JP5832254B2 - Power supply circuit and earth leakage circuit breaker using the power supply circuit - Google Patents

Description

  The present invention relates to a power supply circuit built in a leakage breaker connected to an AC circuit, and a leakage breaker using the power supply circuit.

A power supply circuit built in this type of earth leakage circuit breaker converts an AC voltage (for example, AC100V, 200V, 440V, etc.) supplied from an AC circuit into a DC voltage by a rectifier, and then reduces the rectified DC voltage Thus, it is converted into a low-voltage direct current voltage (for example, DC 24V) and supplied as a drive power to the leakage detection circuit and the tripping device.
In such a power supply circuit, a series regulator of a constant voltage system or a constant current system is often used as a step-down means so as to be able to handle a wide range of input voltages while suppressing power loss (for example, Patent Document 1 and Patent Document 1). 2).

  In addition, the earth leakage breaker has an earth leakage trip device that opens the switching contact when an earth leakage occurs in the AC circuit, and a test function to periodically check whether the earth leakage detection and earth leakage trip function functions normally However, the power consumed by these is also supplied directly from the output voltage of the constant voltage power supply or constant current power supply or via a constant voltage power supply that is a series regulator (see, for example, Patent Document 3 and Patent Document 4). .)

Japanese Patent Publication No. 7-57062 (FIG. 1 and its explanation) Japanese Patent Laying-Open No. 2009-95125 (FIG. 1 and description thereof) Japanese Patent Laying-Open No. 2005-137095 (FIG. 1 and description thereof) Japanese Patent Laying-Open No. 2006-302601 (FIG. 2 and description thereof)

  As described above, in the power supply circuit of a conventional earth leakage breaker, the total current consumption of the earth leakage detection circuit and the current consumption of the earth leakage trip device and the test function is the constant regulator or constant current series regulator after rectification. Therefore, it is necessary to increase the power supply capacity of this series regulator. On the contrary, if the power supply capacity cannot be increased due to the volume restriction of this series regulator or the heat generation problem due to loss, it is necessary to remove the leakage current. It is necessary to suppress the power supply to the apparatus and the test function, and there has been a problem that it is not possible to ensure the necessary driving force and test current of the leakage tripping apparatus.

  Moreover, as a solution to this problem, it was considered to use an efficient switching regulator for the step-down means after rectification, but when the voltage of the AC circuit is high, for example, when considering use in an AC 440V AC circuit, Since the voltage after rectification exceeds 600V, the switching element used in the switching regulator must have a high withstand voltage and capable of high-speed switching. In addition to being difficult to obtain because it is not produced, a large drive current is required for the switching element in order to switch a high voltage at high speed. In some cases, a drive current exceeding the load current is consumed. Therefore, the loss due to switching (switching loss) is large and No effect is obtained to use the Tsu quenching regulator.

In addition, when the high voltage after rectification is switched at high speed by the switching regulator,
Propagation of switching noise to the AC circuit is inevitable, and problems such as radio interference may occur. For this reason, noise countermeasure parts and circuits that absorb noise are added, or means that intentionally dull the switching waveform to reduce noise generation itself are used, but adding noise countermeasure parts or the like increases the circuit scale. In addition, the countermeasure for dulling the switching waveform increases the switching loss, so that the effect of using the switching regulator cannot be obtained.

  The present invention has been made to solve the above-described problems, and the internal power consumed inside the circuit breaker is limited to the power supply from the series regulator in a steady state, and only in a non-steady state such as a test operation or a leakage operation. An object of the present invention is to obtain a power circuit and an earth leakage circuit breaker that are reduced in size and power consumption by suppressing power consumption during non-steady state by supplying power using a switching regulator. It is.

A leakage breaker according to the present invention includes a zero-phase current transformer that detects a leakage current of an AC circuit, a leakage detection circuit that determines a leakage based on a signal detected by the zero-phase current transformer, and the leakage detection circuit A trip coil that is energized by the output of the output, a trip device that opens an open / close contact provided in the AC circuit when the trip coil is energized, and a rectifier circuit connected to the AC circuit, a first step-down means is a series regulator which steps down the DC voltage supplied from the rectifier circuit, and a second step-down means is a switching regulator that steps down the DC voltage supplied from the first step-down unit, the The leakage detection circuit is supplied with power from the first step-down means, and the tripping coil is supplied with power from the second step-down means .

