JP2012195121A - Circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized circuit breaker having a high breaking performance by increasing a capacity of a capacitor part configuring a resonance circuit part and by miniaturizing the capacitor part.SOLUTION: A circuit breaker has: a main contact 11 inserted in a DC circuit 1 provided between a DC power supply 20 and a load 30; and a resonance circuit part connected in parallel to the main contact 11, the resonance circuit part in which a coil 13 and a capacitor part 14 are connected in series. An oscillating current generated at an arc A of the main contact 11 and the resonance circuit part at the time of current breaking is superimposed on a DC current to generate current zero to a current flowing in the main contact 11 and perform the current breaking. The capacitor part 14 has two sets of circuits in each set of which an aluminum electrolytic capacitor 15 and a diode 16 are connected in parallel so that a positive electrode of the aluminum electrolytic capacitor 15 and a cathode of the diode 16 are connected with each other. The two sets of circuits are connected in series so that the same poles of the aluminum electrolytic capacitors 15 are connected with each other.

Description

  The present invention relates to a circuit breaker, and more particularly to a circuit breaker in which the breaking performance is improved by a resonance circuit in which a coil and a capacitor are connected in parallel with a main contact for switching current.

  FIG. 4 is a circuit diagram showing a configuration of a conventional circuit breaker. As shown in FIG. 4, the circuit breaker 100 has a contact portion 101 and is inserted into a DC circuit composed of a DC power source 120 and a load 130. In the circuit breaker having such a configuration, by raising the voltage of the circuit breaker to the power supply voltage or more, the current flowing through the entire circuit is reduced to the zero point and the direct current is interrupted.

FIG. 5 is an example of current / voltage waveforms during the breaking operation of the circuit breaker 100 shown in FIG. Here, the solid line indicates the current of the entire circuit, and the broken line indicates the waveform of the arc A voltage (arc voltage) generated at the contact portion 101. As shown in FIG. 5, in the configuration shown in FIG. 4, even when the contact portion 101 is opened at time t <b> 11 and the breaking operation is started, the circuit breaker voltage does not rise sufficiently and the current ( It is difficult to reduce the current flowing through the contact portion 101 to the zero point. As described above, in the configuration shown in FIG. 4, the blocking performance is poor or cannot be blocked.
Therefore, a resonance circuit in which a coil and a capacitor are connected in parallel with the contact part of the circuit breaker generates an oscillating current at the time of breaking operation, and superimposes this on a direct current to create a zero point in the current flowing through the contact part and shut off Has been proposed (see, for example, Patent Documents 1 to 3).

  FIG. 6 is a diagram illustrating a general configuration of a circuit breaker provided with a resonance circuit unit. As shown in FIG. 6, the circuit breaker 100 has a contact part 101, an auxiliary contact 102 connected in series to the contact part 101, a coil 103 connected in parallel to the contact part 101, and a capacitor 104 connected in series. And a resonance circuit unit. In the circuit breaker 100 having such a configuration, an arc A is generated in the contact portion 101 when the contact is opened, and an oscillating current is generated in a closed loop circuit including the contact portion 101, the coil 103, and the capacitor 104 along with the generation of the arc voltage. . Then, this oscillating current is superimposed on the direct current flowing through the contact portion 101, so that the current flowing through the contact portion 101 reaches the zero point, the arc voltage rises, and the current that is energized through the arc A is interrupted. Is done. After reaching the current zero point at the main contact 101, the voltage of the DC power supply 120 is applied to the circuit on the coil 103 and capacitor 104 side, and the capacitor 104 is charged to the same level as the power supply voltage. Thereafter, the auxiliary contact 102 operates, and the load 130 is completely disconnected from the DC power source 120.

JP 2004-39411 A JP-A-3-67429 JP 54-132776 A

By the way, the oscillating current generated during the breaking operation increases as the capacitance of the capacitor constituting the resonance circuit portion of the breaker increases, so that it can be said that the breaking performance increases as the capacitance of the capacitor increases.
For example, in the circuit breaker 100 shown in FIG. 6, when the inductance of the coil 103 of the resonance circuit unit is 10 μH and the capacitance of the capacitor 104 is 5.6 μF, the power supply voltage of several hundred volts is several tens of A (for example, 50 A). FIG. 7 shows current / voltage waveforms when the direct current is cut off. Here, the solid line in FIG. 7 (a) is the current of the entire circuit, the broken line in (a) is the arc voltage, (b) is the current flowing through the contact part 101, and (c) is the current flowing through the resonant circuit part. As shown in FIG. 7, even when the contact portion 101 is opened at time t21 and the breaking operation is started, the oscillating current generated in the resonance circuit portion is small, and the current flowing through the contact portion 101 reaches the zero point quite easily. I can't. Therefore, the current interruption cannot be completed with certainty at the time when the predetermined period of the desired interruption performance has elapsed since the start of the interruption operation (arrow α).

