JPH03276527A - Dc breaker - Google Patents

Abstract

PURPOSE:To improve current breaking performance with a current rate of change of breaking current restrained with simple constitution by surroundedly providing a magnetic substance, saturated with a given current larger than rated current, on a main circuit to which a main contact is connected. CONSTITUTION:A magnetic substance 20, which is on a disc and composed by laminating thin iron plates, is surroundedly provided on the outer periphery of a conductor 11 in a vacuum vessel consisting of an insulating tube 12, fixed side plate 13, and movable side plate 14, etc., and also is supported and fixed in the inner surface of the insulating tube 12. In the same way, a disc-like magnetic substance 21, composed by laminating thin iron plates, is surroundedly provided on the outer periphery of a conductor 17 in the vacuum vessel, and also is supported and fixed in the inner surface of the insulating tube 12. Moreover both the magnetic substances 20 and 21 have constitution in which they are saturated at a given current value larger than rated current. By this, when short-circuit current exceeding rated current flows in a main contact 1, the magnetic substances 20 and 21 are saturated to restrain the rate of change of current flowing in the main contact 1, therefore current breaking is eased, and a DC breaker having simple constitution as a whole is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a DC circuit breaker, and particularly to a DC circuit breaker in which a commutation circuit consisting of a capacitor, a reactor, and a switch connected in series is connected in parallel with a main circuit breaker. Regarding current type DC circuit breakers.

[Prior Art] A conventional DC breaker of this type is disclosed in, for example, Japanese Patent Application Laid-Open No. 54-14
It is published in the No. 0176 publication, and its circuit diagram is shown in FIG. That is, a saturation reactor 2 is connected in series with the main contact l, and a capacitor 5. It is constructed by connecting a commutation circuit consisting of a reactor 4 and a switch 3 to an energy absorbing device 6.

In a DC breaker with such a configuration, a short circuit current i is applied to the main contact 1.
5, this short circuit current i is detected by a current detector (not shown) and opens the main contact l at time t, and closes the switch 3 at time t. Then, the capacitor 5 is discharged, and the currents generated by the capacitor 5 and the reactor 4 flow in a superimposed manner to the main contact l. If there is no saturation reactor 2, the current flowing through the main contact 1 will flow as a high-frequency oscillating current I, as shown by the dotted line in Figure 2, but if there is a saturation reactor 2, the current will flow as a high-frequency oscillating current I, as shown by the solid line in Figure 2. The current change rate d i / dL becomes a relaxed current I, and di / d t near the current zero point is suppressed to a sufficiently smaller value in the latter case than in the former case, making it easy to interrupt the current at the main contact 1. can.

In addition, a vacuum circuit breaker is generally used for the above-mentioned main contact l, and in this vacuum circuit breaker,
As described in the above publication, it is known that the interrupting performance can be improved by applying a magnetic field parallel to the arc generated between the electrodes when the current is interrupted.

[Problem to be solved by the invention]

As mentioned above, in the conventional DC circuit breaker, by connecting the winding saturation reactor 2 in series with the main contact l, it was possible to suppress the current change rate di/dt and facilitate current interruption. Considering the saturation reactor 2 in which a current of several thousand amperes flows continuously, the reactor becomes extremely large and is not practical.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC breaker that has a simple configuration, suppresses the rate of change in current, and facilitates current interruption.

[Means for Solving the Problems J] In order to achieve the above object, the present invention is provided with a magnetic material that surrounds a main circuit through which a rated current flows, and that saturates at a predetermined current value larger than the rated current. It is characterized by:

[Effect]

Since the DC breaker according to the present invention has the above-mentioned configuration,
When a short circuit current exceeding the rated current flows through the main contacts, the magnetic material becomes saturated.As with conventional saturation reactors, the rate of change in the current flowing through the main contacts is suppressed, making it easy to interrupt the current. Since it does not form a circuit, the DC breaker can have a simple configuration as a whole.

〔Example〕

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

FIG. 3 shows a circuit diagram of a DC breaker according to an embodiment of the present invention. A commutation circuit consisting of a capacitor 5, a reactor 4 and a switch 3 is connected in parallel with the main contact 1, and an energy absorbing device 6 is also connected thereto. However, there is no saturation reactor in series with the main contact 1 shown in FIG.

FIG. 1 shows an example of the detailed structure of the main contact 1, in which the main contact 1 is composed of a vacuum circuit breaker.

The cylindrical insulating tube 12 has an upper end hermetically sealed by a fixed side plate 13, and a lower end hermetically sealed by a movable side plate 14 and a bellows 15. A fixed pole 10 is provided at the lower end of the conductor 11 that passes through the fixed side plate 13 in an airtight manner, and a movable electrode 16 is provided at the upper end of the conductor 17 that passes through the bellows 15 in an airtight manner. The lower end of this conductor is connected to an operating device (not shown).

The above configuration is the same as a normal vacuum circuit breaker.

