JPH0628955A - Direct current vacuum circuit breaker - Google Patents

Abstract

PURPOSE:To reduce the number of parts, and realize cost reduction and downsizing of a device. CONSTITUTION:When a repulsion coil 2A to generate electromagnetic force to drive opening and closing operation of a vacuum valve 1 is connected/inserted in series to/in a flow changing reactor 4A of a flow changing circuit 10A, an electric current having the same waveform size with the flow changing reactor 4A is flowed simultaneously to the repulsion coil 2A, so that necessary electromagnetic force is generated. Thereby, there is no need to provide an independent repulsion circuit. As a result, since repulsion electric power supply, a repulsion capacitor and a repulsion switch to constitute the repulsion circuit become unnecessary, the number of parts can be reduced, so that cost reduction and downsizing of a direct current vacuum circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC circuit breaker used to protect the system of a DC power supply for electric railways, in which an AC current is superposed on a DC current flowing through a vacuum valve to force a moment when the instantaneous current becomes zero. The present invention relates to a direct current vacuum circuit breaker configured to cause a current interruption.

[0002]

2. Description of the Related Art In a circuit breaker having a mechanical contact, the arc generated between the contacts can be extinguished only when the breaking current reaches zero. A method is adopted in which an alternating current is superimposed to force a time when the current becomes zero.

FIG. 5 is a circuit diagram of a conventional DC vacuum circuit breaker. In this figure, the DC vacuum circuit breaker is a vacuum valve 1
And a repulsion circuit 20 for generating an electromagnetic force in the repulsion coil 2 for driving the opening / closing operation thereof, and a commutation circuit 10 which is connected in parallel to the vacuum valve 1 and superimposes an AC current at the time of interruption. The vacuum valve 1 is configured so that a current flowing through the repulsion circuit 20 flows through the repulsion coil 2 and an electromagnetic force generated between the repulsion coil 2 and a conductor plate (not shown) drives a movable contact (not shown) to start the breaking operation. The repulsion circuit 20 is composed of a repulsion coil 2, a repulsion capacitor 30, a parallel circuit of a repulsion power supply 50, and a closed circuit in which a repulsion switch 60 is connected in series. The repulsion capacitor 30 is precharged by the repulsion power supply 50. When the interruption operation is started, the repulsion switch 60 is turned on, the charge of the repulsion capacitor 30 is released, and a current flows in the repulsion circuit 20. As described above, the repulsion coil 2 receives an electromagnetic force. Is generated and the movable contact of the vacuum valve 1 is driven via a transmission device (not shown) that transmits this electromagnetic force.

The commutation circuit 10 connected in parallel to the vacuum valve 1 superimposes the alternating current I _t on the current I of the main circuit flowing through the vacuum valve 1 during the breaking operation to force the time when the breaking current becomes zero. It is what is generated. Commutation circuit 10
Is composed of a parallel circuit of a commutation capacitor 3 and a commutation power source 5, a series circuit of a commutation reactor 4 and a commutation switch 6, and the commutation capacitor 3 is charged by the commutation power source 5 in advance before the shutoff operation. There is.

FIG. 6 is a waveform diagram showing a change over time in current or the like during the breaking operation. In this figure, the horizontal axis is the time, the vertical axis is the instantaneous value of each, and the uppermost stage is the main circuit current I.
Is the sum of the commutation current I _c and the breaking current _IV flowing through the vacuum valve 1, and the main circuit current I and the commutation current I _c are also shown. The next stage has a repulsion current I _t flowing through the repulsion circuit 20, and the next stage has a waveform substantially proportional to the square of the repulsion current I _t due to the electromagnetic force generated in the repulsion coil 2. The lowermost stage shows the opening / closing operation of the vacuum valve 1, with High being "closed" and Low being "open". At the time points shown on the respective time axes, at time point t ₁ , a short circuit accident occurs on the load side and the main circuit current I starts to rise, and at time point t ₂ , an overcurrent is detected and a cutoff command is output from the control device. When the repulsion switch 60 and the commutation switch 6 are turned on at the same time, a time point t ₃ is a time point when the vacuum valve 1 is opened, and a time point t ₄ is a time point when the breaking current _IV becomes zero.

