CN105486971A - Short circuit and open circuit state detection circuit for secondary side winding of current transformer - Google Patents
Short circuit and open circuit state detection circuit for secondary side winding of current transformer Download PDFInfo
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- CN105486971A CN105486971A CN201510792009.5A CN201510792009A CN105486971A CN 105486971 A CN105486971 A CN 105486971A CN 201510792009 A CN201510792009 A CN 201510792009A CN 105486971 A CN105486971 A CN 105486971A
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- circuit
- secondary side
- resistance
- operational amplifier
- current transformer
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/72—Testing of electric windings
Abstract
The invention discloses a short circuit and open circuit state detection circuit for a secondary side winding of a current transformer. The circuit can output voltage which accurately reflects that the secondary side winding of the current transformer is in short circuit, open circuit, or a normal state, so as to determine the short circuit, open circuit, or normal state of the secondary side winding of the current transformer. The short circuit and open circuit state detection circuit for a secondary side winding of a current transformer comprises a signal sampling circuit, a secondary side winding state judgement circuit, and a constant current source circuit used to provide constant current. The signal sampling circuit comprises sampling resistors connected in parallel with the secondary side winding of the current transformer, a plurality of diodes are connected in series, and the anode of the diodes is connected with the first end of the sampling resistor, and the cathode is connected with ground. The output end of the constant current source circuit is connected with the second end of the sampling resistor, so as to provide operating voltage for the signal sampling circuit. Voltage on two ends of the sampling resistors outputs a voltage signal through the secondary side winding state judgement circuit.
Description
Technical field
The present invention relates to a kind of Current Transformer Secondary side short circuit open-circuit condition measurement circuit design, particularly relate to a kind of with the circuit design of low cost high accuracy high efficient detection Current Transformer Secondary side short circuit open-circuit condition.
Background technology
Current transformer (Currenttransformer is called for short CT) can be converted to the less secondary current of numerical value primary current larger for numerical value by certain no-load voltage ratio.Therefore in the occasion being much applied to big current, all need to use CT to realize the functions such as protection, measurement.And to have in the mode of connection of CT be that form with connecting line connects greatly.Under this connected mode, likely there is the failure condition such as secondary side winding short circuit, open circuit of CT.It is abnormal that these faults can cause the metering circuit of rear class to be measured on the one hand, also can cause certain damage to CT itself on the other hand.Therefore detecting the short circuit of CT secondary side winding open circuit is a very necessary job.Current testing circuit is adopt to access a transformer again in secondary side winding mostly, and the square wave adding certain frequency in the weak side of transformer detects.Such method is all quite troublesome from hardware or software respective, does not all quite calculate from the aspect such as cost, development progress.
Summary of the invention
The object of the invention is to carry a kind of Current Transformer Secondary side short circuit in winding open-circuit condition testing circuit, it is exportable can reflect that Current Transformer Secondary side winding is in short circuit exactly, the voltage of open circuit or normal condition, thus the short circuit of Current Transformer Secondary side winding can be judged, open circuit or normal condition, do not affect the measurement of rear class metering circuit simultaneously, the existing method and this testing circuit is compared, all simplify many from hardware or software, thus achieve low cost high accuracy and detect Current Transformer Secondary side short circuit open-circuit condition expeditiously.
For solving the problems of the technologies described above, the object of the present invention is achieved like this:
A kind of current transformer short circuit open-circuit condition testing circuit, comprises signal sample circuit, secondary side winding status determination circuit, for providing the constant-current source circuit of steady current; Wherein, signal sample circuit comprises the sampling resistor be connected in parallel on the winding of Current Transformer Secondary side, and multiple diode serial connections its anode rear is connected on the first end of sampling resistor, its plus earth; The output terminal of constant-current source circuit is connected on the second end of sampling resistor, for signal sample circuit provides operating voltage; The voltage at sampling resistor two ends is through secondary side winding status determination circuit output voltage signal.
On the basis of such scheme and as the preferred version of such scheme: described diode is 3.
On the basis of such scheme and as the preferred version of such scheme: described secondary side winding status determination circuit comprises the 6th resistance, one end of 6th resistance is connected on the in-phase input end of the 3rd operational amplifier, and the in-phase input end of the 3rd operational amplifier is through the second capacity earth; One end of 7th resistance is connected on the inverting input of the 3rd operational amplifier, the inverting input of the 3rd operational amplifier is connected to through the 8th resistance on the output terminal of the 3rd operational amplifier, and the output terminal of the 3rd operational amplifier is through the 9th resistance output voltage signal; The other end of the 6th resistance is connected on the second end of sampling resistor, and the other end of the 7th resistance is connected on the first end of sampling resistor.
