JP2012200052A - Leak determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leak determination device that can quickly identify a heavy ground and a lightning surge.SOLUTION: The leak determination device includes: a zero phase current transformer 10 through which an AC circuit passes; a leak determination section 20 for determining whether or not the AC circuit leaks from an output voltage of the zero phase current transformer 10; an interruption signal output section 40 for outputting an interruption signal for interrupting the AC circuit if the leak determination section 20 determines that there occurs a leak; and a short time overvoltage detection section 30 for changing the leak determination system of the leak determination section 20 if the output voltage of the zero phase current transformer 10 reaches the absolute value of an overvoltage detection threshold th1 in a predetermined time.

Description

  The present invention relates to a leakage determination device. In particular, the present invention relates to a leakage determination device 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. 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.

  As a leakage case in which a leakage current is detected, there are three possible states: normal leakage, heavy ground fault, and lightning surge. The normal leakage indicates a leakage having a relatively small current value. A heavy ground fault refers to a leakage in which the current value of the leakage current is relatively large and the current value periodically appears. Lightning surge refers to a leakage in which the current value of the leakage current is relatively large and the current value appears temporarily.

  Of the three types of electric leakage, in the case of normal electric leakage and heavy ground fault, it is expected that electric leakage will occur for a long time, so it is preferable to immediately cut off the power supply via the AC electric circuit. On the other hand, in the case of a lightning surge, only a short circuit occurs, so it is not preferable to cut off the power supply via the AC circuit for each lightning surge.

  As a conventional earth leakage breaker, an earth leakage breaker capable of preventing unnecessary interruption due to lightning surge is known (for example, see Patent Document 1). This earth leakage breaker distinguishes a ground fault current due to a lightning surge or a heavy ground fault from the earth leakage current by a third comparator having a threshold larger than that of the first comparator for detecting the earth leakage current. Furthermore, a 3-wave counter detects whether more than 3 pulses are output from the first comparator during the time gate period created by the monostable multivibrator activated by the output of the third comparator. Distinguish between lightning surge and heavy ground fault. Thereby, the interruption signal is output from the interruption signal output circuit only in the case of a ground fault and a heavy ground fault.

Japanese Patent Laid-Open No. 10-094161

  However, in the earth leakage breaker disclosed in Patent Document 1, in any case, it is necessary to count the earth leakage current having a relatively large current value three times in order to distinguish between lightning surge and heavy ground fault. is there. In the case of a heavy ground fault, there is a possibility that the leakage current will flow continuously. Therefore, it is preferable to determine whether or not it is a heavy ground fault more quickly from the viewpoint of human body protection or the like.

  This invention is made | formed in view of the said situation, Comprising: It aims at providing the ground-fault determination apparatus which can identify a heavy ground fault and a lightning surge rapidly.

  In order to solve the above-described problem, the leakage determination device of the present invention includes a zero-phase current transformer through which an AC circuit passes, and whether or not a leakage occurs in the AC circuit from the output voltage of the zero-phase current transformer. A leakage determining unit for determining the leakage current, a blocking signal output unit for outputting a blocking signal for blocking the AC circuit when the leakage determining unit determines that leakage has occurred, and the zero-phase current transformer A short-time overvoltage detection unit that changes a leakage determination method by the leakage determination unit when the output voltage of the first voltage reaches outside the first predetermined voltage range within a predetermined time.

  In the present invention, the short-time excessive voltage detection unit includes an excessive voltage detection unit that detects an excessive voltage in which an output voltage of the zero-phase current transformer is outside the first predetermined voltage range; A steep wave detection unit that detects a steep wave whose differential value of the output voltage of the fluency is equal to or greater than a predetermined value, and an overvoltage is detected by the overvoltage detection unit, and a steep wave is detected by the steep wave detection unit A leakage determination method changing unit that changes a leakage determination method by the leakage determination unit.

  In the present invention, the short-time excessive voltage detection unit includes a diode unit in which a plurality of diodes are inserted in parallel with the zero-phase current transformer in opposite directions, and an output voltage of the diode unit is the first voltage. A diode voltage detection unit that changes a leakage determination method by the leakage determination unit when the voltage is out of a predetermined voltage range.

  Further, in the present invention, the short-time excessive voltage detection unit detects a leakage determination process by the leakage determination unit when the output voltage of the zero-phase current transformer reaches the outside of the first predetermined voltage range within a predetermined time. Delay time.

  Moreover, in this invention, the leakage current detection unit outputs a predetermined voltage when the output voltage of the zero-phase current transformer is outside a second predetermined voltage range smaller than the first predetermined voltage. And an integration unit that integrates the output voltage of the leakage current detection unit, and an integration voltage that is an output voltage of the integration unit is equal to or higher than a third predetermined voltage that is equal to or higher than the second predetermined voltage. An integral value determination unit that determines that the output has occurred, and the short-time overvoltage detection unit detects that the output voltage of the zero-phase current transformer has exceeded the first predetermined voltage range within a predetermined time. The output voltage of the integrator is reduced.

  Moreover, in this invention, the leakage current detection unit outputs a predetermined voltage when the output voltage of the zero-phase current transformer is outside a second predetermined voltage range smaller than the first predetermined voltage. And an integration unit that integrates the output voltage of the leakage current detection unit, and an integration voltage that is an output voltage of the integration unit is equal to or higher than a third predetermined voltage that is equal to or higher than the second predetermined voltage. An integral value determination unit that determines that the output has occurred, and the short-time overvoltage detection unit detects that the output voltage of the zero-phase current transformer has exceeded the first predetermined voltage range within a predetermined time. In this case, the third predetermined voltage is increased.

  According to the present invention, the leakage determination unit includes a count addition unit that adds 1 count when the output voltage of the zero-phase current transformer is outside a second predetermined voltage range that is smaller than the first predetermined voltage. When the leakage determination method is changed by the leakage determination method change unit, the count subtraction unit for subtracting one count, the count added by the count addition unit, and the count subtracted by the count subtraction unit are integrated. A count integration unit that outputs an integrated value, and a count determination unit that determines that a leakage has occurred when the integrated value output by the count integration unit is greater than or equal to a predetermined value.

  Also, in the present invention, the short time excessive voltage detection unit is output by the count integration unit when the output voltage of the zero-phase current transformer reaches the outside of the first predetermined voltage range within a predetermined time. Decrease the integrated value.

  Further, in the present invention, the short-time excessive voltage detecting unit reaches outside the first predetermined voltage range within a predetermined time, and the output voltage of the zero-phase current transformer is higher than the first predetermined voltage. When the state that is outside the fourth predetermined voltage range that is smaller and larger than the second predetermined voltage continues for a predetermined time or longer, the leakage determination method by the leakage determination unit is changed.

