JP4554447B2 - Ion movement recognition method - Google Patents

Description

  The present invention, for example, for a lightning arrester composed of a current limiting element mainly composed of zinc oxide, moves ions inside the current limiting element based on the change in leakage current that appears due to the degree of deterioration over time. The present invention relates to a method of recognizing ion movement for grasping the situation.

  For example, lightning arresters installed in substations, etc., protect the peripheral equipment from surges when abnormal voltages occur due to lightning surges caused by lightning strikes or switching surges caused by turning on / off switches, breakers, etc. .

  This lightning arrester includes a plurality of current limiting elements mainly composed of zinc oxide (ZnO) having non-linear current-voltage characteristics that exhibit low resistance to surge voltage and high resistance to normal ground voltage. The laminated body has a structure in which an insulating outer body such as an elastic polymer or EPDM is attached to the outer peripheral surface of the laminated body.

  When an abnormal voltage occurs due to lightning surge or switching surge, surge current flows to the ground via the current limiting element. At this time, the current limiting element has a low resistance value with respect to the abnormal voltage and immediately escapes to the ground. If the abnormal voltage disappears, the current limiting element has a high resistance value and cuts off the normal ground voltage. To do. This valve action protects the peripheral equipment of the lightning arrestor installed in the substation.

  This lightning arrester has the property that the resistance leakage current once decreases at the initial stage of power application and increases with the lapse of the power application time. The reason why the resistance leakage current decreases in the initial stage of the voltage application is that oxygen ions existing inside the current limiting element are diffused during the voltage application and released to the outside. The oxygen ions are absorbed from the outside into the current limiting element during no electric charge. As the oxygen ions diffuse and are released to the outside, the resistance leakage current decreases exponentially with the application time. On the other hand, the reason why the resistance leakage current increases with the lapse of the charging time is that zinc ions inside the current limiting element diffuse in proportion to the concentration gradient. As the zinc ions diffuse, the resistance leakage current increases in proportion to the square root of the charging time along with the charging time.

  As described above, in this lightning arrester, in the initial stage of voltage application, oxygen ions existing inside the current limiting element diffuse and are released to the outside, so that the resistance leakage current once decreases exponentially, As time elapses, zinc ions inside the current limiting element diffuse in proportion to the concentration gradient, so that the resistance leakage current increases in proportion to the square root of the charging time.

  In this way, oxygen ions and zinc ions move during current application inside the current limiting element, but in order to grasp the state of this ion movement, the composition of the material of the current limiting element has conventionally been changed using an electron microscope or the like. There has been a means of observing or analyzing a reflected signal from a material by an X-ray analyzer or the like to observe a composition change.

  However, in order to grasp the state of ion movement inside the current limiting element, an expensive electron microscope or X-ray analyzer must be used, and specialized analysis techniques are required. In addition, it is difficult to grasp the state of ion movement inside the current limiting element in the no-voltage state.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to provide an element in an uncharged state by a simple means without using an expensive electron microscope or X-ray analyzer. An object of the present invention is to provide a method of recognizing ion movement that can grasp the state of ion movement inside.

  As a technical means for achieving the above-described object, the present invention is directed to an element in which a predetermined current as a characteristic parameter changes over time due to deterioration while the element temperature is kept constant. By repeating the non-electricity and non-electricity while changing the non-electricity time, and measuring the change of the predetermined current flowing through the element during the electric power application, It is characterized by grasping the state of ion movement inside the element when no power is applied based on the change.

  Here, as the element, for example, a current limiting element mainly composed of zinc oxide is applicable, and a lightning arrester constituted by the current limiting element is used as an object for grasping the ion movement state. When using the current limiting element of the lightning arrester, a predetermined current as a characteristic parameter may be used as a resistance leakage current. Since this resistance leakage current becomes total leakage current by adding capacitance leakage current, since this total leakage current is proportional to the resistance leakage current, the total leakage current is used as a characteristic parameter instead of the resistance leakage current. It is also possible to set a predetermined current. In addition, in the lightning arrester called the first generation, the resistance leakage current has a characteristic that increases with the charging time, but in the lightning arrester called the second generation, the characteristic that the resistance leakage current attenuates with the charging time. Have The present invention can be applied to any first generation or second generation lightning arrester.

