JP6202304B2 - Arc generation prevention device - Google Patents

Description

  The present invention relates to an arc generation prevention device provided in a high-voltage circuit breaker that turns on and off a high-voltage power supply in order to safely and reliably cut off, turn on, and switch a high-voltage power system.

In order to introduce a smart grid concept including long-distance transmission that enables renewable energy use and power interchange from large-scale solar power generation systems and wind power generation systems in the main power system, high-voltage direct current power is handled freely There is a need for a compact, ultra-high withstand voltage power converter that can be used. In such a new power system, not only in the case of equipment maintenance or failure, but also when the voltage of the power supply source fluctuates abnormally due to fluctuations in renewable energy, etc., between the power supply source and the load side It is necessary to shut off the circuit breaker provided in the circuit and protect the load side.
In addition, when a part of the power network breaks down, etc., a plurality of circuit breakers or a switch that combines the circuit breakers (hereinafter collectively referred to as “breakers” including such circuit breakers, switches, and switches). It is necessary to form a power network that bypasses the failure location and ensure power transmission.

  Conventionally, in a high voltage system such as a main power system, a gas circuit breaker or a vacuum circuit breaker equipped with a switch that is mechanically turned on / off is used to cut off or switch over an ultra high voltage power line. It is common to do. However, if an attempt is made to connect or disconnect the contact of the circuit breaker, a strong arc is generated, and the operation is not smoothly performed due to welding or the like, and there is a danger that the contact is damaged early. In particular, in DC power transmission required for smart grids, it is difficult to design such a circuit breaker or a switch with a circuit breaker.

  In a gas circuit breaker, the arc can be extinguished by blowing an inert gas to the contact point, but it does not fundamentally suppress the generation of the arc, and the contact electrode is consumed too much, which is assumed in smart grids. Cannot be turned on and off frequently. For this reason, it is necessary to increase the capacity of the gas circuit breaker and the vacuum circuit breaker, and it is necessary to secure a large amount of capital investment and space such as a dedicated circuit breaker room.

  In order to solve this problem, Patent Document 1 provides a switching element made of a photoconductive element so as to bypass a high-speed mechanical switch made of a vacuum circuit breaker, and irradiates the photoconductive element with light from an irradiation light source. Thus, it is described that a current can be passed so as to bypass the high-speed mechanical switch, and turning off in this state disconnects the generator and the power network without generating an arc. If the mechanical switch can be turned off at a minimum arc voltage or a minimum arc current due to photoelectron emission of the photoconductive element, it is possible to suppress arc generation.

Japanese Patent No. 4532735

Technical Tidbits Brush Wellman Japan Hitokuchi Technical Information VOL.4 No.10 Contact Arc Discharge October 2002

However, in Patent Document 1, for example, when switching an ultrahigh voltage power line, in order to generate a desired bypass current, it is necessary to irradiate the photoconductive element with an irradiation light source with an enormous output. For this reason, in order to secure a bypass current necessary to prevent arc generation, the power supplied to the irradiation light source must be increased, resulting in a poor response, increased energy consumption, and a huge irradiation light source. This causes the problem that the current bypass device becomes very large and costly. Further, since a high voltage is applied to the photoelectric element itself, it is difficult to reduce the size in order to avoid creeping discharge.
Therefore, in the present invention, by using a diamond PN junction diode electron source (including a PIN junction diode electron source), it is possible to reduce power consumption and to secure a necessary bypass current at a low cost and a small size. An object of the present invention is to provide an arc generation prevention device.

In order to achieve the above object, an arc generation preventing device according to the present invention is provided on a power line connecting a high voltage power supply and a load via a high voltage circuit breaker, and a bypass circuit for bypassing the high voltage circuit breaker, and a bypass circuit A vacuum power switch using a diamond PN junction diode as an electron emission source, and an on / off switch for a diode power supply provided in the vacuum power switch and applied in a forward direction to the diamond PN junction diode. Prior to turning on / off the voltage circuit breaker, the on / off switch is turned on, and the voltage between the contacts of the high voltage circuit breaker is reduced by passing the electron emission current accompanying the electron emission from the diamond PN junction diode to the bypass circuit. at the minimum arc voltage drop stages than by that allows a high voltage circuit breaker on and off, high voltage And to prevent an arc generated due to the cross-sectional unit of the on-off.