  Moreover, in this invention, after changing the leakage determination method by the leakage determination unit by the short time excessive voltage detection unit, the output voltage of the zero-phase current transformer is smaller than the first predetermined voltage. A second overvoltage detection unit that detects a second overvoltage that is outside a fifth predetermined voltage range that is greater than a predetermined voltage, and wherein the cutoff signal output unit determines that leakage has occurred by the leakage determination unit If the second overvoltage is detected by the second overvoltage detector, the cutoff signal is output.

  Further, in the present invention, an overvoltage continuation detection unit that detects that the state in which the second overvoltage is detected by the second overvoltage detection unit continues for a predetermined time or more is provided, and the cutoff signal output unit includes the When the leakage determination unit determines that leakage has occurred, or when the excessive voltage continuation detection unit detects that the state of the second excessive voltage has continued for a predetermined time or more, the interruption signal is output. To do.

  Further, in the present invention, a resistor section that divides the output voltage of the zero-phase current transformer is provided, and the short-time overvoltage output section has a first predetermined voltage within a predetermined time when the voltage divided by the resistor section is within a predetermined time. When the voltage is outside the voltage range, the leakage determination method by the leakage determination unit is changed.

  According to the present invention, it is possible to quickly identify a heavy ground fault and a lightning surge.

The circuit block diagram which shows the structural example of the earth-leakage determination apparatus in the 1st Embodiment of this invention The circuit block diagram which shows the detailed structural example of the short time excessive voltage detection part in the 1st Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 1 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the structural example of the leak determination apparatus in the 2nd Embodiment of this invention The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 4 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 1st structural example of the leak determination apparatus in the 3rd Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 6 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 2nd structural example of the leak determination apparatus in the 3rd Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 8 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 1st structural example of the leak determination apparatus in the 4th Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 10 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 2nd structural example of the leak determination apparatus in the 4th Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 12 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 1st structural example of the leak determination apparatus in the 5th Embodiment of this invention The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 14 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 2nd structural example of the leak determination apparatus in the 5th Embodiment of this invention The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 16 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 1st structural example of the leak determination apparatus in the 6th Embodiment of this invention. The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 18 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 2nd structural example of the leak determination apparatus in the 6th Embodiment of this invention The figure which shows an example of the waveform of the output signal which each circuit of the earth leakage determination apparatus shown in FIG. 20 outputs in the case of each scene (normal earth leakage, heavy ground fault, lightning surge) The circuit block diagram which shows the 1st structural example of the leak determination apparatus in the 7th Embodiment of this invention The circuit block diagram which shows the 2nd structural example of the leak determination apparatus in the 7th Embodiment of this invention

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

(First embodiment)
FIG. 1 is a block diagram showing a configuration example of a leakage determination device according to the first embodiment of the present invention. The earth leakage determination device 100 shown in FIG. 1 includes a zero-phase current transformer 10, an earth leakage determination unit 20, a short-time overvoltage detection unit 30, and a cutoff signal output unit 40. Note that each component of the leakage determination device 100 of the present embodiment is configured by an analog circuit.

  The zero-phase current transformer 10 includes an annular core (core) made of a magnetic material such as a soft magnetic material that penetrates a plurality of primary conductors that constitute an AC circuit through which a three-phase current flows. And a toroidal coil. When a difference occurs between the current flowing in the forward direction of the AC circuit and the current flowing in the return direction, the zero-phase current transformer 10 generates a leakage current based on the difference. An induced voltage corresponding to the leakage current is generated at both ends of the coil. The zero-phase current transformer 10 outputs this induced voltage as a ZCT output voltage that is an output voltage of the zero-phase current transformer 10 to the leakage determination unit 20 and the short-time overvoltage detection unit 30. Further, in order to obtain a voltage output from the zero-phase current transformer 10, a resistance element is inserted in parallel with the zero-phase current transformer 10.

  The leakage determination unit 20 determines whether or not a leakage has occurred in the AC circuit. The leakage determination unit 20 includes a leakage current detection unit 21, an integration unit 22, and an integration value determination unit 23.

  The leakage current detection unit 21 is configured by a comparator or the like, and detects that a leakage current has occurred. Here, leakage current detection unit 21 outputs voltage H (High) to integration unit 22 when the absolute value of the ZCT output voltage is equal to or greater than the absolute value of leakage current detection threshold th2. On the other hand, when the absolute value of the ZCT output voltage is less than the leakage current detection threshold th2, the voltage L (Low) is output to the integrating unit 22. The voltage H is higher than the voltage L.

  The integrating unit 22 is configured by an integrator or the like, integrates the output voltage of the leakage current detecting unit 21, and outputs the integrated voltage (integrated voltage) to the integrated value determining unit 23 as an output voltage.

  Further, the integration unit 22 changes the leakage determination method in the leakage determination unit 20 when the output voltage of the short time excessive voltage detection unit 30 (here, the output voltage of the leakage determination method change unit 33) is the voltage H. . When changing the leakage determination method, for example, when the integration unit 22 detects that the output voltage of the short-time overvoltage detection unit 30 is the voltage H, the integration value (integration voltage) is decreased by a predetermined value. Further, the integrating unit 22 may increase the integrated value determination threshold th3 by a predetermined value instead of decreasing the integrated value by a predetermined value. By changing the leakage determination method, the time width of the time for integrating the voltage value of the ZCT output voltage is increased. That is, the short circuit overvoltage detection unit 30 delays the leakage determination processing by the leakage determination unit 20.

  Based on the integrated value that is the integrated output voltage of the integrating unit 22 and the output voltage of the short-time excessive voltage detecting unit 30, the integrated value determining unit 23 determines whether or not a leakage has occurred. Here, the integral value determination unit 23 outputs the voltage H to the cutoff signal output unit 40 when the integrated value is equal to or greater than the integral value determination threshold th3. On the other hand, when the integrated value is less than the integrated value determination threshold th3, the voltage L is output to the cutoff signal output unit 40. The fact that the output voltage of the integral value determination unit 23 is the voltage H corresponds to the determination that leakage has occurred.

  The short time excessive voltage detection unit 30 detects that an excessive ZCT output voltage is generated in a predetermined short time. For example, when the ZCT output voltage reaches outside the predetermined voltage range within a predetermined time, the leakage determination method by the leakage determination unit 20 is changed. The short time overvoltage detection unit 30 includes an overvoltage detection unit 31, a steep wave detection unit 32, and a leakage determination method change unit 33. The lightning surge is detected by the short time excessive voltage detection unit 30.

  As shown in detail in FIG. 2, the overvoltage detection unit 31 is configured by a comparator (window comparator) or the like, and when the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the overvoltage detection threshold th1, The voltage H is output to the changing unit 33. On the other hand, when the absolute value of the ZCT output voltage is less than the absolute value of the overvoltage detection threshold th1, the voltage L is output to the leakage determination method changing unit 33.

