JPS63228082A - Method for diagnosing deterioration of zinc oxide type lightning arrester - Google Patents

Abstract

PURPOSE:To permit inexpensive and easy specification of a deteriorated phase by subjecting the currents flowing in respective phases to 3-phase vector synthesis and determining the composite waveform of only the resistance-component currents. CONSTITUTION:Only the lightning arresters 21, 22, 23 are connected to respective phases 11, 12, 13 of a bus or power transmission line and the ground sides thereof are commonly grounded via a zero phase current rectifier 44 as a piece of current detector. The ground side conductors of the respective phases of the lightning arresters 21, 22, 23 are collectively grounded through the iron core of a current transformer 44 and the secondary output of the transformer 44 is inputted to an amplifier 6, by which said output is amplified. The transformer 44 outputs the slight current of the specific phase on the primary side with good accuracy to the secondary side. The iron core thereof is saturated to prohibit outputting of the overcurrent to the secondary side at the time of large current. The currents passing the respective phases 11, 12, 13 are subjected to 3-phase vector analysis to erase the capacity- component currents contained in the currents of the respective phases and to determine the composite waveform of only the resistance-component currents. Whether the lightning having the deteriorated nonlinear resistance element exist in the 3-phase lightning arresters or not is diagnosed from this composite waveform.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides one or more serially connected
A non-linear resistance cord whose main component is zinc oxide is housed in a container, and a resistive current in the same phase as the terminal voltage of the arrester is passed through the arrester constituting each phase of the three-phase arrester. The present invention relates to a method for diagnosing deterioration of a zinc oxide lightning arrester, which diagnoses the presence or absence of deterioration of a linear resistance element.

[Conventional technology]

In a lightning arrester that consists of one or more non-linear resistance elements (hereinafter simply referred to as elements) containing zinc oxide as a main component housed in a container in series, due to the characteristics of the elements, it is difficult to resist under constant voltage application. The current that can flow is extremely small, usually several 10
The current is on the order of μ8, and because this level of current cannot cause a normal element temperature rise or element deterioration due to this temperature rise, the discharge gap in series with the nonlinear resistance element is usually omitted in practical use. Therefore, a small current always flows through the nonlinear resistance element.

However, depending on the operation and weather conditions (thermal cycles, etc.) that cause the abnormal voltage due to deformation, the element may deteriorate, and as this deterioration progresses, it will no longer be able to withstand the constant phase voltage in the grid. However, the elements may be destroyed and the system operation may be disrupted.Therefore, there is a need for a monitoring method that can constantly monitor the resistance current during operation to determine the initial state of deterioration.

In Figure 15, which shows the voltage-current characteristics of the element, actual M25 shows the characteristics when the element is in a normal state, and each point
1!35 shows the characteristics when the deterioration has progressed. Here, the current on the horizontal axis is the resistance that does not include the capacitive current based on the capacitance between both end faces of the element, which is usually formed in a disk shape. Let Vn be the phase voltage of the system, which shows only the divided current, and the current that flows through the elements under this voltage varies depending on the temperature of the element, but if the element is deteriorated, the current that flows even at the same temperature. For example, if the temperature of the element is 08, the current I□ that flows when the element is in a normal state is ! ,
changes greatly. Therefore, by measuring the resistance current that is constantly flowing and comparing it with the current of the element in a normal state, which corresponds to the temperature at the time of measurement, it is possible to accurately determine the presence or absence of deterioration. In addition, in the figure, the magnitude relationship of temperature θ is θ, >θ.

By the way, if you measure the current passing through the arrester with a current detector connected in series with the arrester, the voltage applied to the arrester is alternating current at the operating frequency, so the capacitance current will be added to the resistance current. It will be done.

FIG. 16 shows a surge arrester 2 whose upper and lower ends are connected to the line and the ground, respectively. If the container housing the element is an insulator, this arrester 2 shall include the insulator and the element. If it is a grounded metal, only the element is shown. FIG. 17 shows an electrical equivalent circuit of the lightning arrester shown in FIG. 16. Since the element is usually formed into a disk shape and forms a relatively large capacitance C between its two end faces,
The current that passes through the lightning arrester is the resistance current that causes the temperature of the element to rise ■Well, the capacitance current that passes through the capacitance! ,
In order to determine the deterioration of the element, it is necessary to extract only the resistance component current ■ from this vector sum. When the container is an insulator, the capacitance current l includes the capacitance current l, which has the capacitance of the insulator.

