JPS6355473A - Detecting device for internal abnormality of electrical equipment - Google Patents

Abstract

PURPOSE:To improve detection accuracy for a partial discharge by constituting the titled device so that a grounding conductor for grounding a conductive container, and a detector for detecting an electric signal flowing through the grounding conductor are provided, and sampling of a vibration waveform is started by a signal which has been detected by the detector. CONSTITUTION:In a conductive container 1, insulating gas G, and a conductor 2 in the axial length direction in the container 1 are contained, and to the outside surface of the container 1, a vibrometer 4 and a grounding conductor l are attached. A signal which has been detected by the vibrometer 4 is amplified 5, A/D-converted 6a and stored 6b. On the other hand, a signal which has been detected 15 through the grounding conductor l is applied to a sampling command part 10 through a filter 20. In the command part 10, in case when an inputted signal is larger than a threshold value, a sampling command signal is generated. Whenever this command signal is inputted, the data which has been brought to sampling are stored 6b. In an arithmetic part 7, the data which has been stored already and the data which has been inputted newly are added, and also, brought to a cumulative addition. Subsequently, its accumulated value is given to a deciding part 8, and whether an internal abnormality of an electrical equipment exists or not is decided.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for detecting abnormalities such as partial discharges in electrical equipment, and more specifically, for detecting partial discharges occurring inside electrical equipment with high accuracy. This invention relates to an internal abnormality detection device.

[Prior art]

A bus bar in a gas insulated switchgear (GIS) has an insulating gas and a conductor arranged in a metal pipe, and is generally constructed as shown in FIG. 4. Such an internal abnormality detection device for electrical equipment is shown, for example, in Japanese Patent Application No. 61-37774. In FIG. 4, a circle for supporting the conductor 2 disposed inside the metal tubes 1, 1 is shown between the connecting flanges 1a and 18 of the metal tubes 1, 1, which are filled with insulating gas G. Both metal tubes 1.degree. 1 are connected to each other with a peripheral edge 3a of a plate-shaped support insulator 30 interposed therebetween. In order to detect the partial discharge generated in the conductor 2 inside the metal tube 1, a vibration meter 4 is attached to the outer surface of the metal tube 1, and the signal detected by the vibration meter 4 is transmitted via the amplifier 5 to the A /D conversion section 6a and memory section 6b. The signal sampled by the sampling section 6 is given to the determination section 8 via the calculation section 7. The sampling command unit 10 creates a signal that is synchronized with the zero point of the AC voltage corresponding to the AC voltage applied to the conductor 2, and uses this signal to command the sampling unit 6 to start sampling. .

The detection operation by this internal abnormality detection device is as follows. Now, if a partial discharge occurs in the conductor 2 as shown in FIG. The sampling command unit 10 gives the sampling unit 6 a signal synchronized with the time when the AC voltage is zero,
As a result, the vibration meter 4 starts sampling the signal detected and amplified by the amplifying section 5. That is, each time a sampling command signal is input from the sampling command unit 10, sampling is started n times (for example, 1000 times) at an extremely short cycle (for example, 10 μs). FIG. 5 (tel) shows an enlarged sampling state within the light frame in FIG. Then, such sampling is repeated N times. Data obtained by one sampling is sequentially stored in n memory sections 6b of the sampling section 6. The arithmetic unit 7 also has n memories, and repeats the operation of reading n sampling values from the memory unit 6b, cumulatively adding their absolute values one after another, and storing them in the memory.

The cumulative value obtained by repeating data sampling and addition N times in this way is the same as the waveform detected by the vibration type 4 at the same period as the sampling command signal given in synchronization with the zero point of the AC voltage. The waveform will be emphasized as shown in FIG. 5+d+, and the partial discharge generated within the electrical equipment can be clearly detected.

[Problem that the invention seeks to solve]

The above-described abnormality detection device for detecting partial discharge occurring in the bus bar can reliably detect partial discharge occurring in synchronization with the voltage cycle. However, since partial discharges do not always occur in synchronization with the voltage cycle, there is a problem that abnormalities due to partial discharges that occur asynchronously cannot be detected.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an internal abnormality detection device that can detect with high precision even abnormalities caused by partial discharges that occur in electrical equipment without synchronization with the voltage cycle.

[Means for solving problems]

The internal abnormality detection device for electrical equipment of the present invention includes a grounding wire that grounds a conductive container and a detector that detects an electrical signal flowing through the grounding wire, and samples a vibration waveform using the signal detected by the detector. The configuration is to start.

[Effect]

Partial discharge occurs around a conductor in a conductive container to which a high voltage is applied due to insulation deterioration or the like. The mechanical vibration of the conductive container due to this partial discharge is detected by a vibration meter. On the other hand, an electric signal such as a high frequency current due to the generated partial discharge flows through a grounding wire that grounds the conductive container. This electrical signal is detected to start sampling the vibration waveform of the mechanical vibration of the conductive container, and a large number of samplings are performed.

Repeated sampling is performed in the same manner, the sampling data is cumulatively added, and an internal abnormality is determined based on the cumulative value.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a block diagram of an internal abnormality detection device according to the present invention applied to a busbar.

In FIG. 1, an electrically conductive container 1.1 houses an insulating gas G and a conductor 2 disposed at the center of the electrically conductive container 1 along the axial direction. The conductor 2 is supported by airtightly penetrating the center of a support insulator 3 which has a disk shape and has a tapered surface with its center slightly deviated to one side from its periphery. The peripheral edge 3a of this supporting insulator 3 is connected to the conductive container 1.
It is interposed between the connecting flanges la and la of No. 1,
Both electrically conductive containers 1.1 are connected with a support insulator 3 in between.

