invention relates to an optical voltage measuring apparatus which can improve the measurement precision of a main circuit voltage of a switching device which is used, for example, in a generating/transforming station.
In a high-voltage switching device of several kV
or more, a main circuit voltage is measured by electrostatic capacitance voltage division or resistance voltage division. In this kind of ineasuring deice, there is known a cone-shaped insulation spacer which is used in a gas-insulation switching device as shown in FIG. 1(see, e.g. Jpn. Pat. Appln. KOKAI
Publication No. 2000-232719 (page 4, FIG. 1).
As shown in FIG. l, a main circuit conductor 1 is supported by a cone-shaped insulation spacer 2, and is insulated from a cylindrical tank 3 which is at a ground potential. The insulation spacer 2 is made up of a first dielectric body 4 which is formed by injecting an epoxy resin, and a second dielectric body 5 which has a lower resistivity than the first dielectric body 4 and is formed in a layer shape on the surface of the first dielectric body 4. An annular buried electrode 6 is buried in the first dielectric body 4 on the tank 3 side. An annular buried metal 7 is provided at both ends of an outer peripheral end portion, and is airtightly fixed to the end of the tank 3.
A secondary-side capacitor 8 is connected to the buried electrode 6, and the buried electrode 6 is grounded via the buried metal 7. A detection impedance 9 is connected in parallel with the secondary-side capacitor 8. A primary-side electrostatic capacitance and a primary-side volume resistance 11 by the 10 second dielectric body 5 are formed between the main circuit conductor 1 and the buried electrode 6.
Thereby, a voltage, which is divided by the primary-side electrostatic capacitance 10 and the secondary-side capacitor 8 including the detection impedance 9, can be measured. The second dielectric body 5 is provided in order to improve the time constant. In the case of high frequencies, voltage division is executed by the primary-side volume resistance 11, and the main circuit voltage can precisely be measured.
On the other hand, there is known a voltage measurement technique using an electro-optic element (Pockels effect element) (see, e.g. Jpn. Pat. Appln.
KOKAI Publication No. 2000-258465 (page 3, FIG. 1)).
However, the voltage that can be applied to the electro-optic element is about 1 kV or less, and a voltage divider has to be used in order to measure a high voltage. Thus, a voltage divider with high precision is required and, if dielectric strength, etc.
is considered, the size of the voltage divider becomes large, and the gas-insulation switching device itself becomes large in size.
In the main circuit voltage measurement of the above-described conventional high-voltage switching device, there are the following problems. If an electro-optic element is to be used, a dedicated voltage divider is required, and the size of the gas-insulation switching device becomes large. Then, a voltage dividing circuit may be fabricated by using the insulation spacer 2 to measure the main circuit voltage. In this case, the primary-side electrostatic capacitance 10 and primary-side volume resistance 11 of the primary-side voltage dividing circuit are present within the tank 3, and the secondary-side capacitor 8 and detection impedance 9 of the secondary-side voltage-dividing circuit are present in the air outside the tank 3. A temperature rise occurs due to power-on current within the tank 3, and a temperature variation occurs outside the tank 3. It is difficult to make similar the temperature characteristics of the primary-side and secondary-side voltage dividing circuits. In addition, although the humidity in the tank 3 is low, there is an effect of humidity on the outside of the tank 3.
OPTICAL VOLTAGE MEASURING APPARATUS
BACKGROUND OF THE INVENTION
The present invention relates to an optical voltage measuring apparatus which can improve the measurement precision of a main circuit voltage of a switching device which is used, for example, in a generating/transforming station.
In a high-voltage switching device of several kV
or more, a main circuit voltage is measured by electrostatic capacitance voltage division or resistance voltage division. In this kind of ineasuring deice, there is known a cone-shaped insulation spacer which is used in a gas-insulation switching device as shown in FIG. 1(see, e.g. Jpn. Pat. Appln. KOKAI
Publication No. 2000-232719 (page 4, FIG. 1).
As shown in FIG. l, a main circuit conductor 1 is supported by a cone-shaped insulation spacer 2, and is insulated from a cylindrical tank 3 which is at a ground potential. The insulation spacer 2 is made up of a first dielectric body 4 which is formed by injecting an epoxy resin, and a second dielectric body 5 which has a lower resistivity than the first dielectric body 4 and is formed in a layer shape on the surface of the first dielectric body 4. An annular buried electrode 6 is buried in the first dielectric body 4 on the tank 3 side. An annular buried metal 7 is provided at both ends of an outer peripheral end portion, and is airtightly fixed to the end of the tank 3.
