US 6,556,397 B2 · Device and method for detecting arc fault

Abstract

A device for detecting arc fault which distinguishes harmful arc from the signal generated by operation of a dimmer and start of electronic devices. Signals outputted from a current transformer is attenuated by a resistor which is coupled in parallel to the current transformer. By the attenuation of the resistor, the signal generated by the operation of a dimmer is not determined to be arc in arc determining part. Harmful arc and the signal generated by the start of the electronic device are distinguished by integrating both signals. As the harmful arc lasts for a long time, large signals are integrated in an integrator while the signal generated by the start of electronic device does not last for a long time.

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Drawings

Claims23

Dependent claims

A device for detecting an arc fault coupled to a conductor, the conductor coupling a source and a load in power distribution system, comprising:

current detecting means which detects variance of current on the conductor and generates a current detection signal proportional to the variance of the current;
signal attenuating means which attenuates the current detection signal to output a first attenuated signal;
signal transforming means for removing noise from the first attenuated signal and limiting the level of the first attenuation signal to a predetermined level to produce a second attenuation signal;
means for determining an arc fault occurrence, which compares the second attenuation signal with a predetermined first reference signal level and generates an arc detection signal if the level of the second attenuation signal is higher than the first reference signal level;
and
means for determining a trip of the conductor which integrates the arc detection signal and generates a trip signal if the integrated arc detection signal level is higher than a predetermined second reference signal level,
wherein said signal transforming means comprises a rectifier, which rectifies the first attenuated signal, a first filter which remove low frequency signal components from an output signal of the rectifier, a level limiter which limits an output signal of the first filter to a predetermined level if the output signal of the first filter exceeds the predetermined level, a buffer which performs buffering of an output signal of the level limiter, and a second filter which remove low frequency signal from an output signal of the buffer.

4 more elements

A method for detecting an arc fault on a conductor which connects a source and a load in a power distribution system, comprising steps of

(a) generating a current detection signal which is proportional to a variance of current flowing on the conductor;
(b) attenuating the current detection signal at a predetermined rate to produce a first attenuated signal;
(c) removing noise from the first attenuated signal in said step (b), and limiting the level of attenuated current detection signal to a predetermined level if the first attenuated signal exceeds the predetermined level, thereby to produce a second attenuated signal;
(d) generating an arc detection signal if the level of the second attenuated signal produced in said step (c) is higher than a predetermined first reference level;
and
(e) integrating the arc detection signal and generating a trip signal if the integrated arc detection signal level is higher than a predetermined second reference level,
wherein, said step (c) comprises the steps of
(i) rectifying the first attenuated signal,
(ii) removing first low frequency signal components from the rectified first attenuated signal,
(iii) limiting the level of the signal of which the low frequency components are removed so that the signal of which low frequency components are removed does not exceed a predetermined level, buffering the signal of which the level is limited;
and
(iv) removing second low frequency signal components from the buffered signal.

9 more elements

Dependencies are inferred from the claim text.

Description7,236 words

Summary2,222 words

#The entire disclosures of applicants' Korean patent application numbers KR 2000-0025385 and KR 2001-0022392 are incorporated herein by reference.

#The present invention relates to a device for detecting an arc fault, more particularly the present invention relates to device for detecting an arc fault, which distinguish effectively the harmful arc causes fire from the signal generated by a dimmer and start of an electronic device.

#Low voltage networks, typically 600 volts and below, are used to distribute electric power in a specified area, such as part of a city, an industrial or a commercial area. Often, the cables in such networks are located underground. Generally, the network is designed to feed at more than one point, and therefore, has multiple sources. Occasionally, the cables fail due to various causes such as thermal degradation, age, moisture or rodent damage. The networks are protected by circuit breakers and in order to isolate the faulty cable and to minimize disruption of the networks, cable limiters are provided at the ends of the cables. Cable limiters are fuse-like devices that only react safely to high voltage and low impedance faults, such as those created by phase-to-phase faults.

Brief description of the drawings30 figures

#FIG. 1 is a schematic diagram illustrating an example of serial arcing in a current carrying conductor,

#FIG. 2 is a schematic diagram illustrating an example of parallel arcing between two current carrying conductors,

#FIG. 3 is a schematic diagram illustrating an example of ground arcing between the current carrying conductor and the ground,

Detailed description4,235 words

#Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

#FIG. 10 illustrates a schematic block diagram of the arc fault detection device according to the preferred embodiment of the present invention.

#As shown in FIG. 10, the arc fault detecting device according to the preferred embodiment of the present invention may include current detecting part 1000, signal transforming part 1002, arc determining part 1004 and trip determining part 1006.

Facts

Application

10/016,683Filed 17 Dec 2001 · continuation in part

Priority

KR 2000-002538512 May 2000

Published

US 2002/0008950 A14 Jul 2002

Granted

29 Apr 2003

Term ended

10 May 2021

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification3 codes

H02H 1/0015
Concerning the detecting means: using arc detectors
H02H 3/04
Details: with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
H02H
Emergency protective circuit arrangements

Family

Application09/852,117Parent of this continuation-in-part · filed 10 May 2001

US 2002/0085327 A1Pre-grant publication · published 4 Jul 2002

US 2002/0008950 A1Published application

US 6,532,139 B2Related patent

US 6,556,397 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

12 May 2000Priority claimedKR 2000-0025385
17 Dec 2001Application filedUS 10/016,683
21 Feb 2002Assigned to Human El-Tech, Inc., Kim, Cheon Younassignment of assignor's interest
4 Jul 2002PublishedUS 2002/0008950 A1
29 Apr 2003GrantedUS 6,556,397 B2
8 Jul 2005Assigned to Seochang Electronic Communication Co., Ltd.assignment of assignor's interest
10 May 2021Term endedEstimated

Device and method for detecting arc fault

Life of this patent

Device and method for detecting arc fault

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims23

Description7,236 words

Drawings

Classification3 codes

Life of this patent

Description7,236 words