JPS601712A - Power breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power circuit breaker, particularly a high voltage DC circuit breaker.

A DC circuit that does not have a zero point for voltage or current like AC.
In particular, it is more difficult to interrupt high-voltage DC circuits than AC circuits.

Therefore, as a measure to improve the breaking ability, a breaking method as shown in the circuit diagram shown in FIG. 1 has been proposed. This method consists of a current-carrying disconnection section A1 connected in series to a current-carrying circuit (1).
For example, in parallel with the electrode (2) of a sulfur hexafluoride gas circuit breaker, the high voltage generating section B is connected to a fusible current-carrying element (3) such as a fuse.
) is sealed in an electrically insulating high-pressure container (5) together with an electrically insulating buffer material (arc-extinguishing blade) (4), and at the same time, this fusible current-carrying element (3) is connected. The fuse is selected to be cut off after the dielectric strength of the electrode (2) is recovered, and cut-off is performed by the action described below. That is, when the electrodes (2) start to open at time to according to the opening command S, an arc is generated between the electrodes (2), and the arc voltage increases as time passes due to the increase in the electrode spacing.
d) increases over time. Then the electrode (
Due to the reverse voltage action caused by the arc voltage, the current ■A in FIG. 2(b) flowing in 2) begins to commutate to the fusible current-carrying element (3) as current IB as shown in FIG. 2(C), and at time tl When the arc voltage reaches 1 in FIG. 2(d), the entire amount of commutation ends. As a result, the current 9 flowing through the electrode (2) becomes zero, so the arc during this period disappears and the dielectric strength between the electrodes (2) returns to a high value.

On the other hand, the fusible current-carrying element (3) gradually increases commutation current I
Due to the Joule loss caused by B, heat is generated, and the temperature reaches time t.
When it reaches the melting point at 2, it melts and generates a high voltage arc with the help of the surrounding buffer (4) and high pressure vessel (5). When this arc voltage reaches the circuit voltage vs of the peak in FIG. 2 at time t3, the current IB and therefore the circuit current 2 become zero and the circuit is cut off.

Since this conventional method performs the above-mentioned breaking operation, the fusible current-carrying element (3) is cut off after the dielectric strength of the electrode (2) is restored as described above. is a requirement for a shutoff, and if this is not met, the arc voltage generated in the high voltage generating part B will cause re-ignition in the electrode (2), leading to failure of commutation, and there is a risk that it will not be possible to shut off. is large. By the way, in this method, Fig. 2(b).

As described above in (c), there is a period in which the current gradually increases until the commutation to the fusible energizing element (3) is completed. Therefore, if the thickness of the fusible current-carrying element (3) is selected so that fusing occurs only after recovery of the dielectric strength in the electrode (2) in response to the current after completion of commutation, from the start of commutation to the completion of commutation. The temperature of the fusible current-carrying element (3) rises due to the current in the electrode (2), and the melting element (3) is blown out before the dielectric strength of the electrode (2) is recovered, so that the requirements may not be met. Therefore, the thickness of the fusible current-carrying element (3) is increased in consideration of the temperature rise due to the current at the point where commutation is completed.

However, in this case, the fusible energizing element (3) inserted between the electrodes (2)
Since the amount of evaporation increases accordingly, the arc voltage generated after fusing decreases, resulting in a decrease in commutation function due to the reverse voltage effect, which is disadvantageous for interrupting. Since the fusible 3-type element (3) is still connected directly to the electrode (2) in parallel, part of the circuit current is always connected to the fusible energized element (3) in inverse proportion to the resistance value of both circuits. This causes the fusible energizing element (3) to generate heat as well. Therefore, since the thickness of the fusible current-carrying element (3) is determined in consideration of this, the thickness has to be further increased, which lowers the arc voltage and reduces the interrupting performance accordingly.

The present invention has been made with the aim of eliminating the above-mentioned drawbacks, and will now be described in detail with reference to the drawings.

The disadvantage of the above conventional method is that there is a period in which the current gradually commutates from the electrode (2) to the fusible current-carrying element (3), which causes the temperature of the fusible current-carrying element (3) to rise due to self-heating effect. This is due to the fact that it has a process of Therefore, in order to eliminate the drawbacks based on this, if the current flowing through the electrode (2) is instantaneously commutated to the circuit of the fusible current-carrying element (3), the thickness of the fusible current-carrying element (3) It is no longer necessary to determine the current in the process up to the completion of commutation, and the time from commutation to fusing is longer than the time from the extinction of the arc at the electrode (2) to the recovery of dielectric strength. What is necessary is to select the thickness of the fusible current-carrying element (3) with respect to the commutation current.