The breaking operation of the vacuum DC circuit breaker shown in these figures will be described with reference to FIG. Until the occurrence of a short circuit accident (t <t ₁ ) Assume that a short circuit accident occurred in the main circuit at time t ₁ .
Before that, the current _IV flowing through the vacuum valve is the main circuit current I, and the rated current or a current smaller than it is flowing. After the time point t ₁ until the interruption operation starts (t ₁ <t <t ₂ ), the current I _V increases at a rising speed according to the value of the inductor on the load side. When it reaches a certain value, it is detected as an overcurrent, and as a result, an interruption command is output from the control device of the DC vacuum circuit breaker, and at time t ₂ , the commutation switch 6 of the commutation circuit 10 and the repulsion switch of the repulsion circuit 20. 60 and is turned at the same time, the commutation current I _c and the resilience current I _t starts flowing at the same time. The commutation capacitor 3 and the repulsion capacitor 30 are the commutation power source 5 and the repulsion power source 5, respectively.
The state of being charged to a predetermined voltage by 0 is maintained. Commutation circuit 10, repulsion circuit 20
Since both are series resonant circuits of inductance and capacitance, an alternating current that oscillates at a resonant frequency determined by the respective circuit constants flows.

The electromagnetic force generated in the repulsion coil 2 is the current I_t
Since it is proportional to the square of, it does not relate to the direction of current flow.
On the other hand, the commutation current I_CHas a zero breaking current during the first half-wave
The first half wave as shown in the drawing to turn off
The commutation capacitor is designed so that the current flows in the direction opposite to the path current I.
Charge Densa 3 in advance. Normally, the resonance circumference of the commutation circuit 10
The wave number is about several kHz, and that of the repulsion circuit 20 is the commutation circuit 10.
A frequency about twice the resonance frequency of is selected. Until the vacuum valve is opened (t₂<T <t₃) Commutation current I to main circuit current I_tTrue by overlapping
Breaking current I flowing through the empty valve 1_VBegins to decline. one
Repulsion current I to repulsion coil 2_tBy flowing
Electromagnetic force is generated and this becomes the driving force to open the vacuum valve 1.
Become. When the vacuum valve 1 is closed, the contacts are
Since the contact force to contact with pressure is given, this contact force
When the electromagnetic force becomes large enough to overcome the
Bu1 opens. The opening distance of the vacuum valve 1 is as small as a few mm.
Therefore, the time difference between the start and end of opening is small, so in this figure
The time difference is shown as zero. Time t₃Open with
However, the gap between the electrodes is short-circuited by the arc and the current I_VContinues to flow
to continue. When the vacuum valve 1 opens, it will be latched later.
Even if the electromagnetic force falls below the contact force, it will close again.
There is no. Until the vacuum valve current is cut off (t₃<T <t_Four) This current I_VWhen t crosses zero_FourUp to current I_VContinues
Then, at this point t_FourNo current flows thereafter Vacuum valve
1 ends the current interruption. After vacuum valve current interruption (t_Four<T) Current I of vacuum valve 1_VThe main circuit current I is
Keep flowing. This current I passes through the commutation circuit 10 to the load side.
Will flow to. That is, the main circuit current I is
This means that commutation from the lube 1 to the commutation circuit 10 has occurred. Time t
_FourSubsequent current I _VAnd commutation current I_tThe illustrated waveform of is a vacuum
When the current of valve 1 is not cut off
And actually t_FourAfter that, the commutation current I_tAnd main circuit
The current I has a waveform whose value matches and whose sign is opposite.

Since the commutation capacitor 3 is connected in series to the commutation circuit 10, the main circuit current I charges the commutation capacitor 3. The charging direction is opposite to that before the interruption operation is started. Before the interruption operation is started, the right side of the figure is + and the left side is −, whereas after the time t ₄ , the left side of the figure becomes +. Be charged. As a result, the voltage applied to the load side on the right side of the figure becomes a value obtained by subtracting the charging voltage of the commutation capacitor 3 from the power supply voltage on the left side of the figure, and eventually decreases to zero until the main circuit voltage I also becomes zero. become. Since the main circuit has an inductance, resonance occurs with the capacitance of the commutation capacitor 3 and the phenomenon is a little more complicated than the above, but since the DC power supply on the left side of the figure is usually a rectifier, the opposite direction Therefore, no current flows through the switch 6. Therefore, after the time when the main circuit current I becomes zero, the main circuit current I also remains at zero, and then the switch 6
The load side is completely cut off from the power supply side by opening the switch, and the breaking operation as the DC vacuum circuit breaker is completed.

