CN1335510A - Fault-line selecting method and device for small-current earthing system - Google Patents
Fault-line selecting method and device for small-current earthing system Download PDFInfo
- Publication number
- CN1335510A CN1335510A CN 01118471 CN01118471A CN1335510A CN 1335510 A CN1335510 A CN 1335510A CN 01118471 CN01118471 CN 01118471 CN 01118471 A CN01118471 A CN 01118471A CN 1335510 A CN1335510 A CN 1335510A
- Authority
- CN
- China
- Prior art keywords
- current
- circuit
- traveling wave
- line
- fault
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Landscapes
- Locating Faults (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
The present invention belongs to the field of electric power system. The method is to detect and record the current traveling wave of the loops connected to the same bus to find out the fault line, which has maximum current traveling wave and reverse polarity to the others. The device of the present invention includes: converter, data collector circuit, CPU, result outputting interface circuit, display circuit and power supply inserted successively on one identical circuit board. The present invention can select fault line accurately and may be used in selecting earthing fault in small current earthing system or single-phase large current earthing system.
Description
The invention belongs to field of power, particularly the singlephase earth fault circuit of small current neutral grounding system is selected technology and device in the electric system.
During small current neutral grounding system generation singlephase earth fault, because the not direct ground connection of neutral point, so, can not form short-circuit loop, therefore there is not short-circuit current, have only the little capacitance current of numerical value to flow to the trouble spot.This is an objective phenomenon.
Although do not form short-circuit loop, the fault ground electric current is also little,, this situation can not long-term existence.Non-fault phase voltage can raise on the one hand, and line insulation is threatened; The flame current of earth point can burn out circuit on the other hand, causes the circuit permanent damages.So China Power operating standard regulation: the single-phase earthing duration must not surpass 2 hours, and faulty line must withdraw from from electrical network.Therefore, being this problem of ground path with regard to having proposed that circuit---fault wire is selected problem.
Around this problem, various countries have carried out countless research, have also developed many method and apparatus.For example use the fault-line selecting method of zero sequence power current.Because power frequency zero-sequence current numerical value is very little, the uneven zero-sequence current when being difficult to normal operation is distinguished mutually, so can't correctly select fault wire.Its root problem is to have used the power frequency electric parameters.Cause not having up to now a kind of method or device fundamentally to solve the low current grounding circuit and select problem.
The objective of the invention is to propose a kind of low current neutral grounding system fault route selecting method and device thereof, adopt the transient state travelling wave electric current that is produced after the fault to select fault wire for overcoming the weak point of prior art.Can fundamentally solve low current neutral grounding system fault line options problem.
A kind of low current neutral grounding system fault route selecting method that the present invention proposes, it is characterized in that, detection and record are connected to the current traveling wave on each the loop line road on the identical bus, and wherein current traveling wave numerical value maximum, polarity and other line current polarity of traveling wave opposite are exactly faulty line.
When if said circuit is three-phase line, then the capable ripple of phase current of each circuit and the capable ripple of phase current of corresponding line are compared, perhaps adopt the modulus current traveling wave to compare, wherein current traveling wave numerical value maximum, polarity and other circuit are corresponding mutually or mould current traveling wave polarity opposite, are exactly faulty line.
Above-mentioned detection method is: make Current Transformer change the big electrorheological in the circuit into 1 or 5 ampere little electric current, by current-to-voltage converter this little current signal is transformed into the small voltage signal again, carry out record.
The principle of method foundation of the present invention:
The inventor confirms first by emulation experiment and actual tests: during small current neutral grounding system generation singlephase earth fault, under the effect of trouble spot additional supply, with the capable ripple of voltage and current that produces to the substation bus bar motion.Whether ground connection is irrelevant for capable ripple that this is initial and neutral point, and it is an outwardness.