An earth leakage breaker according to the present invention includes: a zero-phase current transformer that detects an earth leakage current of an AC circuit; an earth leakage detection circuit that determines an earth leakage based on a signal detected by the zero-phase current transformer; and A trip coil that is energized by an output, a trip device that opens an open / close contact provided in the AC circuit when the trip coil is energized, a rectifier circuit connected to the AC circuit, comprising a first step-down means is a series regulator which steps down the DC voltage supplied from the rectifier circuit, and a second step-down means is a switching regulator that steps down the first DC voltage supplied from step-down transforming means, the The leakage detecting circuit is supplied with power from the first step-down means, and the tripping coil is supplied with power from the second step-down means. For a tripping coil that supplies a voltage that has been stepped down by a series regulator) to the leakage detection circuit and that only temporarily operates, a voltage that has been stepped down by the first step-down means is further reduced by a second step-down means (switching regulator). Since the power is supplied by stepping down, the load current of the first step-down means, which is a series regulator that has inevitably caused a large power loss due to a large drop voltage, can be reduced, and the power supply for the earth leakage breaker The entire circuit can be downsized and heat generation can be suppressed.

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

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to FIG. FIG. 1 is a block diagram showing a configuration of an earth leakage breaker using a power supply circuit according to Embodiment 1 of the present invention.
In FIG. 1, an earth leakage breaker 100 is connected to an open / close contact 2 that opens and closes an AC circuit and a zero-phase current transformer 3 inserted in the AC circuit 1, and a secondary winding 3 a of the zero-phase current transformer 3. Leakage detection circuit 4 for detecting a leakage based on an output signal from, a tripping coil 6 energized via switching means 5 by the output signal of this leakage detection circuit 4, and energization of this tripping coil 6 Sometimes the tripping device 7 that opens and closes the switching contact 2 constitutes a circuit breaker breaker and leakage detection function.

  The earth leakage breaker 100 includes a test switch 8 for a user to test the earth leakage function. When the test switch 8 is turned on, power is supplied to the test circuit 9 that generates a test current. The test circuit 9 outputs a pulse signal having the same frequency as that of the AC circuit 1 to the switching means 10, so that the test leakage current adjusted to a predetermined current value by the limiting resistor 11 from the internal power supply of the leakage breaker is zero. It is configured to flow through a tertiary winding 3 b provided in the phase current transformer 3.

  Further, the test current that excites the tertiary winding 3b in conjunction with the output of the leakage detection circuit 4, the tripping coil 6, the test circuit 9, and the test circuit 9 requires electrical energy for operating each of them. The electric energy is generated on the basis of the full-wave rectified DC voltage V1 supplied to the full-wave rectifier circuit 13 via the current limiting resistor 12 connected to each phase of the AC circuit 1. The current limiting resistor 12 prevents an excessive current from flowing into the full-wave rectifier circuit 13 and protects internal circuits after the full-wave rectifier circuit 13 when a high voltage such as a lightning surge is applied to the AC circuit 1. Resistance.

  The full-wave rectified DC voltage V1 is a high voltage obtained by full-wave rectification of the AC circuit 1 although the voltage is slightly lowered by the current limiting resistor 12, and is supplied by the first series regulator 14 which is a voltage step-down means. The voltage is stepped down to an intermediate predetermined voltage, and a DC voltage V2 in which ripple is suppressed by the smoothing capacitor 15 is generated. Further, the DC voltage V2 is stepped down and stabilized to a DC voltage V3 of about 5V by the second series regulator 16 which is a voltage step-down means. This DC voltage V3 is a power source for the leakage detection circuit 4 and the test circuit 9. Used as. Furthermore, the direct current voltage V2 is stepped down to the direct current voltage V4 by the first switching regulator 17 which is a voltage step-down means, and the direct current voltage V4 is supplied to the tripping coil 6 and the zero-phase current transformer 3. It is used as a power source for a test current for exciting the next winding 3b.

Next, a description will be given of the power loss in each of the steady state of the leakage breaker, the leakage trip, and the test operation.
First, in the steady state of the leakage breaker, the tripping coil 6 and the test function are not activated, and only the leakage detection circuit 4 is activated. In FIG. 1, the current consumption Ia of the leakage detection circuit 4 is The load currents of the first series regulator 14 and the second series regulator 16 are used as they are.
Normally, the relationship between the input current and output current of the series regulator is input current> output current because there is some loss in the series regulator, but here the loss is assumed to be so small that input current ≒ output current If so, Ia≈Ib≈Ic≈Id = Ie.