According to the present invention, prior to turning on and off the high voltage circuit breaker, the vacuum power switch is turned on, and the electron emission from the diamond PN junction diode or PIN junction diode electron source is bypassed to bypass the high voltage circuit breaker. The electric current accompanying is supplied. As a result, when the high-voltage circuit breaker is turned on / off, the voltage between contacts that suddenly increases when the contact leaves or the current between contacts that suddenly increases when the contact approaches is instantaneously reduced to generate an arc. Can be reliably deterred.
In addition, vacuum power switches using diamond PN junction diodes or PIN junction diodes have the characteristics of the elements themselves that have extremely high voltage resistance and power transfer efficiency while being compact. The circuit breaker and switching device arranged in the system can be made compact and low in cost, and the durability and reliability can be improved.

FIG. 1 shows a schematic diagram of an experimental apparatus for investigating the characteristics of a vacuum power switch using a diamond PN junction diode. FIG. 2 is a diagram showing the relationship between the electron emission current I _A of the vacuum power switch generated when the diamond PN junction diode is turned on and off, and the voltage V _A between the anodes. FIG. 3 is a graph showing the relationship between the electron emission current I _A and the electron emission efficiency α with respect to the voltage of the diode power supply. FIG. 4 is a diagram showing the transition of the voltage between contacts and the current between contacts when arc discharge occurs. FIG. 5 is a diagram showing Example 1 of the present invention. FIG. 6 is a diagram showing the relationship between the contact voltage of the mechanical switch and the electron emission current. FIG. 7 is a diagram illustrating transition of the voltage between contacts and the current between contacts in the first embodiment. FIG. 8 is a diagram showing the transition of the voltage between contacts and the current between contacts in a conventional mechanical switch. FIG. 9 is a diagram showing a second embodiment of the present invention.

The present inventors have developed a vacuum power switch using a diamond PN junction diode electron source as an ideal electron emission source for flowing a large current at high efficiency and low voltage in a vacuum (2012/12). 10th (Japan) National Institute of Advanced Industrial Science and Technology (National Institute for Materials Science) In this vacuum power switch, when the diamond surface is covered with hydrogen atoms, the energy position of the free electrons in the diamond is higher than that of the outside vacuum, and the negative electron affinity that allows electrons to jump out freely into the vacuum. It takes advantage of the fact that it has a surface.

Diamond covered with hydrogen is stabilized by a strong covalent bond between a hydrogen atom and a carbon atom, is stable in the atmosphere, and is stable up to a high temperature of 800 ° C. in a vacuum. Thus, when the diamond PN junction diode covered with hydrogen is turned on, electron emission occurs.
However, since the dielectric constant of diamond is smaller than that of other semiconductor materials, the amount of electrons that can move around at room temperature is small, and the current that flows during room temperature operation is small. On the other hand, in diamond, electrons and holes are stable in a state of being combined as free excitons at room temperature, and have a long lifetime with a high crystal quality i layer with few impurities, and tend to have a high density. Then, from the surface of the hydrogen-terminated diamond, electron emission due to the free excitons can be obtained with high efficiency. Therefore, a PIN junction type diamond PN junction in which an intrinsic layer (i layer) in which impurities are mixed as low as possible is inserted between a p layer added with boron and an n ⁺ layer added with phosphorus at a high concentration. A diode was used as an electron emission source. However, it is assumed that “PN junction” is included in “PN junction”.

