JP5632304B2 - Circuit breaker for wiring and DC power system - Google Patents

Description

  The present invention relates to a circuit breaker for a DC circuit and a DC power system such as a solar power generation system to which the circuit breaker is applied.

First, FIG. 2 shows a system diagram of a DC power system constructed by linking a plurality of solar battery panels, taking a solar power generation system as an example.
In FIG. 2, 1 is a solar cell panel composed of an assembly of solar cell modules, 2 is a connection box divided into groups and connected to the solar cell panel 1, 3 is a current collection box, 4 is a connection box 2, and a current collection box 3. 5 is a power conditioner linked to a commercial power supply system (not shown), 6 is a wiring cable, and in the illustrated example, eight solar modules are installed. The battery panel 1 is divided into two groups of four, and the circuit breaker 4 is connected hierarchically to the power conditioner 5 via the connection box 2 and the current collection box 3. Are connected by a cable 6.

  The photovoltaic power generation system in FIG. 2 is a grid-connected type that is linked to a commercial power supply system via a power conditioner 5, but the DC output is directly fed to a DC load (DC equipment). In the independent photovoltaic power generation system, a DC / DC converter is used instead of the power conditioner 5 to link to the DC distribution path. Moreover, the said circuit breaker 4 for wiring has used the duty and function required as a circuit breaker for DC circuits.

  By the way, in the DC power system of FIG. 2, the middle point of the cable 6 that hierarchically connects the circuit breakers 4 between the solar panel 1 and the power conditioner 5 is disconnected during energization. Or when the circuit is opened because the cable 6 is disconnected from the terminal of the device, unlike the alternating current (passing through the current zero point for each cycle), the arc ignited at the open location continues and secondary such as a fire There is a danger of causing a disaster.

  Therefore, as a measure for preventing the occurrence of an arc due to the unexpected disconnection accident of the cable 6 described above, a capacitor element is connected between the positive electrode and the negative electrode of the circuit in the middle of the DC wiring path. The capacitor element is charged to approximately the same potential as the potential of the wiring path, and when a wiring cable disconnection accident occurs upstream from the connection point of this capacitor element, the potential difference between both ends of the disconnection point is kept small. A current interruption support circuit that prevents the occurrence of arcs is known (for example, see Patent Document 1).

JP2009-181864A (FIG. 3)

  If the current interruption support circuit of Patent Document 1 is applied to a DC power system such as the photovoltaic power generation system shown in FIG. 2, it occurs at the disconnection point due to a cable disconnection accident or the like occurring in the wiring path in the system. Although it can be expected to suppress arcing, if the distance between the capacitor connection point of the current interruption support circuit and the disconnection point of the wiring path is long, the potential difference at the disconnection point is expanded due to the influence of the line impedance. Therefore, the effect of the arc suppression function cannot be exhibited.

  On the other hand, in a large-scale solar power generation system constructed by dispersing and arranging a large number of solar cell panels, the length of cables wired between each solar cell panel, junction box, and current collection box is several hundred. Since it reaches even a meter, the influence of the line impedance cannot be ignored. Therefore, in order to effectively demonstrate the arc suppression function of the current interruption support circuit in such a large-scale system, it is necessary to arrange a large number of current interruption assistance circuits for each short distance in the wiring path in the system, The wiring work and cost required for the construction will also increase.

  The present invention has been made in view of the above points. In constructing a DC power system such as the above-described photovoltaic power generation system, the present invention is intended for wiring of connection boxes and current collection boxes arranged at important points in the system. It is an object of the present invention to provide a circuit breaker for wiring and a DC power system that can suppress the occurrence of arcs due to cable disconnection of the system wiring path, disconnection from the terminal, etc. by utilizing the circuit breaker.

In order to achieve the above object, according to the present invention, a multi-pole contact mechanism, a contact switching mechanism, an overcurrent trip device, a power supply side terminal, and a load side terminal are mounted on the outer case. In the circuit breaker for
A capacitor element is connected between the positive electrode terminal and the negative electrode terminal of the load side terminal, and is built in the outer case of the circuit breaker for wiring. Further, the capacitor element, and the rectifying device and the + terminal of said load terminal via a parallel circuit of a resistor element - connected in series between the terminal (claim 2).

  In a DC power system in which a plurality of distributed DC power supplies are linked and constructed, and the circuit breakers for wiring are hierarchically connected in the system in association with the DC power supplies, the capacitor elements described above are used for the circuit breakers for wiring. A built-in wiring circuit breaker is applied (claim 3).

  As described above, as a countermeasure to suppress the occurrence of arcs due to cable disconnection and terminal disconnection of the DC wiring path, the load circuit breaker used for the wiring breaker connected to the wiring path has a positive terminal and a negative terminal. By connecting a capacitor element between them, even if an unexpected cable disconnection accident occurs in the wiring path upstream of the DC power system to which this circuit breaker is applied, an arc is generated at the disconnection point. Can be prevented. Further, by connecting this capacitor element to the load side terminal of the circuit breaker for wiring, the original circuit breaker performance of the circuit breaker for wiring is not impaired.

