JPH02290571A - Detection of deterioration of arrester - Google Patents

Abstract

PURPOSE:To perform efficiently and accurately a grasp of deterioration and evaluation of heat stability by incorporating a crystal resonator with a zinc oxide element and arranging a temperature detecting device at the outside to detect the resonance frequency. CONSTITUTION:A crystal resonator sensor 15 consisting of an oscillator and a coupling coil is mounted on the zinc oxide element 12 and hermetically sealed in a insulator tube 13, and the temperature detecting device 16 detecting the resonance frequency is arranged in the outside position corresponding to the sensor 15. In the device 16, a high frequency made in the oscillation circuit 32 is applied to the crystal resonator with a probe coil 31, then the resonance frequency which is absorbed and unreflected by the resonator is detected with a resonance point detecting circuit 33 and converted to temperature data by a frequency/temperature conversion circuit 34 to detect a temperature of the element 12. With this arrangement, the temperature of element 12 impressed with a high voltage can be measured direct and accurately from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for detecting deterioration of a zinc oxide type lightning arrester, and particularly to a method for detecting deterioration using a crystal temperature sensor.

B. Summary of the Invention The present invention provides a method for detecting deterioration of a zinc oxide type lightning arrester, in which a crystal oscillator whose natural frequency changes depending on temperature is attached to a zinc oxide element, or is built into the arrester together with the zinc oxide element, and the oscillator is By installing a temperature detection device that detects the resonant frequency of the arrester in the outer part of the arrester, the temperature of the zinc oxide element to which high voltage is applied and which is hermetically sealed can be directly wirelessly measured from outside the arrester. The objective is to provide a technology that efficiently and accurately assesses deterioration and thermal stability.

C. BACKGROUND OF THE INVENTION It is known that the service life (life) of conventional zinc oxide type lightning arresters can usually be evaluated by thermal stability.

FIG. 9 is a curve diagram showing the heat balance characteristics of a zinc oxide type lightning arrester. In FIG. 9, the vertical axis indicates the amount of heat dissipated, and the horizontal axis indicates temperature change. Here, the heat radiation curve A is determined by the structure of the lightning arrester, and the heat generation curve B is determined by the characteristics of the zinc oxide element. In steady state,
The lightning arrester is at a temperature where the amount of heat dissipated and the amount of heat generated are balanced (stable point C)
However, as the zinc oxide element deteriorates, the heat generation curve B reaches its upper limit, and the stable point C' also rises. If the element temperature inside the surge arrester exceeds the heat radiation curve A due to deterioration or excessive surge absorption, the surge arrester will not be able to recover itself (self-recovery), leading to thermal runaway.

As is clear from the above description, understanding the temperature of the zinc oxide element is directly related to understanding the deterioration and evaluating the thermal stability of the zinc oxide type lightning arrester.

D. Problems to be Solved by the Invention Despite this, in the past, there have been few cases in which temperature measurement of zinc oxide elements has been applied to the deterioration diagnosis of zinc oxide type lightning arresters, and it has not been possible to measure power loss or resistance leakage current. It had been substituted. This is due to the following reasons.

(1) Since a high voltage is applied to the zinc oxide element, a high-voltage 41 constant device is required.

(2) In order to attach the temperature sensor to the zinc oxide element, it is necessary to draw out the lead wire from the sensor to the outside of the lightning arrester, but this may impair the airtightness, which is important for the lightning arrester.

The present invention was created in view of these problems, and
To provide a method for detecting deterioration of a lightning arrester, in which the temperature of a zinc oxide element to which a high voltage is applied is directly wirelessly measured from the outside of the arrester, and the deterioration of the arrester can be ascertained and the thermal stability evaluated efficiently and with high precision. The purpose is

E. Means for Solving the Problems Means for solving the above problems in the present invention are as follows: (1) In a method for detecting deterioration of a lightning arrester incorporating a zinc oxide element, a crystal resonator whose natural frequency changes depending on temperature is replaced with a zinc oxide element. (2) Oxidation In a method for detecting deterioration of a lightning arrester with a built-in zinc element, a crystal oscillator whose natural frequency changes depending on the temperature is attached to the zinc oxide element, or is built into the arrester together with the zinc oxide element, and the resonant frequency of the oscillator is detected. The present invention is based on a method for detecting deterioration of a lightning arrester in which a temperature detection device is provided outside the lightning arrester via an ultrasonic probe.