In this way, in order to cut off several tens of amperes of direct current with a power supply voltage of several hundred volts, if the capacity of the capacitor 104 is several μF, the capacity is too small, and the shut-off performance is poor. Capacitance of several tens of μF to several hundreds of μF is required to cut off several tens of A direct current with a power supply voltage of several hundred volts.
Since the current flowing through the resonance circuit unit is an oscillating current having positive and negative directions, a nonpolar capacitor is generally used as a capacitor constituting the resonance circuit unit. However, even a non-polar capacitor having a relatively large capacity has a capacity of only a few μF at most. Therefore, as described above, in order to realize a capacitor capacity of several tens of μF or more, a plurality of the nonpolar capacitors must be connected in parallel, the resonance circuit section becomes larger, and accordingly, the entire circuit breaker is It will increase in size. For this reason, for example, it has been difficult to apply to a use in which a plurality of circuit breakers are installed on a switchboard or the like.
Therefore, an object of the present invention is to provide a small circuit breaker having a high breaking performance by increasing the capacity and downsizing of the capacitor part constituting the resonance circuit part.

  In order to solve the above problems, a circuit breaker according to the present invention includes a main contact inserted in a DC circuit between a DC power supply and a load, a coil and a capacitor unit connected in series, and in parallel with the main contact. A resonance circuit unit connected to, and at the time of opening the main contact, oscillating current generated in the resonance circuit unit due to arc voltage characteristics of the main contact is superimposed on a direct current flowing through the main contact, A circuit breaker that cuts off current by generating a zero point in the current flowing through the main contact, wherein the capacitor unit connects a polar capacitor and a diode, and a positive electrode of the polar capacitor and a cathode of the diode Thus, there are two sets of circuits connected in parallel, and the two sets of circuits are connected in series so that the same poles of the polar capacitors are connected to each other.

  In this way, since the polar capacitor having a larger capacity than the nonpolar capacitor is used for the capacitor portion, a necessary capacitor capacity can be ensured without connecting many capacitors in parallel. Therefore, it is possible to increase the capacity of the capacitor portion and to reduce the size associated therewith.

Furthermore, since the capacitor portion is composed of two sets of circuits connected in parallel so that the positive electrode of the polar capacitor and the cathode of the diode are connected, the reverse function of the diode causes a reverse current to flow in the polar capacitor. It can be prevented from flowing. That is, it is possible to protect the polar capacitor from the reverse voltage. In addition, since the capacitor portion is configured such that the same poles of two polar capacitors are connected in series, current in either the positive or negative direction can flow in the entire resonance circuit portion. That is, it is possible to deal with an oscillating current having both positive and negative energization directions.
In the above, the polar capacitor is an aluminum electrolytic capacitor.
Thus, since a relatively inexpensive aluminum electrolytic capacitor is applied as the polar capacitor, a circuit breaker can be provided at a low cost.

According to the present invention, a circuit breaker with improved breaking performance can be obtained by a resonance circuit in which a coil and a capacitor portion are connected in parallel with the main contact. In addition, since a polar capacitor having a larger capacity than that of a generally used nonpolar capacitor is used for the capacitor unit, it is possible to realize an increase in the capacity of the capacitor unit and a reduction in size associated therewith.
Therefore, the circuit breaker as a whole can be reduced in size, and can be applied to, for example, a case where a plurality of circuit breakers are installed on a switchboard or the like.