Figure 18 shows the conventional resistance current measurement method, and Figure 19 shows the conventional method for measuring resistance component current.
The figure shows voltage and current waveforms measured by the method shown in Figure 18. The lightning arrester 2 connected to the bus or power transmission line tIA1 is grounded via a current detector 4, and the bus or power transmission line is further connected to A voltage detector 3 is connected and the other end is grounded. Current detector 4. The outputs from the voltage detectors 3 are input to the arithmetic unit 8 via amplifiers 6 and 7, respectively.
The calculation of the resistance current is calculated based on the total current measured by the current detector 4, as shown in FIG. This is done by amplifying and subtracting the differential waveform of the voltage V measured by the voltage detector 3 from , so that the peak value matches the peak value shown in FIG. The resistance current Im thus obtained is compared with a normal resistance current at the element temperature measured in parallel with this measurement to determine whether there is any deterioration.

[Problem that the invention seeks to solve]

However, using this method, three
When attempting to perform automatic monitoring for diagnosing deterioration of lightning arresters for each phase, as shown in FIG. 20, current detectors 41, 42, .
43 and voltage detectors 31, 32, and 33, and has many switching contacts so that the current detection value and voltage detection value of the same phase can be respectively input to the amplifier 6.7. Requires container 5. It should be noted that since the progress of deterioration of an element is on the order of time at the fastest, the purpose can be sufficiently achieved by a method of making a determination while sequentially switching each phase.

As described above, diagnosing deterioration using the conventional method requires an increase in the number of power transmission lines, a large number of current detectors and wiring (although voltage detectors can be shared), and a large switching device that requires control for diagnosis. However, there was a need for a simple diagnostic method because of the drawback of increased complexity.

An object of the present invention is to provide a simple diagnostic method as an alternative to the conventional method, in which the number of current detectors and wiring increases as the number of power transmission lines to which lightning arresters are connected increases.

[Means for solving problems]

In order to achieve the above object, according to the present invention, one or more non-linear resistance elements connected in series and containing zinc oxide as a main component are housed in a container to form a three-phase lightning arrester. As a deterioration diagnosis method of diagnosing the presence or absence of deterioration of the non-linear resistance element using the resistance current in phase with the surge arrester terminal voltage passing through the surge arrester constituting each phase of the three-phase surge arrester, By performing three-phase vector synthesis of the currents passing through the three-phase surge arrester, the capacitance current that is added to each phase current is erased to obtain a composite waveform of only the resistance current, and from this composite waveform, the It is assumed that a diagnosis is made as to whether or not there is a lightning arrester whose linear resistance element has deteriorated.

[Effect]

First, the principle of the deterioration diagnosis method according to the present invention will be explained.

A measuring circuit for composing three-phase vectors of the currents passing through each phase of a three-phase lightning arrester is configured as shown in Figure 1, and the capacitance current that is combined with each phase current is erased to calculate the resistance current. The synthesized waveform of only 1 is obtained as shown in Fig. 2. Here, for example, a zero-phase current transformer is used as the current detector 44 in FIG.
．． 22. Each grounding conductor of 23 is collectively grounded through the current transformer iron core, and the secondary output of the current transformer is input to the amplifier 6 and amplified to obtain the composite waveform. .

In addition to the composite current waveform 420, FIG. 2 also additionally shows the arrester terminal voltage waveforms of each phase.

