JP2529980B2 - Electric power system using vacuum trigger gap device - Google Patents

Description

The present invention relates to a power system using a trigger discharge type vacuum gap device, and in particular, controls a trigger current energization period according to a main current. Accordingly, the present invention relates to the control of the vacuum trigger / gap device that can maintain the main-to-main gap in a stable conductive state and can always provide a good and stable closing operation regardless of the load current level.

(Prior Art) In a conventional vacuum gap device 1, as shown in FIG. 5, both end openings of an insulating cylinder 2 are airtightly closed by end plates 3a and 3b to form a vacuum container. On a pair of main electrodes 4
a and 4b are arranged to face each other, and the main electrode 4a is connected to the end plate 2a via the current-carrying shaft 5a.
The main electrode 4b is supported by the end plate 3b via a hollow current-carrying shaft 5b, and a trigger electrode 7 is provided via an insulator plate 6 in proximity to one or both of the main electrodes 4a and 4b. There is.

Then, when discharging the main electrode, first, a pulse is applied from the pulse source 8 between the trigger electrode 7 and the main electrode 4b on the side close to the trigger electrode 7, and a minute discharge 9 is generated during this period. The plasma generated thereby is injected between the main electrodes. As a result, the main power supply 10 is connected to the load 11.

By the way, there are many places where the application of the vacuum gap device is expected. For example, when connecting to the commercial frequency circuit of the power transformer, if the commercial frequency AC voltage is instantly connected at zero voltage, the exciting current will flow too much and the iron core will be saturated, causing a large inrush current to flow into the power transformer and Therefore, there is a demand for synchronous closing in which the voltage phase is detected and the voltage is applied at the maximum value of the voltage, and the application of the vacuum gap difference is also required for this synchronous closing.

Normally, a load current of several hundred amperes flows on the load side of the power transformer even when the power transformer is turned on, so that the vacuum gap device operates sufficiently stably.

(Problems to be Solved by the Invention) However, there are many cases where the secondary side is connected to a large-sized magnetic coil through a full-wave rectifier circuit as in a nuclear fusion device. In this case, the current increases to a large current in a few tens of seconds, so that it is impossible to cope with the operation time within a maximum of several hundreds of μs like the operation of a normal vacuum gap device.

The present invention has been made in view of the above points, and an object thereof is to be able to maintain a conductive state even for a load in which a main current having a slow rising speed flows, and a stable trigger that is always good. An object is to provide an electric power system using a vacuum trigger gap device that provides operation.

[Structure of the Invention] (Means for Solving the Problems) The present invention is an application of a new phenomenon relating to the trigger mechanism in the vacuum pouring discovered by the present inventors in order to achieve the above object.

First, the conventional dielectric breakdown between electrodes and creepage dielectric breakdown in a vacuum are as follows. That is, it is well known that when a strong electric field is applied between electrodes facing each other in vacuum, so-called field emission electrons are emitted, and this determines a discharge phenomenon between electrodes.

Regarding creeping dielectric breakdown in vacuum, electrons generated by strong field emission at point P shown in FIG. 6, so-called triple point consisting of cathode-insulator-vacuum, fly along the electric field, and insulator 6 Collides with the surface of the and emits secondary electrons from the surface. The secondary electrons again fly along the electric field and are accelerated to re-collide with the surface of the insulator 6 and emit secondary electrons again. Usually, the secondary electron emission coefficient δ on the surface of the insulator 6 is larger than 1, so that the number of electrons increases due to this repetition. In addition, release of the adsorbed gas from the surface of the insulator 6 and electron avalanche in this gas. The grown and multiplied electron beam impact-heats the pole portion 4c of the cathode 4b, which has a positive polarity with respect to the trigger electrode 7 to evaporate the metal vapor, thereby causing a creeping insulator breakdown to form a trigger discharge 9. It is.

Heretofore, little consideration has been given to what happens to the state of the discharge part over time.

The present inventors have studied the above-mentioned trigger phenomenon in detail and found the following new facts. The trigger characteristic is shown in FIG. 3, but as can be seen from the figure, when the trigger current I _T flows, the main current I _M flows. In the figure, the trigger current I _T flows as a high frequency current, but as can be seen from the figure, the main current I _M slightly decreases at zero high frequency current but rises toward the next peak, and is constant. It can be seen that stable discharge occurs when the main current reaches the value I _C.

From this, the present inventors have been able to find out an important phenomenon that the main current I _M flows as long as the trigger current I _J flows at a constant value I _{T, C} or more. That is, the trigger current I _T
It can be seen that the gap between the main parts can be maintained in the conductive state by flowing the.

By applying this phenomenon, it is possible to apply a large inductance load to the vacuum trigger gap device as in the embodiments described below. That is,
When a coil with a large L value is turned on from the DC power source E, Or Becomes If L is a magnetic field coil for a fusion device, for example, L = 2 ^(H) , E = 600 ^(V) , Since such a coil is on the secondary side of the step-down transformer and the vacuum trigger gap device is on the primary side, for example, if a 10: 1 transformer is used, In the example Becomes

Therefore, it takes about 1 second to reach the minimum current (several + A) required for stable operation of the vacuum trigger gap device.

As is well known, in the conventional trigger gap device, the trigger ends in a few hundreds of μs at the longest, so that it is impossible to cope with the current that gradually increases over several seconds. Further, since there is no known existence of means for dealing with the current gradually increasing by vacuum discharge, there is no means for such a case.

However, as in the phenomenon newly found by the present inventors, the vacuum gap is in the conductive state as long as the trigger current of a certain value or more flows, so that the trigger current can be increased even with a slow current increase as shown in equation (3). It can be dealt with by maintaining the required period for several seconds or more.

