CN1305085C - Metering type electromagnetic current mutual inductor redidual magnetism inhibiting method - Google Patents
Metering type electromagnetic current mutual inductor redidual magnetism inhibiting method Download PDFInfo
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- CN1305085C CN1305085C CNB2004100427018A CN200410042701A CN1305085C CN 1305085 C CN1305085 C CN 1305085C CN B2004100427018 A CNB2004100427018 A CN B2004100427018A CN 200410042701 A CN200410042701 A CN 200410042701A CN 1305085 C CN1305085 C CN 1305085C
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Abstract
The present invention discloses a metering type electromagnetic current mutual inductor redidual magnetism inhibiting method, which belongs to the technical range of mutual inductor preparation. In the method, a residual magnetism inhibiting device is connected in parallel between the secondary side of a current transformer and a load. The output voltage of the secondary side of the current transformer is restricted to a preset level, and thus, magnetic flux in an iron core is restricted and can not be raised greatly. After a current is stopped, residual magnetism in the iron core is restricted and can not be raised greatly, and the error of the current transformer can also not be raised obviously. No complicated detection and control circuit is the residual magnetism inhibiting device. The present invention is simple and effective and has the advantages of high reliability, low manufacturing cost and easy realization. Simultaneously, the present invention has no obvious influence on the original structure and the normal operation of the current transformer.
Description
Technical field
The invention belongs to instrument transformer manufacturing technology scope, particularly a kind of amount meter type electromagnetic current transducer remanent magnetism restraining device.
Background technology
Amount meter type electromagnetic current transducer is used for the current measurement, electric energy metrical of electric power system etc., and its accuracy is significant, and the running of electricity market is played an important role.The accuracy of now industrial amount meter type current transformer has reached 0.2 grade.Wang Xiaoqi, Guo Keqin, Yao Min, time dawn. document " remanent magnetism is to the influence of current transformer class of accuracy. 1996 06 phases of transformer; 5～9 " report: when electric power system is short-circuited fault, to produce big remanent magnetism in the current transformer, amplitude error is reached more than 0.4%, seriously surpass the nominal error scope.Proposition is made current transformer more than 0.2 grade with little non-crystalline material of coercive force and permalloy, but cost will be multiplied.Report in document " Bruce R.G.; Wright A.Remanent flux in current-transformer cores.Proceedings of the Institution ofElectrical Engineers; v 113; n 5; 1966; 915-920 ", short trouble in the electric power system or the exciting curent in the current transformer are crossed mostly can produce bigger remanent magnetism in current transformer.Bigger remanent magnetism is subjected to bigger harmful effect to the measurement of electric weight and the operate as normal of relay protection device.The physical property of ferromagnetic material has determined will produce remanent magnetism in the ferromagnetic material when exciting curent is decreased to zero.When other condition was constant, exciting curent was big more, and remanent magnetism is also big more.The electric current that the former limit of current transformer was passed through when electric power system normally moved is little, and exciting curent therefore unshakable in one's determination is also less.But when being short-circuited, primary current will increase sharply, and maximum can reach tens times of specified running current, and may have bigger DC component in the short circuit current.Exciting curent will increase this moment.The primary current zero passage stops during the excision short trouble.At this moment, will produce bigger remanent magnetism in the iron core.Because exciting curent is very little during the current transformer operate as normal, the remanent magnetism that produces during to the short circuit magnetic action of not dispelling substantially, thereby the life period of remanent magnetism can surpass some months.Operating characteristic when the existence of remanent magnetism will influence operation of current transformers will hinder accurately and measure.For suppressing remanent magnetism, there is a kind of method to be to use the little ferromagnetic material of coercive force, as permalloy or non-crystalline material, but the price of these materials is higher, will increase the manufacturing cost of instrument transformer exponentially.In addition, in document " Conner E.E.; Greb R.G.; Wentz E.C.Control ofresidual flux in current transformers.IEEE Transactions on Power Apparatus andSystems; v PAS-92; n 4,1973,1226-1233 ", proposed to utilize the method that on iron core, increases by a small air gap to suppress remanent magnetism in the current transformer.The error when but this method will reduce the capacity of instrument transformer and increase operate as normal.But this method will increase leakage field and reduce accuracy of measurement, make also inconvenient.
Summary of the invention
The purpose of this invention is to provide a kind of amount meter type electromagnetic current transducer remanent magnetism restraining device.It is characterized in that: this device is at the secondary of electromagnetic current transducer 1 and loads between 3 and connect remanent magnetism restraining device 2.Remanent magnetism restraining device 2 is actual to be a pressure limiting device, promptly work as short circuit current by current transformer 1 former limit, when current transformer 1 secondary output current surpasses preset threshold, the electric current of current transformer 1 secondary flows through main branch road from remanent magnetism restraining device 2 places, the output voltage of current transformer 1 secondary is limited to preset level simultaneously, magnetic flux in the iron core will not be restricted and can significantly increase, remanent magnetism will be limited in electric current termination back core, can be not excessive, the error of current transformer 1 also can obviously not increase.