  When the present invention is applied to a lightning arrester equipped with a current limiting element, first, the current limiting element temperature is kept constant by installing the current limiting element in a thermostat having a high hermeticity. In this state, power application to the current limiting element and no power application are repeated. In other words, when a predetermined voltage is applied to the current limiting element, the inside of the element that is in an equilibrium state with no voltage applied becomes unbalanced and ion migration occurs inside the element, and then the voltage to the current limiting element When the application is stopped, ions inside the device try to return to the original equilibrium state.

  In this way, when repeating the application of current to the current limiting element and the application of no power to the current limiting element, the resistance leakage current flowing through the current limiting element changes when the power is applied by changing the non-application time. By measuring this resistance leakage current, based on the change in resistance leakage current that appears due to the difference in each no-charge time, it is possible to understand under what circumstances ion migration occurs during no charge. be able to. In addition, about the ion movement at the time of charging, it is possible to grasp | ascertain directly from the increase / decrease in the resistance leakage current at the time of the charging.

  The present invention can be applied not only to the current limiting element constituting the lightning arrester as described above, but also to a diode which is an electronic component. In this case, a predetermined current as a characteristic parameter may be a reverse current.

  According to the present invention, with respect to an element in which a predetermined current as a characteristic parameter changes with time due to deterioration, in the state where the element temperature is kept constant, the electric power is applied to the element and the electric power is not applied to the electric power. By measuring the change in the predetermined current that flows through the element when the power is applied, based on the change in the predetermined current that appears due to the difference in each non-electricity time. Because it is possible to grasp the state of ion movement in the device without using an expensive electron microscope or X-ray analyzer, it is possible to grasp the state of ion movement inside the device in an uncharged state by using simple means. Is big.

  An embodiment of the present invention will be described in detail. In the following embodiments, a current limiting element mainly composed of zinc oxide is applied as an element whose predetermined current as a characteristic parameter changes over time, and a lightning arrester configured by the current limiting element is ion-transferred. It is an object for grasping the situation. In this case, a predetermined current as a characteristic parameter is set as a resistance leakage current. Further, in this embodiment, a lightning arrester (first generation) composed of a current limiting element in which the resistance leakage current increases with the application time is targeted.

  As shown in FIG. 1A, the lightning arrester 1 used in this embodiment is an oxidation having a non-linear current-voltage characteristic showing a low resistance against a surge voltage and a high resistance against a normal ground voltage. A plurality of current limiting elements 2 mainly composed of zinc (ZnO) are laminated, and the outer peripheral surface of the laminated body (see FIG. 5B) is covered with an insulating outer covering 3 such as an elastic polymer or EPDM. Has the structure.

  In the lightning arrester 1, when an abnormal voltage is generated due to a lightning surge or an opening / closing surge, a surge current flows to the ground through the current limiting element 2. At this time, if the current limiting element 2 has a low resistance value with respect to the abnormal voltage and immediately escapes to the ground, and the abnormal voltage disappears, the current limiting element 2 becomes a high resistance value and the normal ground voltage Shut off. This valve action protects the peripheral equipment of the lightning arrester 1 installed in the substation.

  As shown in FIG. 2, by installing the current limiting element 2 of the lightning arrester 1 in a thermostat 4 having a high sealing property, the current limiting element temperature is kept constant (for example, 65 ° C.). In this state, the application of electric power to the current limiting element 2 and no electric power are repeated by the accelerated life test. In this accelerated life test, a voltage of, for example, 3 kV is applied to the current limiting element 2 installed in the thermostatic chamber 4 from the AC constant voltage source 7 in the voltage applying device 6 via the electrodes 5 attached to both ends thereof. The resistance leakage current generated during the application of voltage to the element 2 is measured by the measuring instrument 8 in the voltage applying device 6.