A secondary-side capacitor 8 is connected to the buried electrode 6, and the buried electrode 6 is grounded via the buried metal 7. A detection impedance 9 is connected in parallel with the secondary-side capacitor 8. A primary-side electrostatic capacitance and a primary-side volume resistance 11 by the 10 second dielectric body 5 are formed between the main circuit conductor 1 and the buried electrode 6.
Thereby, a voltage, which is divided by the primary-side electrostatic capacitance 10 and the secondary-side capacitor 8 including the detection impedance 9, can be measured. The second dielectric body 5 is provided in order to improve the time constant. In the case of high frequencies, voltage division is executed by the primary-side volume resistance 11, and the main circuit voltage can precisely be measured.
On the other hand, there is known a voltage measurement technique using an electro-optic element (Pockels effect element) (see, e.g. Jpn. Pat. Appln.
KOKAI Publication No. 2000-258465 (page 3, FIG. 1)).
However, the voltage that can be applied to the electro-optic element is about 1 kV or less, and a voltage divider has to be used in order to measure a high voltage. Thus, a voltage divider with high precision is required and, if dielectric strength, etc.
is considered, the size of the voltage divider becomes large, and the gas-insulation switching device itself becomes large in size.
In the main circuit voltage measurement of the above-described conventional high-voltage switching device, there are the following problems. If an electro-optic element is to be used, a dedicated voltage divider is required, and the size of the gas-insulation switching device becomes large. Then, a voltage dividing circuit may be fabricated by using the insulation spacer 2 to measure the main circuit voltage. In this case, the primary-side electrostatic capacitance 10 and primary-side volume resistance 11 of the primary-side voltage dividing circuit are present within the tank 3, and the secondary-side capacitor 8 and detection impedance 9 of the secondary-side voltage-dividing circuit are present in the air outside the tank 3. A temperature rise occurs due to power-on current within the tank 3, and a temperature variation occurs outside the tank 3. It is difficult to make similar the temperature characteristics of the primary-side and secondary-side voltage dividing circuits. In addition, although the humidity in the tank 3 is low, there is an effect of humidity on the outside of the tank 3.
Under the circumstances, there is a demand for a measuring apparatus which can measure a main circuit voltage with high precision, with the fabrication of a voltage dividing circuit which can make similar environmental characteristics such as temperature and humidity by using, e.g. the insulation spacer 2 that is an insulating structure of a gas-insulation switching apparatus. In addition, there is a demand for a measuring apparatus which can prevent, in the case of using an electro-optic element, a large variation in secondary-side impedance due to the connection of the electro-optic element, and which can obtain a stable voltage division ratio.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical voltage measuring apparatus which measures a main circuit voltage with high precision, without being affected by environmental characteristics.
According to an aspect of the present invention, there is provided an optical voltage measuring apparatus comprising: a main circuit conductor, a dielectric body which insulatingly supports the main circuit conductor and is fixed to a grounding member, a buried electrode buried in the dielectric body, and an electro-optic element which is connected to the buried electrode and measures a voltage of the main circuit ------------conductor, wherein a voltage, which is divided by an electrostatic capacitance ratio between an electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and an electrostatic capacitance, which is created between the buried electrode and the grounding member, is applied to the electro-optic element.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
FIG. 1 is a cross-sectional view of an insulation spacer which functions as a conventional voltage divider;
FIG. 2 is a cross-sectional view of an insulation spacer which functions as a voltage divider according to Embodiment 1 of the present invention; and FIG. 3 is a cross-sectional view of a post spacer which functions as a voltage divider according to Embodiment 2 of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will now be described with reference to the accompanying drawings.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide an optical voltage measuring apparatus which measures a main circuit voltage with high precision, without being affected by environmental characteristics.
According to an aspect of the present invention, there is provided an optical voltage measuring apparatus comprising: a main circuit conductor, a dielectric body which insulatingly supports the main circuit conductor and is fixed to a grounding member, a buried electrode buried in the dielectric body, and an electro-optic element which is connected to the buried electrode and measures a voltage of the main circuit ------------conductor, wherein a voltage, which is divided by an electrostatic capacitance ratio between an electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and an electrostatic capacitance, which is created between the buried electrode and the grounding member, is applied to the electro-optic element.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
FIG. 1 is a cross-sectional view of an insulation spacer which functions as a conventional voltage divider;
FIG. 2 is a cross-sectional view of an insulation spacer which functions as a voltage divider according to Embodiment 1 of the present invention; and FIG. 3 is a cross-sectional view of a post spacer which functions as a voltage divider according to Embodiment 2 of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will now be described with reference to the accompanying drawings.
