KR100816101B1 - Earth-leakage device in live condition - Google Patents

Abstract

An earth leakage exploration device in a live state is disclosed. The device that detects the leakage of the ground line located between the ground transformer and the customer in a live state, the transmitter which applies the asymmetrical AC pulse wave to the ground transformer-the ground transformer has a waveform of a combination of the commercial power supply and the asymmetrical AC pulse wave Output a signal; And a ground signal including a signal component having a synthesized waveform from the ground of the detection point, and outputting a polarity value that is a potential difference at the detection point by using a signal output by filtering a signal having symmetry in the ground signal. Including the device, the polarity value determines whether there is a short circuit and the direction from the exploration point to the short circuit point. According to the present invention, the low voltage asymmetric AC pulse wave is used, so that even in the live state, the consumer-side electronic device is not affected.

Description

Earth leakage tester in live condition {APPARATUS FOR PINPOINTING SHORT CIRCUIT IN LIVE STATE}

1 is a diagram illustrating an earth leakage detecting method using a high voltage DC pulse wave according to the related art.

2 is a view showing the flow of the return current during the earth leakage detection in the live state according to the prior art.

3 is a graph illustrating the synthesis of an asymmetric AC pulse wave and a commercial power supply of a receiver according to an embodiment of the present invention.

Figure 4 is a view showing the return current flow during the earth leakage detection in the live state according to an embodiment of the present invention.

5 is a schematic diagram of an earth leakage exploration according to an embodiment of the present invention;

6 is a diagram illustrating receiver response and signal waveforms at the left and right sides of the ground fault point according to an exemplary embodiment of the present invention.

7 shows waveforms of an earth signal including a noise component according to the present invention;

8 is a block diagram showing a detailed configuration of a ground fault detecting receiver according to an embodiment of the present invention.

9 is a detailed block diagram of a signal discrimination unit configured in an internal circuit of a receiver according to an embodiment of the present invention.

10 is a circuit and waveform flow diagram when the receiver is located to the left of the ground fault point according to an embodiment of the present invention.

11 is a circuit and waveform flow diagram when the receiver is located to the right of the ground fault point according to an embodiment of the present invention.

The present invention relates to an earth leakage survey, and more particularly, to an earth leakage detecting apparatus in a live state.

Under the urban aesthetics, facilities and safety, underground laying of cables is underway in many areas, and the trend is expanding. There is always a risk of earthquake damage due to tension stress on ground subsidence and the damage caused by excavation work that occurs frequently, and the deterioration due to poor construction and long-term use.

If a short circuit occurs in a city road that is easily accessible by citizens, the risk of a safety accident is high because of a short circuit. Therefore, a short circuit is to be found and repaired immediately if a short circuit is detected. .

Conventionally, in order to search for an earth leakage point or an earth leakage section, the underground low voltage line is electrostatically disconnected at each section with an insulation resistance meter and the insulation resistance is checked to search for an earth leakage section, or the leakage current meter is checked along the line to check the magnitude of the leakage current. As a result, a method of determining a short circuit section has been used.

However, these methods are effective in detecting the leakage section, but they cannot pinpoint the location of the leakage. Therefore, when a short circuit occurs in the underground line (underground low voltage line), it is impossible to pinpoint the location of the leakage due to the invisibility and the lack of suitable equipment. Excavation was forced to repair.

In the event of a short circuit on the underground low voltage line, it is very urgent to develop a device capable of accurately detecting a short circuit in order to prevent various safety accidents that may occur and to solve a problem in which customer inconvenience and power sales are reduced.

In particular, it may be very efficient to detect a short circuit in a live state rather than a diagonal state, but in the prior art, a device for reliable short circuit detection in a live state has not been provided.

Here, the oblique state refers to a state in which power is not supplied to the underground low voltage line, and the live state refers to a state in which power is supplied.

Most earth leakage detectors developed to date have been developed by applying high-voltage DC pulses to a line to measure earth potential caused by ground faults or to detect magnetic flux. However, the earth potential measurement method uses a high voltage to catch the potential generated on the ground, and the magnetic flux is used in a live state, but all of them are developed indoors, and the magnetic flux measurement is a short circuit In one case, the error range is very large.

The main reason why the conventional earth leakage probe was forced to use a high voltage DC pulse method was that the earth leakage probe could not be designed with high sensitivity to extract a signal detected along with noise existing on the ground. .

