JPH06215669A - Dc vacuum circuit breaker - Google Patents

Abstract

PURPOSE:To carry out over-current cutoff operation reliably at an as soon as possible point of time to protect a system from a short-circuit current. CONSTITUTION:A bright and dark pattern 81 and an optical sensor 8 to read this are arranged in a movable contact point 11A of a vacuum bulb IA, and light emitted from a light emitter of the optical sensor 8 is radiated to the bright and dark pattern 81, and the reflected light is received by a light receiver, and an output signal being the electric signal is inputted to a control device 7A. The control device 7A creates a closing command signal of a commutation switch 6 of a commutation circuit 10 according to this input signal, and the commutation switch 6 is closed by this signal, and a commutation current It is flowed. Thereby, a point of time when the commutation current starts to be flowed becomes a point of time after a point of time of an opening start of the vacuum bulb 1A, and the vacuum bulb 1A is opened sufficiently, and thereafter, the first zero point of an electric current Iv flowing to this comes, so that cutoff of the electric current is completed reliably at this point of time.

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 for protecting 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. 3 is a circuit diagram of a conventional DC vacuum circuit breaker. In this figure, a DC vacuum circuit breaker is connected in parallel with a vacuum valve 1, a repulsion circuit 20 for generating an electromagnetic force in a repulsion coil 2 for driving the opening / closing operation of the vacuum valve 1, and a vacuum valve 1 so as to superimpose an AC current upon disconnection. Commutation circuit 1
It consists of zero. Although the repulsion coil 2 and the vacuum valve 1 are simply connected to each other by a line, the current flowing through the repulsion circuit 20 actually flows through the repulsion coil 2 and an electromagnetic force generated between the repulsion coil 2 and a conductor plate (not shown) causes the vacuum valve 1 to move. When the movable contact 11 is driven and separated from the fixed contact 12, the breaking operation is started.

The repulsion circuit 20 comprises a repulsion coil 2, a parallel circuit of a repulsion capacitor 30 and a repulsion power source 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, and when the breaking operation is started, the repulsion switch 60 is turned on to release the electric charge of the repulsion capacitor 30 and the current in the repulsion circuit 20. As a result, the electromagnetic force is generated and the vacuum valve 1 is opened by the electromagnetic force as described above.

The commutation circuit 10 connected in parallel to the vacuum valve 1 forces the time point when the breaking current becomes zero by superimposing the alternating current I _t on the current I of the main circuit flowing through the vacuum valve 1 during the breaking operation. Is to be generated. The commutation circuit 10 is
It 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,
The commutation capacitor 3 has a commutation power source 5 in advance before the interruption
Is charged by.

The interruption operation is performed by the overcurrent relay 71 in a predetermined manner.
A signal to the effect that a value overcurrent has been detected is output to the controller 7.
The control device 7 is closed by the repulsion switch 60.
Issue S ₁The closing signal S for the commutation switch 6₂The it
Output at the same time. Figure 4 shows the breaking operation of the DC vacuum circuit breaker.
It is a wave form diagram which shows a time change of current etc. at time. This
In the figure, the horizontal axis is time and the vertical axis is each instantaneous value.
Yes, the top stage is main circuit current I and commutation current I_tSum of
Current I flowing through the vacuum valve 1 _VAnd the main circuit
Current I and commutation current I_tIs also shown. Next stage is repulsion
Repulsive current I flowing in path 20_C, The next stage is repulsion coil 2
Repulsive current I due to generated electromagnetic force_CWaveform approximately proportional to the square of
Becomes The lowermost stage shows the opening / closing operation of the vacuum valve 1. each
The time point shown on the time axis is the time point t₁Caused a short-circuit accident on the load side
Time t at which the main circuit current I begins to rise₂Is over
The current is detected and a cutoff command is output from the control device to repel
When the switch 60 and the commutation switch 6 are turned on at the same time
Point, time t₃Is the current I_VFirst zero of time t_FourIs a vacuum
When the valve 1 starts opening, time t_FiveIs the breaking current I
_VSecond zero point at time t₆Shut off the vacuum valve 1
At the time of completion.

The breaking operation of the DC vacuum 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 a current having a small rated current level flows. Until the start of the breaking operation (t ₁ <t <t ₂ ), a short-circuit accident occurs on the load side at time t ₁ , and the current I
_V rises at a rising speed according to the value of the inductance up to the short-circuit position. When it reaches a certain value, it is detected as an overcurrent by the overcurrent relay 72, and the control device 70
To the shutoff command S ₂
There is output, and the commutation switch 6 commutation circuit 10 and the rebound switch 60 of the repulsive circuit 20 is turned at the same time at time t _2, the repulsion current I _C and commutation current I _t starts flowing at the same time. The commutation capacitor 3 and the repulsion capacitor 30 are maintained in a state of being charged to a predetermined voltage by the commutation power supply 5 and the repulsion power supply 50, respectively. Since the commutation circuit 10 and the repulsion circuit 20 are both LC series resonance circuits, an AC current that oscillates at the resonance frequency and the peak value determined by their circuit constants flows.