It is a figure which shows the structure of the DC circuit to which the circuit breaker concerning this invention is applied. It is an example of the electric current and voltage waveform at the time of interruption | blocking operation | movement. It is a figure which shows another example of the circuit breaker which concerns on this invention. It is a figure which shows the structure of the conventional circuit breaker (no resonance circuit part). It is an example of the electric current and voltage waveform at the time of interruption | blocking operation | movement of the conventional circuit breaker. It is a figure which shows the structure of the conventional circuit breaker (with a resonance circuit part). It is an example of the electric current and voltage waveform at the time of interruption | blocking operation | movement of the conventional circuit breaker.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Constitution)
FIG. 1 is a diagram showing a configuration of a DC circuit to which a circuit breaker according to the present invention is applied.
In the figure, reference numeral 1 denotes a DC circuit, and a circuit breaker (hereinafter simply referred to as a circuit breaker) 10 is inserted in the DC circuit 1 connecting the DC power supply 20 and the load 30.
The circuit breaker 10 includes a main contact 11 that cuts off / energizes the current by opening and closing the contact. An auxiliary contact 12 for disconnecting the circuit is connected in series to the main contact 11, and the main contact 11 and the auxiliary contact 12 are controlled to be opened and closed by an opening / closing mechanism unit (not shown).

  The main contact 11 is connected in parallel with a resonance circuit unit in which a coil 13 and a capacitor unit 14 are connected in series. Here, the capacitor unit 14 includes two polar capacitors 15a and 15b and two diodes 16a and 16b. Aluminum electrolytic capacitors are used as the polar capacitors 15a and 15b. In the following description, when the aluminum electrolytic capacitors 15a and 15b are collectively described, they are simply abbreviated as the aluminum electrolytic capacitor 15. Similarly, when the diodes 16a and 16b are collectively described, they are abbreviated as a diode 16.

This capacitor unit 14 has a configuration including two sets of circuits in which an aluminum electrolytic capacitor 15 and a diode 16 are connected in parallel so that the positive electrode of the aluminum electrolytic capacitor 15 and the cathode of the diode 16 are connected. The circuits in the set are connected in series so that the negative electrodes of the aluminum electrolytic capacitors 15 are connected to each other.
Since the aluminum electrolytic capacitor 15 is a polar capacitor, it can be energized only in one direction. Therefore, in the present embodiment, the resonance circuit unit is configured to allow both positive and negative currents to flow by connecting the negative electrodes of the aluminum electrolytic capacitors 15a and 15b. In FIG. 1, the direction of flow from the side connected to the high potential of the DC power source 20 (coil 13 side) to the side connected to the low potential (load 30 side) is positive.

  In this embodiment, each aluminum electrolytic capacitor 15 is connected in parallel with a diode 16 capable of conducting a current in a direction in which the aluminum electrolytic capacitor 15 cannot be energized. That is, the cathode of the diode 16 is connected to the positive electrode of the aluminum electrolytic capacitor 15. As a result, the bypass function of the diode 16 enables protection from the reverse voltage of the aluminum electrolytic capacitor 15.

  With the above configuration, the circuit breaker 10 closes the main contact 11 in a steady state, thereby energizing the main contact 11 with a load current. On the other hand, the main contact 11 is opened when an accident current or a load current is interrupted. At this time, an arc A is generated at the main contact 11 and an arc voltage is generated. Here, the voltage characteristic of the arc A is a negative characteristic in which the arc voltage decreases as the current increases. The oscillating current generated in the closed loop circuit composed of the arc A and the resonance circuit unit (the coil 13 and the capacitor unit 14) is superimposed on the direct current flowing through the main contact 11, thereby setting the zero point to the current flowing through the main contact 11. Can be produced and blocked.

The oscillating current is a current having both positive and negative energization directions. When the current flows in the positive direction through the resonance circuit unit, the current flows through the path of the coil 13 → the aluminum electrolytic capacitor 15a → the diode 16b as indicated by the solid line arrow Ia. On the other hand, when the current flows in the negative direction through the resonance circuit section, the current flows through the path of the aluminum electrolytic capacitor 15b → the diode 16a → the coil 13 as indicated by the broken line arrow Ib.
In this way, by bypassing the diode 16a or 16b depending on the direction of current flow through the resonance circuit section, current in the reverse direction is prevented from flowing through the aluminum electrolytic capacitor 15, and both positive and negative current flows in the entire resonance circuit section. To be able to.

(Operation)
Next, the operation of this embodiment will be described.
In the steady state, the main contact 11 and the auxiliary contact 12 are closed, and a DC current determined by the DC power supply 20 and the load 30 flows through the DC circuit 1. In this steady state, when a short circuit accident occurs in the load 30 for some reason, a very short circuit current flows in the DC circuit 1 compared to the current flowing in the steady state. Then, a current detection unit (not shown) detects an overcurrent and starts an operation for driving a switching mechanism unit (not shown) to cut off the short-circuit current. Hereinafter, the procedure of the current interruption operation will be described with reference to FIG.