F. Effect (1) Crystal resonators generally have a Y-cut type AT cut offset from the Z axis by 35° to 15° because of their good stability in frequency/temperature characteristics, but are widely used for communication purposes. By slightly shifting the angle from the Z axis or by using the Y cut itself, a temperature sensor cord with good reproducibility of frequency/temperature characteristics can be obtained. Furthermore, if the frequency is set near IOM1-1z, which is easy to handle, a resolution of llz can be obtained. For example, if a cut angle of 80 pprn/' is selected, the resolution will be approximately 1/800°C. When high-frequency energy is externally applied to such a Y-cut type crystal unit, the natural vibration It has the property of absorbing high-frequency energy of the same frequency as the crystal oscillator, and the natural oscillation frequency of the crystal oscillator shows accurate temperature dependence. Therefore, a crystal oscillator that combines a oscillator and a coupling coil is used in the zinc oxide element part inside the lightning arrester. The temperature of the zinc oxide element can be measured by attaching a vibrator sensor and detecting the resonant frequency from the outside through electrical connection (electromagnetic coupling).This temperature detection device is installed in the outer part of the lightning arrester. By performing wireless measurements and monitoring temperature changes, it is possible to understand the deterioration of lightning arresters and evaluate their thermal stability.

(2) If the resonant frequency of the crystal is set to the ultrasonic vibration region of about 40 KHz, a crystal resonator sensor is attached to the zinc oxide element inside the lightning arrester, and acoustic cooperation from the outside (ultrasonic vibration coupling) is performed. By detecting the resonance frequency, the temperature of the zinc oxide element can be measured. In this case, the temperature detection device is arranged outside the lightning arrester via an ultrasonic probe. Therefore, even in a tank-type lightning arrester using a metal tank that shields electromagnetic waves, there is no need to draw out a lead wire from the sensor to the outside of the lightning arrester, and the airtightness of the lightning arrester is not hindered.

G. Embodiments Hereinafter, embodiments of the invention set forth in claim (1) will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing an example of an insulator type lightning arrester embodying the present invention. In the figure, a lightning arrester I1 is formed by sealingly housing a zinc oxide element 12 in a tube I3, and is connected to a bus bar I4. In this embodiment, the crystal resonator sensor l5 consisting of a resonator and a coupling coil is connected to the zinc oxide element l2.
A temperature detection device 16 for detecting the resonance frequency of the crystal oscillator is disposed outside at a position corresponding to the crystal oscillator sensor 15.

FIG. 2 is a configuration diagram showing an example of a tank type lightning arrester embodying the present invention. Tank-type lightning arresters are used for built-in transformers and insulating gas-filled equipment (GIS).As shown in the figure, the lightning arrester 2l is constructed by connecting a zinc oxide element 22 to a molded spacer 23 and attaching it to a tank. In this embodiment, a crystal resonator sensor 25 consisting of a resonator and a coupling coil is attached to the zinc oxide element 22 and then sealed. In this case, the electromagnetic waves are shielded by the metal tank 24 and do not reach the inside of the tank.
The probe coil 27 of the temperature detection device 26 is connected to the flange 2.
8, the resonant frequency of the crystal resonator is detected by placing it in the tank 24.

FIG. 3 is a configuration diagram of a temperature detection device used in the above embodiment. In the figure, 31 is a probe coil, 32 is an oscillation circuit, 33 is a resonance point detection circuit, 34 is a frequency/temperature conversion circuit, and 35 is a display circuit. In the same figure, the temperature detection device uses a high frequency generated by the oscillation circuit 32 as a probe.
A resonance point detection circuit 33 applies a resonance frequency that is applied to the crystal oscillator from the coil 31 and is absorbed by the crystal oscillator and not reflected.
The resonant frequency is detected by the frequency/temperature conversion circuit 34.
By converting it into temperature data, the temperature of the zinc oxide element is detected and output to the display circuit 35.

