JPS60187002A - Surge absorber - 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 of the Invention] The present invention relates to a surge absorber used to protect semiconductor devices such as thyristors or other electrical components from overvoltage.

[Technical background of the invention]

When configuring a thyristor conversion device by connecting a large number of thyristors in series or series-parallel in a power circuit,
DC arresters are used to protect thyristors from overvoltages such as lightning surges. On the other hand, recently, high-performance non-linear resistance elements have been developed, and gapless type surge absorbers using non-linear resistance elements have been proposed in place of conventional gapped arresters. This type of surge absorber is used by connecting a plurality of thyristors all at once in parallel, or by connecting each thyristor in parallel. FIG. 1 shows an example of the latter.

Figure 1 shows an example of application to a power transmission line, where line terminal A
A plurality of thyristors 1 connected in series are provided between the power converter and the ground terminal as part or all of the power converter. It is assumed that each thyristor 1 shown in the figure consists of one or more thyristor elements. Each thyristor 1 is connected in parallel with a partial pressure membrane circuit consisting of a capacitor t2 and a resistor 3 connected in series, and a surge absorber 5. Stray capacitance existing between the line and the top and ground is distributed between the connection point and the terminal of each thyristor and is indicated by reference numeral 4.

[Problems with background technology]

When lightning surge voltage or switching surge voltage enters the circuit in Figure 1 from terminal A, if the surge absorber 5 malfunctions for some reason and breaks down, unlike in the case of Cyrisk, the surge absorber 5 will have a high arc voltage. Therefore, the injection energy increases, resulting in the destruction of the container,
Arc is emitted to the outside and has a negative impact on peripheral equipment.
There was a risk that the accident would escalate.

[Purpose of the invention]

The present invention was made in order to eliminate the above-mentioned disadvantages, and it is an object of the present invention to provide a surge absorber that does not have the risk of exploding.

[Summary of the invention]

In order to achieve the above object, the present invention provides
A short-circuiting metal made of a metal material having a melting temperature of . According to this configuration, when the non-linear resistance element in the container is destroyed by the intrusion of a surge and an arc is generated, the short circuit metal melts and a bridge path of molten metal is created between the two electrode plates. It is possible to lower the impedance of the surge absorber, reduce the injection energy, and prevent explosion and destruction of the surge absorber.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG. This surge absorber forms a closed container with a cylindrical ceramic insulating container 6 and a pair of metal electrode plates 7 and 8 which also serve as lids that close both open ends of the container. Both electrode plates 7, 80
A nonlinear resistance element 9 made of zinc oxide (ZnO) or the like is disposed sandwiched therebetween. There is also a slight gap 10,1 in the sealed container with respect to the nonlinear resistance element 9.
Both electrode plates 7, 80 so as to form a parallel shunt through 3
Shorting metals 11, 12 and 14, 15 are provided in between. Although the detailed composition of the short-circuit metal will be described later, it is made of a metal material having a melting temperature of about 160 to 350°C in terms of temperature characteristics. Although the figure shows two gaps 10 and 13, there may be only one gap, or three or more gaps depending on the case.

When a surge of large energy enters the surge absorber configured in this manner and is installed in the power system, and the nonlinear resistance element 9 becomes unable to withstand the injected energy, the nonlinear resistance element 9 enters a penetrating state. The arc voltage in such a penetrating state is relatively high, unlike in the case of a thyristor, so the injection energy is quite large. If a short-circuiting metal is not provided at this time, the electrode plates 7 and 8 may be burnt out due to the arc, the insulating container 6 may be destroyed due to the increase in internal pressure, and the arc may jump out of the container and spread along the container. The arc continues. Such a state continues until the operation of the thyristor 1 (FIG. 1) is stopped, and there is a possibility that damage may be caused to peripheral devices of the surge absorber.

However, in the surge absorber of FIG. 2 according to the present invention, when the arc directly touches the short-circuited metals 11, 12, 14, and 15, or when the arc heat reaches them, the short-circuited metals melt, and the gap between the two electrode plates 7 and 8 is are bridged by the molten shorting metal. As a result, the arc is extinguished and does not fly out of the container. Moreover, the rise in the internal pressure of the container is also suppressed due to the extinction of the arc.

