JP2015170427A - Earth leakage circuit breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth leakage circuit breaker capable of applying a component with small driving current and heat output to a leakage detection circuit.SOLUTION: An earth leakage circuit breaker comprises: a switching contact 2 which opens and closes an AC electric path 1; a zero-phase current transformer 3 which detects zero-phase current of the AC electric path 1; an electric leakage detection circuit 4 which detects electric leakage on the basis of a detection signal of the zero-phase current transformer 3; a tripping device 6 driven by the electric leakage detection circuit 4; a capacitor drop power supply circuit 71 connected to the AC electric path 1; a first rectification circuit 72 which is connected to the subsequent stage of the capacitor drop power supply circuit 71 and supplies power to the electric leakage detection circuit 4; a second rectification circuit 75 connected to the AC electric path 1; and a self arc-extinguishing switching element 5 which is driven by the electric leakage detection circuit 4 and excites a tripping coil 6a of the tripping device 6. One end of the self arc-extinguishing switching element 5 is connected to the second rectification circuit 75. The tripping coil 6a is connected between the other end of the self arc-extinguishing switching element 5 and the negative electrode side of the second rectification circuit 75.

Description

  The present invention relates to an earth leakage circuit breaker that opens an electric circuit when a leakage current of the circuit becomes a predetermined value or more, and more particularly to an operation power source of the earth leakage circuit breaker.

  Most of the earth leakage breakers currently in circulation perform the level determination of the signal detected by the zero-phase current transformer by using the earth leakage detection circuit built in this earth leakage breaker, for example, an integrated circuit. If the signal level exceeds a predetermined value, the thyristor is turned on by the output from the leakage detection circuit, the built-in electromagnet device is driven to break the leakage breaker, and the electric circuit is opened. However, power is required for the operation of the leakage detection circuit and the electromagnet device, and this power is taken from the inside of the leakage breaker, for example, AC400V of the line voltage of the electric circuit, and a predetermined voltage, for example, DC12V. Is converted and supplied. At this time, in the three-pole earth leakage breaker, the outer two poles among the three poles (for convenience, the R phase, the S phase, and the T phase, that is, the S phase corresponds to the middle pole), that is, R− Generally, it is taken from the T phase. However, this is the reason for the restriction that limits the connection between the R and T phases when a three-pole earth leakage breaker is used for a single-phase circuit.

By the way, not only this earth leakage breaker but also internationalization of power distribution equipment, so-called global standardization has been said for a long time. Specifically, an earth leakage circuit breaker compliant with IEC (international standard) 60947-2 Annex B is required, but with JIS (Japanese Industrial Standard) C 821-2-2 Annex 2 (that is, Japanese original standard) One of the differences is that even if one phase of a three-phase circuit is lost, the leakage function must operate normally. Therefore, as described above, when the voltage is taken between the R and T phases, there is no problem with the S phase missing, but when the R or T phase is missing, the leakage function is immediately lost. .
In order to prevent the loss of this leakage function, it is known that the operating power is obtained from a three-phase power supply, that is, taken from each phase of the three-phase circuit, rectified by a rectifier circuit, and dropped to a predetermined voltage. ing. According to this method, even if a certain phase is lost, it is possible to generate operating power in the remaining two phases, so that the leakage function continues to operate normally. Further, when used in a single-phase circuit, there is a ripple effect that it is not always necessary to open the S phase, that is, it is possible to connect between the RS phase or the ST phase (for example, Patent Document 1). reference).

JP 2009-59607 A FIG.

  In the conventional earth leakage breaker, it is well known that the earth leakage breaker is interrupted by turning on the thyristor according to the output from the earth leakage detection circuit described above and driving the electromagnet device. The output needs to drive a thyristor with a large drive current. Accordingly, it is necessary to take measures such as increasing the heat generation of the leakage detection circuit and increasing the capacity of the capacitor used in the power supply circuit. In addition, when an inexpensive electromagnetic coil is used in the electromagnet device, the thyristor becomes a lead-type component rather than a surface-mount type, so that the substrate must be enlarged by using the lead-type thyristor.

  The present invention has been made in order to solve the above-described problems, and a leakage breaker that can be reduced in size by enabling application of a component that has a small drive current and a small amount of heat to the leakage detection circuit. Is what you get.

