JPS6173502A - Contact malfunction detector of power supply conductor connector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] This invention particularly relates to a gas-insulated switchgear (hereinafter abbreviated as GiS), in which a current-carrying conductor is housed in a sealed metal container. The present invention relates to a device for detecting poor contact in conductor connections in high-voltage electrical appliances.

[Prior art and its problems]

In sealed high-voltage appliances such as GiS, in which the current-carrying conductor is housed in a sealed metal container, the joints and fastening parts of the conductor connections are completely unaffected by the outside world, so their reliability is low. Although this is extremely high, since the container is sealed, the inside cannot be seen visually, so even if an abnormality occurs due to poor contact or loosened screws in fasteners, it is difficult to detect the location. Therefore, once an accident occurs, there is a risk of serious accidents such as long-term suspension of operation. Therefore, under normal operating conditions, before an abnormality occurs inside the container,
Sensing this possibility and where it exists has become an important issue.

As a method for detecting this possibility, many methods have been proposed in the past that detect when the temperature of the connection part reaches a predetermined temperature at which it is possible to predict the occurrence of an abnormality. However, in high-voltage appliances such as GiS, there is usually a large difference between the rated current and the current flowing under normal operating conditions, and the temperature rise value is approximately proportional to the square of the current value. Therefore, even if there is an abnormality in the connection part, the temperature of the connection part will not easily reach the specified value. For example, in a substation configured to receive power through two lines, the Gi
In the case where it is necessary to stop operation of S and receive power only through GiS3 on the other line, the current flowing through GiS becomes close to the rated current, easily reaching the specified temperature, and causing an abnormality. If an abnormality is detected, the GiS must stop operation, so if the previously stopped GiS is in a state where it is impossible to restart it, this substation will no longer be able to receive power. Power supply to lower substations becomes impossible. In this way, the method of detecting temperature to prevent accidents can protect the device itself from being burnt out when an abnormality occurs, but it cannot detect the presence of an abnormality unless the temperature of the connection reaches a predetermined value. Therefore, depending on the configuration and operation of the substation, unexpected problems may occur in the operation of the substation.

Therefore, a method using, for example, an X-ray irradiation device is known as a method for detecting poor contact at a conductor connection portion in a energized state regardless of the temperature. This is from the outside of the container
A beam is irradiated to obtain an X-ray transmission image of the connection part. From this transmission image, check whether the conductors on both sides of the connection part are connected in the correct position, and whether there is any abnormal wear or deformation in the connection part. ,
It attempts to judge whether the contact condition is good or bad by looking at things like this. However, only the outline of the connection part can be observed from the Xa transmission image, which makes it virtually difficult to accurately judge whether the contact state is good or bad, and the X-ray irradiation device requires a large-capacity power source. However, there were problems in terms of economics and installation space.

Furthermore, since the X@ irradiation device needs to be operated properly to avoid radiation harm to the human body, it is necessary to report to the regulatory authority when operating the device, and it has the disadvantage that it is not always easy to operate. there were.

[Purpose of the invention]

This invention has no effect of radiation on the human body, and is therefore easy to operate, and is capable of detecting poor contact at the connection part of a current-carrying conductor housed in an airtight container without making qualitative judgments such as those based on X-ray transmission images. It can be quantitatively determined from the outside without any problems, and can be easily incorporated into a constant monitoring system that comprehensively monitors not only the contact status but also the insulation status of high-voltage appliances and the pressure of the enclosed insulating gas. The purpose of the present invention is to provide a contact failure detection device that can detect contact failure.