Here, FIG. 2 shows that in the circuit breaker 10 shown in FIG. 1, the inductance of the coil 13 of the resonance circuit portion is 10 μH, the capacitance of the capacitor portion 14 is 33.6 μF (the capacitances of the aluminum electrolytic capacitors 15a and 15b are 33.6 μF, respectively). ) Is a current / voltage waveform during the shut-off operation. The solid line in FIG. 2A indicates the current of the entire circuit, the broken line in FIG. 2A indicates the arc voltage, (b) indicates the current flowing through the contact portion 11, and (c) indicates the current flowing through the resonant circuit portion. I ₀ is a cut-off current, and V ₀ is a power supply voltage.

  When interrupting the short-circuit current, first, the main contact 11 is opened by the switching mechanism at time t1 in FIG. When the contact is opened, an arc A is generated at the main contact 11, and an arc voltage is generated accordingly, as shown by the broken line in FIG. Then, an oscillating current having a frequency determined by the coil 13 and the capacitor unit 14 is generated in the closed loop circuit including the main contact 11, the coil 13, and the capacitor unit 14 (FIG. 2C). It is superimposed on the flowing direct current (FIG. 2 (b)).

The arc voltage gradually rises with time, and the oscillating current also increases as the arc voltage increases. Then, at time t2, the current flowing through the main contact 11 reaches the zero point, whereby the arc voltage rises, and the current energized via the arc A at time t3 is interrupted, thereby completing the current interruption.
After reaching the current zero point at the main contact 11, the voltage of the DC power supply 20 is applied to the coil 13 and the capacitor 14, so that the aluminum electrolytic capacitor 15 is charged to the same level as the power supply voltage. Thereafter, the auxiliary contact 12 is opened by the opening / closing mechanism so that the load 30 is completely disconnected from the DC power supply 20.

  In this way, an oscillating current is generated by the resonance circuit unit composed of the coil 13 and the capacitor unit 14, and the oscillating current is superimposed on the DC current to create a zero point in the current flowing through the main contact 11 to cut off the current. . At this time, the capacitor is generated so that an oscillation current of a magnitude that can cause the current flowing through the main contact 11 to reach the zero point within a period in which a desired cutoff performance can be realized from the start of the cutoff operation is generated in the resonance circuit unit. The capacity of the unit 14 is set.

  In the above example, the capacitor capacity is set to 33.6 μF in order to efficiently cut off a current of, for example, 50 A with a power supply voltage of several hundred volts. In the present embodiment, an aluminum electrolytic capacitor 15 is used as a capacitor constituting the capacitor unit 14. Such a polar capacitor has a large electrostatic capacity, and a single capacitor having a capacitance of about several tens of μF can be realized. In the present embodiment, since it is necessary to provide two sets of aluminum electrolytic capacitors 15 in order to cope with an oscillating current having both positive and negative energization directions, in order to realize a capacitor capacity of 33.6 μF, the breaker 10 is provided with aluminum. It is only necessary to provide two electrolytic capacitors 15.

  By the way, since an oscillating current having both positive and negative energization directions flows through the resonance circuit unit constituted by the coil 13 and the capacitor unit 14 as described above, conventionally, a nonpolar capacitor has been used as the capacitor constituting the resonance circuit unit. I was using it. However, even a non-polar capacitor having a relatively large capacitance has a capacitance of about several μF. In the circuit breaker 100 having the configuration shown in FIG. 6, when a nonpolar capacitor is used as the capacitor 104 constituting the resonance circuit unit and the capacitance of the capacitor 104 is set to 5.6 μF, the current / voltage waveform during the breaking operation is As shown in FIG.

  As shown in FIG. 7, even when the contact portion 101 is opened at time t21 and the breaking operation is started, the oscillating current generated in the resonance circuit portion is small, and from the time when the breaking operation starts (time t1) in FIG. At the time of the arrow α when a period equivalent to the period until completion of current interruption (time t3) has elapsed, the current flowing through the contact portion 101 cannot reach the zero point. Thus, when the capacitance of the capacitor constituting the resonance circuit unit is small, the cutoff performance is poor.

