JPS58119120A - Dc 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 DC breaker, and more particularly to a DC breaker that cuts off a high frequency current by flowing it through a breaker part through a contact.

Unlike alternating current, direct current does not have a naturally occurring current zero point, so in order to cut it off, special measures must be taken to generate a current zero point, as described below. In other words, the conventional DC breaker has a breaker section 1, as shown in FIG.
It is composed of a capacitor 2, a reactor 3, a contact 4, a circuit resistor 5, etc., among which the capacitor 2, reactor 3, circuit resistor 5, and contact 4 constitute a series connection body, and this series connection The body is connected in parallel to the breaker 1. The breaker 1 is connected in series to a DC power transmission line 6, and the capacitor 2 is constantly charged with the voltage of the DC power transmission line 6 via a charging resistor 7. In the DC breaker configured in this way, when the breaker 1 is opened and the contact 4 is closed at the time of breaker, the capacitor 2
The electric charge is discharged, and a high frequency current, that is, an oscillating current consisting of the capacitor 2, reactor 3, and circuit resistor 5 is generated, and this oscillating current is superimposed on the DC current flowing through the breaker 1 to generate a current zero point. Then, the current slope d of the oscillating current of the lever
If 1/dt is less than the breaking performance limit of the breaking section 1, the breaking current of the DC power transmission line 6 is cut off.

By the way, the waveform of the oscillating current flowing through the breaker 1 attenuates over time, as shown in Figure 3, where the horizontal axis shows time and the vertical axis shows the cutoff current. The current that is cut off for the oscillating current 9 is
When the current zero point is large as in Both are relatively small and can be shut off. On the other hand, when the current to be cut off is small like I2, the number of times the current zero point occurs is greater than when the cut off current is large like I2, as shown in the figure. The initial current zero point 12. increases much more.
The current slope di/dt at 13 is large, and it takes a long time for the current zero point 14.15 to occur at which the current slope di/dt becomes sufficiently small so that the arc can be extinguished at the breaker. are doing.

Therefore, in such a DC breaker, if the circuit constants are determined so as to be able to cut off a large current, the arcing time will become significantly longer in the case of a small current cutoff. The longer the arc time, the more the contact at the breaker will wear out.
The longer the shutoff time is, the more the power is consumed. In particular, when the power source is nuclear power, a short power outage time is required, so the long cut-off time is a serious drawback. Since there is a limit to the time during which the medium is sprayed, that is, the time during which the breaker has the ability to extinguish the arc, the long time it takes for the current zero point to reach the current slope di/dt that allows for breaker to occur means that breaker is not possible. This will cause

The present invention has been made in view of the above points, and its purpose is to provide a DC breaker that can cut off the current reliably regardless of the type of the cutoff part or the magnitude of the current to be cut off. .

That is, the present invention is characterized in that the contact is provided with a closing means that changes the closing timing depending on the magnitude of the current to be cut off.

The present invention will be explained below based on the illustrated embodiments. FIG. 2 shows an embodiment of the invention. Note that parts that are the same as those in the conventional model are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, the contact 4a is provided with a closing means 8 that changes the timing of closing depending on the magnitude of the current to be cut off. The input means 8 is a current transformer 8a provided on the DC transmission line 6,
The timing of turning on is controlled depending on the magnitude of the current that is connected to this current transformer 8a and flows through the DC power transmission line 6 to be cut off.

It was formed from a control device 8b that controls. In other words, the timing of turning on the contact 4a that allows high frequency current to flow through the breaker 1 is changed depending on the magnitude of the current that is cut off by the current transformer 8a and the control device 8b. By doing this,
The contact 4 is made in accordance with the magnitude of the current cut off by the current transformer Ba and the control device 8b, and the breaker 1 is able to break when the arc extinguishing ability of the breaker 1 is below the limit (within a time range). It becomes possible to generate a current zero point with a current slope di/dt, and the interruption is reliably performed regardless of the type of the interruption part or the magnitude of the current to be interrupted.

As shown in Figure 4, the vertical axis shows the current L, which is cut off, and the horizontal axis shows the time, which is the oscillating current 16 when the cutoff current is small at I2 (indicated by a solid line in the figure). ,
This is also clear from the current waveform characteristics of the oscillating current 17 (indicated by the dotted line in the figure) when the cutoff current is large. That is, in the figure, tl is the time from when the breaker opens to when the breaker starts to have arc-extinguishing ability, and tl is the time until the breaker finishes having arc-extinguishing ability. t
, ~t2 is the time period from when the breaker is opened to when the breaker has the interrupting ability. The time from the generation of the oscillating current to the occurrence of a current zero point with a current slope di/dt that can be cut off is t in both cases where the cutoff current is large and small. It is only necessary to allow a time t3 until a current zero point that can be cut off occurs between the time t and t2 when the device has arc extinguishing ability, and for that purpose, the contact is turned on from the opening of the breaker part and the vibration is applied. The time required for the current 16.17 to flow is defined as the time t1 until the breaker starts to have arc-extinguishing ability, the time t2 until the breaker finishes having arc-extinguishing ability, and the time until the breaker generates a current zero point that can be cut off. time 1 after subtracting time t, respectively
．． -1° and 1. -13.

In this way, regardless of the size of the current that is cut off,
This is because a current slope di/dt7)+ or a current zero point having a magnitude that allows the arc to be cut off always occurs within the time period in which the breaker has the arc extinguishing ability. Therefore, if the current to be cut off is small like I2 and it takes a long time to generate a current zero point that can be cut off, that is, if the time t3 until the current zero point that can be cut off is large, the oscillating current 16, when the contact is turned on early, the current to be cut off is large, and the current zero point that can be cut off occurs in a short time, t is small, the oscillating current 1
It is sufficient to delay the closing timing of the contact as shown in 7.

As described above, the present invention allows a high-frequency current to flow by changing the timing of turning on the contact depending on the magnitude of the current to be cut off. Regardless of the type, it can now be generated within the time that the breaker has the arc extinguishing ability.
It is possible to obtain a DC breaker which can ensure reliable interruption of the interruption current regardless of the type of the interruption part or the magnitude of the current to be interrupted.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional DC breaker, Fig. 2 is a circuit diagram of an embodiment of the DC breaker of the present invention, Fig. 3 is a waveform diagram of high frequency current of a conventional DC breaker, and Fig. 4 1 is a waveform chart of high-frequency current when the timing of turning on is changed in one embodiment of the DC breaker of the present invention. DESCRIPTION OF SYMBOLS 1... Breaking part, 2... Capacitor, 3... Reactor, 4a... Contact, 6... DC transmission line, 8...
...Inserting means, 8a...Current transformer, 8b...Control device, 16.17...High (1 other person) Fig. 1 8m

Claims (1)

[Scope of Claims] 1. A power supply system comprising a breaker provided in a DC transmission line, and a series connection body of a capacitor and a reactor connected in parallel to the breaker via a contact, and when the breaker is opened,
In the direct current breaker, which cuts off the current by turning on the contact and causing a high frequency current to flow from the series connection body to the breaking section, the timing of turning on the contact is changed depending on the magnitude of the current to be cut off. A DC breaker characterized by being provided with a charging means. 2. The closing means controls the closing timing according to a current transformer provided on the DC power transmission line and the magnitude of the current to be cut off that is connected to the current transformer and flows through the DC transmission line. The primary breaker according to claim 1, which is formed from a control device.