If the opening time t ₃ of the vacuum valve 1 is later than the time t ₄ of the current zero point, the current is interrupted at the next current zero point t ₅ and the current starts from the opening time t _3. Since the period between the breaking times t ₅ becomes long, and during this period, there is a problem that the contact between the electrodes is short-circuited by the arc and the wear of the contacts becomes large, the opening time t ₃ is the time of the first current zero point. It is set to be before t ₄ . Therefore, as described above, the resonance frequency of the repulsion circuit 20 is set to be about twice as high as that of the commutation circuit 10 so that the first rising of the electromagnetic force becomes sharp.

[0010]

By the way, the repulsion circuit 2
Since 0 and the commutation circuit 10 are separate circuits, different resonance frequencies can be adopted as described above. Therefore, capacitors 3 and 3 of the respective circuits are used for that purpose.
0, a plurality of circuit elements having similar functions such as power supplies 5 and 50 for charging these, and switches 6 and 60 are used, so that the DC vacuum circuit breaker becomes large and the cost increases. There is a problem.

An object of the present invention is to provide a DC vacuum circuit breaker which solves such a problem and can reduce the circuit elements to reduce the size and cost of the apparatus.

[0012]

In order to solve the above-mentioned problems, according to the present invention, a vacuum valve, a repulsion coil for driving the opening and closing of the vacuum valve by an electromagnetic force, and a main circuit current when the vacuum valve is opened. A commutation circuit for generating an alternating current that is superposed on the commutation power source, the commutation circuit including a commutation power source, a commutation capacitor connected in parallel to the commutation power source, the parallel circuit, the commutation reactor, and the commutation switch. In a direct current vacuum circuit breaker in which a series circuit of and is connected in parallel to the vacuum valve, the repulsion coil is inserted into the commutation circuit to form a part of the inductance of the commutation reactor. And the commutation reactor are connected in series, or the repulsion coil and the commutation reactor are connected in parallel, or the repulsion coil is the first repulsion coil. Composed of two of repulsion coil, the first
It is assumed that the repulsion coils of 1 are connected in series and the second repulsion coils are connected in parallel with the commutation reactor.

[0013]

In the structure of the present invention, the repulsion coil for generating the electromagnetic force for driving the opening / closing operation of the vacuum valve is connected to the vacuum valve in parallel so that the alternating current is caused to flow through the vacuum valve during the breaking operation. By configuring it to be part of the inductance of the commutation reactor by inserting it into the commutation circuit of, the current of the same waveform as that of the commutation reactor flows in the repulsion coil at the same time, and electromagnetic force is generated.
By properly setting the insertion position of the repulsion coil and its inductance value in relation to that of the commutation reactor, it is possible to generate the electromagnetic force required for the shutoff operation of the vacuum valve without providing an independent repulsion circuit.
The inductance of the commutation circuit is the combined inductance of the commutation reactor and the repulsion coil. Also, when the repulsion coil is connected in series with the commutation reactor and inserted, the same current as the commutation reactor flows through the repulsion coil, or when the repulsion coil is connected in parallel with the commutation reactor and inserted, the inductance of each The current is distributed in inverse proportion to and the waveform becomes the same. Alternatively, the repulsion coil may be divided into a first repulsion coil and a second repulsion coil, the first repulsion coil may be connected in series with the commutation reactor, and the second repulsion coil may be connected in parallel with the commutation reactor and inserted. .

[0014]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a circuit diagram of a DC vacuum circuit breaker showing an embodiment of the present invention, in which the same circuit elements as those in FIG.
For functions which are similar but different in function, detailed description will be omitted by adding a subscript A to the reference numerals in FIG.
In this figure, the repulsion circuit 20 of FIG. 5 is not provided, but instead, the repulsion coil 2A is inserted in the commutation circuit 10A, and in this figure, it is connected in series to the commutation reactor 4A.

