JPS59192972A - Measuring device for static electricity - Google Patents

Abstract

PURPOSE:To raise a detection potential and to detect and measure accurately and safely static electricity by storing a spherical electrode which incorporates a voltage sensor provided with a light source for intermittent irradiation in a metallic vessel with an insulating coating, and packing electric resistance material therein. CONSTITUTION:An optoelectric converting voltmeter is connected through optical fiber cables 18 and 19 to the voltage sensor 16' which uses electrooptic crystal 13 having photoelectric effect, and the light source 31 irradiates the crystal 13 intermittently with a beam through an optical fiber cable 32. The spherical electrode 41 which incorporates the sensor 16' is stored in the metallic vessel 45 coated with an insulator 44, and the electric resistance material 47 is charged in the space in the vessel 45. Therefore, a conductive path is formed between the vessel 45 and spherical electrode 41 to detect a voltage developed outside of the vessel 45 by the sensor 16', and the display value on the optoelectric voltmeter is read through the cables 18 and 19 to detect and measure accurately and safely static electricity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device for detecting static electricity in a charged fluid.

Taking a liquid, gas, powder, or other fluid that can be electrostatically charged, such as oil or fat, for example, if the oil or fat is transported by pipe and stored in a storage tank, the oil or fat will flow through pipes, pumps, or filters. When it comes into contact with these objects, it becomes charged and becomes a high-potential charged object in the storage tank.

By the way, when measuring to know the amount stored in a storage tank or the like, a metal object such as a measuring stick may be lowered and immersed. At this time, a spark discharge occurs between the charged oil and fat and the metal body, and this may ignite the oil and fat or vaporized gas, causing an explosion and fire.

For this reason, related organizations such as fire departments and transportation are considering ways to measure the potential of static electricity in advance as a measure to prevent accidents caused by the generation of static electricity. It is hoped that a device that can measure this will emerge.

By the way, in order to know the charged state of the stored fluid, the conventional method of measuring the charged potential is as shown in FIG.
A measuring device was used in which the metal wires 1 to 4 were connected.

However, since the above-mentioned measuring device uses metal for the measurement wire, a discharge phenomenon occurs during the measurement and the electric field is disturbed, making it impossible to make accurate measurements.

In addition, there is a risk that spark discharge will occur on the curved surface, igniting the curved surface or the gas body, and causing an explosion or fire.

In order to solve the problems of measuring devices using metal leads as described above, measuring devices using a voltage sensor using an electro-optic effect and an optical fiber cable have been proposed in recent years.

The basic structure of an electric sensor (bismuth, silicon, Axide, commonly known as BSO sensor) that utilizes the electro-optic effect is as shown in Figure 2, which consists of multiple electro-optic crystals 1.
1, 12, 13.44 are arranged, and electrodes a and b are installed before and after the intermediate electro-optic crystal 13.
', b' are connected to the power supply 15 to form a voltage sensor 16, and one light from the light emitting diode 17 is sent to the electro-optic crystal 11 of the other part through the fiber optic cable 18. The optical fiber cable 1 guides the light P emitted from the electro-optic crystal 14 at the used end to the light receiving diode 20.

By the way, the height P of the light that passes through the sensor 16 is
It has the characteristics shown in FIG. 3 with respect to the voltage V applied between electrodes a and 1.

In other words, for the light intensity P when the voltage to be measured V is zero,
When a voltage of positive polarity is applied, the light intensity P becomes stronger than PO, and when a voltage of negative polarity is applied, it becomes weaker than PO.

There are two types of conventional measurement methods using the above-mentioned sensors for voltage measurement: a probe type and a spherical electrode type.

The former probe type, as shown in FIG.
Insert the probe electrode 22 into the sensor 16, connect one electrode of the sensor 16 to the probe electrode 22 with a lead wire a', and connect the other electrode to the oil tank 21 with a lead wire b'. It measures the potential difference between

In addition, in the spherical electrode type, as shown in FIG.
6 is hermetically sealed, the electrodes of Reno 1 and No. 16 are connected to both electrodes 23 and 24 with lead wires a' and b', and the spherical electrode 25 to which the optical fiber cable 18 and 19 is connected is placed in the oil A of the oil tank 26. The spherical electrode 25 is inserted so that the surface electric field of the spherical electrode 25 can be detected.