FIG. 3 shows the characteristics of the resistance leakage current that flows through the current limiting element 2 by repeating the application of current to the current limiting element 2 and the non-application of current. In FIG. 3, the horizontal axis is time t, the vertical axis is resistance leakage current ir, and the no-charge time t _r1 , _{tr 2} , _tr 3 has a time width in practice, but the resistance leakage current ir does not flow. Therefore, for convenience, it is shown in a state where there is no time width. In addition, at the end of power application, that is, immediately before the start of no power application, the resistance leakage current ir _p is kept constant, and power application and no power application are repeated.

  When a predetermined voltage is applied to the current limiting element 2 in the thermostatic chamber 4 by the AC constant voltage source 7 of the voltage applying device 6 in the repetition of the voltage application to the current limiting element 2 and no voltage application, no equilibrium is applied to the current limiting element 2. When the voltage applied to the current limiting element 2 is stopped, the ions inside the element will return to the original equilibrium state. To do. That is, as shown in FIG. 3, the resistance leakage current ir once decreases at the initial stage of power application, and increases as the power application time t elapses.

Here, FIG. 4 is a schematic diagram of the potential barrier inside the current limiting element during power application, and FIG. 5 is a schematic diagram of the potential barrier inside the current limiting element during no voltage application. The inside of the current limiting element is composed of a grain boundary layer made of ZnO particles serving as a depletion layer and Bi ₂ O ₃ .

In the initial stage of voltage application, the resistance leakage current ir decreases because, as shown in FIG. 4, oxygen ions existing inside the current limiting element 2 diffuse and are forced to the outside along the interface of the grain boundary layer. This is because it is released. Oxygen ions are absorbed into the current limiting element 2 from the outside during no charge (see FIG. 5). The oxygen ions are released or absorbed while the reaction rate is proportional to the concentration. As described above, the oxygen ions are diffused and released to the outside during the voltage application, so that the resistance leakage current ir decreases exponentially with the voltage application time t. In other words, the resistance leakage current ir due to the diffusion and release of oxygen ions is assumed to have an initial value of ir _dn and a charging time t of ir = ir _dn · e ^−H · ^t (H Decreases with the power application time t so as to satisfy the coefficient n = 0, 1, 2,.

On the other hand, the reason why the resistance leakage current ir increases with the lapse of the charging time t is that zinc ions inside the current limiting element are forcibly diffused toward the interface of the grain boundary layer as shown in FIG. In addition, zinc ion diffuses in the direction opposite to the interface direction of the grain boundary layer and returns to the original state during no charge. As described above, the zinc ions diffuse in the interface direction of the grain boundary layer during voltage application, so that the resistance leakage current ir increases in proportion to the square root of the voltage application time t together with the voltage application time t. In other words, the resistance leakage current ir due to the diffusion of zinc ions has an initial value of ir _0n , and the charging time is t. The resistance leakage current ir is expressed by a relational expression of ir = ir _0n (1 + h√t) ( h increases with the application time t so as to satisfy the coefficient, n = 0, 1, 2,.

In this way, the repeated voltage application and no voltage application to the current limiting element 2, by varying the non-voltage application time _{t r1, t r2, t r3} , resistance leakage current flowing when the voltage application to the current limiting element 2 ir changes. By measuring this resistance leakage current ir with the measuring instrument 8 in the power application device 6, based on the change in the resistance leakage current ir that appears due to the difference of the non-electricity-applying times _tr1 , _tr2 , and _tr3. It is possible to grasp the situation in which ion migration occurs when no power is applied.