  An earth leakage circuit breaker according to the present invention includes an open / close contact that opens and closes an AC circuit, a zero-phase current transformer that detects a zero-phase current in the AC circuit, and the zero-phase current transformer. A leakage detection circuit for detecting a leakage based on the detection signal, a tripping device driven by the leakage detection circuit, a serial body connected to each phase of the AC circuit, and a resistor and a capacitor connected in series; A first rectifier circuit connected to the subsequent stage of the series body for supplying power to the leakage detection circuit, a second rectifier circuit connected to the AC circuit, and a subsequent stage of the second rectifier circuit for detecting leakage And a switching element that excites a tripping coil of the tripping device by being driven by a circuit, the switching element is a self-extinguishing type switching element, and one end of the switching element is And a tripping coil is connected between the other end of the switching element and the negative side of the second rectifier circuit.

  According to the present invention, it is possible to obtain a three-phase power supply leakage breaker that can use a small-sized component that generates a small amount of heat and that can be used for a harmonic circuit and a reverse connection circuit.

It is a circuit diagram which shows the 3 pole earth-leakage circuit breaker in Embodiment 1 of this invention. It is a circuit diagram which shows the 3-pole earth-leakage circuit breaker in Embodiment 2 of this invention.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a three-pole earth leakage breaker according to Embodiment 1 of the present invention.
In FIG. 1, a leakage breaker 101 includes an open / close contact 2 that opens and closes an AC circuit 1, a zero-phase current transformer 3 that is inserted into the AC circuit 1 and detects a zero-phase current in the AC circuit 1, and the zero An electric leakage detection circuit 4 connected to the phase current transformer 3 and detecting electric leakage based on the detection signal, a tripping device 6 driven by an output signal of the electric leakage detection circuit 4, and an electric leakage detection circuit 4 A self-extinguishing switching element 5 that excites the tripping coil 6 a of the tripping device 6, and a power supply circuit 7 that supplies power to both the leakage detection circuit 4 and the tripping device 6. .

The tripping device 6 includes a tripping coil 6a that is excited by conduction of the self-extinguishing type switching element 5, a tripping mechanism 6b that opens the switching contact 2 when the tripping coil 6a is excited, have.
The power supply circuit 7 converts an AC voltage input from the AC circuit 1 into a predetermined DC voltage, for example, DC 12 V, supplies an excitation current to the tripping coil 6 a and supplies power to the leakage detection circuit 4.
For the self-extinguishing type switching element 5, a MOSFET, IGBT or the like having a voltage control gate is used in order to suppress the output current from the leakage detection circuit 4.

  Details of the power supply circuit 7 will be described below. The power supply circuit 7 is connected to each phase of the AC circuit 1, and includes a capacitor drop power supply circuit 71 which is a series body including a current limiting resistor 71a for limiting current and a capacitor 71b connected in series to the current limiting resistor 71a. The first rectifier circuit 72 connected to the subsequent stage of the capacitor drop power supply circuit 71 and formed of a full diode bridge, and the cathode is connected to the positive electrode side of the output of the first rectifier circuit 72. And a smoothing capacitor 74 connected in parallel to both ends of the Zener diode 73.

The anode of the Zener diode 73 is connected to one end of the trip coil 6a, and the other end of the trip coil 6a is connected to the negative side of the output of the first rectifier circuit 72.
Furthermore, the power supply circuit 7 includes a second rectifier circuit 75 that is connected to the AC electric circuit 1 and generates a power supply for driving the tripping coil 6a. The second rectifier circuit 75 is obtained by full-wave rectifying any two of the three phases in the AC circuit 1.

  More specifically, the second rectifier circuit 75 has a diode 75a whose anode is connected to the R phase of the AC circuit 1, the cathode is connected to the drain of the self-extinguishing switching element 5, and the anode is the AC circuit 1. The diode 75b has a cathode connected to the cathode of the diode 75a, a cathode connected to the T phase of the AC circuit 1, and an anode connected to the negative side of the output of the first rectifier circuit 72. A diode 75c; and a diode 75d having a cathode connected to the S phase of the AC circuit 1 and an anode connected to the anode of the diode 75c.

  The power supply terminal 4a of the leakage detection circuit 4 is connected to the positive side of the output of the first rectifier circuit 72, and the ground 4b of the leakage detection circuit 4 is connected to the connection point of one end of the tripping coil 6a and the anode of the Zener diode 73. Is connected. The output port 4 c of the leakage detecting circuit 4 is connected to the gate of the self-extinguishing switching element 5 through the resistor 8. The source of the self-extinguishing switching element 5 is connected to a connection point between one end of the tripping coil 6 a and the anode of the Zener diode 73.