[Embodiment 1]
To begin with, an optical voltage measuring apparatus according to Embodiment 1 of the present invention is described with reference to FIG. 2.
FIG. 2 is a cross-sectional view of an insulation spacer which functions as a voltage divider according to Embodiment 1 of the invention. In FIG. 2, the structural parts common to those in the prior art are denoted by like reference numerals.
As is shown in FIG. 2, a main circuit conductor 1 of a gas-insulation switching device is supported by and fixed to a cone-shaped insulation spacer 2, and is insulated from a cylindrical tank (grounding member) 3 which is at a ground potential. The insulation spacer 2 has a first dielectric body 4 which is formed by injecting an epoxy resin. An annular buried electrode 6 is buried in the first dielectric body 4 on the tank 3 side. An annular buried metal 7 is provided at both ends of an outer peripheral portion, and is airtightly fixed to the end of the tank 3. An insulation gas is filled in the tank 3.
One end of an electro-optic element 20, which is formed by using a single crystal of BGO, BSO, etc., is connected to the buried electrode 6, and the other end of the electro-optic element 20 is grounded.
Measurement light (optical signal) for measuring a voltage is made incident on the electro-optic element 20 via a light source driving device 21, a light source 22 such as a light-emitting diode, an optical fiber 23, a light guide collimator unit 24, a polarizer 25 for converting incident light to linearly-polarized light, and a 1/4 wavelength plate 26 which converts linearly-polarized light to circularly-polarized light.
The electro-optic element 20 converts the incident circularly-polarized light to elliptically-polarized light in accordance with the intensity of electric field, and emits measurement light. The measurement light passes through an analyzer 27, and only one polarization component is emitted. The emitted light is guided to an optical fiber 29 via a light reception collimator unit 28, and is sent to a detector 30. The detector 30 converts the measurement light to an electric signal, and a measured voltage is calculated by an electronic circuit 31. The components from the light guide collimator unit 24 to the light reception collimator unit 28 are accommodated in a shield case 32 which eliminates the effect of electric field.
In the insulation spacer 2, a primary-side electrostatic capacitance 10 is created between the main circuit conductor 1 and the buried electrode 6, and a secondary-side electrostatic capacitance 33 is created between the buried electrode 6 and the tank 3.
Accordingly, a voltage, which is divided by a compound capacitance of the primary-side electrostatic capacitance 10, the electrostatic capacitance of the electro-optic element 20 itself and the secondary-side electrostatic capacitance 33, is applied to the electro-optic element 20.
In this case, the electrostatic capacitance of the electro-optic element 20 is much smaller than the secondary-side electrostatic capacitance 33, and the voltage division ratio is substantially determined by the secondary-side electrostatic capacitance 33. The reason for this is that despite the specific dielectric constant of the electro-optic element 20 being higher than that of the epoxy resin, the electrode disposition between the buried electrode 6 and the tank 3 is a coaxial electrode arrangement, and the mutually opposed electrode area becomes much greater than the area of the electro-optic element 20. In the insulation spacer 2 with a diameter of about 300 mm, the electrostatic capacitance ratio between the electro-optic element 20 and the secondary-side electrostatic capacitance 33 is 100 or more.
Thereby, the voltage that is divided by the electrostatic capacitance ratio between the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 is applied to the electro-optic element 20, and the main circuit voltage can be measured. The primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 are _ 9 _ formed of the same epoxy resin, and have similar variations in electrostatic capacitance due to temperature variations. Since a predetermined low humidity is constantly kept within the tank 3, the inside of the tank 3 is not affected by humidity.
Specifically, the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 are exposed in the same environment.
Although a floating electrostatic capacitance in the insulation gas is added to the primary-side electrostatic capacitance 10, there is no influence by environmental characteristics, similarly with the above-described case.
According to the optical voltage measuring apparatus of Embodiment 1, the buried electrode 6 is buried in the first dielectric body 4 that is formed of the epoxy resin, and the voltage that is applied to the electro-optic element 20 is divided by the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33, which are formed of the same epoxy resin. Therefore, the electrostatic capacitance ratio is not affected by the environmental characteristics such as temperature and humidity, and the main circuit voltage can be measured with high precision.