The current traveling wave that comes from the trouble spot moves to substation bus bar through faulty line, at the bus place catadioptric will take place.Owing to generally be connected to many turnover circuits on the power distribution network bus, so the row wave reflection is very strong.Wherein, the capable ripple on the faulty line is the strongest: it be come from the trouble spot initial reverse row ripple and the reflection after changed direction the ripple that moves ahead and.And the capable ripple on other circuit is to come from the capable wave refraction component on trouble spot and the faulty line and this component is only arranged.So numerical value is very little, polarity and faulty line are opposite.
The present invention proposes to realize the device of said method, it is characterized in that, is plugged on interface circuit, display circuit and power supply that transducer, data acquisition circuit, central processing unit, result on the circuit substrate export successively; Said transducer will come from the loop to be measured 1 ampere or 5 Ampere currents and be transformed into the small voltage signal, said data acquisition circuit is converted into digital signal to this little analog voltage signal, and is stored in the data-carrier store of this data acquisition circuit; Said central processing unit carries out Filtering Processing with the transient current travelling waves data that collect, and result of calculation, and the result after this interface circuit will be handled exports, and shows by display circuit.
Device main performance index of the present invention is as follows:
1, can monitor ten times distribution lines (can write down 30 analog quantity current traveling waves) simultaneously;
2, can select faulty line in real time, take place from earth fault, be selected to faulty line, the time is no more than 100 milliseconds;
The present invention can accurately select fault wire, and it can be applied to:
1. isolated neutral system singlephase earth fault line;
2. neutral by arc extinction coil grounding system single-phase earth fault route selecting;
3. neutral point is through the high resistance grounding system single-phase earth fault route selecting;
Neutral point through in resistance eutral grounding fault single-phase grounding selecting;
5. neutral point is through the route selection of the low resistance earthing system failure;
6. the route selection of neutral-point solid ground (heavy current grounding system) system failure.
Brief Description Of Drawings:
Fig. 1 utilizes the low-current ground fault line selection principle key diagram of current traveling wave for the present invention.
Fig. 2 is a low-current ground fault line selection device embodiment overall construction drawing of the present invention.
Fig. 3 is the data acquisition board circuit structure diagram of present embodiment.
Fig. 4 is the central processing unit plate circuit structure diagram of present embodiment.
The present invention proposes a kind of low-current ground fault line selection method and device embodiment is described in detail as follows in conjunction with each accompanying drawing:
The main points of this method are: the transient current travelling waves that is produced when utilizing earth fault to take place is selected fault wire.Wherein, in the distribution line on being connected to same transformer station, distribution substation bus, if earth fault takes place.So:
(1) the initial transient current travelling waves numerical value maximum that is occurred on the faulty line, the transient state travelling wave current values of other non-ground path is very little;
(2) polarity of faulty line current traveling wave and non-fault line are opposite;
(3) the current traveling wave polarity of non-fault line is identical.
This method is described as follows in conjunction with Fig. 1:
Current traveling wave (the i that comes from the trouble spot
1 instead goes) move to substation bus bar through faulty line, catadioptric (i will take place at the bus place
1 moves ahead).Owing to generally be connected to many turnover circuits on the power distribution network bus, so the row wave reflection is very strong.
Wherein, the capable ripple on the faulty line is the strongest: it is the initial reverse row ripple (i that comes from the trouble spot
1 instead goes) and reflection
After changed the ripple (i that moves ahead of direction
1 moves ahead) and.
I1=i
1 instead goes+ i
1 moves ahead
And the capable ripple on other circuit is the capable wave refraction component (i that comes from trouble spot and the faulty line
2, i
3, i
1), and this component is only arranged.So numerical value is very little, polarity and faulty line are opposite.
i
1And i
2, i
3, i
4Polarity is opposite
i
1Greater than i
2, i
3, i
4
According to this feature, the method for failure line selection is:
Write down the current traveling wave on every loop line road, wherein numerical value maximum, polarity and other line current polarity of traveling wave opposite are exactly faulty line.
In actual three-phase line, the phase current of each circuit should compare with the phase current of corresponding line.