In such a surge absorber, it is essential that when the injection energy exceeds a predetermined level value, the short-circuiting metal should melt quickly within a short time on the order of milliseconds to short-circuit the electrode plates.

In order to satisfy this condition, the melting temperature must be within a predetermined range. If the melting temperature is less than 150℃, due to the temperature rise when the rated current is applied and the influence of the surrounding heat,
There is a risk that it will melt even if abnormal energy is not applied. In addition, if the melting temperature is 360°C or higher, the time until melting becomes long, and during that time, the non-linear resistance element 9 is affected by the abnormally large energy stored in the container.
There is a risk of destroying it. Therefore, in the present invention, such inconvenience is avoided by setting the melting temperature of the short-circuiting metal to 160 to 350°C as described above. This melting temperature can be easily set to a desired value by taking into consideration the specific heat, thermal conductivity, heat of fusion, latent heat of vaporization, amount used, etc. of the material.

Next, we will discuss the results of tests conducted using various material compositions as short-circuiting metals. In this test, in the surge absorber having the configuration shown in Fig. 2, a plastic insulating container 7 with a diameter of 135i+g was used, and a
While storing the nO element as a non-linear resistance element 9,
Samples were prepared in which the short-circuiting metals shown in Table 1 were housed and hermetically sealed with copper electrode plates 7 and 8. The performance of this surge absorber was evaluated by applying an alternating current of 50) Iz and approximately 3 to 4 kA.

As shown in Table 1, short-circuited metals with melting temperatures of 350°C or higher did not melt, did not undergo arc migration or transition to short-circuited conditions, and plastic containers were either destroyed or did not result in destruction. The abnormal temperature rise caused the electrode plates to melt, resulting in an unfavorable situation. On the other hand, in Comparative Example 3 where the melting point was 141° C., the short circuit metal melted down and short circuited before reaching the test target current of 3 to 4 kA. From the above, it was concluded that the melting temperature of the short-circuit metal is preferably within the range of 160 to 350°C. This conclusion is based on the fact that the alloy system of the short-circuit metal was used in Example 1.
As shown in ~6, Ag In series, Ag TB series, Zn-8n
It remains unchanged even if it changes with the system, and even if it is a pure metal as in Example 6 or an alloy system as in Examples 1 to 5, It is.

As shown in Examples 1 to 6, by providing the short-circuit metal of the present invention, the energizing voltage when the short-circuit metal exhibits a short-circuit effect ("voltage at the time of short circuit" in Table 1) is extremely low. , it can be seen that it is preferable. On the other hand, in Comparative Examples 1 to 7, destruction of the container was observed in some cases, and cases where the melting point of the short-circuit metal was high (Comparative Examples 1, 2, and 4.5) were undesirable because arc transition took time. .

Table 2 shows similar test results when using short-circuiting metals of different alloys from those in Table 1.

It can be seen that the nonlinear resistance element 9 can be well protected in this case as well.

In addition, in the above explanation, Z is used as the nonlinear resistance element 9.
Although a device made of nO is shown as an example, the present invention can be similarly applied to a device made of SiC or the like.

〔Effect of the invention〕

As described above, according to the present invention, when a surge absorber malfunctions due to the arrival of a surge, the explosion of the container is prevented by the action of the shorting metal, thereby preventing the spread of an accident due to an explosion, and preventing power transmission and distribution. The reliability of devices and switchgears can be improved.

[Brief explanation of drawings]

FIG. 1 is a connection diagram showing a thyristor conversion device provided with a surge absorber, and FIG. 2 is a longitudinal sectional view showing an embodiment of the present invention. 6... Insulating container, 7, 8... Electrode plate, 9... Non-linear resistance element, 10, 13... Gap, 11.12
, 14, 15... Short circuit metal. Applicant's agent Kiyoshi Inomata

Claims (1)

[Claims] A cylindrical insulating container, an electrode plate disposed at both open ends of the insulating container, a non-linear resistance element inserted between the two electrode plates in the insulating container, and a melting temperature of 160 to 350 ° C. and a short-circuit metal disposed with a slight gap between the two electrode plates so that the two electrode plates can be short-circuited by melting.