JP2006047121A - Earth fault detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an earth fault detector of a low cost and of low power consumption. <P>SOLUTION: The detector comprises a positive side peak detection part 4 for detecting a positive side peak value Vp1 for input waveform; a negative side peak detection part 5 for detecting a negative side peak value Vp2 for input waveform; a positive side comparator 6 for outputting detection signal Sd1 when the input waveform rises over a positive side threshold value; a negative side comparator 7 for outputting a detection signal Sd2 when the input waveform rises over a negative side threshold value; a clock part 8 for generating date and time data Dt; a memory part 10; and a control part 12 for storing the peak value Vp1 and polarity data Dpo indicating positive polarity when the detection signal Sd1 was input, together with measured date and time data Dmt in the memory 10, and the peak value Vp2 and polarity data Dpo indicating negative polarity when the detection signal Sd2 was input, together with measured date and time data Dmt in the memory 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ground fault detection device that detects a ground fault generated in a power line such as a high-voltage electric wire.

This type of ground fault detection apparatus is used in a system for specifying a section of occurrence of a ground fault (current generation) in a power line, for example, as disclosed in JP-A-9-159718. Specifically, the detailed configuration is not disclosed in the publication, but in general, the ground fault detection device is provided for each electric wire installed with a space between the power lines. The current flowing in the wire to be detected is detected by a current sensor, and when this current is detected, the detected current (or the voltage obtained by current / voltage conversion of this current) is A / D (analog / digital) converted and its waveform data Is stored in the memory. Therefore, the operator analyzes the waveform data stored in the memory of the local fault detection device disposed on each electric wire, and thereby the first peak value of the current detected at almost the same date and time in the local fault detection device. Based on (the peak value of the first wave) and the polarity of the peak value, it is possible to specify the occurrence section (current generation section) of the ground fault that occurred in the power line at this date and time.
JP-A-9-159718 (2nd page)

  However, the conventional ground fault detection apparatus has the following problems. That is, in this ground fault detection apparatus, the current at the time of occurrence of the ground fault accident is A / D converted and the waveform data obtained by the conversion is stored in the memory. In this case, in order to be able to accurately specify the peak value and polarity of this current, this current must be sampled and A / D converted at a very short period, and a high-speed A / D converter is required. I need it. In addition, since A / D conversion is performed with an extremely short period, a large amount of waveform data is stored in the memory, and thus a large-capacity memory is required. Therefore, since a high-speed A / D converter and a large-capacity memory are expensive and consume a lot of power, this ground fault detection device has a problem that the product price increases and the power consumption is large. .

  The present invention has been made in view of such problems, and a main object of the present invention is to provide a ground fault detection device that is inexpensive and has low power consumption.

  In order to achieve the above object, a ground fault detection apparatus according to claim 1, wherein a positive peak detection unit for detecting a positive peak value for an input waveform and a negative peak value for detecting a negative peak value for the input waveform are provided. A side peak detector; a positive side comparator that outputs a first detection signal when the input waveform rises above a positive threshold; and a second detection when the input waveform falls below a negative threshold. A negative comparison unit that outputs a signal, a clock unit that generates date and time data, a storage unit, and the peak value and positive polarity detected by the positive peak detection unit when the first detection signal is input And the polarity data indicating negative polarity are stored in the storage unit together with the date and time data, and the peak value detected by the negative peak detection unit when the second detection signal is input. Previous with date / time data And a control unit to be stored in the storage unit.

  The ground fault detection device according to claim 2 is the ground fault detection device according to claim 1, wherein the control unit calculates an effective value for the input waveform based on the detected peak value. The date and time data are stored in the storage unit.