  The absolute value of the overvoltage detection threshold th1 is larger than the absolute value of the leakage current detection threshold t2. Further, the integral value determination threshold th3 is larger than the absolute value of the leakage current detection threshold t2. The integrated value determination threshold th3 is, for example, a value such that the integrated voltage becomes larger than the integrated value determination threshold th3 when the voltage H is detected twice as the output voltage of the leakage current detection unit 21 without changing the leakage determination method. It is.

  As shown in detail in FIG. 2, the steep wave detection unit 32 is configured by a differentiator (differentiating circuit) or the like, and differentiates the ZCT output voltage. Then, when the differentiated voltage is equal to or higher than the steep wave detection threshold, the steep wave detection unit 32 outputs the voltage H to the leakage determination method change unit 33. On the other hand, when the differentiated voltage is less than the steep wave detection threshold, the voltage L is output to the leakage determination method changing unit 33.

  The leakage determination method changing unit 33 is configured by an AND circuit or the like, and the voltage is supplied to the integration unit 22 of the leakage determination unit 20 according to the logical product of the output voltage of the overvoltage detection unit 31 and the output voltage of the steep wave detection unit 32. H or L is output. Specifically, when both the output voltage of the overvoltage detection unit 31 and the output voltage of the steep wave detection unit 32 are the voltage H, the output voltage of the leakage determination method changing unit 33 is the voltage H. In other cases, the output voltage of the leakage determination method changing unit 33 is the voltage L. The fact that the output voltage of the leakage determination method changing unit 33 is the voltage H means that the short-time excessive voltage detection unit 30 has detected a lightning surge, and further, the leakage determination method by the leakage determination unit 20 is changed. means.

  The cutoff signal output unit 40 is configured by a comparator or the like, and outputs the voltage H when the output voltage of the integral value determination unit 23 is the voltage H. On the other hand, when the output voltage of the integral value determination unit 23 is the voltage L, the voltage L is output. That is, when the leakage signal determination unit 20 determines that leakage has occurred, the interruption signal output unit 40 outputs the interruption signal for opening the electric circuit contact of the AC electric circuit (for interrupting the AC electric circuit). It is sent to a tripping coil (not shown) that opens the electric circuit contact.

Next, the operation of the leakage determination device 100 will be described.
FIG. 3 is a time chart for explaining an operation example of the leakage determination device 100.

  The “leakage current” in FIG. 3 indicates the leakage current generated in the zero-phase current transformer 10 in each case (normal leakage, heavy ground fault, lightning surge). As shown in FIG. 3, in the case of normal leakage, a leakage current having a relatively small current value is generated, and in the case of a heavy ground fault, a relatively large and periodic leakage current is generated. In some cases, the current value is relatively large and a temporary leakage current is generated.

  “ZCT output” in FIG. 3 indicates the output voltage (ZCT output voltage) of the zero-phase current transformer 10 corresponding to the leakage current in each case.

  The “overvoltage detector output” in FIG. 3 indicates the output voltage of the overvoltage detector 31 in each case. In the case of a lightning surge, the output voltage of the overvoltage detection unit 31 becomes the voltage H when the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the overvoltage detection threshold th1 (+ th1, −th1).

  The “steep wave detection unit output” in FIG. 3 indicates the output voltage of the steep wave detection unit 32 in each case. In the case of a lightning surge, when the output voltage of the steep wave detection unit 32 becomes equal to or higher than the steep wave detection threshold (the steep wave detection threshold is not shown), the output voltage of the steep wave detection unit 32 becomes the voltage H.

  The “leakage determination method changing unit output” in FIG. 3 indicates the output voltage of the leakage determination method changing unit 33 in each case. In the case of a lightning surge, both the output voltage of the overvoltage detection unit 31 and the output voltage of the steep wave detection unit 32 become the voltage H, so that the output voltage of the leakage determination method change unit 33 becomes the voltage H.

  The “leakage current detection output” in FIG. 3 indicates the output voltage of the leakage current detection unit 21 in each case. In each of normal leakage, heavy ground fault, and lightning surge, when the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the leakage current detection threshold th2 (+ th2, -th2), the output voltage of the leakage current detection unit 21 is The voltage becomes H.

  “Integration output” in FIG. 3 indicates the output voltage of the integration unit 22 in each case. In the case of a lightning surge, when the output voltage of the leakage determination method changing unit 33 becomes the voltage H, the integrating unit 22 decreases the integrated value by a predetermined value. Therefore, in the case of a lightning surge, the timing at which the integral value becomes equal to or greater than the integral value determination threshold th3 is delayed as compared with the case of normal electric leakage or heavy ground fault.

  “Interrupt signal output” in FIG. 3 indicates the output voltage of the interrupt signal output unit in each case. In the case of normal earth leakage and heavy ground fault, the output voltage of the cutoff signal output unit 40 becomes the voltage H when the integral value is equal to or greater than the integral value determination threshold th3. On the other hand, in the case of a lightning surge, since the integrated value remains below the integrated value determination threshold th3, the output voltage of the cutoff signal output unit 40 remains at the voltage L.

  According to the interruption determination apparatus 100 of the present embodiment as described above, in the case of a lightning surge, the integral value is less likely to become equal to or greater than the integral value determination threshold th3 due to the action of the short-time overvoltage detection unit 30. That is, when the short time excess detection unit 30 determines that the lightning surge has occurred, the output voltage of the leakage determination method changing unit 33 becomes the voltage H. Therefore, the integration unit 22 to which the voltage H is input is, for example, at the time of input. Decrease the integral value of. Therefore, in the case of a lightning surge, when the number of times that the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the leakage current detection threshold th2 is, for example, three times or more, the cutoff signal output unit 40 outputs a cutoff signal.

  On the other hand, in the case of normal leakage and heavy ground fault, when the number of times that the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the leakage current detection threshold th2 is less than the lightning surge, for example, twice or more, The output signal is output from the output unit 40.

  As described above, in the case of a heavy ground fault, when a ZCT output voltage equal to or higher than a predetermined value is detected twice, the power supply by the AC circuit is interrupted, so that human body protection and the like can be reliably performed. In the case of a lightning surge, if the ZCT output voltage exceeding a predetermined value is detected three times, the power supply by the AC circuit is interrupted, so that the AC circuit is difficult to be interrupted, and every time a lightning surge occurs, the AC circuit The situation where the power supply is cut off can be avoided.

(Second Embodiment)
FIG. 4 is a block diagram illustrating a configuration example of a leakage determination device according to the second embodiment of the present invention. The leakage determination device 100B shown in FIG. 4 includes a zero-phase current transformer 10, a leakage determination unit 20, a short-time overvoltage detection unit 30B, and a cutoff signal output unit 40. That is, the configuration other than the short-time excessive voltage detection unit 30B is the same as the leakage determination device 100 illustrated in FIG. Here, the short-time overvoltage detection unit 30B will be mainly described, and the description of other configurations will be omitted or simplified.

  The zero-phase current transformer 10 outputs the ZCT output voltage to the leakage determination unit 20 and the short-time overvoltage detection unit 30B.

