MXPA06007704A - Optically ignited spark gap - Google Patents

Abstract

The invention relates to an overvoltage protector (1) comprising a spark gap (2) with opposing electrodes (3) and a light source for generating an ignition light in accordance with the trigger signals of a control unit, said ignition light being configured to directly ignite the spark gap (2). The aim of the invention, is to facilitate a reliable ignition of the spark gap. To achieve this, the overvoltage protector is equipped with an optical fibre (15) for conducting the ignition light to the spark gap (2).

Description

OPEN SPARK FLUSH DOWNLOADER FIELD OF THE INVENTION The invention relates to a protector against overvoltage with a spark gap that presents electrodes facing each other, with a light source to generate an ignition light as a function of activation signals of a control unit, the ignition light is configured to directly ignite the spark arrester. BACKGROUND OF THE INVENTION A surge protector of this type is already known from DE 197 18 660 A1. The overvoltage protector described therein has a spark gap that is composed of two electrodes facing each other. To ignite the spark arrester, a pulsed nitrogen laser is provided whose laser pulses, which are in the ultraviolet band, are diverted in a gas zone limited by the electrodes. To attach the ignition light to the spark gap surrounded by a housing, a quartz glass window transparent to ultra violet light is provided. To reduce the energy of the pulses of light needed to ignite the spark gap, a metal aerosol is provided between the electrodes so that firing electrons can be generated by photoemission. DE 198 03 636 A1 discloses an overvoltage protection system with a spark gap that can be ignited by an ignition electrode. To activate the spark gap, an ignition circuit consists of a capacitive voltage divider with an ignition capacitor, as well as an ignition switch element in which, due to the capacitive voltage divider, a lower voltage drops than on the main electrodes of the spark gap. If the voltage present in the ignition switch element exceeds a threshold value, it passes from a blocking position in which the flow of current is interrupted, to its transmission position that conducts current, so that it reaches a discharge of the ignition capacitor which causes a sparks discharge between the ignition electrode and one of the main electrodes and thus activates the ignition of the main spark arrester. Spark dischargers that can be actively ignited are also used as overvoltage protectors for components that are placed on high voltage platforms installed in isolation.

A surge protector of this type is already known according to the state of the art.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an embodiment of an overvoltage protector according to the state of the art and figure 2 shows an example of embodiment of a surge protector according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows an overvoltage protector of this type having a main spark gap 2 with main electrodes 3.

The main electrodes are connected in parallel to series capacitors that are connected to an alternating voltage network of three-phase current at a high voltage potential. Through the bridging via the spark gap, the capacitor is protected against too high voltages. The series capacitors or other electronic components to be protected are arranged in a platform 4 installed in an isolated manner supported by support supports in the form of a column, not shown graphically, in an environment that is at ground potential. In this way, the main electrode 3 drawn in the lower part of FIG. 1 is, for example, at a high voltage potential corresponding to that of platform 4, while the main electrode 3 drawn on the upper part of FIG. Figure 1 is located at the high voltage potential of the three-phase network. A voltage between approximately 60 kV and 160 kV falls between the main electrodes, so that the components arranged on the platform 4 are designed for this voltage drop.

