CN102288868A - One-point grounding detector and detection method for voltage transformer secondary coil neutral line - Google Patents
One-point grounding detector and detection method for voltage transformer secondary coil neutral line Download PDFInfo
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- CN102288868A CN102288868A CN201110231545XA CN201110231545A CN102288868A CN 102288868 A CN102288868 A CN 102288868A CN 201110231545X A CN201110231545X A CN 201110231545XA CN 201110231545 A CN201110231545 A CN 201110231545A CN 102288868 A CN102288868 A CN 102288868A
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Abstract
The invention discloses a one-point grounding detector and detection method for a voltage transformer secondary coil neutral line. The detector is characterized in that an ammeter and a rheochord are connected between the voltage transformer secondary coil neutral line and an equipotential grounding grid after being connected in series; the resistance value of the rheochord is adjusted, and the corresponding current reading in the ammeter is obtained; a voltmeter is connected between the voltage transformer secondary coil neutral line and the equipotential grounding grid; the variation of the resistance value of the rheochord is detected by the voltmeter; a discharging gap and a disconnecting link are respectively connected between the voltage transformer secondary coil neutral line and the equipotential grounding grid; the overvoltage protection is carried out by the discharging gap; and the disconnecting link controls the on and off of a grounding point in a test. The detector and detection method provided by the invention are suitable for the grounding reliability detection of a voltage transformer secondary loop in the operating, can be used for improving the accuracy rate of a relay protection action in a transformer substation and ensure the safety.
Description
Technical field
The present invention is device and the detection method that the voltage transformer secondary coil neutral line in service (N600) one point earth reliability is detected.
Background technology
Current, transformer substation voltage mutual inductor secondary coil neutral line N600 ground connection reliability in service can't detect, and whether, whether ground connection have multipoint earthing all can not obtain detecting when normally moving.When system's generation earth fault, substation ground network will flow through zero-sequence current, if multipoint earthing is arranged; then can between two earth points, produce pressure reduction; cause the protector measuring magnitude of voltage incorrect, wave form distortion causes the incorrect operation of impedor and directional element.If lose earth point, the distributed capacitance between voltage transformer (VT) first and second coil and the ground capacitance of secondary circuit form dividing potential drop, high tension voltage are introduced secondary circuit, the safety of the critical person and secondary device.
" 18 great anti-accident measures of electrical network of State Grid Corporation of China " relay protection specialty emphasis is implemented to require regulation: the secondary circuit of utility voltage mutual inductor only allows that one point earth is arranged in the pulpit; At the voltage transformer secondary coil of pulpit one point earth, should be at switch yard with the secondary coil neutral point through discharging gap ground connection; Should make regular check on discharging gap, prevent to cause the phenomenon of voltage secondary circuit multipoint earthing.
For satisfying relevant regulations, need a kind of detection method and pick-up unit easily and effectively, be convenient to field personnel's concrete operations and judgement.
Summary of the invention
The present invention is the weak point for avoiding above-mentioned prior art to exist; a kind of voltage transformer secondary coil neutral line one point earth pick-up unit and detection method that is applicable to that voltage transformer secondary in service loop ground connection reliability detects is provided; to improve relay protection action accuracy in the transformer station, guarantee the person and device security.
Technical solution problem of the present invention adopts following technical scheme.
The characteristics of voltage transformer secondary coil neutral line one point earth pick-up unit of the present invention are:
With reometer A be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat after rheochord R connects; Regulate the size of the resistance value of rheochord R, obtain corresponding current indication among the reometer A;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with voltage table V; Detect the variable quantity of the resistance value of rheochord R with described voltage table V;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with discharging gap JB and disconnecting link K, carry out overvoltage protection, control in test opening of earth point with disconnected with described disconnecting link K with described discharging gap JB.
The characteristics of voltage transformer secondary coil neutral line one point earth pick-up unit of the present invention also are:
The range of described voltage table V is 0-10V;
The range of described reometer A is 0-100mA;
The resistance of described rheochord R is 0-10 Ω;
Described discharging gap JB is the 250V type.
