JPH05266768A - D.c. breaker - Google Patents

Abstract

PURPOSE:To improve breaking performance with an insulation recovering characteristic after current breaking improved, and with the diffusion of charged particles in a radical direction undisturbed, by making a current-zero point at a point of time when axial magnetic flux is sufficiently attenuated. CONSTITUTION:Commutation capacitors 5a and 5b are charged previously. Excess current, flowing in a main circuit, is detected with an excess current trip device 7, and an axial magnetic field, generated by an electrode itself, is applied to arcs generated by separating a movable electrode 2b from a fixed electrode 2a. At the time of breaking, first, a trigger gap 8a is ignited, and first current is applied to reduce the absolute value of current flowing in a main electrode. A trigger gap 8b is ignited so as to make a current-zero point at a point of time, when axial magnetic flux is sufficiently attenuated behind a change of current, and then second current is applied to make a current-zero point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC circuit breaker using a vacuum valve, that is, a DC circuit breaker used to protect a circuit when a DC current exceeding a specified value flows through the circuit. Regarding vessels.

[0002]

2. Description of the Related Art A DC circuit breaker protects a circuit from overcurrent by restoring electrical insulation between main electrodes at a current zero point generated by inserting a current of opposite polarity and interrupting the current. For example, FIG. 11 shows a circuit diagram of a conventional general DC breaker, and FIG. 12 shows its operating principle.

In FIG. 11, reference numeral 1 is a DC breaker, which is a vacuum valve 2, a commutation capacitor 5, a commutation reactor 6, and the like.
It is composed of a trigger gap 8, an electromagnetic repulsion coil 3, a short ring 4, an overcurrent trip device 7, and a zinc oxide nonlinear resistor 9.

A conventional DC circuit breaker 1 constructed in this way
In FIG. 3, the commutation capacitor 5 is charged in advance by a charging device so that the DC power supply 10 side is negative and the load 11 side is positive as shown in the figure. An overcurrent Io flows into the main circuit from the time to, and at the same time when it is detected by the overcurrent trip device 7, the electromagnetic repulsion coil 3 is excited and an electromagnetic repulsion force is generated between the short ring 4 and the vacuum circuit. The movable electrode 2b of the bulb 2 is separated from the fixed electrode 2a, and an arc is generated between the movable electrode 2b and the fixed electrode 2a. At this time, since the axial parallel magnetic flux φo generated by the fixed electrode 2a and the movable electrode 2b itself acts on the arc, the arc is stably maintained between the electrodes.

When the trigger gap 8 is ignited at time t2 after opening the vacuum valve 2, a commutation condenser 5-commutation reactor 6-trigger gap 8-a closed circuit of the vacuum valve 2 is formed and commutation occurs. The capacitor 5 is discharged and the reverse current Ic1 flows in the direction opposite to the main circuit current.

When this current causes the current Io + Ic1 flowing through the vacuum valve 2 to reach the zero point at time t3, the vacuum valve 2 is extinguished, and the main circuit current is transferred to the circuit of the commutation capacitor 5-commutation reactor 6-trigger gap 8. Shed.

The energy stored in the inductance on the load side is converted into the charging energy of the commutation capacitor 5, and when the voltage of the commutation capacitor 5 rises to reach the operating voltage of the zinc oxide nonlinear resistor 9, the zinc oxide is discharged. The non-linear resistor 9 discharges and completes the breaking operation.

[0008]

In the above prior art, as shown in FIG. 9, the damping speed of the axial parallel magnetic flux φo generated between the electrodes by the overcurrent Io flowing in the main circuit is inserted from time t2. Since it is slower than the cycle of the reverse current Ic1 generated, the magnetic flux φr remains as shown by φo ′ even at the zero point of the overcurrent Io + Ic1 of the main circuit generated at the time t3 by the reverse current Ic1. Therefore, at time t3
The diffusion of charged particles between the electrodes at the current zero point of the electrode is hindered in the radial direction, and the insulation recovery speed between the electrodes decreases.As a result, the transient recovery voltage cannot be withstood and re-arcing occurs, and the interrupting performance is suppressed. There was a drawback that

An object of the present invention is to provide a DC circuit breaker having a high breaking performance by improving the insulating speed between electrodes.

[0010]

In order to achieve the above object, the present invention provides a main circuit with a plurality of circuits for inserting a current, and controls each current inserting circuit independently, so that the main electrodes are electrically connected to each other. A current zero is generated at an arbitrary time according to the change in magnetic flux density.

