CN101303375A - Method for detecting high voltage grounding small current - Google Patents
Method for detecting high voltage grounding small current Download PDFInfo
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- CN101303375A CN101303375A CNA2008100168914A CN200810016891A CN101303375A CN 101303375 A CN101303375 A CN 101303375A CN A2008100168914 A CNA2008100168914 A CN A2008100168914A CN 200810016891 A CN200810016891 A CN 200810016891A CN 101303375 A CN101303375 A CN 101303375A
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Abstract
The invention discloses a detection method, in particular to a method for detecting high voltage grounding low current. The method for detecting high voltage grounding low current is characterized by including the steps that: (1) a zero sequence current transformer is arranged at a three-phase conductor, and a resistor is connected between the secondary head and tail of the zero sequence current transformer and the two ends of the resistor are connected with a voltage measuring instrument in parallel; (2) the voltage measuring instrument measures the secondary voltage of the current transformer, and a primary current value is determined by utilizing the secondary induced voltage value of the current transformer, and the primary current and the secondary induced voltage are in direct proportional relation. The method of the invention adopts the special performance of the direct proportional relation between the primary current and the secondary induced voltage and measures the primary current by measuring the secondary voltage of the current transformer and has the advantages of high measuring precision and simple measuring method.
Description
(1) technical field
The present invention relates to a kind of detection method, particularly a kind of method for detecting high voltage grounding small current.
(2) background technology
China's 10KV high-tension line is isolated neutral or through arc suppression coil earthing system, when single-phase earthing took place, ground current was very little, has only several the peace to tens peaces, not enough sometimes 1A.The high-voltage earthing electric current can't directly be used instrument measurement, must measure indirectly by current transformer.The method that detects ground current at present has two kinds: a kind of is to utilize zero sequence current mutual inductor, and the high pressure three-phase conductor is inserted in the zero sequence current mutual inductor.Three characteristics of the middle term conductor phase spacing is big (except the cable power transmission), three-phase centre distance (switch inside) is all in 400 millimeter, cause the zero sequence current mutual inductor volume bigger, magnetic circuit is longer, adding Primary Conductor is a circle punching, the mutual inductor capacity reduces, and measuring accuracy is relatively poor, can not satisfy measurement requirement.Because of leakage field is bigger, load current magnetic field is also big to the interference of zero-sequence current, makes measuring accuracy poorer again.Another kind of measuring method is to measure zero-sequence current after utilizing the parallel connection of threephase current transformer secondary initial and end.Higher to the threephase current transformer accuracy requirement, its no-load voltage ratio must satisfy the requirement of load current.Because of load current is bigger, mutual inductor ratio is also big, is generally 600-2000/5.The primary currents of tens peaces, the electric current that is reacted to secondary is very little, has only several milliamperes to tens milliamperes, when zero-sequence current is 2A when following, the basic no current output of secondary side, it is big to measure difficulty, and measuring accuracy is poor, can't satisfy measurement requirement.The measuring method of two kinds of zero-sequence currents all can not reach the measuring accuracy requirement.Therefore up to the present, 10KV high-tension line small current neutral grounding protection can't realize always.
(3) summary of the invention
The present invention provides a kind of measuring accuracy height, measuring method simple high pressure grounding small current detection method in order to remedy the deficiencies in the prior art.
The present invention is achieved through the following technical solutions:
A kind of method for detecting high voltage grounding small current, its special character is: comprise the steps:
(1) zero sequence current mutual inductor is set on three-phase conductor, between zero sequence current mutual inductor secondary head and the tail, connects resistance, resistance two ends voltage-measuring equipment in parallel;
(2) by the secondary voltage of voltage-measuring equipment measurement current transformer, utilize the Current Transformer Secondary inductive voltage value to determine the primary current value, primary current and secondary induction voltage are proportional.
