JPH0737471A - Commutation type d.c. circuit breaker - Google Patents

Abstract

PURPOSE:To provide a commutation type d.c. circuit breaker, by which matching of the action timing between a main contact point and an instantaneous contact switch is facilitated, and which has a stable circuit breaking performance. CONSTITUTION:An electromagnetic repulsion coil 5 is provided in the vicinity of a short ring 7 connected to the moving electrode 1B of a main contact 1. The electromagnetic repulsion coil 5 is connected to a commutation circuit 6, and the electromagnetic repulsion coil 5 is magnetized by the discharge current I2 of a capacitor 4 run by closing the instantaneous switch 3 of the commutation circuit 6, to provide operation force for closing the main contact 1. The discharge current I2 running reverse to a main circuit current I1 is fed to the main contact point 1, to form a current zero point on the main circuit current I1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a commutation type DC circuit breaker in which a series connection instantaneous switch and a capacitor are electrically connected in parallel with a main contact.

[0002]

2. Description of the Related Art As a conventional commutation type DC circuit breaker, the one described in Japanese Patent Laid-Open No. 54-140176 is known, which is shown in FIG. The momentary contact switch S2, the capacitor C1 and the reactor L1 connected in series are connected to each other with the main contact S1.
When the current is cut off, the main contact S1 is first opened, and immediately after the main contact S1 is opened, the instantaneous switch S2 is closed to prevent the main circuit current I1 from flowing in the opposite direction. The discharge current I2 of the capacitor C1 is caused to flow to the main contact S1,
As a result, a current zero point is created at the forced point in the main circuit current I1, and the current is cut off at the main contact S1.

[0003]

As described above, in the commutation type DC circuit breaker, the discharge current I2 of the capacitor C1 is increased.
The discharge current of the capacitor C1 is short, so the timing of opening the main contact S1 and closing the circuit of the instantaneous contact switch S2 is short. If they do not match, it will be impossible to shut off. For example, as shown in FIG. 2, the occurrence of an accident at time T1 is detected, the main contact S1 is opened, and then the time T1 is reached.
If the instantaneous switch S2 is closed as shown in A in FIG. 2, even if a current zero occurs, the interelectrode gap of the main contact S1 is not opened by a size required for insulation recovery, so that it cannot withstand voltage and cannot be interrupted. On the other hand, if the momentary switch S2 is closed at time T3 as shown by B, the closing timing of the momentary contact switch S2 is delayed, and the current value of the main circuit becomes larger than the discharge current value of the capacitor, so that the current zero point cannot be created. Will end up. In order to obtain a good breaking performance even in the former timing, for example, the vacuum degree of the vacuum valve forming the main contact S1 may be increased, but on the other hand, the life of the vacuum valve becomes a problem, and in the latter timing, it is also preferable. In order to obtain the breaking performance, for example, the capacity of the commutation capacitor C1 may be increased, but the commutation capacitor becomes large.

Therefore, it is necessary to adjust the operation timings of the main contact S1 and the instantaneous contact switch S2 in a predetermined relationship.
However, in the above-mentioned conventional commutation type DC circuit breaker, a drive device that generates an operation force that opens the main contact S1 and a drive device that generates an operation force that closes the instantaneous switch S2 are separately configured. Therefore, the variation in the operating time in the electric system of each drive device can be suppressed to a negligible amount, while the variation in the operating time in the mechanical system of each drive device is large, and eventually the main contact S1 and It was difficult to adjust the operation timing with the instantaneous contact switch S2 to a predetermined relationship.

It is an object of the present invention to provide a commutation type DC circuit breaker in which the operation timings of the main contact and the instantaneous contact switch can be easily adjusted and which has stable breaking performance.

[0006]

In order to achieve the above object, the present invention connects a commutation circuit in which an instantaneous switch and a capacitor are connected in series to a main contact of a DC main circuit in parallel,
An electromagnetic repulsive body connected to the movable electrode of the main contact is given an electromagnetic repulsive force to open the electrode, and the discharge current of the capacitor is supplied to the main contact to create a current zero point in the main circuit current of the DC main circuit. In such a commutation type DC circuit breaker, an electromagnetic repulsion coil is provided so as to face the electromagnetic repulsion body, and the electromagnetic repulsion coil is connected in series with the instantaneous switch and the capacitor.