The electromagnetic force generated in the repulsion coil 2 is the current I _t.
Since it is approximately proportional to the square of, it does not relate to the direction of current flow. On the other hand, the commutation current I _t as the current flows in a direction opposite to the first half-wave main circuit current I in the first half-wave as shown in order to zero point is generated in the breaking current between the The commutation capacitor 3 is charged. Normally, the commutation circuit 10 and the resonance frequency of the commutation circuit 10 are set to about several kHz. Until the vacuum valve is opened (t ₂ <t <t ₄ ), the commutation current I _t is superimposed on the main circuit current I, so that the cutoff current _IV flowing through the vacuum valve 1 starts to decrease. On the other hand, when a repulsive current I _C flows through the repulsive coil 2, an electromagnetic force is generated, which serves as a driving force for opening the vacuum valve 1. When the vacuum valve 1 is in the closed state, a contact force of a magnitude indicated by the chain line in the figure for bringing the contacts into contact with each other at a predetermined pressure is applied, so at time t ₄ when the electromagnetic force becomes large enough to overcome this contact force. Only then does the vacuum valve 1 start opening. Even if the contact opening is started, the gap between the electrodes is short-circuited by the arc and the current _IV continues to flow. Until current interruption of the vacuum valve _{(t 4 <t <t 5} ) current I current I _V to time t ₅ that the second zeros of _V flows continues but after this point has expired arc at this time t ₅ No current flows, and the current cutoff operation of the vacuum valve 1 ends. However, at time t ₅ , the vacuum valve 1 is in the process of opening the electrode, and at this time, the inter-electrode withstand voltage value must withstand the recovery voltage after the current is once interrupted.
If this is not the case, the current will flow again after passing through the zero point, and the current will be cut off at the next zero point. After the current of the vacuum valve is cut off (t ₅ <t) The opening operation of the vacuum valve 1 is completed at time t ₆ . Actually, the zero point at which the current is interrupted may be before or after time t ₆ as shown in the figure.

Current I of the vacuum valve 1_VEven if is zero
The circuit current I continues to flow. This current I flows through the commutation circuit 10.
Through the load side. That is, the main circuit
The flow I is transferred from the vacuum valve 1 to the commutation circuit 10.
Become. Time t_FiveSubsequent current I _VAnd commutation current I_tIllustrated
The waveform shows that the vacuum valve 1 current was not cut off.
The time is t_FiveAfter that, commutation current
I_tAnd the main circuit current I have the same value but opposite sign
Take shape. When the vacuum valve 1 completes opening, the rest is latched.
Irrespective of the magnitude of the electromagnetic force of the repulsion coil 2
The contact is maintained open.

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 ₅ , 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 source voltage on the left side of the figure, and eventually decreases to zero and the main circuit current 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. However, since the DC power supply (not shown) on the left side of the figure is a rectifier, current flows in the opposite direction. Therefore, the main circuit current I also remains zero after the time when the main circuit current I becomes zero, and then the commutation 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.

[0011]

The time t ₄ at which the opening of the vacuum valve 1 is started is the time when the electromagnetic force generated by the repulsion coil 2 exceeds the contact force, but in reality mechanical play, friction, etc. There is opening start time t ₄ will tend to lag behind the time exceeds this contact force, also play and friction there are variations depending on the product, also may be changed by aging. Therefore, there is a problem that it may be there for opening start time t ₄ and time t _5, even interrupting current inside the completion t ₅ is delayed by the second zero point of the vacuum valve 1 fails. If the current cutoff point is delayed, various problems such as wear of contacts and metal vapor adhering to the surrounding insulator due to the arc continuing and deterioration of insulating performance will occur.

An object of the present invention is to solve such a problem and to provide a DC vacuum circuit breaker capable of reliably breaking the breaking current when the breaking current reaches a zero point as early as possible.

