JP3175520B2 - DC circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker used in a DC circuit, and more particularly to a structure which can easily check a breaking operation without inputting a simulated signal of a fault current at the time of inspection.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram showing a configuration of a conventional DC breaker. The DC circuit breaker 1 is interposed in a main circuit 6, and is configured by connecting a primary winding of a main circuit current transformer 5 in series to a parallel circuit of a vacuum valve 2 and a surge absorbing element 3. Also,
An oscillating current generation circuit 4 is connected to both ends of a series circuit of the vacuum valve 2 and the 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 vibration generating circuit 4 includes 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 generating circuit 4 is connected to the capacitor 7 and the reactor 8
And outputs an oscillating current i _O having a frequency that resonates between the electrodes of the vacuum valve 2.

Further, in FIG. 5, an output signal 5S of the secondary winding of the main circuit current transformer 5 is input to an accident detector 11. As described later, the accident detector 11 receives the signal 5S, and outputs the opening signal 11A of the vacuum valve 2,
And a closing signal 11B for closing the trigger switch 9. FIG. 6 is a circuit diagram showing a power system in which the device of FIG. 5 is interposed. The main circuit 6 of the power system is connected from the AC generator 14 to the load 16 via the rectifier 15 and the DC breaker 1. Now, the load 1 of the main circuit 6 in FIG.
It is assumed that a ground fault has occurred at point 6A on the sixth side.

FIG. 7 is a time chart for explaining the principle of the DC breaker at that time. 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. Lower waveform 19
(Solid line) is the current I flowing between the poles of the vacuum valve 2.
6 and 7, until the time t _o direct current I serving as a current I _L in the load 16 is supplied. 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 a predetermined value I _O , the accident detector 11
Outputs the opening signal 11A to the vacuum valve 2 so that the waveform 1
As shown at 7, the gap between the vacuum valves ₂ is mechanically opened at time t2. 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 signal 11B to the trigger switch 9. When the trigger switch 9 is closed at time t ₃ as shown by the waveform 18, the capacitor 7 starts discharging and the oscillating current i _O flows into the vacuum valve 2. When superimposed at the vacuum valve 2 so 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 the time t ₃ as shown in a waveform 19. At time t _4, the vacuum valve 2 circuit to obtain a zero of the current I is cut off.

In FIG. 7, a dashed-dotted waveform 20 shows how the fault current I increases when the oscillating current i _O is not supplied, and the power supply voltage E is divided by the load resistance R at the time of the fault. Value (E / R). 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. 6, the surge absorbing element 3 is for absorbing the energy stored in the circuit in the amount of inductance, and suppresses the surge generated between the electrodes of the vacuum valve 2 at the time of shutoff. .
If the magnitude of the oscillating current i _O is smaller than a predetermined value, the DC circuit breaker 1 cannot obtain the zero point of the vacuum valve 2 and cannot be cut off. That is, the oscillating current i _O is set to be at least twice as large as the fault current I.

[0006]

However, the conventional apparatus as described above has a problem that the check of the shut-off operation is very troublesome. In other words, when checking a conventional DC circuit breaker,
Disconnect from the system. Next, a simulated signal of the fault current (a current signal of the same level as the current value operated at the time of the fault) was passed through the device, and it was examined whether or not the vacuum valve was reliably shut off. Therefore, a current source for generating a simulation signal is required, and wiring work for flowing the simulation signal to the test device is also required, which is very troublesome. Therefore, labor and time are required for inspection, and it has been desired to simplify the operation check of the apparatus.

An object of the present invention is to eliminate injection of a simulated signal of an accident current required for inspection.

[0008]

According to the present invention, there is provided, in accordance with the present invention, a vacuum valve having a built-in switching contact and interposed in series in a main circuit, and a surge valve connected in parallel to the vacuum valve. An absorbing element, 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 oscillating current generating circuit that supplies an oscillating current to the vacuum valve via a trigger switch. Receives the output signal of the secondary winding of the main circuit current transformer, outputs an opening signal to open the vacuum valve when the main circuit current exceeds a predetermined value, and outputs a closing signal to close the trigger switch. In a DC circuit breaker having an accident detector that outputs each signal, a test switch that can be opened and closed from the outside of the DC circuit breaker, and another closing signal that closes a trigger switch by closing the test switch. Is provided and a check circuit to force,
It is preferable that the trigger switch is closed by one of a trigger switch on signal output from the accident detector and a trigger switch on signal output from the check circuit.

[0009]

According to the structure of the present invention, there is provided a test switch which can be opened / closed from the outside of the DC cutoff, and a check circuit for outputting another closing signal for closing the trigger switch by closing the test switch. Can be The trigger switch is configured to be closed by one of a trigger switch on signal output from the accident detector and a trigger switch on signal output from the check circuit. In the event of an accident, the accident detector outputs a closing signal, closes the trigger switch, and the vacuum valve opens. On the other hand, at the time of inspection, it is the same as the conventional method until the device is once disconnected from the system. Next, by operating the test switch from the outside, the check circuit outputs a closing signal and closes the trigger switch. At this time, since the discharge current from the capacitor flows to the main circuit current transformer, if the test device is normal, the fault detector outputs an opening signal, and the vacuum valve opens.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a circuit diagram showing a configuration of a DC breaker according to an embodiment of the present invention. A closing signal 11B from the accident detector 11 and a closing signal 13S output from the check circuit 13 via the test switch 31 are input to the OR circuit 30. The OR circuit 30 outputs a signal for closing the trigger switch 9 when one of the closing signals 11B and 13S is input. Other configurations are the same as the conventional configuration described with reference to FIG. The same portions are denoted by the same reference numerals, and the detailed description will not be repeated.