As already mentioned, the blow coil can be placed either outside or inside the arrester, but in any case there is no wiring connection to the crystal oscillator, and the temperature detection device is independent of the arrester. However, if the crystal oscillator sensor is built into the lightning arrester in advance, the temperature detection device itself can be transported freely and can be used with multiple lightning arresters. Further, if this temperature detection device is installed near the lightning arrester and its output is transmitted through a signal line or the like, it becomes easy to constantly monitor the deterioration of the lightning arrester.

FIG. 4 is an explanatory diagram showing an example of a crystal resonator sensor used in the above embodiment. As shown in Figure (a), the Y-cut type AT is generally shifted by 35° I5 from the Z axis.
However, in the embodiment of the present invention, a sensor is used in which a Y-cut type crystal shifted by 5 degrees to the positive side is housed in a metal cylinder with a diameter of 3xx and a height of Bxx. The resonance frequency is 10.6 MHz S l 6 70 Hz/°C, and the variation is ±0401°C. Figure 4(b) shows the axial direction of the crystal piece 3φX81 made by the cutting method shown in Figure (a).
! J! FIG. 2 is a diagram showing a rectangular plate crystal piece.

The relationship between the cut angle of the crystal and the frequency loss/temperature coefficient is as shown in FIG. In the figure, the horizontal axis shows the rotational cut angle around the X-axis, and the vertical axis shows the amount of frequency change per l. In the figure, the point where the frequency ZfjL degree characteristic curve first reaches a zero value is the AT cut angle, and the next point where the frequency ZfjL degree characteristic curve reaches a zero value is the BT cut angle. In Figure 5, the AT cut angle is 90°-
It is located at a point of 35 degrees, and the maximum sensitivity point (YS cut) is 90 (
0)", so it is best to select the cut angle of the sensor resonator near the ellipse in the figure. Even in that case, there will be linearity errors, so the computer Linearized through processing, 1/1000 to 1/
It is common to obtain a resolution of about 10,000°C with an error of ±3/100°C.

The embodiments of the present invention have the following effects.

(1) The temperature of a zinc oxide element to which a high voltage is applied can be measured directly and with high precision.

(2) Can be measured from outside the arrester. Temperature sensing devices only emit electromagnetic waves and detect the absorbed frequencies; they do not need to be connected to a sensor.

(3) Since it is wireless, there is no need to pull out the lead wire from the sensor to the outside of the lightning arrester, and it does not interfere with the airtightness of the lightning arrester.

(4) If the same sensor is built into each lightning arrester, multiple lightning arresters can be measured with one detection device.

Next, an embodiment of the invention according to claim (2) will be explained.

In FIG. 6, parts that are the same as those in FIG. 1 are indicated by the same reference numerals. In FIG. 6, the lightning arrester 1l includes a zinc oxide element 12! Formed by being sealed inside 3, the bus bar!
Connected to 4. In this embodiment, a crystal oscillator sensor l5 consisting of a vibrator and a coupled coil is attached to the zinc oxide element l2 and then sealed, and an ultrasonic probe 4! detects the resonance frequency of the crystal oscillator. and temperature detection device 36
Arrange the lightning arrester in the low voltage part of Uiro in summer.

FIG. 7 is a configuration diagram showing an example of a tank type lightning arrester implementing the invention of claim (2). In FIG. 7, the same parts as in FIG. 2 are designated by the same reference numerals. Tank-type lightning arresters are used for built-in transformers and insulating gas filled equipment (GIS).As shown in the figure, the lightning arrester 2l is installed inside a tank 24 by connecting a zinc oxide element 22 to a molded spacer 23. However, in this embodiment, a crystal oscillator sensor 25 consisting of an oscillator and a coupling coil is attached to the zinc oxide element 22 and then sealed.

In this case, in the electromagnetic wave coupling method described above, the electromagnetic waves are shielded by the metal tank 24, so it is necessary to install a detection probe inside the tank, but in the ultrasonic coupling method, the detection probe must be installed outside the tank as shown in Fig. 6. Ultrasonic probe 4
1 and a temperature detection device 36 may be installed.