  Since the loss of the series regulator is the product of the potential difference between the input voltage and the output voltage and the load current, the loss P1 of the first series regulator 14 is P1 = (V1−V2) · Ia, the loss of the second series regulator 16 P2 is P2 = (V2-V3) · Ia.

Let's apply specific numbers to this. If the DC voltage V1 is 400V, the DC voltage V2 is 40V, the DC voltage V3 is 5V, and the current consumption Ia of the leakage detection circuit 4 is 1 mA, the loss P1 of the first series regulator 14 is
P1 = (V1-V2) * Ia = (400-40) * 0.001 = 0.36W,
The loss P2 of the second series regulator 16 is
P2 = (V2-V3) * Ia = (40-5) * 0.001 = 0.035W,
It becomes.

Next, the power loss at the time of tripping the earth leakage circuit breaker will be described.
At the time of current leakage tripping, a current If for driving the tripping coil 6 is supplied from the first switching regulator 17. Here, if the test operation is not performed, the current Ij = 0, and the output current Ih = If of the first switching regulator 17.

Here, if the efficiency of the first switching regulator 17 is α,
The input current Ig of the first switching regulator 17 is expressed as Ig = V4 / V2 / α · If,
The loss P3 of the first switching regulator 17 is P3 = (V2-V4) · Ig · (1-α)
= (V2-V4) .V4 / V2 / .alpha..If. (1-.alpha.)
It becomes.
The loss P1 of the first series regulator 14 is
P1 = (V1-V2) · Ib
= (V1-V2). (Ig + Id)
= (V1-V2). (Ia + V4 / V2 / .alpha..If)
And
If the drive current If of the tripping coil 6 is 40 mA and the efficiency α of the first switching regulator 17 is 0.8,
The loss P3 of the first switching regulator 17 is
P3 = (V2-V4) .V4 / V2 / .alpha..If. (1-.alpha.)
= (40-20) .40 / 20 / 0.8.0.04. (1-0.8)
= 0.1W
The loss P1 of the first series regulator 14 is
P1 = (V1-V2). (Ia + V4 / V2 / α.If)
= (400-40). (0.001 + 20/40 / 0.8.0.04)
= 9.36W
It becomes. The loss P2 of the second series regulator 16 is the same as that in the steady state, so P2 = 0.035W.

As described above, since the drive current If of the tripping coil 6 flows through the first series regulator 14 at the time of leakage trip, which is very large compared to the current consumption Ia of the leakage detection circuit 4 that is always operating, the first series regulator 14 is short. Although it is time, the loss P1 of the first series regulator 14 is relatively large.
However, compared with the conventional case, the first switching regulator 17 is not conventionally provided, and the driving current If of the tripping coil 6 is directly the load current of the first series regulator 14, so that the first series regulator The loss P1 of 14 was even larger.

In the conventional case, when the output voltage V2 of the first series regulator 14 is 20 V and the loss P1 is obtained,
P1 = (V1-V2). (Ia + If)
= (400-20). (0.001 + 0.04)
= 15.58W
It becomes.

  Thus, in the earth leakage breaker of the present invention, the loss of the first series regulator 14 at the time of tripping the earth leakage can be greatly reduced. Therefore, the capacity of the first series regulator 14 can be reduced and the trip coil can be reversed. It is possible to increase the driving current of 6 to improve the driving capability.

Next, the power loss during the test operation of the earth leakage breaker will be described.
During the test operation, when the test switch 8 is turned on, power is supplied from the output voltage V3 of the second series regulator 14 to the test circuit 9 that generates the test signal, and is driven by the pulse signal output from the test circuit 9. When the switching means 10 is switched, the test current flows from the output voltage V4 of the first switching regulator 17 to the tertiary winding 3b provided in the zero-phase current transformer 3 via the limiting resistor 11. Therefore, the power consumed at this time is the consumption current Ii of the test circuit 9 and the test current Ij flowing through the tertiary winding 3b.

