JP2921367B2 - Optical voltmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical voltmeter for measuring a voltage applied to a conductor of an electric device.

[0002]

2. Description of the Related Art FIG. 3 shows an example of the configuration of an optical voltage sensor of an optical voltage measuring device.

An optical voltage sensor is a polarizer 44, 1/4.
It is composed of a wave plate 45, an electro-optic crystal 46, and an analyzer 47. In the electro-optic crystal 46, transparent electrodes 48 are vapor-deposited on two opposite surfaces perpendicular to the optical path 49.

When a voltage is applied to the transparent electrode 48, the refractive index of the electro-optic crystal 46 changes according to the applied voltage due to the electro-optic effect. This change in the refractive index shows different values depending on the X direction and the Y direction.

The light incident along the optical path 49 is a polarizer 44
After that, the light is converted into circularly polarized light by the 板 wavelength plate 45. Next, the circularly polarized light passes through the electro-optic crystal 46 to which a voltage is applied, and is phase-modulated to be elliptically polarized light. Since the intensity of the elliptically polarized light is converted by the analyzer 47, the voltage applied to the electro-optic crystal 46 can be measured as the light intensity.

The voltage that can be measured by an optical voltage sensor is about several hundred volts. Therefore, when measuring a high voltage, a method is used in which the voltage is divided using an intermediate electrode, a capacitor, and the like, the divided voltage is measured, and then the voltage is converted from the division ratio.

FIG. 2 shows an example of a conventional optical voltmeter.
1 shows an optical voltmeter for measuring the voltage of a conductor 11 installed in a sealed container 10 of a gas insulating device.

[0008] An intermediate electrode 50 located inside the closed container 10 and installed around the conductor 11, a ground electrode 60 installed around the conductor 11 and installed outside the intermediate electrode 50, A lead wire 51 connecting the installed insulation terminal 12 and the optical voltage sensor 40 and the intermediate electrode 50 arranged outside the closed casing 10 via the insulation terminal 12.
And a lead 61 connecting the optical voltage sensor 40 and the ground electrode 60 via the insulating terminal 12, and a divided voltage adjusting device connected in parallel with the optical voltage sensor 40 by the lead 51 and the lead 61. A capacitor 52, a signal processing circuit 43 for calculating the voltage of the conductor 11 by transmitting and receiving an optical signal to and from the optical voltage sensor 40, a light transmitting optical fiber 41 connecting the optical voltage sensor 40 and the signal processing circuit 43, and The light receiving optical fiber 42 is used.

The intermediate electrode 50 and the ground electrode 60
Are fixed in the closed container 10 by an insulator 13 such as a spacer.

The voltage between the conductor 11 and the ground electrode 60 is
The capacitance C _T between the conductor 11 and the intermediate electrode 50, the capacitance C _S between the intermediate electrode 50 and the ground electrode 60, the capacitance C _B of the divided voltage adjusting capacitor 52, and the optical voltage sensor The voltage is divided by a capacitance C _{K of} 40. Therefore the voltage applied to the optical voltage sensor 40 can be adjusted arbitrarily by changing the capacitance C _B of the divided voltage adjustment capacitor 52.

[0011] C _T of the voltage between the conductors 11 and the ground electrode 60, C _S, C _B, the voltage of the divided several hundred volts by C _K, the insulating terminal 12 via a lead wire 51 and the lead wire 61 Through the optical voltage sensor 40. Light is supplied to the optical voltage sensor 40 from the signal processing circuit 43 by the light transmitting optical fiber 41.
Then, the light intensity is converted into light intensity by the method described above, and is sent to the signal processing circuit 43 through the light receiving optical fiber 42. In the signal processing circuit 43, the optical voltage sensor 4
The voltage applied to 0 is obtained, and the voltage of the conductor 11 is calculated from the known voltage division ratio.

[0012]

BRIEF Problem to be Solved] When not using the divided voltage adjustment capacitor 52 here, a voltage between the conductor 11 and the ground electrode 60, C _T, C _S, since it is divided by C _K When the capacitance of the optical voltage sensor 40 is constant, the voltage is applied to the optical voltage sensor 40 only by changing the distance between the conductor 11 and the intermediate electrode 50 and the distance between the intermediate electrode 50 and the ground electrode 60. The voltage can be adjusted.
However, in practice, for example, when a voltage of several hundred volts is applied to the optical voltage sensor 40 when a voltage of 72 kilovolts is applied to the conductor 11 having a diameter of 100 millimeters, the diameter of the ground electrode 60 is set to 200 millimeters.
The distance of the intermediate electrode 50 to the ground electrode 60 is about 0.
2 millimeters. It is very difficult to manufacture such an intermediate electrode 50 and a ground electrode 60. Therefore, in the conventional optical voltage measuring device, the conductor 1
When the distance between the first electrode 1 and the intermediate electrode 50 and the distance between the intermediate electrode 50 and the ground electrode 60 are distances that are easy to manufacture,
In order to be able to adjust the voltage applied to the optical voltage sensor 40, the divided voltage adjusting capacitor 52 is indispensable.

