KR20100072455A - Method for determining by detecting inpulse originated from arc - Google Patents

Abstract

PURPOSE: An arc fault determining method is provided to prevent power source by detecting a specific waveform. CONSTITUTION: An impulse is separated from a conductive line. A detected impulse is amplified. A controller recognizes the amplified impulse. The detected impulse is accumulated during a constant cycle. The size of the voltage of the accumulated impulse is compared with a reference voltage.

Description

Method for determining arc defects using impulse detection {Method for determining by detecting inpulse originated from arc}

The present invention provides a reliable identification method of the characteristic waveforms generated by arc defects in order to prevent electrical fires that may be caused by arc defects in the converter, and when a specific waveform is generated by arc failure, it cuts off the power supply. It is about how to.

The present invention relates to a method for determining an arc defect, and more particularly, to an arc defect detection method for detecting an arc defect caused by damage to insulation in an electrical installation such as an electric wire and a load to prevent an electric fire. It is about.

In general, the use of various electrical protection devices is mandatory for the electrical wiring, and there are circuit breakers or fuses to prevent damages and fires from wiring or equipment due to overload. There is an earth leakage breaker.

Despite the widespread use of electrical protection devices to protect human life and property from electrical disasters caused by the failure of load facilities and tracks, one of the important causes of fires caused by electricity is that various protection devices cannot be prevented. This is due to the presence of electrical faults, the most important of which is the arcing fault.

Most arc faults are not protected by circuit breakers, fuses, or earth leakage breakers because the arc faults may occur in a short time due to short circuits or short circuits caused by sudden damage to the wires. This is because the insulation of the coating is damaged by mechanical damage, connection defects, contamination, etc., and leakage current flows between the wires or between the wires and the ground, and carbonization accumulates and spreads due to the temperature rise of the insulation damage parts. to be.

In addition, arc defects often cause rapid overcurrent or do not directly act on ground. Therefore, it can be detected by the ground protection breaker ELB only when the arc generates a sufficient leakage current through the ground.

Particularly, arc fault is the main cause of fire, but it can be prevented by wiring breaker or earth leakage breaker because it occurs even in the state of low current and high impedance, resulting in loss of life and property by electric fire. (AFCI) is an essential requirement.

In fact, in the United States, NEC regulations require that Arc Defective Circuit Breakers (AFCI) be mandatory in all residential spaces. Some companies are developing in Korea, and several similar products are available.

In the case of the above products, as a method for detecting arc defects, a current transformer (CT), or a current transformer, is generally used.

1 is a diagram showing a shoulder characteristic of a waveform in which an arc defect exists. In general, high frequency noise appears in voltage and current when an arc defect occurs, and in general, due to voltage caused by an arc, compensation for a voltage difference In a circuit without a function, the arc current is lower than the steady state current in the same circuit. The rate of rise of the arc current is generally greater than the rate of rise for the normal current, and in each half cycle, the arc current nearly disappears at zero-crossing and reappears after the zero crossing. The waveform that appears as shown in the zero crossing portion is called a shoulder. In general, the voltage waveform is close to the square wave, and is often sporadically high between the steady currents.

2 is a view illustrating a method of detecting a waveform of a load current by penetrating a conductive line using a current transformer CT or an image current transformer ZCT according to the related art. As shown in the figure, by analyzing the pattern of the load current detected in the conductive line by CT (CT), it is determined whether an arc defect is generated.

In addition, the waveform of the leakage current is detected by the ZCT (Image Current Transformer), or the voltage waveform is detected through the PT (Potential Transformer), and the pattern of the detected waveform is analyzed to determine whether an arc defect is generated.

However, since various load current waveforms, voltage waveforms, and leakage current waveforms are detected in the waveforms detected by the detection device as well as impulses caused by arcs, the presence of arc coupling is analyzed by analyzing the waveforms by the arcs through these detection waveforms. It is not easy to judge the situation.

In order to solve the above problems, an object of the present invention is to provide a method for determining the presence or absence of arc defects by detecting only an instantaneous short period impulse wave or detecting only an instantaneous short period impulse wave.

It is also an object of the present invention to provide a method for detecting only instantaneous impulses caused by an arc using a current transformer or an image current transformer.

It is also an object of the present invention to provide a method for determining the presence or absence of arc defects by sampling a load current and comparing the sampled pattern with a specific pattern unique to the load itself.

It is also an object of the present invention to provide a method of determining the presence of an arc defect by sampling a load current to detect a shoulder, which is a typical feature of a waveform by an arc, in a sampled signal.

According to an aspect of the present invention, there is provided a method of determining an arc defect through a controller by detecting a waveform of a current flowing through a conductive line connected to a load, the method comprising: separating and detecting an impulse from the conductive line; Amplifying the detected impulse and detecting the detected impulse so as to be processed by the controller; Accumulating the detected impulse for a predetermined period; And comparing the magnitude of the accumulated voltage of the impulse with a reference voltage.