In addition, a resistor 9 is connected between the gate and source of the self-extinguishing switching element 5, and the voltage applied to the gate of the self-extinguishing switching element 5 is configured by the resistor 8 and the resistor 9. Is adjusted. Further, a capacitor 10 for preventing malfunction due to noise is connected between the gate and the source of the self-extinguishing switching element 5.
The “one end of the switching element” described in the claims refers to the drain of the self-extinguishing switching element 5 described above, and “the other end of the switching element” described in the claims. Is the source of the self-extinguishing switching element 5 described above.

Next, the operation of the power supply circuit 7 will be described.
In a normal state, when an AC voltage of about AC 100 V to 400 V is supplied from the R, S, and T phases of the AC circuit 1 (referred to as R, S, and T phases from the left in FIG. 1), a capacitor drop power supply circuit An alternating current flows through a series body composed of a current limiting resistor 71 a and a capacitor 71 b constituting 71, and is converted into DC power by the first rectifier circuit 72. The DC power output from the first rectifier circuit 72 is stepped down to a predetermined DC voltage, for example, DC12V, and smoothed by a Zener diode 73 and a capacitor 74 connected to the subsequent stage of the first rectifier circuit 72. This is supplied to the leakage detection circuit 4.

Next, the purpose of connecting the tripping coil 6a between the ground 4b of the leakage detection circuit 4 and the negative side of the first rectifier circuit 72 will be described.
Since the power supply circuit 7 employs the capacitor drop power supply circuit 71 that does not generate heat, the surge current corresponding to the high frequency flowing from the AC circuit 1 has a frequency f of 1 / 2πfC that is the impedance of the capacitor drop power supply circuit 71. Therefore, the voltage cannot be lowered. Here, C is the capacity of the capacitor 71 b, and f is the frequency of the surge current flowing from the AC circuit 1.

  Therefore, there is a problem of exposing the detection circuit and the constant voltage circuit in the leakage detection circuit 4 to an overload. In order to solve this, the surge current flowing from the AC circuit 1 is suppressed by using 2πfL which is the reactance of the tripping coil 6a. Thereby, the detection circuit and the constant voltage circuit in the leakage detection circuit 4 are protected from being overloaded. Here, L is the inductance of the tripping coil 6a.

  On the other hand, in order to drive the tripping device 6, the power supply voltage must be applied to the tripping coil 6a as it is without causing a voltage drop elsewhere. Therefore, the second rectifier circuit 75 connects the anode side of the diodes 75a and 75b to the R and S phases from the AC drop circuit 1 side from the capacitor drop power supply circuit 71, respectively, to the drain of the self-extinguishing switching element 5. The cathodes of the diodes 75a and 75b are connected.

  Further, the anode side of the diodes 75c and 75d is connected to one end of the tripping coil 6a, and the cathode side of the diodes 75c and 75d is connected to the S and T phases on the AC circuit 1 side from the capacitor drop power circuit 71. Each is connected. As a result, a circuit configuration that bypasses the capacitor drop power supply circuit 71 when a half-wave rectifier circuit that full-wave rectifies any two phases of the three phases of the AC circuit 1 and the self-extinguishing switching element 5 is turned on. Yes.

Next, the operation of earth leakage circuit breaker 101 will be described.
The power line of the AC circuit 1 is inserted into a zero-phase current transformer 3 disposed on the load side (upper and lower sides in FIG. 1) of the switching contact 2, and the zero-phase current transformer 3 has an AC circuit. When the balance of the current flowing through 1 is lost, that is, when a leakage current is generated from the AC circuit 1 to the ground, a signal proportional to the level is output.

  The signal from the zero-phase current transformer 3 is sent to the leakage detection circuit 4 via a voltage conversion circuit (not shown). In this leakage detection circuit 4, the peak voltage value of the transmitted signal or the width of the signal is determined, and when it is determined that they exceed a predetermined level, a signal is sent to the gate of the self-extinguishing switching element 5. By outputting, the drain-source of the self-extinguishing type switching element 5 becomes conductive. By this conduction, the tripping coil 6a is excited and the tripping mechanism 6b is driven to open the switching contact 2, thereby preventing a fire or personal injury due to leakage current.