[Embodiment 2]
Next, an optical voltage measuring apparatus according to Embodiment 2 of the present invention is described with reference to FIG. 3. FIG. 3 is a cross-sectional view of a post spacer which functions as a voltage divider according to Embodiment 2 of the invention. Embodiment 2 differs from Embodiment 1 with respect to the insulator that functions as the voltage divider. In FIG. 3, the structural parts common to those in Embodiment 1 are denoted by like reference numerals, and a detailed description thereof is omitted.
As shown in FIG. 3, a main circuit conductor 1, which is coupled by a coupling 35, is supported and fixed by a post spacer 36 which has a first dielectric body 4 formed of an epoxy resin. A main-circuit-side buried metal 37 is buried in the first electric body 4 on the coupling 35 side. A cylindrical ground-side buried metal 38 is buried in the first electric body 4 on the tank 3 side, and the buried metal 38 is fixed to the tank 3. A columnar buried electrode 39 for dividing the main circuit voltage is buried in a substantially central part of the ground-side buried metal 38. An electro-optic element is connected to the buried electrode 39.
Thereby, a primary-side electrostatic capacitance 40 is formed between the main-circuit-side buried metal 37 and the buried electrode 39, and a secondary-side electrostatic capacitance 41 is formed between the buried electrode 39 and the ground-side buried metal 38, and thus the main circuit voltage is divided. The buried electrode 39 and the ground-side buried metal 38 are disposed in a coaxial electrode arrangement,= and the secondary-side electrostatic capacitance 41 is greater than the primary-side electrostatic capacitance 40. Since these electrostatic capacitances 40 and 41 are created by the first dielectric body 4 of the same insulation material and are used in the same environment, there is no influence by the environmental characteristics.
According to the optical voltage measuring apparatus of Embodiment 2, the same advantageous effects as in Embodiment 1 can be obtained.
The present invention is not limited to the above-described embodiments, and the invention can be variously modified and implemented without departing from the spirit of the invention. In the above-described embodiments, the first dielectric body 4 has been described as being formed by using a general epoxy resin. If inorganic material, such as silica, is added, the temperature characteristics can be relaxed.
In addition, the specific dielectric constant can easily be adjusted by the mixture ratio, and the range of choices of electrostatic capacitance can be increased. Moreover, other insulation materials, which are used in electric appliances, such as polycarbonate resin, polyester resin and phenol resin, can be used.
In the case where use is made in a managed electric room and a surface creeping leak current due to contamination and wetting is negligible, the use in the air is applicable. Specifically, the main circuit voltage can precisely be measured in the case where the primary-side electrostatic capacitance 10, 40 and the secondary-side electrostatic capacitance 33, 41 are formed of the same insulation material, use is made in the same environment and surface creepage insulation strength is high.
As has been described above in detail, according to the present invention, the primary-side electrostatic capacitance and the secondary-side electrostatic capacitance are formed of the same insulation material and the voltage that is divided by the electrostatic capacitance ratio therebetween is connected to the electro-optic element. Therefore, the main circuit voltage can be measured with high precision, without the electrostatic capacitance ratio being affected by environmental characteristics such as temperature and humidity.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
To begin with, an optical voltage measuring apparatus according to Embodiment 1 of the present invention is described with reference to FIG. 2.
FIG. 2 is a cross-sectional view of an insulation spacer which functions as a voltage divider according to Embodiment 1 of the invention. In FIG. 2, the structural parts common to those in the prior art are denoted by like reference numerals.
As is shown in FIG. 2, a main circuit conductor 1 of a gas-insulation switching device is supported by and fixed to a cone-shaped insulation spacer 2, and is insulated from a cylindrical tank (grounding member) 3 which is at a ground potential. The insulation spacer 2 has a first dielectric body 4 which is formed by injecting an epoxy resin. An annular buried electrode 6 is buried in the first dielectric body 4 on the tank 3 side. An annular buried metal 7 is provided at both ends of an outer peripheral portion, and is airtightly fixed to the end of the tank 3. An insulation gas is filled in the tank 3.
One end of an electro-optic element 20, which is formed by using a single crystal of BGO, BSO, etc., is connected to the buried electrode 6, and the other end of the electro-optic element 20 is grounded.
Measurement light (optical signal) for measuring a voltage is made incident on the electro-optic element 20 via a light source driving device 21, a light source 22 such as a light-emitting diode, an optical fiber 23, a light guide collimator unit 24, a polarizer 25 for converting incident light to linearly-polarized light, and a 1/4 wavelength plate 26 which converts linearly-polarized light to circularly-polarized light.