Therefore this method can simplified summary be:
(1) the initial transient current travelling waves numerical value maximum that is occurred on the faulty line, the transient state travelling wave current values of other non-ground path is very little;
(2) polarity of faulty line current traveling wave and non-fault line are opposite;
(3) the current traveling wave polarity of non-fault line is identical.
According to the embodiment of a kind of low current neutral grounding system fault route selecting device of said method design as shown in Figure 2.Comprise a cabinet, interface board 24 and power panel 25 that one circuit substrate is plugged with converter plate 21, data acquisition board 22, central processing unit plate 23, result's output successively are set in this cabinet, hummer 26 and LCD screen 27 are housed in the front of cabinet, are separately installed with power supply jack 28 and incoming line 29 at the side and the back side of cabinet.
The composition and the function of above-mentioned each circuit board are described in detail as follows:
1. converter plate: its is coming from the voltage signal that 1 ampere of the current transformer that is connected on the loop to be measured or 5 Ampere currents are transformed into 5 volts, use for data acquisition, have ten loops, conversion 30 tunnel, there is three-phase current in each loop, and present embodiment adopts common current-to-voltage converter.
2. data acquisition board: it is converted into digital signal to this analog current signal of 5 volts, and is stored in the data-carrier store;
This plank is made up of earth fault hardware-initiated unit mouth and data acquisition unit mouth two parts, as shown in Figure 3.Wherein:
Hardware-initiated unit I is an input current and a threshold value (definite value) relatively, if when the high frequency transient component in the input current reaches threshold value, and the comparer output low level.Judgement ground connection has been taken place.
Hardware-initiated unit I is made up of a bandwidth-limited circuit (the bandpass filter frequency is the 3-10 KHz) and comparer chip (LM293).
Data acquisition unit II is made up of 8 multicircuit switches, 8 high-speed AD converter chips, data-carrier store and correspondent control circuits.(analog to digital conversion) 30 tunnel current data are ceaselessly gathered in the high-speed AD converter circulation, and store in the data-carrier store.
The AD803 that 8 analog to digital converter chips of present embodiment adopt AD company to produce, the AD9300 that 8 multi-way switchs (each multi-way switch is connected four tunnel simulating signal timesharing to 8 AD) adopt the said firm to produce.The loop-around data storer adopts dual port RAM.
3. central processing unit plate: it carries out Filtering Processing to the transient current travelling waves data that data acquisition board collects, and then selects fault wire according to aforesaid selection method.
The composition of this plank is made up of digital signal processor and correspondent peripheral circuit as shown in Figure 4.The amplitude of its main combine digital filtering-wavelet transformation, phase-model transformation and 10 circuits (20 modulus electric currents) and polarity are relatively.
The digital signal processor of present embodiment adopts the TMS320C32 DSP chip of TI company.Among the figure, RAM is a data-carrier store, and Flash is a program storage.Expression such as 16D, 32D is 16 or 32 s' data bus or a program bus
4. output interface plate as a result: this plank shows the result of central processing unit result of calculation (digital quantity) output, and notifies the operator on duty by hummer by LCD screen.
5. power supply: the working power that package unit is provided.
The course of work of present embodiment:
If one single-phase earthing has taken place circuit, this device will start work, and its course of work is as follows:
1, by being installed on the current transformer of (totally ten times) on every circuit, the three-phase current of every circuit (amounting to 30) is introduced into converter plate;
2, each transducer electrorheological about 5 amperes (or 1 amperes) coming from current transformer changes 5 volts voltage signal into;
3, the start unit of high-speed data acquisition plate front will detect the disturbance generation, hardware-initiated unit starting, output triggering level;
4, the data acquisition in the high-speed data acquisition unit is continuous round-robin, if hardware-initiated element starts, then reads 200 sampled points of every circuit three-phase current data from cyclic store;
5, to these 30 independently 200 point data carry out digital filtering and handle;
6, they are carried out phase-model transformation, above-mentioned three-phase electricity flow valuve (A phase, B phase, C phase) is transformed into three modulus electric currents (α modulus, β modulus, 0 modulus);
7, according to every circuit correspondence two line moulds (α modulus and β modulus), the zero sequence modulus is not relatively selected faulty line.
