JPH01278224A - Conductive anomaly monitoring device for transformative equipment - Google Patents

Abstract

PURPOSE:To minimize the measurement error that will be caused by the direction of measurement, by providing a polarization means to polarize the incident infrared rays to the front face of an infrared camera of an infrared radiation thermometer. CONSTITUTION:When localized heating is caused due to conduction anomaly to a conductor section 7, the temperature above the anomorous section of a tank 6 is raised through insulating gas 8. In order to detect the conduction anomaly, the surface temperature distribution of the tank 6 is measured with an infrared radiation thermometer 13 composed of an infrared camera 3 and a processor 12. A Brewsten window 15 as a polarization means 14 of incident infrared rays is provided by a fitting frame 16 to the front face of the infrared camera 3. The polarized components (S waves) vertical to the plane which contains the line connecting the tank 6 to the infrared camera 3 and the normal of tank surface in the tank 6 are removed, but only the polarized components (P waves) parallel to that plane are caused to pass, so that the P waves are received with the infrared camera 3 and the temperature distribution is found.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a circuit breaker energization abnormality monitoring device, and in particular, uses an infrared radiation thermometer to measure the temperature distribution on the tank surface and detect local overheating inside. The present invention relates to a device suitable for improving the measurement accuracy of things that are measured.

[Conventional technology]

When an abnormality in energization occurs due to some reason such as incomplete closing of the circuit breaker inside a gas circuit breaker or gas-insulated switchgear, an infrared radiation thermometer is used to measure the tank surface temperature, and the abnormal temperature rise is detected as an abnormality in energization. Techniques for detecting home overheating based on are known, e.g.

It is also mentioned in Lecture Nα1331 of the National Conference of the Institute of Electrical Engineers of Japan in 1988. In such a measurement method, it has become clear that the angular distribution of emissivity affects the measurement error, as will be described later. Regarding this angular distribution itself, we have already explained that R
, Siegel et al. - Masterpiece Hem1sphere Pub
ThermalRadi published by lishing Corp
ation Heat Transfer (1981)
The way of thinking is clarified.

[Problem to be solved by the invention]

When measuring the temperature distribution on the tank surface of a gas circuit breaker using the above-mentioned infrared radiation thermometer, a problem arose in that the measurement error became large due to the influence of the background temperature. Generally, gas circuit breakers have a horizontal cylindrical shape and are installed outdoors within the premises of a substation, and the camera that measures the infrared radiation thermometer is installed on the ground, so it is impossible to view the gas circuit breaker from the horizontal direction. will increase. At this time, the measurement error becomes large, especially when the sky is clear.
The temperature at the top of the tank is observed to be low. As a result of a detailed study of this phenomenon, it was found that the following two causes were involved. One is that the infrared emissivity from the tank surface depends on the angle from the normal force direction of the tank surface, and is large in the normal direction and small in the oblique direction. An example of actual emissivity measurement is shown in Figure 2. Figure 2(a)
The horizontal axis angle 0 is shown in FIG. 2(b). This is the angle formed by the desired direction 4 of the infrared camera 3 with respect to the normal direction 2 of the tank surface 1. The emissivity ε on the vertical axis is the ratio of the actually radiated energy to the theoretical value of the radiated infrared energy when treated as a black body at the same temperature.

If the emissivity is constant regardless of the angle, it is easy to find the true value by multiplying it by a correction value obtained by an appropriate method from the results of measurements on objects made of the same material whose temperature is known, and it is usually difficult to measure. The function is built into the device. Regarding the characteristics shown in FIG. 2, the process is not simple because the emissivity differs depending on the measurement position on the tank surface of the circuit breaker, which is usually in the same cylindrical shape. The second cause is a reflection of the environmental temperature. The reflectance of an object is the complement of 1 of the emissivity, and is expressed by the relationship: reflectance = 1 - emissivity, and the greater the reflectance, the greater the reflection of infrared rays coming from the environment. At this time, for example, when the difference between the ambient temperature and the temperature of the object to be measured is small, as in indoor measurements, the error is small, but in outdoor measurements on sunny days, the temperature of the blue sky is the equivalent temperature -20° to Since the temperature difference between the temperature and the target object is as low as -40° C., the error due to reflection becomes large. When a horizontally arranged cylindrical tank is fixed, the desired angle of the infrared camera to the tank surface becomes shallower,
The error is large in the upper part, and the temperature is observed to be lower than it actually is.