In FIG. 1, in the event of an accident, the accident detector 11 outputs a closing signal 11B to close the trigger switch 9, and the vacuum valve 2 is opened, while at the time of inspection, the apparatus is temporarily disconnected from the system. Is the same as the conventional method.
FIG. 2 is a time chart for explaining an operation mechanism at the time of inspection of the apparatus of FIG. The upper waveform 32 shows the open / closed state of the vacuum valve 2, and the middle waveform 33 shows the open / closed state of the trigger switch 9. The lower waveform 34 is the current I flowing between the electrodes of the vacuum valve 2.

[0012] In Figures 1 and 2, check circuit by placing the test switch 31 at time t ₃₀ 1
The input signal 13S is input to the trigger switch 9 via the OR circuit 30 from 3 and the trigger switch 9 is closed as shown by a waveform 33. As a result, an oscillating current i _O like the waveform 34 flows from the capacitor 7 to the vacuum valve 2. When the current I becomes a predetermined value I _O at time t _10, the accident detector 1
1 is mechanically opened to the time t ₂₀ between the vacuum valve 2 pole as waveform 32 because outputs the opening signal 11A to the vacuum valve 2. Thereafter, the circuit becomes a time t ₄₀ that the current I becomes zero as shown in a waveform 34 is interrupted.

In FIG. 2, the fact that the vacuum valve 2 is not opened even when the test switch 31 is turned on indicates that an abnormality has occurred in the vacuum circuit breaker 1. This inspection method can be said to be very easy to inspect because there is no need to inject a simulated signal of a fault current unlike the conventional device. FIG. 3 is a circuit diagram showing a configuration of a DC breaker according to another embodiment of the present invention. Both ends of the primary winding of the main circuit current transformer 5 are short-circuited via the rectifier 22 outside the main circuit current transformer 5. Other configurations are the same as those in FIG.
If the direction of the rectifier 22 is arranged in the forward direction with respect to the first wave of the oscillating current, the oscillating current _IO shunts to i ₁ and i ₂ , of which i ₁ passes through the rectifier 22 Flows to With this configuration, adjustment of the oscillating current flowing in the main circuit current transformer 5 can be performed. There is no need to increase the current capacity of the main circuit current transformer 5 for the oscillating current. The operation mechanism at the time of inspection in this configuration is the same as that in FIG.

FIG. 4 is a circuit diagram showing a configuration of a DC breaker according to still another embodiment of the present invention. The main circuit current transformer 50 includes another primary winding 50A. The other primary winding 50 </ b> A is short-circuited outside the main circuit current transformer 50 and is connected in series to the vacuum valve 2. A current output terminal of the oscillating current generating circuit 4 is connected in parallel to a series circuit of the vacuum valve 2 and another primary winding 50A of the main circuit current transformer 50. The level of the oscillating current is monitored by the output signal of the secondary winding of the main circuit current transformer 50. Other configurations are the same as those in FIG. The oscillating current i _O is split into i ₁ and i ₂ , of which only i ₂ flows through the main circuit current transformer 50. With this configuration, adjustment of the oscillating current flowing in the main circuit current transformer 50 can be performed. There is no need to increase the current capacity of the main circuit current transformer 50 due to the oscillating current. The operation mechanism at the time of inspection in this configuration is the same as that in FIG.

[0015]

According to the present invention, as described above, a test switch which can be opened and closed from the outside of a DC cutoff, and a check circuit for outputting another closing signal for closing a trigger switch by closing the test switch. Is provided, and the trigger switch can be closed by either a trigger switch on signal output from the accident detector or a trigger switch on signal output from the check circuit. This eliminates the need for injection of a simulated signal of a fault current as in the conventional device, and makes inspection very simple. Therefore, inspection time and labor are greatly reduced, and maintenance costs can be saved.

[Brief description of the drawings]

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

FIG. 2 is a time chart for explaining an operation mechanism at the time of inspection of the apparatus of FIG. 1;

FIG. 3 is a circuit diagram showing a configuration of a DC breaker according to another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a DC breaker according to still another embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration of a conventional DC circuit breaker.

6 is a circuit diagram showing a power system in which the device of FIG. 5 is interposed.

FIG. 7 is a time chart for explaining the cut-off principle of the DC circuit breaker.

[Explanation of symbols]

1: DC circuit breaker, 2: vacuum valve, 3: surge absorbing element, 4: oscillating current generation circuit, 5, 50: main circuit current transformer,
11: accident detector, 30: OR circuit, 31: test switch, 13: check circuit, 11A: opening signal, 11
B, 13S: closing signal, 9: trigger switch

Claims (1)

(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 a parallel circuit in which a primary winding comprises a vacuum valve and a surge absorbing element. A main circuit current transformer, which is interposed in series, a oscillating current generating circuit that supplies an oscillating current to a vacuum valve via a trigger switch, and an output signal of a secondary winding of the main circuit current transformer, and the main circuit An accident detector that outputs an opening signal for opening a vacuum valve when the current exceeds a predetermined value and outputs a closing signal for closing a trigger switch, respectively. A test switch that can be opened and closed from the outside and a check circuit that outputs another closing signal that closes the trigger switch when the test switch is closed are provided. DC circuit breaker, wherein the on signal of the switch, by either of the input signals of the trigger switch for outputting the check circuit closes the trigger switch.