To activate the spark arrester 2 in an active manner, an ignition circuit 5 is provided with an ignition electrode 6, the ignition circuit 5 having a capacitive voltage divider with a first capacitor 7 and a firing capacitor 8. The ignition capacitor 8 can be bridged by a parallel branch in which there is disposed an activation spark gap 9 and an ohmic resistor 10 connected in series thereto. The trigger spark gap 8 can be bridged by an electronic control system 11 in its transmission position, in which a flow of current through the parallel branch is enabled and, therefore, a bypass of the ignition capacitor 8. Through bridging, the ignition electrode 6 is located at the potential of the lower main electrode 3, which, however, is spatially disposed closer to the upper main electrode 3 than the lower main electrode 3. A spark discharge is generated which jumps to the lower main electrode 3. The electronic control system 11 can be powered by the energy needed to activate the activation spark gap 9 via a power supply 12. The ignition of the trigger spark gap 9 is activated actively. In this case, a protection device 13 controls the electrical measuring variables of the three-phase current network as well as the alternating current of each phase of the three-phase current network and / or the voltage that falls on the electronic components on the platform 4 If activation conditions occur, for example, exceeding a threshold voltage in the component, the protection device 13 generates an activation signal that is transmitted to a semiconductor laser that at that moment generates an optical activation signal that is it supplies the electronic control system 11 through a fiber optic conductor 15. Upon receiving an optical activation signal, the electronic control system causes an electrical activation of the spark arrester 2. Therefore, the spark gap 2 is activated only indirectly or directly by an optical signal whose light intensity only adapts to the sensitivity of the opto-electric transducer of the electronic control system. The protection apparatus 13, as well as the semiconductor laser 14, are at a ground potential, so that their access and maintenance are simplified if necessary. By means of the optical fiber conductor 15, a safe conduction of the ignition light is made possible and at the same time the isolation between the platform 4 which is at the high voltage potential and the components 13 and 14 of the protector 1 against the overvoltage is conserved. that are on the ground potential. Due to the necessary electronic system with power supply in the platform, the previously known overvoltage protector requires many costs and effort in maintenance. The object of the invention is to provide an overvoltage protector of the type mentioned at the beginning with which a safe ignition of the spark gap is possible. The invention solves this objective by means of a fiber optic conductor to guide the ignition light towards the spark arrester. According to the present invention, the ignition light is conducted safely from the light source, through a fiber optic conductor, to the spark gap.

For this it is necessary that the material of which the fiber optic conductor is composed has an optical transparency sufficiently high for the ignition light and the absorption of light followed by a dissipative heat development is largely avoided. According to the invention, the light power needed to ignite the spark arrester is such that upon the output of the ignition light from the fiber optic conductor, a sufficient number of free charge carriers are provided by photo-emission and / or multi-photon absorption or other effects, carriers that are accelerated by the electric field prevailing between the electrodes of the spark gap and form an arc of light. In the context of the invention, for example, one of the electrodes of the spark arrester is grounded, while the other main electrode is at a higher potential relative to it. This case, however, is not relevant in practice. However, in a preferred embodiment of the invention, the main electrodes are arranged on an electrically insulated placed platform which is at a high voltage potential and is intended to support components that can be connected to a high voltage three-phase current network and the Light source is connected to ground. In other words, the light source is not available on the platform but in the environment that is connected to ground and with which the light source is connected in an electrically conductive manner. In this regard, the overvoltage protector serves to protect components arranged on the platform, such as capacitors, coils and the like. The fiber optic conductor acting in an insulating manner extends between the platform and the light source connected to ground so that control of the spark gap is possible while maintaining the insulation of the platform with respect to the ground potential. Conveniently, the light source has a pumping laser that is configured to optically pump a fiber laser, an active fiber laser means being configured in a section of the fiber optic conductor. Said section of the fiber optic conductor is provided with an optically active material that absorbs the pumping light so that with a sufficiently high pumping power it is possible to invert the population. In this case, the material of the mentioned section of the optical fiber conductor facilitates the laser process. By means of the fiber laser, an expensive coupling of the ignition light in the optical fiber conductor is avoided. The light expands rather after the output of the laser resonator of the fiber optic conductor in the same fiber optic conductor, so that high firing powers can be generated in the fiber optic conductor as a function of the pumping power. As pumping lasers, any pumping lasers are well known by the expert. In this way, the pumping laser, for example, the solid-body laser, such as an nd-YAG laser or a semiconductor laser having an emission wavelength in the absorption range of the optically active particles of the laser of fiber. Advantageously, an optical system for focusing the ignition light is provided. According to this advantageous variant, an optical system is provided on the platform between the spark arrester and the end on the output side of the fiber optic conductor which, after a corresponding alignment, causes a focusing of the ignition light in the area of gas that is limited by the main electrodes. By grouping the ignition light, the intensity of light in the focus area is so high that due to the non-linear interaction between gas molecules and laser light, for example, by multiphoton absorption, electrons are generated free or, in other words, an optical disruption induced by laser in the spark gap. Through the electric field prevailing between the main electrodes, the free electrons are accelerated in such a way that, due to the avalanche effect that originates, an arc of light is formed between the electrodes that causes a voltage drop in the component that goes to protect yourself Advantageously, the ignition light is conducted on a surface of the electrode that is directed to the facing electrode. In this convenient variant, the so-called photoemission is used for the activation of sparks. In this case, the ignition light interacts with the surface material of the electrode. Due to this interaction, electrons are released from the electrode material leading to activation of the spark gap. In this regard, a focus of the ignition light is also possible. In a different manner to this, an orientation of the fiber optic conductor is selected such that the surface of the main electrode is disposed in the path of the ignition light exiting the fiber optic conductor. In this case, an unfocused ignition light, for example, strikes the electrode surface at a right angle or at an acute angle. In both variants it is decisive that, due to the interaction between the electrode material, a necessary number of free charge carriers is provided to activate the spark gap. This prevents the end of the fiber optic conductor from melting in the spark gap.