The characteristics of the method that voltage transformer secondary coil neutral line one point earth pick-up unit of the present invention detects are:
At first with the disconnecting link closure, remove voltage transformer secondary loop ground wire in the original system, connect test connection, warranty test loop earth point is reliable;
Rheochord R is transferred to 0 Ω, open disconnecting link K, the reading of record reometer A this moment is the reading U1 of T1 and voltage table; Regulate rheochord numerical value, test altogether 5 times, reading Ix and Ux that difference recording ammeter and voltage become, described x is respectively 1,2,3,4,5;
If in process of the test, the reading of reometer does not change, and judges that then voltage transformer secondary coil neutral line N600 loop one point earth is reliable at this moment;
If in process of the test, the reading of reometer changes, and judges that then the voltage transformer secondary coil neutral line N600 loop of this moment has multipoint earthing.
Compared with the prior art, beneficial effect of the present invention is embodied in:
1, the present invention does not influence the operate as normal of voltage transformer (VT) when detecting earth point, can not influence measurement loop, relay protection circuit, personal equipment is not constituted harm.
2, the present invention compares by the electric current that detection and differential pressure loop to the tank capacitance electric current form, and judges the working condition of earth point, and principle is simple, and it is convenient to use.
Description of drawings
Fig. 1 is circuit theory diagrams of the present invention;
Fig. 2 is the capacitance current synoptic diagram;
Fig. 3 causes current diagram for differential pressure;
Embodiment
Referring to Fig. 1, voltage transformer secondary coil neutral line one point earth pick-up unit is set in the present embodiment:
With reometer A be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat after rheochord R connects; Regulate the size of the resistance value of rheochord R, obtain corresponding current indication among the reometer A;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with voltage table V; Detect the variable quantity of the resistance value of rheochord R with described voltage table V;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with discharging gap JB and disconnecting link K, carry out overvoltage protection, control in test opening of earth point with disconnected with described disconnecting link K with described discharging gap JB.
In concrete the enforcement, the range of voltage table V is 0-10V; The range of reometer A is 0-100mA; The resistance of rheochord R is 0-10 Ω; Discharging gap JB is the 250V type.
Test method:
With the disconnecting link closure, remove voltage transformer secondary loop ground wire in the original system earlier, connect test connection, warranty test loop earth point is reliable.Rheochord R is transferred to 0 Ω, open disconnecting link K, the reading of record reometer A this moment is the reading U1 of I1 and voltage table; Regulate rheochord numerical value, test altogether 5 times, reading Ix and Ux that difference recording ammeter and voltage become, x is respectively 1,2,3,4,5.
If in process of the test, the reading of reometer does not change, can judge that voltage transformer secondary coil neutral line N600 loop one point earth is reliable at this moment, only be that the closure with disconnecting link K forms place's ground connection this moment, and judge underproof loop thus and only form one point earth for a place of being removed in the test; Its principle as shown in Figure 2, the test loop does not have earth point, the electric current that flows through reometer all is a secondary line capacitance current over the ground, its size does not change with the change of resistance value, judging does not have other earth point this moment, voltage transformer (VT) is working properly.
If in process of the test, the reading of reometer changes, the voltage transformer secondary coil neutral line N600 loop of then judging this moment has multipoint earthing, in fact be meant, this moment is except the closed place's ground connection that forms of disconnecting link, voltage transformer secondary coil in the test also has other earth point, judges the not only place's ground connection for being removed in the test of underproof voltage transformer secondary coil thus, needs to continue to search other earth point then; Its principle as shown in Figure 3.Owing to also have another earth point in the switch yard, be meant the earth point that another is not removed, the electric current of surveying is the formed electric current of differential pressure Δ U between 2 of switch yard and the experimental stations in test this moment, change loop resistance, according to Ohm law: voltage is constant, and it is big that resistance becomes, and electric current will diminish.Therefore judging the N600 loop exists other earth point.
Claims (3)
1. voltage transformer secondary coil neutral line one point earth pick-up unit is characterized in that:
With reometer A be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat after rheochord R connects; Regulate the size of the resistance value of rheochord R, obtain corresponding current indication among the reometer A;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with voltage table V; Detect the variable quantity of the resistance value of rheochord R with described voltage table V;
Be connected between the voltage transformer secondary coil neutral line and the equipotential earth mat with discharging gap JB and disconnecting link K, carry out overvoltage protection, control in test opening of earth point with disconnected with described disconnecting link K with described discharging gap JB.
2. voltage transformer secondary coil neutral line one point earth pick-up unit according to claim 1 is characterized in that:
The range of described voltage table V is 0-10V;
The range of described reometer A is 0-100mA;
The resistance of described rheochord R is 0-10 Ω;
Described discharging gap JB is the 250V type.