  The leakage detection circuit 4 is constituted by an integrated circuit, and the supply of the gate signal of the self-extinguishing type switching element 5 from the leakage detection circuit 4 is such that the power supply side and the load side of the leakage breaker 101 are correctly connected. Regardless of the normal connection or the reverse connection in which the power supply side and the load side of the earth leakage breaker 101 are connected in reverse, the leakage current disappears and resets, and the drain-source between the self-extinguishing switching element 5 is Non-conducting. The excitation of the tripping coil 6a is stopped by the non-conduction between the drain and source of the self-extinguishing type switching element 5.

  Further, when the drain-source of the self-extinguishing switching element 5 becomes non-conductive, a surge voltage is generated between both ends of the tripping coil 6a. Therefore, in general, a flywheel diode is connected in parallel to both ends of the tripping coil 6a. However, in this embodiment, the tripping coil 6a → the diode constituting the first rectifier circuit 72 → the Zener diode 73 → Since the circuit of the tripping coil 6a functions as a flywheel diode, it is not necessary to provide a flywheel diode.

  According to the present embodiment, the capacitor drop power supply circuit 71 is connected to each phase of the AC circuit 1, and the resistor 71a and the capacitor 71b are connected in series, and the first connected to the subsequent stage of the capacitor drop power supply circuit 71. Rectifier circuit 72, a second rectifier circuit 75 connected to the AC circuit 1, and a self-extinguishing type connected to a subsequent stage of the second rectifier circuit 75 and exciting the tripping coil 6 a of the tripping device 6. A switching element 5, one end of the self-extinguishing type switching element 5 is connected to the positive side of the second rectifying circuit 75, and the negative side of the second rectifying circuit 75 and the self-extinguishing type switching element 5 Since the tripping coil 6a is connected to the other end, the current for the leakage detection circuit 4 to drive the self-extinguishing type switching element 5 is reduced, and the power supply circuit in the leakage breaker 101 is reduced. Heat generation in the path 7 can be suppressed. Furthermore, since the heat generation of the power supply circuit 7 in the earth leakage breaker 101 can be suppressed, a small and inexpensive earth leakage breaker can be obtained.

  In addition, a capacitor drop power supply circuit 71 that does not generate heat, a self-extinguishing switching element 5 having a voltage control gate to suppress the output current from the leakage detection circuit 4, and a half-wave rectifier circuit as a drive power supply for the trip coil 6a. Since a certain second rectifier circuit 75 is employed, the amount of heat generated by the power supply circuit 7 can be suppressed.

  One end of the self-extinguishing type switching element 5 is connected to the positive side of the second rectifier circuit 75, and between the negative side of the first rectifying circuit 72 and the other end of the self-extinguishing type switching element 5. Since the tripping coil is connected, the surge current flowing from the AC circuit 1 can be suppressed using 2πfL, which is the reactance of the tripping coil 6a.

  Further, since the tripping coil 6a is excited by the self-extinguishing switching element 5, the leakage detection circuit 4 is turned off even when the leakage breaker 101 is reversely connected to the power supply side and the load side. The excitation of the tripping coil 6a can be stopped, and burning of the tripping coil 6a can be prevented.

  Since the circuit of the trip coil 6a → the diode constituting the first rectifier circuit 72 → the Zener diode 73 → the trip coil 6a serves as a flywheel diode provided in parallel to the trip coil 6a, Separately, it is not necessary to provide a flywheel diode in the drive circuit of the tripping coil 6a, and the leakage breaker 101 can be downsized.

  Further, a stable DC power supply is supplied from the capacitor drop power supply circuit 71 that does not generate heat to the leakage detection circuit 4 via the first rectifier circuit 72 so that the surge current from the AC circuit 1 can be absorbed in any phase. Since the tripping coil 6a is connected in series with the capacitor drop power supply circuit 71, the tripping coil 6a is kept in a state in which the output current from the leakage detection circuit 4 is minimized in the event of a leakage accident no matter which phase is lost. And the leakage breaker 101 can be tripped.

Embodiment 2. FIG.
FIG. 2 is a circuit diagram showing a three-pole earth leakage breaker according to Embodiment 2 of the present invention.
Although IEC 60947-2 specifies that the operation is performed within 40 ms at 5 times the rated sensitivity current, in the first embodiment, the trip coil 6a is a second rectifier circuit 75 which is a half-wave rectifier circuit. Therefore, depending on the input phase, there is a possibility that the operation time of the tripping device 6 exceeds 40 ms.