8, selection result (digital quantity, 0 representative is not a fault wire, 1 represents fault wire) is outputed to the result and exports plate as a result.
9, output board will provide the hummer cry as a result, notify the operator on duty, and selection result will be presented on the LCD screen.
Claims (4)
1, a kind of low current neutral grounding system fault route selecting method is characterized in that, detection and record are connected to the current traveling wave on each the loop line road on the identical bus, and wherein current traveling wave numerical value maximum, polarity and other line current polarity of traveling wave opposite are exactly faulty line.
2, low current neutral grounding system fault route selecting method as claimed in claim 1, it is characterized in that, said circuit is a three-phase line, the capable ripple of phase current of each circuit and the capable ripple of phase current or the modulus current traveling wave of corresponding line are compared, wherein current traveling wave numerical value maximum, polarity and other circuit are corresponding mutually or mould current traveling wave polarity opposite, are exactly faulty line.
3, low current neutral grounding system fault route selecting method as claimed in claim 1, it is characterized in that, said detection method is: make Current Transformer the big electrorheological in the circuit be changed into 1 or 5 ampere little electric current, by current-to-voltage converter this little current signal is transformed into the small voltage signal again, carries out record.
4, a kind of device of realizing the method for stating as claim 1 is characterized in that, comprises interface circuit, display circuit and the power supply of the transducer that is plugged on successively on the circuit substrate, data acquisition circuit, central processing unit, result's output; Said transducer will come from the loop to be measured 1 ampere or 5 Ampere currents and be transformed into the small voltage signal, said data acquisition circuit is converted into digital signal to this little analog voltage signal, and is stored in the data-carrier store of this data acquisition circuit; Said central processing unit carries out Filtering Processing with the transient current travelling waves data that collect, and result of calculation, and the result after this interface circuit will be handled exports, and shows by display circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB01118471XA CN1155833C (en) | 2001-06-01 | 2001-06-01 | Fault-line selecting method and device for small-current earthing system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB01118471XA CN1155833C (en) | 2001-06-01 | 2001-06-01 | Fault-line selecting method and device for small-current earthing system |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2003101173599A Division CN1508554A (en) | 2001-06-01 | 2001-06-01 | Single-phase earthing failure line-selecting method for small-current earthing system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1335510A true CN1335510A (en) | 2002-02-13 |
| CN1155833C CN1155833C (en) | 2004-06-30 |
Family
ID=4663212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB01118471XA Expired - Lifetime CN1155833C (en) | 2001-06-01 | 2001-06-01 | Fault-line selecting method and device for small-current earthing system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1155833C (en) |
Cited By (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1309137C (en) * | 2003-07-24 | 2007-04-04 | 上海交通大学 | Method for earthing and line selecting by using compensating electrified wire netting increment function |
| CN1322331C (en) * | 2004-06-07 | 2007-06-20 | 山东大学 | Single-phase grounding selection for small-current system |
| CN100461570C (en) * | 2007-04-13 | 2009-02-11 | 清华大学 | Digital current synthesizer |
| CN101022216B (en) * | 2007-02-07 | 2010-04-07 | 燕山大学 | Small earthing current electric network single phase fault wire selecting method and apparatus |
| CN101814731A (en) * | 2010-04-15 | 2010-08-25 | 中国石油大学(华东) | Distribution network fault line selection method using non-power frequency transient state component |