  The short time excessive voltage detection unit 30B detects that an excessive ZCT output voltage is generated in a predetermined short time. For example, when the ZCT output voltage reaches outside the predetermined voltage range within a predetermined time, the leakage determination method by the leakage determination unit 20 is changed. The short-time excessive voltage detection unit 30B includes a diode unit 34 and a diode voltage detection unit 35. Lightning surge is detected by the short-time excessive voltage detector 30B.

  As shown in FIG. 4, the diode unit 34 includes a pair of diodes arranged in parallel to each other in parallel with the zero-phase current transformer 10. Note that the number of diodes is at least two. Each diode of the diode section 34 allows current to flow only in one direction from the anode to the cathode only when the voltage is equal to or higher than a predetermined voltage (diode slice voltage th5, for example, 1 V). Therefore, the diode unit 34 does not pass current when the ZCT output voltage is smaller than the diode slice voltage th5, such as normal leakage. Further, when the ZCT output voltage is larger than the diode slice voltage th5, such as a heavy ground fault or a lightning surge, the diode unit 34 passes a current. As a result, in the case of a heavy ground fault, the voltage input to the diode voltage detector 35 is smaller (sliced) than the ZCT output voltage.

  Here, since the diode portion 34 is formed of a semiconductor element, a slight time lag occurs between the time when the ZCT output voltage becomes equal to or higher than the diode slice voltage th5 and the time when the current flows. For this reason, in the case of a lightning surge, an excessive voltage (steep wave) is generated in a short time as described above. Therefore, the diode section 34 does not pass a current when a lightning surge occurs due to the characteristics of the diode. Therefore, when the lightning surge occurs, an excessive voltage is generated, but the ZCT output voltage input to the diode voltage detection unit 35 is not sliced.

  The diode voltage detection unit 35 is configured by a comparator or the like, and outputs a voltage H to the integration unit 22 of the leakage determination unit 20 when the ZCT output voltage is equal to or higher than the diode voltage detection threshold th4 in the subsequent stage of the diode unit 34. . On the other hand, when the ZCT output voltage is less than the diode voltage detection threshold th4, the voltage L is output to the integrating unit 22 of the leakage determining unit 20. Outputting the voltage H corresponds to changing the leakage determination method by the leakage determination unit 20.

  The diode voltage detection threshold th4 is larger than the diode slice voltage th5 and corresponds to the overvoltage detection threshold th1 in the first embodiment. The diode slice voltage th5 is larger than the absolute value of the leakage current detection threshold th2.

Next, the operation of the leakage determination device 100B will be described.
FIG. 5 is a time chart for explaining an operation example of the leakage determination device 100B. Description of the same content as that described in FIG. 3 is omitted or simplified.

  “ZCT output” in FIG. 5 indicates the output voltage (ZCT output voltage) of the zero-phase current transformer 10 corresponding to the leakage current in each case. This ZCT output voltage indicates a state sliced by the diode unit 34 as necessary. In the case of a heavy ground fault, the ZCT output voltage is sliced when the ZCT output voltage is equal to or higher than the diode slice voltage th5. In the case of a lightning surge, a ZCT output voltage equal to or higher than the diode slice voltage th5 is generated, but the ZCT output voltage is not sliced because of a steep wave.

  “Diode voltage detector output” in FIG. 5 indicates the output voltage of the diode voltage detector 35 in each case. In the case of a lightning surge, the output voltage of the diode voltage detector 35 becomes the voltage H when the ZCT output voltage becomes equal to or higher than the diode voltage detection threshold th4.

  “Integration output” in FIG. 5 indicates the output voltage of the integration unit 22 in each case. In the case of a lightning surge, when the output voltage of the diode voltage detection unit 35 reaches the voltage H, the integration unit 22 decreases the integration value by a predetermined value. Therefore, in the case of a lightning surge, the timing at which the integral value becomes equal to or greater than the integral value determination threshold th3 is delayed as compared with the case of normal electric leakage or heavy ground fault.

  According to the interruption determination device 100B of the present embodiment as described above, in the case of a lightning surge, the integral value is less likely to become equal to or greater than the integral value determination threshold th3 due to the action of the short-time overvoltage detection unit 30B. That is, when the short time excessive detection unit 30B determines that the lightning surge has occurred, the output voltage of the diode voltage detection unit 35 becomes the voltage H. Therefore, the integration unit 22 to which the voltage H is input is, for example, at the input time point. Decrease the integral value. Therefore, in the case of a lightning surge, when the number of times that the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the leakage current detection threshold th2 is, for example, three times or more, the cutoff signal output unit 40 outputs a cutoff signal.

  On the other hand, in the case of normal leakage and heavy ground fault, when the number of times that the absolute value of the ZCT output voltage is equal to or greater than the absolute value of the leakage current detection threshold th2 is less than the lightning surge, for example, twice or more, The output signal is output from the output unit 40.

  As described above, in the case of a heavy ground fault, when a ZCT output voltage equal to or higher than a predetermined value is detected twice, the power supply by the AC circuit is interrupted, so that human body protection and the like can be reliably performed. In the case of a lightning surge, if a ZCT output voltage of a predetermined level or more is detected three times, the power supply by the AC circuit is cut off, so that the power supply by the AC circuit is cut off every time a lightning surge occurs. Can be avoided.

  Furthermore, since the operational amplifier for the comparator and the operational amplifier for the differentiator are unnecessary by using the diode unit 34, the circuit configuration of the interruption determination device 100B becomes easy.

(Third embodiment)
FIG. 6 is a block diagram illustrating a configuration example of a leakage determination device according to the third embodiment of the present invention. The leakage determination device 100C1 shown in FIG. 6 includes a zero-phase current transformer 10, a leakage determination unit 20C, a short-time overvoltage detection unit 30C1, and a cutoff signal output unit 40. That is, the configuration other than the leakage determination unit 20C and the short-time excessive voltage detection unit 30C1 is the same as the leakage determination device 100 illustrated in FIG. Here, leakage determination unit 20C and short-time overvoltage detection unit 30C1 will be mainly described, and description of other configurations will be omitted or simplified. Note that a digital circuit is used as a component of the leakage determination device 100C1 of the present embodiment.

  The zero-phase current transformer 10 outputs the ZCT output voltage to the leakage determination unit 20C and the short-time overvoltage detection unit 30C1.

  The leakage determination unit 20C determines whether or not a leakage has occurred in the AC circuit. The leakage determination unit 20 </ b> C includes a leakage current detection unit 21, a count addition unit 24, a count integration unit 26, and a count comparison unit 27.

