JPS63145974A - Detection of partial discharge of electric equipment - Google Patents

Abstract

PURPOSE:To enable detection to be surely effected by utilizing the idle channel of television broadcasting wave and detecting electromagnetic wave generated by partial discharge. CONSTITUTION:In this detector, a high frequency amplifier circuit 12 constitutes a receiver 13 for receiving television broadcasting wave. Electromagnetic wave caught by an antenna 10 is inputted to the circuit 12. The circuit 12 selects and amplifies the frequency band of the idle channel of television broadcasting wave that is not used in a region wherein detection is conducted. The output of the circuit 12 is inputted to a judging circuit 14. When the output of the circuit 12 is above a prescribed threshold level and the output Vd of a rectifying circuit 14a is above a reference voltage Vr, a comparing circuit 14b outputs detection signal indicative of the generation of partial discharge. Thus, the effect of external wave is minimized and electromagnetic wave due to the partial discharge can be surely detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a partial discharge detection method for detecting partial discharge generated within electrical equipment.

[Prior art] Between gas insulation r! 2. Description of the Related Art In power equipment such as l devices, transformers, and gas-insulated m-wires, abnormalities in the equipment are known by detecting partial discharges occurring within the equipment.

As a method to detect partial discharge that occurs in electrical equipment,
There are known methods for detecting partial discharge sounds using ultrasonic sensors attached to the case of electrical equipment, and methods for detecting electromagnetic waves generated by partial discharges.

[Problems to be Solved by the Invention] When detecting a partial discharge using the above method, it is necessary to distinguish between a signal generated by the partial discharge and noise. Therefore, in addition to obtaining a partial discharge detection signal by detecting the ultrasonic waves that occur when a partial discharge occurs in an electrical device, we also detect the fIi current that flows from the metal case of the electrical device through the grounding wire when a partial discharge occurs to discharge the electrical device. A method is adopted in which a current detection signal is obtained and the partial discharge detection signal is taken in only when the discharge current detection signal is generated.

However, since the ultrasonic waves generated by partial discharge are weak,
If there is a lot of noise such as the vibration sound of a separate device, it may be difficult to clearly distinguish the partial discharge detection signal from the external noise even with the above method, making it difficult to improve detection accuracy. Ta.

In addition, in the method of detecting electromagnetic waves generated by partial discharge,
Although it is possible to avoid the effects of equipment vibrations and noise from the surrounding environment, in this case external radio waves may interfere with detection. In other words, the electromagnetic waves generated by partial discharge are extremely weak, so when artificial radio waves used in television, radio, wireless communication, etc. enter the detection circuit as foreign radio waves, it is difficult to distinguish between the foreign radio waves and the electromagnetic waves caused by partial discharge. reception is not possible, and partial discharge detection will fail.

When conducting dielectric strength tests by detecting electromagnetic waves generated by partial discharges in electrical equipment, the electrical equipment and detection equipment are placed in a building that is shielded from radio waves. These methods can only be implemented in factories that manufacture electrical equipment, and cannot be used when installing electrical equipment on-site or while it is in operation.

An object of the present invention is to reduce the influence of external radio waves as much as possible without using a building or the like that is shielded from external radio waves, and to make it possible to reliably detect electromagnetic waves caused by partial discharge. The purpose of this invention is to propose a discharge detection method.

[Means for Solving the Problems] The present invention provides a partial discharge detection method for detecting partial discharges by detecting RI electromagnetic waves generated by partial discharges generated in electrical equipment, and is applicable to televisions, radios, wireless communications, etc. This makes it possible to detect partial discharges without being affected by the artificial external radio waves used.

Therefore, in the present invention, the electromagnetic waves generated by the partial discharge are captured by appropriate means, and the electromagnetic waves are inputted to a receiving device for receiving television broadcasting radio waves, and the receiving device receives the television broadcasting radio waves. The electromagnetic waves are detected by receiving an empty channel.

[Operation of the Invention] As is well known, the frequency band used for television broadcasting is 90 MHz to 770 MHz, and this frequency band is divided into 1 to 62 channels. and,
Not all of these channels are used in each region, and a considerable number of channels remain vacant.

Since it is not allowed to use the frequency band of an empty channel for other communications, there are no artificially generated strong radio waves on the empty channel 17, and there are unavoidable radio waves such as static electricity. Just do it. Therefore, it can be said that an empty channel of radio waves for television broadcasting is a frequency band with the least noise when detecting electromagnetic waves caused by partial discharge.

