JPS637650B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit breaking device that can be applied to cutting high voltage, large current circuits.

The case where both the conventional device and the device according to the embodiment of the present invention are applied to a DC circuit to cut off a load current will be explained.

Conventionally, there has been a shredding device of this type as shown in the block diagram in FIG. 1 is a switch that generates an arc with a high voltage rise rate (dV/dt), 2, 3
and 4 are a capacitor, a lightning arrester, and a high-resistance discharge resistor connected in parallel to this switch. The lightning arrester 3 is configured to allow only a minute current to flow at the circuit voltage, and to allow a rated current to flow at the maximum allowable voltage, and is made of, for example, zinc dioxide (Z _o O ₂ ).
The discharge resistor 4 is for discharging the charge of the capacitor 2. 5 is a disconnector connected in series to the parallel circuit of each of the above elements. The circuit disconnection device configured in this manner is connected to a DC power source and a smoothing reactor (not shown).

Next, the operation of the conventional circuit breaker described above will be explained in the second section.
This will be explained using figures. FIG. 2 is a curve diagram showing the current flowing through each component and its terminal voltage during operation of a conventional shearing breaker, where the dash-dotted line represents the current and the solid line represents the voltage. Figure a shows the main circuit current, and b
The figure shows the current and voltage of the first part of the switch, the figure c shows the current and voltage of the second part of the capacitor, and the figure d shows the current and voltage of the third part of the lightning arrester. Now, with DC current I ₀ flowing in the main circuit, b
As shown in the figure, when the switch 1 is opened at time _t1 , the arc voltage _V1 rises rapidly. The current I ₂ flowing into the capacitor 2 connected in parallel to the switch 1 is as follows, assuming that the capacitance of the capacitor is C.
Since CdV ₁ /dt, when dV ₁ /dt exceeds I ₀ /C, all the current flows into capacitor 2 as shown in figure c, and as a result, the current flowing through switch 1 becomes zero at time t ₃ . , the switch 1 interrupts the current. Thereafter, the power supply and the reactor continue to charge the capacitor 2, and the voltage V ₂ across it continues to rise until the voltage V ₃ across the lightning arrester 3, which is connected in parallel and has the same voltage value, reaches the protection voltage V _nax . The current I ₀ in the main circuit decreases due to this back electromotive force, and the voltages V ₂ and V ₃ at both ends drop to the circuit voltage V ₀ , resulting in a minute current. After this, when the disconnector 5 is opened at time _t4 ,
The main circuit is suddenly disconnected. Since the charge stored in the capacitor 2 is gradually discharged through the discharge resistor 4, a short circuit current can be prevented from flowing even if the switch 1 is turned on for re-energization.

In the above-mentioned conventional circuit breaking device, the maximum value of the current that can be broken is limited by the arc voltage rise rate of the switch 1, and it is difficult to cut or cut an excessively large current. I couldn't do it.

This invention connects in series a switch that has excellent shearing ability for a circuit with a high current ramp rate and a current limiting element that generates a reverse voltage with a high rate of rise when operated, and connects a capacitor to this series circuit. , a lightning arrester and a discharge resistor are connected in parallel, and after the switch is opened, the load of the main circuit is temporarily short-circuited in whole or in part by a short-circuit means, and the current-limiting element is operated by a temporary large current. By commutating the main circuit current to the capacitor, it is possible to cut off a larger current than before, and the recovery voltage after current limiting and breakage is taken over by a switch with a fast insulation recovery speed. The purpose of the present invention is to provide a large-capacity, high-voltage circuit disconnection device that can be applied to higher voltage circuits.

FIG. 3 is a block diagram of a circuit breaker device according to an embodiment of the present invention. Reference numeral 6 denotes a switch having excellent insulation breaking ability for a circuit with a high current gradient rate, such as a vacuum insulation breaker, a gas insulation breaker, etc.
7 is a current limiting element connected in series to this switch 6;
Consists of a self-restoring current limiting element (permanent fuse) using an alkali metal. 8 is a load inserted into the main circuit, 9 is a thyristor connected in parallel to this load, and is energized by an ignition circuit (not shown) that receives an external command to temporarily short-circuit the load 9. The series circuit of the switch 6 and the current limiting element 7 includes a capacitor 2,
Lightning arrester (for example made of zinc dioxide) 3 and discharge resistor 4
are connected in parallel, and a disconnector 5 is connected in series to these parallel circuits.

When energized, the switch 6 and the disconnector 5 are closed, and the thyristor 9 is in a non-energized state. During the disconnection operation, the switch 6 is first opened, then the thyristor 9 is fired to temporarily short-circuit the load 8, and finally the disconnector 5 is opened.