The electro-optic element 20 converts the incident circularly-polarized light to elliptically-polarized light in accordance with the intensity of electric field, and emits measurement light. The measurement light passes through an analyzer 27, and only one polarization component is emitted. The emitted light is guided to an optical fiber 29 via a light reception collimator unit 28, and is sent to a detector 30. The detector 30 converts the measurement light to an electric signal, and a measured voltage is calculated by an electronic circuit 31. The components from the light guide collimator unit 24 to the light reception collimator unit 28 are accommodated in a shield case 32 which eliminates the effect of electric field.
In the insulation spacer 2, a primary-side electrostatic capacitance 10 is created between the main circuit conductor 1 and the buried electrode 6, and a secondary-side electrostatic capacitance 33 is created between the buried electrode 6 and the tank 3.
Accordingly, a voltage, which is divided by a compound capacitance of the primary-side electrostatic capacitance 10, the electrostatic capacitance of the electro-optic element 20 itself and the secondary-side electrostatic capacitance 33, is applied to the electro-optic element 20.
In this case, the electrostatic capacitance of the electro-optic element 20 is much smaller than the secondary-side electrostatic capacitance 33, and the voltage division ratio is substantially determined by the secondary-side electrostatic capacitance 33. The reason for this is that despite the specific dielectric constant of the electro-optic element 20 being higher than that of the epoxy resin, the electrode disposition between the buried electrode 6 and the tank 3 is a coaxial electrode arrangement, and the mutually opposed electrode area becomes much greater than the area of the electro-optic element 20. In the insulation spacer 2 with a diameter of about 300 mm, the electrostatic capacitance ratio between the electro-optic element 20 and the secondary-side electrostatic capacitance 33 is 100 or more.
Thereby, the voltage that is divided by the electrostatic capacitance ratio between the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 is applied to the electro-optic element 20, and the main circuit voltage can be measured. The primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 are _ 9 _ formed of the same epoxy resin, and have similar variations in electrostatic capacitance due to temperature variations. Since a predetermined low humidity is constantly kept within the tank 3, the inside of the tank 3 is not affected by humidity.
Specifically, the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33 are exposed in the same environment.
Although a floating electrostatic capacitance in the insulation gas is added to the primary-side electrostatic capacitance 10, there is no influence by environmental characteristics, similarly with the above-described case.
According to the optical voltage measuring apparatus of Embodiment 1, the buried electrode 6 is buried in the first dielectric body 4 that is formed of the epoxy resin, and the voltage that is applied to the electro-optic element 20 is divided by the primary-side electrostatic capacitance 10 and secondary-side electrostatic capacitance 33, which are formed of the same epoxy resin. Therefore, the electrostatic capacitance ratio is not affected by the environmental characteristics such as temperature and humidity, and the main circuit voltage can be measured with high precision.
[Embodiment 2]
Next, an optical voltage measuring apparatus according to Embodiment 2 of the present invention is described with reference to FIG. 3. FIG. 3 is a cross-sectional view of a post spacer which functions as a voltage divider according to Embodiment 2 of the invention. Embodiment 2 differs from Embodiment 1 with respect to the insulator that functions as the voltage divider. In FIG. 3, the structural parts common to those in Embodiment 1 are denoted by like reference numerals, and a detailed description thereof is omitted.
As shown in FIG. 3, a main circuit conductor 1, which is coupled by a coupling 35, is supported and fixed by a post spacer 36 which has a first dielectric body 4 formed of an epoxy resin. A main-circuit-side buried metal 37 is buried in the first electric body 4 on the coupling 35 side. A cylindrical ground-side buried metal 38 is buried in the first electric body 4 on the tank 3 side, and the buried metal 38 is fixed to the tank 3. A columnar buried electrode 39 for dividing the main circuit voltage is buried in a substantially central part of the ground-side buried metal 38. An electro-optic element is connected to the buried electrode 39.
Thereby, a primary-side electrostatic capacitance 40 is formed between the main-circuit-side buried metal 37 and the buried electrode 39, and a secondary-side electrostatic capacitance 41 is formed between the buried electrode 39 and the ground-side buried metal 38, and thus the main circuit voltage is divided. The buried electrode 39 and the ground-side buried metal 38 are disposed in a coaxial electrode arrangement,= and the secondary-side electrostatic capacitance 41 is greater than the primary-side electrostatic capacitance 40. Since these electrostatic capacitances 40 and 41 are created by the first dielectric body 4 of the same insulation material and are used in the same environment, there is no influence by the environmental characteristics.