| CN101533060B (en) * | 2009-04-03 | 2011-03-30 | 清华大学 | Power system fault pre-alarming method based on traveling wave electric amount measurement |
| CN102157981A (en) * | 2011-02-28 | 2011-08-17 | 清华大学 | High-speed data acquisition and digital signal processing device |
| CN101719662B (en) * | 2009-11-06 | 2012-08-08 | 北京衡天北斗科技有限公司 | Fault line selection device for distribution line of small-current grounding system |
| CN102759682A (en) * | 2012-08-02 | 2012-10-31 | 河南易安能源科技有限公司 | Judgment method of small current system one-phase ground circuit and one-phase ground indicator |
| CN102830327A (en) * | 2012-06-15 | 2012-12-19 | 湖南湘能智能电器股份有限公司 | Judging method and device of single-phase grounding fault line of small-current grounding system |
| CN102866327A (en) * | 2012-09-13 | 2013-01-09 | 山西省电力公司大同供电分公司 | Small-current grounding system fault transient traveling wave detection device and method |
| CN103439633A (en) * | 2013-08-28 | 2013-12-11 | 徐州润泽电气有限公司 | Low-current ground fault line selection device |
| CN103558488A (en) * | 2013-08-16 | 2014-02-05 | 国家电网公司 | High impedance grounding fault detection device based on transient state travelling waves |
| CN103840556A (en) * | 2014-03-25 | 2014-06-04 | 清华大学 | Method for sharing multi-interval transient traveling wave signals of intelligent substation in real time |
| CN104316833A (en) * | 2014-10-14 | 2015-01-28 | 广东电网有限责任公司电力科学研究院 | Line selection method for medium-voltage power distribution network fault traveling wave |
| CN105606944A (en) * | 2015-12-18 | 2016-05-25 | 清华大学 | Single-phase grounding fault line selection method and device for distribution system |
| CN109061376A (en) * | 2018-09-19 | 2018-12-21 | 上海蓝瑞电气有限公司 | A kind of judgment method of Small Electric Current Earthing And Routing Device CT incorrect polarity |
| CN110514950A (en) * | 2019-10-13 | 2019-11-29 | 国网山东省电力公司莱芜供电公司 | A kind of neutral by arc extinction coil grounding electric network single-phase earth fault selection method, equipment and readable storage medium storing program for executing |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101533062B (en) * | 2009-04-03 | 2011-01-12 | 清华大学 | Power cable on-line insulated monitoring method based on traveling wave electric amount measurement |
-
2001
- 2001-06-01 CN CNB01118471XA patent/CN1155833C/en not_active Expired - Lifetime
Cited By (21)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1309137C (en) * | 2003-07-24 | 2007-04-04 | 上海交通大学 | Method for earthing and line selecting by using compensating electrified wire netting increment function |
| CN1322331C (en) * | 2004-06-07 | 2007-06-20 | 山东大学 | Single-phase grounding selection for small-current system |
| CN101022216B (en) * | 2007-02-07 | 2010-04-07 | 燕山大学 | Small earthing current electric network single phase fault wire selecting method and apparatus |
| CN100461570C (en) * | 2007-04-13 | 2009-02-11 | 清华大学 | Digital current synthesizer |
| CN101533060B (en) * | 2009-04-03 | 2011-03-30 | 清华大学 | Power system fault pre-alarming method based on traveling wave electric amount measurement |
| CN101719662B (en) * | 2009-11-06 | 2012-08-08 | 北京衡天北斗科技有限公司 | Fault line selection device for distribution line of small-current grounding system |
| CN101814731A (en) * | 2010-04-15 | 2010-08-25 | 中国石油大学(华东) | Distribution network fault line selection method using non-power frequency transient state component |
| CN102157981A (en) * | 2011-02-28 | 2011-08-17 | 清华大学 | High-speed data acquisition and digital signal processing device |
| CN102830327A (en) * | 2012-06-15 | 2012-12-19 | 湖南湘能智能电器股份有限公司 | Judging method and device of single-phase grounding fault line of small-current grounding system |
| CN102759682A (en) * | 2012-08-02 | 2012-10-31 | 河南易安能源科技有限公司 | Judgment method of small current system one-phase ground circuit and one-phase ground indicator |
| CN102866327A (en) * | 2012-09-13 | 2013-01-09 | 山西省电力公司大同供电分公司 | Small-current grounding system fault transient traveling wave detection device and method |
| CN102866327B (en) * | 2012-09-13 | 2015-07-22 | 山西省电力公司大同供电分公司 | Small-current grounding system fault transient traveling wave detection device and method |