[Key points of the invention]

In the present invention, a poor contact detection device is arranged to face a first loop antenna provided on the inner wall side of a metal container and powered from a high frequency power source, and to be arranged opposite to this $1 loop antenna so as to be tuned to the frequency of the high frequency power source. A first piezoelectric element is connected to a second loop antenna consisting of a loop coil and a capacitor configured as shown in FIG. a second piezoelectric element disposed on the other side of the current carrying path conductor and having one electric terminal connected to the current carrying path conductor; and a second piezoelectric element disposed between the current carrying path and the metal container, the other side of the second piezoelectric element a first intermediate electrode to which an electrical terminal is connected; a second intermediate electrode disposed between the first intermediate electrode and the metal container;
voltage measuring means for measuring the voltage between the intermediate electrode of the first electrode and the metal container; Second
A high-frequency mechanical vibration is generated in the first piezoelectric element through the loop antenna, and the vibration is applied to the second piezoelectric element through the contact portion.

The voltage generated in the second piezoelectric element is detected between the second intermediate electrode and the metal container, and the detected voltage is used when the contact state of the contact portion is normal. The purpose is to achieve the above object by detecting poor contact at the connection portion by comparing the voltage.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a poor contact detection device constructed in a GiS cable connection section based on the present invention. In the figure, on the inner wall side of the sealed metal container 1, MH
High frequency power supply 2 having a frequency on the order of 2 (megahertz)
A first loop antenna 4 is attached to which power is supplied from the antenna via a coaxial cable 3, and a second loop antenna 8 is arranged directly below the first loop antenna to receive radio waves emitted from the loop antenna. , is connected to a first piezoelectric element 7 attached to the upper end surface 6a of a rod-shaped current carrying path conductor 6 screwed perpendicularly into the lead-out conductor 5 connected to the main circuit equipment of GiS. Note that the high frequency power source 2 is a magnetron pulse power source using a magnetron as a high frequency oscillation tube, for example.

When attaching the first piezoelectric element 7 to the upper end surface 6a of the current-carrying path conductor, this surface is finished with high precision,
The piezoelectric cord 7 is attached after applying a couplant such as machine oil. The pressure 1 element 7 has a function of generating high-frequency ultrasonic waves by applying a high-frequency electric field. For example, by diffusing appropriate impurities into a semiconductor piezoelectric crystal, a very thin high-resistance layer appears, and a high-frequency electric field is applied to this layer. A diffusion layer transducer that generates ultrasonic waves by concentrating the waves can be used as this piezoelectric element. Note that the second loop antenna 8
is composed of a loop coil 8a and a parallel plate electrode 8b forming a capacitor, and the inductance of the loop coil 8a and the capacitance of the parallel plate electrode 8b are selected so as to be in tune with the frequency of the high frequency power source.

A contact portion 6b having a large diameter is formed at the tip of the current-carrying path conductor 6, and a contact portion 9a between the contact piece 9 and this contact portion 6b,
Similarly, the current conducting path conductors 6 and 1o are connected to each other via this contact piece 9 and a contact portion 9b with a contact portion 10a formed at the tip of the current conducting path conductor 10 on the cable side. Here, n is a leaf spring that applies contact pressure to the contact piece 9, and is supported by a cylinder 12a surrounding the contact piece 9. The mounting base consisting of the cylinder 12a and the seat 121) is coupled to the current-carrying conductor 10 in the following manner. That is,
Reference numeral 14 in the figure is a thin metal rod having straight portions extending in the radial direction at both ends of a semicircular shape having a diameter approximately equal to the diameter of the neck portion 15 formed in the current-carrying conductor 10. symmetrically facing each other so as to be formed, and inserted into the diametrical hole 12c provided in the seat 12b,
The current-carrying path conductor 10 and the mounting base 12 are coupled by expanding the central circular portion and inserting the contact portion 10a. By establishing such a loose coupling state, the contact piece 9 can be easily tilted even when the axes of the current-carrying path conductors 10 and 6 do not coincide with each other, and the current-carrying function between the side conductors 10 and 6 is maintained. maintained normally. In addition, 13 is the side conductor 10 and 6
This is an electrostatic shield for mitigating the electric field at the connection part with the mount 12, and in this embodiment, it is formed into a cylindrical shape and is attached to the mounting base 12.