An object of the present invention is to minimize measurement errors caused by measurement directions and to improve the accuracy of detecting internal energization abnormalities by accurately measuring the surface temperature distribution of a tank.

[Means to solve the problem]

The above purpose is to insert a polarizing filter in front of the infrared camera, and to connect the line connecting the measurement point and the infrared camera, and the polarization component (
This is achieved by removing the S wave), passing only the polarized light component parallel to the surface (P wave), and receiving the P wave with an infrared camera to determine the temperature distribution.

[Effect]

The behavior of infrared rays on material surfaces has already been clarified, for example, by R. Siegel et al.
here Publishing Corp, Publisher T
medical radiation heat tran
Sfer (1981) and others. According to this, the reflectance of P wave and S wave is P/(θ) and P (0) are respectively, where n2 is the refractive index of medium 2 (tank surface paint in this case), nl is medium 1 (in this case refractive index of the atmosphere).

θ is the same angle as defined in FIG. 2(b).

Since the reflectance ρ (θ) for unbiased isotropic infrared light, so-called non-polarized light, is ρ (θ) = - (ρ〃 (θ) + ρ(θ)),
These relationships are shown in Figure 3. In addition, the value of the refractive index for circuit breaker paint is empirically determined as nz/nt=1.5.
Since it agrees well with the actual measured value, that value was used here. Curves a, b, and Q in the figure are emissivities corresponding to P waves, S waves, and unpolarized light, respectively, 1-ρ // (θ) and 1-
ρ1(θ).

1-ρ(θ). In normal measurements using an infrared radiation thermometer, measurements are taken based on curve C, and emissivity of 0.9 or higher is at an angle of 62 degrees or less.
A value of 0.8 or more corresponds to an angle of 72 degrees or less. For example, when the temperature of the object to be measured is 20°C and the background temperature is 120°C, the error will be approximately 2 after applying the above correction.
℃, and corresponds to the range that can be measured at 5℃. If a polarizing filter is installed in front of the infrared camera to allow only P waves to enter, the angular distribution of emissivity will be improved to curve aa in Figure 3, and the above ranges will be reduced by 1 to 75 degrees and 79 degrees, respectively.
Spread 3 degrees and 7 degrees. As a result, in the field of view of the infrared camera looking at the cylindrical circuit breaker tank, the areas below the above emissivity are reduced to 30% and 40%, respectively, which equivalently increases the emissivity around the tank. By preventing a drop in radiant energy from the tank surface and reducing the reflection of infrared rays coming from the environment, it is possible to improve the accuracy of temperature distribution measurement on the tank surface.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The figure shows the overall configuration of a typical case where the tank surface temperature distribution of a gas circuit breaker is measured using an infrared radiation thermometer.
(Cross section) shows that a conductor portion 7 is insulated and supported in a tank 6, and an insulating gas 8 is hermetically sealed. The tank 6 is installed on the ground 11 by legs 9 and a pedestal 10. When an abnormal current flow occurs in the conductor portion 7 and local overheating occurs, the temperature above the abnormal portion of the tank 6 rises via the insulating gas 8. In order to detect this, an infrared camera 3. Furthermore, the surface temperature distribution of the tank 6 is measured by an infrared radiation thermometer 13 made up of the processing device 12. The infrared radiation thermometer 13 is a commercially available product, etc.
Generally, the ones that are available are sufficient in terms of accuracy, and in addition to the method of using a portable type to measure during regular patrols as in this example, there is also a method of using a fixed type to constantly monitor the temperature of important parts. .