  The test circuit 9 is composed of small-signal logic, and the current consumption Ii is not so large as about 1 mA, but the test current Ij is a test simulation current itself, and the required current is as follows. It is proportional to the rated sensitivity current of the earth leakage breaker and inversely proportional to the number N of turns of the tertiary winding 3b. Therefore, when the zero-phase current transformer 3 is large and the winding space of the tertiary winding can be sufficiently secured, the test current Ij can be suppressed by increasing the number N of turns of the tertiary winding 3b. When the zero-phase current transformer 3 is used, the space is small and the number of turns of the tertiary winding 3b is often limited, and the test current Ij is several tens of the same as the drive current If of the trip coil 6 described above. It is necessary to secure a current of about mA.

The power loss during the test operation will be described in the same manner as during the leakage trip.
First, since the output current Ie of the first series regulator 14 is the sum of the leakage detection circuit 4 and the test circuit 9,
Ie = Id = Ia + Ii
It becomes.
Further, the first switching regulator 17 is controlled so that the test current is stopped simultaneously with the start of the leakage tripping, so that the output current Ih of the first switching regulator 17 during the test operation is equal to the test current Ij. equally,
Ih = Ij
It becomes.

Here, if the efficiency of the first switching regulator 17 is α, the input current Ig of the first switching regulator 17 is
Ig = V4 / V2 / α · Ij
The loss P3 of the first switching regulator 17 is P3 = (V2−V4) · Ig · (1−α)
= (V2-V4) .V4 / V2 / .alpha..Ij. (1-.alpha.)
However, this equation is equivalent to the case where the drive current If of the trip coil 6 in the equation in the case of leakage trip is replaced with the test current Ij. Therefore, if the test current Ij is tripped and set to the same level as the drive current If of the coil 6,
The loss P3 of the first switching regulator 17 is
P3 = (V2-V4) .V4 / V2 / .alpha..Ij. (1-.alpha.)
= (40-20) .40 / 20 / 0.8.0.04. (1-0.8)
= 0.1W
Further, the loss P1 of the first series regulator 14 is obtained when the current consumption Ii of the test circuit 9 is 1 mA.
P1 = (V1-V2). (Ia + Ii + V4 / V2 / .alpha..If)
= (400-40). (0.001 + 0.001 + 20/40 / 0.8.0.04)
= 9.75W
Then, although it slightly increases by the consumption current of the test circuit 9, the loss is almost equal to that in the case of leakage trip.

Here, in the test function of the conventional earth leakage breaker, since the test current is supplied from the output voltage V2 of the first series regulator 14, the output of the first series regulator 14 is the same as in the case of tripping the earth leakage. When the voltage V2 is 20V and the loss P1 is obtained,
P1 = (V1-V2). (Ia + Ii + Ij)
= (400-20). (0.001 + 0.001 + 0.04)
= 15.96W
Therefore, even in the test operation, the leakage breaker of the present invention has less power loss.

  Note that the output voltage V2 of the first series regulator 14 can be more easily used when the voltage is set higher, and at the same time, the burden on the first series regulator 14 can be reduced. When the output voltage V2 is set to a voltage exceeding 50V, it is necessary to select high-voltage components for the smoothing capacitor 15 and the first switching regulator 17, and a general-purpose small-signal electronic component that is inexpensive and readily available is used. When the output voltage V2 increases, the switching voltage of the first switching regulator 17 increases and switching noise is likely to occur, or the switching loss increases and the efficiency decreases. Therefore, it is desirable to set the output voltage V2 to about 40V.

  As described above, the leakage breaker using the power supply circuit according to the first embodiment of the present invention once drops the voltage to the intermediate voltage V2 by the first series regulator 14, and the voltage is applied to the circuit that operates constantly. The voltage V2 is further stepped down by the second switching regulator 17 and the voltage V2 is further stepped down by the first switching regulator 17 for a circuit that operates only temporarily such as leakage trip or test operation. Since the power supply is supplied, the load current of the first series regulator 14 inevitably resulting in a large power loss due to the large drop voltage can be reduced, and the entire power supply circuit can be reduced in size and heat generated. Can be suppressed.

  Further, since there is a margin in the power supply capability with respect to the driving current If and the test current Ij of the tripping coil 6, the driving current If of the coil 6 is increased to increase the operating force, or the test current Ij is increased to 3 It is also possible to reduce the number of turns of the next winding 3b and reduce the cost.