  According to the ground fault detection device according to claim 1, the positive side peak detection unit, the negative side peak detection unit, the positive side comparison unit, the negative side comparison unit, and the clock unit are provided, and the control unit inputs the first detection signal. When the second detection signal is input, the peak value detected by the positive peak detection unit and the polarity data indicating the positive polarity are stored in the storage unit together with the date and time data, and detected by the negative peak detection unit. The peak value of the first wave and the polarity indicating the polarity of the current generated in the electric wire to which the ground fault detection device is attached are stored in the storage unit together with the date and time data and the polarity data indicating the negative polarity and the polarity data indicating the polarity. Data can be directly detected and stored in the storage unit without using a high-speed A / D converter and a large-capacity memory. Therefore, according to this ground fault detection device, it is possible to avoid the use of expensive and high power consumption electronic components such as a high-speed A / D converter and a large-capacity memory. Power consumption can be reduced. Further, according to the ground fault detection device, power consumption can be reduced. Therefore, when a configuration in which the battery is operated is adopted, the battery itself can be reduced in size while ensuring a desired continuous operation time. Can also be miniaturized. Therefore, the ground fault detection device can be easily attached to the electric wire provided on the power line and can be easily removed.

  In addition, according to the ground fault detection device of the second aspect, since the effective value of the current can be calculated, the occurrence section (current generation section) of the ground fault occurring in the power line based on the effective value is determined. Can be identified.

  The best mode of a ground fault detection apparatus according to the present invention will be described below with reference to the accompanying drawings.

  First, the configuration of the ground fault detection apparatus 1 will be described with reference to the drawings.

  As shown in FIG. 1, the ground fault detection device 1 includes a current sensor unit 2, an amplification unit 3, a positive peak detection unit 4, a negative peak detection unit 5, a positive comparison unit 6, a negative comparison unit 7, a watch The unit 8, the display unit 9, the storage unit 10, the operation unit 11, and the control unit 12 are configured to detect the current I flowing through the electric wire 14.

  As an example, the current sensor unit 2 includes a current transformer 2a and a resistor 2b. In this case, the current transformer 2a is attached to the electric wire 14 so that the electric wire 14 passes through the central portion thereof. The resistor 2b converts the current I detected by the current transformer 2a into a voltage Vs. The amplifying unit 3 amplifies the input voltage Vs with a preset amplification factor, and supplies a voltage signal (to the positive side peak detecting unit 4, the negative side peak detecting unit 5, the positive side comparing unit 6 and the negative side comparing unit 7). The input waveform in the present invention is output as Si. As an example, the amplification factor of the amplifying unit 3 is defined so that the voltage signal Si is 1 volt when the current I is 100 amperes.

  The positive peak detection unit 4 detects and holds the positive peak value Vp1 for the input voltage signal Si, and outputs the peak value Vp1 to the control unit 12. Further, when the reset signal Sr is input, the positive peak detection unit 4 resets the held peak value Vp1 to, for example, zero volts. The negative peak detector 5 detects and holds the negative peak value Vp2 for the input voltage signal Si, and outputs the peak value Vp2 to the controller 12. Further, when the reset signal Sr is input, the negative peak detection unit 5 also resets the held peak value Vp2 to, for example, zero volts in the same manner as the positive peak detection unit 4. In this case, the positive-side peak detection unit 4 and the negative-side peak detection unit 5 are so-called peak hold circuits, for example, a diode, a capacitor connected in series to the diode, and a capacitor connected in parallel to the capacitor. When the reset signal Sr is input, the circuit is configured by a known circuit including a reset switch element such as a transistor that is turned on to discharge the capacitor.

  The positive side comparison unit 6 is configured by a comparator as an example, compares the input voltage signal Si with a preset positive polarity threshold Vre1, and forms a pulse when the voltage signal Si rises above the positive polarity threshold Vre1. The detection signal (first detection signal in the present invention) Sd1 is output to the control unit 12. The negative side comparison unit 7 is configured by a comparator as an example, compares the input voltage signal Si with a preset negative polarity threshold value Vre2, and forms a pulse when the voltage signal Si falls below the negative polarity threshold value Vre2. The detection signal (second detection signal in the present invention) Sd2 is output to the control unit 12.