The present invention makes use of the excellent characteristics of such diamond PN junction diodes to achieve circuit breaker miniaturization, cost reduction, durability, and reliability improvement for switching high voltage power lines. The schematic of an experimental apparatus is shown.
Inside the vacuum power switch 1 having a vacuum chamber, an anode 3 is disposed at a position about 100 μm away from directly above the diamond PN junction diode 2.
Further, the positive side of the diode power supply 4 is connected to the p-layer side terminal of the diamond PN junction diode 2, and the negative side is connected to the n ⁺ layer-side terminal. A switch 5 is provided between the positive side of the diode power supply 4 and the p-layer side of the diamond PN junction diode 2. Here, the p-layer side terminal is connected to the ground via the switch 5, but it operates even if the n ⁺ layer-side terminal is connected to the ground.

The anode 3 is connected to a 10 kV high-voltage DC power source 7 through a 200 MΩ load 6. In this experimental example, the area that determines the current capacity of the diamond PN junction diode 2 is such that the surface facing the anode 3 is 1.9 × 10 ⁻³ square centimeters (about 0.44 mm square).

According to such a configuration, when the switch 5 is turned on, the diode power supply 4 is applied to the diamond PN junction diode 2, and electrons are emitted from the i layer having substantially the same potential as the p layer side terminal toward the anode. Will be. Due to the electron emission, an electron emission current I _A flowing from the high-voltage DC power source 7 to the ground side via the load 6 is generated.

FIG. 2 shows the relationship between the electron emission current I _A generated when the switch 5 is turned on and off, and the voltage V _A between the diamond PN junction diode 2 and the anode 3.
As can be seen from this result, at the moment when the switch 5 is switched from OFF to ON, the diode power supply 4 is applied between the p-layer side terminal and the n ⁺ layer-side terminal of the diamond PN junction diode 2 via the load 6. As a result, the electron emission current I _A is generated, and the voltage V _A between the diamond PN junction diode 2 and the anode 3 decreases from 9.8 kV to 160 V according to the operating point of I _A = 48 μA.

At this time, the input power to the diamond PN junction diode 2 is 82.6 mW, which is a product of the diode voltage 23.6 V, the diode forward current I _G = 7 mA, and the driving time 0.5 seconds, but to the load Output power was 231 mW as a product of a load voltage of 9.64 kV, a current of 48 μA, and a driving time of 0.5 seconds, and a power transfer efficiency of 231 / (82.6 + 231) = 73.7% was obtained.

On the other hand, when the switch 5 is switched from on to off, the current I _A becomes 0 _A and the voltage V _A returns to 9.8 kV after about 0.3 seconds.
Thus, even if the diamond PN junction diode 2 is a very small element having an area facing the anode 3 of about 1.9 × 10 ⁻³ square centimeters and the switch 5 is turned off, the diamond PN junction diode 2 is applied with 10 kV applied to the anode 4. On the other hand, a substantially electrically insulated state can be maintained.
The time constant of 0.3 seconds is determined by the time constant of the circuit, and it has been observed that the on / off speed of the electron emission current by the PN junction diode is less than 1 ms.

FIG. 3 shows the relationship between the electron emission current I _A (left vertical axis) and the electron emission efficiency α (I _A / I _G ) with respect to the voltage (horizontal axis) of the diode power supply 4. In the measurement, the anode voltage (high-voltage power supply voltage) was fixed at 100 V with no load.

As can be seen from this result, when a forward voltage of 30 V is applied to the diamond PN junction diode 2, I _A is 345 μA, I _G is 40 mA, and the electron emission efficiency α (I _A / I _G ) is 0 It will be .86%.

From the above, it is understood that when the area (S _mesa = 1.9 × 10 ⁻³ square centimeters) is determined as the area for determining the current capacity of the diamond PN junction diode 2, a maximum current density of 180 mA / cm ² can be obtained. . Therefore, if the diamond PN junction diode 2 is used as 10 cm square, an electron emission current I _{A of} 18 _A can be obtained.