  Conventionally, the switching regulator cannot be used because of the problem of the generation of switching noise and switching loss. However, as in the present invention, the first voltage is relatively low via the first series regulator 14. By operating the switching regulator 17, switching noise and switching loss can be suppressed, and the efficiency of the power supply circuit can be increased.

  Furthermore, by using the first switching regulator 17 only during non-stationary conditions such as leakage trip and test operation, even if the first switching regulator generates switching noise temporarily, the circuit breaker operates temporarily. Therefore, the adverse effect of noise can be minimized.

Embodiment 2. FIG.
A second embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a circuit diagram showing an earth leakage circuit breaker using the power supply circuit according to the second embodiment.
In the present embodiment, the loss during the test operation of the earth leakage circuit breaker using the power supply circuit shown in the first embodiment is further reduced. In FIG. 2, reference numeral 18 denotes a second switching regulator which is a voltage step-down means for outputting a very low voltage (for example, 1 V or less), and switching which operates in conjunction with the output pulse of the test circuit 9 is provided on the input side. The output voltage V4 of the first switching regulator 17 is connected by the means 10, and the output voltage V5 is such that the current Ik flows through the tertiary winding 3b of the zero-phase current transformer 3 via the limiting resistor 11. It is configured.

  In the example of the earth leakage breaker shown in the first embodiment, the limiting resistor 11 for setting the test current to a predetermined value in the test operation loses a lot of power, and if compared with the conventional earth leakage breaker, Although improved, the test operation only requires an exciting current to flow through the tertiary winding 3b, so the loss of the limiting resistor 11 cannot be said to be efficient.

  Therefore, in the present embodiment, the switching means 10 that operates in conjunction with the output pulse of the test circuit 9 can increase the excitation current to the tertiary winding 3b while reducing the loss of the limiting resistor 11. The current Ij flowing from the voltage V4 is stepped down to a very low voltage by the second switching regulator 18, so that a large excitation current flows through the tertiary winding 3b while reducing the loss of the limiting resistor 11. Yes.

  Since the second switching regulator 18 functions as a so-called current amplification, a constant current output type switching regulator may be used as the second switching regulator 18, and in that case, the limiting resistor 11 is omitted. .

  In recent years, with the widespread use of small portable devices, many DC-DC converters that have been made into one chip centering on those of less than 5V have been developed and supplied at low cost. It is also possible to use the DC-DC converter that has been made as the second switching regulator 18, and further miniaturization and higher efficiency can be expected.

  In many cases, such a one-chip DC-DC converter can input a voltage that is not so high. However, when such a DC-DC converter is used as the second switching regulator 18, the efficiency is slightly higher. However, the voltage input via the switching means 10 may be the output voltage V3 of the first series regulator having a low voltage instead of the voltage V4.

  In this way, by using the second switching regulator 18 to generate the test signal, the maximum load current of the first series regulator 14 is reduced, so that the power circuit can be downsized and the current consumption of the entire circuit breaker can be reduced. The effect can be expected.

  Further, since the exciting current to the tertiary winding 3b, that is, the current that can be passed as the test current is greatly expanded, the number of turns of the tertiary winding 3b can be greatly reduced. The third winding 3b itself provided in the first phase current transformer 3 can be accommodated outside the zero phase current transformer 3 with a number of turns of about several turns with an electric wire, so the third winding inside the zero phase current transformer 3 is not required. Thus, the cost and size of the zero-phase current transformer 3 can be reduced.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a circuit diagram showing a leakage breaker using the power supply circuit according to the third embodiment.
In the present embodiment, the second switching regulator 18 shown in the second embodiment is used as a constant current output, thereby efficiently generating a test current during a test operation of the leakage breaker and further reducing the loss. is there.

  In FIG. 3, the second switching regulator 18 is a circuit that generates a test current as in the second embodiment. However, the second switching regulator 18 is a constant current output whose output is constant at a predetermined current. The limiting resistor 11 for limiting the above is omitted. Further, since the efficiency of the second switching regulator 18 is improved by increasing the input voltage and increasing the voltage ratio between the input and the output, it is input to the second switching regulator 18 via the switching means 10. The input voltage is the output voltage V2 of the first series regulator 14, which is different from the second embodiment.

