KR20060110850A - Apparatus for pinpointing short circuit in live state and method thereof - Google Patents

Abstract

A method and an apparatus for detecting a current leakage in an activated electric line are provided to prevent electronic devices at a receiver side by using a low-voltage asymmetrical AC pulse wave. An apparatus for detecting a current leakage in an activated electric line between a transformer and a receiver includes a transmitter(301) and a detector(305). The transmitter applies an asymmetrical AC pulse wave on a ground line, which is connected to an N-phase of the transformer. The transformer outputs a signal with a waveform, which is formed by combining the asymmetrical AC pulse wave with a commercial source voltage. The detector receives a ground signal containing a signal component having the combined waveform, processes the ground signal, and outputs a polarity value at a measuring point. The current leakage is determined according to the polarity value.

Description

Circulation device for live leakage and its leakage detection method {APPARATUS FOR PINPOINTING SHORT CIRCUIT IN LIVE STATE AND METHOD THEREOF}

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

Figure 4 is a block diagram showing the detailed configuration of the earth leakage detecting device according to an embodiment of the present invention.

5 is a block diagram showing a detailed configuration of a signal determining unit according to an embodiment of the present invention.

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

FIG. 7 is a diagram illustrating a return current flow when an earth leakage is detected in a live state according to an exemplary embodiment of the present invention. FIG.

8 is a flow chart of a short circuit exploration process in a live state according to the present invention.

9 illustrates waveforms of an earth signal including a noise component according to the present invention.

10 illustrates a signal waveform after filtering according to the present invention.

11 illustrates signal waveforms after waveform modification in accordance with the present invention;

12 illustrates a signal waveform after waveform inversion according to the present invention.

13 shows signal waveforms after waveform comparison according to the invention;

14 is a view showing a polarity discrimination waveform after calculating the average value according to the present invention;

The present invention relates to a ground fault detecting apparatus and a ground fault detecting method thereof in a live state, and more particularly, a ground fault detecting device and a ground fault which can quickly and accurately detect a ground fault while preventing electronic devices from being damaged even in a live state. It is about exploration method.

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 easy for citizens to contact, there is a high risk of a safety accident. Therefore, a short circuit is to be found and repaired immediately if a short circuit is identified.

Conventionally, in order to search for an earth leakage point or an earth leakage section, the low voltage power line is blacked out to isolate the connection point for each section with an insulation resistance meter and to check the insulation resistance by checking the insulation resistance, or to check the magnitude of the leakage current by following the wire path with a leakage ammeter. 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, in the event of a short circuit in the underground cable, it is impossible to find out the location of the short circuit accurately due to invisibility and lack of suitable equipment. Therefore, it is necessary to replace the cable that suspects a short circuit or to repair and repair the suspected short circuit. There was no.

In the event of a short circuit on the underground cable 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 decrease.

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 no power is supplied to the underground line, and the live state refers to a state in which power is being 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 the high voltage DC pulse method was that the wire leak detector could not be designed with high sensitivity to extract a signal detected along with the noise present on the ground. .

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

However, the high voltage DC pulse method may be applied only in a diagonal state, as shown in FIG. 1, when a high voltage of 100 V or more is applied in a state in which a commercial power of AC 220 V 60 Hz is supplied. This is because, as synthesis occurs, the maximum voltage exceeds the 400 V, which is the maximum allowable voltage that the surge protector built into the electronics can withstand, threatening to break the electronics.

Referring to FIG. 2, in 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 to the electronic device is greater, 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 has spurred 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.

In the present invention, to solve the problems of the prior art as described above, to propose a ground fault detecting device in the active state that can detect the ground fault in the live state without affecting the consumer's electronic devices and a ground fault detection method thereof do.

Another object of the present invention is to provide a ground fault detecting apparatus and a ground fault detecting method thereof in an active state capable of accurately detecting a ground fault point.

It is another object of the present invention to provide an earth leakage detecting device in an active state and an earth leakage detecting method thereof in which an earth leakage point can be quickly and accurately detected.

In order to achieve the object as described above, according to a preferred embodiment of the present invention, a method for exploring the leakage of the underground line in the live state between the ground transformer and the customer in a live state, (a) on the ground transformer N phase Applying an asymmetrical AC pulse wave to a connected ground line, wherein the ground transformer outputs a signal having a waveform obtained by combining the asymmetrical AC pulse wave and a commercial power source; (b) receiving a ground signal comprising a signal component having the synthesized waveform from the ground at the exploration point; (c) processing the ground signal and outputting a polarity value at the search point, wherein a short circuit is detected in the live state according to the polarity value; A method is provided.

According to another aspect of the present invention, a device for exploring in a live state the leakage of the underground cable line located between the ground transformer and the customer, a transmitter for applying an asymmetrical AC pulse wave to the ground line connected to the N phase of the ground transformer- The ground transformer outputs a signal having a waveform obtained by combining the asymmetric AC pulse wave and a commercial power supply; A detection device for receiving a ground signal including a signal component having the synthesized waveform from the ground of the detection point, and processing the ground signal to output a polarity value at the detection point, in accordance with the polarity value. An earth leakage detecting device in a live state is provided, characterized in that whether or not an earth leakage is determined at the detection point.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same components have the same number as much as possible even if displayed on different drawings. Hereinafter, a preferred embodiment of the earth leakage detecting apparatus and the earth leakage detecting method thereof in the active state according to the present invention will be described in detail.