As can be seen from the current waveform in Figure 2, the waveform of this composite current is based on the voltage-current characteristics of the element, that is, the current increases rapidly when the applied voltage increases, and decreases rapidly when the applied voltage decreases. As shown in the figure, the waveform is a waveform containing many third harmonics, and the position of its peak value coincides with the position of the peak value of the voltage waveform. Therefore, if deterioration occurs in the elements of any phase of the three-phase lightning arrester, the current peak value of that phase will be greater than the current peak value of the remaining phases that appears every 60 degrees of electrical angle following this peak value. becomes large, and it is diagnosed that the element of that phase has deteriorated. However, since what is measured by the measurement circuit in Figure 1 is only the composite current waveform, it is not possible to identify the phase in which the element is deteriorating from this waveform alone.
In a three-phase surge arrester, where three phases of the surge arrester are housed in a common container, even if the element in any phase deteriorates, the metal phase will be replaced with a new one, and the upgrade will be completed within a short period of time. In the case of such a three-phase lightning arrester, the present invention provides a method of diagnosing deterioration that is much simpler than the conventional method. In addition, in a three-phase lightning arrester where the elements of each phase are housed in independent insulator tubes and installed outdoors, only the phase in which the element has deteriorated is replaced, but in this case as well, this will be explained in detail in the following example. As explained, the current passing through the arrester was combined into three-phase vectors. By using a composite waveform of only the resistance current, it becomes possible to identify the deteriorated phase at low cost.

〔Example〕

FIG. 1 shows an example of a circuit configuration that enables the deterioration diagnosis method of the present invention, and shows each phase 11.1 of a bus bar or power transmission line.
Only lightning arresters 21, 22, and 23 are connected to 2.13,
The ground side thereof is commonly grounded via one current detector. In this embodiment, a zero-phase current transformer is used for this current detector, and the grounding side conductors of each phase of the lightning arrester are collectively grounded through the current transformer iron core, and the secondary side output of the current transformer is grounded. is input to the amplifier 6 and amplified. This zero-phase current transformer has the characteristic of accurately outputting a small current of a specific phase on the primary side to the secondary side, and also prevents the iron core from saturating when the current is large and excessive voltage is not output to the secondary side. It has characteristics suitable for diagnosing deterioration of lightning arresters.

Note that a broken line 80 represents a common metal container that accommodates elements for three phases.

FIG. 2 shows a current waveform obtained from the output side of the amplifier 6 using the circuit configuration shown in FIG. 1, and a three-phase voltage waveform that generates this current waveform, superimposed on each other.

Here, 111, 112, 113 respectively indicate the ground voltage of each phase of the bus or transmission line, and 421, 422, 4
23 indicates a peak value that appears every 60 electrical angles in a composite current waveform 420 obtained by vector-synthesizing the currents flowing through each phase arrester. In addition, the waveform of this composite current is the voltage-current characteristic of the element, that is, the current increases rapidly when the applied voltage increases, and decreases rapidly when the applied voltage decreases. It takes a waveform that contains many harmonics, and the position of its peak value is completely different from the position of the peak value of the voltage waveform. Therefore, if deterioration occurs in the elements of any phase of the three-phase lightning arrester, the current peak value of that phase will be greater than the current peak value of the remaining phases that appears every 60 electrical degrees following this peak value. becomes large, and it is diagnosed that the element of that phase has deteriorated.

Note that the deterioration diagnosis method of the present invention does not measure the voltage waveform of each phase, so it is not possible to specify which phase deterioration occurs in. However, as mentioned above, this is especially true for three-phase lightning arresters. In consideration of the practice of maintenance work, where all three phases are housed in a common metal container, even if any phase has deteriorated, all three phases are replaced with new ones and the renewal is completed as soon as possible.
The conventional voltage detector is omitted to simplify the circuit configuration for diagnosis.

Fig. 3 shows a circuit configuration for deterioration diagnosis according to a second embodiment of the present invention. Figure 2 shows an example of a circuit configuration that makes it possible to identify the deteriorated phase so that only the surge arrester of the phase in which the element has deteriorated can be updated. As shown in the figure, this is easily possible by simultaneously recording the relative ground pressure of each bus bar and transmission line, and the voltage detector for this recording is a three-phase surge arrester common to all three-phase lightning arresters. It can be used as one set per minute and does not require multiple sets like current detectors. However, voltage detectors connected to high voltage lines are expensive.
It is desirable to have an identification method that can minimize the number of items.