However, the insulation cylinder 12. Fixed side plate 13 and movable side plate 14
A disc-shaped magnetic body 20 made of laminated thin iron plates is provided surrounding the outer periphery of the conductor 11 in a vacuum vessel made of a conductor 11, and is supported and fixed on the inner surface of an insulating cylinder 12. Similarly, a disk-shaped magnetic material 21 made of laminated thin iron plates is provided surrounding the outer periphery of the conductor 17 in the vacuum vessel, and a magnetic material 21 is provided surrounding the conductor 17 and is supported and fixed on the inner surface of the insulating tube 12. Looking at the outside of the vacuum container, at the outer peripheral ends of both magnetic bodies 20 and 21,
A substantially cylindrical iron core 22 with its upper and lower ends facing each other is provided, and a conductor 23 is provided on the inner or outer circumferential side of this iron core 22.
is wound around the conductor 23, and a power source that supplies direct current to the conductor 23 is not shown, but it is configured to supply current to the conductor 23 in conjunction with the opening and closing of the switch 3 in FIG. 3, for example. .

Although the magnetic bodies 20 and 21 described above can be configured outside the vacuum container, they are configured integrally with the 5 vacuum circuit breaker in order to downsize the DC circuit breaker as a whole.

Since the magnetic bodies 20 and 21 are made of iron, if they are simply placed in a vacuum vessel, the degree of vacuum will be affected by oxygen trapped inside due to oxidation on the surface. Therefore, the magnetic bodies 20 and 21 are pickled and nickel-plated or copper-plated before being assembled into the vacuum container.

These surfaces are dense and do not allow gas to penetrate inside, so after placing them in a vacuum container and drawing a vacuum, the main contacts 1 with such a structure will not reduce the degree of vacuum, as shown in Figure 3. Now,
It is assumed that a short circuit current flows through the main circuit when the fixed electrode 10 and the movable electrode 16 are in contact with each other. This current is detected by a detection device (not shown) as in the conventional case, and is passed through the conductor 17 to the movable I
f! 16 in the downward opening direction and the switch 3
Close. At this time, the capacitor 5 is discharged and a high frequency current due to resonance is superimposed between the fixed current 10 and the movable current 116,
Further, a magnetic field is generated in the magnetic bodies 20 and 21 as shown in FIG. Although these magnetic bodies 20 and 21 are not saturated at the rated current,
For example, since the structure is such that it is saturated when a predetermined current of about 1.5 to 2 times the rated current flows, the rate of change of the current flowing between the electrodes 10 and 16, d i / d t, is as shown in the current ■ in Fig. 5. suppressed. Furthermore, if a direct current is passed through the conductor 23 at this point, a parallel magnetic field can be generated between the electrodes 10.16 like the magnetic flux Φ due to the action of the iron core 22 and the magnetic body 20.21, and this type of circuit breaker As is known, the interrupting performance can be improved by using a magnetic field parallel to the current direction.

The magnetic bodies 20 and 21 in the above-described embodiments may be provided outside the vacuum container, and may also be applied to main contacts 1 other than vacuum circuit breakers; In this case, as shown in FIG. 1, magnetic bodies 20 and 21 are placed inside the vacuum container so that they work together with the iron core 22, thereby making the entire structure compact.

〔Effect of the invention〕

As explained above, the present invention has a main circuit connected to the main contacts surrounded by a magnetic material that saturates at a predetermined current larger than the rated current. The configuration can suppress the current change rate of the interrupting current and improve current interrupting performance.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a specific configuration of the main contact of a DC breaker according to an embodiment of the present invention, FIG. 2 is a magnetic circuit diagram showing the main part of FIG. 1, and FIG. A circuit diagram of a DC breaker according to an embodiment, FIG. 4 is a circuit diagram of a conventional DC breaker, and FIG. 5 is a circuit diagram of a conventional DC breaker.
The figure is a waveform diagram of the breaking current. l...Main contact, 3...Switch, 4.
...Reactor, S ... Capacitor, 6
... Energy absorption device, 10 ... Fixed electrode, 16 ... Movable electrode, 20.21 ...
...Magnetic material, 22...Iron core, 23...
conductor. I7: Conductor B, 21. 22, No. 7 (23)

Claims (1)

[Claims] 1. A DC circuit breaker comprising a commutation circuit in which a capacitor, a reactor, and a switch are connected in series, and an energy absorption device are connected in parallel to a main contact, in which the main contact is provided. 1. A DC circuit breaker comprising a magnetic material that surrounds a conductor of the circuit and saturates when the current flowing through the main circuit reaches a predetermined value. 2. The vacuum circuit breaker according to claim 1, wherein the main contact has a fixed electrode and a movable electrode arranged inside the vacuum vessel, and a conductor supporting each of these electrodes and leading out of the vacuum vessel. A DC circuit breaker characterized in that the magnetic material is provided to surround the conductor in the vacuum container. 3. The DC circuit breaker according to claim 2, wherein the magnetic body is coated with either nickel plating or copper plating to form a rust-preventive coating. 4. In the device according to claim 2, the magnetic body is provided to surround both the conductors, and an iron core having both ends facing the pair of magnetic bodies is provided outside the vacuum container, and a winding is wound around the core. A DC circuit breaker characterized by comprising a conductor that is turned and connected to a DC power source.