  The count adding unit 24 is configured by an adder or the like of a digital circuit, and adds “1” each time a voltage value equal to or higher than a predetermined voltage is input. That is, the count adding unit 24 outputs “+1” to the count integrating unit 26. Therefore, the count addition unit 24 outputs “+1” when the output voltage of the leakage current detection unit 21 is equal to or higher than the predetermined voltage. Here, when the output voltage of leakage current detection unit 21 is voltage H, it is designed to be equal to or higher than a predetermined voltage, and when the output voltage of leakage current detection unit 21 is voltage L, it is designed to be less than the predetermined voltage.

  The count integration unit 26 is configured by an adder or the like of a digital circuit, and adds and stores the output value of the count addition unit 24 and the output value of the count subtraction unit 37 of the short-time excessive voltage detection unit 30C1. The initial value of the count integration unit 26 is “0”. That is, the count integration unit 26 functions as a digital counter. For example, when the output value “−1” of the count subtraction unit 37 of the short-time excessive voltage detection unit 30C1 is input, the stored value of the count integration unit 26 is subtracted by “1”. When the output value “+1” of the count adding unit 24 is input, the stored value of the count integrating unit 26 is added by “1”.

  The count comparison unit 27 includes a digital circuit, and compares the output value (stored value) of the count integration unit 26 with the count threshold th6. The predetermined value is “2”, for example. The count comparison unit 27 outputs “1” when the output value of the count integration unit 26 is equal to or greater than a predetermined value. On the other hand, when the output value of the count integration unit 26 is less than the predetermined value, “0” is output. The output value of the count comparison unit 27 being “1” corresponds to determining that a leakage has occurred.

  The short time excessive voltage detection unit 30D1 detects that an excessive ZCT output voltage is generated in a predetermined short time. For example, when the ZCT output voltage reaches outside the predetermined voltage range within a predetermined time, the leakage determination method by the leakage determination unit 20 is changed. The short-time excessive voltage detection unit 30D1 includes an excessive voltage detection unit 31, a steep wave detection unit 32, a leakage determination method change unit 33, and a count subtraction unit 37. Lightning surge is detected by the short-time excessive voltage detection unit 30D1.

  The count subtraction unit 37 is configured by a subtractor of a digital circuit or the like, and subtracts “1” every time a voltage value higher than a predetermined voltage is input. That is, the count subtraction unit 37 outputs “−1” to the count integration unit 26 of the leakage determination unit 20C. Therefore, the count subtraction unit 37 outputs “−1” when the output voltage of the leakage determination method changing unit 33 is equal to or higher than a predetermined voltage. Thereby, the leakage determination method by the leakage determination unit 20C is changed. Here, it is designed so that when the output voltage of leakage detection method changing unit 33 is voltage H, the voltage is equal to or higher than a predetermined voltage, and when the output voltage of leakage detection method changing unit 33 is voltage L, it is less than the predetermined voltage.

  The absolute value of the count threshold th6 is “2”, for example, and corresponds to the integral value determination threshold th3 described in the first embodiment.

Next, the operation of the leakage determination device 100C1 will be described.
FIG. 7 is a time chart for explaining an operation example of the leakage determination device 100C1. Description of the same content as that described in FIG. 3 is omitted or simplified.

  “Count subtraction unit output” in FIG. 7 indicates the output value of the count subtraction unit 37 in each case. In the case of a lightning surge, since the output voltage of the leakage determination method changing unit 33 is the voltage H, the input voltage of the count subtracting unit 37 is equal to or higher than a predetermined voltage, and the output value of the count subtracting unit 37 is “−1”.

  “Count integration unit output” in FIG. 7 indicates an output value of the count integration unit 26 in each case. In each case, the count integration unit 26 adds 1 count when the output value “+1” of the count addition unit 24 is input. In the case of a lightning surge, since the output value “−1” of the count subtracting unit 37 is input, one count is subtracted when the output value is input. Therefore, in the case of a lightning surge, the timing at which the output value of the count integration unit 26 becomes equal to or greater than the count threshold th6 is delayed as compared to the case of normal leakage or heavy ground fault.

  “Interrupt signal output” in FIG. 7 indicates the output voltage of the interrupt signal output unit in each case. In the case of normal earth leakage and heavy ground fault, the output voltage of the cutoff signal output unit 40 becomes the voltage H when the output value of the count integration unit 26 becomes equal to or greater than the count threshold th6. On the other hand, in the case of a lightning surge, since the output value of the count integration unit 26 remains below the count threshold th6, the output voltage of the cutoff signal output unit 40 remains at the voltage L.

  According to such a leakage determination device 100C1 of the present embodiment, in addition to the effects described in the first embodiment, since the leakage determination unit 20C uses a digital circuit, for example, temperature characteristics are improved. The accuracy of leakage determination is improved. That is, heavy ground faults and lightning surges can be identified with higher accuracy.

  In addition, as shown in FIG. 8, the short-time overvoltage detection unit 30C1 of the leakage determination device 100C1 is replaced with the short-time overvoltage detection unit 30C2 using the diode described in the second embodiment, and the leakage determination device 100C2 May be configured. Further, FIG. 9 is a time chart showing an output example of each part in the case of a configuration like the leakage determination device 100C2.

(Fourth embodiment)
FIG. 10 is a block diagram illustrating a configuration example of a leakage determination device according to the fourth embodiment of the present invention. A leakage determination device 100D1 shown in FIG. 10 includes a zero-phase current transformer 10, a leakage determination unit 20, a short-time overvoltage detection unit 30D1, and a cutoff signal output unit 40. That is, the configuration other than the short-time excessive voltage detection unit 30D1 is the same as the leakage determination device 100 illustrated in FIG. Here, the short-time excessive voltage detection unit 30D1 will be mainly described, and the description of other configurations will be omitted or simplified.

  The short time excessive voltage detection unit 30D1 detects that an excessive ZCT output voltage is generated in a predetermined short time. For example, when the ZCT output voltage reaches outside the predetermined voltage range within a predetermined time, the leakage determination method by the leakage determination unit 20 is changed. The short-time excessive voltage detection unit 30D1 includes an excessive voltage detection unit 31, a steep wave detection unit 32, a leakage determination method change unit 33, and a continuation voltage detection unit 36. Lightning surge is detected by the short-time excessive voltage detection unit 30D1.

  The continuity voltage detection unit 36 is configured by a comparator or the like, and outputs a voltage H to the leakage determination method changing unit 33 when the state where the ZCT output voltage is equal to or greater than the continuation voltage detection threshold th7 continues for a predetermined time or more. . On the other hand, when the ZCT output voltage is less than the continuation voltage detection threshold th7 or the ZCT output voltage is equal to or more than the continuation voltage detection threshold th7 but the state does not continue for a predetermined time or more, the leakage determination method change unit A voltage L is output to 33. The predetermined time here is, for example, about ¼ of the power cycle of the AC power source connected to the primary conductor of the zero-phase current transformer 10. The continuity voltage detection unit 36 can detect a continuity voltage due to a lightning surge, and can distinguish a mere instantaneous noise from a lightning surge.