In order to extract low signals, the more sensitive amplification is, the more the signal sources (wind, 60 Hz signal, earth shake, etc.) corresponding to noise are amplified together, and no matter how much the filter performance is improved, it is inevitable. Therefore, the high voltage DC pulse method has been used to exclude noise components from the input signal.

However, such a high voltage DC pulse method can be applied only in a diagonal state, as shown in FIG. 1 (FIG. 1 is a diagram illustrating a short circuit detecting method using a high voltage DC pulse wave according to the prior art). When a high voltage of 100V or more is applied while a commercial power supply of 60 Hz is supplied, the maximum voltage exceeds 400 V, the maximum allowable voltage that a surge protector built in an electronic device can withstand when synthesis occurs with the commercial power supply. This is because there is a risk of damage to electronic devices.

2 is a view showing the flow of the return current in the earth leakage detection in the live state according to the prior art. Referring to FIG. 2, in the case of earth leakage detection using a DC pulse signal in a live state, ground currents of Ia, Ib, and Ic are simultaneously generated, and a return current toward the electronic device is larger, such as Ia <Ib + Ic. As a result, it is impossible not only to damage the consumer's electronic equipment, but also to detect the short circuit accurately.

In other words, the high voltage DC pulse method is a technology that has a limit that is possible only in the diagonal state due to the influence of the consumer side in the live state.

In order to overcome this problem, the world is spurring the development of equipment to detect the earth leakage position in the live state, but there is no equipment that can be reliable among the devices capable of earth leakage detection.

Accordingly, the present invention has been devised to solve the above-described problem, and is intended to provide an apparatus capable of exploring a short circuit in a live state without affecting a consumer's electronic device.

Another object of the present invention is to use a receiver having a low voltage asymmetric AC pulse wave and a receiver having a built-in signal discriminator circuit, thereby preventing damage to electronic devices on the consumer side and preventing errors caused by various noises, It is to provide an earth leakage detecting device in a live state that can accurately detect a point.

It is another object of the present invention to provide a ground fault detecting apparatus in an active state capable of quickly and accurately detecting a ground fault point.

Other objects of the present invention will become more apparent through the preferred embodiments described below.

According to an aspect of the present invention for achieving the above object, a device for exploring a ground fault in the underground line located between the ground transformer and the customer in a live state, a transmitter for applying an asymmetrical AC pulse wave to the ground transformer- The ground transformer outputs a signal having a waveform of a commercial power supply and the asymmetric AC pulse wave; And a ground signal including a signal component having the synthesized waveform from the ground of the detection point, and filtering a signal having symmetry in the ground signal to obtain a polarity value that is a potential difference at the detection point using the output signal. Including a detection device for outputting, there is provided a ground fault detecting device in a live state, characterized in that whether the ground fault or the direction from the sensing point to the ground fault is determined according to the polarity value.

The asymmetric AC pulse wave may have a voltage in a range in which the synthesized waveform does not exceed the maximum allowable voltage of the electronic device connected to the consumer side.

In addition, the detection device, the ground signal input unit for receiving the ground signal; A filter unit to perform filtering to remove the commercial power and noise from the ground signal; And a signal discrimination unit configured to process the filtered signal to calculate a polarity value.

The apparatus may further include an amplifier for amplifying the signal filtered by the filter and transferring the signal to the signal discriminator.

The signal discrimination unit may include an inverting / AC removing unit configured to receive and invert the filtered signal and remove an AC component; An AC removal unit receiving the filtered signal and removing an AC component; A signal comparator for comparing the signals output from the inverting / AC removing unit and the AC removing unit; And an average value circuit unit outputting a DC value having a positive or negative value corresponding to the polarity by using the compared signal.

The signal comparator may subtract the signal output from the AC remover from the signal output from the invert / AC remover.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms including ordinal numbers such as first and second may be used to describe various components, but the components are not limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and in describing the present invention with reference to the accompanying drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicated thereto. The description will be omitted.

5 is a diagram illustrating a schematic diagram of an earth leakage exploration according to an exemplary embodiment of the present invention.

Referring to FIG. 5, an underground low voltage line is positioned between the ground transformer 503 and the customer 506, and the ground transformer 503 changes the voltage or current of an alternating current by using electromagnetic induction. Supply commercial power (60Hz, 220Vac) to each electronics of.

When a short circuit occurs between sections 503 and 506 of the underground cable line, a ground fault detecting device including a transmitter 501 and a receiver 505 is provided to detect a ground fault point.

