KR101454203B1 - Low current arc detecting system - Google Patents

Abstract

The present invention relates to a low-current arc detection system. The low-current arc detection system according to an embodiment of the present invention includes: a zero-crossing unit; a broadband high-frequency current detector; a low-frequency current detector; a leakage current detector; an arc-pulse converter; an air quasi-peak detector; a root mean square (RMS) current calculation unit; an overload detector; a short-circuit determination unit; a control unit; and a relay trip blocking unit. A core including a coil on a toroidal shaped bobbin is wound around the broadband high frequency current detector. The arc pulse converter has a low pass and a filter to convert a filter output signal to a pulse.

Description

[0001] LOW CURRENT ARC DETECTING SYSTEM [0002]

The present invention relates to a low current arc detection system and method for preventing an electric fire from an arc fault occurring in a wiring and an electric device, and more particularly, to a low current arc detection system and a method thereof, The present invention relates to a low current arc detection system capable of preventing an electric fire from being prejudiced through a harmful arc and a harmless arc so as to prevent an arc malfunction trip interruption.

Electric fires are continuously occurring, and electric fires account for about 20% of total fires. In Korea, an earth leakage circuit breaker is installed to prevent electric fire. However, electric fires are constantly occurring even when the earth leakage breaker is installed 100% in general houses.

The earth leakage breaker is a device that cuts off the overcurrent and the leakage current. Although it has a large effect of preventing electric shock, it is insufficient in terms of preventing an electric fire caused by an arc. Therefore, electric fires have not been reduced until now and the amount of damage is increasing.

In 2009, 10,778 electric fires accounted for 22.8% of the total fires, 326 people injured and 58,185 million property damage. In other words, an average of 29 cases occurred daily, causing damage to 11 people and property damage of 159 million won.

In 1994, a joint research study was carried out to identify the causes of electrical fires using NFPA, CPSC, and UL as the major disaster prevention organizations in the United States. According to the report, more than 40% -fault). < / RTI >

In addition, as a result of analyzing the electric fires that occurred for five years from 1994 to 1998, about 73,500 electric fires are generated annually, and about 60,000 (80%) of them are reported as fires due to arc failure.

As a result, in the United States, the installation of an Arc Fault Circuit Interrupter (AFCI) in the power supply circuit of a bedroom load device of a house has been stipulated since 2002. Since 2008, most electric circuits such as a bedroom, a living room, We have strengthened regulations to install breakers. As a result, the electric fire in the house was greatly reduced.

In addition, development and dissemination of electric fire prevention devices are now urgently needed. In 1976, KS4613 in Korea was enacted the facility standard in case of short - circuiting to prevent electric shock. However, since electric fire prevention effect is insufficient, electric fires have been occurring until recently. Therefore, it is time to develop and spread the electric fire prevention system in Korea and create environment.

On the other hand, in relation to the technology for detecting an arc for fire prevention, a large number of registered and disclosed other than Korean Patent Laid-Open No. 10-2007-0005278 (hereinafter referred to as 'precedent document') are disclosed. The above-mentioned prior art discloses a configuration in which an arc is detected and processed according to the difference of the electric current or the voltage difference generated in the electric line of the load in use.

However, in the conventional art including the above-mentioned prior art, arc detection of a broadband high frequency RF band is not properly performed when a serial arc phenomenon of less than 3A occurs, thereby causing an arc malfunction trip.

Korean Patent Publication No. 10-2007-0005278.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is a first object of the present invention to provide a method and apparatus for detecting an arc fault generated at a low current of less than 3A, And to provide a low current arc detection system which can be prevented in advance.

A second object of the present invention is to provide a low current arc detection system capable of detecting an arc at a lower current by detecting an arc in a broadband high frequency RF band.

A third object of the present invention is to provide a low current arc detection system which can prevent arc fault trip interruption by distinguishing harmful arc and harmless arc.