FIG. 8 is a configuration diagram of the temperature detection device 36 used in the above embodiment. In the figure, 41 is an ultrasonic probe, 32 is an oscillation circuit, 33 is a resonance point detection circuit, 34 is a frequency/temperature conversion circuit, and 35 is a display circuit. In the figure, the temperature detection device applies a high frequency generated by an oscillation circuit 32 to a crystal oscillator from an ultrasonic probe 4I, and detects a resonance frequency that is absorbed by the crystal oscillator and not reflected by a resonance point detection circuit 33. The temperature of the zinc oxide element is detected by converting the resonant frequency into temperature data by the frequency/temperature conversion circuit 34 and output to the display circuit 35. In the embodiment described above, temperature measurement is performed by transmitting ultrasonic vibrations, so the ultrasonic probe 4l and temperature detection device 36 may be installed at a ground terminal outside the lightning arrester, a flange, a tube base, etc.

The embodiments of the present invention have the following effects.

(1) The temperature of a zinc oxide element to which a high voltage is applied can be measured directly and with high precision.

(2) Can be measured from outside the arrester. The temperature detection device only emits ultrasonic waves and detects the resonant frequency, and does not need to be connected to a sensor. In the case of tank-type arresters, measurements can also be made from the outside without lead wires.

(3) Since it is wireless, there is no need to pull out the lead wire from the sensor to the outside of the lightning arrester, and it does not interfere with the airtightness of the lightning arrester.

(4) If the same sensor is built into each lightning arrester! Multiple lightning arresters can be measured with one detection device.

H. Effects of the Invention As described above, according to the invention of claim (1), the temperature of the zinc oxide element to which high voltage is applied can be directly wirelessly measured from the outboard of the lightning arrester, and it is possible to understand the deterioration of the lightning arrester and to check its thermal stability. It is possible to provide a method for detecting deterioration of a lightning arrester that performs evaluation efficiently and with high accuracy.

Furthermore, according to the invention of claim (2), even when the zinc oxide element is housed in a metal tank like in a tank-type lightning arrester, the temperature of the zinc oxide element can be measured wirelessly directly from the outer part of the lightning arrester. In addition, it is possible to provide a method for detecting deterioration of a lightning arrester that efficiently and accurately assesses the deterioration of the lightning arrester and evaluates its thermal stability.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the invention of claim (1);
The figure is a configuration diagram of another embodiment of the invention as claimed in claim (1).
The figure is a configuration diagram of the temperature detection device of each embodiment of the invention of claim (1), Figure 4 is an explanatory diagram of the crystal resonator sensor, Figure 5 is a characteristic diagram of cut angle and temperature coefficient, and Figure 6 is A block diagram of one embodiment of the invention of claim (2), FIG. 7 is a block diagram of another embodiment of the invention of claim (2), and FIG. 8 shows each implementation of the invention of claim (2). FIG. 9, which is a configuration diagram of the example temperature detection device, is a characteristic diagram of the heat balance of the lightning arrester. 11.21...Lightning arrester, 12.22...Zinc oxide element, 15.25...Crystal oscillator sensor, 16,26.
36...Temperature detection device, 4l...Ultrasonic probe. Figure 1 is a diagram showing the configuration of an embodiment of the invention as claimed in claim (1). Figure 3 is a diagram showing the configuration of a temperature detection device. Explanatory diagram (b) Fig. 5 Characteristic diagram of cut angle and temperature coefficient Fig. 7 A structural diagram of an example of the invention of claim (2) Fig. 7 A structural diagram of another embodiment of the invention of claim (2) Figure 8 Configuration diagram of temperature detection device

Claims (2)

[Claims] (1) In a method for detecting deterioration of a lightning arrester with a built-in zinc oxide element, a crystal oscillator whose natural frequency changes with temperature is attached to the zinc oxide element, or it is built into the arrester together with the zinc oxide element, and the oscillator is A method for detecting deterioration of a lightning arrester, comprising disposing a temperature detection device for detecting a resonant frequency outside the lightning arrester. (2) In a method for detecting deterioration of a lightning arrester with a built-in zinc oxide element, a crystal oscillator whose natural frequency changes with temperature is attached to the zinc oxide element, or it is built into the arrester together with the zinc oxide element, and the oscillator is A method for detecting deterioration of a lightning arrester, comprising disposing a temperature detection device for detecting a resonance frequency outside the lightning arrester via an ultrasonic probe.