  Then, by connecting the circuit breaker with a built-in capacitor element according to the present invention to the DC power system such as a photovoltaic power generation system (see FIG. 2) in a hierarchy in the system, Even if an unexpected cable disconnection accident occurs, the capacitor element of the circuit breaker connected to the downstream side near the disconnection point functions on the same principle as the current interrupting support circuit of Patent Document 1 and functions as a disconnection point. It is possible to prevent the occurrence of an arc, thereby improving the safety and reliability of the DC power system. Moreover, when a DC power system is constructed by applying a wiring breaker with a built-in capacitor element, the current interruption support circuit of Patent Document 1 is dispersed in the system and separated from the circuit breaker. Construction work can be reduced without the need for work such as connection.

It is a figure showing the circuit breaker for wiring by the Example of this invention, (a) is an equivalent circuit schematic, (b) is a disassembled perspective view showing an assembly structure. 1 is a system configuration diagram of a photovoltaic power generation system that is an example of a DC power system. FIG.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples shown in FIGS. First, in the circuit breaker 4 shown in FIGS. 1 (a) and 1 (b), reference numeral 7 denotes an outer case having a divided structure composed of a frame 7a and a cover 7b. The outer case 7 includes a power supply side terminal 8 and a load side. In addition to the terminal 9, the main circuit contact mechanism 10, the switching mechanism 11, the arc extinguishing device 12, the overcurrent tripping device 13, the switching operation handle 14, etc., an arc suppression circuit 15 is incorporated in the vicinity of the load side terminal 9. The arc suppression circuit 15 is connected between the terminal conductors of the positive electrode terminal 9a and the negative electrode terminal 9b of the load side terminal.

  The arc suppression circuit 15 has a configuration in which a capacitor element 16, a resistance element (charging resistor) 17, and a diode 18 as a rectifying element are connected in series and parallel as shown in FIG. 18 is connected with a reverse polarity with respect to the positive electrode terminal 9a. In the circuit of the illustrated example, the resistor element 17 is connected in series with the capacitor element 16 so as to suppress the rush current at the initial stage of charging. However, when a load with low impedance is connected as in a solar power generation system or the like. However, in a system in which a large current does not flow because of the voltage / current characteristics of the solar cell, the resistor element 17 may be omitted and the capacitor element 16 may be directly connected between the terminals.

  Then, with respect to the photovoltaic power generation system shown in FIG. 2, the connection box 2 and the current collection box 3 arranged hierarchically in the system are provided with the above-described built-in capacitor type circuit breaker 4. The base solar cell panel 1 is connected in a linked manner.

  In the DC power system described above, when the circuit breaker 4 connected to the distribution line at each level is energized, the capacitor element 16 is charged to substantially the same potential as the line voltage of the distribution line. Therefore, even when the cable 6 of the distribution path is unexpectedly disconnected or disconnected from the connection terminal in this state, a potential difference does not occur between the upper part and the lower part of the open part. Therefore, it is possible to prevent the occurrence of an arc at the disconnection point. In addition, as shown in the system diagram of FIG. 2, the circuit breakers 4 are distributed at important points in the system and installed in the junction box 2 and the current collector box 3. However, the occurrence of an arc can be effectively prevented by the wiring breaker with a built-in capacitor element located near the disconnection point without being greatly affected by the line impedance.

  1 is not limited to the photovoltaic power generation system shown in FIG. 2, but various combinations of solar cell panels and fuel cells are possible. Of course, the present invention can be similarly applied to such a distributed DC power supply system.

DESCRIPTION OF SYMBOLS 1 Solar cell panel 2 Connection box 3 Current collection box 4 Circuit breaker 6 Cable 7 Outer case of circuit breaker 9 Load side terminal 9a + Pole terminal 9b-Pole terminal 10 Contact mechanism 11 Switching mechanism 13 Overcurrent trip device 15 Arc Suppression Circuit 16 Capacitor Element 17 Resistance Element 18 Diode

Claims (3)

In circuit breakers for DC circuits with multi-pole contact mechanisms, contact switching mechanisms, overcurrent trip devices, and power supply side terminals and load side terminals in the outer case.
A + terminal of the load terminal - circuit breaker, characterized in that the interior to the outer casing by connecting a capacitor element between the electrode terminal. In MCCB according to claim 1, wherein the capacitor element is, the rectifying element and the + terminal of said load terminal via a parallel circuit of a resistor element - that are serially connected between the terminal The circuit breaker for wiring.   In a DC power system constructed by linking a plurality of distributed DC power supplies, wherein the circuit breakers for wiring are hierarchically connected in association with the DC power supply, the circuit breaker for wiring is claimed in claim 1. A DC power system characterized by applying the built-in capacitor circuit breaker described in 1.