Therefore, the present invention is directed to a vacuum container, a pair of main currents opposed to each other in the vacuum container through a main gap, and a trigger arranged in a hollow trigger space provided in at least one of the main currents. It has a discharge part, and this trigger discharge part comprises a main electrode having a hollow trigger space and a trigger electrode provided via an insulator, and supplies the main current flowing from the main power source to the load via the main gap. The main current detection unit for detection and the control unit for controlling the time for supplying the trigger current to the trigger electrode by the output of the main current detection unit are added.

(Operation) When the pulse source that is the trigger source operates, the trigger current flows from the pulse source to the trigger discharge part of the vacuum trigger gap device. As a result, the trigger discharge section becomes conductive, and the main current begins to flow. As shown in FIG. 4, if the trigger current I _T is larger than I _{T, C} as given by the following equation I _T I _{T, C} (5), the trigger discharge part has an effective resistance of several Ω or less. Therefore, the main current gradually increases as shown in FIG. 3, and the discharge is established when the stable main current I _M is reached.

Actually, the change in the main discharge current I _M is detected by the main current detection unit and sent to the control unit. The control unit controls the trigger power supply so that the trigger current I _T satisfies the expression (5) until the condition that the main current I _M is given by the following expression I _M I _C (6) is satisfied.

Therefore, regardless of the state of the load, the vacuum trigger gap device maintains the main electrode gap in the conductive state, so that the main current I _M increases, and when the formula (6) that can maintain stable discharge is established, the trigger power supply is controlled. Since the part stops, it can be seen that stable switching operation is performed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
In FIG. 1, the vacuum trigger gap device 1 is
The main electrodes 4a and 4b are
And the trigger electrode 7, and the trigger current I is the trigger power supply 12
Is supplied via a lead wire. In this vacuum trigger gap device 1, for example, a load 13 containing a large inductance L and a power source 10 (voltage F) are connected.
Further, the trigger power supply 8 of the vacuum trigger / gap device 1 is controlled by the control unit 14, and the main current value is input to the control unit 14 by the main current detector 15. Further, the external command is issued by the external command terminal 16 Is given to the control unit 14.

When operating the vacuum trigger / gap device 1 configured as described above, first, an operation start command from the outside is a command terminal.
16 is supplied to the control unit 14 to operate the trigger power supply 12 to cause the trigger current I _T to flow between the trigger electrode 7 and one of the main electrodes 4b and establish a conduction state between the pair of main electrodes 4a and 4b. .

Thus the main current I _M starts to be supplied to the load 13 from the main power source 10. This main current (load current) I _M is detected by the main current detector 15 and given to the control unit 14. Therefore, the control unit 14
Trigger current I _T (≧ I _{T, C} ) until expression (6) is satisfied
Keep the trigger power supply 12 in the operating state so that the current continues to flow.

Therefore, since the main electrodes 4a, 4b are in a low resistance conductive state, the main current gradually increases even in the case of a large inductive load, and finally I _M ≧ I _C , resulting in a stable discharge and conduction between the electrodes. The state is established. At this point, the control unit 14 stops the operation of the trigger power supply 12.

After that, since the main current I _M is in the stable discharge region, it can be seen that the vacuum trigger gap device 1 maintains the conductive state and the switching operation is established in FIG.

In addition, although the vacuum trigger gap device is targeted as the trigger gap device in the above-described embodiment, a device such as a gas gap or an ignitron may be used.

Further, although the above-mentioned embodiment shows the case of application to a DC circuit, it can also be applied to an AC circuit by adopting a dual trigger method.

Further, although the vacuum trigger gap device is the same as the conventional one in the above-mentioned embodiment, it may be configured as shown in FIG. 2, which is optimum for the system of the present invention. That is, the trigger portion shown in detail in the figure is constituted by the trigger electrode 7 supported in the hollow portion of the one main electrode 4b through the insulator 6, and the surface of the insulator plate 6 is made of metal or semiconductor. The coating 6a is formed. This allows the trigger to be triggered by current instead of voltage,
The trigger device has good controllability, and is optimal for the vacuum trigger gap device of the above-described embodiment.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the conduction state of the trigger gap device can be maintained for an arbitrary time, and the closing operation can be performed regardless of the load state. This effect is particularly effective when a vacuum trigger / gap device is used, and has an advantage that it can be used for circuit breaking as necessary due to stable closing operation and excellent vacuum gap breaking performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a sectional view showing a different structure of a trigger portion of a vacuum trigger gap device of the present invention, and FIG. 3 is a relation between a trigger current and a main current. 4 is an explanatory view showing the relationship between the trigger current and the equivalent resistance between main electrodes, FIG. 5 is a configuration diagram of a power system using a conventional vacuum trigger gap device, and FIG. 6 is a vacuum. It is a model figure of a middle creeping discharge mechanism. 1 ... Vacuum trigger / gap device 3 ... Vacuum container 4a, 4b ... Main electrode 7 ... Trigger electrode 10 ... Main power supply 12 ... Trigger power supply 13 ... Load 14 ... Control unit 15 ... Main current detection vessel

Claims (2)

(57) [Claims] 1. A vacuum container, a pair of main electrodes opposed to each other with a main gap in the vacuum container, and a trigger discharge arranged in a hollow trigger space provided in at least one of the main electrodes. The trigger discharge part comprises a main electrode having a hollow trigger space and a trigger electrode provided through an insulator, and a main current flowing from a main power source to a load through the main gap. Power using a vacuum trigger / gap device, characterized in that a main current detection unit for detecting a current and a control unit for controlling a time for supplying a trigger current to the trigger electrode by the output of the main current detection unit are added. system. 2. A power system using the vacuum trigger gap device according to claim 1, wherein a metal or semiconductor film is formed on the surface of the insulator of the trigger discharge part.