On the basis of such scheme and as the preferred version of such scheme: described constant-current source circuit comprises its negative electrode, with reference to the stabilivolt be connected on power supply, the anode of stabilivolt connects digitally through the first resistance, and the anode of stabilivolt is connected to by the second resistance on the in-phase input end of the second operational amplifier simultaneously; Power supply is connected on the inverting input of the second operational amplifier through the 3rd resistance, the inverting input of the second operational amplifier is connected on the emitter of PNP triode simultaneously, the output terminal of the 3rd operational amplifier is connected in the base stage of PNP triode through the 4th resistance, and the collector of PNP triode is as the output terminal of this constant-current source circuit.
On the basis of such scheme and as the preferred version of such scheme: also comprise circuitry for signal measurement, one end first electric capacity of sampling resistor connects described circuitry for signal measurement, and circuitry for signal measurement is used for the voltage signal size at calculating sampling resistance two ends.
The present invention gives prominence to compared to existing technology and useful technique effect is:
Current Transformer Secondary side of the present invention short circuit in winding open-circuit condition testing circuit, have employed signal sample circuit, secondary side winding status determination circuit and constant-current source circuit structure, the parallel relationship of sampling resistor summation current transformer secondary side winding, the short circuit of Current Transformer Secondary side winding, open circuit, normally all can produce different pressure drops to sampling resistor R5, the voltage at sampling resistor R5 two ends has carried out filtering through secondary side winding status determination circuit, amplify, to export different magnitude of voltage when Current Transformer Secondary side winding is under different conditions, then the short circuit of CT can be judged according to different magnitudes of voltage, open circuit, the state such as normal.When not affecting normal measurement, can fast, efficient, low cost, the short circuit detecting current transformer exactly, open circuit, the state such as normal, the unusual condition that Timeliness coverage current transformer exists, makes related personnel to take measures in time, prevents unexpected generation.
Accompanying drawing explanation
Fig. 1 is circuit diagram of the present invention.
Fig. 2 is the secondary side winding voltage signal figure corresponding when short circuit, open circuit, normal condition.
Embodiment
Below in conjunction with accompanying drawing, with specific embodiment, the invention will be further described, see Fig. 1-Fig. 2;
It should be noted that, the term such as " first ", " second ", " the 3rd ", " the 4th ", " the 6th ", " the 7th ", " the 8th ", " the 9th " mentioned is in the present embodiment not to the restriction quantitatively of correlation technique feature, but in order to distinguish the name that correlation technique feature is made.
This gives a kind of current transformer short circuit open-circuit condition testing circuit, comprise signal sample circuit 2, secondary side winding status determination circuit 4 and constant-current source circuit 1.Wherein, signal sample circuit 2 comprises the sampling resistor R5 be connected in parallel on the winding of Current Transformer Secondary side, and multiple diode serial connections its anode rear is connected on the first end of sampling resistor R5, its plus earth.Constant-current source circuit 1 is for providing steady current, and its output terminal is connected on second end of sampling resistor R5, for signal sample circuit 2 provides operating voltage; The voltage at sampling resistor R5 two ends is through secondary side winding status determination circuit 4 output voltage signal.
In the present embodiment, constant-current source circuit 1 comprises stabilivolt U1, the first resistance R1, the second resistance R2, the 3rd resistance R3, the 4th resistance R4, the second operational amplifier U2, PNP triode Q1.Power supply connects negative electrode and the reference of stabilivolt U1, for providing a reference voltage.The anode of stabilivolt U1 connects digitally by the first resistance R1, the anode of stabilivolt U1 is connected to the in-phase input end of operational amplifier U2 by the second resistance R2 simultaneously, the inverting input of the second operational amplifier U2 is connected to one end of the 3rd resistance R3, and the other end of the 3rd resistance R3 is connected to power supply.R3 determines the size of current of constant current source.The inverting input of the second operational amplifier U2 connects the emitter of PNP triode Q1 simultaneously, and the base stage of PNP triode Q1 connects the output terminal of the second operational amplifier U2 by the 4th resistance R4.The collector of PNP triode Q1 is as the output terminal of this constant-current source circuit, and it exports is the constant current source of a current constant.In the present embodiment, the second operational amplifier adopts single power supply.
In the present embodiment, signal sample circuit includes Current Transmit, sampling resistor R5, diode D1, D2, D3.Current Transmit secondary side winding is connected to sampling resistor R5.One end of sampling resistor R5 is connected to constant current source, diode D1, and after D2, D3 series connection, anode is connected to the other end of sampling resistor R5, and negative electrode connects digitally.After D1, D2, D3 series connection, ground connection has raised level, is applied to late-class circuit.Certainly, the quantity for the diode be connected in series not only can adopt 3, can adopt 2, and 4 even more.