According to an aspect of the present invention, there is provided a low current arc detection system comprising: a zero crossing unit for rectifying commercial AC power to generate a reference signal for counting whether an arc is generated; A CT (Current Transformer) current sensor, comprising: a broadband high frequency current detector for detecting a high frequency (RF) arc current from a commercial AC power source to detect a high frequency arc signal; A CT (Current Transformer) current sensor, comprising: a low frequency current detector for detecting a low frequency current from a commercial AC power source; A zero current transformer (ZCT) current sensor, comprising: a leakage current detector for detecting a current generated when a leakage current flows from a commercial AC power source; An arc pulse converting unit for amplifying the high frequency arc current detected through the wideband high frequency current detecting unit and converting the high frequency arc current into a pulse so that the arc signal can be periodically counted; An arc quasi-peak detector for amplifying the high-frequency arc signal converted by the arc pulse converter and converting the high-frequency arc signal into a quasi-peak signal so as to detect a change pattern and a frequency variation of the high-frequency arc signal; An effective value current calculator for calculating an effective value of the low frequency current detected through the low frequency current detector; An overload detecting unit for detecting a parallel arc, an overcurrent, and a current generated during a short circuit from the current detected through the low frequency current detecting unit; A leakage judging unit for judging whether or not there is a short circuit according to the difference value of the phase current based on the current detected through the leakage current detecting unit; An arc pulse converting unit, an arc quasi-peak detecting unit, an rms value calculating unit, an overload detecting unit, and a short-circuit judging unit to judge an arc detection in a low current region. A controller for determining a short circuit, an overload, and an arc based on the signal input through the unit; And a relay trip interrupter electrically separating a power input portion and a load output portion in the event of a harmful arc, under the control of the control portion; .

Further, the broadband high-frequency current detecting unit is characterized in that a core having a coil is wound on a bobbin having a toroidal shape.

Further, the arc pulse converting unit is constituted by a low-pass filter, and converts the filter output signal into a pulse.

Also, the control unit may check the reference signal generated through the zero crossing unit, the signal converted through the arc pulse converting unit and the arc quasi-peak detecting unit, and count the pulse of the arc signal for each of the wideband frequencies. An arc confirmation module for confirming an arc; An arc generation amount extracting module for extracting an arc generation amount according to time which is a periodic variation amount of an arc signal from a signal converted through the arc quasi-peak value detecting unit; And a harmful arc determination module that compares an effective value calculated through the rms value calculation section with a value counted by frequency as a reference value and compares the arc generation amount extracted through the arc generation amount extraction module with a reference value to determine a harmful arc. And a control unit.

The harmful arc determination module may be configured such that, when the value counted for each frequency through the arc confirmation module is equal to or greater than an effective value calculated through the effective value current calculation unit, and the arc generation amount extracted through the arc generation amount extraction module is equal to or greater than a reference value, And the relay trip interrupter performs the trip operation by judging the arc.

According to the present invention as described above, it is possible to prevent a large amount of electric fires occurring in wiring and electric devices by detecting an arc fault occurring at a low current of less than 3A.

Further, according to the present invention, an arc signal can be detected in a high frequency RF band (100 kHz-1 MHz), so that it is possible to detect more arc signals than existing products and to detect an arc at a lower current.

According to the present invention, not only bimetallic blocking but also digital overcurrent shutoff and short circuit protection can be provided for the overcurrent protection of the conventional circuit breaker.

In summary, there is also an effect that it is possible to prevent an accident such as a series arc (less than 3A) failure which causes an electric fire, a parallel arc fault, an overload protection, a short circuit protection,

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic diagram conceptually illustrating a low current arc detection system in accordance with the present invention. FIG.
2 is a circuit diagram showing an operation state of a low current arc detection system according to the present invention;
3 is a view showing an example of a broadband high-frequency current detector formed of a winding core and a bobbin according to the present invention.
FIG. 4 is a graph illustrating gain characteristics according to a frequency of the broadband high-frequency current detector according to the present invention. FIG.
FIG. 5 is a graph comparing a frequency spectrum of a steady state and an arc in accordance with the present invention. FIG.
FIG. 6 illustrates an example of a commercial AC power arrangement for performing arc detection and relay blocking according to the present invention; FIG.
FIG. 7 is a graph showing a measurement chart showing a low-current cut-off characteristic when an arc is generated according to the present invention. FIG.
8 is an external view of an arc outlet to which a low current arc detection system according to the present invention is applied.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

The low current arc detection system according to the present invention will be described with reference to FIGS. 1 to 8. FIG.