In a further configuration of the invention, the ignition light impinges transversely to the electric field between the main electrodes and the ignition light is conducted along the surface of a main electrode and, in addition, causes the electrons to escape from the electrode material. surface. Also here the photoemission effect activates the sparks discharge. Advantageously, the free end of the fiber optic conductor opposite the light source is disposed in an electrode. According to this advantageous variant, the light beam leaves the optical fiber conductor in parallel to the field lines of the electric field prevailing between the main electrodes. To protect the optical fiber conductor from the fusion, the output end of the fiber optic conductor is disposed embedded in a main electrode such that the fiber optic conductor remains separated from the ignition light arc. In a preferred embodiment, the spark gap is part of an ignition circuit for igniting a main spark gap. The main spark gap is connected, for example, parallel to a component that is to be protected against overvoltage. In this case, the spark arrester may have several partial spark arresters to increase the resistance to tension which are arranged in series with each other and only one of which is turned on directly by the light. Thanks to the ignition of only one or a part of the partial spark arresters connected in series, the voltage that falls on the partial spark arresters that have not yet been turned on increases, so that they also ignite. This is valid correspondingly for the series connection of spark arresters that are not part of an ignition circuit, but are arranged directly parallel to the component to be protected. In other words, any connection of spark arresters according to the present invention is possible. Other suitable variants and advantages of the invention are the object of the following description of embodiments of the invention with reference to the figures of the drawing, in which the components acting in the same way are provided with the same reference numbers, and Figure 1 shows an example of an overvoltage protector according to the state of the art and Figure 2 shows an example of an overvoltage protector according to the invention.

Figure 1 shows a previously known embodiment example of a protector 1 against overvoltage according to the state of the art that was already described above. FIG. 2 shows an exemplary embodiment of an overvoltage protector 1 according to the invention which is connected in parallel to a component, not shown graphically, arranged on platform 4, such as, for example, a high-voltage capacitor. In this case, the high-voltage capacitor is connected in series to a phase of a high-voltage three-phase current network. To avoid large differences in potential, the components that can be coupled with the high-voltage cable of the three-phase power network are arranged on the platform 4, which is supported in isolation, for example by means of ceramic support supports, cast resin or similar in an environment located at the ground potential. In the embodiment shown, the surge protector 1 comprises a main spark gap 2 which is composed of main electrodes 3 and which can be ignited by the ignition electrode 6. The ignition circuit 5, which is arranged on the platform, as the ignition electrode, serves for activation and, therefore, is at a high voltage potential. The ignition circuit 5 is composed of a capacitive voltage divider consisting of the capacitor 7, as well as the ignition capacitor 8, which are connected in series with each other. The ignition capacitor 8 can be bridged by a bridging branch in which the resistor 10 is disposed in series and an ignition spark gap 9 is used as a spark arrester. In contrast, the protection device 13, as well as a pump laser 16, are arranged at ground potential. The pumping laser 16 serves, in contrast to the laser 13 according to FIG. 1, not to generate an ignition light that can be coupled to the fiber optic conductor 15, but to pump a fiber laser 17 which is configured as a conductor section 15. fiber optic and consists of a base crystal that is endowed with optically active particles. The transparent base crystal to the pumping light of the pumping laser 16 helps the optically active particles in the creation of the population inversion, so that operation of the fiber laser 17 is made possible. The protection technique apparatus 13 is connected to transducers not shown graphically, such as voltage meters, so that the voltage falling on a component to be controlled can be fed to the protector apparatus 13.