Thus, the vacuum power switch using the diamond PN junction diode exhibits high insulation against a high voltage of 10 kV when the switch 5 is turned off, while the I _A -V _A characteristic is V _A = V when the switch 5 is turned on. Since I _A rises from 0, the resistance becomes almost 0, the current flowing through the load can be suppressed by the current accompanying the electron emission, and the power consumption at the time of on is low, and it has high on / off durability. .
Furthermore, since electrons in a vacuum can follow a speed approximately 10 times that in a solid, that is, a speed close to the speed of light, it is possible to follow a voltage fluctuation more rapidly than a solid element.
Therefore, in the present invention, utilizing this characteristic, the diamond PN junction diode is used as a switching element that bypasses a mechanical switch such as a vacuum circuit breaker that cuts off and switches high voltage.
As a result, it is possible to reliably prevent an arc generated when the mechanical switch used as the high voltage circuit breaker is turned on / off with a small size, low cost, and low power consumption.

First, the generation mechanism and conditions of arc discharge are analyzed.
Arc discharge occurs both on and off in all mechanical switches and circuit breakers with contacts, whether direct current or alternating current. Although the mechanism has not yet been elucidated in detail, as shown in FIG. 4, arc discharge lasts when a voltage higher than the minimum arc voltage occurs between the contacts and a current higher than the minimum arc current flows. It is.
Therefore, if either one of the conditions can be avoided, the arc will not last, so the current flowing through these mechanical switches and circuit breakers is actively bypassed in parallel with the mechanical switches and circuit breakers to be maintained, In addition, even when contact between the contacts of the circuit breaker is insufficient or not, the potential difference (voltage) generated between the contacts when the circuit breaker performs switching of the high-voltage power line, etc. is below the minimum arc voltage. By making it, it is possible to prevent arcing.

From this point of view, when the time evolution of the voltage V between the contacts and the current I between the contacts when the arc is ignited in the case of the contact OFF in FIG. 4, the current I between the contacts is I ₀ before the start of the contact OFF, Greater than the minimum arc current (I ₀ > I _arc ).
When the contact is turned off, the contact area gradually decreases between the contacts, and I ₀ concentrates in a small region, so that the contact resistance increases. When the supply of high voltage from the supply power source continues, V increases due to an increase in contact resistance, while I ₀ is maintained due to circuit inertia. When this develops in time in a positive feedback manner, Joule heat concentrates in the remaining contact portion, and eventually develops to evaporation of the electrode metal material. At this moment, a large amount of electrons and positive ions are generated, accelerated by a high electric field generated at a high V and a small contact distance, and further evaporation and ionization of the electrode material proceeds in an avalanche while satisfying the discharge duration condition. Therefore, it finally reaches the arc firing.

  On the other hand, as shown in FIG. 1, when the diamond PN junction diode 2 is turned on and a sufficient electron emission current is obtained, when the anode voltage is low, the diamond PN junction diode 2 flows through a vacuum power switch responsible for electron emission. The current is at a low level. However, when the mechanical contactor or circuit breaker is turned on / off, the contact state between the contacts becomes critical and the anode voltage rises rapidly. Since it is possible to follow at a speed close to the speed of light ten times faster in the solid, it is possible to suppress an extreme increase in the anode voltage in a range smaller than the minimum arc voltage and to secure a sufficient current level that the circuit breaker should bear.

An embodiment of an arc generation preventing device utilizing the characteristics of such a diamond PN junction diode will be described with reference to the drawings.
[Example 1]
As shown in FIG. 5, a mechanical switch 8 for turning on and off the high voltage power source is provided between the DC power supply source and the load side, such as a vacuum circuit breaker having two contacts. Yes. In the circuit that bypasses the mechanical switch 8, an arc generation preventing device comprising a vacuum power switch 1 using a diamond PN junction diode is provided.

Specifically, when a wind power generator with a power generation amount of 1.8 MW (rated voltage 100 kV, rated current 18 A) is used as a power supply source, the diamond PN junction diode 2 used for the vacuum power switch 1 has a withstand voltage of 100 kV or more. Thus, when the switch 5 is turned on, it is necessary to secure an electron emission current of I _A = 18 _A by applying the diode power supply 4. For this reason, in this embodiment, a 10 cm square diamond PN junction diode 2 was used. .