  The clock unit 8 is configured by a real time clock (RTC), for example, and outputs the date / time data Dt to the control unit 12. The display unit 9 is composed of, for example, an LCD and displays data input from the control unit 12. The storage unit 10 is composed of a ROM, a RAM, and the like, and stores an operation program for the control unit 12, and also includes a first wave peak value (peak current value Ip) for the current I, measurement date / time data Dmt, and Each of the polarity data Dpo is stored. The operation unit 11 includes an operation switch (not shown), and is configured to output a display command Dd to the control unit 12. The control unit 12 is configured by a CPU or the like and operates according to an operation program stored in the storage unit 10 to input a detection signal Sd1 or Sd2 and detect a peak value for the current I. Is executed to calculate the peak value (peak current value Ip) for the current I and specify the polarity data Dpo of the peak value, and the peak current value Ip and the polarity data Dpo together with the measurement date / time data Dmt. Store in the storage unit 10. Further, when the display command Dd is input from the operation unit 11, the control unit 12 detects the peak value (peak current value Ip) detected and specified for the current I generated in the past and the polarity data Dpo together with the measurement date / time data Dmt. The data is read from the storage unit 10 and displayed on the display unit 9.

  Next, the operation of the ground fault detection apparatus 1 will be described with reference to FIG.

  In the ground fault detection device 1, when the power is turned on, the control unit 12 outputs the reset signal Sr to the positive peak detection unit 4 and the negative peak detection unit 5, so that the positive peak detection unit 4 and The peak values Vp1 and Vp2 held by the negative peak detector 5 are reset. Thereafter, the positive peak detection unit 4 continuously detects the positive peak value Vp1 included in the input voltage signal Si. On the other hand, the negative peak detector 5 continuously detects the negative peak value Vp2 included in the input voltage signal Si. The positive side comparison unit 6 always monitors whether or not the input voltage signal Si has risen above the positive threshold value Vre1. On the other hand, the negative side comparison unit 7 always monitors whether or not the input voltage signal Si is lower than the negative polarity threshold Vre2. The control unit 12 repeatedly inputs the detection signals Sd1 and Sd2 each time the detection signals Sd1 and Sd2 are output from the comparison units 6 and 7, respectively.

  In this state, when the current I flows through the electric wire 14, a voltage Vs proportional to the current I is generated at both ends of the resistor 2 b connected to the current transformer 2 a of the current sensor unit 2. The amplifying unit 3 amplifies the voltage Vs with a predetermined amplification factor to generate a voltage signal Si. As shown in FIG. 1, the positive side peak detecting unit 4, the negative side peak detecting unit 5, and the positive side comparing unit 6 are used. The voltage signal Si is output to the negative comparison unit 7. In a state where no ground fault occurs, the current I is normally at a level where the frequency is the same as the commercial frequency (for example, 50 Hz) and the amplitude is low. For this reason, the voltage signal Si does not reach either the positive polarity threshold value Vre1 or the negative polarity threshold value Vre2. On the other hand, when a ground fault occurs, the amplitude of the current I increases rapidly. For this reason, as a result of the amplitude of the voltage signal Si abruptly increasing, the voltage signal Si includes a positive or negative first wave that first reaches either the positive threshold Vre1 or the negative threshold Vre2. Become. As an example, when a current I including a first wave (positive first wave) whose amplitude on the positive polarity side first increases suddenly flows through the electric wire 14, the voltage signal Si is as shown in FIG. A positive wave corresponding to the first wave of the current I (hereinafter also referred to as “the first wave of the voltage signal Si”) is included. In this case, the first wave of the voltage signal Si first rapidly rises to the peak value Vp1 exceeding the positive threshold value Vre1, and then rapidly drops toward 0 volts. The voltage signal Si shown in the figure includes a negative second wave generated following the first wave. Therefore, when the first wave of the voltage signal Si rises and crosses the positive polarity threshold Vre1, the positive side comparison unit 6 generates the detection signal Sd1 and outputs it to the control unit 12, and then the negative side comparison When the second wave of the voltage signal Si decreases and crosses the negative polarity threshold Vre2, the unit 7 generates the detection signal Sd2 and outputs it to the control unit 12. The positive peak detector 4 detects and holds the positive peak value Vp1 (first wave peak value) included in the input voltage signal Si, and the negative peak detector 5 receives the input voltage. A negative peak value Vp2 (second wave peak value) included in the signal Si is detected and held.