[0007]

In the commutation type DC circuit breaker according to the present invention, the instantaneous contact switch, the capacitor and the electromagnetic repulsion coil are connected in series as described above. Since the main contact can be opened by exciting the electromagnetic repulsion coil, it is easy to match the operation timing of the main contact and the momentary contact switch, and the momentary switch and the main contact can be synchronized in a nearly constant relationship. Stable interruption performance can be obtained.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a commutation type DC circuit breaker according to an embodiment of the present invention, which is constructed by connecting a commutation circuit 6 to a DC main circuit 2 in electrical parallel. The main contact 1 provided in the DC main circuit 2 is a vacuum valve having a fixed electrode 1A and a movable electrode 1B, and an electromagnetic repulsive body such as a short ring 7 is connected to the movable electrode 1B. The electromagnetic repulsion coil 5 is arranged close to the first side in an electrically insulated state. The commutation circuit 6 is configured by connecting the instantaneous contact switch 3, the capacitor 4, and the electromagnetic repulsion coil 5 in electrical series.

Next, current interruption in the commutation type DC circuit breaker having the above-mentioned configuration will be described with reference to FIGS. 1 and 3. First, as shown in FIG. 3, when an accident occurrence is detected at time T1, the instantaneous contact switch 3 is closed at time T2. Then, the instantaneous contact switch 3 ... capacitor 4 ... shown in Fig. 1
Electromagnetic repulsion coil 5 Main contact 1 Closed circuit of instantaneous contact switch 3 is formed and capacitor 4 is discharged. The discharge flow I2 of the capacitor 4 excites the electromagnetic repulsion coil 5 to generate an electromagnetic repulsion force between it and the short ring 7, whereby the movable electrode 1B of the main contact 1 starts to open and the previous discharge occurs. The flow current Ι2 is the main circuit current Ι with respect to the opened main contact 1.
The current flows in the direction opposite to 1, forcibly creating a current zero point, and the current is cut off.

At this time, the DC main circuit 2 is opened to open the main contact 1.
Since the capacitor 4 connected to is used, a large electromagnetic repulsive force can be obtained, and due to this large electromagnetic repulsive force, the operation from the closing of the instantaneous contact switch 3 to the opening of the main contact 1 varies. It is prevented from occurring. That is, in the conventional configuration, since the capacitors connected to the operating power supply are used for the main contact 1 and the instantaneous contact switch 3, respectively, a large driving force cannot be expected due to the difference in the power supply, and the operation in the mechanical system is not possible. Variation is the main contact 1
However, since the large electromagnetic repulsive force is obtained by using the capacitor 4 connected to the DC main circuit 2 as described above, the variation in the operation timing of the mechanical switch is caused. Will be almost ignored. Therefore, the time from the closing of the instantaneous contact switch 3 to the opening of the main contact 1 is always substantially constant.
Further, since the frequency characteristic of the discharge current I2 determined by the inductance of the capacitor 4 and the electromagnetic repulsion coil 5 is also constant, the relationship between the opening of the main contact 1 and the current zero of the main circuit current I1 is always almost constant and stable. A blocking performance can be obtained. Further, as shown in FIG. 3, since the discharge continuous flow Ι2 of the capacitor 4 is supplied to the main contact 1 prior to the opening of the main contact 1, the main circuit current Ι1 flowing there when the main contact 1 is opened. It has already been attenuated, and the consumption of the electrodes 1A and 1B due to the arc that accompanies the opening of the main contact 1 is suppressed.

Further, in the conventional structure, as shown in FIG. 4, a reactor L dedicated to the electromagnetic repulsion coil 5 is provided separately.
1 was used to determine the frequency characteristics of the discharge current II, but
This reactor L1 is not arranged in the vicinity of the main contact 1 like the electromagnetic repulsion coil 5 shown in FIG. 1, but rather is arranged in the remaining space in the switchboard, so that both ends of the reactor L1 and the capacitor 4 are arranged. The length of the conductor used to electrically connect to and was increased, and the circuit resistance was increased by that amount, and the discharge current I2 was suppressed. However, in this embodiment, as shown in FIG. 1, the electromagnetic repulsion coil 5 is also used as the reactor L1 that determines the frequency characteristics of the discharge current I2, and the electromagnetic repulsion coil 5 is located near the movable electrode 1B of the main contact 1. The length of the conductor used for the electrical connection is shorter than that in the conventional case, and the circuit resistance is reduced by that amount, and the discharge current Ι2 is reduced.
Can be increased to easily obtain the current zero point.
In the above-described embodiment, the inductances of the conventional reactor L1 and the electromagnetic repulsion coil 5 are matched, but the reactor L1 is used for generating the operating force as the electromagnetic repulsion coil 5 and for adjusting the frequency characteristic of the discharge reflow current I2. You may divide and arrange.

FIG. 5 shows a more detailed circuit diagram of the above-mentioned commutation type DC circuit breaker.