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

Referring to FIG. 3, an underground cable path is located between the ground transformer 303 and the customer 306, and the ground transformer 303 changes the voltage or current of an alternating current by using electromagnetic induction. Commercial power (60 Hz, 220 Vac) is supplied to each electronic device 307.

When a short circuit occurs between the sections 303 and 306 of the underground cable line, a ground fault detecting apparatus including a transmitter 301 and a detector 305 is provided to detect a ground fault point.

The transmitting device 301 according to the present invention generates and outputs a pulse wave for detecting an earth leakage point. The detection device 305 receives the earth signal output according to the combined signal of the pulse wave and the commercial power supply, and performs a function to find an earth leakage point by processing it.

According to a preferred embodiment of the present invention, the earth leakage point is made in the live state, the asymmetric AC pulse wave can be used as shown in Figure 3 for the earth leakage detection in the live state.

As described above, the live state is a state in which power is supplied from the ground transformer 303 to the customer side.

On the other hand, in the present invention, 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.

In the present invention, the application of the asymmetric AC pulse wave for the earth leakage detection in the live state is that the noise signal appears symmetrically in the ground signal received from the detection device 305, so if the symmetric AC pulse wave is used, the noise signal This is because the interpretation of the signal becomes impossible due to the synthesis of.

In addition, it is preferable that the asymmetric AC pulse wave according to the present invention have a frequency of 50 V or less and 2 KHz, which is various kinds of electrons connected to the customer 303 even in a live state, that is, even when synthesis with a 60 Hz and 220 Vac commercial power occurs. This is to accurately detect the earth leakage point without damaging the internal circuits of the devices 307, for example, various devices such as a refrigerator, a computer, and a TV.

However, the voltage and frequency of the asymmetric AC pulse wave are for illustration, and are not necessarily limited thereto.

The transmitter 301 according to the present invention applies an asymmetric AC pulse wave signal to a neutral line of the ground transformer 303, that is, a ground line connected on an N (Neutral Line).

Accordingly, as shown in FIG. 6, a synthesized waveform having a maximum peak voltage of −311 V to +361 V is generated on the N phase of the ground transformer 303.

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 50V이하가 되는 경우, 합성 파형의 최대 피크는 340V + 50V = 390V가 되기 때문에 전자기기 내부에 존재하는 보호 회로를 파손시키지 않게 된다. On the other hand, Figure 6 is based on when the ideal commercial power source is applied, in practice, the commercial power source may be 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 50V or less, the maximum peak of the synthesized waveform is 340V + 50V = 390V, so that the protection circuit existing inside the electronic device is not broken.

On the other hand, according to the present invention, even if the earth leakage detection even in the live state, since the return current does not flow to the consumer side as shown in FIG.

According to a preferred embodiment of the present invention, the detection device 305 analyzes the signal input from the ground to find out whether the current leaked out and the exact point of leakage.

Since there are many noise components in the ground signal, the detection device 305 according to the present invention removes the noise components through signal adjustment and filtering.

In addition, the detection device 305 generates an asymmetric AC pulse wave containing a DC component by appropriately processing the signal from which the noise component is removed, and finally determines whether there is a short circuit through the average value of the DC component. do.

In this case, the average value of the DC component is a polarity value at the detection point, and it may be determined that there is a short circuit at the corresponding point when the polarity appears.

4 is a block diagram illustrating a detailed configuration of an earth leakage detecting apparatus according to an exemplary embodiment of the present invention, and FIG. 4 is a diagram illustrating a detailed configuration of the detection apparatus 305 shown in FIG. 3 in the earth leakage detecting apparatus. .

As illustrated in FIG. 4, the earth leakage detecting apparatus according to the present invention includes a ground signal input unit 400, a signal adjusting unit 402, a filter unit 404, an amplifier 406, a signal discriminating unit 408, and a ground voltage. The measurement unit 410 may include a display unit 412 and a sound output unit 414.

The ground signal input unit 400 receives a ground signal including a signal component of the waveform synthesized as described above from the ground at the exploration point.

At this time, the ground signal is input as only a few mV when viewed at a voltage level as shown in FIG. In other words, 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 signal adjusting unit 402 performs a process of adding or subtracting a signal according to the frequency band of the received ground signal, and the filter unit 404 filters the signal adjusted signal as shown in FIG. 10 to exclude noise components. And convert it into the waveform including the signal according to the commercial power.

The filter unit 404 according to the present invention may be a band pass filter (BPF) designed with high sensitivity.

The amplifier 406 amplifies the signal in order to extract a meaningful component from the filtered signal.

The signal discriminating unit 408 processes the amplified signal to determine whether there is a short circuit.

