JP3067428B2 - Abnormality monitoring device for DC breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for monitoring an abnormality of a DC circuit breaker used in a DC circuit.

[0002]

2. Description of the Related Art FIG. 4 is a circuit connection diagram showing a configuration of a conventional DC circuit breaker abnormality monitoring device. The DC circuit breaker 1 is configured such that a parallel circuit of a vacuum valve 2, a surge absorbing element 3, and an oscillating current generating circuit 4 is interposed in series with a main circuit 6 together with a primary winding of a main circuit current transformer 5. The vacuum valve 2 has a built-in contact that is opened and closed mechanically, and the surge absorbing element 3 is made of, for example, a zinc oxide element. The oscillating current generating circuit 4 is composed of a series circuit of a capacitor 7, a reactor 8, and a trigger switch 9. The capacitor 7 is DC-charged by the charger 10. By closing the trigger switch 9,
The oscillating current generation circuit 4 outputs an oscillating current i _o having a frequency that resonates between the capacitor 7 and the reactor 8 between the electrodes of the vacuum valve 2.

Further, in FIG. 4, an output signal 5S of the secondary winding of the main circuit current transformer 5 is input to the fault detector 11. As described later, the accident detector 11 receives the signal 5S, and outputs the opening command signal 11 for the vacuum valve 2.
A and a closing command signal 11B of the trigger switch 9 are output. On the other hand, an oscillating current detecting current transformer 12 is interposed in the oscillating current generating circuit 4, and an output signal 12S of the current transformer 12 is provided.
Is input to the abnormality monitoring device 13. This abnormality monitoring device 1
Reference numeral 3 denotes, as will be described later, monitoring the level of the signal 12S and notifying that the DC breaker 1 is abnormal when the magnitude of the oscillating current i _o is equal to or less than a predetermined value.

FIG. 5 is a circuit connection diagram showing an example of a power system in which the DC breaker 1 of FIG. 4 is interposed. The main circuit 6 of the power system includes a rectifier 15 and a DC breaker 1 from an AC generator 14.
And to the load 16. FIG. 6 is a time chart for explaining the cut-off principle of the DC circuit breaker. FIG.
It is assumed that a ground fault has occurred at a point 6A on the load 16 side of the main circuit 6 in FIG. The upper waveform 17 shows the open / closed state of the vacuum valve 2, and the middle waveform 18 shows the open / closed state of the trigger switch 9. The lower waveform 19 (solid line) is the current I flowing through the vacuum valve 2.

[0005] In FIGS. 5 and 6, until the time t _o is providing current I _L becomes a direct current I to the load 16. At time t _o , if an accident occurs at point 6A, the accident current I starts to increase. The main circuit current transformer 5 detects this increase in current and outputs an output signal 5S. At time t ₁ when the current I flowing through the vacuum valve 2 reaches the predetermined value I _O , the accident detector 11 outputs the opening command signal 11A to the vacuum valve 2, so that the vacuum valve 2 Open to ₂ However, the current I continues to flow between the poles of the vacuum valve 2 via the arc. Next, the accident detector 11 outputs a closing command signal 11B to the trigger switch 9. Waveform 1
When the trigger switch 9 closes at time t _{3 as shown} in FIG.
The capacitor 7 starts discharging and the oscillating current i _o is
Flow into When superimposed at the vacuum valve 2 such that the polarity of the rising portion of the current i _o and the polarity of the current I are opposite to each other, the current I starts to decrease from time t ₃ as shown in a waveform 19. At time t ₄ , the vacuum valve 2
And cut off the circuit.

In FIG. 6, a dashed line waveform 20
The figure shows how the fault current I increases when the oscillating current _io is not passed, and increases toward a value (E / R) obtained by dividing the power supply voltage E by the load resistance R at the time of the fault. on the other hand,
A waveform 21 indicated by a two-dot chain line shows a subsequent temporal change of the oscillating current i _o . In FIG. 5, the surge absorbing element 3 is for absorbing the energy stored in the inductance existing in the circuit, and suppresses the surge generated between the electrodes of the vacuum valve 2 at the time of shutoff. .

