JPH0687388B2 - DC circuit breaker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a DC circuit breaker.

[Conventional technology]

It is a well-known fact that a DC circuit breaker has been put into practical use for DC power transmission and for plasma heating equipment for nuclear fusion (for example, published in the September 1980 issue of Electrical Review).

By the way, conventionally, the operating device for operating the DC breaker is one set per DC breaker (one set per switching contact).
Group).

[Problems to be solved by the invention]

In the above-mentioned conventional technique, it takes a long time from when the DC circuit breaker is given an opening command until the contacts are actually opened. Therefore, when the DC circuit breaker is applied as a load switch, there is no problem, but when it is applied for circuit protection which is responsible for interrupting the accident current, the following problems occur when the contacts are opened.
That is, when the contacts are opened, the Electrical Standards Committee standard (DC high-speed circuit breaker for electric railway substations) (JEC-15
2) Calculating using the specified current charge rate of 3 × 10 ⁶ (A / S), after reaching the standard maximum value of estimated short circuit current of 50 kA,
As a result, the capacitor capacity of the commutation circuit required to form the current zero has to be increased according to the magnitude of the short circuit current.

In addition, it is not advisable to increase the operating force because the opening time is shortened or to adopt a high-speed operating device such as a hydraulic operating device or an electromagnetic repulsive operating device, as described below. That is, if the possibility of interrupting the fault current and the load switching frequency are compared, the frequency is high enough to call the load switching almost. Therefore, the operating force necessary for interrupting an accident current that occurs extremely rarely is sufficient to cut off the load current on a daily basis with a light operating force, which is not a good idea in terms of switching life.

The present invention has been made in view of the above points, and an object of the present invention is to provide a DC circuit breaker capable of reducing the capacitance of a capacitor.

[Means for solving problems]

The above-mentioned object is to cut off the accident current by using a high-speed operating device such as a hydraulic operating device or an electromagnetic repulsion coil that operates at high speed, and cut off the load current by using a low-speed AC5 cycle circuit breaker commonly used. It is achieved by using a normal operation device that operates in accordance with (1) and determining those selections based on the operation of the accident detection relay.

[Action]

In case of accident current interruption, the accident detection relay detects the accident,
Give operation commands to the high speed controller. In this case, the closing switch provided in the commutation circuit is closed at the same time or in synchronization with the opening of the contact. As a result, the contacts are opened in the process of increasing the fault current, and the fault current is interrupted when the zero point is formed in the fault current by the high-frequency reverse current applied from the commutation circuit.

In the case of normal load current interruption, the normal operation device is operated by the closing command, and the closing switch of the reverse current circuit is closed in synchronization with the contact opening. As a result, the load current is interrupted when the zero point is formed in the load current by the high-frequency reverse current applied from the commutation circuit.

In this way, in the case of fault current interruption, it is necessary to adjust the capacity of the capacitor to the standard maximum value of the fault current (short circuit current) so that it can be interrupted during the rising process, and the capacity of the capacitor can be reduced. .

〔Example〕

Hereinafter, the present invention will be described based on the illustrated embodiments. FIG. 1 shows an embodiment of the present invention. As shown in the figure, the DC circuit breaker has a main circuit 1A having a contact 2 provided between the main circuit conductors 1a and 1b, and a contact 2 of this main circuit 1A.
Is equipped with a commutation circuit 5A which is connected in parallel via a closing switch 3 and in which a capacitor 4 and a reactor 5 are connected in series. Then, when the contact 2 is opened, the closing switch 3 is closed to flow a high frequency current from the commutation circuit 5A to the contact 2 to cut off the interrupted current.

With the DC circuit breaker configured as described above, the contact 2 is used in this embodiment.
In addition, when the accident current is cut off, the contact 2 can be opened at a higher speed and faster than when the load current is cut off.
When the load current is cut off, the contact 2 can be opened at a slower speed, which is slower than that when the accident current is cut off.
Is provided so that both operation devices 6 and 7 can be selectively operated. By doing so, the contact 2 has a high-speed operating device 6 capable of opening the contact 2 at a high speed faster than that at the time of load current interruption at the time of interruption of the accident current, and the contact 2 at the time of interruption of the fault current at the time of load current interruption. A normal operation device 7 is provided, which is slower than that at the time of shutting off and can be opened at a constant speed,
Both of these operating devices 6 and 7 can be selectively operated, and it becomes possible to interrupt the fault current in the rising process,
It is possible to obtain a DC circuit breaker capable of reducing the capacity of the capacitor 4.

That is, during operation, the main circuit conductor 1a and the contact 2 in the vacuum container 8
And a current flows through the main circuit conductor 1b as a path. In this case, the closing switch 3 is opened, and the commutation capacitor 4 is constantly charged by the charger 9.

When a fault current flows in the main circuit 1A composed of the main circuit conductor 1a, the contact 2, the main circuit conductor 1b, etc., an abnormality is detected by an overcurrent relay (not shown) and a signal is sent to the control device 10. . The controller 10 determines that the fault current has been cut off, and gives an operation command to the high-speed operating device 6 and the closing switch 3 to cut off the current. In this case, synchronization between the contact opening time of the contact 2 by the high-speed operation device 6 and the time until the current zero point is generated by the commutation circuit 5A formed by the condenser 4 and the reactor 5 formed by the closing circuit of the closing switch 3 is It is taken by the controller 10 as needed.