The basic structure comprising the main contact 1 provided in the DC main circuit 2, the instantaneous contact switch 3 and the capacitor 4 of the commutation circuit 6 electrically connected in parallel to the DC main circuit 2 is as shown in FIG. Is the same. The instantaneous contact switch 3 is composed of a vacuum valve having a fixed electrode 3A and a movable electrode 3B, and an electromagnetic repulsive body such as a short ring 8 is connected to the movable electrode 3B. The electromagnetic repulsion coil 9 is arranged in this state. A low-voltage capacitor 13 and a thyristor 14 are connected to the electromagnetic repulsion coil 9, and a controller 12 is connected to the current detector 11 provided in the DC main circuit 2, and the thyristor 14 is ignited by the controller 12. The drive device 10 for the instantaneous contact switch 3 is configured as described above.

Now, when the current detector 11 detects a fault current, the control device 12 takes this and gives a closing operation signal to the drive device 10 as an interruption command. Then, the thyristor 14 is ignited and the electromagnetic repulsion coil 9 is excited to generate an electromagnetic repulsion force between the short ring 8 and the short ring 8. This electromagnetic repulsive force drives the short ring 8 to bring the fixed electrode 3A and the movable electrode 3B into contact with each other to close the momentary contact switch 3, and the capacitor 4 ... Electromagnetic repulsion coil 5 ... Main contact 1 ... Instantaneous contact switch 3 The closed circuit is formed, the capacitor 4 discharges and the discharge current I2 is supplied to the electromagnetic repulsion coil 5 and the main contact 1, and the current is cut off as described above. As you can see from this explanation, the instantaneous contact switch 3
Requires a drive unit 10 composed of a low-voltage capacitor 13 and a thyristor 14, etc., whereas the main contact 1 does not require a dedicated drive unit of the same construction, so that the control unit 12
It suffices to control only the drive device 10 for the electromagnetic repulsion coil 9 of the instantaneous contact switch 3, and the configuration can be simplified.

[0016]

As described above, according to the commutation type DC circuit breaker of the present invention, the electromagnetic repulsion coil for driving the main contact is connected to the commutation circuit consisting of the instantaneous contact switch and the capacitor, and the capacitor Since the operating force of the main contact is obtained by exciting with the discharge discharge, the timing for opening the main contact after closing the momentary contact switch can be kept almost constant, and stable breaking performance can be exhibited.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a main part of a commutation type DC circuit breaker according to an embodiment of the present invention.

FIG. 2 is a waveform diagram showing an operation sequence and timing of a main contact and a momentary contact switch in a conventional commutation type DC circuit breaker.

3 is a waveform diagram showing an operation sequence and timing of a main contact and an instantaneous contact switch in the commutation type DC circuit breaker shown in FIG.

FIG. 4 is a circuit diagram of a conventional commutation type DC circuit breaker.

FIG. 5 is a circuit configuration diagram showing details of a commutation type DC circuit breaker according to an embodiment of the present invention.

[Explanation of symbols]

 1 Main Contact 2 DC Main Circuit 3 Instantaneous Contact Switch 4 Capacitor 5 Electromagnetic Repulsion Coil 7 Short Ring 10 Drive Unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Oide 1-1-1 Kokubuncho, Hitachi-shi, Ibaraki Hitachi Kokubun Plant, Ltd.

Claims (3)

[Claims] 1. A commutation circuit, in which an instantaneous switch and a capacitor are connected in series, is connected in parallel to a main contact of a DC main circuit, and an electromagnetic repulsive force is applied to an electromagnetic repulsive body connected to a movable electrode of the main contact to open a pole. In the commutation type DC circuit breaker, in which the discharge current of the capacitor is supplied to the main contact to create a current zero point in the main circuit current of the DC main circuit, the electromagnetic repulsive body is opposed to the electromagnetic repulsive body. Providing a repulsion coil,
A commutation type DC circuit breaker characterized in that the electromagnetic repulsion coil is connected in series with the instantaneous switch and the capacitor. 2. The commutation type DC circuit breaker according to claim 1, wherein the momentary switch is provided with a drive device for closing the circuit in response to a breaking command. 3. A commutation circuit in which an instantaneous switch, a reactor and a capacitor are connected in series is connected in parallel to a main contact of a DC main circuit, and an electromagnetic repulsive force is applied to an electromagnetic repulsion body connected to a movable electrode of the main contact. In a commutation type DC circuit breaker in which the discharge current of the capacitor is supplied to the main contact to create a current zero point in the main circuit current of the DC main circuit, the electromagnetic repulsion that doubles as the reactor is used. A commutation type DC circuit breaker, wherein a coil is provided so as to face the electromagnetic repulsion body, and the electromagnetic repulsion coil is connected in series with the instantaneous switch and the capacitor.