3. method that detects with the described voltage transformer secondary coil of claim 1 neutral line one point earth pick-up unit is characterized in that:
At first with the disconnecting link closure, remove voltage transformer secondary loop ground wire in the original system, connect test connection, warranty test loop earth point is reliable;
Rheochord R is transferred to 0 Ω, open disconnecting link K, the reading of record reometer A this moment is the reading U1 of I1 and voltage table; Regulate rheochord numerical value, test altogether 5 times, reading Ix and Ux that difference recording ammeter and voltage become, described x is respectively 1,2,3,4,5;
If in process of the test, the reading of reometer does not change, and judges that then voltage transformer secondary coil neutral line N600 loop one point earth is reliable at this moment;
If in process of the test, the reading of reometer changes, and judges that then the voltage transformer secondary coil neutral line N600 loop of this moment has multipoint earthing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201110231545XA CN102288868A (en) | 2011-08-12 | 2011-08-12 | One-point grounding detector and detection method for voltage transformer secondary coil neutral line |
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| CN201110231545XA CN102288868A (en) | 2011-08-12 | 2011-08-12 | One-point grounding detector and detection method for voltage transformer secondary coil neutral line |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103605041A (en) * | 2013-11-14 | 2014-02-26 | 国家电网公司 | Non-contact multi-point grounding detection method and system for secondary circuit of current transformer |
| CN104777405A (en) * | 2015-04-30 | 2015-07-15 | 国家电网公司 | Passive voltage transformer secondary circuit N600 multipoint grounding finder and operation method thereof |
| CN105954642A (en) * | 2016-06-08 | 2016-09-21 | 国网山西省电力公司阳泉供电公司 | Portable PT one-point grounding tester |
| CN106054014A (en) * | 2016-07-11 | 2016-10-26 | 国网山东省电力公司聊城供电公司 | N600 one-point grounding test device and application thereof |
| CN107144748A (en) * | 2017-06-02 | 2017-09-08 | 重庆大学 | The Earthing Reliability monitoring method and its system of TT systems based on Injection Signal |
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| CN202177679U (en) * | 2011-08-12 | 2012-03-28 | 安徽省电力公司淮南供电公司 | One-point grounding detection device for secondary coil neutral wire of voltage transformer |
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2011
- 2011-08-12 CN CN201110231545XA patent/CN102288868A/en active Pending
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| CN101038306A (en) * | 2007-04-24 | 2007-09-19 | 华北电力大学 | Device for online monitoring and overcurrent limiting power transformer iron core grounding current |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103605041A (en) * | 2013-11-14 | 2014-02-26 | 国家电网公司 | Non-contact multi-point grounding detection method and system for secondary circuit of current transformer |
| CN103605041B (en) * | 2013-11-14 | 2017-01-18 | 国家电网公司 | Non-contact multi-point grounding detection method and system for secondary circuit of current transformer |
| CN104777405A (en) * | 2015-04-30 | 2015-07-15 | 国家电网公司 | Passive voltage transformer secondary circuit N600 multipoint grounding finder and operation method thereof |
| CN104777405B (en) * | 2015-04-30 | 2018-07-31 | 国家电网公司 | Passive type Secondary Circuit of Potential Transformer N600 multipoint earthing locators and its operation method |
| CN105954642A (en) * | 2016-06-08 | 2016-09-21 | 国网山西省电力公司阳泉供电公司 | Portable PT one-point grounding tester |
| CN106054014A (en) * | 2016-07-11 | 2016-10-26 | 国网山东省电力公司聊城供电公司 | N600 one-point grounding test device and application thereof |
| CN107144748A (en) * | 2017-06-02 | 2017-09-08 | 重庆大学 | The Earthing Reliability monitoring method and its system of TT systems based on Injection Signal |
| CN107144748B (en) * | 2017-06-02 | 2019-09-10 | 重庆大学 | The Earthing Reliability monitoring method and its system of TT system based on Injection Signal |
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Owner name: STATE GRID CORPORATION OF CHINA Effective date: 20121130 |
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Effective date of registration: 20121130 Address after: 232007 No. 18 Chaoyang Middle Road, Anhui, Huainan Applicant after: Huainan Power Supply Company of Anhui Electric Power Co., Ltd. Applicant after: State Grid Corporation of China Address before: 232007 No. 18 Chaoyang Middle Road, Anhui, Huainan Applicant before: Huainan Power Supply Company of Anhui Electric Power Co., Ltd. |
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Application publication date: 20111221 |