In the case of load current interruption, a control device that receives a trip control command
It is determined that 10 is the load current interruption, and an operation command is given to the normal operation device 7 and the closing switch 3 to interrupt the current.
The opening time of the contact 2 by the normal operation device 7 and the time until the current zero point occurs by the commutation circuit 5A are determined by the controller 10 by setting the operation command time to the normal operation device 7 and the closing switch 3 separately. Synchronize.

FIGS. 2A and 2B show the relationship between the breaking current and the time, with the vertical axis representing current and the horizontal axis representing time. In the figure, B is an accident occurrence, C is a relay time, D is an opening time, E is a commutation start, F is a cutoff completion, and G is a cutoff command. In the case of the fault current interruption, as is clear from FIG. 7A, when the interruption command G is given after the relay time C at the accident occurrence B, the commutation start E is performed during the opening time D, and the fault current Shutdown complete F during ascending.

In the case of load current interruption, as is clear from FIG.
Commutation start E is performed during the opening time D by the shutoff command G,
Although the cutoff completion is F, the time for the cutoff completion F is longer than that of the above-mentioned fault current.

In this way, the interruption can be completed while the fault current is rising.
As is clear from the figure, since the vacuum interrupter in which the contact 2 is housed in the vacuum container 8 is used, the frequency of the commutation circuit 5A can be increased by making use of the excellent high-frequency cutoff performance of the vacuum interrupter. Therefore, the current zero point can be quickly formed, and the capacity of the capacitor 4 can be reduced as compared with the case where the contact 2 is not housed in the vacuum container 8.

Further, the high-speed operating device 6 drives the lower electrode 2a of the contact 2 downward in the vacuum interrupter, and the normal operating device 7 drives the upper electrode 2b of the contact 2 upward, so that the contact 2
And the connection structure between the respective operation devices 6 and 7 can be simplified.

As described above, according to the present embodiment, it is necessary to shorten the contact opening time and to enhance the driving force for the fault current interruption, and to reduce the driving force for extending the life in the load interruption requiring the frequent switching performance. By designing the actuator for fault current interruption and load current interruption under the contradictory conditions, it is possible to design and manufacture according to each condition. Therefore, in the fault current interruption, the contact opening time can be shortened without considering the durability against the frequent operation, and the capacitor capacity can be reduced. In the load current interruption, the load of the normal operation device can be reduced without considering the accident current interruption, so that the switching life can be extended.

In addition, when the accident current is cut off, two sets of operating devices, a high-speed operating device and a normal operating device, are operated, that is, after the current is cut off by the high-speed operating device, the operation of the normal operating device that has opened with a time delay is completed. By resetting the open state of the high-speed actuator, the main circuit reclosing operation can be performed only by the normal actuator, so it is not necessary to provide the high-speed actuator with the closing capacity.
The structure can be simplified.

〔The invention's effect〕

As described above, according to the present invention, the capacity of the capacitor can be reduced, and a DC circuit breaker that can reduce the capacity of the capacitor can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a DC circuit breaker of the present invention,
FIGS. 2 (a) and 2 (b) similarly show the relationship between the breaking current and the time in one embodiment. FIG. 2 (a) is a characteristic diagram in the case of fault current interruption, and (b) is a characteristic diagram in the case of load current interruption. Is. 1A ... Main circuit, 1a, 1b ... Main circuit conductor, 2 ... Contact, 2a
...... Lower electrode, 2b ...... Upper electrode, 3 …… Mixing switch,
4 ... Capacitor, 5 ... Reactor, 5A ... Commutation circuit, 6 ... High speed operation device, 7 ... Normal operation device, 8 ... Vacuum container, 9 ... Charger, 10 ... Control device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masafumi Oshima 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubun Factory, Hitachi Ltd. (72) Hideaki Tsuda 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Kokubun Plant of Hitachi, Ltd. (72) Inventor Motoo Sato 1-1-1 Kokubuncho, Hitachi City, Ibaraki Inside the Kokubun Plant of Hitachi Ltd.

Claims (2)

[Claims] 1. A main circuit having at least one contact provided between main circuit conductors, and a parallel connection to the contact of the main circuit via a closing switch, and a capacitor and a reactor connected in series. A direct current circuit breaker, which comprises a commutation circuit and which closes the contact by opening the closing switch to flow a high-frequency current from the commutation circuit to the contact to break the current that is interrupted. A high-speed operating device that can open the contact at high speed at a faster speed than the load current at a current interruption, and at a lower speed at a lower speed than the contact at fault current interruption at a load current interruption. A direct-current circuit breaker characterized by being provided with a normal operating device capable of performing such operation and selectively operating both of these operating devices. 2. The DC circuit breaker according to claim 1, wherein both the high-speed operation device and the normal operation device are made to operate when the fault current is cut off.