Therefore, as in the present invention, if an empty channel of television broadcasting radio waves is used to detect the frequency component of electromagnetic waves generated by partial discharge that falls within the frequency band of the empty channel, Electromagnetic waves caused by partial discharge can be reliably detected while minimizing the influence of radio waves.

Note that when there are a plurality of empty channels, it is natural to select an empty channel in a frequency band that matches the frequency components that are included in many electromagnetic waves.

[Example] The present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show the configuration of an apparatus for carrying out the method of the present invention. In FIG. 2, 1 is a tubular metal container 2.
This is a gas insulated bus bar constructed by housing conductors 3 in containers 2a, 2b, . . . , and the conductors 3 are supported by insulating spacers 4 provided between containers 2a, 2b, .

Here, conductor 3 and capacitor 2a.

2b, . . . , an AC voltage of 50H2 or 60H2 is applied. YongFj2a, 2b.

... are grounded by a grounding wire 5, and when a partial discharge (corona discharge) 6 occurs between the conductor 3 and, for example, the capacitor 2a, a partial discharge current flows through the grounding wire 5. Further, when a partial discharge occurs, the conductor 3 and the ground wire 5 act as an antenna, and electromagnetic waves 7 are radiated.

In the present invention, the occurrence of partial discharge is detected by detecting this electromagnetic wave, but the detection of this electromagnetic wave is carried out using the antenna 10 placed inside the container 2a or the grounding wire 5.
This can be done by an induction coil 11 coupled to.

Further, the antenna 10 can be inserted into a hole provided in the flange portion of the insulating spacer 4, or can be buried inside the insulating spacer when the insulating spacer is molded.

Although various means for detecting the electromagnetic waves generated by the partial discharge as described above can be considered, in the following explanation, it is assumed that the electromagnetic waves are detected by the antenna 10 arranged inside the container 2a.

In FIG. 1, reference numeral 12 denotes a high frequency amplification circuit for selectively amplifying input signals, and in this embodiment, this amplification circuit 12 constitutes a receiving device 13 for television broadcast radio waves. The electromagnetic waves captured by the antenna 10 are transmitted to a high frequency amplification circuit 12.
The high frequency amplification circuit selects and amplifies the frequency band of an empty channel of television broadcasting radio waves that is not used in the area where the detection is performed. If there are multiple empty channels, select a channel that includes as many frequency components of electromagnetic waves generated by partial discharge as possible within the band. The output of this amplifier circuit 12 is input to a determination circuit 14, and the determination circuit determines the presence or absence of partial discharge.

The determination circuit 14 is a circuit that determines that partial discharge has occurred when an electromagnetic wave of a predetermined threshold level or higher is detected, and this circuit includes, for example, a rectifier circuit 14a that rectifies the output of the amplifier circuit 12, and a rectifier circuit 14a. and a comparator circuit 14b that compares the output voltage Vd of the amplifier circuit 12 with the M quasi-voltage Vr that provides a threshold level. When the output of the circuit 14a becomes equal to or higher than the reference voltage Vr, the comparison circuit 14b outputs a detection signal indicating that a partial discharge has occurred.

As mentioned above, there are no artificially generated strong radio waves in the empty channels of television broadcasting radio waves,
This is the frequency band with the least noise when detecting electromagnetic waves generated by partial discharges, so as mentioned above, empty channels of television broadcasting radio waves are used to detect the frequency components of electromagnetic waves generated by partial discharges. If you try to detect components that fall within the frequency band of an empty channel,
Electromagnetic waves caused by partial discharge can be reliably detected while minimizing the influence of external radio waves.

In the above example, the receiving device 13 is configured only by the high frequency amplification circuit 12, but the output of the high frequency amplification circuit 12 may be converted to an intermediate frequency and then input to the determination circuit after performing intermediate frequency amplification. good.

FIG. 3 shows another example of the configuration of an apparatus for carrying out the method of the present invention. In this embodiment, a high frequency amplifier circuit 12
The output of the mixing circuit 16 is input to the mixing circuit 16 together with the output of the local oscillator 15, and the output of the mixing circuit 16 is input to the AM detection circuit 17. The output of the AM detection circuit 17 is input to the filter circuit 18, and the output of the filter circuit is input to the determination circuit 14.
has been entered. In this example, the receiving device 13 includes a high frequency amplifier circuit 12, an oscillator 15, a mixing circuit 16, an AM detection circuit 17, and a filter circuit 18.