In order to make the current flowing through the contact part 101 reach the zero point effectively, for example, in order to increase the capacitance of the capacitor part to 33 μF or more using a film capacitor of 5.6 μF, it is necessary to connect six capacitors in parallel. There is. In this case, the capacitor portion is enlarged, and as a result, the entire circuit breaker is enlarged.
On the other hand, in the present embodiment, a polar capacitor having a larger capacitance than that of a nonpolar capacitor is used for the capacitor unit constituting the resonance circuit unit. As a result, a capacity (several tens of μF to several hundreds of μF) necessary for causing the current flowing through the main contact 11 to reach the zero point can be realized with a small number of capacitors. That is, by using a polar capacitor, it is not necessary to connect a large number of capacitors in parallel in order to secure the capacity, and the entire circuit breaker can be reduced in size.

(effect)
As described above, in the present embodiment, the capacitor portion constituting the resonance circuit portion connected in parallel with the main contact is constituted by a polarized capacitor having a higher capacitance than other types of capacitors, so that the capacitor portion is large. Capacitance and size reduction can be achieved. Further, since a relatively inexpensive aluminum electrolytic capacitor is used as the polar capacitor, a circuit breaker can be provided at a low cost.
Furthermore, the capacitor part composed of a polar capacitor is composed of two aluminum electrolytic capacitors and two diodes. Then, two sets of circuits connected in parallel so that the positive electrode of the aluminum electrolytic capacitor and the cathode of the diode are connected are made, and the two sets of circuits are connected in series so that the negative electrodes of the aluminum electrolytic capacitor are connected.

As a result, by bypassing the diode depending on the direction of current flow through the resonance circuit unit, one of the positive and negative currents can flow through the entire resonance circuit unit while protecting one aluminum electrolytic capacitor from a reverse voltage. . Therefore, during the current interruption operation, an oscillating current that can effectively reach the zero point of the current flowing through the main contact of the circuit breaker can be appropriately generated, and a circuit breaker with high interruption performance can be obtained.
As described above, it is possible to provide a circuit breaker that is small and has high breaking performance. As a result, for example, the present invention can be applied to an application in which a plurality of circuit breakers are installed on a switchboard or the like.

(Modification)
In the above embodiment, the case where the negative electrodes of the aluminum electrolytic capacitors 15 are connected in series has been described. However, as shown in FIG. 3, the positive electrodes of the aluminum electrolytic capacitors 15 can also be connected in series.
In this case, when the current flows in the positive direction through the resonance circuit unit, the current flows through the path of the coil 13 → the diode 16b → the aluminum electrolytic capacitor 15a as indicated by the solid line arrow Ia. On the other hand, when the current flows in the negative direction through the resonance circuit section, the current flows through the path of the diode 16a → the aluminum electrolytic capacitor 15b → the coil 13 as indicated by the broken line arrow Ib. Therefore, even with the circuit configuration shown in FIG. 3, the same operation as in the circuit configuration shown in FIG. 1 can be realized.
(Application examples)
In the above embodiment, the case where an aluminum electrolytic capacitor is used as the polar capacitor has been described. However, a tantalum electrolytic capacitor having a small size and a large capacity may be used instead.

  DESCRIPTION OF SYMBOLS 1 ... DC circuit, 10 ... Circuit breaker, 11 ... Main contact, 12 ... Auxiliary contact, 13 ... Coil, 14 ... Capacitor part, 15a, 15b ... Aluminum electrolytic capacitor (polar capacitor), 16a, 16b ... Diode, A ... arc

Claims (2)

A main contact inserted into a DC circuit between a DC power supply and a load, a coil and a capacitor unit are connected in series, and a resonance circuit unit is connected in parallel to the main contact. When opening the pole, the oscillating current generated in the resonance circuit unit due to the arc voltage characteristic of the main contact is superimposed on the direct current flowing through the main contact, and a zero point is generated in the current flowing through the main contact to cut off the current. A circuit breaker,
The capacitor unit has two sets of circuits in which a polar capacitor and a diode are connected in parallel so that a positive electrode of the polar capacitor and a cathode of the diode are connected,
A circuit breaker characterized in that the two sets of circuits are connected in series so that the same poles of the polarized capacitors are connected to each other.   The circuit breaker according to claim 1, wherein the polar capacitor is an aluminum electrolytic capacitor.

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