[0011]

[Function] In a parallel magnetic field type electrode which improves the breaking performance by applying a magnetic field in the axial direction to the arc, the eddy current flowing through the electrode or holder causes the magnetic field in the axial direction between the electrodes even at the current zero point. To remain.

At the current zero point, the charged particles diffuse in the radial direction, but the motion has the property of being along the direction of the magnetic force lines. Therefore, if an axial magnetic field remains between the electrodes, the charged particles will be distributed between the electrodes. It is supplemented and prevents rapid diffusion in the radial direction. Therefore, there is a phenomenon that the insulation recovery speed between the electrodes is suppressed and the blocking performance is suppressed. This phenomenon becomes a particular problem when the breaking current is large or when the current change rate at the current zero point is large.

According to the present invention, a plurality of circuits for inserting a current are provided in the main circuit, and each current inserting circuit is independently controlled. First, a current having a polarity opposite to that flowing through the main circuit is inserted into the main circuit current by the first current inserting circuit, and the absolute value of the current flowing through the vacuum valve, which is a part of the main circuit, is narrowed down.
As a result, the axial magnetic field between the main electrodes of the vacuum valve decays with a certain time constant after a change in the current due to the eddy current in accordance with the change in the absolute value of the current flowing through the vacuum valve.

Next, when the axial magnetic field between the main electrodes is attenuated to a sufficiently small level, a current that does not disturb the axial magnetic field between the main electrodes is inserted into the main circuit current by the second current inserting circuit to generate a current. Generate a zero point. At this time, since the axial magnetic field between the main electrodes is attenuated to a sufficiently small value, diffusion of charged particles in the radial direction is not hindered and the insulation recovery speed is not suppressed, so that the blocking performance can be improved. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operating principle of the embodiment of the present invention shown in FIG.

In FIG. 1, reference numeral 1 denotes a DC circuit breaker, which is a vacuum valve 2, an electromagnetic repulsion coil 3, a short ring 4, an overcurrent trip device 7, a zinc oxide nonlinear resistor 9, a commutation capacitor 5a and a resistor 15a. , A first current insertion circuit composed of a trigger gap 8a, and a second current insertion circuit composed of a commutation capacitor 5b, a commutation reactor 6b, and a trigger gap 8b.

In the circuit breaker 1 thus constructed, the commutation capacitors 5a and 5b are charged in advance to the polarity shown in the drawing by a charging device (not shown). Time t
An overcurrent Io flows from o to the main circuit and is detected by the overcurrent trip device 7, and at the same time, the electromagnetic repulsion coil 3 is excited and an electromagnetic repulsion force is generated between the short circuit and the short ring 4. The second movable electrode 2b is separated from the fixed electrode 2a, and an arc is generated between the movable electrode 2b and the fixed electrode 2a. At this time, since the axial parallel magnetic flux φo generated by the fixed electrode 2a and the movable electrode 2b itself acts on the arc, the arc is stably maintained between the electrodes.

When the trigger gap 8a is fired at time t2 after opening the vacuum valve 2, a commutation capacitor 5a-resistor 15a-trigger gap 8a-a closed circuit of the vacuum valve 2 is formed, and the commutation capacitor 5a. Is discharged and the reverse current Ic1 is inserted into the vacuum valve 2 which constitutes a part of the main circuit. The current flowing through the vacuum valve 2 due to the current Ic1 is I
As a result, the axial parallel magnetic flux φo generated by the current flowing through the electrode itself is delayed to the change of the current like φo ′ due to the eddy current flowing in the electrode, the holder, etc. It decays with a constant.

Therefore, the current Io + flowing through the vacuum valve 2 at time t4 when the axial magnetic flux between the main electrodes is attenuated sufficiently small.
Time t3 so that Ic1 + Ic2 can form a current zero point
When the trigger gap 8b is fired at, the commutation capacitor 5
b-Commutation reactor 6b-Trigger gap 8b-The closed circuit of the vacuum valve 2 is formed, the commutation capacitor 5 is discharged, and the reverse current Ic is applied to the vacuum valve 2 forming a part of the main circuit.
2 is inserted.

When the reverse current Ic2 causes the current Io + Ic1 + Ic2 flowing through the vacuum valve 2 to reach the zero point at time t4, the vacuum valve 2 is extinguished. At this time, the parallel magnetic flux in the axial direction between the main electrodes is attenuated sufficiently small as shown by φo ', and the diffusion of the charged particles in the radial direction is not hindered, so that a good insulation recovery characteristic is exhibited.