In the present embodiment, secondary side winding status determination circuit includes the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the second electric capacity C2, the 3rd operational amplifier U3.Second end of sampling resistor R5 is connected to the normal phase input end of the 3rd operational amplifier U3 by resistance R6, the normal phase input end of the 3rd operational amplifier U3 is by the second electric capacity C2 ground connection, the other end of sampling resistor R5 is connected to the inverting input of the 3rd operational amplifier U3 by the 7th resistance R7, the inverting input of the 3rd operational amplifier U3 is connected to the output terminal of the 3rd operational amplifier U3 by the 8th resistance R8, the output terminal of the 3rd operational amplifier U3 is by the 9th resistance R9 output voltage signal.This voltage signal can change with the change of the short circuit of Current Transmit secondary side winding, open circuit, the state such as normal, and output voltage signal as shown in Figure 2.Output voltage has three kinds of situations: between U1-U2, between U3-U4, between U5-U6, and secondary side winding short circuit, the CT of difference corresponding current mutual inductor CT are normal, CT open circuit.It can adopt interlock circuit to judge magnitude of voltage, draws current transformer CT secondary side winding current state.Preferably, the signal magnitude at circuitry for signal measurement calculating sampling resistance R5 two ends is accessed in one end of sampling resistor R5 by the first electric capacity C1, one C1 is used for isolated DC signal, guarantee only has AC signal to pass through, and circuitry for signal measurement judges the state of Current Transmit first side winding by this AC signal.
During the work of this testing circuit, constant-current source circuit provides a constant current source, and the size of constant current source is determined by the 3rd resistance R3.Constant current source flows through sampling resistor summation current transformer secondary side winding and produces pressure drop.Due to the parallel relationship of sampling resistor summation current transformer secondary side winding, short circuit, the open circuit of Current Transformer Secondary side winding, normally all can produce different pressure drops to sampling resistor R5, the voltage at sampling resistor R5 two ends has carried out filtering through secondary side winding status determination circuit, amplify, to export different magnitude of voltage when Current Transformer Secondary side winding is under different conditions, then the short circuit of Current Transmit secondary side winding, open circuit, the state such as normal can be judged according to different magnitudes of voltage.
Certainly, in order to the state of Current Transmit secondary side winding can be learnt more intuitively, other functions such as display, communication are also comprised to demonstrate the state of CT in the present embodiment, specifically, output voltage is connected to MCU, MCU, by measuring the magnitude of voltage of input, then exports three kinds of different voltages, directly can judge the state of Current Transformer Secondary side winding whereby when being in three kinds of shapes according to secondary side winding.
Above-described embodiment is only preferred embodiment of the present invention, not limits the scope of the invention according to this, therefore: all equivalence changes done according to structure of the present invention, shape, principle, all should be covered by within protection scope of the present invention.
Claims (5)
1. a Current Transformer Secondary side short circuit in winding open-circuit condition testing circuit, is characterized in that: comprise signal sample circuit, secondary side winding status determination circuit, for providing the constant-current source circuit of steady current; Wherein, signal sample circuit comprises the sampling resistor be connected in parallel on the winding of Current Transformer Secondary side, and multiple diode serial connections its anode rear is connected on the first end of sampling resistor, its plus earth; The output terminal of constant-current source circuit is connected on the second end of sampling resistor, for signal sample circuit provides operating voltage; The voltage at sampling resistor two ends is through secondary side winding status determination circuit output voltage signal.
2. Current Transformer Secondary side according to claim 1 short circuit in winding open-circuit condition testing circuit, is characterized in that: described diode is 3.
3. Current Transformer Secondary side according to claim 1 short circuit in winding open-circuit condition testing circuit, it is characterized in that: described secondary side winding status determination circuit comprises the 6th resistance, one end of 6th resistance is connected on the in-phase input end of the 3rd operational amplifier, and the in-phase input end of the 3rd operational amplifier is through the second capacity earth; One end of 7th resistance is connected on the inverting input of the 3rd operational amplifier, the inverting input of the 3rd operational amplifier is connected to through the 8th resistance on the output terminal of the 3rd operational amplifier, and the output terminal of the 3rd operational amplifier is through the 9th resistance output voltage signal; The other end of the 6th resistance is connected on the second end of sampling resistor, and the other end of the 7th resistance is connected on the first end of sampling resistor.