That is, it shows an ion moving situation in suck conductive time based on the resistance leakage current ir _01, ir _02, ir ₀₃ each unsubstituted Division charging time t _r1, t _r2, t _r3 is changed by different in FIG. In Figure 6, the horizontal axis represents the square root of the non-voltage application time t _r, the vertical axis represents the resistance leakage current ir. As shown in FIG. 6, the resistance leakage currents ir ₀₁ , ir ₀₂ , ir ₀₃ tend to decrease, and in this case, grasp the situation where zinc ions diffuse inside the current limiting element 2 and return to the original state. Can do.

Also, shows an ion moving situation in suck conductive time based on the resistance leakage current ir _d1, ir _d2, ir _d3 of each non-Division charging time t _r1, t _r2, t _r3 is changed by different in FIG. In FIG. 7, the horizontal axis is the no-charge time _tr , and the vertical axis is the resistance leakage current ir. As shown in FIG. 7, the resistance leakage currents ir _d1 , ir _d2 , ir _d3 tend to increase, and in this case, it is possible to grasp the situation in which oxygen ions are absorbed from the outside of the current limiting element 2 to the inside.

The above-described resistance leakage currents ir ₀₁ , ir ₀₂ , ir ₀₃ and ir _d1 , ir _d2 , ir _d3 are the resistance leakage currents ir ₁ , ir ₂ , ir ₃ as shown in FIG. 8 is actually measured and is calculated from the resistance leakage currents ir ₁ , ir ₂ , ir ₃ . That is, the resistance leakage currents ir ₀₁ , ir ₀₂ , ir ₀₃ are obtained as values when the charging time t = 0 in the relational expression ir = ir _0n (1 + h√t), and the resistance leakage currents ir _d1 , ir _d2 and ir _d3 are obtained as differences between the measured resistance leakage currents ir ₁ , ir ₂ and ir ₃ and the aforementioned resistance leakage currents ir ₀₁ , ir ₀₂ and ir ₀₃ (see FIG. 3).

  In addition, about the ion movement at the time of charging, it is possible to grasp | ascertain directly from the increase / decrease in the resistance leakage current ir at the time of the charging. That is, as described above, when the resistance leakage current ir decreases, oxygen ions are released to the outside, and when the resistance leakage current ir increases, zinc ions are diffused.

(A) is a front view including a partial cross section showing a lightning arrester, (b) is a front view showing a state in which a plurality of current limiting elements built in the lightning arrester are stacked. It is a schematic block diagram which shows the apparatus equipment which repeats an electricity application and a no-electricity in an accelerated life test. It is a characteristic view which shows the resistance leakage current which flows into the current limiting element by repeating the application of electric power to the current limiting element and no electric power application. It is a schematic diagram which shows the electric potential barrier inside a current limiting element during electric power application. It is a schematic diagram which shows the electric potential barrier inside a current limiting element in the time of no electricity. Each non-Division charging time is a characteristic diagram showing the ion transfer conditions at the time of suck conductive based on resistive leakage current ir _01, ir _02, ir ₀₃ that varies by different. It is a characteristic view which shows the ion movement state at the time of no electricity based on the resistance leakage currents ir _d1 , ir _d2 , ir _d3 which change by each electricity-free time.

Explanation of symbols

1 lightning arrester 2 current limiting element ir resistance leakage current

Claims (3)

  With respect to an element in which a predetermined current as a characteristic parameter changes over time due to deterioration, in a state in which the element temperature is kept constant, charging and no charging to the element are repeated while varying the non-charging time, By measuring the change in the predetermined current flowing through the element at the time of power application, the state of ion movement inside the element at the time of no electric power application based on the change in the predetermined current that appears due to the difference in each non-electricity time. An ion movement recognition method characterized by grasping.   2. The ion movement recognition method according to claim 1, wherein the element is a current limiting element mainly composed of zinc oxide, and a predetermined current as a characteristic parameter is a resistance leakage current.   The method for recognizing ion movement according to claim 2, wherein the element is a current limiting element having a characteristic that a resistance leakage current increases with time.

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