After the main circuit current is cut off, the main circuit current is commutated capacitor 5a-resistor 15a-trigger gap 8a.
Circuit and commutation capacitor 5b-commutation reactor 6b-
Commutation occurs in the circuit of the trigger gap 8b. The energy stored in the inductance on the load side is converted into the charging energy of the commutation capacitors 5a and 5b, and when the voltage of the commutation capacitors 5a and 5b rises and reaches the operating voltage of the zinc oxide nonlinear resistor 9, The zinc oxide nonlinear resistor 9 discharges and completes the breaking operation.

By thus providing a plurality of current insertion circuits, the axial magnetic flux between the main electrodes is attenuated to a sufficiently small value before the current zero point, thereby improving the insulation recovery characteristic after the current interruption and the DC interruption. It is possible to improve the shutoff performance of the container.

Next, FIG. 3 is a circuit diagram showing a second embodiment of the present invention, and FIG. 4 is an explanatory diagram of the operating principle of the second embodiment of the present invention shown in FIG. In this embodiment, a first current insertion circuit including a commutation capacitor 5a, a resistor 15a, and a trigger gap 8a, a commutation capacitor 5b, and a commutation reactor 6 are provided.
b is the same as the embodiment of the present invention shown in FIG. 1 in that the second current inserting circuit composed of the trigger gap 8b is provided, but the commutation capacitor 5a and the second current inserting circuit of the first current inserting circuit are provided. This is an example in which the charge polarities of the commutation capacitors 5b of the current insertion circuit are opposite to each other. In the present embodiment, as shown in FIG. 4, when the trigger gap 8b is ignited at time to and the current Ic1 is inserted by the first current inserting circuit, the polarities of the current Ico + Ic1 flowing through the vacuum valve are reversed and the absolute values are absolute. The value is narrowed down.

At this time, the axial parallel magnetic flux φ between the electrodes is attenuated with a time constant delayed from the change of the current like φo 'because of the eddy current flowing through the electrodes and the holder. φ ′
At time t4 at which the current decays sufficiently small, the trigger gap 8b is ignited at time t3 so that the current Ico + Ic1 + Ic2 flowing through the vacuum valve 2 can form a current zero point, and the reverse current (polarity positive current) Ic2 is generated. Insert into the vacuum valve 2.

Due to this current Ic2, when the current Io + Ic1 + Ic2 flowing through the vacuum valve 2 reaches the zero point at time t4, the vacuum valve 2 is extinguished. At this time, since φo ′ is attenuated to a sufficiently small level, diffusion of charged particles in the radial direction is not hindered, and good insulation recovery characteristics are exhibited.

Thus, the electric current I to be inserted into the vacuum valve is
Even if the polarities of c1 and Ic2 are opposite to each other, the same effect as that of the embodiment shown in FIG. 1 can be obtained.

Next, FIG. 5 is a circuit diagram showing another embodiment of the present invention. The first current inserting circuit is composed of a capacitor 5a, a resistor 15a and a trigger gap 8a, and a second current inserting circuit is formed. Similarly, it is composed of a capacitor 5b, a resistor 15b, and a trigger gap 8b.

FIG. 6 is a circuit diagram showing a fourth embodiment of the present invention, in which the charging polarities of the capacitors 5a and 5b in the embodiment shown in FIG. 5 are opposite to each other.

Here, the embodiment shown in FIG. 5 is obtained by replacing the second current inserting circuit of the embodiment shown in FIG. 1 with an RC circuit, and its operating principle corresponds to that of FIG. The embodiment shown in FIG. 6 is obtained by replacing the second current inserting circuit of the embodiment shown in FIG. 3 with an RC circuit, and its operation principle corresponds to that of FIG. 4, and the same action and effect can be obtained. it can.

Next, FIGS. 7 to 10 are circuit diagrams showing fifth to eighth embodiments, in which the first current insertion circuit is composed of an LC n-stage π type and a trigger gap. is there. FIG. 7 shows an example in which the second current insertion circuit is composed of the capacitor 5b and the reactor 6b, and FIG. 8 has the same configuration as that of FIG. 7, but the capacitor 5a and the second current insertion circuit of the first current insertion circuit are The charging polarities of the capacitor 5b are opposite to each other. Further, FIG. 9 shows an example in which the second current insertion circuit is composed of the capacitor 5b and the resistor 15b, and FIG.
9 has the same configuration as in FIG. 9, but the charging polarities of the capacitor 5a of the first current inserting circuit and the capacitor 5b of the second current inserting circuit are opposite to each other. 7 and 9 correspond to FIG. 1, and FIG. 8 and FIG. 10 correspond to FIG. 2, and similar operational effects can be obtained. Further, since the LCn stage π-type circuit is used for the first current insertion circuit, the quasi-steady portion of the reverse current Ic1 is different from the embodiment shown in FIGS. 1 to 6 in which the RC circuit is used for the first current insertion circuit. Can be taken longer, and the degree of freedom at time t3 when the current Ic2 is inserted can be increased.

