JPH0469577A - Detector for local discharge in insulation gas - Google Patents

Abstract

PURPOSE:To surely detect a local discharge by arranging an ultrasonic sensor in a hand hole and also covering the part other than the detecting surface with an ultrasonic absorbent. CONSTITUTION:The ultrasonic sensor 4 is covered with the ultrasonic absorbent (spongy insulation substance) 5 except the detecting surface and a lead wire is pulled out to the outside of the tank 1. When a part of the ultrasonic wave propagates up to the hand hole 3 inside and reaches the detecting surface of ultrasonic sensor 4, it is converted to an electrical signal. As to the ultrasonic wave caused from a wind and rain against the tank wall, the propagated ultrasonic wave is absorbed by the ultrasonic absorbent 5 around the sensor 4. Consequently, the detected ultrasonic wave is only those caused by corona discharge within the tank 1, thus the local discharge is surely detected even in the cases of wind and rain, etc.

Description

[Detailed Description of the Invention] A. Industrial Application Field The present invention is applicable to gas insulated power equipment (gas insulated switchgear, etc.)
The present invention relates to a partial discharge detection device in an insulating gas used for predictive maintenance, particularly to a partial discharge detection device in an insulating gas using an ultrasonic sensor.

B0 Summary of the invention The present invention is a partial discharge detection device in an insulating gas, which detects ultrasonic waves caused by corona discharge by providing a hand hole in the tank of gas insulated power equipment and installing an ultrasonic sensor in the hand hole. This makes it possible to increase the reliability of predictive maintenance.

C8 Conventional technology Gas-insulated power equipment, such as gas-insulated switchgear (GI
In S), predictive maintenance is performed by detecting internal partial discharge (corona discharge). As means for detecting partial discharge in the insulating gas, there are methods such as detecting ultrasonic waves generated by partial discharge with an ultrasonic sensor and detecting changes in the magnetic field with an antenna, and these methods are appropriately employed.

When detecting partial discharge in an insulating gas using ultrasonic waves,
It is common practice to place ultrasonic sensors outside the power equipment tank so that the reliability of the power equipment does not deteriorate due to the installation of the sensor. In this case, the detected ultrasonic waves are caused by mechanical vibrations generated when particles inside the tank collide with the inner surface of the tank while driving in an alternating current electric field.

D9 Problems to be Solved by the Invention However, when the ultrasonic sensor is attached to the tank wall in this way, the ultrasonic waves generated when wind and rain hit the tank wall mix in as noise.

This noise is in the same frequency band as the corona discharge sound in the gas insulated switchgear (GIS) that is transmitted to the tank, and is greater than the corona detection level.

For this reason, there are times when corona detection is impossible due to wind and rain, leading to a decline in the reliability of predictive maintenance, and an appropriate means of discrimination is desired.

An object of the present invention is to provide a partial discharge detection device in an insulating gas that can accurately detect partial discharge using ultrasonic waves.

Means for Solving the E0 Problem The present invention provides a hand hole in the tank of gas-insulated power equipment, installs an ultrasonic sensor in the hand hole, covers the area other than the detection surface with an ultrasonic absorbing material, and connects the lead to the tank. The feature is that the wire is drawn out of the tank and connected to the measuring part.

When a corona discharge occurs in the F1 working tank, ultrasonic waves are generated and propagate in multiple directions. This ultrasonic wave reaches the ultrasonic sensor and is detected.

In this case, even if ultrasonic waves are generated on the tank wall due to wind and rain, they are difficult to propagate into the insulating gas and are absorbed by the ultrasonic absorbing material surrounding the sensor. Therefore, partial discharge can be accurately detected by ultrasonic detection.

G. Examples Hereinafter, the present invention will be explained in detail based on examples shown in the drawings.

FIG. 1 shows an embodiment of the present invention, in which 1 is a tank of gas insulated power equipment, 2 is a conductor, 3 is a hand hole with a diameter of about 100 m1+ provided in the tank 1, and 4 is inside this hand hole 3. This is an ultrasonic sensor installed at This ultrasonic sensor 4 is made of ultrasonic absorbing material (
The tank 1 is covered with a sponge-like insulating material (5), and a lead wire is extended to the outside of the tank 1.

6 is a preamplifier connected to the lead wire of the ultrasonic sensor 4, 7 is a filter, 8 is a detection circuit, 9 is an A/D conversion circuit, and 10 is a CPU.

Next, regarding the operation, when a partial discharge (corona) occurs at a certain point X of the conductor 2 in the tank 1, an ultrasonic wave is generated and propagates inside the tank 1 while being reflected. When a portion of this ultrasonic wave propagates into the handhole 3 and reaches the detection surface of the ultrasonic sensor 4, it is converted into an electrical signal. This signal is transmitted to an A/D conversion circuit 9 via a preamplifier 6, a filter 7, and a detection circuit 8. Here, after A/D conversion, C
It is input to PU1.0 and processed.

On the other hand, most of the ultrasonic waves caused by wind and rain on the tank wall are reflected between metals and gases that have a large difference in acoustic impedance, so they are difficult to propagate into the insulating gas inside the tank 1, and the propagated ultrasonic waves are transmitted to the sensor 4. is absorbed by the ultrasonic absorbing material 5 around the .