In the case of FIG. 5, since the charging energy of the repulsion capacitor 30 of the repulsion circuit 20 is about one third of that of the commutation capacitor 3 of the commutation circuit 10, the capacitance value and charging voltage of the commutation capacitor of FIG. Assuming the same as in FIG. 5, the inductance of the repulsion coil 2A is about 1/3 of the commutation coil 4 and a reasonable value. Along with this, the commutation coil 4A
The inductance of 2 may be 2 to 3 times that of the commutation coil 4. Instead, the repulsion coil 2A has a commutation circuit 1
Since a current having a resonance frequency of 0 A flows, the frequency cannot be increased in order to make the rising of the electromagnetic force steep as shown in FIG.

Since the repulsion coil 2A does not work as a simple inductor but works for driving the vacuum valve 1, the equivalent damping resistance is increased by that amount, and the commutation capacitor 3 is used to compensate for this. There are some differences from the conventional ones, such as increasing the charging voltage of, but the difference is small. 2 is a circuit diagram of a DC circuit breaker showing another embodiment of the present invention. What is different from FIG. 1 is that the repulsion coil 2B is connected in parallel to the commutation reactor 4B. Since they are connected in parallel, the current sharing between the repulsion coil 2B and the commutation reactor 4B is inversely proportional to their respective inductances. The commutation inductance is the same as that of FIG. 5, and the repulsion coil 2B is
Assuming that the magnetic energy of the commutation reactor is 1/3 of the whole, the inductance of the commutation reactor 4B is 2 /
3 times, that of the repulsion coil 2B becomes 3 times, and in this case also, the commutation reactor 4B may be smaller than the conventional one.

FIG. 3 is a waveform diagram similar to FIG. 6 assuming FIG. 1, and description of the same items as in FIG. 6 will be omitted. In this figure, the commutation current I _C and the repulsion current I _t have the same waveform, the same value, and the same starting point. In this figure sufficiently large set electromagnetic force repulsion coil 2A is generated in the large inductance of the repulsion coil 2A against the contact force of the vacuum valve 1, the commutation current I _t is is set relatively small.

The time difference between the time point t ₄ the commutation current I _t is relatively small set in which the time t ₂ of the cut-off operation start since breaking current is cut zeros is relatively large, the electromagnetic force of repulsion coil 2A is large time difference between the opening time t ₃ of the set time t ₂ of the cut-off operation start since the vacuum valve 1 is reduced, as a result, time t ₃ is open the vacuum valve 1 is earlier point in time t ₄ Since the breaking current I _V becomes zero after a while, the breaking of the vacuum valve 1 is completed at this time t ₄ .

FIG. 4 is a waveform diagram similar to FIG. 3 but under different conditions, and it is assumed that the repulsion coil 2B of FIG. 2 is connected in parallel to the commutation reactor 4B. In this figure, the commutation current I _t is relatively large, and assumes a case of setting the electromagnetic force is relatively small, the commutation current I _t
Is large, the time difference between the time point t ₂ at which the breaking operation starts and the time point t ₄ at which the breaking current I _V crosses the zero point is small, and the time difference at the opening time point t ₃ is large, so that the time point t ₃ is changed to the time point t _4.
As a result, the current interruption is not performed at the time point t ₄ because the contact has not been opened yet, and the current interruption is performed only at the time point t ₅ when the next zero point is crossed. In such a case, since the time difference between the opening time t ₃ and the current interruption time t ₅ is large and a current peak is included in the period, there arises a problem that the arc energy is large and the contact wear is large. However, in general, vacuum valves are switches with small contact wear that endure high-frequency breaking operations, so in a DC vacuum circuit breaker that operates during a short circuit accident in an electric railway, the increase in contact wear may not be a problem. is there.

In order to reduce the time difference between the time point t _{3 and} the time point t _2, it is sufficient to increase the electromagnetic force generated by the repulsion coil 2A or 2B. For that purpose, the commutation reactor 4 is used.
The inductance ratio with A or 4B may be set appropriately. Further, in order to increase the time from the time point t ₂ to the time point t ₄ , it is sufficient to reduce the commutation current. For that purpose, it is easiest to lower the charging voltage of the commutation capacitor 3.