A DC circuit breaker 1 as shown in FIG.
_If the value of _o is smaller than a predetermined value, the vacuum valve 2 cannot obtain a zero point and cannot be shut off. That is, the oscillating current i _o is set to be at least twice as large as the fault current I. A current transformer 12 for detecting an oscillating current is provided for monitoring the level of the oscillating current i _o . In the method of monitoring the oscillating current i _o , the vacuum circuit breaker 1 is detached from the main circuit 6 and the trigger switch 9 is closed and the oscillating current i _o flows with the vacuum valve 2 closed. The output signal 12S of the current transformer 12 is received by the abnormality monitoring device 13, and when the magnitude of the oscillating current i _o is equal to or smaller than a predetermined value, the abnormality is notified by a notification signal or a notification lamp. ing.

If the charging voltage of the charger 10 is low, the constants of the capacitor 7 and the reactor 8 are changed, or if the connection line of the oscillating current generating circuit 4 is disconnected, the oscillating current i _o becomes a predetermined value. Will not rise to the level.
Such an emergency can be detected in advance by the above-described test.

[0009]

However, in the conventional device as described above, another oscillating current detecting current transformer is provided in addition to the main circuit current transformer, and two current transformers are required. There was a problem that is. It is more economical to share as many current transformers as possible and use only one. For this purpose, it is conceivable to change the circuit configuration to superimpose an oscillating current on the primary winding of the main circuit current transformer.

It is an object of the present invention to provide an apparatus in which two current transformers are shared and only one current transformer is required.

[0011]

According to the present invention, in order to achieve the above object, according to the present invention, there is provided a vacuum valve having a built-in switching contact and interposed in series in a main circuit, and connected in parallel to the vacuum valve. A surge absorbing element, an oscillating current generating circuit for passing an oscillating current to the vacuum valve via a trigger switch, and a main circuit current transformer in which a primary winding is interposed in series in a parallel circuit of the vacuum valve and the surge absorbing element. The output signal of the secondary winding of this current transformer is received, and when the main circuit current exceeds a predetermined value, a signal for opening contacts is output to the vacuum valve and a signal for closing contacts is output to the trigger switch. In the DC breaker provided with an output fault detector, the level of the oscillating current is monitored, and when the magnitude of the oscillating current is equal to or less than a predetermined value, it is notified that the DC breaker is abnormal. And the vibration The current output terminal of the current generating circuit is connected in parallel to the series circuit of the vacuum valve and the primary winding of the main circuit current transformer, and the level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer. In addition to this configuration, both ends of the primary winding of the main circuit current transformer are short-circuited via a rectifier outside the main circuit current transformer.

According to another aspect of the present invention, there is provided a vacuum valve having a built-in switching contact and interposed in series in a main circuit, a surge absorbing element connected in parallel to the vacuum valve, An oscillating current generating circuit for applying an oscillating current to a vacuum valve via a trigger switch, a main circuit current transformer having a primary winding interposed in series in a parallel circuit of a vacuum valve and a surge absorbing element, and the current transformer An accident detector that receives the output signal of the secondary winding of, and outputs a contact opening signal to the vacuum valve and a contact closing signal to the trigger switch when the main circuit current exceeds a predetermined value. In the DC circuit breaker provided with, the magnitude of the oscillating current is monitored, and when the magnitude of the oscillating current is equal to or less than a predetermined value, it is notified that the DC breaker is abnormal, Main circuit current transformer already One primary winding, the other primary winding is short-circuited outside the main circuit current transformer and connected in series to the vacuum valve, and the current output terminal of the oscillating current generation circuit is connected to the vacuum valve and the main circuit transformer. It is connected in parallel with a series circuit with another primary winding of the current transformer, and the level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer.

[0013]

According to the configuration of the present invention, the current output terminal of the oscillating current generating circuit is connected in parallel to the series circuit of the vacuum valve and the primary winding of the main circuit current transformer. The level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer. This eliminates the need for an oscillating current detection current transformer, which was conventionally required separately, and can be achieved with a single current transformer.