The overvoltage protector 1 shown in FIG. 2 acts as follows: The protection device 13 compares the voltage values fed by the voltage meter, for example, with a threshold value. In a different manner from this, the protective device derives a voltage value from the current values of the measuring devices. If the voltage values exceed the threshold value, the protective device 13 activates an electrical activation pulse which is fed to the pump laser 16. After receiving the activation pulse, the pump laser 16 generates a pump light that releases a laser pulse from the fiber laser 17. The laser pulse of the fiber laser 17 is called Auz of ignition. The ignition light starting from the fiber laser 17 is directed through the fiber optic conductor 15 to the spark arrester 9 which is sealed by a housing, not shown. The casing is filled with a gas. In this case, the free end of the fiber optic conductor is arranged in the housing in such a way that the ignition light coming out of the optical fiber conductor 15 impinges in the gas zone limited by the electrodes transverse to the generated electric field by the electrodes of the trigger spark gap 9. The light of the fiber laser 17 is so intense that it generates an optical spark gap in the trigger spark gap 8 and, therefore, the spark spark gap 8 is ignited. By means of the connection already described in relation to FIG. 1, the spark gap of the spark arrester 3 is generated, so that the component connected in parallel is protected from excessively high voltages. In an exemplary embodiment that deviates from this, not shown graphically, the fiber optic conductor (s) are directed directly towards the spark arrester. Therefore, the main spark gap can be turned on optically. In this way, an expensive ignition circuit is no longer needed. The cost advantages obtained by this offset the costs for the pumping laser and the fiber laser.

Claims (7)

1. NOVELTY OF THE INVENTION
2. Having described the present invention, it is considered as a novelty and therefore, property is claimed as contained in the following: CLAIMS 1.- Protector (1) against overvoltage with a spark gap (2) that has electrodes (3) facing each other, with a light source for generating an ignition light as a function of activation signals of a control unit, the ignition light being configured to directly ignite the spark arrester (2), characterized by a conductor ( 15) of optical fiber to drive the ignition light to the spark gap (2). 2. Protector (1) against overvoltage according to claim 1, characterized in that the electrodes (3) are arranged on a platform (4) placed in an electrically insulated manner that is at a high voltage potential and is intended to carry components which can be connected to a high voltage three-phase voltage network, and because the light source is connected to ground.
3. 3. Protector (1) against overvoltage according to claim 1 or 2, characterized in that the light source has a pump laser (16) that is configured for the optical pumping of a fiber laser (17), a active means of the fiber laser (17) in a section of the fiber optic conductor (15).
4. 4. Protector (1) against overvoltage according to one of the preceding claims, characterized by an optical system for focusing the ignition light.
5. 5. Protector (1) against overvoltage according to one of the preceding claims, characterized in that the ignition light is led to a surface of the electrode (3) that is directed to the facing electrode (3).
6. 6. Protector (1) against overvoltage according to one of the preceding claims, characterized in that the free end of the optical fiber conductor (15) opposite the light source is arranged in an electrode (3).
7. 7. - Protector against overvoltage according to one of the preceding claims, characterized in that the spark gap is part of an ignition circuit (5) to ignite a main spark gap.