  When the control unit 12 inputs the earlier one of the detection signal Sd1 and the detection signal Sd2 in a state after resetting the positive peak detection unit 4 and the negative peak detection unit 5, the peak value for the current I The detection process is executed, the peak value (peak current value Ip) of the first wave included in the current I, the polarity data Dpo indicating the polarity of the peak value, and the measurement date / time data indicating the detection date and time of the current I Dmt is associated with and stored in the storage unit 10. Specifically, when the detection signal Sd1 or the detection signal Sd2 is input, which is earlier, the control unit 12 inputs the date / time data Dt from the clock unit 8 and stores it as measurement date / time data (time stamp) Dmt. Store in the unit 10. Next, the control unit 12 determines whether the detection signal Sd1 or the detection signal Sd2 is input earlier (according to whether the detection signal first input is the detection signal Sd1 or the detection signal Sd2). The polarity of the peak value of the first wave included in the current I is specified and stored in the storage unit 10 as the polarity data Dpo in association with the measurement date / time data Dmt. In this case, the control unit 12 specifies the polarity of the peak value of the first wave included in the current I as positive when the detection signal Sd1 is input earlier, and when the detection signal Sd2 is input earlier, The polarity of the peak value of the first wave included in the current I is specified as negative polarity.

  Next, the control unit 12 inputs the peak value Vp1 from the positive-side peak detection unit 4 when the specified polarity is positive, and inputs the peak value Vp2 from the negative-side peak detection unit 5 when the specified polarity is negative. Based on the input peak value Vp1 (or Vp2), the peak value (peak current value Ip) of the first wave for the current I is calculated. In this example, as described above, when the current I is 100 amperes, the amplification factor 3 is defined so that the voltage signal Si is 1 volt. Therefore, the control unit 12 has the peak current value Ip In the calculation, the peak value Vp1 captured from the positive peak detector 4 or the peak value Vp2 captured from the negative peak detector 5 is calculated as the peak current value Ip. In addition, the control unit 12 stores the calculated peak value (peak current value Ip) of the first wave for the current I in the storage unit 10 in association with the measurement date / time data Dmt. Finally, the control unit 12 resets the peak values Vp1 and Vp2 held by the positive peak detecting unit 4 and the negative peak detecting unit 5 by outputting a reset signal Sr. Thereby, the peak value detection process for one current I is completed. As an example, for the voltage signal Si shown in FIG. 2, since the first wave is a positive wave, the control unit 12 first inputs the detection signal Sd1. Therefore, the control unit 12 stores the polarity data Dpo indicating positive polarity and the positive peak value Vp1 (peak current value Ip) detected by the positive peak detection unit 4 in association with the measurement date / time data Dmt. 10 to store each. The control unit 12 repeatedly executes the above-described peak value detection process for the current I every time the current I is generated in the electric wire 14 until the power supply of the ground fault detection device 1 is turned off. The peak current value Ip, the polarity data Dpo, and the measurement date / time data Dmt are stored in the storage unit 10 in the order of the date / time indicated by the measurement date / time data Dmt.

  In addition to the waveform shown in FIG. 2, the voltage signal Si may be as shown in FIGS. 3 and 4, for example, depending on the current I. Specifically, the voltage signal Si shown in FIG. 3 is different in polarity between the first wave and the second wave, and has an absolute value of the peak value Vp2 of the second wave rather than the absolute value of the peak value Vp1 of the first wave. Will be bigger. In the voltage signal Si shown in FIG. 4, the second wave does not have a reverse polarity with respect to the first wave, and the first wave and the second wave have the same polarity. For any voltage signal Si, the control unit 12 identifies the first wave based on the type of signal (detection signal Sd1 or detection signal Sd2) initially input from the comparison units 6 and 7, and The first-wave polarity data Dpo and the peak value (peak current value Ip) are stored in the storage unit 10 in association with the measurement date / time data Dmt. Therefore, the control unit 12 accurately detects the peak value of the first wave that exceeds the positive polarity threshold Vre1 or falls below the negative polarity threshold Vre2 for the current I whose waveform varies in accordance with the state of the ground fault. And can be stored in the storage unit 10.