| CN103558488A (en) * | 2013-08-16 | 2014-02-05 | 国家电网公司 | High impedance grounding fault detection device based on transient state travelling waves |
| CN103439633A (en) * | 2013-08-28 | 2013-12-11 | 徐州润泽电气有限公司 | Low-current ground fault line selection device |
| CN103840556A (en) * | 2014-03-25 | 2014-06-04 | 清华大学 | Method for sharing multi-interval transient traveling wave signals of intelligent substation in real time |
| CN103840556B (en) * | 2014-03-25 | 2015-10-28 | 清华大学 | Intelligent substation multi-compartment transient state travelling wave signal Real-Time Sharing method |
| CN104316833A (en) * | 2014-10-14 | 2015-01-28 | 广东电网有限责任公司电力科学研究院 | Line selection method for medium-voltage power distribution network fault traveling wave |
| CN105606944A (en) * | 2015-12-18 | 2016-05-25 | 清华大学 | Single-phase grounding fault line selection method and device for distribution system |
| CN105606944B (en) * | 2015-12-18 | 2018-08-28 | 清华大学 | The fault line selection method for single-phase-to-ground fault and device of distribution system |
| CN109061376A (en) * | 2018-09-19 | 2018-12-21 | 上海蓝瑞电气有限公司 | A kind of judgment method of Small Electric Current Earthing And Routing Device CT incorrect polarity |
| CN110514950A (en) * | 2019-10-13 | 2019-11-29 | 国网山东省电力公司莱芜供电公司 | A kind of neutral by arc extinction coil grounding electric network single-phase earth fault selection method, equipment and readable storage medium storing program for executing |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1155833C (en) | 2004-06-30 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN1155833C (en) | Fault-line selecting method and device for small-current earthing system | |
| CN1180272C (en) | Small-current earth fault switch-selecting and sectioning method for power system | |
| CN1804649A (en) | Fault line selection method for single-phase-to-ground fault in small ground current distribution network | |
| CN201532430U (en) | Distribution circuit fault route selecting apparatus for arc-suppression coil grounding system through neutral points | |
| Tian et al. | 400 V/1000 kVA hybrid automatic transfer switch | |
| CN1800867A (en) | Fault line selection method for single-phase-to-ground fault in middle and low voltage distribution network | |
| CN109617026B (en) | Ultrahigh-speed protection method for earth fault of direct-current power grid converter station | |
| CN101188386A (en) | PWM current rectifying system based on DSP and CPLD | |
| CN101976943B (en) | High-power discharge switch gear based on electricity triggered thyristors | |
| Liu et al. | DC side line-to-line fault analysis of VSC-HVDC and DC-fault-clearing methods | |
| CN110739839A (en) | charging method for extra-high voltage flexible direct current full-bridge half-bridge hybrid converter | |
| CN1508554A (en) | Single-phase earthing failure line-selecting method for small-current earthing system | |
| CN1614435A (en) | Circuit fault directional detecting and protecting method for power supply system | |
| CN2729740Y (en) | Apparatus for detecting grounding fault of electric distribution network | |
| CN202978426U (en) | Fault detection terminal based on power distribution automation | |
| CN112003252B (en) | Circuit fault cutting device and direct current system | |
| Liang et al. | Single-Phase ground fault traveling wave line selection method and line selection device field test | |
| CN201685724U (en) | Novel ground overcurrent phase-split control device | |
| CN100365899C (en) | High roltage circuit high resistance grounding protective method | |
| CN104786873A (en) | Voltage reconstruction method based on phase-locked loop | |
| CN212723172U (en) | Synchronous transient recording-type high-current pulse line selection and fault processing device | |
| CN101299543B (en) | Solar controller | |
| CN112255541A (en) | Multifunctional power supply processing device for experiment and connector experiment detection device | |
| CN2594804Y (en) | Cable checking instrument | |
| CN203674683U (en) | Vacuum breaker |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C06 | Publication | ||
| PB01 | Publication | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20040630 |