Further, in the present invention, by providing a plurality of current insertion circuits, even if the current interruption fails due to the first and second current insertion, the next interruption operation is promptly performed by the third and fourth current insertion. It is also conceivable that the operation moves to. Further, an operation in which the absolute value of the main current is narrowed down step by step prior to the current zero point is also conceivable.

[0033]

According to the present invention, the absolute value of the current flowing through the main electrode is suppressed to a small value by the current inserted by the first current inserting circuit, and the axial direction between the main electrodes is attenuated after the current change. After the magnetic flux density is sufficiently attenuated, the second
The current inserted by the current insertion circuit causes a zero point in the current flowing through the main electrode. Then, the residual magnetic flux at the current zero point is suppressed, diffusion of charged particles in the radial direction is not hindered, the insulation recovery characteristic after current interruption is improved, and the interruption performance of the DC circuit breaker can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation principle of one embodiment of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of the operation principle of the second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a sixth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a seventh embodiment of the present invention.

FIG. 10 is a circuit diagram showing an eighth embodiment of the present invention.

FIG. 11 is a circuit diagram of a conventional general DC breaker.

FIG. 12 is an explanatory diagram of an operating principle of a conventional general DC breaker.

[Explanation of symbols]

1 ... DC circuit breaker, 2 ... Vacuum valve, 2a ... Fixed electrode, 2
b ... movable electrode, 3 ... electromagnetic repulsion coil, 4 ... short ring, 5a, 5b ... commutation capacitor, 6a, 6b ... commutation reactor, 7 ... overcurrent trip device, 8a, 8b ... trigger gap, 9 ... oxidation Zinc non-linear resistance, 10 ... DC power supply, 11 ... Load.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shunkichi Endo 4026 Kuji Town, Hitachi City, Ibaraki Prefecture 4026, Hitachi Research Institute, Ltd. Hitachi Research Laboratory

Claims (7)

[Claims] 1. A vacuum container, a main electrode provided in the vacuum container, which is provided with at least a pair of means for generating a magnetic flux component in the direction of contact and separation, and a rear surface of the main electrode to the outside of the vacuum container. A DC circuit breaker comprising a rod extending, a vacuum valve composed of an arc shield, and a circuit for inserting a current into a current main circuit including the vacuum valve, and a plurality of circuits for inserting a current into the current main circuit are provided. A DC circuit breaker characterized by that. 2. The DC circuit breaker according to claim 1, wherein the plurality of circuits for inserting current into the current main circuit are a circuit including a capacitor, a resistor and a trigger gap, and a circuit including a capacitor, a reactor and a trigger gap. 3. The DC circuit breaker according to claim 1, wherein the plurality of circuits for inserting current into the current main circuit are circuits including capacitors, resistors, and a trigger gap. 4. The circuit according to claim 1, wherein the plurality of circuits for inserting a current into the current main circuit are π of a capacitor and a reactor.
A DC circuit breaker, which is a circuit consisting of a mold circuit and a trigger gap, and a circuit consisting of a capacitor, a reactor and a trigger gap. 5. The plurality of circuits for inserting a current into the current main circuit according to claim 1, wherein:
A DC circuit breaker, which is a circuit consisting of a mold circuit and a trigger gap, and a circuit consisting of a capacitor, a resistor and a trigger gap. 6. The method according to claim 1, 2, 3, 4 or 5.
A DC circuit breaker, wherein each of the plurality of circuits for inserting a current into the current main circuit is a circuit for inserting a current flowing in the main circuit and having a polarity opposite to that of the current to be blocked. 7. The method according to claim 1, 2, 3, 4, or 5,
The plurality of circuits for inserting a current into the current main circuit is a DC circuit breaker including a circuit for inserting a current having a polarity opposite to that of a current to be interrupted flowing in the main circuit and a circuit for inserting a current of the same polarity.