In this case, a method may also be adopted in which the output of the processing device 12 is connected to a host computer and temperature changes are monitored unattended. In front of the infrared camera 3 is a polarizing means 1 for incident infrared rays.
4, a Brewster window 15 is provided by a mounting frame 16. There are other methods for the polarizing means 14, such as a wire grid type, a beam splitter type, and a quarter wavelength plate type, but the Brewster window type is used here because it is easy to make one with a relatively large diameter. I chose. In either case, the infrared region to which the infrared camera 3 is sensitive (here, 8 to 1
It is necessary to take into consideration the transmittance of 3 μm), and a zinc selenide-based material is used here. Although it is convenient to make measurements while finely adjusting the mounting direction of the Brewster window as it is configured to be rotatable, the effects of the present invention can be obtained by using it in the direction in which the P waves viewed from the tank surface are incident on the infrared camera. It will be done. The value indicated by the infrared radiation thermometer changes depending on the polarization means used to remove S waves and the transmittance of the polarization means, but the value measured by direct measurement means such as a thermocouple at a typical reference point. It is necessary to find a correction value that matches the indicated value of the infrared radiation thermometer 13.Practically speaking, it is best to input the converted emissivity into the emissivity correction function built into the infrared radiation thermometer. is easy.

FIG. 4 shows another embodiment. In the present invention, as described above,
It can measure up to a 79 degree slope of the tank surface with an accuracy of ±5℃. Generally, in the present invention, it is necessary to accurately measure the temperature in the upper part of the tank, which sensitively reacts to an abnormality in energization. In the figure, the infrared camera 3 is set using a railway bridge 17 or the like in the substation premises, and the angle θ' of the direction 4 looking toward the circuit breaker shown in the figure with respect to the normal line 2 is set to 79 degrees or less, and therefore the inclination angle is 11 degrees or more. In this example, where the upper part of the tank satisfies the above conditions and allows for accurate measurements, three infrared cameras are installed at a high place.
By installing the substation, the substation premises can be seen over a wide area, and many substation devices 18 can be monitored using the infrared cameras 3. In this embodiment, it is desirable that the direction and inclination of the infrared camera 3 as well as the attachment/detachment and rotation of the polarizing means 1 (that is, control of the plane of polarization of the incident polarized light) can be remotely controlled.

FIG. 5 shows a different embodiment of how to attach the polarizing means. The main configuration of an infrared camera is generally a scanning system 20 consisting of a window 19 and a rotating mirror. Lens 21. It consists of a detector 22. In this example, the polarizing means 14 is inserted in front of the detector 22, so that even in the sixth embodiment where a polarizing means with a small diameter can be applied, the polarizing means 1 can be rotated and controlled. It is better to make it possible to attach/detach it, and desirably, it is better to make it possible to control it by input keys from the keyboard of the processing device.

〔Effect of the invention〕

According to the present invention, it is possible to minimize measurement errors caused by measurement directions and to accurately measure the surface temperature distribution of a tank.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram showing actual measurement results that are the basis of the present invention, and FIG. 3 is a diagram showing the theoretical background that is the basis of the present invention. FIG. 4 is an overall configuration diagram of another embodiment of the invention, and FIG. 5 is a partial sectional view of another embodiment of the invention. 3... Infrared camera, 6... Tank, 13... Infrared radiation thermometer, 14... Polarizing means, 18... Substation equipment, 19... Window, 20... Scanning system, 21 ...Lens, 22...Detector. Figure 1 Figure 2 Case O Figure 4 Figure 5 20 2F 74

Claims (1)

[Scope of Claims] 1. In a device for detecting abnormal temperature rise by measuring the temperature distribution on the tank surface using an infrared radiation thermometer to detect heat generated due to an abnormality in current flow occurring inside the substation equipment, the infrared radiation temperature 1. An energization abnormality monitoring device for substation equipment, characterized in that a polarizing means for polarizing incident infrared rays is provided in front of an infrared camera of the meter. 2. The power abnormality monitoring device for power substation equipment according to claim 1, wherein the infrared camera is installed at a position looking down on the substation equipment at an angle of inclination of 11 degrees or more. 3. An infrared radiation thermometer equipped with an infrared camera consisting of a window, a scanning system, a lens, and a detector, characterized in that a polarizing means is rotatably and detachably installed between the lens and the detector. .