The mechanical switch 8 is turned on / off by the following procedure.
First, the case where the mechanical switch 8 is turned off to shut off the power supply source and the load will be described.
First, before the contact of the mechanical switch 8 is turned off, the switch 5 provided in the diamond vacuum power switch 1 is turned on, so that the voltage from the diode power supply 4 is applied to the diamond PN junction diode 2 and the diode current. _IG is played.

FIG. 6 shows the relationship between the voltage of the anode 3, that is, the voltage between the contacts of the mechanical switch 8 and the electron emission current. When the switch 5 is off, a high voltage is applied to the anode 3. However, the electron emission current I _A is maintained at almost zero.
On the other hand, when the switch 5 is turned on and a forward diode current I _G flows through the diamond PN junction diode 2, the emission current increases from a low voltage simultaneously with the increase of the inter-contact voltage V. This emission current characteristic depends on the voltage of the diode power supply 4 applied to the diamond PN junction diode 2 in the forward direction (the diode current I _G determined as a result).

Therefore, when the total current value flowing through the mechanical switch 8 is I, the electron emission current value is I _A , and the total current flowing to the load side is I ₀ , the mechanical switch is satisfied while satisfying the relationship of I ₀ = I + I _A. Current V to be applied to the diamond PN diode 2 by the voltage V _G applied to the diamond PN junction diode 2 of the diode power supply 4 so that the voltage V between the contacts 8 is V _X lower than V _arc and I _A = I _0. Define _G = I _GX .
In this embodiment, the electron emission current value I _A is selected to be I ₀ when the voltage between the contacts shown in FIG. 6 is V _X which is sufficiently smaller than V _arc .

Thus, with the off mechanical switch 8, also increases the contact voltage V, and before the off operation start of the mechanical switch 8, by applying a voltage V _G of the diode power supply 4 to the diamond PN junction diode 2 Therefore, the electron emission current I _A becomes almost I ₀ and I can be made almost _{0 A} at the contact voltage V _X which is much lower than V _arc , so that the mechanical switch 8 is completely turned off. It is possible to reliably prevent the occurrence of arcing until it reaches.
Of course, it is not always necessary to reduce I to almost 0 A, and it may be selected so as to eliminate the arc generation condition by making it less than the minimum arc current I _arc .

Thus, in the entire process in which the mechanical switch 8 is turned off, the load side and the power supply side continue to be electrically connected due to the conduction of the bypass circuit, and a current of about 18 A continues to flow.
On the other hand, as shown in FIG. 4, if there is no bypass circuit, the voltage V between the two contacts of the mechanical switch 8 increases rapidly and reaches the arc ignition condition with the minimum arc voltage.
By providing the vacuum power switch 1 with the diamond PN junction diode 2 in the bypass circuit and applying the output of the diode power supply 4 before the mechanical switch 8 is turned off, the electron emission current I _A causes the contact between the two contacts. Sufficient electrons can be prepared to carry a current corresponding to the total current I ₀ flowing through the current. Moreover, since the diamond PN junction diode 2 has an extremely high electron emission response, in the entire process in which the mechanical switch 8 is turned off,

Total current (I ₀ ) = Current flowing through mechanical switch 8 (I) + Bypass current (I _A )

I can be decreased rapidly while satisfying.
For this reason, even if the contact resistance is suddenly increased due to the OFF operation of the mechanical switch 8, the increase in V can be reliably suppressed.

In this way, the mechanical switch is controlled by actively controlling I _G so that the electron emission current value I _A = I ₀ as a bypass current so that V = V _X <V _arc is finally satisfied. Even if the 8 contacts are completely separated, the arc does not ignite.
Thereafter, if the switch 5 is turned off again, the power consumption by the vacuum power switch 1 can be reduced to 0 thereafter. FIG. 7 summarizes the time evolution of the voltage V between the contacts of the mechanical switch 8 and the current I between the contacts according to a series of procedures during the on / off operation.
On the other hand, for comparison, FIG. 8 shows an outline of time development of the voltage V between the contacts of the mechanical switch 8 and the current I between the contacts according to a series of procedures at the time of on / off operation in the conventional case where no vacuum power switch is used. Shown in