The current carrying path conductor lO is provided with a second piezoelectric element 16, one electrical terminal of which is connected to the current carrying path conductor 10, and the other electrical terminal of which is connected to a first piezoelectric element 16 formed in a cylindrical shape surrounding this conductor. It is connected to the intermediate electrode 17.

Reference numeral 18 denotes an insulating member that insulates and supports this intermediate electrode 17 from the current-carrying path conductor 10. A second intermediate electrode 19 is disposed between the first intermediate electrode 17 and the metal container Yu.
A voltage measuring means is connected between the intermediate electrode and the metal container.

The process of determining whether the contact state of the contact portion is good or bad in the energized state by the contact failure detection device configured as described above is as follows.

First, start up the high frequency power supply 2 and start the first loop antenna 4.
Power up. As a result, the high frequency radio waves emitted from the loop antenna 4 are received by the second loop antenna 8 placed on the current-carrying conductor 6 side opposite to this loop antenna, and the output voltage of this second loop antenna is is applied to the first piezoelectric element 7. The piezoelectric element 7 generates high-frequency mechanical expansion and contraction vibrations due to this applied voltage, and this vibration causes the current-carrying path conductor 6. It is transmitted to the second piezoelectric element 16 via the contact portions 9a and 9b. This stretching vibration also generates an ultrasonic wave that spreads in the radial direction through the surrounding insulating medium, such as SF, gas, and tries to influence the vibration transmitted to the second piezoelectric element 16. A shielding cylinder 21 is fixed to the current-carrying conductor 6 surrounding the first piezoelectric element 7, and prevents the spread of ultrasonic waves in the radial direction. The effect of sound waves can be ignored.

The mechanical vibrations transmitted to the second piezoelectric element 16 are converted into a high-frequency voltage within this piezoelectric element. Although it is not impossible to extract this converted voltage using a loop antenna, as in the case of the first piezoelectric element, it is interfered with by the radio waves emitted from the loop antenna 4 of the first piezoelectric element. , correct measurement results cannot be obtained. Therefore, the first intermediate electrode 17 is formed by a cylinder surrounding the second piezoelectric element 16, and this intermediate electrode 17 and the current-carrying path conductor 10 serve as both terminals of the piezoelectric element 16. The voltage generated is controlled by the capacitance formed between the first intermediate electrode 17 and the second intermediate electrode 19 formed concentrically between the intermediate electrode 17 and the container 1. In this method, the voltage is divided and taken out by the capacitance formed between the second intermediate electrode 19 and the container 1, thereby avoiding radio wave interference. That is, as shown in FIG. 2, the high-frequency current flowing out from one terminal of the piezoelectric element 16 that generates a high-frequency voltage, that is, the first intermediate electrode 17, flows between the first intermediate electrode 17 and the second intermediate electrode. The capacitance C1 formed between the electrode 19, the capacitance C2 formed between the intermediate electrode 19 of @2 and the container 1, and the earth potential including the container l and the current carrying path conductor 10. The current flows through the capacitance C, which is formed between the current-carrying path and the current-carrying path, and returns to the other terminal of the piezoelectric element 16. Therefore, the voltage generated between both terminals of the piezoelectric element 16 is divided by the ratio "C + "Gy '''Cs, where C is the static voltage over a long section of the current-carrying path including the current-carrying path conductor 10, as described above. Since it has a significantly larger capacitance than C+ + 02, C5 hardly shares the voltage, and for the high frequency voltage on the MHz order generated by the piezoelectric element, the current-carrying path is connected to the metal container, that is, the ground. They are at the same potential, so the first intermediate electrode 17 can be considered a conductor on the high potential side.