The transmitter 501 according to the present invention generates and outputs a pulse wave for detecting an earth leakage point. The receiver 505 receives the ground signal output according to the combined signal of the pulse wave and the commercial power source, and performs a function to find a ground fault point by processing it. As shown in the figure, the receiver 505 has two electrodes connected to the ground, one of which is a reference electrode and the other of which is a detection electrode. The reference electrode is to make the reference potential on the ground and the receiver circuit equal to 0V between each other, and the detection electrode is for receiving a signal actually detected from the ground. Since the reference electrode and the detection electrode is a technology applied to a general electronic circuit, a detailed description thereof will be omitted.

Although three receivers 505 are shown in FIGS. 5 and 6, they use one receiver 505 to approach the ground fault point while moving the position of the receiver 505 (ie, changing the exploration point). To illustrate the example. That is, when exploring from the left side of the ground fault point, the probe points to the right, it can be recognized that the ground fault point is located on the right side of the exploration point. Detailed description thereof will be described later.

According to the present embodiment, the ground fault point detection is performed in the live state, and an asymmetric AC pulse wave may be used as shown in FIG. 5 for the ground fault detection in the live state.

As described above, the live state is a state in which power is supplied from the ground transformer 503 to the customer side.

On the other hand, in the present embodiment, the asymmetric AC pulse wave is a pulse wave in which the time periods in which the signal level is high and the low period in which pulses are alternately output are not equal to each other.

The application of asymmetric AC pulse waves for live leakage detection in the live state is that symmetrical AC pulse waves are often symmetric in the ground signal received from the receiver 505. This makes it impossible to interpret the signal.

In addition, it is preferable that the asymmetric AC pulse wave according to the present embodiment has a frequency of 50 V or less and 5 KHz, which is variously connected to the customer 506 even in a live state, that is, even when synthesis with 60 Hz and 220 Vac commercial power occurs. This is to accurately detect the earth leakage point without damaging the internal circuits of electronic devices such as refrigerators, computers and TVs.

That is, since the AC pulse wave according to the present embodiment has an asymmetric structure, there is a significant difference in frequency from a noise signal having symmetry and commercial power (220V, 60Hz). This frequency difference is detected on the ground including the frequency of commercial power and various noise components, which is the biggest technical problem when using low voltage signals that do not exceed Peak 50V as the earth leakage detection signal source. It provides a fundamental advantage to solve the disadvantage of not implementing a filtering circuit.

The voltage and frequency of the asymmetric AC pulse wave are for illustrative purposes, and are not necessarily limited thereto.

In FIG. 5, the transmitter 501 according to the present embodiment applies an asymmetric AC pulse signal through an asymmetric AC pulse wave through a line connected by separating a neutral point of the ground transformer 503, that is, a second type ground line. At this time, it is important to install the wires of the transmitter 501 first before releasing the ground transformer type 2 ground wire. If the type 2 ground wire is separated without the wires installed correctly, it may cause a serious problem for safety. Because it can. Here, the second type ground wire and the like will be apparent to those skilled in the art, and thus a detailed description thereof will be omitted.

Accordingly, as illustrated in FIG. 3, the ground transformer 503 generates a synthesized waveform obtained by synthesizing a commercial power source having an maximum peak voltage of −311 V to +361 V and an AC pulse wave.

The peak voltage of the synthesized waveform is important for live earth leakage detection because the varistor built in to protect the circuit inside the consumer electronics is not burned out and the maximum voltage that can withstand is less than 400V.

If a peak voltage of more than 400V is applied, various electronic devices on the customer side are damaged, and thus, another return current is generated, which causes the varistors of the electronic devices to be destroyed, thereby causing serious damage to the circuit.

Therefore, according to the present invention, when the voltage of the asymmetric AC pulse wave is combined with a commercial power supply, it is set within a range not exceeding 400 V, so that damage of the electronic device does not occur even in the short circuit exploration in the live state.

≒ 340V가 된다. 이러한 경우, 비대칭 AC 펄스파가 피크 50V이하가 되는 경우, 합성 파형의 최대 피크는 최악의 상황이 되더라도 340V + 50V = 390V가 되기 때문에 전자기기 내부에 존재하는 보호 회로를 파손시키지 않게 된다. On the other hand, Figure 3 is based on when the ideal commercial power is applied, in practice, the commercial power is sometimes applied up to 240Vac. If the commercial power supply is 240Vac, the maximum peak is 240Vac x

340V. In this case, when the asymmetric AC pulse wave is below the peak of 50V, the maximum peak of the synthesized waveform is 340V + 50V = 390V even in the worst case, so as not to break the protection circuit existing inside the electronic device.