FIG. 1 is a schematic diagram illustrating a low-current arc detection system according to an embodiment of the present invention. FIG. 2 is a circuit diagram illustrating an operation state of the low-current arc detection system according to the present invention.

As shown in the drawing, the zero crossing unit 10, the broadband high frequency current detection unit 20, the low frequency current detection unit 30, the leakage current detection unit 40, the arc pulse conversion unit 50, the arc quasi-peak detection unit 60, An overload detection unit 80, a leakage determination unit 90, a control unit 100, a relay trip interruption unit 110, and an auxiliary power supply unit 120. The actual value current calculation unit 70, the overload detection unit 80,

The zero crossing unit 10 rectifies commercial AC power to generate a reference signal for counting whether or not an arc is generated. At this time, the zero crossing unit 10 is composed of a circuit including a bridge rectifying diode and a photocoupler.

The broadband high frequency current detector 20 is a CT (Current Transformer) current sensor, and detects a high frequency (RF) arc current from a commercial AC power source to detect a high frequency arc signal.

Specifically, the broadband high-frequency current detecting unit 20 is composed of a winding core a and an outer shield bobbin b as shown in Fig. 3, and the core is wound on a bobbin having a toroidal shape. At this time, the core is a non-magnetic material or a magnetic material, and there is no magnetic limitation. In this embodiment, a non-magnetic Rogowski coil having excellent saturation characteristics and excellent frequency characteristics can be used for sensing the variation of the instantaneous current in a wide band.

Since this winding core is made of a coil of several hundred turns, it is very vulnerable to external noise (EMS), and a separate Faraday chip is required to electrically isolate the external noise and the arc signal.

Thus, as shown in FIG. 3 (b), the chaffer bobbin is configured to form a separate shield winding outside the troy-less coil. The turn ratio of the primary winding shield winding is not specified but is made of 1: 1 winding for impedance matching. FIG. 3 (c) shows the current sensor assembly in which the primary winding and the shield winding are assembled, and is configured in a shape filled with epoxy.

FIG. 4 is a graph showing a gain characteristic according to frequency of the broadband high-frequency current detecting unit 20 according to the present invention. When the frequency of an arc signal causing an electric fire is analyzed, a broadband signal of 3 kHz-1 GHz appears.

Therefore, it is extremely difficult to detect an arc signal and to distinguish it without malfunction. Conventional arc breaker products in low frequency band (3kHz-100kHz) have problems in malfunction at home and industrial sites. The harmonics of the power supply current will affect the algorithm to determine whether the arc signal is present.

Therefore, in the present invention, a current sensor having a high amplification gain characteristic in a wide band (100 kHz-1 MHz) region is applied.

FIG. 5 is a graph showing frequency spectra of a steady state and an arc in accordance with the present invention, and is a power supply current frequency spectrum generated during normal operation and arc operation based on a general household electric load device. Respectively. And exhibits the largest arc energy spectrum in the 100 kHz-1 MHz region.

The low frequency current detector 30 is a CT (Current Transformer) current sensor that detects a low frequency (60 Hz) current from a commercial AC power source.

The leakage current detection unit 40 is a ZCT (Zero Current Transformer) current sensor, and detects a current generated when a leakage current flows from a commercial AC power source in order to prevent electric shock or the like.

The arc pulse converting unit 50 amplifies the high frequency arc current detected through the broadband high frequency current detecting unit 20 and converts it into a pulse so as to periodically count the arc signal. At this time, the arc pulse converting unit 50 is constituted by a low-pass filter, and converts the filter output signal into a pulse.

The arc quasi-peak value detecting unit 60 amplifies the high frequency arc signal converted through the arc pulse converting unit 50 and converts it into a quasi-peak value signal so as to detect a change pattern and a frequency variation amount of the high frequency arc signal.