In the second switching regulator 18 according to the third embodiment, the switching element Q1, the inductor L1 serving as the output terminal of the second switching regulator 18, the flywheel diode D1 for the inductor, and the output terminal of the second switching regulator 18 are used. Is a self-excited step-down chopper type switching circuit based on a circuit having a photocoupler PC1 that detects the output level and performs feedback control on the switching element Q1 side. The transistor Q2 and the resistors R2, R3, and R4 are components of a gate circuit for controlling the switching element Q1 on and off according to the output of the photocoupler PC1.

Next, the operation of the second switching regulator 18 in the third embodiment will be described. The voltage of the output voltage V2 of the first series regulator 14 is intermittently supplied to the second switching regulator 18 at the same frequency as the AC circuit 1 by the switching means 10 that operates in conjunction with the output pulse of the test circuit 9. The
When the voltage of the output voltage V2 is supplied to the second switching regulator 18 in the initial state, a base current flows from the resistor R4 to the transistor Q2, the transistor Q2 is turned on, and the P-channel switching element Q1 is turned on via the resistor R3. Is turned on, and the current Ik begins to flow to GND through the resistor R1 connected in parallel from the inductor L1, the input side light emitting diode of the photocoupler PC1, and the tertiary winding 3b of the zero-phase current transformer 3. The current Ik increases linearly at a constant speed due to the inductance component of the inductor L1.

  Here, when the current Ik is small and the voltage across the resistor R1 (that is, the resistance value of the resistor R1 × the current Ik) is smaller than the forward voltage VF of the input side light emitting diode of the photocoupler PC1, the current Ik is the current of the photocoupler PC1. The output transistor of the photocoupler PC1 is in an off state without flowing through the input side light emitting diode.

When the current Ik increases and the voltage across the resistor R1 reaches the forward voltage VF of the input side light emitting diode of the photocoupler PC1, a part of the current Ik flows to the input side light emitting diode, and the output transistor of the photocoupler PC1 Turns on.
When the output transistor of the photocoupler PC1 is turned on, the transistor Q2 is turned off, the switching element Q1 is also turned off, and the current supply to the inductor L1 is stopped. However, since the current Ik tries to continuously flow through the diode D1 due to the energy stored in the inductance component of the inductor L1, the current Ik continues to flow while decreasing at a constant speed.

  When the current Ik decreases and the voltage across the resistor R1 becomes lower than the forward voltage VF of the input side light emitting diode of the photocoupler PC1, the output transistor of the photocoupler PC1 returns to the off state, and this operation is repeated thereafter. As a result, the second switching regulator 18 operates as a constant current switching regulator that maintains the current Ik at a constant level. Although this switching operation is restricted by the response speed of the photocoupler PC1, it can be arbitrarily set by the current Ik and the inductor L1, and the ripple is suppressed by setting the switching frequency as high as several hundred kHz. L1 can also be reduced.

  The above is the switching operation principle of the second switching regulator 18 in the third embodiment. In the second switching regulator 18 in the third embodiment, the load on the output side is the resistor R1 connected in parallel. And the input side light emitting diode of the photocoupler PC1 and the DC resistance of the inductor L. If the DC resistance of the inductor L is kept low, the output side voltage is about the forward voltage (about 1V) of the input side light emitting diode. Thus, it is possible to suppress the loss with a very simple circuit.

  Further, since the second switching regulator 18 in the third embodiment is a very simple circuit, it can be configured with general-purpose discrete components, and the above-described one-chip DC-DC centered on a working voltage of 5 V or less. The input voltage can be set higher than when a converter is used, and a larger output current, that is, a test current can be obtained.

  The series regulator and the switching regulator in the first and second embodiments of the present invention described above are widely known techniques, and the series regulator is a voltage step-down circuit in which a voltage control element is connected in series with a load. The switching regulator is a generic term for a DC stabilized power supply that controls the output voltage in a switching manner, and the input voltage can be switched at high speed by turning on / off the semiconductor switch. Thus, the output voltage is controlled.

  The above-described chopper type switching circuit according to the third embodiment of the present invention is also a widely known technique, and includes a switching element, an inductor serving as an output terminal of the chopper type switching circuit, a flywheel diode for the inductor, and a chopper type. It is a general term for non-insulated switching regulators composed of a feedback circuit that detects the output level of the inductor that is the output terminal of the switching circuit and controls the switching of the switching element. Among them, the feedback circuit has an appropriate hysteresis and time delay. A self-excited chopper type switching circuit that directly controls the switching period of the switching element is a circuit widely known as a basic circuit of a switching power supply.

As described above, the first and second embodiments and the third embodiment of the present invention have the following technical features.
Characteristic 1: Rectifying means 13 for converting an AC voltage supplied from the AC power source 1 into a DC voltage, a first step-down means 14 for stepping down the output voltage of the rectifying means, and an output voltage of the first step-down means A second step-down means 17 for further stepping down the voltage, wherein the first step-down means comprises a series regulator and the second step-down means comprises a switching regulator, and the switching regulator serving as the second step-down means comprises: The test circuit 9 can be operated only in a non-stationary condition that satisfies a predetermined condition such as an operation test, or a load such as the tertiary winding 3b and the limiting resistor 11 is connected only in a non-stationary condition that satisfies a predetermined condition. As a result, the switching operation of the switching regulator as the second step-down means is in a stopped state or a no-load state in a steady state such as during a non-test. Than is.
Feature 2: A rectifier circuit 13 that converts an AC voltage supplied from the AC circuit 1 into a DC voltage V1, and a first series regulator 14 that is a voltage step-down means that converts the DC voltage V1 into an intermediate voltage DC voltage V2. A second series regulator 16 which is a voltage step-down means for supplying power to a leakage detection circuit which is always operated by further stepping down the DC voltage V2 to the DC voltage V3, and further stepping down the DC voltage V2 to the DC voltage V4. A tripping coil 6 that operates unsteadily and consumes a large amount of power temporarily, and a first switching regulator 17 that is a voltage step-down means for supplying power to the test function units 3b, 10 and 11. The switching regulator 17 is used only during the earth leakage trip operation or during the test operation, and in the steady state other than during the earth leakage trip operation or the test operation. Is intended only to secure the internal power supply fault interrupter 100 by chromatography's regulators 14 and 16, the magnitude of the relationship between the DC voltage V1-V4, it is obtained by the V1>V2>V4> V3,.
Feature 3: Rectifying means 13 for converting an AC voltage supplied from the AC power supply 1 into a DC voltage, a first step-down means 14 for stepping down the output voltage of the rectifying means, and a step-down voltage by the first step-down means. Second step-down means 17 for further stepping down the output voltage is provided, wherein the first step-down means is constituted by a series regulator and the second step-down means is constituted by a switching regulator, respectively, and the first step-down means and the second step-down means Each output voltage of the step-down means is used as a power source.
Feature point 4: In the power supply circuit of feature point 3, the switching regulator 17, which is the second step-down means, is operated only in an unsteady state satisfying a predetermined condition or only in an unsteady state satisfying a predetermined condition. When the load is connected, the switching operation of the switching regulator 17 serving as the second step-down means is maintained in a stopped state or a no-load state in a steady state.
Feature 5: Zero-phase current transformer 3 that detects a leakage current in circuit 1, a leakage detection circuit 4 that determines leakage based on a signal detected by the zero-phase current transformer, and the circuit based on the output of the leakage detection circuit Provided with tripping devices 6 and 7 for opening the switching contact 2 provided in the above, and test function units 3b, 8, 9, 10, and 11 for testing the function of leakage detection, and the power source of the feature point 3 or the feature point 4 An earth leakage circuit breaker that supplies power from the circuit to the earth leakage detection circuit, the trip device, and the test function unit.
Feature point 6: In the earth leakage breaker of feature point 5, the output voltage of the switching regulator 17 whose power supply to the trip devices 6, 7 or the test function units 3b, 10, 11 is the second step-down means. Is an earth leakage circuit breaker.
Feature 7: In the earth leakage breaker of feature 5, the test function unit generates a pulse having the same frequency as the AC circuit based on the AC component of the AC circuit, or a frequency close to the frequency of the AC circuit. A test circuit 9 including an output oscillation circuit and a pulse signal output from the test circuit are input to the third winding 3b of the zero-phase current transformer 3 by stepping down to a voltage lower than the power supply voltage of the test circuit. A third step-down means 18 for supplying power via the limiting resistor 11 is provided, and the third step-down means 18 is a leakage breaker that is a switching regulator.
Feature 8: The earth leakage circuit breaker according to feature 7, wherein the switching regulator 18 as the third step-down means is a constant current output type switching regulator.
Feature point 9: In the earth leakage breaker of feature point 8, as the switching regulator 18 serving as the third step-down means, at least the switching element Q1, the inductor L1 serving as the output terminal of the switching regulator, and the flywheel for the inductor L1 A self-excited step-down chopper type switching circuit using a diode D1 and a photocoupler PC1 that detects the output level of the inductor L1 and performs feedback control on the switching element Q1 side. By connecting to the GND level via the input side light emitting diode of the photocoupler PC1 to which the shunt resistor R1 is connected in parallel from the inductor L1 at the end and the tertiary winding 3b of the zero-phase current transformer 3, Zero phase in time The test current Ik flowing to 3 winding 3b of Nagareki 3 is a earth leakage breaker and a predetermined amplitude level.