To connect the power supply and the load (voltage V _E) at time t _0, at time t _1, switch the vacuum power switch 1 at time t ₀ immediately before the start of the on-mechanical switch (mechanical SW) 8 (Vacuum SW) 5 is turned on, and a voltage V _G is applied from the diode power supply 4. At this time, the vacuum power switch is operating at the operating point (V _X , I ₀ ) in FIG. 6, and the voltage between the contacts of the mechanical switch 8 is V _X. Further, the power supply source and the load are connected, the rated current I ₀ flows, and the voltage (V _E −V _X ) is supplied to the load.
Here, V _X is sufficiently smaller than V _E and can be selected to be within an allowable variation of V _E.
Conventionally, when the mechanical switch 8 is turned on at time t ₁ , as shown in FIG. 8, as the contacts are connected from time t ₁ to t ₂ , both the voltage and current between the contacts satisfy the arc firing conditions. There is a dangerous timing, and arc firing is inevitable.
On the other hand, in the present invention, as shown in FIG. 7, it is assumed that the current I flowing through the contact increases at the timing when the connection of the contact progresses from time t ₁ to t ₂ and exceeds the maximum arc current I _arc. However, since the voltage between the contacts has already dropped to V _X which is sufficiently smaller than the minimum arc (ignition) voltage V _{arc, arc} ignition can be reliably avoided. Thereby, generation | occurrence | production of the powerful arc which produces welding can be prevented reliably.
Then, at the stage of the ON operation is completely finished the time t ₂ after a time t ₃ of the mechanical switch 8, by turning off the switch 5 of the vacuum power switch 1, by stopping the power supply from the diode power supply 4 Thus, the ON process of the mechanical switch 8 is completed.

Next, the mechanical switch 8 is turned off as follows. When the mechanical switch 8 starts to be turned off at time t ₁ ^′ in order to cut off the power supply source and the load, the switch 5 in the vacuum power switch 1 is turned on (I _G = 0) at time t ₀ ^′ immediately before that. To I _G = I _GX ), and the voltage V _G is applied from the diode power supply 4. In this case, if 0 the resistance between the contacts of the mechanical switch 8, since the terminal voltage remains at 0, an operational point (0,0) near the state of FIG. 6, I = I _0, I _A remains 0.
In this state, when the mechanical switch 8 is turned off, the contact area between the contacts decreases with the dissociation of the contacts and the contact resistance increases rapidly, but the vacuum power switch is already turned on, and the operating point of FIG. A smooth and quick transition can be made from (0, 0) to (V _X , I ₀ ). That is, along with this, the electron emission current I _A rapidly increases, and the total current value I flowing through the mechanical switch 8 decreases rapidly while satisfying the relationship of I ₀ = I + I _A. That is, even if the contact resistance between the contacts of the mechanical switch 8 increases rapidly, the voltage between the contacts of the mechanical switch 8 maintains the anode voltage V _X of the vacuum power switch.
Conventionally, when the mechanical switch 8 is turned off at time t ₁ ^′ , as shown in FIG. 8, the voltage and current between the contacts are increased with the opening of the contact of the mechanical switch 8 from time t ₁ ^′ to t ₂ ^′. Both have dangerous timings that satisfy the arc firing condition, and arc firing is inevitable.
On the other hand, in the present invention, as shown in FIG. 7, the maximum arc current I is decreased while the current I flowing through the contact decreases at the timing when the contact of the mechanical switch 8 proceeds from time t ₁ ^′ to t ₂ ^′. _Although there is a timing exceeding the _arc , the voltage between the contacts remains lowered to V _X which is sufficiently smaller than the minimum arc (ignition) voltage V _arc , so that the arc ignition can be surely avoided. Thereby, generation | occurrence | production of the strong arc which opposes the interruption | blocking operation | movement of a circuit breaker can be prevented reliably.
Thereafter, the power supply from the diode power supply 4 is stopped by turning off the switch 5 in the vacuum power switch 1 at the stage of time t ₃ ^′ after time t ₂ ^′ when the mechanical switch 8 is completely turned off. Thus, the off process of the mechanical switch 8 is completed.
Note that when the vacuum power switch 1 is turned on and off, there is no mechanical contact, so the arc does not ignite.