Lightning arresters 2 are installed on each phase 11, 12, 13 of the bus or transmission line.
1, 22, and 23 are connected, and their ground sides are installed in common through one current detector 44, and a voltage detector 3 is connected to one phase of the bus or power transmission line, phase 11 in this case. It is connected. Note that the current detector 44 includes:
Similar to the one in FIG. 1, a zero-phase current transformer is used that has characteristics suitable for diagnosing deterioration of a lightning arrester.

The current detected by the current detector 44 and amplified by the amplifier 46 is input to the calculator 47, and the input current value is a value equivalent to a preset reference level, that is, a value large enough to prove initial deterioration of the lightning arrester element. A pulse voltage is generated when the value corresponding to the level set as (the reference level shown in FIG. 4) is exceeded, and this pulse voltage is input to the calculator 49. On the other hand, the waveform of the bus line or phase voltage measured by the voltage detector 3 is input to the calculator 48, which generates a pulse voltage at the peak position of the input voltage waveform, and inputs this pulse voltage to the calculator 49. do.

The arithmetic unit 49 calculates the time difference between the pulse voltage generated at the peak position of this voltage waveform and the pulse voltage generated when the magnitude of the composite current exceeds the reference level.
Identify the deterioration tank using the diagram. That is, as shown in Fig. 5, the busbar or transmission ti phase to which the voltage detector is connected is set as the R phase, and the pulse voltage generated at the ground voltage peak position of the R phase is used as the reference pulse that forms the origin of time measurement. Measure the time until the pulse voltage generated when the magnitude of the composite current exceeds the reference level. If this time is almost zero, the deterioration tank is in the same phase as the reference phase, and if it is equivalent to 1200 electrical angles, the phase is in sequence. Accordingly, if the next phase corresponds to an electrical angle of 240'', the deterioration tank can be identified as the next phase at low cost and easily.

FIG. 6 shows a circuit configuration for deterioration diagnosis according to a third embodiment of the present invention. This embodiment is similar to the second embodiment.
This shows the circuit configuration for identifying the deterioration tank, and it shows the circuit configuration for identifying the deterioration tank.
transformer) or partial pressure Vt, so-called P
A superimposed current generator 55, which will be described in detail below, is connected to the secondary side of the D (potential device) 50 via a switch 54, and a zero-phase current transformer, which is a current detector, is connected to the output side of this generator. An output conductor 55a passing through the 44 iron cores is connected.

The superimposed current generator 55 generates a non-linear current that degrades the current passing through the arrester under the ground voltage of the busbar or transmission line until it reaches a current level set as being large enough to demonstrate initial degradation of the arrester element. When the secondary voltage of the PT or PD 50 is introduced via the switch 54, the current waveform obtained when the ground voltage is applied to the resistive element is reversed in synchronization with the secondary voltage. The circuit configuration is such that the waveform of the three-phase vector composite current obtained on the secondary side of the zero-phase current transformer 44 in the circuit state of the switch 54 is output to each phase of the switch 54. The aim is to identify the phase surge arrester in which the element has deteriorated based on how it changes when the elements are alternately closed. That is, as shown in FIG.
This is obtained when all three phases of the arrester element are healthy in the open circuit state. If the waveform deforms into a composite waveform of only the resistance current (al is the peak of the waveform) and its maximum peak value exceeds a preset deterioration level, an alarm will be issued via an alarm circuit not shown in Figure 6. It is notified that at least one phase of the lightning arrester has deteriorated. When the switch 54 is closed manually or automatically, the PT or PD5
The phase voltages of each phase obtained on the secondary side of 0 are taken into the superimposed current generator 55 so as to have opposite polarities, and a current having the same waveform as the current at the deterioration level in waveform ('b) is generated. is output with reverse polarity.

Therefore, when the R phase of the switch 54 is closed, if a waveform is obtained on the secondary side of the zero-phase current transformer 44 (as shown in cl) in which the current waveform at the deterioration level disappears, the deterioration of the lightning arrester is It turns out that this has occurred at least in the R phase.Next, if a waveform like fd+ is obtained when the R phase of the switch 54 is opened and the T phase is closed, in this case, the current waveform at the deterioration level disappears. This shows that the T-phase lightning arrester element has not deteriorated.Similarly, switch 5
Even when only the S phase of No. 4 is closed, the current waveform at a degraded level like the waveform fa+ does not disappear, so the degraded tank can be identified as the R phase by the above switch operation.