However, this conventional optical voltmeter has a drawback that the temperature characteristic of the divided voltage adjusting capacitor 52 greatly appears as a measurement error factor of the optical voltmeter.

Accordingly, the present invention improves the measurement accuracy of an optical voltmeter by obtaining a voltage to be applied to an optical voltage sensor with a structure that does not require a divided voltage adjusting capacitor.

[0015]

[MEANS FOR SOLVING THE PROBLEMS] In a closed container, a section
Leave a gap between the conductor to be
A ground electrode having at least one hole mounted therein;
A part facing the hole of this ground electrode and located on the opposite side of the conductor.
Intermediate electrode attached at a distance from the ground electrode
And the ground electrode and the intermediate electrode arranged on the intermediate electrode side.
Optical voltage sensor with poles electrically connected to voltage input terminals
Optically connected to the optical voltage sensor and
A sealed terminal attached to the wall of the container, and outside the sealed container
A signal processing circuit optically connected to the sealed terminal.
And characterized in that:

[0016]

In the optical voltmeter of the present invention having the above structure, a voltage of several hundred volts applied to the optical voltage sensor can be obtained only by the intermediate electrode without using a divided voltage adjusting capacitor. The voltage can be measured accurately without being affected by the temperature characteristics of the divided voltage adjusting capacitor.

[0017]

FIG. 1 shows an example of an optical voltmeter according to the present invention.
The intermediate electrode 20 is located inside the grounded closed container 10 of the gas-insulated equipment and is opposed to the front end surface of the conductor 11, and the conductor 11 is located between the front end surface of the conductor 11 and the intermediate electrode 20. The ground electrode 30 having the hole 32 at the opposing portion is arranged. The ground electrode 30 is electrically and mechanically connected to the closed container 10, and the intermediate electrode 20 is connected to the insulating spacer 2.
1 is fixed to the ground electrode 30. Optical voltage sensor 4
Numeral 0 is fixed to the inside of the sealed container 10 having the same potential as the ground electrode 30 via the support base 35, and its voltage input terminal is connected to the intermediate electrode 20 and the ground electrode 30. Further, the signal processing circuit 43 is disposed outside the sealed container 10 and the sealed terminal 14 is provided.
Is optically connected to the optical voltage sensor 40 by a light transmitting optical fiber 41 and a light receiving optical fiber.

When a voltage is applied to the conductor 11, an electric field is generated between the conductor 11 and the ground electrode 30. However, since the ground electrode 30 has the holes 32, a predetermined ratio is determined according to the size of the holes 32. The electric field leaks to the intermediate electrode 20 side, and a voltage is generated between the ground electrode 30 and the intermediate electrode 20 according to the distance between the conductor 11 and the ground electrode 30 and the distance between the ground electrode 30 and the intermediate electrode 20.

In the embodiment, a voltage of 72 kilovolts is applied to the conductor 11 having a diameter of 100 millimeters, and a ground electrode 30 having a thickness of 10 millimeters and having a hole 32 having a diameter of 20 millimeters is provided at a position 100 millimeters away from the end face of the conductor 11. By providing the intermediate electrode 20 having a diameter of 10 mm and a thickness of 2 mm at a position 10 mm away from the ground electrode 30,
A voltage of about 300 volts is obtained between the electrode and the intermediate electrode 20. As a result, a highly accurate voltage that does not change with temperature can be measured.

[0020]

According to the present invention, a voltage of several hundred volts applied to the optical voltage sensor can be obtained only by the intermediate electrode without using a divided voltage adjusting capacitor. The measured voltage can be accurately measured without being affected by the characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an optical voltmeter according to the present invention.

FIGS. 2A and 2B are diagrams showing an example of a conventional optical voltage measuring device, wherein FIG. 2A is a schematic sectional view in the axial direction, and FIG. 2B is a schematic sectional view in the radial direction.

FIG. 3 is a diagram illustrating an example of a configuration of an optical voltage sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Closed container 11 Conductor 20 Intermediate electrode 21 Insulating spacer 30 Ground electrode 32 Hole 35 Support base 40 Optical voltage sensor 41 Optical fiber 42 Optical fiber 43 Signal processing circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01R 15/24 G01R 15/06

Claims (1)

(57) [Claims] In a closed container, a conductor to be charged is provided.
A small space attached to the conductor facing the tip
A ground electrode having at least one hole;
The part facing the hole and located on the opposite side of the conductor
Intermediate electrode mounted at a distance from the poles and this intermediate electrode
And the ground electrode and the intermediate electrode are connected to a voltage input terminal.
And an optical voltage sensor electrically connected to the child, of the closed container connected the optical voltage sensor in optical
A sealed terminal mounted on a wall and optically connected to the sealed terminal outside the sealed container
An optical voltage measuring device comprising: a signal processing circuit ;