According to the optical voltage measuring apparatus of Embodiment 2, the same advantageous effects as in Embodiment 1 can be obtained.
The present invention is not limited to the above-described embodiments, and the invention can be variously modified and implemented without departing from the spirit of the invention. In the above-described embodiments, the first dielectric body 4 has been described as being formed by using a general epoxy resin. If inorganic material, such as silica, is added, the temperature characteristics can be relaxed.
In addition, the specific dielectric constant can easily be adjusted by the mixture ratio, and the range of choices of electrostatic capacitance can be increased. Moreover, other insulation materials, which are used in electric appliances, such as polycarbonate resin, polyester resin and phenol resin, can be used.
In the case where use is made in a managed electric room and a surface creeping leak current due to contamination and wetting is negligible, the use in the air is applicable. Specifically, the main circuit voltage can precisely be measured in the case where the primary-side electrostatic capacitance 10, 40 and the secondary-side electrostatic capacitance 33, 41 are formed of the same insulation material, use is made in the same environment and surface creepage insulation strength is high.
As has been described above in detail, according to the present invention, the primary-side electrostatic capacitance and the secondary-side electrostatic capacitance are formed of the same insulation material and the voltage that is divided by the electrostatic capacitance ratio therebetween is connected to the electro-optic element. Therefore, the main circuit voltage can be measured with high precision, without the electrostatic capacitance ratio being affected by environmental characteristics such as temperature and humidity.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Claims (4)
1. An optical voltage measuring apparatus comprising:
a main circuit conductor;
a dielectric body which insulatingly supports the main circuit conductor and is fixed to a grounding member;
a buried electrode buried in the dielectric body;
and an electro-optic element which is connected to the buried electrode and measures a voltage of the main circuit conductor, wherein a voltage, which is divided by an electrostatic capacitance ratio between an electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and an electrostatic capacitance, which is created between the buried electrode and the grounding member, is applied to the electro-optic element.
a main circuit conductor;
a dielectric body which insulatingly supports the main circuit conductor and is fixed to a grounding member;
a buried electrode buried in the dielectric body;
and an electro-optic element which is connected to the buried electrode and measures a voltage of the main circuit conductor, wherein a voltage, which is divided by an electrostatic capacitance ratio between an electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and an electrostatic capacitance, which is created between the buried electrode and the grounding member, is applied to the electro-optic element.
2. The optical voltage measuring apparatus according to claim 1, wherein the electrostatic capacitance, which is created between the main circuit conductor and the buried electrode, and the electrostatic capacitance, which is created between the buried electrode and the grounding member, are exposed in the same environment.
3. The optical voltage measuring apparatus according to claim 1 or 2, wherein the buried electrode and the grounding member are disposed in a coaxial electrode arrangement.
4. The optical voltage measuring apparatus according to claim 1 or 2, wherein the dielectric body is an epoxy resin.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2008-233941 | 2008-09-11 | ||
| JP2008233941A JP2010068665A (en) | 2008-09-11 | 2008-09-11 | Optical voltage measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2678212A1 true CA2678212A1 (en) | 2010-03-11 |
Family
ID=41820804
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2678212 Abandoned CA2678212A1 (en) | 2008-09-11 | 2009-09-08 | Optical voltage measuring apparatus |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2010068665A (en) |
| CN (1) | CN101672868A (en) |
| CA (1) | CA2678212A1 (en) |
| CH (1) | CH699465B1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2479581A1 (en) * | 2011-01-21 | 2012-07-25 | PowerSense A/S | An AC or DC power transmission system and a method of measuring a voltage |
| CN104614118B (en) * | 2013-11-05 | 2019-01-11 | 精工爱普生株式会社 | Force checking device, robot and electronic component handling apparatus |
| CN108802469B (en) * | 2018-05-25 | 2020-12-18 | 北京航天时代光电科技有限公司 | Novel low-voltage optical voltage sensing device |
-
2008
- 2008-09-11 JP JP2008233941A patent/JP2010068665A/en active Pending
-
2009
- 2009-09-08 CH CH13922009A patent/CH699465B1/en unknown
- 2009-09-08 CA CA 2678212 patent/CA2678212A1/en not_active Abandoned
- 2009-09-11 CN CN200910174389A patent/CN101672868A/en active Pending
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| Publication number | Publication date |
|---|---|
| CN101672868A (en) | 2010-03-17 |
| CH699465B1 (en) | 2013-05-15 |
| CH699465A2 (en) | 2010-03-15 |
| JP2010068665A (en) | 2010-03-25 |
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