  The leakage determination method changing unit 33 is configured by an AND circuit or the like, and according to the logical product of the output voltage of the overvoltage detection unit 31, the output voltage of the steep wave detection unit 32, and the output voltage of the continuous voltage detection unit 36. The voltage H or L is output to the integration unit 22 of the leakage determination unit 20. Specifically, when the output voltage of the overvoltage detection unit 31, the output voltage of the steep wave detection unit 32, and the output voltage of the continuation voltage detection unit 36 are all the voltage H, the leakage determination method change unit 33 The output voltage of H becomes a voltage H. In other cases, the output voltage of the leakage determination method changing unit 33 is the voltage L. The fact that the output voltage of the leakage determination method changing unit 33 is the voltage H means that the short-time overvoltage detection unit 30 has detected a lightning surge.

  Note that the absolute value of the continuous voltage detection threshold th7 is larger than the absolute value of the leakage current detection threshold th2 and smaller than the absolute value of the overvoltage detection threshold th1.

Next, the operation of the leakage determination device 100D1 will be described.
FIG. 11 is a time chart for explaining an operation example of the leakage determination device 100D1. Description of the same content as that described in FIG. 3 is omitted or simplified.

  The “continuous voltage detector output” in FIG. 11 indicates the output voltage of the continuous voltage detector 36 in each case. In the case of a heavy ground fault and a lightning surge, the state in which the ZCT output voltage is equal to or greater than the continuity voltage detection threshold th7 continues for a predetermined time or more, and therefore the output voltage of the continuity voltage detection unit 36 is the voltage H.

  The “leakage determination method changing unit output” in FIG. 11 indicates the output voltage of the leakage determination method changing unit 33 in each case. In the case of a lightning surge, when all of the output voltage of the overvoltage detector 31, the output voltage of the steep wave detector 32, and the output voltage of the continuation voltage detector 36 become the voltage H, the leakage determination method changing unit 33 The output voltage becomes the voltage H. On the other hand, in the case of a heavy ground fault, the output voltage of the continuous voltage detector 36 may become the voltage H, but the output voltage of the overvoltage detector 31 and the output voltage of the steep wave detector 32 do not become the voltage H. The output voltage of the leakage determination method changing unit 33 remains the voltage L.

  “Integral output” in FIG. 11 indicates the output voltage of the integrating unit 22 in each case. In the case of a lightning surge, when the output voltage of the leakage determination method changing unit 33 becomes the voltage H, the integrating unit 22 decreases the integrated value by a predetermined value. Therefore, in the case of a lightning surge, the timing at which the integral value becomes equal to or greater than the integral value determination threshold th3 is delayed as compared with the case of normal electric leakage or heavy ground fault. Furthermore, the output voltage of the continuity voltage detection unit 36 becomes the voltage H after a predetermined time has elapsed since the occurrence of a steep wave due to a lightning surge. Compared to the case where the continuation voltage detection unit 36 is not provided. The timing for decreasing the integral value is delayed. Therefore, signals with similar characteristics but not lightning surges, such as instantaneous overvoltage noise, can be distinguished from lightning surges with high accuracy. In the case of noise, a cut-off signal is output immediately. In the case of a lightning surge, it is possible not to output a cut-off signal.

  According to such a leakage determination device 100D1 of the present embodiment, in addition to the effects described in the first embodiment, it takes a predetermined time to determine a lightning surge, thereby delaying the timing for reducing the integral value. Can do. Therefore, even if it is noise having an overvoltage and steep wave characteristic like the lightning surge, it can be reliably distinguished from the lightning surge.

  As shown in FIG. 12, the leakage determination device 100D2 may be configured by replacing the short-time excessive voltage detection unit 30D1 of the leakage determination device 100D1 with a short-time excessive voltage detection unit 30D2 using a diode. FIG. 13 is a time chart showing an output example of each part in the case of a configuration like the leakage determination device 100D2.

(Fifth embodiment)
FIG. 14 is a block diagram illustrating a configuration example of a leakage determination apparatus according to the fifth embodiment of the present invention. The leakage determination device 100E1 shown in FIG. 14 includes a zero-phase current transformer 10, a leakage determination unit 20, a short-time overvoltage detection unit 30D1, a cutoff signal output unit 40, a second overvoltage detection unit 50, a logical sum calculation unit 60, It is comprised. That is, the configuration other than the second overvoltage detection unit 50 and the logical sum calculation unit 60 is the same as the leakage determination device 100D1 illustrated in FIG. Here, the second overvoltage detection unit 50 and the logical sum calculation unit 60 will be mainly described, and description of other configurations will be omitted or simplified. In addition, although the short time excessive voltage detection part 30D1 of this embodiment is equipped with the 1st excessive voltage detection part 31 instead of the excessive voltage detection part 31, since both are the same in terms of content, the same code | symbol is attached | subjected. .

  The second overvoltage detection unit 50 includes a comparator or the like, and after the output voltage of the short-time overvoltage detection unit 30D1 becomes the voltage H, the absolute value of the ZCT output voltage is the absolute value of the second overvoltage detection threshold th8. When the value is equal to or greater than the value, the voltage H is output to the logical sum calculation unit 60. On the other hand, when the absolute value of the ZCT output voltage is less than the absolute value of the second overvoltage detection threshold th8, the voltage L is output to the OR calculation unit 60.

  The absolute value of the second overvoltage detection threshold th8 is equal to or greater than the absolute value of the continuation voltage detection threshold th6 and is equal to or less than the absolute value of the first overvoltage detection threshold (overvoltage detection threshold) th1.

  The OR calculation unit 60 is configured by an OR circuit or the like. When the output voltage of the integral value determination unit 23 or the output voltage of the second overvoltage detection unit 50 is the voltage H, the logical sum calculation unit 60 supplies the voltage H to the cutoff signal output unit 40. Output. On the other hand, when both the output voltage of the integral value determination unit 23 and the output voltage of the second overvoltage detection unit 50 are the voltage L, the voltage L is output to the cutoff signal output unit 40.

Next, the operation of the leakage determination device 100E1 will be described.
FIG. 15 is a time chart for explaining an operation example of the leakage determination device 100E1. Description of the same content as that described in FIG. 11 is omitted or simplified.

  The “first excessive detection unit output” in FIG. 15 indicates the output voltage of the first excessive voltage detection unit 31 in each case, and is the same as the “excess detection unit output” described in FIG. .

  “Second excessive detection unit output” in FIG. 15 indicates the output voltage of the second excessive voltage detection unit 50 in each case. In the case of a heavy ground fault, an excessive voltage periodically appears unlike a lightning surge, but the absolute value of the ZCT output voltage is the second absolute value exceeding the absolute value of the second excessive voltage detection threshold th8. The output voltage of the second overvoltage detection unit 50 becomes the voltage H.

  “Interrupt signal output” in FIG. 15 indicates the output voltage of the interrupt signal output unit 40. Even if the integrated value does not reach the integrated value determination threshold th3, when the output voltage of the second overvoltage detection unit 50 becomes the voltage H, the output voltage of the cutoff signal output unit 40 becomes the voltage H.