In addition to this configuration, both ends of the primary winding of the main circuit current transformer are short-circuited via a rectifier outside the main circuit current transformer. If the direction of the rectifier is arranged in the forward direction with respect to the first wave of the oscillating current, the first wave of the oscillating current shunts, and half of the first current flows through the rectifier to the vacuum valve. Therefore, an oscillating current of the same magnitude as the fault current flows in the main circuit current transformer. This improves the current detection accuracy of the current transformer.

Further, according to the configuration of the present invention, the main circuit current transformer includes another primary winding. This other primary winding is shorted outside the main circuit current transformer and connected in series with the vacuum valve. A current output terminal of the oscillating current generating circuit is connected in parallel to a series circuit of the vacuum valve and another primary winding of the main circuit current transformer. The level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer. This eliminates the need for a separate current transformer for oscillating current detection, which can be achieved with a single current transformer. Furthermore, the oscillating current shunts and only half of it flows to the main circuit current transformer. Therefore, an oscillating current of the same magnitude as the fault current flows in the main circuit current transformer.
This improves the current detection accuracy of the current transformer.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
FIG. 1 is a circuit connection diagram showing a configuration of an abnormality monitoring device for a DC circuit breaker according to an embodiment of the present invention. Current output terminals 4A and 4B of the oscillating current generation circuit 4 are connected in parallel to a series circuit of the vacuum valve 2 and the primary winding of the main circuit current transformer 5. No current transformer for oscillating current detection is provided. The level monitoring of the fluctuating current i _o is performed by the abnormality monitoring device 13 receiving the output signal 5S of the secondary winding of the main circuit current transformer 5.

The other structure of FIG. 1 is the same as that of the conventional apparatus shown in FIG. The same parts are denoted by the same reference numerals, and the detailed description will not be repeated. Conventionally, two current transformers are required, but by using the output signal 5S of the main circuit current transformer 5 as well, one current transformer can be used. Obviously, the device of FIG. 1 operates in exactly the same way as the shut-off principle shown in FIG.

FIG. 2 is a circuit connection diagram showing the configuration of a DC circuit breaker abnormality monitoring apparatus according to another embodiment of the present invention. Both ends 4B and 4C of the primary winding of the main circuit current transformer 5 are short-circuited via the rectifier 22. This short circuit is performed so as not to penetrate the iron core of the main circuit current transformer 5 but to pass over the outside of the current transformer. Other configurations are the same as those in FIG. 2, the oscillating current i if for the first wave of _o Oke by arranging the direction of the rectifier 22 in the forward direction, the first wave current i of the oscillating current i _o
1 and i ₂ . The currents i ₁ and i ₂ are the oscillating currents i _o if the resistances of the conductors forming the current paths are the same.
Is half the value of As described above, the oscillating current i
_o is set to be at least twice the current I at the time of the accident. By passing half of the oscillating current i _o , i _2, through the primary winding of the main circuit current transformer 5, the main circuit current transformer 5
Will detect almost the same level of current. Therefore, the current detection accuracy of the current transformer is improved. If the rectifier 22 is not provided, a circuit is formed in which the current I flows around the external side of the main circuit current transformer 5 and flows to the load side. ing.

FIG. 3 shows another embodiment of the present invention.
Circuit connection diagram showing the configuration of the abnormal monitoring device for DC breakers
It is. 2 is different from the configuration of FIG.
Is provided with another winding 50A, and this winding 50A
A is a point short-circuited outside the main circuit current transformer 50.
You. Oscillating current i_oIs half the current i₁, I_TwoDiversion into
And the current i_TwoOnly flows through winding 50A. Main circuit current transformer
50 includes the fault current I and the oscillating current i at substantially the same level. _Two
Flows in the same manner as in the configuration of FIG.
The degree improves. Moreover, the rectification required in the configuration of FIG.
Even if the current transformer 22 is not provided, the fault current I
You will not be able to pass. Main circuit current transformer 50 is through type
Can be used even if multiple primary windings are required.
It can be easily constructed simply by penetrating the body.

[0020]

According to the present invention, as described above, the current output terminal of the oscillating current generating circuit is connected in parallel to the series circuit of the vacuum valve and the primary winding of the main circuit current transformer. The level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer. This eliminates the need for an oscillating current detection current transformer, which was conventionally required separately, and can be achieved with a single current transformer, thereby reducing the cost of the device.