The method for detecting an arc defect through a control unit by detecting a waveform of a current flowing in a conductive line, the method comprising: detecting only an impulse in the conductive line; Amplifying the detected impulse and detecting the detected impulse so as to be processed by the controller; Accumulating the detected impulse for a predetermined period; And comparing the magnitude of the accumulated voltage of the impulse with a reference voltage.

Using a current transformer having a hollow portion to detect only an impulse in the conductive line, one conductive line may be overlapped to pass through the hollow portion of the current transformer. In addition, by using an image current transformer having a hollow portion to detect only an impulse in the conductive line, one conductive line may be overlapped with each other to pass through the hollow portion of the image current transformer.

The control unit outputs a trip signal to the circuit breaker when the magnitude of the accumulated voltage of the impulse is greater than or equal to the reference voltage to drive the trip device inside the circuit breaker.

The method may further include detecting and sampling the load current to detect a current waveform; And

And embedding an analysis algorithm for a specific pattern for each type of load in the controller, comparing the sampled current waveform with the specific pattern, and determining whether a specific pattern exists in the sampled current waveform. Can be.

The controller may further include outputting a trip signal to the breaker to drive the trip device inside the breaker when a specific pattern is not present in the sampled current waveform.

The control unit may further include detecting a shoulder that is a characteristic of an arc within the sampled current waveform. When the shoulder is detected, the control unit outputs a trip signal to the breaker to break the circuit breaker. It may be configured to further include; causing the trip device therein to be driven.

Through the method of determining the arc defect by detecting the instantaneous pulse of the present invention, the following effects can be obtained.

First, it detects only impulse wave of short duration by CT, PT, ZCT, or detects only momentary short period of impulse by passing through current transformer by overlapping conductive lines. Impulse has an effect that can determine the presence of arc defects.

Second, the built-in analysis algorithm for the specific pattern of the load is embedded in the controller of the present invention, and compared with the sampled load current waveform, so that arc defects exist through the presence of the specific pattern and the shoulder in the sampled load current waveform. There is an effect that can determine the existence of.

Thirdly, if the accumulated magnitude of the pulse wave detected during a certain period is more than a certain value, in the absence of a specific pattern in the sampled load current waveform, it is determined that an arc defect exists in the presence of a shoulder, thereby tripping the circuit breaker. By driving the device there is an effect that can prevent the electrical fire and the like in advance.

Arc defect determination method using the impulse detection of the present invention will be described in detail below with reference to the accompanying drawings.

3 is a flowchart for detecting an arc defect according to an exemplary embodiment of the present invention, and illustrates a method of determining an arc defect through a control unit by detecting a waveform of a current flowing in a conductive line connected to a load.

First, by separating the pulse voltage from the voltage obtained through the PT from the current flowing through the conductive line, or by separating the pulse current from the current obtained through the CT or ZCT, it is possible to detect the pulse impulse of a short period.

Next, the detected impulse is amplified and detected by the controller so that the controller can recognize and process the accumulated impulse.

The controller generally refers to a concept including a control device or a CPU that calculates, controls, and processes a process according to a set memory such as a microcomputer, MCU, or MPU.

In general, the impulse wave separated from the conductive line may occur not only in the presence of an arc defect, but also in the case of an illuminator, ON / OFF. Such impulse waves are caused by sparks or arcs that appear during normal load operation, and thus it cannot be determined that an arc defect exists. Accordingly, it is necessary to determine that the impulse waveform due to the arc defect is generated only when the voltage of the accumulated pulse is greater than or equal to a certain magnitude while being continuously generated for a predetermined period or more rather than a short period.

To this end, the control unit includes detecting and accumulating the detected pulse signal during a predetermined period in order to receive the detected pulse signal and determine the presence or absence of an arc defect through the pulse.

therefore. When the impulse signal is continuously detected for a predetermined period, the control unit calculates the accumulated voltage of the impulse while accumulating the impulse impulse signal, and determines that the detected pulse is an impulse caused by the arc when the magnitude of the accumulated voltage is greater than or equal to the reference voltage.

In more detail, the constant period sets a period of about 40 to 45 cycles, and if the magnitude of the accumulated impulse voltage is greater than the allowable value of the reference voltage by setting the magnitude of the reference voltage to 0 to 30Vrms during the set period, The detected impulse is determined as an impulse by the arc.

This is a sensitivity problem of the system, and the period or reference voltage to be set may be changed according to the needs of the sensitivity of the arc detection, and such a series of algorithms may be stored and configured in the memory of the controller. The reference voltage may be controlled in various ways.