In the case of the apparatus shown in FIG. 3, the high frequency amplifier circuit 12 selectively receives and amplifies the frequency band of an empty channel, and then the output of the amplifier circuit 12 is inputted to the mixing circuit 16 together with the output of the oscillator 15 to generate an intermediate frequency signal. Convert to signal Vl11,
The intermediate frequency signal vm is subjected to AM detection to obtain a low frequency signal (audio frequency signal>Va. When electromagnetic waves due to partial discharge are received and detected in this way, the obtained low frequency signal has no power to be applied to electrical equipment. It is clear that many signals with a frequency twice the frequency of the AC voltage being detected are included.Therefore, in this embodiment, the low frequency signal Va obtained from the AM detection circuit 17 is sent to the filter circuit 18. Through the filter circuit, a signal with twice the frequency of the AC voltage (100H2 or 120 l-1z in the case of power equipment) is extracted as the partial discharge detection signal f.If partial discharge has occurred, the filter circuit A partial discharge detection signal ``r'' of a predetermined level or higher is output to the output side of the circuit 18. This detection signal V'' is input to the determination circuit 14 and compared with a predetermined threshold level, It is determined that a partial discharge has occurred in the electrical equipment when the voltage is above the threshold level.

FIG. 4 shows still another configuration example of the apparatus for implementing the method of the present invention. In this example, a gate circuit 19 is provided on the input side of the determination circuit 14, and as in the example of FIG. The output of the filter circuit 17 of the configured receiving device 13 is input to the determination circuit 14 through this one gate circuit. In addition, in this example, when partial discharge occurs in electrical equipment, the capacity B2a
A current detector (for example, a current transformer) 20 is provided to detect the discharge current flowing through the grounding wire of the current detector 20.
The output is amplified by an amplifier 21 and then input to a rectifier circuit 22. The output of the rectifier circuit 22 is connected to the gate circuit 19
is given as a trigger signal Vt, and the partial discharge detection signal V[ is input to the determination circuit 14 through the gate circuit 19 only when the partial discharge detection signal f is obtained while the partial discharge current is being detected. It has become.

In the case of the device shown in FIG. 4, only when the partial discharge detection signal Vf is sent from the filter circuit 18 in a state where a partial discharge current is detected, the determination circuit 1 passes through one gate circuit.
4, the detection accuracy can be greatly improved.

In carrying out the method of the present invention, it is of course possible to use a tuner for receiving television broadcasting as a receiving device, and to determine the presence or absence of partial discharge from its output.

In the above explanation, a gas insulated bus bar was used as an example of an electric R unit, but the method of the present invention can also be applied to other electrical equipment such as transformers and gas insulated switchgear. It's true.

[Effects of Charging] As described above, according to the present invention, the electromagnetic waves generated by partial discharge are detected using empty channels of television broadcasting radio waves where no artificial radio waves exist. This has the advantage that electromagnetic waves caused by partial discharge can be reliably detected while minimizing the influence of radio waves.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an apparatus for carrying out the method of the present invention, Fig. 2 is a block diagram showing an example of electrical equipment together with electromagnetic wave detection means, and Figs. 3 and 4 are respectively the method of the present invention. FIG. 2 is a block diagram showing another configuration example of a device that implements. 1...Gas insulated m-wire (electrical separate), 2a, 2b...
Metal container, 3... Conductor, 4... Insulating spacer, 6...
... Partial discharge, 7... Electromagnetic waves, 10... Antenna (
11... Induction coil (electromagnetic wave detection means), 12... High frequency amplification circuit, 13... Judgment circuit, 14... Receiving device, 15... Oscillator, 16...
-Mixing circuit, 17...AM detection circuit, 18...filter circuit. Procedural amendment (March 9, 1988, Kunio Ogawa, Commissioner of the Japan Patent Office, 1, Indication of case: Japanese Patent Application No. 61-293251 2, Title of invention: Method for detecting partial discharge in electrical equipment 3, Make amendments) Patent applicant (394) Nissin Electric Co., Ltd. 4, Agent 6th Floor 5, Expenditure Building, 4-31-6 Shinbashi, Minato-ku, Tokyo, Column 6 for a brief explanation of the drawing of the detailed description subject to amendment , "13...determination circuit, 14...receiving device," in page 13, lines 13 to 14 of the specification of amendment contents was changed to "13...receiving device, 14...determination circuit," Correct.

Claims (1)

[Scope of Claims] A partial discharge detection method for detecting electromagnetic waves generated by a partial discharge generated in an electrical device, comprising: a receiving device capable of capturing the electromagnetic waves and receiving radio waves for television broadcasting; , and detecting the electromagnetic wave by receiving an empty channel of television broadcasting radio waves by the receiving device.