4. Current Transformer Secondary side according to claim 1 short circuit in winding open-circuit condition testing circuit, it is characterized in that: described constant-current source circuit comprises its negative electrode, with reference to the stabilivolt be connected on power supply, the anode of stabilivolt connects digitally through the first resistance, and the anode of stabilivolt is connected to by the second resistance on the in-phase input end of the second operational amplifier simultaneously; Power supply is connected on the inverting input of the second operational amplifier through the 3rd resistance, the inverting input of the second operational amplifier is connected on the emitter of PNP triode simultaneously, the output terminal of the 3rd operational amplifier is connected in the base stage of PNP triode through the 4th resistance, and the collector of PNP triode is as the output terminal of this constant-current source circuit.
5. Current Transformer Secondary side according to claim 1 short circuit in winding open-circuit condition testing circuit, it is characterized in that: also comprise circuitry for signal measurement, one end first electric capacity of sampling resistor connects described circuitry for signal measurement, and circuitry for signal measurement is used for the voltage signal size at calculating sampling resistance two ends.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201510792009.5A CN105486971A (en) | 2015-11-13 | 2015-11-13 | Short circuit and open circuit state detection circuit for secondary side winding of current transformer |
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| CN201510792009.5A CN105486971A (en) | 2015-11-13 | 2015-11-13 | Short circuit and open circuit state detection circuit for secondary side winding of current transformer |
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| CN105486971A true CN105486971A (en) | 2016-04-13 |
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| CN201510792009.5A Pending CN105486971A (en) | 2015-11-13 | 2015-11-13 | Short circuit and open circuit state detection circuit for secondary side winding of current transformer |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106226638A (en) * | 2016-08-26 | 2016-12-14 | 四川和中电力科技有限公司 | A kind of low voltage mutual inductor measurement loop state on_line monitoring system |
| CN106371049A (en) * | 2016-08-31 | 2017-02-01 | 贵州电网有限责任公司贵阳供电局 | Current transformer secondary open circuit identification method |
| CN107037303A (en) * | 2016-11-07 | 2017-08-11 | 北京博纳电气股份有限公司 | Detection means and detection method for tested CT secondary side circuit states outside ammeter |
| CN110531214A (en) * | 2019-08-28 | 2019-12-03 | 中广核工程有限公司 | For detecting the detection verification method of Secondary Circuit of Potential Transformer winding short circuit |
| CN112925373A (en) * | 2021-01-27 | 2021-06-08 | 南京丹迪克电力仪表有限公司 | Multi-range constant current source circuit, multi-range constant current source and control method |
| CN113721180A (en) * | 2021-06-18 | 2021-11-30 | 河南力安测控科技有限公司 | Detection circuit and detection method for residual current transformer |
| CN117117805A (en) * | 2023-08-23 | 2023-11-24 | 广东开放大学（广东理工职业学院） | Open-circuit protection method for current transformer |
| EP4075619A4 (en) * | 2019-12-12 | 2024-01-17 | Ls Electric Co Ltd | Protective relay and method for detecting disconnection of protective relay |
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| US6937483B2 (en) * | 2002-01-16 | 2005-08-30 | Ballard Power Systems Corporation | Device and method of commutation control for an isolated boost converter |
| CN102508148A (en) * | 2011-11-04 | 2012-06-20 | 深圳市领步科技有限公司 | Power detection device supporting hotplug, current input module and realizing method |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106226638A (en) * | 2016-08-26 | 2016-12-14 | 四川和中电力科技有限公司 | A kind of low voltage mutual inductor measurement loop state on_line monitoring system |
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| CN106371049B (en) * | 2016-08-31 | 2023-09-26 | 贵州电网有限责任公司贵阳供电局 | Current transformer secondary open circuit identification method |
| CN107037303A (en) * | 2016-11-07 | 2017-08-11 | 北京博纳电气股份有限公司 | Detection means and detection method for tested CT secondary side circuit states outside ammeter |
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| CN110531214B (en) * | 2019-08-28 | 2022-06-07 | 中广核工程有限公司 | Detection and verification method for detecting short circuit of secondary circuit winding of voltage transformer |
| EP4075619A4 (en) * | 2019-12-12 | 2024-01-17 | Ls Electric Co Ltd | Protective relay and method for detecting disconnection of protective relay |
| CN112925373A (en) * | 2021-01-27 | 2021-06-08 | 南京丹迪克电力仪表有限公司 | Multi-range constant current source circuit, multi-range constant current source and control method |
| CN113721180A (en) * | 2021-06-18 | 2021-11-30 | 河南力安测控科技有限公司 | Detection circuit and detection method for residual current transformer |
| CN117117805A (en) * | 2023-08-23 | 2023-11-24 | 广东开放大学（广东理工职业学院） | Open-circuit protection method for current transformer |
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Application publication date: 20160413 |