FIG. 3 shows how the composite current waveform changes during the diagnosis process when element deterioration occurs in two phases of a lightning arrester. For example, the R and S phases of the switch 54 are closed due to the activation of an alarm device (not shown). When the waveform of the composite current is shown in the same figure (b
Suppose that the current waveform changes as shown in FIG. 1 and the two-phase current waveform at the deterioration level disappears. Next, when the S phase and T phase of the switch are closed, as shown in the same figure (c), the current at the deterioration level in one phase does not change, and the current at the deterioration level in the phase adjacent to this phase does not change. It is assumed that a current waveform with a difference from a healthy resistance current appears, and the current waveforms of the remaining l phases disappear. Furthermore, when the T and R phases of the switch are closed, the current waveform of one phase disappears, and the current waveform of the difference between the deterioration level current and the healthy resistance current appears in the adjacent phase. , it is assumed that the current waveform of the remaining one phase at the deterioration level remains unchanged. Although the switch may be operated in any manner, it is possible to identify the degraded phases as the R phase and the S phase from the change in the waveform of the combined current when two phases are operated in this manner.

FIG. 9 shows a circuit configuration for deterioration diagnosis according to a fourth embodiment of the present invention, a lightning arrester 2 constituting each phase of a three-phase lightning arrester.
A current detector for obtaining a three-phase vector composite waveform of the current passing through 1.22.23, in this case a lightning arrester that passes through the annular core of the zero-phase current transformer 4. The grounding side conductor of each phase of the lightning arrester is equipped with a switch 61a, Bypass circuits 61, 62, and 63 spanning the zero-phase current transformer 4 are connected via 62a and 63a, and by closing these switches, a portion of the current passing through the arrester passes through the zero-phase current transformer. (The current is shunted to the bypass circuit.The ratio of the current to the bypass circuit is such that the current transformation ratio of the zero-phase current transformer is too +, and the current is shunted to the bypass circuit. Since the impedance of the current transformer is almost negligible, it is thought that the impedance will be about 50% if the conductor of the bypass circuit has the same cross-sectional area as the primary conductor of the current transformer. An example of the passing current waveform of each phase of the lightning arrester when all 62a and 63a are open is shown.
FIG. 1 shows a three-phase vector composite waveform of the passing currents of each phase shown in FIG. 10, that is, a composite waveform of only the resistance current. As seen in this waveform example, when element deterioration occurs in the R-phase lightning arrester, the bypass circuit switches 61a and 62
9 which shows the current waveform obtained on the secondary side of the current transformer when the switches 63a and 63a are alternately closed. Similarly, the symbol R+S/2+T indicates the current waveform obtained on the secondary side of the current transformer when the switch 62a is closed, and the symbol R+S+T/2
shows the current waveform when the switch 63a is closed.

As seen in FIG. 12, the maximum peak value of the combined current when the switch 61a is closed is reduced below the deterioration level, that is, the set level, which is set in advance to be large enough to prove the initial deterioration of the element, and the switch 61a is When the switch 62a is closed, it does not change, and when the switch 63a is closed, it is reduced to below the set level again.

A method for identifying the phase surge arrester whose element has deteriorated based on changes in the current waveform caused by such switch operations will be described in detail after a modification of the first embodiment described below.

FIG. 13 shows a modification of the embodiment shown in FIG. 4.

In this modification, when the switches 61a, 62a, and 63a are closed, the proportion of the current diverted to the bypass circuits 61, 62, and 63 is reduced from about 50% in the fourth embodiment to the actual 1i10%.
The circuit configuration is designed to make it 0%, and the grounding side conductor of each phase of the lightning arrester has a low impedance 71.72.73.
are inserted in series, respectively, and the switches 61a and 62a
, 63a are the zero-phase current transformer 44 and the low impedance 71.
A bypass circuit 6L straddling 62 and 73 is inserted in series with 62 and 63. Here, low impedance 71.
72. The impedance of 73 shall be small enough not to increase the ground voltage appearing at the bus bar or transmission line side terminal to a value that threatens the insulation of the bus bar or transmission line when the arrester operates in response to a lightning strike. shall be.