[0013]

In order to solve the above problems, according to the present invention, a vacuum valve for supplying a main circuit current,
A drive device for driving the opening / closing operation of the vacuum valve, a commutation circuit which is connected in parallel to the vacuum valve and generates an alternating current superposed on the main circuit current when the vacuum valve is opened,
And a control device for controlling them, wherein the commutation circuit is composed of a commutation power source, a commutation capacitor connected in parallel to the commutation power source, and a series circuit of a commutation reactor and a commutation switch in the parallel circuit. In the DC vacuum circuit breaker, an opening detection means is provided for detecting and outputting the start of opening of the vacuum valve, and the control device is based on the output signal of the opening detection means, and the control device issues a closing command signal for the commutation switch. Is generated and output, and the opening detection means is composed of a bright and dark pattern provided on the operating rod of the movable contact of the vacuum valve and an optical sensor for reading the pattern, and the control device detects the opening. It is assumed that a predetermined time difference is provided between the output signal of the means and the closing command signal of the commutation switch that is output.

[0014]

In the structure of the present invention, the opening detection means is provided to detect the opening of the vacuum valve, and the output signal thereof is input to the control device. The control device generates an opening command signal for the commutation switch based on this input signal to open the commutation switch and flow a commutation current. As a result, the point at which the commutation current begins to flow comes after the point at which the vacuum valve is opened, so that the zero point of the current flowing through it can be reached after the vacuum valve has been fully opened. Eliminating the possibility of interruption failure.

Further, the contact opening detecting means is composed of a bright and dark pattern provided on the movable contact of the vacuum valve and an optical sensor for reading the contact, so that the contact opening detecting means becomes a non-contact and high speed contact opening means. In addition, the vacuum valve provides a sufficient recovery voltage by delaying the closing command signal of the commutation switch, which is output when the output signal of the opening detection means is input to the control device, by a predetermined time with respect to the input signal. It is possible to have the first zero occur after the pole spacing is open until it is held.

[0016]

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. The same circuit elements as those in FIG. 3 are designated by the same reference numerals, and those having basically the same functions as those in FIG. And omit detailed explanations for common matters. In this figure, a light and dark pattern 81 consisting of a black and white striped pattern such as a bar code is provided on the surface of the movable contact 11A of the vacuum valve 1A.
Light is applied to this from the light emitter of the optical sensor 8 which is not labeled, the reflected light is received by the light receiver which is not labeled, and is converted into an electrical signal before input to the control device 7A. Moving contact 11
When A is stationary, the output signal S ₃ of the optical sensor 8 does not change with time, and when the movable contact 11A moves, the output signal S ₃ has a repetitive pulse waveform. Therefore, the control device 7A to which such a signal is input may be provided with a function of detecting a change in the input signal, and the detection signal may generate and output the signal S ₂ for opening the commutation switch 6.
There are various kinds of electronic circuits for detecting the change of the input signal and generating the opening signal of the commutation switch 6, but in any case, it can be easily realized by the current electronic circuit technology, and therefore detailed description will be given. Is omitted.

FIG. 2 is a waveform diagram showing a change over time in current and the like during the breaking operation of the DC vacuum circuit breaker of FIG. 1, and detailed description of the same parts as those in FIG. 4 will be omitted. In this figure, the opening operation of the vacuum valve 1A, as described in FIG. 4, but it should be started when t ₃ when the electromagnetic force exceeds the contact force, practical mechanically as described above It is delayed by time τ ₁ due to play and friction. This time τ ₁ is not constant because of variations and aging as described above. At time t ₄ after the time τ ₁ has elapsed, the vacuum valve 1A
When the contact opening is started, this is detected by the above-mentioned optical sensor 8 and a signal S ₃ is generated and input to the control device 7A, and the time τ
Opening signal S ₂ of the commutation switch 6 rises to ₂ delayed by the time t ₅ is output. In practice the time the vacuum valve 1A is the start of opening by an output signal of the light sensor 8 with respect to the time t ₄ when starting the opening is detected there is a delay but ignored here.

The commutation switch 6 is composed of a semiconductor switch, but its operation is much faster than that of a mechanical contact such as the vacuum valve 1A. Therefore, the closing pole signal S ₂ is input to the commutation switch 6. Then, it may be closed with almost no time delay. It starts to flow commutation voltage I _t by commutation switch 6 at time t ₅ is closing, but the zero-point voltage I _V flowing through the vacuum valve 1A at time t ₆ occurs between contacts of the vacuum valve 1A at this time Since the distance is sufficiently large, the vacuum valve 1 is eventually detected at time t ₆ when the first zero point occurs.
The current interruption by A is completed. The operation of the DC vacuum circuit breaker below is the same as the above-mentioned operation, and therefore its explanation is omitted.