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

As illustrated in FIG. 5, the signal discriminating unit according to the present invention may include a waveform modifying unit 500, a waveform inverting unit 502, a waveform comparing unit 504, and an average value circuit unit 506.

In order to detect a ground fault according to the present invention, a signal according to a commercial power source must be removed. As illustrated in FIG. 11, the waveform modifying unit 500 removes a commercial power component from a signal amplified through waveform modification.

The waveform inversion unit 502 inverts the modified signal as described above, and the waveform comparison unit 504 performs a waveform comparison process on the inverted signal.

The signal after the waveform comparison is an inverted asymmetric AC pulse wave including a DC component. When the signal is inverted again and passed through the average value circuit unit 506, a DC value (polar value) for determining polarity is obtained. Finally output That is, the average value circuit section 506 outputs the polarity discrimination waveform through the average value calculation.

The above polarity represents a potential difference at an exploration 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 506 is output through the display unit 412.

In addition, when it is determined that there is a short circuit, the sound output unit 414 may output an alarm sound.

Meanwhile, according to the present invention, the signal passing through the filter unit 404 may be input to the ground voltage measuring unit 410, and the ground voltage measuring unit 410 measures the ground voltage through the filtered signal to detect the earth leakage. The ground voltage at the point allows for a more accurate determination of leakage.

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.

8 is a flow chart of an earth leakage exploration process in the live state according to the present invention.

8 illustrates a process performed by the detector 305 after applying an asymmetric AC pulse wave from the transmitter 301. Referring to FIG. 8, the ground fault detecting apparatus receives an earth signal (step 800). Signal adjustment is performed to subtract the magnitude of the input ground signal (step 802).

Thereafter, filtering is performed to remove noise components (step 804), and amplification is performed for meaningful signal extraction (step 806).

The amplified signal is subjected to waveform transformation, and thus the commercial power component is removed (step 808).

Thereafter, waveform inversion and waveform comparison are performed (steps 810 to 812). Waveform inversion and waveform comparison result in an asymmetric AC pulse wave including the DC component.

After the waveform comparison process is completed, the signal is inverted and converted into a DC value (polarity value) capable of discriminating polarity through the average value circuit unit 506 (step 814).

Thereafter, the polarity value is output as a numerical value which can be checked by the user through the display unit 412 (step 816).

In operation 812, the signal after waveform comparison may be output to the sound output unit 414, and the sound output unit 414 may output an alarm sound (step 818).

Meanwhile, the ground voltage measurement may be performed on the signal filtered in step 804 (step 820), and the measured ground voltage may be output to the outside (step 822).

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

As described above, according to the present invention, since the low voltage asymmetric AC pulse wave is used, there is an advantage in that a short circuit can be detected in the live state.

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

In addition, according to the present invention, it is possible to prevent the physical and time loss that occurs when replacing the cable to the part where there is no leakage because it finds the leakage point accurately and quickly through the asymmetric AC pulse wave.

Claims (7)

As a method of exploring live leakage of underground cables located between ground transformers and customers, (a) applying an asymmetric AC pulse wave to a ground line connected to N phase of the ground transformer, wherein the ground transformer outputs a signal having a waveform of the asymmetric AC pulse wave and a commercial power supply; (b) receiving a ground signal comprising a signal component having the synthesized waveform from the ground at the exploration point; And (c) processing the ground signal to output a polarity value at the exploration point, The earth leakage detecting method in the live state, characterized in that whether or not the earth leakage at the detection point according to the polarity value. The method of claim 1, And wherein the asymmetric AC pulse wave has a voltage in a range such that the synthesized waveform does not exceed a maximum allowable voltage of an electronic device connected to the consumer side. The method of claim 1, In step (c), A waveform modification step of removing a commercial power component from the amplified signal, A waveform inversion step of inverting the modified waveform; A waveform comparison step of comparing the inverted waveforms; And And a mean value applying step of outputting a DC value corresponding to the polarity by using the compared waveform.  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 a ground line connected to the ground transformer N, wherein the ground transformer outputs a signal having a waveform obtained by combining the asymmetric AC pulse wave and a commercial power source; A detection device for receiving a ground signal including a signal component having the synthesized waveform from the ground of the detection point, and processing the ground signal to output a polarity value at the detection point, The earth leakage detecting device in the live state, characterized in that whether or not the earth leakage at the detection point is determined according to the polarity value. The method of claim 4, wherein And the asymmetric AC pulse wave has a voltage in a range in which the synthesized waveform does not exceed a maximum allowable voltage of an electronic device connected to the consumer side. The method of claim 4, wherein The detection device, A signal adjusting unit which adds or subtracts a signal size of each frequency band included in the ground signal; A filtering unit to filter the adjusted signal; An amplifier for amplifying the filtered signal; And And a signal discrimination unit configured to process the amplified signal and calculate a polarity value. The method of claim 6, The signal determination unit, A waveform modification unit which removes a commercial power component from the amplified signal; A waveform inversion unit for inverting the modified waveform; A waveform comparison unit comparing the inverted waveforms; And And a mean value circuit unit for outputting a DC value corresponding to the polarity by using the compared waveform.

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