By the way, both of the above measurement methods are based on the optical fiber cable 4.
As the transmission loss of 8.49 changes over a long period of time and the output of the light emitting diode 17 changes, the light intensity Po in FIG. 3 changes. For this reason, there is a problem in that the measurement is performed as if the intensity of light P had changed because the voltage to be measured V had changed, and accurate measurement results could not be obtained.

Conventionally, when the voltage to be measured V is AC, as shown in FIG. 6, the intensity of light P is the DC component PC). By separating the current and AC components into AC components PAC and determining the modulation degree m, it was possible to ignore changes in the DC component poc.

However, in the case of static electricity, unlike in the case of alternating current as shown in Figure 6, it is not possible to separate the direct current component Poe and the alternating current component PAc corresponding to the change in the light intensity P. There is a problem in that changes in the height P directly appear as measurement errors, making it impossible to perform accurate measurements.

The present invention was made in order to solve the above-mentioned problems that occurred when measuring static electricity, and an object of the present invention is to provide a measuring device that can safely and accurately detect and measure static electricity.

The structure of this invention is that a voltage sensor equipped with a light source that intermittently irradiates a light beam via an optical fiber cable is built into a spherical electrode, and this spherical electrode is housed in a metal tank whose outer periphery is covered with an insulator. The space inside this metal tank is filled with an electrically resistive material, making it possible to measure static electricity with high precision.

Embodiments of the present invention will be described below with reference to FIGS. 7 to 1 of the accompanying drawings.
This will be explained based on Figure 2.

FIG. 7 shows a voltage sensor 16 used in the measuring device of this invention.
The same parts as those of the conventional voltage sacer shown in FIG.

The intermediate electro-optic crystal 13 provided with electrodes a and b is formed to a size with a protrusion 13' of a required size on one side of the outer periphery, and the protrusion 13 is connected to another light source 31 via an optical fiber cable 32. ' is configured to irradiate the light 33.

The electro-optic crystals 11, 12, 13 and 14 are, for example, 8
2. Eh, SjOyu. It is formed using a combination of photoconductive effect and electro-optic effect such as.

In the voltage sensor 16' shown in FIG. 7, when the protrusion 13' of the intermediate electro-optic crystal 13 is irradiated with light 33, the insulation resistance decreases due to the photoconductive effect. When the insulation resistance decreases, the charge stored between the electrodes a and 1 of the electro-optic crystal 13 decreases, and the electric charge Vab between the electrodes a and 1 decreases.

Furthermore, when the irradiation of the light 33 to the protrusion 13' is stopped, the insulation resistance is restored and the voltage Vab between the electrodes a and 1 becomes high again.

In this way, by repeating the irradiation and stopping of the light 33 on the protrusion 13', a voltage that changes in an alternating current manner as shown in FIG. 8 appears, and as shown in FIG. When a voltage such as is applied to the electro-optic crystal 13, the amount of light transmitted through the voltage hin→, 1-46' is as shown in FIG.

As shown in Figure 9, compare the output light PO while the light is irradiated and the change PAC when the irradiation light is stopped, m = P
By determining the degree of modulation using AC/PO, it is possible to determine the magnitude of the input voltage.

Therefore, by replacing the voltage sensor 16' shown in FIG. 7 with the conventional example shown in FIG. 4 or 5,
Static electricity can be detected without being affected by changes in PO (drift).

This invention uses the voltage sensor 16' as described above,
The measurement accuracy is improved by detecting an even higher electrostatic voltage, and as shown in FIGS. 10 and 11, the voltage sensor 16' is housed inside the spherical electrode 41, and the above-mentioned lens 16' are connected to the insulated electrodes 42 and 43 of the spherical N pole 41, and the spherical electrode 41 is assembled into a metal tank 45 whose outer periphery is covered with an insulator 44. A J-sized insulated pipe 4G is passed from the top of the metal tank 45 to the outside, an optical fiber cable 18, 19 for the light and voltmeter, and a protrusion 13'.
Optical fiber cables 32 for light irradiation are led out along insulated pipes 46, respectively.