A vibration meter 4 for detecting mechanical vibrations is attached to the outer surface of the conductive container 1.1. The signal detected by this vibration meter 4 is given to an amplifying section 5, and the signal amplified by the amplifying section 5 is given to a memory section 6b via an A/D converting section 6a of a sampling section 6. On the other hand, a ground wire is connected to the conductive container 1 to which the vibration meter 4 is attached! One end is connected and the other end is grounded. The grounding wire l is provided with a detector 15 consisting of a current transformer configured to detect the high frequency current flowing through the grounding wire l. The signal detected by the detector 15 is provided to the sampling command unit 10 via a filter 20 that passes high frequency components. The sampling command unit 10 compares the level of the signal input from the filter 20 with a threshold level determined as a level at which it can be determined that partial discharge has occurred, and determines that a signal with a level higher than the threshold level is input. A sampling command signal is issued when the In other words, when a high-frequency electric signal flows through the ground line 1 due to partial discharge occurring within the conductive container 1, a sampling command signal is given to the sampling section 6. The sampling unit 6 performs a large number of samplings at a short predetermined cycle each time a sampling command signal is input. Then, the sampled data is sequentially stored in n memory sections 6b of the sampling section 6. The calculation unit 8 adds the already stored data and the newly sampled data. The sampling unit 6 and the calculation unit 7 also repeat such data sampling and addition N times to cumulatively add the data. Then, the cumulative value is given to the determining section 8, and the determining section 8 determines whether or not there is an internal abnormality in the electrical equipment based on the result.

When an internal abnormality detection device configured in this manner is installed, for example, on the busbar of a gas-insulated switchgear, it is possible to detect a partial discharge as shown in FIG. The partial discharge causes mechanical vibration in the conductive container 1 as shown in Fig. 2, and this vibration is detected by the vibration meter 4.
is detected. Also, due to the partial discharge, I! A high frequency current as shown in FIG. 2 IC) flows and is detected by the detector 15. The level of the signal detected by the detector 15 is compared in the sampling command section 10 with a predetermined threshold value to determine partial discharge if it is higher than that, and when it exceeds the threshold, the sampling command section 10 starts sampling. A signal is given to the sampling section 6 to command the following. The sampling section 6 samples the mechanical vibration signal once at an extremely short period as shown in FIG. .Dl is an enlarged view of the sampling state within the light frame in FIG. Performs cumulative addition of the absolute values of data of repeated sampling.

When such addition processing is performed, signals such as noise that have no specific time relationship with the high frequency signal detected at the ground line l are
Even if it is added every time it is sampled, it occurs at random times, so the increase in the numerical value with the number of additions is small.

On the other hand, the sampling value of the vibration waveform sampled in response to the high-frequency current generated in the grounding wire l increases each time it is added, so when the value is cumulatively added, it gradually increases, as shown in Figure 2 (e). A detected waveform as shown in is obtained.

Then, this detected waveform is given to the determining section 8, and an internal abnormality in the electrical equipment is detected by determining the magnitude of the signal level.

FIG. 3 is a block diagram showing another embodiment of the present invention,
In this embodiment, the sampling command section 10 includes a level change section 1.
0a to periodically change the threshold level described above.

By doing this, even if large noise periodically occurs on the ground line l and the signal is input to the sampling command section 10, the threshold level is raised and the sampling command signal is generated due to the noise. You can avoid it. Therefore, even if a noise signal is mixed into the high frequency current flowing through the ground line l, the influence of the noise signal can be eliminated.

In this example, the internal abnormality detection device was applied to the busbar of the gas-insulated switchgear, but it can also be applied to busbars other than the gas-insulated switchgear, or to electrical appliances such as gas-insulated transformers that house electrical equipment together with insulating gas. Widely applied to equipment,
A similar effect can be obtained.

〔effect〕

As described in detail above, the present invention determines the point at which sampling of mechanical vibrations due to partial discharge is started based on the electrical signal of partial discharge generated inside the electrical equipment, so it is synchronized with the AC voltage applied to the equipment. It is possible to accurately detect partial discharges that occur even when there is no discharge, and the detection accuracy of partial discharges can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an internal abnormality detection device according to the present invention applied to a busbar, FIG. 2 is a waveform diagram for explaining the operation of the device of the present invention, and FIG. 3 shows another embodiment of the device of the present invention. FIG. 4 is a block diagram of a conventional internal abnormality detection device applied to a busbar, and FIG. 5 is a waveform diagram for explaining the operation of the conventional device. 1... Conductive container 2... Conductor 4... Vibration meter 6
... Sampling section 7... Calculation section 8... Judgment section 10... Sampling command section 15... Detector (
Current transformer)! ...Grounding wire In the drawings, the same reference numerals are the same or indicate the phase 5 portion.

Claims (1)

[Claims] 1. A vibration meter attached to a conductive container that houses the main body of the electrical equipment, a sampling unit that repeatedly samples the signal obtained by the vibration meter, cumulatively adds the sampling values, and determines whether or not there is an internal abnormality in the equipment based on the results. an internal abnormality detection device for an electrical device, comprising: a grounding wire that grounds the conductive container; a detector that detects an electrical signal of the grounding wire; An internal abnormality detection device for an electrical device, comprising: a sampling command section that instructs the sampling section to start sampling in synchronization.