According to the present embodiment, even if the earth leakage detection is performed in the live state, since the return current does not flow to the consumer side as shown in FIG. 4, the electronic device on the consumer side does not cause a problem.

According to an embodiment of the present invention, the receiver 505 may analyze a signal input from the ground and find out whether the current leaks and the exact current leakage point.

Since there are many noise components in the ground signal, the receiver 505 according to the present invention removes the noise components through filtering. Referring to FIG. 6, which illustrates a case where an earth leakage point survey is performed at left and right sides of a ground fault point, as shown by reference numerals 604 and FIG. 7, a fine noise component is included in a waveform in which a commercial power supply and an AC pulse wave are synthesized. That is, the receiver 505 removes noise components having symmetry through filtering.

In addition, the receiver 505 performs appropriate processing on the signal from which the noise component has been removed, thereby finally determining whether there is a short circuit through the average value of the DC component.

In this case, the average value of the DC component is a polarity value at the detection point, and when the polarity appears, the direction of the electric leakage may be recognized and thus the electric leakage point may be detected.

8 is a block diagram illustrating a detailed configuration of an earth leakage detecting receiver according to an exemplary embodiment of the present invention, and FIG. 8 is a diagram illustrating a detailed configuration of the receiver 505 illustrated in FIG. 5 in the earth leakage detecting apparatus.

As illustrated in FIG. 8, the earth leakage detecting apparatus according to the present invention may include a ground signal input unit 800, a filter unit 802, an amplifier unit 804, a signal determination unit 806, and a display unit 808. Can be.

The ground signal input unit 800 receives a ground signal of a waveform obtained by combining a commercial power source, a noise signal, and an AC pulse wave, as shown in FIG.

At this time, the ground signal is input as only a few kV ~ mV when viewed at the voltage level as shown in FIG. In addition, the ground signal is input as a waveform that can not be interpreted at all, including a large number of noise components such as wind, vehicle vibration, noise.

The filter unit 802 removes commercial power and noise components from the ground signal. Since the commercial power source and the noise component have symmetry, they are easily distinguished and easily removed by using the AC pulse signal having the asymmetry according to the present invention.

That is, a signal almost identical to the asymmetric AC pulse signal output from the transmitter 501 (that is, a waveform signal as shown in the filter unit 802 in FIG. 10) is obtained. Of course, passing through the filter circuit can eliminate most noise components having symmetry.

FIG. 10 is a circuit and waveform flowchart when the receiver is located to the left of the ground fault point according to an embodiment of the present invention, and the block diagram shown in FIG. 8 may be understood in more detail.

According to the embodiment shown in FIG. 10, the filter unit 802 may be a band pass filter (BPF) or a low pass filter (LPF) designed with high sensitivity. For example, when a ground fault detection is performed on the left side of the ground fault point, when the signal detected by the ground signal input unit 800 shown in FIG. 10 is filtered, the filter is filtered by the filter unit 802 as shown in FIG. 10. Signal can be obtained.

The amplifier 804 of FIG. 10 functions to amplify the signal to extract meaningful components from the filtered signal, and the signal discriminator 406 processes the amplified signal to determine whether there is a short circuit. That is, as described above, the signal discriminating unit 806 processes the filtered signal and outputs a polarity value having a positive or negative value. Therefore, the direction of the earth leakage point at the detection point can be recognized using the output polarity value.

An embodiment in which the signal discriminating unit 806 outputs a polarity value will be described.

9 is a diagram illustrating a detailed configuration of the signal discriminating unit 806 according to an embodiment of the present invention.

As shown in FIG. 9, the signal discriminating unit 806 according to the present invention includes an inverting / AC removing unit 902, a signal comparing unit 904, an average value circuit unit 906, and an AC removing unit 908. can do.

In order to understand the signal discriminating unit 806 in more detail, an embodiment of FIG. 10 will be described.

Looking at the signal determination unit 806 of FIG. 10, it can be seen that the signals transmitted through the amplifier 804 are respectively transmitted to the AC remover 908 and the invert / AC remover 902.

Here, the AC removal means completely removing the AC component from the signal transmitted from the amplifier 804. In order to explain this easily, the entire input signal is placed on the receiver circuit so that the input signal has only a positive voltage. It is a technology to raise the circuit power more than the reference power supply (0V).