  On the other hand, when the display command Dd is input from the operation unit 11 to the control unit 12, the control unit 12 displays the peak current value Ip, the polarity data Dpo, and the measurement date / time data of the current I for the electric wire 14 stored in the storage unit 10. Dmt is read out and displayed on the display unit 9. Therefore, the operator can select the peak current value Ip, polarity data Dpo, and measurement date / time data Dmt that are automatically stored in the storage unit 10 by the local fault detector 1 disposed on each electric wire 14 of the power line. Based on the peak current value Ip and polarity data Dpo detected at substantially the same date and time, it is possible to specify the occurrence section (current generation section) of the ground fault that occurred in the power line at this date and time.

  As described above, according to the ground fault detection device 1, the positive side peak detection unit 4, the negative side peak detection unit 5, the positive side comparison unit 6, the negative side comparison unit 7, and the clock unit 8 are provided. When the detection signal Sd1 is input, the peak current value Ip of the first wave for the current I calculated based on the peak value Vp1 detected by the positive peak detection unit 4 and the polarity data Dpo indicating the positive polarity are obtained. The peak current value of the first wave for the current I calculated based on the peak value Vp2 detected by the negative peak detection unit 5 when it is stored in the storage unit 10 together with the measurement date / time data Dmt and the detection signal Sd2 is input. By storing Ip and polarity data Dpo indicating negative polarity in the storage unit 10 together with the measurement date / time data Dmt, the first wave of the current I generated in the electric wire 14 to which the ground fault detection device 1 is attached is stored. The chromatography leakage current value Ip and the polarity data Dpo indicating the polarity, without using a high-speed A / D converter and a large amount of memory can be stored directly detected and the storage unit 10. Therefore, according to the ground fault detection device 1, it is possible to avoid the use of expensive and high power consumption electronic components such as a high-speed A / D converter and a large-capacity memory, so that the product cost can be reduced. In addition, power consumption can be reduced. Moreover, according to this ground fault detection apparatus 1, since power consumption can be reduced, when the structure operated with a battery is adopted, the battery can be reduced in size while ensuring a desired continuous operation time. It can also be miniaturized. Therefore, for example, when the electric wire 14 is assumed to be a grounding electric wire, an aerial distribution electric wire, an indoor distribution electric wire, or other electric wires that carry an induced current such as a power line, etc. The ground fault detection device 1 can be easily attached to and removed from the electric wire.

  In addition, this invention is not limited to said structure. For example, an effective value (effective current value) Irms for the current I is calculated based on the input peak current value Ip, and the calculated effective value Irms is measured together with the peak current value Ip or in place of the peak current value Ip. The control unit 12 can also be configured so as to be stored in the storage unit 10 together with the date / time data Dmt. In this case, for example, the control unit 12 regards the waveform of the current I as a sine wave and calculates the effective value Irms by dividing the peak current value Ip by the square root of 2. With this configuration, it is possible to specify the occurrence section (current generation section) of the ground fault occurring in the power line based on the effective value Irms.