In such a circuit configuration, if element deterioration occurs in the R-phase lightning arrester 21, and if the maximum peak value of the composite current waveform obtained on the secondary side of the zero-phase current transformer 44 exceeds the set level, The computing unit 45 determines this excess and sends a control signal to the switch control device 75, and switches 61a, 62
a and 63a are alternately and repeatedly opened and closed at appropriate time intervals. In Figure 14, which shows the state of change in the composite current waveform at this time, for example, the symbol SAT indicates the case where the current on the primary side of the current transformer is only the passing current of the S-phase lightning arrester and the T-phase lightning arrester, that is, the switch 61a. When the switch 62a is closed, the current waveform obtained on the secondary side of the current transformer is shown when the entire passing current of the R-phase lightning arrester is commutated to the bypass circuit 61.Similarly, when the switch 62a is closed, Also, the sign R+
S indicates a waveform of 1 when the switch 63a is closed.

As shown in FIG. 14, when the switches 61a and 63a are closed, the combined current maximum peak value is reduced to a preset deterioration level, that is, below the set level, and when the switch 62a is closed, it does not change.

From the above, from FIGS. 12 and 14, the relationship between the switch operation and the state of change in the maximum peak value of the combined current is shown in the table below.

That is, it can be seen that the combined current maximum peak value does not change only when the switch belonging to the phase next to the phase in which the element has deteriorated is closed. Therefore, if the switches are alternately closed and no change in the maximum peak value of the combined current occurs when the switch of a certain phase is operated, the lightning arrester of the phase that precedes the phase to which that switch belongs can be identified as a degraded phase. .

〔Effect of the invention〕

As described above, according to the present invention, each of the three-phase lightning arresters includes one or more non-linear resistance elements connected in series and containing zinc oxide as a main component in a container. As a deterioration diagnosis method of diagnosing the presence or absence of deterioration of the non-linear resistance element using a resistor current having the same phase as the terminal voltage of the surge arrester, which passes through the surge arrester constituting the phase, By performing three-phase vector synthesis of the currents, the capacitance current that is combined in each phase current is erased, and a composite waveform of only the resistance current is obtained. From this composite waveform, the nonlinear resistance in the three-phase arrester is calculated. Since it is now possible to diagnose whether or not there is a surge arrester with deteriorated elements, the number of current detectors and wiring required for deterioration diagnosis is reduced compared to conventional methods, even if there are many surge arresters that are subject to deterioration diagnosis. The three-phase vector obtained by the method of the present invention can be used not only in the case of three-phase lightning arresters that do not require identification of degraded phases, but also in the case of three-phase lightning arresters that require identification of degraded phases. By using the composite current waveform, it is possible to easily specify the degraded phase at low cost.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram for diagnosing deterioration of a lightning arrester element according to the first embodiment of the present invention, and FIG. 2 is a composite current waveform of a three-phase lightning arrester obtained by the circuit configuration of FIG. FIG. 3 is a waveform diagram showing the respective relative ground torturous pressure waveforms of the connecting bus or power transmission line superimposed on this composite current waveform. FIG. 3 is a circuit configuration diagram for diagnosing deterioration of a lightning arrester element according to the second embodiment of the present invention. The figure shows the voltage obtained with the circuit configuration shown in Figure 3. A waveform diagram showing the mutual time relationship of the current, these voltages, and the pulse voltage obtained from the current. Figure 5 is a pulse voltage waveform diagram for identifying the deterioration phase. Figure 6 is the third waveform diagram of the present invention.
A circuit configuration diagram for diagnosing deterioration of a lightning arrester element according to an embodiment of the present invention, and FIG. 7 is a waveform showing changes in the three-phase vector composite current waveform during the diagnosis process to identify the phase when an element of one phase of the arrester has deteriorated. Figure 8 is a waveform diagram showing how the three-phase vector composite current waveform changes during the diagnostic process to identify the two phases when the elements of the two phases of the lightning arrester have deteriorated. A circuit configuration diagram for diagnosing deterioration of a lightning arrester element according to an embodiment. FIG. 10 is a waveform diagram showing the passing current waveform of each phase of the arrester when the element of one phase of the arrester has deteriorated. FIG. Figure 12 is a waveform diagram showing the three-phase vector composite current waveform of the 1i current passing through each phase. FIG. 9 is a circuit configuration diagram for diagnosing deterioration of a lightning arrester element according to a modification of the fourth embodiment, and FIG. 14 is a waveform diagram showing a two-phase vector composite current waveform excluding all of the surge arrester passing current of any one phase. ,
Figure 15 is a line diagram showing the difference between the normal characteristics of a lightning arrester element and its deteriorated characteristics, Figure 16 is a single line diagram showing the connection status of the arrester with an external circuit, and Figure 17 is the current passing through the arrester. Equivalent circuit diagram of a lightning arrester, showing the current components in the 18th
The figure shows an example of a conventional measurement circuit diagram configured for one phase of a surge arrester in order to extract only the resistance current of the current that encounters the arrester. FIG. 20 is a current waveform diagram showing the waveforms of current components in the current, and is an example of a conventional measurement circuit diagram for a royal power surge arrester for extracting only the resistance current of the current passing through the surge arrester. 2) 21.22.23: Lightning arrester, 3, 31.32.3
3: Voltage detector, 4.41.42.43.44: Current detector, 50: Voltage transformer (PT) or voltage divider (
PD), 54: Switch, 55: Superimposed current generator, 61
．． 62.63: Bypass circuit, 61a, 62a, 6
3a: Switch, 420: Three-phase vector composite current waveform. Figure 1 Figure 3 Figure 13 Figure 16 Figure 17 Tower 18 Figure