  The earth leakage breaker 102 according to the present embodiment makes it possible to sufficiently shorten the operation time of the trip device 6 with respect to 40 ms. As shown in FIG. 2, the trip device 6 has a stable DC voltage. The second rectifier circuit 75, which is a half-wave rectifier circuit, is changed to a third rectifier circuit 76, which is a full-wave rectifier circuit. Since other configurations are the same as those of the first embodiment, detailed description thereof is omitted.

  In order to drive the tripping device 6, the power supply voltage must be applied to the tripping coil 6a as it is without causing a voltage drop elsewhere. Therefore, the third rectifier circuit 76 connects the anodes of the diodes 76a, 76b, and 76c from the capacitor drop power supply circuit 71 to all phases from the AC circuit 1 side, and the cathodes of the diodes 76a, 76b, and 76c are self-extinguishing switching. Connect to the drain of element 5.

  Also, the anodes of the diodes 76d, 76e, and 76f are connected to the other end of the tripping coil 6a, and the cathodes of the diodes 76d, 76e, and 76f are connected to all phases on the AC circuit 1 side from the capacitor drop power circuit 71, respectively. A full-wave rectifier circuit is configured. For this reason, when the self-extinguishing type switching element 5 is turned on, the capacitor drop power supply circuit 71 is bypassed and power is supplied.

  According to the present embodiment, the capacitor drop power supply circuit 71 connected to each phase of the AC circuit 1 and having a resistor and a capacitor connected in series, and the first rectification connected to the subsequent stage of the capacitor drop power supply circuit 71. A circuit 72, a third rectifier circuit 76 connected to the AC circuit 1, and a self-extinguishing switching element that is connected to a subsequent stage of the third rectifier circuit 76 and excites the trip coil 6 a of the trip device 6. 5, one end of the self-extinguishing type switching element 5 is connected to the positive side of the third rectifying circuit 76, and the other end of the self-extinguishing type switching element 5 is connected to the negative side of the third rectifying circuit 76. Since the tripping coil 6a is connected between the current leakage detection circuit 4 and the current leakage detection circuit 4 to drive the self-extinguishing type switching element 5, the current leakage circuit breaker 102 generates heat from the power supply circuit 7. Can be suppressed. Furthermore, since the heat generation of the power supply circuit 7 in the earth leakage breaker 102 can be suppressed, a small and inexpensive earth leakage breaker can be obtained.

  In addition, since the third rectifier circuit 76 that is a three-phase full-wave rectifier circuit is used, a stable DC voltage is always supplied to the tripping device 6, so that the interruption operation time of the earth leakage breaker 102 is defined by IEC60947-2. It can be sufficiently shorter than the predetermined value 40 msec.

  One end of the self-extinguishing switching element 5 is connected to the positive side of the third rectifier circuit 76, and between the negative side of the third rectifying circuit 76 and the other end of the self-extinguishing type switching element 5. Since the tripping coil 6a is connected, the surge current flowing from the AC circuit 1 can be suppressed using 2πfL, which is the reactance of the tripping coil 6a.

2 switching contacts, 3 zero-phase current transformer, 4 earth leakage detection circuit,
5 self-extinguishing switching element, 6 trip device, 7 power circuit,
71 capacitor drop power supply circuit, 72 first rectifier circuit,
73 Zener diode, 75 second rectifier circuit,
101 Earth leakage breaker.

Claims (3)

An open / close contact that opens and closes an AC circuit, a zero-phase current transformer that detects a zero-phase current in the AC circuit, and a zero-phase current transformer connected to the zero-phase current transformer, A leakage detection circuit to detect, a tripping device driven by this leakage detection circuit, a series body connected to each phase of the AC circuit, and a resistor and a capacitor connected in series, and connected to the subsequent stage of the series body A first rectifier circuit for supplying power to the leakage detection circuit, a second rectifier circuit connected to the AC circuit, and a second stage of the second rectifier circuit, and driven by the leakage detection circuit. A leakage breaker comprising a switching element that excites a tripping coil of the tripping device,
The switching element is a self-extinguishing type switching element, and one end of the switching element is connected to the second rectifier circuit, and between the other end of the switching element and the negative electrode side of the second rectifier circuit. An earth leakage circuit breaker, wherein the tripping coil is connected. 2. The leakage breaker according to claim 1, wherein the second rectifier circuit is obtained by full-wave rectifying any two of three phases. The earth leakage circuit breaker according to claim 1, wherein the second rectifier circuit is a full-wave rectifier of all three phases.

Images