In addition to this configuration, both ends of the primary winding of the main circuit current transformer are short-circuited via a rectifier outside the main circuit current transformer. This improves the current detection accuracy of the current transformer. Further, according to the configuration of the present invention, the main circuit current transformer includes another primary winding. This other primary winding is shorted outside the main circuit current transformer and connected in series with the vacuum valve. A current output terminal of the oscillating current generating circuit is connected in parallel to a series circuit of the vacuum valve and another primary winding of the main circuit current transformer. The oscillating current level is monitored by the output signal of the secondary winding of the main circuit current transformer. As a result, a single current transformer can be used, and the current detection accuracy can be improved without using a rectifier, so that the cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit connection diagram showing a configuration of an abnormality monitoring device for a DC breaker according to an embodiment of the present invention.

FIG. 2 is a circuit connection diagram showing a configuration of a DC circuit breaker abnormality monitoring device according to another embodiment of the present invention.

FIG. 3 is a circuit connection diagram showing a configuration of a DC circuit breaker abnormality monitoring device according to still another embodiment of the present invention.

FIG. 4 is a circuit connection diagram showing a configuration of a conventional DC circuit breaker abnormality monitoring device.

5 is a circuit connection diagram showing an example of a power system in which the DC circuit breaker of FIG. 4 is interposed.

FIG. 6 is a time chart for explaining the shut-off principle of the DC circuit breaker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DC circuit breaker 2 Vacuum valve 3 Surge absorption element 4 Oscillating current generation circuit 5 Main circuit current transformer 50 Main circuit current transformer 6 Main circuit 7 Capacitor 8 Reactor 9 Trigger switch 10 Charger 11 Accident detector 13 Abnormality monitoring device 22 rectifier

Claims (3)

(57) [Claims] 1. A vacuum valve having a built-in switching contact and interposed in series with a main circuit, a surge absorbing element connected in parallel to the vacuum valve, and an oscillating current flowing an oscillating current to the vacuum valve via a trigger switch. A main circuit current transformer in which a primary winding is interposed in series with a parallel circuit of a vacuum valve and a surge absorbing element, and an output signal of a secondary winding of the current transformer; And a fault detector that outputs a signal for opening a contact to a vacuum valve and outputs a signal for closing a contact to a trigger switch, respectively, when the value exceeds a predetermined value. Monitoring is performed to notify that the DC breaker is abnormal when the magnitude of the oscillating current is equal to or less than a predetermined value, and the current output terminal of the oscillating current generating circuit is connected to the vacuum valve and the main circuit. With the primary winding Connected in parallel to the series circuit, the abnormality monitoring device for a DC circuit breaker is level monitoring of the oscillating current, characterized by comprising performed by the output signal of the main circuit current transformer secondary winding. 2. The direct current cutoff according to claim 1, wherein both ends of the primary winding of the main circuit current transformer are short-circuited via a rectifier outside the main circuit current transformer. Device abnormality monitoring device. 3. A vacuum valve having a built-in switching contact and interposed in series with a main circuit, a surge absorbing element connected in parallel to the vacuum valve, and an oscillating current flowing an oscillating current to the vacuum valve via a trigger switch. A main circuit current transformer in which a primary winding is interposed in series with a parallel circuit of a vacuum valve and a surge absorbing element, and an output signal of a secondary winding of the current transformer; And a fault detector that outputs a signal for opening a contact to a vacuum valve and outputs a signal for closing a contact to a trigger switch when is greater than or equal to a predetermined value. The main circuit current transformer is provided with another primary winding when the magnitude of the oscillating current is less than or equal to a predetermined value, and notifies that the DC breaker is abnormal. The other primary winding is the main winding Short-circuited outside the current transformer and connected in series to the vacuum valve, the current output terminal of the oscillating current generating circuit is connected in parallel to a series circuit of the vacuum valve and another primary winding of the main circuit current transformer. An apparatus for monitoring abnormality of a DC breaker, wherein the level of an oscillating current is monitored by an output signal of a secondary winding of a main circuit current transformer.