  According to the leakage determination device 100E1 of this embodiment, in addition to the effects described in the fourth embodiment, a heavy ground fault occurs when the second overvoltage is detected by the second overvoltage detection unit 50. The cutoff signal output unit 40 can output a cutoff signal before the output voltage of the integral value determination unit 23 becomes the voltage H. Therefore, it is considered that the larger the leakage current due to the heavy ground fault, the greater the influence on the human body. However, the power supply via the AC electric circuit can be stopped immediately, and the human body can be protected.

  In addition, as shown in FIG. 16, the short-term overvoltage detection unit 30D1 of the leakage determination device 100E1 may be replaced with a short-time overvoltage detection unit 30D2 using a diode to configure the leakage determination device 100E2. FIG. 17 is a time chart showing an output example of each part in the case of a configuration like the leakage determination device 100E2.

(Sixth embodiment)
FIG. 18 is a block diagram illustrating a configuration example of a leakage determination device according to the sixth embodiment of the present invention. An earth leakage determination device 100F1 shown in FIG. 18 includes a zero-phase current transformer 10, an earth leakage determination unit 20, a short-time overvoltage detection unit 30D1, a cutoff signal output unit 40, a second overvoltage detection unit 50, a logical sum calculation unit 60, An overvoltage continuation detecting unit 70 is provided. That is, the configuration other than the excessive voltage continuation detection unit 70 is the same as the leakage determination device 100E1 illustrated in FIG. Here, the excessive voltage continuation detection unit 70 will be mainly described, and description of other components will be omitted or simplified.

  The overvoltage continuation detection unit 70 is configured by a comparator or the like, and outputs a voltage H to the OR calculation unit 60 when a state where the ZCT output voltage is equal to or greater than the second overvoltage detection threshold th8 continues for a predetermined time or more. . That is, when the state where the output voltage of the second overvoltage detection unit 50 is the voltage H continues for a predetermined time or longer, the output voltage of the overvoltage continuation detection unit 70 becomes the voltage H. On the other hand, when the ZCT output voltage is less than the second overvoltage detection threshold th8 or the ZCT output voltage is greater than or equal to the second overvoltage detection threshold th8 but the state does not continue for a predetermined time or more, the logical sum is calculated. The voltage L is output to the unit 60. The predetermined time here is, for example, about ¼ of the power cycle of the AC power source connected to the primary conductor of the zero-phase current transformer 10. The overvoltage continuation detecting unit 70 can detect a continuous voltage due to a heavy ground fault, and can distinguish between a mere instantaneous noise and a heavy ground fault.

  The OR calculation unit 60 is configured by an OR circuit or the like, and outputs the voltage H to the cutoff signal output unit 40 when the output voltage of the integral value determination unit 23 or the output voltage of the overvoltage continuation detection unit 70 is the voltage H. To do. On the other hand, when both the output voltage of the integral value determination unit 23 and the output voltage of the overvoltage continuation detection unit 70 are the voltage L, the voltage L is output to the cutoff signal output unit 40.

Next, the operation of the leakage determination device 100F1 will be described.
FIG. 19 is a time chart for explaining an operation example of the leakage determination device 100F1. Description of the same content as that described in FIG. 15 is omitted or simplified.

  The “excessive voltage continuation detection unit output” in FIG. 19 indicates the output voltage of the overvoltage continuation detection unit 70 in each case. In the case of a heavy ground fault, unlike a lightning surge, an excessive voltage appears regularly. It is the second time that the absolute value of the ZCT output voltage becomes equal to or greater than the absolute value of the second overvoltage detection threshold th8, and when the state continues for a predetermined time or more, the output voltage of the overvoltage continuation detection unit 70 is The voltage becomes H. Therefore, when compared with the leakage determination device 100E1 of the fifth embodiment, the timing at which the interruption signal is output by the interruption signal output unit 40 is delayed.

  According to such a leakage determination device 100F1 of the present embodiment, as compared with the case where the second overvoltage detection unit 50 and the overvoltage continuation detection unit 70 are not provided, it is immediately recognized that a heavy ground fault has occurred. Can do. Moreover, if instantaneous noise is superimposed on the heavy ground fault, the heavy ground fault is erroneously determined as a lightning surge, and the leakage determination method may be changed so that the leakage determination is difficult. Even in such a case, by providing the excessive voltage continuation detection unit 70, it is possible to reliably recognize a heavy ground fault.

  As shown in FIG. 20, the short-circuit overvoltage detection unit 30D1 of the leakage determination device 100F1 may be replaced with a short-time overvoltage detection unit 30D2 using a diode to configure the leakage determination device 100F2. Further, FIG. 21 is a time chart showing an output example of each part in the case of a configuration like the leakage determination device 100F2.

(Seventh embodiment)
FIG. 22 is a block diagram illustrating a configuration example of a leakage determination device according to the seventh embodiment of the present invention. 22 includes a zero-phase current transformer 10, a leakage determination unit 20, a short-time overvoltage detection unit 30, a cut-off signal output unit 40, a first resistance unit 80, and a second resistance unit 90. Configured. That is, the configuration other than the first resistance unit 80 and the second resistance unit 90 is the same as the leakage determination device 100 illustrated in FIG. Here, the first resistance unit 80 and the second resistance unit 90 will be mainly described, and description of other configurations will be omitted or simplified.

  Resistor parts such as the first resistor part 80 and the second resistor part 90 are each composed of a resistance element and the like, and divide the ZCT output voltage. In other words, if an excessive voltage is input to the excessive voltage detector 31 due to a heavy ground fault or a lightning surge, there is a possibility that the electronic circuit in the subsequent stage may be destroyed, but the electronic circuit is protected by dividing the ZCT output voltage. can do. In addition, the resistance part for voltage division is not restricted to two.

  The short-time excessive voltage detection unit 30 causes the voltage divided by the first resistance unit 80 and the second resistance unit 90 to be outside the predetermined voltage range (here, the absolute value of the excessive voltage detection threshold th1 or more) within a predetermined time. If it is, the leakage determination method by the leakage determination unit 20 is changed.

Next, the operation of the leakage determination device 100G1 will be described.
A time chart for explaining an operation example of the leakage determination device 100G1 is the same as FIG. However, since the ZCT output voltage is divided, the ZCT output voltage decreases accordingly.

  According to such a leakage determination device 100G1 of this embodiment, by providing the first resistance unit 80 and the second resistance unit 90, even if a heavy ground fault or a lightning surge occurs, short-time overvoltage detection is performed. Each electronic circuit of the unit 30 can be protected. In addition, since it is possible to protect each electronic circuit of the short-time excessive voltage detection unit 30 from excessive voltage without giving pressure resistance, circuit cost can be reduced.