Voltage stabilizing that described remanent magnetism restraining device 2 is a differential concatenation or rectifier diode, transient voltage suppress diode or metal oxide varistor etc.
The invention has the beneficial effects as follows does not have complicated detection and control circuit in the remanent magnetism restraining device, effectively simple, the reliability height.Cheap, realize easily.Simultaneously to original structure of current transformer and not obviously influence of operate as normal.
Description of drawings
Fig. 1 is the current transformer schematic diagram that has the remanent magnetism restraining device.
Fig. 2 is several remanent magnetism restraining devices: (a) voltage stabilizing of differential concatenation or rectifier diode; (b) transient voltage suppresses diode; (c) metal oxide varistor.
Embodiment
The present invention is a kind of amount meter type electromagnetic current transducer remanent magnetism restraining device.This device is at the secondary of electromagnetic current transducer 1 and loads between 3 and connect remanent magnetism restraining device 2 (as shown in Figure 1).Under normal running status, the electric current of current transformer 1 secondary is near rated value, at this moment, the remanent magnetism restraining device 2 of actual pressure limiting device is high-impedance state, obstructed overcurrent, electric current all through the 3 branch roads circulation of loading, therefore can not constitute influence to the measurement of electric current and the metering of electric energy.When short circuit current passes through the former limit of instrument transformer, when current transformer secondary output current surpasses preset threshold, remanent magnetism restraining device 2 will become low resistive state by high-impedance state, the electric current of current transformer 1 secondary flows through main branch road by remanent magnetism restraining device 2 places, and the output voltage of current transformer secondary is limited to preset level simultaneously.According to the operation principle of current transformer as can be known: electromotive force and output voltage in the secondary coil are suitable, and the magnetic flux in electromotive force and the iron core is proportional.Therefore, after the output voltage of instrument transformer secondary is restricted, the magnetic flux in the iron core will not be restricted and can significantly increase.Therefore remanent magnetism will be limited under certain level in the electric current termination back core, can be not excessive, and the error of instrument transformer also can obviously not increase.The action adjustable threshold value of remanent magnetism restraining device is to adapt to the situation of different load and operating current.
Figure 2 shows that constituting of remanent magnetism restraining device 2: (a) voltage stabilizing of differential concatenation or rectifier diode; (b) transient voltage inhibition diode or (c) metal oxide varistor.
Claims (1)
1. amount meter type electromagnetic current transducer remanent magnetism restraining device, this device is between the secondary of electromagnetic current transducer (1) and load (3) and connects remanent magnetism restraining device (2); Remanent magnetism restraining device (2) is actual to be a pressure limiting device, promptly work as short circuit current by the former limit of current transformer (1), when current transformer (1) secondary output current surpasses preset threshold, the electric current general of current transformer (1) secondary is mainly flow through from the branch road at remanent magnetism restraining device (2) place, the output voltage of current transformer (1) secondary is limited to preset level simultaneously, magnetic flux in the iron core will not be restricted and can significantly increase, remanent magnetism will be limited in electric current termination back core, can be not excessive, the error of current transformer (1) also can obviously not increase, and it is characterized in that: described remanent magnetism restraining device (2) suppresses diode or metal oxide varistor for transient voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100427018A CN1305085C (en) | 2004-05-21 | 2004-05-21 | Metering type electromagnetic current mutual inductor redidual magnetism inhibiting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100427018A CN1305085C (en) | 2004-05-21 | 2004-05-21 | Metering type electromagnetic current mutual inductor redidual magnetism inhibiting method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1581382A CN1581382A (en) | 2005-02-16 |
| CN1305085C true CN1305085C (en) | 2007-03-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB2004100427018A Expired - Fee Related CN1305085C (en) | 2004-05-21 | 2004-05-21 | Metering type electromagnetic current mutual inductor redidual magnetism inhibiting method |
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| CN (1) | CN1305085C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103969488B (en) * | 2013-01-31 | 2017-09-29 | 西门子公司 | Current transformer and its current detection circuit |
| CN112034231B (en) * | 2020-07-21 | 2022-10-25 | 华北电力大学 | High-frequency current sensor based on frequency-dependent integral resistor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5923548A (en) * | 1997-03-28 | 1999-07-13 | Reltec Corporation | Active clamp used to maintain proper current transformer operation |
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2004
- 2004-05-21 CN CNB2004100427018A patent/CN1305085C/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5923548A (en) * | 1997-03-28 | 1999-07-13 | Reltec Corporation | Active clamp used to maintain proper current transformer operation |
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| CN1581382A (en) | 2005-02-16 |
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Granted publication date: 20070314 Termination date: 20110521 |