The rms value current calculating unit 70 calculates the rms value of the low frequency current detected through the low frequency current detecting unit 30. [

The overload detecting unit 80 detects a parallel arc, an overcurrent, and a current generated upon short-circuiting from the current detected through the low-frequency current detecting unit 30.

The short-circuit judging section 90 judges whether or not there is a short circuit in accordance with the difference value of the phase current based on the detected current through the short-circuit current detecting section 40.

The control unit 100 includes a zero crossing unit 10, a broadband high frequency current detection unit 20, a low frequency current detection unit 30, a leakage current detection unit 40, an arc pulse conversion unit 40, An overload, an arc, or the like based on the signal input through the input terminal 50, the arc quasi-peak value detector 60, the effective value current calculator 70, the overload detector 80, , An arc confirmation module 101, an arc generation amount extraction module 102 and a harmful arc determination module 103 as shown in FIG.

Specifically, the arc confirmation module 101 checks the reference signal generated through the zero crossing unit 10 and the signal converted through the arc pulse converting unit 50 and the arc quasi-peak detecting unit 60 on a cycle-by-cycle basis , The pulse of the arc signal is counted for each broadband frequency to confirm the arc generation.

On the other hand, determining whether to interrupt the arc only by the count value of the arc signal poses a risk of malfunction. Therefore, in the present invention, the arc quasi-peak value is used to prevent malfunction and to detect a reliable arc signal at a low current.

The arc generation amount extraction module 102 extracts a periodic change amount of an arc signal, that is, an arc generation amount according to time, from the signal converted through the arc quasi-peak value detection unit 60.

The harmful arc determination module 103 compares the effective value calculated through the effective value current calculation unit 70 with a value counted by frequency as a reference value and compares the arc generation amount extracted through the arc generation amount extraction module 102 with a reference value Determine harmful arc.

Specifically, the harmful arc determination module 103 determines whether the value counted for each frequency is equal to or greater than the rms value calculated through the rms value calculation unit 70 and the arc generation amount extracted through the arc generation amount extraction module 102 is equal to or greater than the reference value, It is judged to be a harmful arc so that the relay trip interrupter 110 performs a trip operation. On the other hand, if not, it is determined to be harmless.

At this time, the controller 100 performs complicated algorithms such as overload, short circuit, short circuit, arc occurrence check, hazardous and harmless arc judgment, and the like, and it is not a microcontroller but a digital signal Processor.

The relay trip interrupter 110 electrically separates the power input portion and the load output portion under the control of the controller 100 when a harmful arc occurs.

The auxiliary power supply unit 120 electrically isolates the commercial power supply and the system control power supply, and supplies the system power.

As shown in FIG. 6, the broad-band high-frequency current detector 20, the low-frequency current detector 30, and the leakage current detector 40 ), And a relay trip interrupter 110 can be constituted. At this time, the position of each of the commercial AC power supply line and the neutral line can be changed.

FIG. 7 is a graph showing a measurement chart showing a low current cutoff characteristic at the time of occurrence of an arc according to the present invention. As shown in the figure, when a load current of 1.8 A is generated, the arc is detected to be tripped within 0.2 second when a series arc is generated, which indicates that the arc detection and algorithm according to the present invention operates effectively.

FIG. 8 is an external view showing an arc socket 1 to which a low-current arc detection system according to the present invention is applied, in which a load power inlet 2 for connecting a load to multiple outsides of the case, (3), an arc display unit (4) that allows the user to confirm whether an arc is generated by the external visual system, and the display color can be varied according to the load usage, thereby displaying a user's overload and overcurrent status. And a USB charging port 6 for charging various mobile phones and tablet IT devices.

More specifically, the emotion display unit 5 is displayed in a green state in a steady state, and transmits power consumption to the user according to the amount of brightness. If the emotion display unit 5 is displayed in red, it is judged that the socket outlet current exceeds the rated current of 15 A or more, and indirectly warns the consumer.

As described above, the system has the characteristic advantage of being capable of more accurate arc detection at low currents, thereby solving the problem of unwanted malfunction trip trips.