In order to realize the above sequence, for example, when switching a high-voltage power line, for example, a push button is provided in the vacuum power switch 1, and an on / off command for the switch 5 in the vacuum power switch 1 is given by a command from this push button. It is preferable to provide a control device that performs sequence control so that an operation command to the actuator that turns on and off the mechanical switch 8 is automatically and time-sequentially transmitted.
At this time, by providing an on-off command delay circuit for the switch 5, rise characteristics of the diode current I _G, by changing the descending characteristic, for example, the rising speed of the electron emission current with a diamond PN junction diode 2, falling It is also possible to reduce the speed, suppress voltage fluctuations with respect to the load, and further reduce the impact on the load.
The above operation can be performed by an automatic sequence operation using a microcomputer, an abnormality detector in the power system network, and the like, similar to the existing vacuum circuit breaker.

  In this embodiment, one 10 cm square diamond PN junction diode 2 is provided. However, the area of the diamond PN junction diode 2, that is, the capacity can be selected according to the rated voltage and rated current of the power supply source. it can. Also, for example, a required number of 1 cm square diamond PN junction diodes 2 may be connected in parallel so as to correspond to the rated current of the power supply source.

[Example 2]
The first embodiment is based on a DC power supply source, but the second embodiment is based on an AC power supply source. In FIG. 9, the power supply source is an AC generator, and in this embodiment, the vacuum power switches 1A and 1B are attached in the reverse direction.
Since the vacuum power switches 1A and 1B both output the electron emission current I _A only in the forward direction, the vacuum power switches 1A and 1B have the same effects as the vacuum power switch 1 of the first embodiment depending on the phase.

As described above, according to the present invention, for example, even when a power supply source with a power generation amount of about 1.8 MW is used, a diamond PN junction diode 2 of 10 cm square is used as a diamond PN junction diode used for a vacuum power switch. By using it, it is possible to reduce power consumption and to secure a necessary bypass current at a low cost and in a small size. Moreover, the diamond PN junction diode has the characteristics of the element itself because it has extremely high withstand voltage and power transmission efficiency. For example, it is widely used as a circuit breaker, switch, etc. arranged in an ultra high voltage power system. Can be expected.

1 Vacuum Power Switch 2 Diamond PN Junction Diode 3 Anode 4 Diode Power Supply 5 Switch 6 Load 7 High Voltage DC Power Supply 8 Mechanical Switch (High Voltage Circuit Breaker)

Claims (3)

A bypass circuit provided on a power line connecting a high voltage power source and a load via a high voltage circuit breaker, and bypassing the high voltage circuit breaker;
A vacuum power switch provided in the bypass circuit and using a diamond PN junction diode as an electron emission source ;
An on / off switch of a diode power supply provided in the vacuum power switch and applied in a forward direction to the diamond PN junction diode ;
Prior to the high voltage circuit breaker on and off, to turn on the on-off switch, said bypass circuit, by flowing the electron emission current due to the electron emission from the diamond PN junction diode, the high voltage blocking By preventing the high-voltage circuit breaker from being turned on and off by preventing the high-voltage circuit breaker from being turned on and off when the voltage between the contact points of the breaker drops below the minimum arc voltage. An arc generation preventing device for a high-voltage circuit breaker characterized by being made as described above. The current capacity of the diamond PN junction diode is determined such that the current value of the electron emission current is a current value that flows from the high-voltage power source to the load when the high-voltage circuit breaker is on. The arc generation preventing device for a high voltage circuit breaker according to claim 1. An actuator for operating the high-voltage circuit breaker is provided, and a control device is provided for controlling on / off of the actuator and the on / off switch by sequence control by operating the vacuum power switch. The arc generation preventing device for a high voltage circuit breaker according to claim 1 or 2 .

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