When the magnitude of the accumulated voltage is greater than or equal to the reference voltage, the controller outputs a trip signal to the circuit breaker so that the trip device inside the circuit breaker is driven. When the circuit breaker trips, it can be configured to transmit a result regarding the occurrence of an arc fault and the operation of the circuit breaker to the user or administrator through wired or wireless communication and to store the transmission result.

As shown in the figure, in addition to the algorithm processing method, the control unit may be configured to compare the reference voltage and the accumulated voltage by using a comparator and output the Vcc as a trip signal when the reference voltage is higher than the reference voltage. It will be driveable.

4 is a state diagram illustrating a method of detecting only an impulse in a conductive line using a current transformer or an image current transformer according to the present invention. As shown in FIG. 4, a conductive line for supplying power to a load, that is, R phase, S phase, and T phase In order to detect only the impulse in the waveform of the current flowing in the conductive line such as the current transformer is installed in the manner shown.

As in the case of Figure 2, the conventional load current waveform detection method allows the conductive line to pass through the hollow part of the current transformer, receives a signal from the current transformer to detect the current waveform, or receives a signal from the current transformer, the waveform of the leakage current To be detected.

A feature of the arc detection method of the present invention is that one conductive line is overlapped so that only an impulse can be detected in the conductive line and configured to pass through the hollow part of the current transformer. In addition, in the case of using the image current transformer, the conductive lines may be overlapped in a batch to pass through the image current transformer.

In the waveform detection method of the conventional load current as in the case of FIG. 2, not only a wave that changes instantaneously, such as an impulse wave by an arc, but also a general AC current waveform in which current changes periodically can be detected by a current transformer or an image current transformer.

Accordingly, since the impulse flowing through the current transformer or the image current transformer cannot detect only the impulse that flows momentarily, as in the conventional method, in order to overcome this problem, the current transformer or the image current transformer is shown in the present invention. It is configured to pass through one conductive line.

That is, in an embodiment such as the present invention, the current is inputted and outputted through the hollow part of the current transformer, and the current waveform inputted into the hollow part of the current transformer and the current waveform outputted again from the hollow part have the same magnitude and have a phase difference of 180 degrees. Since the signals are canceled with each other by the vector sum, only the impulse wave due to the arc that is actually detected is detected.

Therefore, in the method according to the present invention, since the conductive line is configured to input and output current while passing through the hollow portion of the current transformer or the image current transformer, the periodic AC waveform or the image current, etc. is not detected, but the arc in which the current changes suddenly only aperiodically. Only signal by is detected.

5 is a flowchart for detecting an arc defect according to another embodiment of the present invention. The process of determining whether an arc defect is present by comparing the accumulated pulse voltage with a reference voltage by detecting and accumulating a pulse as shown in FIG. Same process as described above.

In this embodiment, in order to determine the existence of a more reliable arc defect, the noise caused by the arc through an algorithm that similarly detects the load current waveform through the current transformer and analyzes the detected current waveform by a fast fourier transform (FFT) method. Configure it to more accurately determine the existence of.

To this end, the controller incorporates an analysis algorithm that analyzes a specific pattern unique to each load in a memory.

In the case of the inherent characteristic pattern of the load, it means a waveform which is repeated in a specific period unique to each load, which can be built in the controller by constructing a database through known data.

Therefore, by sampling the load current, comparing the current waveform of the sampled load and the specific specific pattern of each load built into the controller to determine whether there is a unique specific pattern of the load in the current waveform of the sampled load. Through this, it is possible to exclude the error caused by the impulse detection by the load having the pattern similar to the arc defect and to accurately determine the existence of the arc defect.

When there is no specific pattern unique to the load in the current waveform of the sampled load, it may be determined that there is an impulse noise due to the arc. At this time, the control unit outputs a trip signal to the breaker, so that the trip device inside the breaker Configure to run. When the circuit breaker trips, it can be configured to transmit a result regarding the occurrence of an arc fault and the operation of the circuit breaker to the user or administrator through wired or wireless communication and to store the transmission result.

6 is a flow chart for detecting an arc defect according to another embodiment of the present invention, and further includes detecting a shoulder as shown.

In other words, to detect the load current waveform to determine the presence of the arc defect, the controller further includes detecting a shoulder which is a typical feature of the arc defect.

Similarly, in the controller having an algorithm that analyzes the characteristics of the characteristic patterns of each load, the controller detects the waveform of the load current through sampling and compares it with the inherent characteristic pattern of the built-in load. It will be judged whether or not.

In addition, when the shoulder is detected, the controller outputs a trip signal to the breaker to configure the trip device inside the breaker to be driven. When the circuit breaker trips, it can be configured to transmit a result regarding the occurrence of an arc fault and the operation of the circuit breaker to the user or administrator through wired or wireless communication and to store the transmission result.