Therefore, the voltage of the piezoelectric element 16 is substantially divided from K only to C and C2. In this way, this voltage division method using capacitance is only possible by focusing on the fact that the normally energized path is not always at a high potential, but is at the same potential as the ground at high frequencies on the MHz order. This method makes it possible to prevent radio wave interference extremely effectively.

By the way, if the contact area of the contact part becomes smaller than the normal range due to changes in the contact pressure of the leaf spring, deformation or wear of the contact part, or defects during assembly, the current carrying capacity of the contact part will decrease. This may cause abnormal heat generation. On the other hand, since the magnitude of the vibration transmitted from the first piezoelectric element to the second piezoelectric element also differs depending on the contact area, the change in the current carrying capacity of the contact portion depends on the magnitude of the vibration transmitted to the second piezoelectric element, That is, the voltage generated by this piezoelectric element is detected by the voltage measuring means 20, and this voltage can be determined by comparing this voltage with the voltage when the contact portion is normal. Note that the energy transmitted from the first loop antenna to the second loop antenna necessary for this voltage detection, that is, the energy that causes mechanical vibration, can be small on the order of W (watts), so the high frequency power source 2 The high-frequency transmitting tube (magnetron in this embodiment) constituting the device can also be of an easily available size, making it possible to construct the poor contact detection device extremely easily.

〔Effect of the invention〕

As described above, according to the present invention, (1) Since the contact area of the contact portion can be quantitatively detected, it is possible to reliably determine whether the contact state is good or bad.

(2) The radio waves emitted from the first loop antenna are confined in a sealed container and are not emitted outside, so unlike X-rays, there is no radiation effect on the human body, making it easier to detect poor contacts. It can be done easily.

(3) Unlike the case of X-rays, high voltage generation is not required, so the power supply can be made smaller, and the energy transfer system can also be made smaller with only a loop antenna.
The entire contact failure detection device can be constructed compactly and economically, and can be easily incorporated into a constant monitoring system that comprehensively monitors the status of high-voltage electrical appliances.

(4) Since this device monitors the contact status of dormitory contact parts, danger can be predicted even in a non-current state.

Therefore, it can also be used to determine whether the assembled state of the contact portion is good or bad.

(5) Since the voltage generated in the second piezoelectric element is extracted by capacitance division, there is no influence of input radio waves on measurement results, and highly accurate detection is possible.

Effects such as this can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a poor contact detection device configured in a GiS cable connection section based on the present invention, and FIG.
The figure is an explanatory diagram of the principle of capacitance division with respect to the voltage generated in the second piezoelectric element. l...metal container, 2...high frequency power supply, 4...first
loop antenna, 6... current carrying path conductor, 7... first
piezoelectric element, 8... second loop antenna, 8a...
・Loop coil, 8b... Capacitor, 9a, 9
b... Contact portion, 10... Current-carrying path conductor, 16...
Second piezoelectric element, 17... First intermediate electrode, 19...
- Second intermediate electrode, 20...voltage measuring means. 1011 Raku 41 books 2nd figure

Claims (1)

[Claims] 1) A device for detecting poor contact of a connection part of a current-carrying conductor housed in a sealed metal container, comprising: a first loop antenna provided on the inner wall side of the metal container and powered from a high-frequency power source; A current-carrying path is connected to a second loop antenna, which is arranged opposite to the first loop antenna and is composed of a loop coil and a capacitor configured to be tuned to the frequency of the high-frequency power source, and which sandwiches the contact portion of the connection portion. a first piezoelectric element disposed on one side of the conductor; a second piezoelectric element disposed on the other side of the current-carrying path conductor sandwiching the contact portion and having one electric terminal connected to the current-carrying path conductor; a first intermediate electrode disposed between the metal container and the other electrical terminal of the second piezoelectric element, and a second intermediate electrode disposed between the first intermediate electrode and the metal container; A contact failure detection device for a current-carrying conductor connection portion, comprising: an intermediate electrode; and voltage measuring means for measuring a voltage between the second intermediate electrode and the metal container.