The inverting / AC removing unit 902 means to invert the signal transmitted from the amplifying unit 804 and to have only a positive voltage by using a circuit according to AC removing.

The signal comparison unit 904 compares (ie, subtracts) the signals output from the inverting / AC removing unit 902 and the AC removing unit 908 shown in FIG. Outputs a signal as shown in FIG.

The reason why the signals output from the inverting / AC removing unit 902 and the AC removing unit 908 are compared with each other is to allow the receiver to have a direction toward the leaking point when the left side of the leakage point is the right side. The circuit used for this purpose is a subtraction circuit, and the AC removing unit 908 must be subtracted from the circuit based on the inversion / AC removing unit 902. The reason why the subtraction circuit is not constituted in the opposite case is that it does not have a directivity toward the leakage point and has a reverse direction.

The waveform output by the average value circuit section 906 has a polarity value of (+) or (-) (eg, has a negative value when the receiver is located to the right of the leakage point as shown in FIG. 11). ). Here, the polarity represents the potential difference at the detection point, and this potential difference appears when a short circuit occurs. Through this, it is possible to determine whether a short circuit exists, and the DC value calculated by the average value circuit unit 906 is output through the display unit 808.

When located at the right side of the leaking point, the circuit and signal flow chart as shown in FIG. 11 are provided, and thus the direction of the leaking point is left.

10 shows that the signal detected on the ground may have both (+) or (-) polarity through the subtraction circuit, but has a (+) polarity value among them. Here, to have a polarity means to have a direction, and according to the direction to move to the left or right in accordance with the direction of the meter to finally find a more accurate leakage point through the process of approaching the leakage point.

11 shows a case in which the polarity value is negative.

Here, the above-described embodiment is a case illustrating a case in which the meter reacts to the right side, and the case in which the meter reacts to the left side may be easily inferred by those skilled in the art through the above description.

As described above, since the present invention uses an asymmetric AC pulse wave having a low voltage source as an exploration signal in the live state, the electronic device on the consumer side compared with the conventional method in which the exploration signal has to be stronger than the noise signal to detect a short circuit Accurate earth leakage detection is possible without damaging the system. In addition, it is possible to overcome the limitations of the oblique earth leakage detection device in which the conventional high voltage DC pulse wave has to be used.

The present invention is not limited to the above-described embodiment, and many variations are possible by those skilled in the art within the spirit of the present invention.

As described above, according to the present invention, short-circuit detection is possible in a live state because a low voltage asymmetric AC pulse wave is used.

In addition, according to the present invention, since the low voltage asymmetric AC pulse wave is used, there is an advantage that the consumer-side electronic device is not affected even in the live state.

In addition, according to the present invention, it is possible to accurately and quickly find the leakage point through the asymmetric AC pulse wave, thereby preventing the material and time loss that occurs when the cable is replaced to the part where there is no leakage.

In addition, according to the present invention, even the influence of the noise component which may remain fine, which is the biggest technical problem when using a low voltage signal source, can be eliminated, so that a more accurate earth leakage detection can be performed in a live state.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art that various modifications of the present invention without departing from the spirit and scope of the invention described in the claims below And can be changed.

Claims (6)

It is a device for exploring in live state the leakage of underground cableway located between ground transformer and customer. A transmitter for applying an asymmetric AC pulse wave to the ground transformer, wherein the ground transformer outputs a signal having a waveform obtained by combining a commercial power supply and the asymmetric AC pulse wave; And Receive the ground signal at the detection point between the sections of the underground cable line and process the received signal to output a DC value having a (+) or (-) value, and correspond to the output (+) or (-) value A detection device for detecting an earth leakage point located in a direction from the exploration point to the ground transformer point or in the direction from the exploration point to the receiver street, The detection device A ground signal input unit for receiving the ground signal; A filter unit to perform filtering to remove the commercial power and noise from the ground signal; An inverting AC removal unit receiving the inverted filtered signal and inverting the AC signal; An AC removal unit receiving the filtered signal and removing an AC component; A signal comparator for subtracting the signal output from the AC remover from the signal output from the inverted AC remover; And And a mean value circuit unit for outputting a DC value having a positive or negative value which is the subtracted signal. The method of claim 1, The asymmetric AC pulse wave does not exceed a maximum 400V earth leakage detection device, characterized in that. delete The method of claim 1, And an amplifier for amplifying the signal filtered by the filter unit and transferring the amplified signal to the inverted AC remover and the AC remover. delete delete

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