7 is a view showing a waveform measured by the embodiment according to the prior art and the present invention the load current in the absence of an arc defect, Figure 8 is a conventional load current in the presence of an arc defect It is a figure which shows the waveform measured by the Example by technique and this invention.

Referring to FIG. 7, the waveform 1 shown in the graph is a waveform measured by a current probe while the arc is not generated, and the waveform 2 is measured by a conventional CT method. Waveform 3 is waveform measured in the manner according to the embodiment of the present invention shown in FIG.

As shown, it can be seen that the current waveform detected by the embodiment of the present invention shown in FIG. 4 has almost no waveform of the load current detected and only white noise of the measuring device is detected.

On the contrary, the load current waveform measured by the current probe or CT shows the difference of detecting the normal AC current waveform as it is.

FIG. 8 shows an arc generation state. In the case of waveform 3, only noise and impulse of the measuring device are detected. This indicates that instantaneous change of current, that is, noise caused by arc, an impulse current, is generated. .

The arrow in the waveform 3 shown at the moment indicates the moment when the noise is generated by the arc, and the shoulder is detected by looking at the marked areas of the waveforms 1 and 2 detected through the current probe and CT.

The two waveforms detected through the CT are sampled and compared with the inherent characteristic patterns of the load by an analysis algorithm built in the control unit, and the presence or absence of an arc defect is determined by the presence or absence of a specific pattern zone and a shoulder of the load.

In other words, the present invention proposes a reliable identification method of features caused by arc defects by improving the method of determining the presence of arc defects by simply analyzing waveform 2 detected through a conventional CT.

In the above detailed description of the present invention, specific embodiments have been described, but the present invention is not limited thereto, and various modifications may be made without departing from the scope of the technical idea of the present invention to those skilled in the art. Will be self explanatory.

1 is a diagram showing a shoulder characteristically present in a waveform in which an arc defect exists.

2 is a diagram illustrating a method of detecting a waveform or a leakage current of a load current by penetrating a conductive line using a current transformer or an image current transformer according to the related art.

3 is a flowchart for detecting an arc defect according to an embodiment of the present invention.

4 is a state diagram illustrating a method of detecting only an impulse in a conductive line using a current transformer or an image current transformer according to the present invention.

5 and 6 are flowcharts for detecting arc defects according to another embodiment of the present invention.

7 is a view showing a waveform measured in the embodiment according to the prior art and the present invention the load current in the state in the absence of an arc defect.

8 is a view showing a waveform measured in the embodiment according to the prior art and the present invention the load current in the presence of an arc defect.

Claims (9)

In the method for detecting the arc of the current flowing through the conductive line connected to the load to determine the arc defect through the control unit, Detecting an impulse separated from the conductive line; Amplifying the detected impulse and detecting the detected impulse so as to be processed by the controller; Accumulating the detected impulse for a predetermined period; And Comparing the magnitude of the accumulated voltage of the impulse and the reference voltage; Arc defect determination method using the detection of the impulse comprising a. In the method for detecting the arc of the current flowing through the conductive line connected to the load to determine the arc defect through the control unit, Detecting only an impulse in the conductive line; Amplifying the detected impulse and detecting the detected impulse so as to be processed by the controller; Accumulating the detected impulse for a predetermined period; And Comparing the magnitude of the accumulated voltage of the impulse and the reference voltage; Arc defect determination method using an impulse detection comprising a. 3. The method of claim 2, Using a current transformer formed with a hollow portion to detect only the impulse in the conductive line, one conductive line is overlapped and configured to pass through the hollow portion of the current transformer, the arc defect determination method using the impulse detection. 3. The method of claim 2, The method for determining arc defects using impulse detection, characterized in that the conductive lines are overlapped with each other so as to detect only the impulse in the conductive line, and the conductive lines overlap each other and pass through the hollow portion of the image current transformer. The method according to any one of claims 1 to 4, The control unit outputs a trip signal to the circuit breaker when the magnitude of the accumulated voltage of the impulse is greater than or equal to the reference voltage to drive the trip device inside the circuit breaker. Judgment method. The method according to claim 1 or 2, Detecting and sampling the load current to detect a current waveform; And And embedding an analysis algorithm for a specific pattern for each type of load in the controller, comparing the sampled current waveform with the specific pattern, and determining whether a specific pattern exists in the sampled current waveform. Arc defect determination method using an impulse detection characterized in that. The method of claim 6, If the specific pattern is not present in the sampled current waveform, the control unit outputs a trip signal to the breaker to drive the trip device inside the breaker; arc fault determination using the impulse detection, characterized in that it further comprises Way. The method of claim 6, And the control unit detects a shoulder, which is a characteristic of an arc, in the sampled current waveform. The method of claim 8, And outputting a trip signal to the circuit breaker to drive a trip device inside the circuit breaker when the shoulder is detected.

Images