The time τ ₂ is set so that the vacuum valve 1A secures a sufficient distance between the electrodes at the time t ₆ at which the first zero point of the current I _V occurs, and the time delay τ ₂ must be provided. At time t _6, the vacuum valve 1A is not fully opened, and the current cutoff is completed at the second zero point. Therefore, the time from the opening of the vacuum valve 1A to the current cutoff becomes longer. Because.

In FIG. 1, the light / dark pattern 81 provided on the operating rod of the movable contact 11A is a bar code pattern in which black and white are alternately arranged. Instead of this, the right side of the figure is colored black and the left side is colored white. However, when the vacuum valve 1A is in the closed state, it may be set to reflect at the black position, and when the movable contact 11A moves, it may be set so as to cross the boundary line and shift from black to white. In this case, the output signal of the photosensor changes from Low to High by shifting from black to white, so that time is set to time t ₄ in FIG. Furthermore, the movable contact 11
Instead of shining light on the cylindrical surface of the A control rod,
It is also possible to adopt a configuration in which an optical range finder that illuminates light from the right side of the drawing to measure the moving distance is provided on the right end surface of the operation rod, and a change in the measured distance is detected by the optical range finder. Even in the case of such a configuration, it is not necessary to detect the time point at which the movable contact 11A starts to move, and it is sufficient to detect the time point or position slightly delayed.

If the above-mentioned structure is adopted, not only the breaking operation of the DC vacuum circuit breaker is surely ensured, but also if the vacuum valve 1A does not open for some reason, the overcurrent detector is detected. Since the signal indicating that the contact has been opened is not emitted from the optical sensor even when a predetermined time has elapsed from the time point t ₂ when it is detected by 71 and the cutoff command is issued, a function of taking an appropriate action assuming that the vacuum valve 1A is abnormal. Can be easily provided in the control device 7A.

[0022]

As described above, the present invention is provided with the contact opening detecting means, which detects that the opening of the vacuum valve has started, and inputs the output signal to the controller. The control device generates a commutation switch closing command signal on the basis of this input signal to close the commutation switch and flow a commutation current. As a result, the flow of the commutation current starts after the opening of the vacuum valve, so that the zero point of the current flowing therethrough can be reached after the vacuum valve is fully opened. Therefore, there is no possibility that the vacuum valve will be delayed or failed to be shut off, and a highly reliable DC vacuum circuit breaker can be obtained.

Further, by forming the contact opening detecting means by the bright and dark pattern provided on the movable contact of the vacuum valve and the optical sensor for reading the contact, a contactless and high speed contact opening detecting means can be obtained. In addition, by delaying the closing command signal of the commutation switch, which is input to and output from the control device, with respect to the output signal of the opening detection means by a predetermined time, the first zero point after the polar interval of the vacuum valve is sufficiently opened. By shortening the time from the opening of the vacuum valve to the time of completion of the disconnection, the effect of reducing the wear of the contacts of the vacuum valve can be obtained.

[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 waveform diagram showing a change over time in current or the like when the DC vacuum circuit breaker of FIG. 1 is disconnected.

FIG. 3 is a circuit diagram of a conventional DC vacuum circuit breaker.

FIG. 4 is a waveform diagram showing changes over time in current and the like during the breaking operation of the DC vacuum circuit breaker of FIG.

[Explanation of symbols]

 1 vacuum valve 11A movable contact 12 fixed contact 10 commutation circuit 3 commutation condenser 4 commutation reactor 5 commutation power supply 6 commutation switch 20 repulsion circuit 7A controller 71 overcurrent detector 8 optical sensor (opening detection means) 81 Light and dark pattern

Claims (3)

[Claims] 1. A vacuum valve for flowing a main circuit current, a repulsion circuit for driving a movable contact of the vacuum valve, and an alternating current which is connected in parallel to the vacuum valve and is superimposed on the main circuit current when the vacuum valve is opened. A commutation circuit for generating the commutation circuit, and a control device for controlling the commutation circuit. The commutation circuit includes a commutation power supply, a commutation capacitor connected in parallel to the commutation power supply, and a commutation connected in series to the parallel circuit. In a DC vacuum circuit breaker comprising a reactor and a commutation switch, an opening detection means is provided for detecting and outputting the start of opening of the vacuum valve, and the control device is based on the output signal of the opening detection means. A DC vacuum circuit breaker characterized by generating and outputting a closing command signal for a commutation switch. 2. The DC vacuum circuit breaker according to claim 1, wherein the contact opening detecting means comprises a bright and dark pattern provided on the movable contact of the vacuum valve and an optical sensor for reading the pattern. 3. The DC vacuum circuit breaker according to claim 1, wherein the control device delays the closing command signal of the commutation switch by a predetermined time with respect to the output signal of the opening detection means. .