  The positive side comparison unit 6 and the negative side comparison unit 7 employ a configuration in which fixed values set in advance are used as the positive polarity threshold value Vre1 and the negative polarity threshold value Vre2, but instead of this configuration, A configuration in which arbitrary values set by the operation unit 11 and input via the control unit 12 are used as the positive polarity threshold value Vre1 and the negative polarity threshold value Vre2 may be employed. Further, a plurality of candidate values for the positive polarity threshold Vre1 and the negative polarity threshold Vre2 are stored in the storage unit 10 in advance, and any two of these candidate values displayed on the display unit 9 are stored in the operation unit 11. It is also possible to employ a configuration in which the two candidate values are specified by operation and are output from the control unit 12 to the positive side comparison unit 6 and the negative side comparison unit 7 as the positive threshold value Vre1 and the negative polarity threshold value Vre2. In this way, by adopting a configuration in which the positive polarity threshold value Vre1 and the negative polarity threshold value Vre2 can be arbitrarily set, the positive polarity threshold value is set to an optimum value for detecting the current I flowing through the electric wire for each arranged electric wire. Vre1 and negative polarity threshold value Vre2 can be set. Therefore, it is possible to detect the ground fault generated in the arranged electric wire more reliably. Specifically, as an example, when the maximum measured value of the current I that flows when a ground fault occurs (the maximum value of the peak current value Ip) is 200 A, five values of 1A, 4A, 7A, 10A, and 15A Can be used as candidate values for the positive polarity threshold value Vre1, and five values of -1A, -4A, -7A, -10A, and -15A can be used as candidate values for the negative polarity threshold value Vre2.

  Moreover, as shown in FIG. 1, the output part 13 comprised using light-emitting devices, such as sound generating apparatuses, such as a buzzer, and LED, can further be provided. In this configuration, when the control unit 12 completes the storage of the first wave peak current value Ip for the current I and the polarity data Dpo indicating the polarity in the storage unit 10, it generates sound and light. The output unit 13 is controlled. According to this configuration, as a result of the ground fault detection device 1 being able to recognize the detection completion of the peak current value Ip and the polarity data Dpo for the current I by sound or light, the worker can sufficiently perform the generation detection work for the current I. Can be made easier. When the appropriate level input to the set of the positive side peak detection unit 4 and the negative side peak detection unit 5 and the appropriate level input to the set of the positive side comparison unit 6 and the negative side comparison unit 7 are different, the voltage signal An amplifier can be provided that amplifies the Si voltage level to match either set of appropriate levels.

It is a block diagram which shows the structure of the ground fault detection apparatus. FIG. 5 is a waveform diagram showing an example of a general waveform of a voltage signal Si input to a positive side peak detection unit 4, a negative side peak detection unit 5, a positive side comparison unit 6 and a negative side comparison unit 7; It is a wave form diagram which shows another example of the waveform of the voltage signal Si input into the positive side peak detection part 4, the negative side peak detection part 5, the positive side comparison part 6, and the negative side comparison part 7. It is a wave form diagram which shows another example of the waveform of the voltage signal Si input into the positive side peak detection part 4, the negative side peak detection part 5, the positive side comparison part 6, and the negative side comparison part 7.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ground fault detection apparatus 4 Positive side peak detection part 5 Negative side peak detection part 6 Positive side comparison part 7 Negative side comparison part 8 Clock part 10 Storage part 12 Control part Dt Date and time data I Current Sd1, Sd2 Detection signal Si Voltage signal Si (Input waveform)
Vp1, Vp2 peak value

Claims (2)

A positive peak detector for detecting the positive peak value of the input waveform;
A negative peak detection unit for detecting a negative peak value for the input waveform;
A positive comparison section that outputs a first detection signal when the input waveform rises above a positive threshold;
A negative comparison unit that outputs a second detection signal when the input waveform falls below a negative threshold;
A clock section for generating date and time data;
A storage unit;
The peak value detected by the positive-side peak detection unit when the first detection signal is input and polarity data indicating positive polarity are stored in the storage unit together with the date / time data, and the second detection signal A ground fault detection device comprising: a control unit that stores the peak value detected by the negative peak detection unit and polarity data indicating a negative polarity in the storage unit together with the date / time data when the negative side peak detection unit is input.   The ground fault detection apparatus according to claim 1, wherein the control unit calculates an effective value for the input waveform based on the detected peak value and stores the effective value together with the date / time data in the storage unit.

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