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that numerous changes and modifications may be made without departing from the invention. Accordingly, all such appropriate modifications and changes, and equivalents thereof, should be regarded as within the scope of the present invention.

10: Zero crossing part
20: Broadband high-frequency current detector
30: Low frequency current detector
40: Leakage current detector
50: arc pulse conversion section
60: an arc quasi-peak value detector
70: Actual value current calculation unit
80: Overload detection unit
90:
100:
110: Relay trip interrupter
120: auxiliary power unit
101: Arc confirmation module
102: arc generation amount extraction module
103: Harmful arc judgment module
1: Arc outlet
2: Load power inlet
3: Load individual switch
4: arc display section
5: Emotion display unit
6: USB charging port

Claims (6)

A zero crossing unit for rectifying commercial AC power to generate a reference signal for counting whether or not an arc is generated;
A CT (Current Transformer) current sensor, comprising: a broadband high frequency current detector for detecting a high frequency (RF) arc current from a commercial AC power source to detect a high frequency arc signal;
A CT (Current Transformer) current sensor, comprising: a low frequency current detector for detecting a low frequency current from a commercial AC power source;
A zero current transformer (ZCT) current sensor, comprising: a leakage current detector for detecting a current generated when a leakage current flows from a commercial AC power source;
An arc pulse converting unit for amplifying the high frequency arc current detected through the wideband high frequency current detecting unit and converting the high frequency arc current into a pulse so that the arc signal can be periodically counted;
An arc quasi-peak detector for amplifying the high-frequency arc signal converted by the arc pulse converter and converting the high-frequency arc signal into a quasi-peak signal so as to detect a change pattern and a frequency variation of the high-frequency arc signal;
An effective value current calculator for calculating an effective value of the low frequency current detected through the low frequency current detector;
An overload detecting unit for detecting a parallel arc, an overcurrent, and a current generated during a short circuit from the current detected through the low frequency current detecting unit;
A leakage judging unit for judging whether or not there is a short circuit according to the difference value of the phase current based on the current detected through the leakage current detecting unit;
An arc pulse converting unit, an arc quasi-peak detecting unit, an rms value calculating unit, an overload detecting unit, and a short-circuit judging unit to judge an arc detection in a low current region. A controller for determining a short circuit, an overload, and an arc based on the signal input through the unit; And
A relay trip interrupter electrically separating a power input portion and a load output portion in the event of a harmful arc under the control of the controller; And a low current arc detection system.
The method according to claim 1,
Wherein the broadband high-
Characterized in that a core having a coil is wound on a bobbin of a toroidal shape.
The method according to claim 1,
Wherein the arc pulse conversion unit comprises:
A low pass filter is configured to convert the filter output signal into a pulse.
The method according to claim 1,
Wherein,
A reference signal generated through the zero crossing unit, a signal converted through an arc pulse converting unit and an arc quasi-peak detecting unit, is checked periodically, and a pulse of an arc signal is counted for each broadband frequency, module;
An arc generation amount extracting module for extracting an arc generation amount according to time which is a periodic variation amount of an arc signal from a signal converted through the arc quasi-peak value detecting unit; And
A harmful arc determining module that compares an effective value calculated through the effective value current calculator with a count value counted by frequency as a reference value and compares the arc generation amount extracted through the arc generation amount extracting module with a reference value to determine a harmful arc; And a low current arc detection system.
5. The method of claim 4,
The harmful arc determination module includes:
When the arcing amount extracted by the arc generation amount extracting module is equal to or greater than the reference value, a value counted by frequency through the arc confirmation module is equal to or greater than an effective value calculated through the rms value calculation unit, To perform a trip operation.
6. An arc socket to which a low current arc detection system according to any one of claims 1 to 5 is applied,
A load power inlet for connecting the load to the outside of the case multiple times;
Load individual switches for individually turning the load electrical devices on and off;
An arc display unit for confirming whether or not an arc is generated by external visual inspection;
An emotion display unit for displaying the overload state and the over current state by allowing the display color to be variable according to the load usage amount; And
A USB charging port for charging various devices; An arc outlet comprising.

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