The present invention is based on the above idea and is characterized by the following points. That is, as shown in the circuit diagram of an embodiment shown in FIG. 3 (the same symbols as in FIG. 1 indicate the same parts), a voltage exceeding a specific operating voltage is applied in series with the fusible current-carrying element (3). For example, a gap (6) is connected to the cutting current-carrying part C, which has the function of suddenly applying current only when Turn on the electricity,
Further, the operating voltage is set to sufficiently exceed the value of [resistance R of fusible current-carrying element (3) x circuit current IB + terminal voltage after conduction of cut-off current-carrying portion C].

In this way, the electrode (2) at time to in FIG.
When the arc voltage due to the start of electrode opening exceeds the operating voltage VIC of the gap (6) at time tic and energization is performed, the current flowing through the electrode (2) as shown in FIG. 4(b) becomes zero, and commutation is instantaneously completed in the circuit of the fusible energizing element (3) as shown in FIG. 4(C). Then, the fusible current-carrying element (3) is fused at time t2, and the arc voltage appearing at the fused portion is increased at time t3 as shown in FIG.
When the circuit voltage Vs is reached as shown in d), the current 1B, and thus the circuit current ■, is cut off as shown in FIG. 4(a).

As described above, in the present invention, there is no process in which the commutation current gradually increases as in the conventional method, and moreover, the circuit of the fusible current-carrying element (3) is normally closed due to the non-conducting gap (6). Since the parallel connection relationship with the electrode (2) is broken, a part of the circuit current (2) will not flow as described above and a temperature rise due to self-heating effect will not occur.

Therefore, in consideration of the process up to the completion of commutation and the temperature rise due to part of the circuit current, as in the past, the fusible current-carrying element (3)
The thickness of the fusible current-carrying element (3) is determined for the current IB after completion of commutation so that there is no need to determine the thickness of the electrode (2), and fusing occurs after recovery of the dielectric strength in the electrode (2). do it. As a result, unlike the conventional method, one fusible current-carrying element (three
), it is no longer necessary to make the electrode (2) thicker, and the drop in arc voltage is reduced accordingly.
This ensures the commutation of current to and improves the shutoff performance, eliminating the drawbacks of the conventional method.

The present invention has been explained above using one embodiment, but the gap (
6) In place of ``C'', use a current-carrying part C such as a Zener diode.
can be used. If the electromagnetic energy of the circuit is large, a nonlinear resistor such as a zinc oxide arrester may be connected in parallel to the energy absorbing portion D1, as shown by the dotted line in FIG.

As is clear from the above description, according to the present invention, a high voltage generating section using a fusible current-carrying element is connected in parallel to a current-carrying disconnecting section, and the current in the current-carrying disconnecting section is commutated to the high-voltage generating section to perform the interruption. This improves the breaking performance of power circuit breakers, making it easier to break DC circuits in particular, and has great practical effects.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional circuit breaker, Fig. 2 is a time characteristic diagram of current and terminal voltage of a normal breaker to explain its operation, and Fig. 3
The figure is a circuit diagram of one embodiment of the present invention, and FIG. 4 is a time characteristic diagram of the current of the circuit breaker and the voltage at one terminal to explain its operation. A. Current-carrying disconnection section, S. Opening command, (1). Circuit, (2)
...electrode, B...high voltage generating part, (3)...fusible energizing element, (4)...insulating buffer material (arc extinguishing material), (5)...
・・High-pressure pressure vessel, C... Political power supply section, (6)...
・Gi Young. Patent applicant: Central Research Institute of Electric Power Industry, Researcher: Inuzuka, 1 external person: 8-

Claims (1)

[Claims] A high-voltage generating section in which a fusible current-carrying element is sealed in a high pressure vessel is connected in parallel with the current-carrying disconnection section, and the flowing current of the current-carrying disconnection circuit is generated as a high voltage by the arc voltage caused by the opening of the current-carrying disconnection section. This causes the fusible current-carrying element of the high voltage generating part to melt, thereby generating an arc voltage large enough to interrupt the commutation current due to the reverse voltage action on the circuit voltage. In this type of power circuit breaker, a cutting current-carrying part, such as a gap, which conducts only when the terminal voltage of the current-carrying and disconnecting part is above a certain value, is connected in series with the high-voltage generating part, and the current is passed from the current-carrying disconnecting part to the high voltage. A power circuit breaker characterized by instantaneous commutation of current to the generating part.