In any case, since the above-mentioned two time differences can be changed independently of each other, the repulsion coil 2A,
There is no problem even if the frequency of the current flowing through 2B is the same as that of the commutation circuit. As described above, by appropriately setting the circuit conditions, the time point t ₄ at which the breaking current I _V crosses the zero point and the opening time point t ₃ can be appropriately set, and various breaking operations can be performed. since the fabrication of the commutation reactor 4A and repulsion coil 2A to ensure the relationship between the time t ₄ when the conventional conditions cut opening time t ₃ the zero point similar to the view of FIG. 3 is easy. Incidentally, FIG. 3 shows the repulsion coil 4A of FIG.
Is assumed to be inserted in series, but the same time relationship as this can be realized by the commutation reactor 4B and the repulsion coil 2B in the case of parallel insertion in FIG. It is also possible to realize the condition of No. 4 by the commutation reactor 4A and the repulsion coil 2A.

Further, it is also possible to adopt a connection structure in which the repulsion coil 2A or 2B is divided into two, one of which is connected in series to the commutation reactor and the other of which is connected in parallel. Which one is selected will be determined by comprehensive judgment in consideration of various conditions in manufacturing the actual commutation circuit and the repulsion coil.

[0023]

As described above, according to the present invention, the repulsion coil has the same structure as that of the commutation reactor because the repulsion coil is inserted in the commutation circuit so as to be a part of the inductance of the commutation reactor. Waveform currents flow simultaneously to generate electromagnetic force, so by properly setting the insertion position of the repulsion coil and its inductance value in relation to that of the commutation reactor, the vacuum valve can be installed without an independent repulsion circuit. Since the electromagnetic force necessary for the breaking operation can be generated in the repulsion coil, the repulsion circuit can be omitted, and the number of parts can be reduced by this, which enables cost reduction and size reduction of the DC vacuum circuit breaker. The effect of becoming Furthermore, since the inductance of the commutation circuit is the combined inductance of the commutation reactor and the repulsion coil, the capacity of the commutation reactor can be reduced by the amount of the repulsion coil compared to the conventional commutation reactor, which also has the effect of cost reduction. can get.

When the repulsion coil is connected in series to the commutation reactor and inserted, the same current as the commutation reactor flows in the repulsion coil, or when the repulsion coil is connected in parallel to the commutation reactor and inserted. A current is distributed in inverse proportion to each inductance and the waveforms are the same, or the repulsion coil is divided into a first repulsion coil and a second repulsion coil,
It is also possible to insert the repulsion coil in series with the commutation reactor and to connect the second repulsion coil in parallel with the commutation reactor, and in each case, the inductance relationship between the repulsion coil and the commutation reactor is appropriate. The same effect as described above can be obtained by selecting.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a DC vacuum circuit breaker showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of a DC circuit breaker showing another embodiment of the present invention.

FIG. 3 is a waveform diagram of the breaking current and the like during the breaking operation of the DC vacuum circuit breaker of FIG.

FIG. 4 is a waveform diagram of the breaking current and the like during the breaking operation of the DC vacuum circuit breaker of FIG.

FIG. 5 is a circuit diagram of a conventional DC vacuum circuit breaker.

FIG. 6 is a waveform diagram showing changes over time in the current during the breaking operation of the DC vacuum circuit breaker of FIG.

[Explanation of symbols]

 1 vacuum valve 10A commutation circuit 10B commutation circuit 2A repulsion coil 4A commutation reactor 2B repulsion coil 4B commutation reactor 3 commutation capacitor 5 commutation power supply 6 commutation switch

Claims (4)

[Claims] 1. A vacuum valve, a repulsion coil for driving the opening and closing of the vacuum valve by an electromagnetic force, and a commutation circuit for generating an alternating current which flows in superposition with the main circuit current when the vacuum valve is opened. A direct current vacuum circuit breaker in which a flow circuit is a commutation power source, a commutation capacitor connected in parallel to this commutation power source, and a series circuit of this parallel circuit, a commutation reactor, and a commutation switch are connected in parallel to the vacuum valve. The DC vacuum circuit breaker according to claim 1, wherein the repulsion coil is inserted into the commutation circuit to form a part of the inductance of the commutation reactor. 2. The DC vacuum circuit breaker according to claim 1, wherein the repulsion coil and the commutation reactor are connected in series. 3. The DC vacuum circuit breaker according to claim 1, wherein the repulsion coil and the commutation reactor are connected in parallel. 4. A repulsion coil comprising a first repulsion coil and a second repulsion coil, wherein the first repulsion coil is connected in series and the second repulsion coil is connected in parallel with the commutation reactor. The DC vacuum circuit breaker according to claim 1, wherein: