JP2011250486A - Earth leakage breaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the quantity of magnetic shield disposition for the core of a zero-phase sequence current transformer having circular form or non-circular form and restrict the number of components as a whole.SOLUTION: An earth leakage breaker comprises: a zero-phase sequence current transformer including a core made of a ring-shaped magnetic material which lets a plurality of primary conductors forming an AC electric path pass through the inside thereof and a toroidal-shaped coil wound around the core; a leakage current determination section which, according to the output voltage detected by the zero-phase sequence current transformer, determines whether leakage current is flowing in the AC electric path; a balanced current determination section which, based on waveform information on the output voltage detected by the zero-phase sequence current transformer, determines whether conducting current in the AC electric path is balanced current; a leakage determination section which, according to the respective determination results from the leakage current determination and the balanced current determination sections, determines whether leakage has occurred in the AC electric path; and an opening/closing control section which, according to the determination result from the leakage determination section, opens or closes an electric path contact provided in the AC electric path.

Description

  The present invention relates to a leakage breaker that determines whether or not a leakage has occurred in an AC circuit according to a detection output of a zero-phase current transformer.

  The earth leakage breaker is composed of an annular core (core) made of a magnetic material such as a soft magnetic material that penetrates a plurality of primary conductors constituting an AC circuit, and a toroidal coil wound around the core. A zero-phase current transformer (ZCT) is provided, and it is determined whether or not a leakage has occurred in the plurality of primary conductors according to an output voltage that is a detection output at both ends of the coil of the zero-phase current transformer.

  When a leakage occurs in any of the primary conductors, a difference occurs between the current flowing in the forward direction of the AC circuit and the current flowing in the return direction, and a leakage current based on the difference is generated. Further, in the following description, when a leakage occurs in the AC circuit, the current generated based on the difference between the current flowing in the forward direction and the current flowing in the return direction of the primary conductor constituting the AC circuit is defined as a leakage current. Called. Furthermore, since the energization currents of the plurality of primary conductors are unbalanced as a whole, the state of the magnetic flux in the core of the zero-phase current transformer is changed by the magnetic flux generated by the leakage current. Thereby, the induced voltage corresponding to the leakage current is detected at both ends of the coil of the zero-phase current transformer.

  Further, when no leakage occurs in any of the primary conductors, a so-called equilibrium state in which the vector sum of the energization currents of the plurality of primary conductors is zero. In this equilibrium state, magnetic flux exists in the core of the zero-phase current transformer, but these magnetic fluxes cancel each other, and the induced voltage as described above is not detected by the zero-phase current transformer. Therefore, it is possible to determine whether or not a leakage current has occurred in the AC circuit by outputting the output voltage across the coil of the zero-phase current transformer as a detection output. Further, in the following description, when no leakage occurs in any of the primary conductors, the energizing current of each primary conductor when the vector sum of the energizing currents of the plurality of primary conductors becomes zero is the balanced current. Called.

  In reality, however, the uniformity of the magnetic flux inside the core is lost due to the influence of the position of each of the primary conductors, coil winding variations, or the shape of the core, and the coil of the zero-phase current transformer is in an equilibrium state. An induced voltage may be detected at both ends. In addition, when a load device such as a motor that flows inrush current is connected to the load side of the primary conductor, the induced voltage generated at both ends of the coil of the zero-phase current transformer is the output when the leakage current is detected. The voltage has an unnecessary output component equal to or higher than the voltage, and the leakage breaker may cause a false detection of a leakage.

  In order to prevent erroneous detection of leakage due to the reduction of such unnecessary output components, a structure in which a shield member made of a magnetic material is disposed around the core and the coil to shield an external magnetic field is generally employed. . As a zero-phase current transformer having such a structure that blocks an external magnetic field, there is, for example, Patent Document 1.

  Patent Document 1 discloses a zero-phase current transformer that covers a non-circular annular core with a primary conductor penetrating and winding a secondary coil with a layered magnetic shield, the magnetic shield having a multilayer structure, A zero-phase current transformer is disclosed in which a non-magnetic layer or air layer having a predetermined thickness is provided therebetween. According to Patent Document 1, it is possible to realize a zero-phase current transformer having improved shielding performance as compared with a single-layer magnetic shield having no nonmagnetic layer or air layer. Moreover, there exists patent document 2 as an earth-leakage circuit breaker using such a zero phase current transformer, for example.

  In Patent Document 2, a current transformer for detecting a phase current of the primary conductor is arranged for each of a plurality of primary conductors penetrating the coil, and the phase currents detected by the current transformer are combined. Only when the value exceeds a predetermined threshold value, it is determined as a ground fault, the output of the lock signal is canceled, the electromagnetic device is disconnected from the AC circuit, and when it is determined that the ground fault is not detected, the output of the lock signal is zero. An earth leakage breaker that locks an earth leakage current detected by a phase current transformer to prevent malfunction, and a ground fault detection method are disclosed. According to Patent Document 2, it is determined whether or not a ground fault has occurred when a transient phase current flows even in a single-phase or three-phase AC circuit, and malfunction or detection is prevented. be able to.

Japanese Patent Laid-Open No. 7-83960 JP 2000-31434 A

  However, in the zero-phase current transformer shown in Patent Document 1, an unnecessary output in the induced voltage (output voltage) generated at both ends of the coil of the zero-phase current transformer when, for example, a large balanced current flows in the AC circuit. Many magnetic shields are provided to reduce the components. For this reason, the material cost of the material constituting the magnetic shield is increased, and the coil for arranging the core provided with the magnetic shield is also enlarged, so that the zero-phase current transformer is enlarged as a whole. was there. Moreover, in the earth leakage breaker shown in patent document 2, it is necessary to provide the current transformer for detecting the phase current of each AC circuit separately, the number of parts increases as the whole earth leakage breaker, and the earth leakage breaker concerned There was also a problem that the manufacturing cost of the increased.

  Therefore, the present invention has been made in view of the above-described conventional circumstances, and can reduce the amount of magnetic shields to be disposed relative to the core of a zero-phase current transformer having a circular shape or a non-circular shape. It aims at providing the earth-leakage interrupting device which suppresses a score.

  In order to achieve the above-described object, the present invention is the above-described leakage breaker, in which a core made of an annular magnetic material that penetrates a plurality of primary conductors that form an AC circuit is wound around the core. A zero-phase current transformer including a rotated toroidal coil, and a leakage current determination unit that determines whether or not a leakage current is flowing in the AC circuit according to the output voltage detected by the zero-phase current transformer And, based on the waveform information of the output voltage detected by the zero-phase current transformer, an equilibrium current determination unit that determines whether the energization current of the AC circuit is an equilibrium current, a leakage current determination unit, and an equilibrium current determination In accordance with each determination result of the unit, an electric leakage determination unit that determines whether or not electric leakage has occurred in the AC electric circuit, and an electric circuit contact provided in the AC electric circuit according to the determination result determined by the electric leakage determination unit An open / close control unit that opens and closes. The features.

  Further, the present invention is the above-described ground fault interrupter, wherein the waveform information is a ratio of a peak value of the output voltage in a predetermined detection unit time to an average value of the output voltage in the detection unit time, and an equilibrium current. The determination unit determines that the energization current of the AC circuit is an equilibrium current when the value of the ratio is larger than a predetermined equilibrium current determination threshold.

  Further, the present invention is the above-described ground fault interrupter, wherein the waveform information is a ratio of a peak value of the output voltage in a predetermined detection unit time to an average value of the output voltage in the detection unit time, and an equilibrium current. The determination unit determines that the energization current of the AC circuit is an equilibrium current when the value of the ratio is larger than a predetermined equilibrium current determination threshold.

  Further, the present invention is the above-described ground fault interrupter, wherein the predetermined detection unit time is one cycle with respect to the power supply frequency of the AC power supply.

  Further, the present invention is the above-described ground fault interrupter, wherein the waveform information is the number of occurrences or polarity of a peak exceeding a predetermined other equilibrium current determination threshold in a predetermined detection unit time, or the occurrence frequency and polarity. Yes, the balanced current determination unit determines whether or not the energization current of the AC circuit is an equilibrium current according to the number of occurrences or polarity of the peak exceeding the other equilibrium current determination threshold, or the number of occurrences and polarity. Features.

  Further, the present invention is the above-described ground fault interrupter, wherein the balanced current determination unit is configured such that the energization current of the AC circuit is a balanced current when the number of occurrences of a peak is at least twice in a predetermined detection unit time. It is characterized by determining.

  Further, the present invention is the above-described leakage breaker, wherein the balanced current determination unit is configured such that when the polarity of the peak repeats at least twice continuously in a predetermined detection unit time, the energization current of the AC circuit is the balanced current. It is determined that it exists.

  Further, the present invention is the above-described leakage breaker, further comprising a zero-cross detection unit that detects a zero-cross of the energization current of the AC circuit, and the balanced current determination unit is configured such that the zero-cross of the energization current of the AC circuit is detected by the zero-cross detection unit. A predetermined time including the detected time point is set as a detection unit time, and it is determined whether or not the energization circuit of the AC circuit is a balanced current.

  Further, the present invention is the above-described ground fault interrupter, wherein an over-leakage current determination unit determines whether or not the over-leakage current is flowing in the AC circuit according to the output voltage detected by the zero-phase current transformer. The over-leakage current determination unit determines that the energization current of the AC circuit is an over-leakage current when the output voltage detected by the zero-phase current transformer exceeds a predetermined over-leakage current determination threshold. In addition, the leakage determination unit has priority over the determination results of the overcurrent leakage current determination unit over the determination results of the leakage current determination unit and the equilibrium current determination unit, and determines that excessive leakage has occurred in the AC circuit. To do.

  In addition, the present invention is the above-described leakage breaker, wherein the switching controller determines the electric circuit contact provided in the AC electric circuit when it is determined by the electric leakage determination unit that an excessive electric leakage has occurred in the AC electric circuit. It is characterized by opening.

  ADVANTAGE OF THE INVENTION According to this invention, the amount of arrangement | positioning of the magnetic shield with respect to the core of the zero phase current transformer which has each circular shape or non-circular shape can be reduced, and the number of parts as a whole can be restrained.

The circuit block diagram which shows the internal structure of the earth-leakage interrupter of 1st Embodiment Explanatory drawing which shows the relationship between the leakage current determination signal, the equilibrium current determination signal, the leakage determination signal, and the open / close state of the circuit contact Explanatory drawing explaining an example of operation | movement of the electric leakage determination part of the electric leakage interruption apparatus of 1st Embodiment, (a) Explanatory drawing in case the leakage current generate | occur | produces and the equilibrium current does not flow, (b) Leakage electric current generate | occur | produces In addition, an explanatory diagram when a balanced current flows An explanatory diagram showing the calculation result when the balanced current is energized and the calculation result when the leakage current is generated, (a) an explanatory diagram when the peak value / average value is calculated as the calculation result, (b) Explanatory drawing when the peak value / effective value is calculated as the calculation result An explanatory diagram showing a time change between the leakage current and the output voltage of the zero-phase current transformer, (a) an explanatory diagram showing a time change when the leakage current is 2 [A], and (b) a leakage current of 20 Explanatory diagram showing the time change when [A], (c) explanatory diagram showing the time change when the leakage current is 50 [A] An explanatory diagram showing a time change between the balanced current and the output voltage of the zero-phase current transformer, (a) an explanatory diagram showing a time change when the balanced current is 100 [A], and (b) an equilibrium current of 200 Explanatory diagram showing the time change when [A], (c) explanatory diagram showing the time change when the equilibrium current is 350 [A] An explanatory diagram showing the time change between the balanced current and the output voltage of the zero-phase current transformer, (a) an explanatory diagram showing the time change when the balanced current is 600 [A], and (b) the balanced current is 1100. Explanatory diagram showing the time change when [A], (c) explanatory diagram showing the time change when the equilibrium current is 1650 [A] The circuit block diagram which shows the internal structure of the earth-leakage interrupter of 2nd Embodiment Explanatory drawing explaining determination of the presence or absence of energization of the balance current of the balance current determination part in 2nd Embodiment Explanatory drawing which shows the relationship between the leakage current determination signal, the equilibrium current determination signal, the excessive leakage current determination signal, the leakage determination signal, and the open / close state of the circuit contact The flowchart explaining operation | movement of the balanced current determination part in 2nd Embodiment. Explanatory diagram showing the relationship between the average value of the output voltage of the zero-phase current transformer when the leakage current is generated and when the balanced current is applied The circuit block diagram which shows the internal structure of the earth-leakage interrupter in the modification of 2nd Embodiment

  Hereinafter, each embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
1. FIG. 1 is a circuit block diagram illustrating a circuit configuration of a ground fault interrupter 10 according to the first embodiment.

  As shown in FIG. 1, the leakage breaker 10 includes a zero-phase current transformer 12, a signal processing circuit 13, an A / D conversion circuit 14, and a leakage determination unit that pass through primary conductors 11R, 11S, and 11T. 18 and an opening / closing control unit 19. Hereinafter, each part 12-19 which comprises the earth-leakage interrupter 10 is demonstrated, and the primary conductor 11R, 11S, 11T is connected to the earth-leakage interrupter 10 as an AC circuit through which each three-phase energization current flows To do.

  The zero-phase current transformer 12 includes a core 12a made of an annular magnetic material that penetrates a plurality (three) of primary conductors 11R, 11S, and 11T that form an AC circuit through which each of the three-phase currents flows. (Annular iron core) and a toroidal leakage detection coil wound around the core 12a. The plurality of primary conductors 11R, 11S, and 11T are provided in a state that is maintained at a substantially constant distance so that the distance between the primary conductors does not change in the region before and after the through-hole of the zero-phase current transformer 12. It is preferable. In addition, the core 12a of the zero-phase current transformer 12 is preferably formed in a track shape having a long side and a short side in order to ensure the downsizing of the leakage breaker 10 and the improvement of the assemblability. Here, the shape is a track shape, but it is an annular shape having a long side and a short side, such as an oval shape or an elliptical shape, and includes shapes having different dimensions in two orthogonal directions. Further, the leakage detection coil wound around the core 12a is shown in a simplified manner. The zero-phase current transformer 12 outputs an output voltage that is an induced voltage detected at both ends of the leakage detection coil when each energization current flows through the primary conductors 11R, 11S, and 11T. 13 is output.

  The signal processing circuit 13 is composed of an electronic circuit having a predetermined function, and receives the output voltage output from the zero-phase current transformer 12. Further, the signal processing circuit 13 amplifies the input output voltage with a predetermined amplification factor, performs a filtering process, and outputs an analog output voltage signal of the processed output voltage to the A / D conversion circuit 14. .

  The A / D conversion circuit 14 is composed of an electronic circuit having a predetermined function, and receives an analog output voltage signal output from the signal processing circuit 13. The A / D conversion circuit 14 converts the input analog output voltage signal into a digital output voltage value based on a predetermined sampling period. Here, the predetermined sampling period is, for example, 1 [millisecond]. The A / D conversion circuit 14 outputs the converted digital output voltage value to the leakage determination unit 18.

  The leakage determination unit 18 is configured by an electronic circuit having a predetermined function or an IC (Integrated Circuit) on which a CPU (Central Processing Unit) is mounted. The leakage current determination unit 15, the balanced current determination unit 16, and the calculation unit 17. The value of the digital output voltage output by the A / D conversion circuit 14 is input to the leakage current determination unit 15 and the balanced current determination unit 16, respectively.

  The leakage current determination unit 15 inputs the digital output voltage output by the A / D conversion circuit 14 and continuously integrates the value of the input digital output voltage for a predetermined detection unit time. In addition, the leakage current determination unit 15 supplies the leakage current to the primary conductors 11R, 11S, and 11T at the end of the detection unit time according to the sum of the digital output voltages accumulated during the detection unit time. It is determined whether or not. Here, the predetermined detection unit time is a time corresponding to one cycle with respect to the power supply frequency of the AC power supply connected to the primary conductors 11R, 11S, and 11T, and is specified in advance in the operation of the leakage current determination unit 15. It is preferable. For example, the predetermined detection unit time is 20 [milliseconds] when the power supply frequency of the AC power supply is 50 [Hz]. Note that time information is always output to the leakage current determination unit 15 from an internal timer (not shown) included in the leakage determination unit 18, and so on.

  Specifically, the leakage current determination unit 15 compares the total value of the digital output voltage in the detection unit time described above with a predetermined leakage current determination threshold value H0, and the total value of the digital output voltage in the detection unit time is determined. When the leakage current determination threshold value H0 is exceeded, it is determined that the leakage current is flowing through the primary conductors 11R, 11S, and 11T. In addition, the leakage current determination part 15 calculates the average value or effective value of the said digital output voltage as a value of the sum total of the digital output voltage in the said detection unit time. The leakage current determination threshold value H0 is a threshold value for determining whether or not a leakage current is flowing through each primary conductor 11R, 11S, 11T, and is specified in advance in the operation of the leakage current determination unit 15. Is preferred. The leakage current determination unit 15 outputs a leakage current determination signal corresponding to the determination result to the calculation unit 17.

  Here, as shown in FIG. 5A to be described later, as the output voltage of the zero-phase current transformer 12 (dotted line in the figure), a waveform substantially equivalent to a sine wave (solid line in the figure) with very little distortion. Is output, the core 12a of the zero-phase current transformer 12 is not magnetically saturated, and the current flowing in the forward direction of the primary conductors 11R, 11S, and 11T and the current flowing in the return direction are Differences occur between them. When this difference exceeds the above-described leakage current determination threshold value H0, the leakage current determination unit 15 determines that a leakage current has occurred in any of the primary conductors 11R, 11S, and 11T.

  The balanced current determination unit 16 inputs the digital output voltage output from the A / D conversion circuit 14 and continues the value of the input digital output voltage for the same detection unit time as the leakage current determination unit 15. And accumulate. Further, the balanced current determination unit 16 detects the peak value of the input digital output voltage during the detection unit time. The balanced current determination unit 16 also determines the sum of the digital output voltages accumulated during the detection unit time and the peak of the digital output voltage detected during the detection unit time at the end of the detection unit time. Depending on the value, it is determined whether or not an equilibrium current is flowing through the primary conductors 11R, 11S, and 11T. Here, the predetermined detection unit time is similarly a time corresponding to one cycle with respect to the power supply frequency of the AC power supply connected to the primary conductors 11R, 11S, and 11T, and is specified in advance in the operation of the balanced current determination unit 16. It is preferable that Further, the time width of the predetermined detection unit time is the same in the following embodiments. It should be noted that time information is constantly output to the balanced current determination unit 16 from an internal timer (not shown) included in the leakage determination unit 18, and so on.

  Specifically, the balanced current determination unit 16 calculates an average value or an effective value of the digital output voltage based on the value of the sum of the digital output voltages in the detection unit time described above, and the peak of the detected digital output voltage. A value obtained by dividing the value by the calculated average value or effective value is compared with a predetermined equilibrium current determination threshold value H1. When the value obtained by dividing the peak value of the digital output voltage in the detection unit time by the average value or the effective value exceeds the equilibrium current determination threshold value H1, the balanced current determination unit 16 applies the primary conductors 11R, 11S, and 11T to the primary conductors 11R, 11S, and 11T. It is determined that the equilibrium current is energized. The equilibrium current determination threshold value H1 is a threshold value for determining whether or not an equilibrium current is flowing through each primary conductor 11R, 11S, 11T, and is defined in advance in the operation of the equilibrium current determination unit 16. Is preferred. Note that, when the average value of the digital output voltage is calculated, the balanced current determination unit 16 preferably performs the calculation by inverting the minus component of the digital output voltage to the plus component. The balanced current determination unit 16 outputs a balanced current determination signal corresponding to the determination result to the calculation unit 17.

  Here, as shown in FIG. 6 and FIG. 7 described later, the output voltage of the zero-phase current transformer 12 (solid line in the figure) is less distorted than a sine wave (dotted line in the figure) with a very small distortion. When a very large waveform is output, the core 12a of the zero-phase current transformer 12 is in a magnetically saturated state, so the current flowing in the forward direction of the primary conductors 11R, 11S, and 11T and the return direction are determined. There is almost no difference between the flowing current. When the value obtained by dividing the peak value of the digital output voltage in the detection unit time by the average value or the effective value exceeds the above-described balanced current determination threshold value H1, the balanced current determination unit 16 applies the primary conductors 11R, 11S, and 11T to the primary conductors 11R, 11S, and 11T. Determines that an equilibrium current is generated.

  The calculation unit 17 inputs the leakage current determination signal output from the leakage current determination unit 15 and the balance current determination signal output from the balance current determination unit 16, and performs a predetermined calculation based on the input signals. I do. Specifically, the calculation unit 17 calculates a logical product of the leakage current determination signal output from the leakage current determination unit 15 and the inverted output signal of the balanced current determination signal output from the balanced current determination unit 16. The calculation unit 17 outputs a leakage determination signal corresponding to the calculation result of the logical product to the switching control unit 19.

  The details of the leakage determination signal, which is the calculation result of the calculation unit 17, will be described with reference to FIG. FIG. 2 is an explanatory diagram showing the relationship among the leakage current determination signal, the equilibrium current determination signal, the leakage determination signal, and the open / close state of the circuit contact. As described above, the leakage determination signal corresponding to the calculation result of the calculation unit 17 in FIG. 2 is calculated by the logical product of the leakage current determination signal and the inverted output signal of the balanced current determination signal.

  Specifically, the leakage determination unit 18 determines that the leakage current is generated by the leakage current determination unit 15 in response to the calculation result of the calculation unit 17, and the equilibrium current determination unit 16 determines that the equilibrium current is Only when it is determined that no current is supplied (corresponding to the output C1), it is determined that a leakage current is generated in the primary conductors 11R, 11S, and 11T. Therefore, the leakage determination unit 18 corresponds to the calculation result of the calculation unit 17, and when the leakage current determination unit 15 determines that no leakage current has occurred (corresponding to the outputs A1 and B1), the primary conductor 11R. , 11S, 11T are determined to have no leakage current. In addition, when the leakage current is generated but the balanced current is flowing (corresponding to the output D1), the leakage determination unit 18 determines that the leakage current is not generated in the primary conductors 11R, 11S, and 11T. In response to the occurrence of the leakage current, the switching control unit 19 is controlled not to output a signal for opening an electric circuit contact described later. Thereby, the earth leakage determination part 18 can aim at reduction of the malfunctioning of the earth leakage breaker 10 whole. The leakage determination unit 18 outputs a leakage determination signal corresponding to the determination result to the open / close control unit 19.

  The open / close control unit 19 is configured by an electronic circuit having a predetermined function, inputs the leakage determination signal output by the leakage determination unit 18, and the AC contacts 20R of the AC circuit according to the input leakage determination signal. Control is performed so that 20S and 20T are turned on (on) or released (off). Specifically, as shown in the open / close state of the circuit contact in FIG. 2, the switching control unit 19 is primary only when the leakage determination signal that is the calculation result of the calculation unit 17 is “1” (corresponding to the output C1). Assuming that a leakage current is generated in any of the conductors 11R, 11S, and 11T, control is performed to turn off the electric circuit contacts 20R, 20S, and 20T. The open / close control unit 19 controls the circuit contacts 20R, 20S, and 20T to be turned on when the leakage determination signal that is the calculation result of the calculation unit 17 is “0”.

2. Description of an Example of Operation of the Earth Leakage Determination Unit 18 of the Earth Leakage Breaker 10 of the First Embodiment FIG. 3 is an explanatory diagram illustrating an example of operation of the earth leakage interrupter 10 of the first embodiment. FIG. 2A is an explanatory diagram in the case where a leakage current is generated in any of the primary conductors 11R, 11S, and 11T and no balanced current is flowing in the primary conductors 11R, 11S, and 11T. This corresponds to the pattern of the output C1. FIG. 2B is an explanatory diagram when a leakage current is generated in the primary conductors 11R, 11S, and 11T and an equilibrium current is flowing in the primary conductors 11R, 11S, and 11T, and the output D1 in FIG. It corresponds to the pattern of.

  First, FIG. 3A will be described. Prior to time t1 in FIG. 3A, no leakage current is generated in any of the primary conductors 11R, 11S, and 11T, and the leakage current determination unit 15 and the equilibrium current determination unit at times t1 to t2. It is assumed that a digital output voltage value corresponding to an analog output voltage signal of the zero-phase current transformer 12 as shown in FIG.

  In FIG. 3A, at time t1 to t2 and time t2 to t3, according to the output voltage of the zero-phase current transformer 12, is any leakage current generated in any of the primary conductors 11R, 11S, and 11T? And a detection unit time for determining whether or not a balanced current is flowing through the primary conductors 11R, 11S, and 11T. As described above, this detection unit time is preferably a time corresponding to one cycle with respect to the power supply frequency of the AC power supply connected to the primary conductors 11R, 11S, and 11T.

  In FIG. 3A, the leakage current determination unit 15 continuously integrates the value of the digital output voltage converted by the A / D conversion circuit 14 during the detection unit time from time t1 to time t2. The total value of the integrated digital output voltage is preferably an average value or an effective value of the digital output voltage at times t1 to t2, and is shown as a leakage current determination unit calculation result in FIG. Yes.

  The leakage current determination unit 15 determines whether the total value of the digital output voltages during the detection unit time t1 to t2 exceeds the predetermined leakage current determination threshold value H0 described above at the time t2 when the detection unit time ends. Determine whether or not. As shown in the calculation result of the leakage current determination unit in FIG. 3A, since the sum of the digital output voltages during the detection unit time t1 to t2 exceeds a predetermined leakage current determination threshold value H0, the leakage current determination The unit 15 determines that a leakage current has occurred in any of the primary conductors 11R, 11S, and 11T in the detection unit times t1 to t2. The leakage current determination unit 15 outputs the leakage current determination signal corresponding to the determination result to “1” to the calculation unit 17 (see FIG. 2).

  In FIG. 3A, the balanced current determination unit 16 continuously integrates the value of the digital output voltage converted by the A / D conversion circuit 14 during the detection unit time from time t1 to time t2. The total sum of the digital output voltages is preferably an average value or an effective value of the digital output voltage at times t1 to t2.

  The balanced current determination unit 16 determines the average value or effective value of the digital output voltage based on the sum of the digital output voltages during the detection unit time t1 to t2 at the time t2 when the detection unit time ends. And a value obtained by dividing the peak value of the digital output voltage detected during the detection unit time t1 to t2 by the calculated average value or effective value is compared with a predetermined equilibrium current determination threshold value H1. . As shown in the calculation result of the balanced current determination unit 16 in FIG. 3A, the value obtained by dividing the peak value of the digital output voltage by the calculated average value or effective value is less than the balanced current determination threshold value. For this reason, the balanced current determination unit 16 determines that no balanced current flows through the primary conductors 11R, 11S, and 11T in the detection unit times t1 to t2. The balanced current determination unit 16 outputs the balanced current determination signal corresponding to the determination result as “0” to the calculation unit 17 (see FIG. 2).

  The arithmetic unit 17 calculates the logic between the leakage current determination signal “1” and the inverted output “1” of the balance current determination signal based on the input “1” of the leakage current determination signal and the input “0” of the balance current determination signal. The product is calculated, and a leakage determination signal “1” corresponding to the calculation result is output to the switching control unit 19 (see FIG. 2).

  The switching control unit 19 controls the circuit contacts 20R, 20S, and 20T to be turned off by assuming that a leakage current is generated in any of the primary conductors 11R, 11S, and 11T by the input of the leakage determination signal “1”. . Before time t2 in FIG. 3A, no leakage occurred in any of the primary conductors 11R, 11S, and 11T, and thus the leakage determination signal of the leakage determination unit 18 was “0”. However, as described above, since it is determined that leakage has occurred in any of the primary conductors 11R, 11S, and 11T at time t2, the switching controller 19 causes the circuit contacts 20R, 20S, and AC of the AC circuit after time t2. By controlling to turn off 20T, “1” is continued as the leakage determination signal. That is, the earth leakage interrupter 10 interrupts the supply of AC power from the AC power source.

  Next, FIG. 3B will be described. In addition, before the time t1 of FIG.3 (b), the earth leakage current has not generate | occur | produced in any of the primary conductors 11R, 11S, and 11T, and the earth leakage current determination part 15 and the equilibrium current determination part in the time t1-t2. It is assumed that a digital output voltage value corresponding to an analog output voltage signal of the zero-phase current transformer 12 as shown in FIG.

  In FIG. 3 (b), at time t4 to t5 and time t5 to t6, according to the output voltage of the zero-phase current transformer 12, is any leakage current generated in any of the primary conductors 11R, 11S, and 11T? And a detection unit time for determining whether or not a balanced current is flowing through the primary conductors 11R, 11S, and 11T. As described above, this detection unit time is preferably a time corresponding to one cycle with respect to the power supply frequency of the AC power supply connected to the primary conductors 11R, 11S, and 11T.

  In FIG. 3B, the leakage current determination unit 15 continuously integrates the value of the digital output voltage converted by the A / D conversion circuit 14 during the detection unit time from time t4 to t5. The total sum of the digital output voltages is preferably an average value or an effective value of the digital output voltages at times t4 to t5, and is shown as the leakage current determination unit calculation result in FIG. Yes.

  Whether or not the value of the sum of the digital output voltages during the detection unit time t4 to t5 exceeds the predetermined leakage current determination threshold value H0 described above at the time t5 when the detection unit time ends. Determine whether or not. As shown in the calculation result of the leakage current determination unit 15 in FIG. 3B, the sum of the digital output voltages during the detection unit time t4 to t5 exceeds the predetermined leakage current determination threshold value H0. The current determination unit 15 determines that a leakage current has occurred in any of the primary conductors 11R, 11S, and 11T during the detection unit times t4 to t5. The leakage current determination unit 15 outputs the leakage current determination signal corresponding to the determination result to “1” to the calculation unit 17 (see FIG. 2).

  In FIG. 3B, the balanced current determination unit 16 continuously integrates the value of the digital output voltage converted by the A / D conversion circuit 14 during the detection unit time from time t4 to time t5. The total sum of the digital output voltages is preferably an average value or an effective value of the digital output voltage at times t4 to t5.

  The balanced current determination unit 16 determines the average value or effective value of the digital output voltage based on the sum of the digital output voltages during the detection unit time t4 to t5 at the time t5 when the detection unit time ends. And a value obtained by dividing the peak value of the digital output voltage detected during the detection unit time t4 to t5 by the calculated average value or effective value is compared with a predetermined equilibrium current determination threshold value H1. . As shown in the calculation result of the balanced current determination unit 16 in FIG. 3B, the value obtained by dividing the peak value of the digital output voltage by the calculated average value or effective value exceeds the balanced current determination threshold value. For this reason, the balanced current determination unit 16 determines that the balanced current is flowing in the primary conductors 11R, 11S, and 11T during the detection unit times t4 to t5. The balanced current determination unit 16 outputs the balanced current determination signal corresponding to the determination result as “1” to the calculation unit 17 (see FIG. 2).

  The arithmetic unit 17 calculates the logic between the leakage current determination signal “1” and the inverted output “0” of the balanced current determination signal based on the input “1” of the leakage current determination signal and the input “1” of the equilibrium current determination signal. The product is calculated, and a leakage determination signal “0” corresponding to the calculation result is output to the switching control unit 19 (see FIG. 2).

  The open / close control unit 19 controls to turn on the electric circuit contacts 20R, 20S, and 20T on the assumption that no leakage current is generated in any of the primary conductors 11R, 11S, and 11T by the input of the leakage determination signal “0”. . Before time t5 in FIG. 3B, no leakage occurred in any of the primary conductors 11R, 11S, and 11T, and thus the leakage determination signal of the leakage determination unit 18 was “0”. Furthermore, since it is determined that no leakage has occurred in any of the primary conductors 11R, 11S, and 11T at time t5, the switching control unit 19 turns on the circuit contacts 20R, 20S, and 20T of the AC circuit from time t5 to t6. By controlling in this way, the leakage determination signal is continued in the state of “0”. That is, the earth leakage breaker 10 continues to supply AC power from the AC power source. However, since the supply of AC power from the AC power source is continued, the balanced current determination unit 16 similarly similarly at times t5 to t6, which is the next detection unit time after times t4 to t5. The total sum of the digital output voltages accumulated in is reset, and the presence / absence of energization of the balanced current is determined as described above.

  In FIG. 3, the case of the output C1 and the output D1 in FIG. 2 has been described. However, in both cases of the output A1 and the output B1 in FIG. Control to turn on 20S and 20T. Specifically, in the case of the output A1 and the output B1 in the figure, since the leakage current determination signal of the leakage current determination unit 15 is “0”, the calculation unit 17 is connected to the primary conductors 11R, 11S, and 11T. A leakage determination signal “0” indicating that a leakage current has not occurred is output to the switching control unit 19. Therefore, the open / close control unit 19 turns on the circuit contacts 20R, 20S, and 20T on the assumption that no leakage current is generated in any of the primary conductors 11R, 11S, and 11T due to the input of the leakage determination signal “0”. Control.

  FIG. 4 is an explanatory diagram showing a calculation result when the balanced current is energized and a calculation result when a leakage current is generated, respectively. FIG. 5A is an explanatory diagram when a peak value / average value, which is a ratio between a peak value and an average value, is calculated as the calculation result. FIG. 4B is an explanatory diagram when a peak value / effective value that is a ratio of a peak value to an effective value is calculated as the calculation result.

  As shown in FIG. 4A, in the calculation result when the balanced current is energized, the value of the ratio between the peak value and the average value of the digital output voltage exceeds the above-described predetermined balanced current determination threshold value H1. It has been shown. Further, as shown in FIG. 4B, in the calculation result when the balanced current is energized, the ratio value between the peak value and the effective value of the digital output voltage exceeds the above-described predetermined balanced current determination threshold value H1. It is shown that.

  Further, as shown in FIG. 4A, in the calculation result when the leakage current occurs, the value of the ratio between the peak value and the average value of the digital output voltage is less than the predetermined equilibrium current determination threshold value H1 described above. It has been shown. Further, as shown in FIG. 4B, in the calculation result when the leakage current is generated, the ratio value between the peak value and the effective value of the digital output voltage is less than the predetermined equilibrium current determination threshold value H1 described above. It has been shown.

  Further, comparing FIGS. 4A and 4B, the effective value of the digital output voltage is calculated by squaring and integrating the value of the digital output voltage in the calculation process. When determining the presence / absence of energization of the equilibrium current in the primary conductors 11R, 11S, and 11T, the peak shown in FIG. 4A is calculated rather than calculating the ratio value between the peak value and the effective value shown in FIG. It can be seen that the calculation accuracy of the ratio of the value and the average value improves the determination accuracy of the balanced current.

  FIG. 5 is an explanatory diagram showing a time change between the leakage current and the output voltage of the zero-phase current transformer 12. FIG. 5A is an explanatory diagram showing a change over time when the leakage current is 2 [A]. FIG. 4B is an explanatory diagram showing a change over time when the leakage current is 20 [A]. FIG. 4C is an explanatory diagram showing a change over time when the leakage current is 50 [A]. In FIG. 5A, it can be said that the output voltage of the zero-phase current transformer 12 has a shape close to a sine wave with relatively small distortion. 5B and 5C, the output voltage of the zero-phase current transformer 12 is much larger than that in FIG. 5A, and the waveform of the output voltage is also very distorted. In such a case, excessive leakage in the second embodiment to be described later occurs in the primary conductors 11R, 11S, and 11T.

  FIG. 6 is an explanatory diagram showing a time change between the balanced current and the output voltage of the zero-phase current transformer 12. FIG. 4A is an explanatory diagram showing a change with time when the equilibrium current is 100 [A]. FIG. 4B is an explanatory diagram showing a change over time when the equilibrium current is 200 [A]. FIG. 6C is an explanatory diagram showing a change over time when the equilibrium current is 350 [A]. FIG. 7 is an explanatory diagram showing a time change between the balanced current and the output voltage of the zero-phase current transformer 12. FIG. 6A is an explanatory diagram showing a change over time when the equilibrium current is 600 [A]. FIG. 4B is an explanatory diagram showing a change over time when the equilibrium current is 1100 [A]. FIG. 4C is an explanatory diagram showing a change over time when the equilibrium current is 1650 [A]. In FIGS. 6 and 7, the waveform of the output voltage of the zero-phase current transformer 12 is relatively greatly distorted when compared with the waveforms of the respective energized currents (balanced currents) shown in the corresponding figures. Big. In such a case, a balanced current is applied to the primary conductors 11R, 11S, and 11T.

  As described above, according to the leakage breaker 10 of the first embodiment, it is possible to reduce the arrangement amount of the magnetic shield with respect to the core 12a of the zero-phase current transformer 12 having a circular shape or a non-circular shape. As a result, the number of parts of the earth leakage breaker 10 can be reduced, and an increase in size of the earth leakage breaker 10 can be avoided. In addition, according to the leakage breaker 10, the manufacturing cost of the leakage breaker 10 can be reduced.

  Furthermore, the leakage breaker 10 determines whether or not a leakage current is generated and whether or not a balanced current is energized in a detection unit time corresponding to one cycle with respect to the power frequency of the AC power supply. For this reason, it is possible to determine whether or not the leakage current is generated and whether or not the balanced current is applied in a very short time of at least one cycle with respect to the power supply frequency of the AC power supply.

  Further, in order to determine whether or not the leakage current is generated and whether or not the balanced current is applied, the output voltage of the zero-phase current transformer 12 is set by the single signal processing circuit 13 and the A / D conversion circuit 14. The current is input to the leakage current determination unit 15 and the equilibrium current determination unit 16, respectively. This eliminates the need for a complicated circuit configuration such as providing the signal processing circuit 13 and the A / D conversion circuit 14 for each of the primary conductors 11R, 11S, and 11T when determining whether or not the leakage current is generated and whether or not the balanced current is applied. Therefore, the leakage breaker 10 that can be determined with high accuracy in a very short time can be realized at low cost. In particular, when the value obtained by dividing the peak value of the digital output voltage during the detection unit time by the average value of the digital output voltage is used, when the value divided by the effective value of the digital output voltage is used. In comparison, the presence / absence of energization of the balanced current can be determined with higher accuracy.

(Second Embodiment)
3. FIG. 8 is a circuit block diagram showing the circuit configuration of the leakage breaker 10 of the second embodiment. In FIG. 8, the same parts as those in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted, and different parts are mainly described here.

  As shown in FIG. 8, the leakage breaker 10a includes a zero-phase current transformer 12, a signal processing circuit 13, 22 and an A / D conversion circuit 14, 23 that penetrate the primary conductors 11R, 11S, 11T to the inside. The electric leakage determination unit 18a, the open / close control unit 19a, current sensors 21R, 21S, and 21T, and a zero cross detection unit 24 are provided. Also in the second embodiment, it is assumed that a plurality of primary conductors 11R, 11S, and 11T are connected to the earth leakage breaker 10a as an AC circuit through which each of the three-phase currents flows.

  Each current sensor 21R, 21S, and 21T is provided corresponding to each primary conductor 11R, 11S, and 11T, always measures the energization current of the corresponding primary conductor 11R, 11S, and 11T, and each measured energization is measured. The current is output to the signal processing circuit 22.

  The signal processing circuit 22 inputs each energization current output from each current sensor 21R, 21S, 21T. Further, the signal processing circuit 22 amplifies each input energized current with a predetermined amplification factor, performs a filter process, and sends the processed analog output current signal of each energized current to the A / D conversion circuit 23. Output.

  The A / D conversion circuit 23 receives the analog output current signal output by the signal processing circuit 22. The A / D conversion circuit 23 converts the input analog output current signal into a digital output current value based on a predetermined sampling period. Here, the predetermined sampling period is, for example, 1 [millisecond]. The A / D conversion circuit 23 outputs the converted digital output current value to the zero-cross detection unit 24.

  The zero-cross detection unit 24 is configured by an electronic circuit having a predetermined function or an IC on which a CPU is mounted, and receives the value of the digital output current output from the A / D conversion circuit 23. Further, the zero-cross detection unit 24 detects a zero point in time of the input digital output current, and outputs a zero-cross detection signal indicating the detection to the balanced current determination unit 16.

  The leakage determination unit 18a is configured by an electronic circuit having a predetermined function or an IC mounted with a CPU, and the like. The leakage current determination unit 15, the equilibrium current determination unit 16, the overleakage current determination unit 25, and the calculation unit 17a. With. The zero cross detection signal output by the zero cross detection unit 24 is output to the balanced current determination unit 16.

  The balanced current determination unit 16 a receives the digital output voltage output from the A / D conversion circuit 14 and the zero cross detection signal output from the zero cross detection unit 24. The balanced current determination unit 16a detects the peak value of the input digital output voltage during a predetermined detection unit time starting from the time when the zero-cross detection signal is input, and during the detection unit time. It is determined whether an equilibrium current is flowing through the primary conductors 11R, 11S, and 11T according to the detected peak value of the digital output voltage. In the second embodiment, the detection unit time of the leakage current determination unit 15 and the overleakage current determination unit 25 is the same time width as the detection unit time of the equilibrium current determination unit 16a, and the leakage current determination unit 15 and The starting point of the detection unit time of overleakage current determination unit 25 is preferably the same as the detection unit time of balanced current determination unit 16a.

  A specific operation example of the balanced current determination unit 16a will be described with reference to FIG. FIG. 9 is an explanatory diagram for explaining the determination of the presence or absence of the application of the balanced current in the balanced current determination unit in the second embodiment, and the graph of the time variation of the balanced current and the output voltage of the zero-phase current transformer 12 is This is the same as that shown in FIG.

  As shown in FIG. 9, the balanced current determination unit 16a outputs the A / D conversion circuit 14 during the detection unit time (time t7 to t8) starting from the input time (time t7) of the above-described zero cross detection signal. The peak of the digital output voltage between the time when the value of the digital output voltage thus obtained exceeds the absolute value of the predetermined equilibrium current determination thresholds H2 and H3 and the time when the value of the digital output voltage becomes less than the absolute value of the equilibrium current determination thresholds H2 and H3 The detection time (time t7 + tr2, time t7 + tr2 + tr3) of the value (B, C) is detected. Here, as shown in FIG. 9, the detection time t7 + tr2 and the time t7 + t2 + t3 are both times before the time t8, and are included between the target detection unit times t7 to t8. In addition, time information is always output to the balanced current determination unit 16a from an internal timer (not shown) included in the leakage determination unit 18a, as in the first embodiment. The predetermined equilibrium current determination threshold values H2 and H3 are threshold values for determining whether or not an equilibrium current is flowing through the primary conductors 11R, 11S, and 11T, and are defined in advance in the operation of the equilibrium current determination unit 16a. It is preferable that

  The equilibrium current determination unit 16a determines whether or not the peak value of the digital output voltage in the detection unit time satisfies a predetermined equilibrium current determination condition at the end of the detection unit time (time t8). Here, the equilibrium current determination condition is that there are two or more peak values of the digital output voltage detected during the predetermined detection unit time, or two or more peak values of the digital output voltage. In addition, the polarities of the peak values are all the same polarity. The balanced current determination unit 16a determines that the balanced current is flowing in the primary conductors 11R, 11S, and 11T when the peak value detected in the detection unit time satisfies the balanced current determination condition.

  In FIG. 9, since there are two or more peak values of the digital output voltage detected during the detection unit time t7 to t8, the balanced current determination unit 16a determines that the balanced current is detected during the detection unit time t7 to t8. It is determined that the determination condition is satisfied. Similarly, since there are two or more peak values of the digital output voltage detected during the detection unit time t8 to t9, the balanced current determination unit 16a satisfies the equilibrium current determination condition during the detection unit time t8 to t9. It is determined that The balanced current determination unit 16a outputs a balanced current determination signal corresponding to the determination result to the calculation unit 17.

  Here, as shown in FIG. 6 and FIG. 7, the distortion of the output voltage of the zero-phase current transformer 12 (solid line in FIG. 6) is much less than that of a sine wave (dotted line in FIG. When a large waveform is output, since the core 12a of the zero-phase current transformer 12 is in a magnetic saturation state, the current flowing in the forward direction of the primary conductors 11R, 11S, and 11T and the current flowing in the return direction There is almost no difference between The balanced current determination unit 16a determines that any balanced current is generated in the primary conductors 11R, 11S, and 11T when the peak value of the digital output voltage in the detection unit time satisfies the balanced current determination signal described above. To do.

  The over-leakage current determination unit 25 inputs the digital output voltage output from the A / D conversion circuit 14 and inputs the input during the same detection unit time as the above-described leakage current determination unit 15 and the balanced current determination unit 16a. Continue to integrate the digital output voltage values. In addition, the overcurrent leakage current determination unit 25 generates an overcurrent leakage current in the primary conductors 11R, 11S, and 11T according to the sum of the digital output voltages accumulated during the detection unit time during the detection unit time. It is determined whether or not power is being supplied. In the following explanation, when an excessive leakage occurs in the AC circuit, an excessive current generated based on the difference between the current flowing in the forward direction and the current flowing in the return direction of the primary conductor constituting the AC circuit. Is referred to as overleakage current. Here, the predetermined detection unit time is a time corresponding to one cycle with respect to the power supply frequency of the AC power supply connected to the primary conductors 11R, 11S, and 11T, and is specified in advance in the operation of the overcurrent leakage current determination unit 25. Preferably it is.

  Specifically, overleakage current determination unit 25 compares the sum of the digital output voltages output by A / D conversion circuit 14 in the detection unit time described above with a predetermined overleakage current determination threshold H4, and Even when the total value of the digital output voltages exceeds the leakage current determination threshold value H4 and before the end of the detection unit time, it is determined that an excessive leakage current is generated in the primary conductors 11R, 11S, and 11T. . In addition, the passage leakage current determination unit 25 calculates an average value or an effective value of the digital output voltage as a value of the sum of the digital output voltages in the detection unit time.

  Therefore, the overleakage current determination unit 25 determines that overleakage current is generated in the primary conductors 11R, 11S, and 11T, for example, at an intermediate time before the end of the detection unit time. As will be described in detail later, when it is determined that an overcurrent leakage current has occurred, the calculation unit 17a performs the primary conductor 11R regardless of the determination results of the leakage current determination unit 15 and the equilibrium current determination unit 16a. , 11S, 11T, a leakage determination signal indicating that an overcurrent leakage current has occurred is quickly output to the switching control unit 19a. As a result, the leakage breaker 10a is more sensitive to the excess leakage current than the leakage breaker 10 shown in the first embodiment when an excessive leakage current occurs in any of the primary conductors 11R, 11S, and 11T. It is possible to determine at high speed that a leakage has occurred in the primary conductors 11R, 11S, and 11T.

  The overleakage current determination threshold value H4 is a threshold value for determining whether or not the overleakage current is flowing through the primary conductors 11R, 11S, and 11T, and is defined in advance in the operation of the overleakage current determination unit 25. It is preferable. Overleakage current determination unit 25 outputs an overleakage current determination signal corresponding to the determination result to calculation unit 17a.

  Here, as shown in FIGS. 5B and 5C, when an output voltage having an extremely large waveform is output as the output voltage of the zero-phase current transformer 12 (dotted line in FIG. 5), the primary voltage There is a very large difference between the current flowing in the forward direction of each of the conductors 11R, 11S, and 11T and the current flowing in the return direction. When this difference exceeds the above-described over-leakage current determination threshold H4, the over-leakage current determination unit 25 generates an over-leakage current (solid line in the figure) in any of the primary conductors 11R, 11S, and 11T. It is determined that

  The calculation unit 17a receives the leakage current determination signal output from the leakage current determination unit 15, the equilibrium current determination signal output from the equilibrium current determination unit 16a, and the overleakage current determination signal output from the overleakage current determination unit 25. In addition to the input, a predetermined calculation is performed based on each input signal. Specifically, the calculation unit 17a calculates a logical product of the leakage current determination signal output by the leakage current determination unit 15 and the inverted output signal of the balanced current determination signal output by the balanced current determination unit 16a. Furthermore, the calculating part 17a calculates the logical sum of the signal corresponding to the calculated result and the overleakage current determination signal output by the overleakage current determination part 25. The calculation unit 17 a outputs a leakage determination signal corresponding to the calculation result of the logical sum to the switching control unit 19.

  The details of the leakage determination signal, which is the calculation result of the calculation unit 17a, will be described with reference to FIG. FIG. 10 is an explanatory diagram showing the relationship between the leakage current determination signal, the equilibrium current determination signal, the overleakage current determination signal, the leakage determination signal, and the open / close state of the circuit contact. As described above, the calculation result of the calculation unit 17a in FIG. 10 is the logical product of the leakage current determination signal and the inverted output signal of the balanced current determination signal, and the logical sum of the logical product and the overleakage current determination signal. .

  Specifically, the leakage determination unit 18a determines that the leakage current is generated by the leakage current determination unit 15 and the balanced current corresponding to the calculation result of the calculation unit 17a, as in the first embodiment. When the determination unit 16a determines that no equilibrium current is flowing, it is determined that a leakage current is generated in the primary conductors 11R, 11S, and 11T. Furthermore, the leakage determination unit 18a corresponds to the calculation result of the calculation unit 17a or the determination result of the overleakage current determination unit 25, and when the overleakage current determination unit 25 determines that an overleakage current has occurred. Determines that an excessive leakage current is generated in the primary conductors 11R, 11S, and 11T regardless of the determination results of the leakage current determination unit 15 and the equilibrium current determination unit 16a. Therefore, when neither the leakage current nor the excessive leakage current is generated, or when the leakage current is generated but the balanced current is flowing, the leakage determination unit 18a determines the primary conductors 11R, 11S, and 11T. It is determined that there is no leakage current and no over-leakage current, and control is performed so as not to cause the switching control unit 19a to output a signal to open an electric circuit contact described later according to the occurrence of the leakage current or over-leakage current. . Thereby, the earth leakage determination part 18a can aim at reduction of the malfunctioning of the earth leakage breaker 10a whole. The leakage determination unit 18a outputs a leakage determination signal corresponding to the determination result to the open / close control unit 19a.

  The open / close control unit 19a is configured by an electronic circuit having a predetermined function, and inputs the leakage determination signal output by the leakage determination unit 18a, and the AC contact 20R of the AC circuit according to the input leakage determination signal. Control is performed so that 20S and 20T are turned on (on) or released (off). Specifically, the open / close control unit 19a, as shown in the open / close state of the circuit contact in FIG. 10, is when the leakage determination signal as the calculation result of the calculation unit 17a is “1” (outputs C2, E2, F2). , G2, and H2), the circuit contacts 20R, 20S, and 20T are controlled to be turned off assuming that the leakage current or overcurrent is generated in any of the primary conductors 11R, 11S, and 11T. The switching controller 19 controls the circuit contacts 20R, 20S, and 20T to be turned on when the leakage determination signal that is the calculation result of the calculator 17a is “0” (corresponding to the outputs A2, B2, and D2). To do.

4). FIG. 11 is a flowchart illustrating an operation of the balanced current determination unit 16a of the leakage breaker 10a according to the second embodiment. In the following description of the flowchart, the contents of FIG. 9 will be referred to as appropriate. The description of the operation of the balanced current determination unit 16a shown in FIG. 11 is performed for one detection unit time (time t7 to t8) shown in FIG. 9, and in the subsequent detection unit time (after time t8). The same process is repeated repeatedly.

  The balanced current determination unit 16a is configured to detect the detection unit during a predetermined detection unit time (time t7 to t8) starting from the input time (time t7 in FIG. 9) of the zero cross detection signal output by the zero cross detection unit 24. It is determined whether or not there is a digital output voltage value output by the A / D conversion circuit 14 over time that exceeds the equilibrium current determination threshold H2 or H3 (S11).

  In step S11, when it is determined that there is a value of the digital output voltage exceeding the absolute value of the balanced current determination threshold H2 or H3 (S11, YES), the balanced current determining unit 16a The number of peaks of the digital output voltage exceeding the absolute value of the determination threshold H2 or H3 is counted (S12). Further, the balanced current determination unit 16a determines the polarity of the peak value of the counted digital output voltage (S13).

  In step S11, when it is determined that none of the digital output voltage values exceed the absolute value of the balanced current determination threshold H2 or H3 (S11, NO), or after step S13, the balanced current determination unit 16a determines whether or not the detection unit time that is the target of the operation in step S11 has ended (S14). If it is determined in step S14 that the detection unit time that is the target of the operation in step S11 has not ended (S14, NO), the operation returns to the operation in step S11 and the operation described above is the end of the detection unit time. Repeat until judged.

  When it is determined in step S14 that the detection unit time that is the target of the operation in step S11 has ended (S14, YES), the balanced current determination unit 16a has the peak value of the digital output voltage counted in step S12. It is determined whether or not the above-described equilibrium current determination condition is satisfied (S15). As described above, the equilibrium current determination condition is that there are two or more digital output voltage peak values detected during the predetermined detection unit time described above, or two or more digital output voltage peak values. And the polarities of the peak values are all the same.

  The balanced current determination unit 16a determines that the two peak values counted in step S12 during the detection unit times t7 to t8 satisfy the balanced current determination condition (S15, YES), and sets the primary conductors 11R, 11S, and 11T to the primary conductors 11R, 11S, and 11T. It is determined that the balanced current is energized (S16). When it is determined that the peak value counted in step S12 during the detection unit times t7 to t8 does not satisfy the equilibrium current determination condition (S15, NO), the equilibrium current determination unit 16a includes the primary conductor 11R, It is determined that the balanced current is not supplied to 11S and 11T (S17). The balanced current determination unit 16a outputs a balanced current determination signal corresponding to the determination result to the calculation unit 17, and the operation illustrated in the flowchart of FIG. 11 ends.

  FIG. 12 is an explanatory diagram showing the relationship between the average value of the output voltage of the zero-phase current transformer when the leakage current is generated and when the balanced current is energized. In FIG. 12, when a large leakage current (overleakage current) of 15 [A] or more is generated in any of the primary conductors 11R, 11S, and 11T, the output voltage of the zero-phase current transformer 12 As shown, a very large output is shown. As described above, the earth leakage breaker 10a according to the second embodiment is provided with the over-leakage current determination unit 25, so that when an over-leakage current occurs in any of the primary conductors 11R, 11S, 11T, Prior to the output of the determination results of the interrupting device 15 and the balanced current determination unit 16a, it is possible to determine at a high speed that excessive leakage based on the excessive leakage current has occurred in the primary conductors 11R, 11S, and 11T.

  In FIG. 12, the average value of the output voltage of the zero-phase current transformer 12 when the equilibrium current is energized when a permalloy shield or a silicon steel plate shield is provided around the core 12 a of the zero-phase current transformer 12. It is shown. By providing these shields, the average value of the output voltage of the zero-phase current transformer 12 can be kept low even when, for example, a balanced current of about 400 [A] corresponding to approximately three times the rated current is energized. Reduction of unnecessary output can be realized. Further, for example, even when a balanced current of 1650 [A] corresponding to 11 times the rated current is energized, the average value of the output voltage of the zero-phase current transformer 12 is kept low, thereby reducing unnecessary output. can do.

  As described above, according to the leakage breaker 10a of the second embodiment, the arrangement amount of the magnetic shield with respect to the core 12a of the zero-phase current transformer 12 having a circular shape or a non-circular shape can be reduced. As a result, the number of parts of the earth leakage breaker 10a can be reduced, and the size of the earth leakage breaker 10a can be avoided. Further, according to the leakage breaker 10a, the manufacturing cost of the leakage breaker 10a can be reduced.

  Furthermore, the leakage breaker 10a determines whether or not a leakage current is generated, whether or not a balanced current is applied, and whether or not an excessive leakage current is generated in a detection unit time corresponding to one cycle with respect to the power supply frequency of the AC power supply. In particular, the leakage breaker 10a determines that the primary conductors 11R, 11S, and 11T, regardless of the determination results of the leakage current determination unit 15 and the balanced current determination unit 16a, when it is determined that an excessive leakage current has occurred. An electric leakage determination signal indicating that an excessive electric leakage current has occurred in either one is quickly output to the switching control unit 19a. As a result, the leakage breaker 10a is more sensitive to the excess leakage current than the leakage breaker 10 shown in the first embodiment when an excessive leakage current occurs in any of the primary conductors 11R, 11S, and 11T. It is possible to determine at high speed that a leakage has occurred in the primary conductors 11R, 11S, and 11T.

  Further, when determining whether or not the balanced current is supplied in the leakage breaker 10a, whether or not the balanced current determination condition is satisfied based on the number and polarity of the peak values of the digital output voltage during the detection unit time. Judgment. For this reason, the leakage breaker 10a can determine the presence / absence of energization of the balanced current at a higher speed and with higher accuracy than the leakage breaker 10 of the first embodiment when determining the energization of the balanced current. it can. Further, it is possible to eliminate a complicated circuit configuration such as providing the signal processing circuit 13 and the A / D conversion circuit 14 for each of the primary conductors 11R, 11S, and 11T when determining whether or not the balanced current is applied. In addition, it is possible to realize the leakage breaker 10 that can be determined with high accuracy in a short time at low cost.

  Furthermore, the leakage breaker 10a determines the starting point of the detection unit time for the determination as the time point of zero crossing of the energizing current of the AC circuit when determining the energization of the balanced current. For this reason, the leakage breaker 10a can determine with high accuracy whether or not the balanced current is energized.

(Modification of the second embodiment)
FIG. 13 is a circuit block diagram illustrating an internal configuration of the leakage breaker 10b according to a modification of the second embodiment. The leakage breaker 10b in the modification of the second embodiment is more current-controlled than the leakage breaker 10a of the second embodiment described above, the current sensors 21R, 21S, 21T, the signal processing circuit 22, and the A / D conversion. The circuit 23 and the zero cross detection unit 24 are omitted. Other configurations and operations are the same as those of the ground fault interrupter 10a of the second embodiment, and thus the description regarding the contents is omitted.

  As compared with the leakage breaker 10a of the second embodiment, the leakage breaker 10b according to the modification of the second embodiment is a current sensor 21R, 21S, which is necessary for detecting the zero crossing point of the energization current of the AC circuit. 21T, the signal processing circuit 22, the A / D conversion circuit 23, and the zero cross detection unit 24 are not provided. For this reason, the leakage breaker 10b according to the modification of the second embodiment has the same detection unit as described above at a predetermined timing in the operation of the balanced current determination unit 16a when determining whether or not the balanced current is applied. This determination is performed with respect to time. Therefore, according to the leakage breaker 10b of the modified example of the second embodiment, it is difficult to determine whether or not the balanced current is energized as the leakage breaker 10a of the second embodiment, but the leakage breaker 10b. The number of components that constitutes can be reduced as compared with the leakage breaker 10a of the second embodiment, and can be manufactured more easily and inexpensively.

  Note that the present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  In the second embodiment described above, the balanced current determination unit 16a determines whether or not the balanced current is energized using the input time point of the zero cross detection signal output from the zero cross detection unit 24 as the starting point of the detection unit time. However, the starting point of the detection unit time by the balanced current determination unit 16a is not limited to the input point of the zero cross detection signal. For example, the balanced current determination unit 16a may determine whether or not the balanced current is energized using the timing defined in advance in the operation of the balanced current determination unit 16a as the starting point of the detection unit time regardless of the input of the zero-cross detection signal. . Further, the balanced current determination unit 16a may determine whether or not the balanced current is energized by using a predetermined time before and after the input time of the zero cross detection signal as the detection unit time.

10, 10a, 10b Earth leakage breaker 11R, 11S, 11T Primary conductor 12 Zero phase current transformer 12a Core 13, 22 Signal processing circuit 14, 23 A / D conversion circuit 15 Earth leakage current determination unit 16, 16a Balanced current determination unit 17 , 17a Arithmetic unit 18, 18a Leakage determination unit 19, 19a Opening / closing control unit 20R, 20S, 20T Electrical contact 21R, 21S, 21T Current sensor 24 Zero cross detection unit 25 Overleakage current determination unit

Claims (10)

A zero-phase current transformer including a core made of an annular magnetic material that penetrates a plurality of primary conductors forming an alternating current circuit, and a toroidal coil wound around the core;
In accordance with the output voltage detected by the zero-phase current transformer, a leakage current determination unit that determines whether or not a leakage current is flowing in the AC circuit,
Based on waveform information of the output voltage detected by the zero-phase current transformer, an equilibrium current determination unit that determines whether or not the energization current of the AC circuit is an equilibrium current;
In accordance with each determination result of the leakage current determination unit and the equilibrium current determination unit, a leakage determination unit that determines whether or not a leakage has occurred in the AC circuit,
According to the determination result determined by the leakage determination unit, an open / close control unit that controls opening and closing of the circuit contact provided in the AC circuit,
An earth leakage circuit breaker comprising: The earth leakage breaker according to claim 1,
The waveform information is a ratio between a peak value of the output voltage in a predetermined detection unit time and an effective value of the output voltage in the detection unit time.
The leakage current interrupting device, wherein the balanced current determination unit determines that the energization current of the AC circuit is an equilibrium current when the value of the ratio is larger than a predetermined equilibrium current determination threshold value. The earth leakage breaker according to claim 1,
The waveform information is a ratio between a peak value of the output voltage in a predetermined detection unit time and an average value of the output voltage in the detection unit time.
The leakage current interrupting device, wherein the balanced current determination unit determines that the energization current of the AC circuit is an equilibrium current when the value of the ratio is larger than a predetermined equilibrium current determination threshold value. The electric leakage breaker according to claim 2 or 3,
The predetermined leakage detection unit time is one period with respect to the power supply frequency of the AC power supply. The electric leakage breaker according to any one of claims 2 to 4,
The waveform information is the number of occurrences or polarity of a peak that exceeds a predetermined other equilibrium current determination threshold in the predetermined detection unit time, or the number of occurrences and polarity.
The balanced current determination unit determines whether the current flowing in the AC circuit is an equilibrium current according to the number of occurrences or polarity of a peak exceeding the other equilibrium current determination threshold, or the number of occurrences and polarity. A ground fault circuit interrupter. The electric leakage breaker according to claim 5,
The leakage current interrupting device, wherein the balanced current determining unit determines that the energization current of the AC circuit is a balanced current when the number of occurrences of the peak is at least twice in the predetermined detection unit time. . The electric leakage breaker according to claim 6,
The balanced current determination unit determines that the energization current of the AC circuit is an equilibrium current when the polarity of the peak repeats at least twice continuously in the predetermined detection unit time. apparatus. The electric leakage breaker according to any one of claims 5 to 7,
A zero-cross detector that detects a zero-cross of the energization current of the AC circuit, and
The balanced current determination unit is configured to determine whether or not the energization circuit of the AC circuit is an equilibrium current with a predetermined time including a time point when the zero cross of the energization current of the AC circuit is detected by the zero-cross detection unit as the detection unit time. An earth leakage breaker characterized by determining whether or not. The electric leakage breaker according to any one of claims 1 to 8,
An over-leakage current determination unit that determines whether or not an over-leakage current is flowing in the AC circuit according to the output voltage detected by the zero-phase current transformer;
When the output voltage detected by the zero-phase current transformer exceeds a predetermined over-leakage current determination threshold, the over-leakage current determination unit determines that the energization current of the AC circuit is an over-leakage current,
The earth leakage determination unit prioritizes the determination results of the overcurrent leakage current determination unit over the determination results of the leakage current determination unit and the equilibrium current determination unit, and determines that overleakage has occurred in the AC circuit. An earth leakage breaker characterized by that. The electric leakage breaker according to claim 9, wherein
The electrical leakage breaker characterized in that the open / close control unit opens an electrical circuit contact provided in the alternating current circuit when it is determined by the leakage determination unit that excessive leakage is generated in the alternating current circuit.

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