  As shown in FIG. 23, the leakage determination device 100G2 may be configured by replacing the short-time excessive voltage detection unit 30 of the leakage determination device 100G1 with a short-time excessive voltage detection unit 30B using a diode.

100, 100B, 100C, 100D1, 100D2, 100E1, 100E2, 100F1, 100F2, 100G1, 100G2 Leakage determination device 10 Zero-phase current transformer (ZCT)
20, 20C leakage determination device,
21 Current leakage detection unit 22 Integration unit 23 Integration value determination unit 24 Count addition unit 26 Count integration unit 27 Count comparison unit 30, 30B, 30C1, 30C2, 30D1, 30D2, Short time overvoltage detection unit 31 Overvoltage detection unit 32 Steep Wave detection unit 33 Leakage determination method change unit 34 Diode unit 35 Diode voltage detection unit 36 Continuous voltage detection unit 37 Count subtraction unit 40 Break signal output unit 50 Second overvoltage detection unit 60 Logical sum calculation unit 70 Overvoltage continuation detection unit 80 1st resistance part 90 2nd resistance part th1 Overvoltage detection threshold (1st overvoltage detection threshold)
th2 Leakage current detection threshold th3 Integration value determination threshold th4 Diode voltage detection threshold th5 Diode slice voltage th6 Count threshold th7 Continuous voltage detection threshold th8 Second overvoltage detection threshold

Claims (12)

A zero-phase current transformer through which the AC circuit passes,
A leakage determination unit that determines whether or not a leakage has occurred in the AC circuit from the output voltage of the zero-phase current transformer,
When it is determined by the leakage determining unit that leakage has occurred, a blocking signal output unit that outputs a blocking signal for blocking the AC electric circuit,
When the output voltage of the zero-phase current transformer reaches outside the first predetermined voltage range within a predetermined time, the short-time overvoltage detection unit that changes the leakage determination method by the leakage determination unit;
A leakage determination device comprising: The leakage determination device according to claim 1,
The short time overvoltage detector is
An overvoltage detection unit for detecting an overvoltage in which an output voltage of the zero-phase current transformer is outside the first predetermined voltage range;
A steep wave detector for detecting a steep wave whose differential value of the output voltage of the zero-phase current transformer is a predetermined value or more;
When an overvoltage is detected by the overvoltage detection unit, and when a steep wave is detected by the steep wave detection unit, a leakage determination method change unit that changes a leakage determination method by the leakage determination unit;
A leakage determination device comprising: The leakage determination device according to claim 1,
The short time overvoltage detector is
A diode unit in which a plurality of diodes are inserted in parallel with the zero-phase current transformer in opposite directions;
When the output voltage of the diode unit is outside the first predetermined voltage range, a diode voltage detection unit that changes a leakage determination method by the leakage determination unit;
A leakage determination device comprising: The electric leakage determination device according to any one of claims 1 to 3,
The short-time overvoltage detection unit is configured to delay the leakage determination process by the leakage determination unit when the output voltage of the zero-phase current transformer reaches outside the first predetermined voltage range within a predetermined time. apparatus. The leakage determination device according to claim 4,
The leakage determination unit
A leakage current detector that outputs a predetermined voltage when the output voltage of the zero-phase current transformer is outside a second predetermined voltage range that is smaller than the first predetermined voltage;
An integration unit for integrating the output voltage of the leakage current detection unit;
An integration value determination unit that determines that a leakage has occurred when an integration voltage that is an output voltage of the integration unit is equal to or higher than a third predetermined voltage that is equal to or higher than the second predetermined voltage;
With
The short-time excessive voltage detection unit is a leakage determination device that reduces the output voltage of the integration unit when the output voltage of the zero-phase current transformer reaches the outside of the first predetermined voltage range within a predetermined time. The leakage determination device according to claim 4,
The leakage determination unit
A leakage current detector that outputs a predetermined voltage when the output voltage of the zero-phase current transformer is outside a second predetermined voltage range that is smaller than the first predetermined voltage;
An integration unit for integrating the output voltage of the leakage current detection unit;
An integration value determination unit that determines that a leakage has occurred when an integration voltage that is an output voltage of the integration unit is a third predetermined voltage that is equal to or higher than the second predetermined voltage;
With
The short-term excessive voltage detection unit is a leakage determination device that increases the third predetermined voltage when the output voltage of the zero-phase current transformer reaches the outside of the first predetermined voltage range within a predetermined time. The leakage determination device according to any one of claims 1 to 4,
The leakage determination unit
When the output voltage of the zero-phase current transformer is outside a second predetermined voltage range smaller than the first predetermined voltage, a count adding unit that adds 1 count;
When the leakage determination method is changed by the leakage determination method change unit, a count subtraction unit that subtracts 1 count,
A count integration unit that integrates the count added by the count addition unit and the count subtracted by the count subtraction unit, and outputs an integrated value;
When the integrated value output by the count integrating unit is a predetermined value or more, a count determining unit that determines that a leakage has occurred,
A leakage determination device comprising: The leakage determination device according to claim 7,
The short-time excessive voltage detection unit is configured to reduce an integrated value output by the count integration unit when the output voltage of the zero-phase current transformer reaches outside the first predetermined voltage range within a predetermined time. Judgment device. The leakage determination device according to any one of claims 1 to 8,
The short-time overvoltage detection unit reaches the outside of the first predetermined voltage range within a predetermined time, and the output voltage of the zero-phase current transformer is smaller than the first predetermined voltage. A leakage determination device that changes a leakage determination method by the leakage determination unit when a state outside a fourth predetermined voltage range that is greater than the voltage continues for a predetermined time or longer. The electric leakage determination device according to claim 9, further comprising:
After changing the leakage determination method by the leakage determination unit by the short time excessive voltage detection unit, the output voltage of the zero-phase current transformer is smaller than the first predetermined voltage and larger than the fourth predetermined voltage. A second overvoltage detector that detects a second overvoltage that is outside a predetermined voltage range of 5,
The cutoff signal output unit outputs the cutoff signal when it is determined by the leakage determination unit that leakage has occurred, or when the second excessive voltage is detected by the second excessive voltage detection unit. Leakage determination device. The leakage determination device according to claim 10, further comprising:
An overvoltage continuation detection unit that detects that the state in which the second overvoltage is detected by the second overvoltage detection unit continues for a predetermined time or more;
The interruption signal output unit detects that the leakage has occurred by the leakage determination unit or that the state of the second excessive voltage has continued for a predetermined time or longer by the excessive voltage continuation detection unit. A leakage determination device that outputs the interruption signal in the case of failure. The leakage determination device according to any one of claims 1 to 11, further comprising:
Comprising a resistance section for dividing the output voltage of the zero-phase current transformer,
The short-term overvoltage output unit is a leakage determination device that changes a leakage determination method by the leakage determination unit when a voltage divided by the resistor reaches a first predetermined voltage range within a predetermined time.

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