The operation of the shredder according to the above embodiment will be explained next. In a state where the main circuit current is flowing through the load 8, the current limiting element 7, the switch 6, and the disconnector 5, when the switch 6 is opened due to a breakage, an arc is generated and the current continues to flow. Next, when the thyristor 9 is temporarily ignited, the load 9 is short-circuited and a large current temporarily flows in the main circuit, and the alkali metal in the current-limiting element 7 is vaporized, generating a reverse voltage with a high rate of increase. do. The voltage across the capacitor 2 connected in parallel to the current limiting element 7 also rises rapidly, and the charging current of the capacitor 2, which is proportional to the voltage increase rate (dV/dt), reaches the main circuit current value. As a result, the switch 6 reaches a current zero point, and the series circuit is finally cut off. The main circuit current continues to charge the capacitor 2, and when the voltage across the capacitor 2 eventually exceeds the circuit voltage, a back electromotive force is generated and the main circuit current begins to decrease. In the end, the voltage across the lightning arrester 3 and the discharge resistor 4 decreases to the circuit voltage, resulting in a minute current. At this point, the disconnector 5 is opened to complete cutting off the minute current.

The self-recovery type current limiting element 7 returns to a low resistance state after operation, and the charge in the capacitor 2 is discharged by the discharge resistor 4.
After that, by closing the disconnector 5 and the switch 6, the power can be re-energized.

When a short-circuit accident occurs in the load 8 and a large current flows in the main circuit, the current limiting element 7 immediately operates to perform a current limiting action and the switch 6 is opened. The subsequent operations of the capacitor 2, lightning arrester 3, discharge resistor 4, and disconnector 5 are the same as when the thyristor 9 is operated.

FIG. 4 is a block diagram of a circuit breaker according to another embodiment of the present invention. Capacitor 2, lightning arrester 3
A disconnector 5 is connected in series to the parallel circuit of the discharge resistor 4 and the discharge resistor 4, and these connection circuits are connected in parallel to the series circuit of the current limiting element 7 and the switch 6.

In addition, in the description of the above embodiment, the capacitor 2
Although it was assumed that the commutation would occur instantaneously, in actual circuits there is inductance in the line, so it takes time for the commutation to occur. This inductance plays the role of lowering the current slope (dI/dt) of the switch 6, so if it is particularly necessary for the performance of the switch 6, a reactor with a large inductance is used, as shown in the configuration diagram in Figure 5. 10 may be inserted in series with capacitor 2.

Further, in the above embodiment, all the loads 8 of the main circuit are temporarily short-circuited, but depending on the case, some of them may be temporarily short-circuited. Further, although the thyristor 9 is used as the temporary short-circuiting means in the above embodiment, a switching mechanism such as a switch may be provided in the shunt of the load 8.

Furthermore, in the above embodiment, a self-restoring current limiting element (permanent fuse) was used as the current limiting element.
In addition to this, a large number of spare parts are provided for current-limiting type fuses in addition to those installed in the circuit, and after the parts installed in the circuit are activated, a means is provided to automatically replace them with spare parts using a replacement mechanism such as an electric operation. It can also be in a different shape.

Furthermore, although the above embodiments have been described with reference to the case where the present invention is applied to a DC circuit, it is also possible to apply the present invention to an AC circuit.

As described above, according to the present invention, a switch having an excellent shear breaking ability for a circuit with a high current ramp rate and a current limiting element that generates a reverse voltage with a high rate of increase upon operation are connected in series. A capacitor, a lightning arrester, and a discharge resistor are connected in parallel to this series circuit, and short-circuit means is provided to temporarily short-circuit all or part of the load of the main circuit after the switch is opened.
By operating the current limiting element with a large current caused by this temporary short circuit, the main circuit current is commutated to the capacitor, so it is possible to cut off a larger current more easily than before, and further, Since the recovery voltage after current limiting or disconnection is taken care of by a switch with a fast insulation recovery speed, it can be applied to higher voltage circuits, and a larger capacity, higher voltage circuit disconnection device can be obtained.

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional circuit shearing device, Figure 2
The figure is a voltage/current curve diagram of each component part during operation of the circuit disconnection device shown in FIG. 1, FIG. 3 is a block diagram of a circuit disconnection device according to an embodiment of the present invention, and FIG. 5 is a block diagram of a circuit disconnection device according to other different embodiments of the present invention. 2... Capacitor, 3... Lightning arrester, 4... Discharge resistor,
5... Disconnector, 6... Switch, 7... Current limiting element, 8... Load of main circuit, 9... Thyristor. In addition, the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A switch having excellent shearing performance for a circuit with a high current ramp rate, which is connected in series with the switch and generates a reverse voltage with a high rate of rise through current limiting operation. A current-limiting element, a short-circuit means for temporarily short-circuiting all or part of the load of the main circuit after opening of the switch and operating the current-limiting element with a temporary large current; A capacitor is connected in parallel to the series circuit of the current limiting element, and the main circuit current is commutated by the operation of the current limiting element. A lightning arrester through which a current is commutated, a discharge resistor connected in parallel to the capacitor and discharging the charge of the capacitor, and a circuit line from the parallel circuit of the capacitor, surge arrester and discharge resistor, so that the capacitor and surge arrester operate. A circuit disconnection device equipped with a disconnector that disconnects the main circuit current that has become a minute current. 2. The circuit breaking device according to claim 1, wherein the current limiting element is a self-restoring current limiting element. 3 A patent characterized in that the current-limiting element is equipped with a number of current-limiting type fuses as spare parts in addition to the ones installed in the circuit, and after the installed parts are operated, they are automatically replaced with spare parts by a replacement mechanism. A circuit breaking device according to claim 1.