In the present invention, each embodiment can be appropriately modified or omitted within the scope of the invention.
In addition, in each figure, the same code | symbol shows the same or an equivalent part.

1 AC circuit, 2 Open / close contact, 3 Zero-phase current transformer,
3a Secondary winding of the zero phase current transformer 3, 3b Tertiary winding of the zero phase current transformer 3,
4 earth leakage detection circuit, 5 switching means, 6 trip coil,
7 trip device, 8 test switch, 9 test circuit,
10 switching means, 11 limiting resistance, 12 current limiting resistance,
13 full wave rectifier circuit, 14 first series regulator,
15 smoothing capacitor, 16 second series regulator,
17 a first switching regulator,
18 second switching regulator,
100 Earth leakage breaker.

Claims (6)

A zero-phase current transformer for detecting a leakage current in an AC circuit, a leakage detection circuit for determining a leakage based on a signal detected by the zero-phase current transformer, and a tripping activated by an output of the leakage detection circuit A coil, and a tripping device that opens an open / close contact provided in the AC circuit when the trip coil is energized, a rectifier circuit connected to the AC circuit, and a DC voltage supplied from the rectifier circuit comprising a first step-down means is a series regulator to step down, the second step-down means is a switching regulator that steps down the first DC voltage supplied from step-down transforming means, the a,
The earth leakage breaker is characterized in that the leakage detecting circuit is supplied with power from the first step-down means, and the tripping coil is supplied with power from the second step-down means . The earth leakage breaker according to claim 1, wherein a test function unit that tests a function of leakage detection by flowing a simulated earth leakage current to the zero-phase current transformer, and a test circuit that outputs a pulse signal to the test function unit; With
The earth leakage breaker characterized in that the simulated earth leakage current is supplied from the second step-down means . 3. The earth leakage breaker according to claim 2, wherein the test function unit outputs a circuit that generates a pulse having the same frequency as the AC circuit based on an AC component of the AC circuit or a frequency close to the frequency of the AC circuit. A third step-down means for stepping down the power supply voltage of the second step-down means to a voltage lower than the power supply voltage of the first step-down means, using the pulse signal output from the test circuit composed of an oscillation circuit as an input; And the third step-down means is a switching regulator . 4. The earth leakage circuit breaker according to claim 3, wherein the switching regulator as the third step-down means is a constant current output type switching regulator . The earth leakage breaker according to claim 4 ,
The switching regulator as the third step-down means includes a self-excited type having at least a switching element, an inductor serving as an output terminal of the switching regulator, and a photocoupler that detects an output level of the inductor and performs feedback control on the switching element side. The step-down chopper type switching circuit
The inductor serving as the output terminal of the step-down chopper type switching circuit is connected to the GND level through the input side light emitting diode of the photocoupler connected in parallel with the shunt resistor and the tertiary winding of the zero-phase current transformer. Thus , the earth leakage circuit breaker characterized in that the test current flowing in the tertiary winding of the zero-phase current transformer is set to a predetermined amplitude level during the test operation . 3. The earth leakage breaker according to claim 2 , wherein the test function unit outputs a circuit that generates a pulse having the same frequency as the AC circuit based on an AC component of the AC circuit or a frequency close to the frequency of the AC circuit. The pulse signal output from the test circuit composed of an oscillation circuit is input, the power supply voltage of the second step-down means is stepped down to a voltage lower than the power supply voltage of the first step-down means, and the zero-phase current transformer 3 through a limiting resistor to the primary winding comprises a third step-down means for supplying power, earth leakage breaker, which is a third step-down unit gas switch ing regulator.

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