Therefore, the ultrasonic waves detected by the ultrasonic sensor 4 are caused by corona discharge within the tank 1, and partial discharge can be accurately detected even in wind and rain.

FIGS. 2 to 4 each show other embodiments of the present invention.

FIG. 2 shows a case where an ultrasonic sensor 4 having a ceramic plate 4A for detecting ultrasonic waves on its detection surface is used, and the ultrasonic receiving surface becomes wider and the detection sensitivity increases.

Figure 3 shows a 3-phase bracket bus 2A as a conductor 2 in a tank 1,
2B and 2C are installed, and each bus bar 2A and 2B
A hand hole 3 is provided at a position overlooking , 2C, and an ultrasonic sensor 4 is installed inside this hand hole 3.

In this way, even if corona discharge occurs on any of the busbars 2A, 2B, or 2C, the ultrasonic waves caused by the discharge will be propagated to the ultrasonic sensor 4 without being blocked by other busbars, ensuring reliable detection. be done.

Figure 4 shows a case in which the detection range is widened, in which two ultrasonic sensors 4-1 and 4-2 are stacked in two stages, and the rear end of the ultrasonic absorber 5-1 on the previous stage is shaped like a cone. The shape is such that the ultrasonic waves propagating along the inner surface of the tank 1 (generated by particles colliding with the tank wall) are guided to the subsequent ultrasonic sensor 4-2.The latter sensor 4-2 also has a surface other than its detection surface. is covered with an ultrasonic absorbing material 5-2. The sensor 4-1.4-2 also has an electrostatic shielding screen 4 on the front of its detection surface, as shown in FIGS. 5(a) and 5(b).
-IB, 4. -2B is installed.

In this way, an ultrasonic wave caused by corona discharge at a certain point X of the conductor 2 is detected by the sensor 4-1 at the front stage. Further, the ultrasonic waves generated by the particles y along the inner surface of the tank 1 are reflected by the rear surface of the ultrasonic absorber 5-1 in the previous stage, reach the detection surface of the sensor 4-2 in the latter stage, and are detected. That is, the detection range becomes wider.

Effect of H0 invention The effects of the present invention having the above configuration are listed below.

(1) A hand hole was provided in the tank, and an ultrasonic sensor was installed inside this hand hole, and the area other than the detection surface was covered with an ultrasonic absorbing material. Ultrasonic waves can now be detected accurately, improving the reliability of predictive maintenance.

(2) By installing the sensor inside the handhole with a diameter of about 100 mm, it becomes easier to capture ultrasonic waves during corona discharge, and the shielding effect of the handhole reduces the effects of electromagnetic induction and electrostatic induction.

(3) By attaching a ceramic plate for ultrasonic detection to the detection surface, the ultrasonic reception surface can be expanded and detection sensitivity can be increased.

(4) By installing the ultrasonic sensor in a position where it can see all the conductors in the tank, corona discharge in any conductor can be accurately detected.

(5) Using a two-stage ultrasonic sensor, the rear part of the ultrasonic absorbing material in the first stage is made into a conical shape, so that the first stage detects ultrasonic waves caused by corona discharge, and the second stage detects ultrasonic waves caused by particles along the inner surface of the tank. Detection becomes possible, and the detection range can be expanded.

[Brief explanation of drawings]

FIG. 1 is a configuration explanatory diagram showing one embodiment of a partial discharge detection device in an insulating gas according to the present invention, FIGS. 2 to 4 are configuration explanatory diagrams showing other embodiments of the present invention, and FIG. (a), (
b) is a front view and a longitudinal sectional view showing the structure of an ultrasonic sensor in another embodiment (FIG. 4). 1...Tank of gas insulated power equipment, 2...Conductor, 3
... Hand hole, 4.4-1 and 4-2 ... Ultrasonic sensor, 4A ... Ceramic plate for ultrasonic detection, 5
．． 5-1 and 5-2... Ultrasonic absorber, 6... Preamplifier, 7... Filter, 8... Detection circuit, 9...
・A/D conversion circuit, 10...CPU 0 Figure 3 Imi O Oojiku ・) 0 lecture is 1 Dokawa Kasumi Figure 4 HiO Ojitake 110 lecturer Daimei Shui and 1 other person

Claims (4)

[Claims] (1) A handhole is provided in the tank of the gas-insulated power equipment, and an ultrasonic sensor is installed inside the handhole, and the area other than the detection surface is covered with an ultrasonic absorbing material, and the lead wire is pulled out of the tank and the measurement section is A partial discharge detection device in an insulating gas, characterized in that it is connected to. (2) The device for detecting partial discharge in an insulating gas according to claim 1, wherein the ultrasonic sensor is an ultrasonic sensor having a ceramic plate on a detection surface. (3) Claim 1 characterized in that the ultrasonic sensor is located at a position where all the plurality of conductors within the tank can be viewed.
Or the insulating gas partial discharge detection device according to 2. (4) The ultrasonic sensor according to claim 1, 2 or 3, wherein a two-stage ultrasonic sensor is used, and the rear part of the ultrasonic absorber covering the previous sensor is conical. Partial discharge detection device in insulating gas.