The present invention is by at the in parallel certain resistance of Current Transformer Secondary, utilizes the Current Transformer Secondary inductive voltage value to determine the primary current value.The present invention includes the zero sequence current mutual inductor that is arranged on the three-phase conductor, be connected the resistance between the zero sequence current mutual inductor secondary head and the tail, a millivolt voltage table (or other voltage-measuring equipments) of resistance two ends parallel connection.
Principle of work of the present invention is: current transformer is under normal operation, and secondary is near short circuit, and voltage is very low.When second open circuit, voltage is very high, can reach several hectovolts or higher.The current transformer primary current is at 5% when following of rated current, and primary current is big more, no-load voltage ratio is big more, and secondary induction voltage is high more, and after the secondary proper resistor in parallel, secondary induction voltage and primary current can be proportional.The present invention is exactly this property of utilizing current transformer, measures primary current by the secondary voltage of measuring current transformer.
Effect of the present invention is: the measuring accuracy height, measuring method is simple.
(4) description of drawings
The present invention is further illustrated below in conjunction with accompanying drawing.
Accompanying drawing is a circuit diagram of the present invention.
Among the figure: A, B, C are the three-phase high-voltage power transmission conductor;
ZCT is a zero sequence current mutual inductor;
R is a parallel resistance;
V is a millivolt voltage table (or other voltage-measuring equipments).
(5) embodiment
Accompanying drawing is a kind of specific embodiment of the present invention.This embodiment is for the DBZW8-12 type outdoor high-voltage ground protection vacuum circuit breaker of our factory development, as the detection of grounding small current.Zero sequence current mutual inductor ZCT at first is set on three-phase conductor, between zero sequence current mutual inductor ZCT secondary head and the tail, connects resistance R, resistance R two ends millivolt voltage table V in parallel; Secondary voltage by millivolt voltage table V measurement current transformer utilizes the Current Transformer Secondary inductive voltage value to determine the primary current value.The no-load voltage ratio that is enclosed within the zero sequence current mutual inductor on the inner three-phase conductor of isolating switch is 2000/1, parallel resistance is 420 Ω, through repeatedly test, when the high pressure single-phase-to-ground current is 0-20A, the zero sequence current mutual inductor secondary induction voltage is 0-4V, and primary current and secondary induction voltage are proportional.
Claims (2)
1. a method for detecting high voltage grounding small current is characterized in that: comprise the steps:
(1) zero sequence current mutual inductor is set on three-phase conductor, between zero sequence current mutual inductor secondary head and the tail, connects resistance, resistance two ends voltage-measuring equipment in parallel;
(2) by the secondary voltage of voltage-measuring equipment measurement current transformer, utilize the Current Transformer Secondary inductive voltage value to determine the primary current value, primary current and secondary induction voltage are proportional.
2. method for detecting high voltage grounding small current according to claim 1 is characterized in that:
Described voltage-measuring equipment is the millivolt voltage table.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100168914A CN101303375A (en) | 2008-06-24 | 2008-06-24 | Method for detecting high voltage grounding small current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100168914A CN101303375A (en) | 2008-06-24 | 2008-06-24 | Method for detecting high voltage grounding small current |
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| Publication Number | Publication Date |
|---|---|
| CN101303375A true CN101303375A (en) | 2008-11-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA2008100168914A Pending CN101303375A (en) | 2008-06-24 | 2008-06-24 | Method for detecting high voltage grounding small current |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111090000A (en) * | 2019-12-23 | 2020-05-01 | 浙江天正电气股份有限公司 | Method capable of realizing high-precision measurement of residual current |
-
2008
- 2008-06-24 CN CNA2008100168914A patent/CN101303375A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111090000A (en) * | 2019-12-23 | 2020-05-01 | 浙江天正电气股份有限公司 | Method capable of realizing high-precision measurement of residual current |
| CN111090000B (en) * | 2019-12-23 | 2022-01-14 | 浙江天正智能电器有限公司 | Method capable of realizing high-precision measurement of residual current |
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Open date: 20081112 |