The internal space of the metal tank 45 is filled with an electrically resistive material 47 such as a liquid or powder having an electrical resistance of 107 to 16'1 degree, and a kind of electrical resistance material 47 is filled between the metal [45 and the spherical electrode 41]. By forming a conductive path and lowering the resistance of the internal atmosphere of the metal tank 45, the voltage generated outside the metal tank 45 is detected by a voltage sensor.
-16' and read the display value of the optical/voltmeter via one optical fiber cable to detect and measure static electricity.

The m11 constant of the present invention has the above-mentioned configuration. For example, as shown in FIG.
This method detects and measures static electricity generated during 7.
Light is repeatedly irradiated and stopped from the light source 31 to the protrusion 13' of the electro-optic crystal 13 of the voltage sensor 16', and the PO
This method detects static electricity generated on a curved surface without being affected by changes in .

Note that if the outermost part of the metal tank 45 is covered with an insulator 44 to isolate it from the oil surface, and the metal tank 45 is floated on the oil surface for measurement, even if the curved surface changes due to oil filling, oil feeding, etc. It follows the curved surface and can safely and accurately measure viscosity without causing spark discharge between the metal tank 45 and the curved surface.

Furthermore, the measurement of static electricity is not limited to liquids such as oil, but can also be used to measure the charging state in a gas atmosphere with the risk of ignition or the charging state in flowing powder.

As described above, according to the present invention, since it has the above configuration, it has the following effects.

(1) The electro-optic crystal, which has a photoconductive effect, is irradiated with light to lower its resistance and increase the detection potential, and the space between the spherical electrode with a built-in voltage lenser and the metal tank that houses it is filled with an electrically resistive material. Since the resistance of the atmosphere inside the metal tank is lowered, the detection potential of static electricity is significantly increased, making it possible to accurately and safely detect static electricity.

(2) Since the outer periphery of the metal tank is covered with an insulator, and an optical fiber 77 (pull) is used to take out the measurement voltage and irradiate the light, there is no discharge phenomenon between the fluid to be measured and the occurrence of discharge. It is possible to safely measure static electricity even in fluids that can cause explosions or fires.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram showing a conventional static electricity measuring device, Figure 2 is a system diagram without showing the basic structure of the voltage sensor, Figure 3 is a characteristic diagram of the amount of light transmitted through the voltage sensor, and Figure 4 is the voltage sensor. Sen υ
- The first example of the conventional method using
Figure 6 is a measurement system diagram showing the second example, Figure 6 is a relationship diagram showing the input voltage and modulation degree depending on the on/off of light, and Figure 7 is a connection diagram of the voltage sensor used in this invention. FIG. 8 is an explanatory diagram showing the relationship between the applied voltage applied to the voltage sensor and time, FIG. FIG. 11 is an enlarged sectional view of the ball electrode portion shown in the above, and FIG. 12 is a simulated measurement diagram showing the state of use of the same. 11.12,13,14... Electro-optic crystal 13' ・
・Protruding part 16... Electric L [Senry-18.19
．． 32・Optical fiber cable 31...Light leakage!
a, b... Electrode Figure 1 Figure 2 Figure 8 Figure 4 Figure 9 Figure 10 Figure 12

Claims (1)

[Claims] An optical/electric conversion voltage signal 1 is connected to a voltage sensor using an electro-optic crystal with a photoconductive effect via an optical fiber cable, and a light beam is intermittently transmitted to the electro-optic crystal of the voltage sensor via the optical fiber cable. A light source for irradiation is provided, the voltage sensor is built into a spherical electrode, the spherical electrode is housed in a metal tank whose outer periphery is covered with an insulator, and the space inside the metal tank is filled with an electrically resistive material. Characteristic static electricity measuring device.