Claims (1)

[Claims] 1) A lightning arrester that constitutes each phase of a three-phase lightning arrester, in which one or a plurality of non-linear resistance elements mainly composed of zinc oxide are housed in a container and are connected in series. In a deterioration diagnosis method for diagnosing the presence or absence of deterioration of the non-linear resistance element using a resistor current that is in phase with the lightning arrester terminal voltage,
By performing three-phase vector synthesis of the currents passing through each phase of the three-phase lightning arrester, the capacitance current that is combined in each phase current is eliminated to obtain a composite waveform of only the resistance current, and this composite waveform is A method for diagnosing deterioration of a zinc oxide type lightning arrester, comprising diagnosing whether or not there is a three-phase lightning arrester in which a nonlinear resistance element has deteriorated. 2) In the method described in claim 1, the three-phase vector composition of the currents passing through each phase of the three-phase lightning arrester is:
1. A method for diagnosing deterioration of a zinc oxide lightning arrester, characterized in that the method is carried out using a through-type current transformer having an annular core through which three-phase conductors on the primary side are passed all at once. 3) In the method described in claim 1, when the maximum peak value of the composite waveform of only the resistance current exceeds a predetermined value, a pulse voltage is generated and one of the three phases is generated.
Deterioration of a zinc oxide type surge arrester, characterized in that a pulse voltage is generated at a predetermined position of a phase surge arrester terminal voltage waveform, and a phase surge arrester having a deteriorated non-linear resistance element is identified from the time difference between the two pulse voltage generation points. Diagnostic method. 4) In the method described in claim 1, when the maximum peak value of the composite waveform of only the resistance current exceeds a predetermined value, the nonlinear resistance element that has been degraded in advance to this predetermined value and each A current waveform having the same peak value as the predetermined value obtained by combining the surge arrester terminal voltage of the phase is sequentially superimposed on the composite waveform with opposite polarity for each phase, and waveforms near the portion exceeding the predetermined value are erased. 1. A method for diagnosing deterioration of a zinc oxide type lightning arrester, the method comprising identifying a phase arrester having a deteriorated non-linear resistance element. 5) In the method set forth in claim 1, when the maximum peak value of the composite waveform of only the resistance current exceeds a predetermined value, part or all of the current that sequentially passes through any one phase lightning arrester. The deterioration of a zinc oxide type lightning arrester is characterized by vector-synthesizing the three-phase or two-phase currents excluding the above, and identifying the phase arrester having a deteriorated nonlinear resistance element from a comparison of the combined waveforms. Diagnostic method.