CN104297611A - Transformer sampling circuit - Google Patents
Transformer sampling circuit Download PDFInfo
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- CN104297611A CN104297611A CN201410018981.2A CN201410018981A CN104297611A CN 104297611 A CN104297611 A CN 104297611A CN 201410018981 A CN201410018981 A CN 201410018981A CN 104297611 A CN104297611 A CN 104297611A
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Abstract
The invention discloses a transformer sampling circuit which comprises a sampling resistor arranged at the output end of the secondary side of a transformer. The transformer sampling circuit also comprises an open circuit judgment detection circuit formed by at least one voltage divider resistor and a switch tube, wherein the sampling resistor, the voltage divider resistor and the switch tube form a series branch. According to the transformer sampling circuit, targeted for the defects of connection of an electrical fire monitor detector and an electric leakage transformer at present, an online transformer test circuit is added; and the sampling resistor, the voltage divider resistor and the switch tube are utilized to form a series branch, and when the current is 0, the series branch is connected, and whether the transformer is open circuited or breaks down is judged by detecting the voltage value of the sampling resistor. The circuit is simple in structure and easy to control; debugging personnel are allowed to know the line condition between the electric leakage transformer and a connection detector visually, connection and disconnection of the electric leakage transformer can be displayed accurately, and the condition of the transformer can be known in the field debugging and operation process with great convenience.
Description
Technical field
The present invention relates to a kind of mutual inductor sample circuit.
Background technology
Electric fire monitoring system belongs to pre-alarm system in advance, and reporting to the police in advance unlike, electric fire monitoring system with conventional fire automatic alarm system is in order to avoid loss, and conventional fire automatic alarm system is to reduce the loss.For preventing electric fire occurs; reduce fire hazard; appropriate design electric fire monitoring system; ensure construction quality and the usability of electric fire monitoring system; the protection person and property safety; " Code for fire protection design of high rise buildings " and mandatory GB " installation and operation of aftercurrent action protecting equipment " all highlight the protective action of aftercurrent action protecting equipment at the electrical fire preventing from causing because of earth fault, require in buildings, install residual current acting fire monitoring system.
Residual current acting fire monitoring system generally adopts creepage mutual inductor, and as shown in Figure 1, will generate an electromagnetic field around it if the electric current flow through in wire is i1, i1, the power of electromagnetic field is directly proportional to the size of current in wire creepage mutual inductor principle of work.Current transformer is high permeability device, and it is placed in elect magnetic field, will induce exchange current i2 secondarily in level coil.I1/n=i2/n is wherein: n is the number of turn of mutual inductor.Visible, i2, i1 are directly proportional.
As shown in Figure 2, under normal circumstances, the size of current flow through in L line and N line is equal, and direction is contrary.If line insulation is deteriorated, such as L line forms resistance over the ground, and its electric current is I0, now: I1=I2+I0, then and I0=I1-I2 ≠ 0.If mutual for electric current current transformer is entangled L line and N line by a place in the drawings, then the electric current be directly proportional to I0 will be induced in the coil of current transformer.Current transformer is arranged on b place, equally also can detects I0, I0 is called leakage current, its numerical values recited reflects the electrical insulation properties of distribution line and electrical equipment.
The connection of current detector for electric fire protection and creepage mutual inductor, all directly a sampling resistor in parallel for the output terminal of creepage mutual inductor, the input end of A/D convertor circuit is connect after current signal being converted to voltage signal, when there being electric current to flow through in creepage mutual inductor, A/D convertor circuit directly send CPU to calculate sampled data, and detector just can obtain the electric current that creepage mutual inductor flows through accurately.But this mode has individual shortcoming, exporting when mutual inductor inside broken string is 0, then detector display electric current is also 0, and detector can be judged as that the electric current flow through is 0, namely there will be erroneous judgement when mutual inductor inside open circuit or fault, lose the function that leakage current is monitored.
Summary of the invention
The object of this invention is to provide a kind of mutual inductor sample circuit, occur misjudgment phenomenon to solve existing creepage mutual inductor, thus lose the problem to leakage current function for monitoring.
In order to realize above object, the technical solution adopted in the present invention is: a kind of mutual inductor sample circuit, comprise the sampling resistor for being arranged on mutual inductor secondary side output terminal, it is characterized in that: also comprise the open circuit be made up of at least one divider resistance and switching tube and judge testing circuit, described sampling resistor, divider resistance and switching tube form a series arm.
Described switching tube is triode, and the base stage of described triode is connected with the control end of controller, and its emitter is connected with divider resistance, and collector is used for being connected with power supply.
One end of described sampling resistor is connected with A/D convertor circuit by amplifying circuit.
Described amplifying circuit adopts operational amplifier LM2904M.
The drawback that mutual inductor sample circuit of the present invention is connected with creepage mutual inductor for existing detector for electric fire protection, add mutual inductor on-line testing circuit, the open circuit be made up of at least one divider resistance and switching tube that sampling resistor is connected judges testing circuit, sampling resistor, divider resistance and switching tube form a series arm, when electric current is 0, by the magnitude of voltage detecting sampling resistor, conducting series arm, judges whether mutual inductor opens a way or fault.This circuit structure, it is convenient to control, make commissioning staff and user can get information about creepage mutual inductor and connect the situation of the circuit between detector, accurately can show connection and the broken string of creepage mutual inductor, greatly facilitate in field adjustable and operational process and grasp mutual inductor state.When leakage current is larger, avoids affecting warning because of the problem of equipment itself, substantially increase the reliability of leakage fire alarming equipment.
Accompanying drawing explanation
Fig. 1 is the schematic diagram utilizing mutual inductor to extract current signal;
Fig. 2 is leakage current Cleaning Principle figure;
Fig. 3 is mutual inductor sample circuit theory diagrams of the present invention.
Embodiment
Below in conjunction with accompanying drawing and specific embodiment, the present invention is described further.
Be illustrated in figure 3 the schematic diagram of mutual inductor sample circuit embodiments of the present invention, as seen from the figure, this circuit comprises the sampling resistor R2 for being arranged between mutual inductor secondary side output terminal (I0, COM), also comprise the open circuit be made up of at least one divider resistance R1 and switching tube Q1 and judge testing circuit, sampling resistor R2, divider resistance R1 and switching tube Q1 form a series arm.
The controller of the present embodiment adopts single-chip microcomputer; Switching tube adopts triode Q1, and model is 2N3904, and the base stage of triode Q1 is connected with the control end KL of single-chip microcomputer, and its emitter is connected with divider resistance, and collector is used for being connected with power supply.
Mutual inductor secondary side output terminal one end ground connection, one end of the other end (connecting sampling resistor R2) is connected with A/D convertor circuit by amplifying circuit, and this amplifying circuit adopts operational amplifier U1, and model is LM2904M.
As shown in Figure 3, the control end KL of single-chip microcomputer passes through the base stage of resistance R84 and Q1, and one end of resistance R84 is by resistance R87 ground connection; The input end I01 of operational amplifier U1 is connected with the output terminal of mutual inductor secondary side by resistance R43; The input end I01 of operational amplifier U1 is also by an electric capacity C1 ground connection.
Principle of work of the present invention and process as follows: when normally working, the control end KL of single-chip microcomputer is low, triode Q1 not conducting, without DC voltage on sampling resistor R2, leakage current signal is converted to voltage signal through R2, enters A/D convertor circuit, realizes normal leakage current and monitors the functions such as warning.
When sample rate current is 0, carry out detecting the open circuit of creepage mutual inductor with regard to needing, to be electric current be really zero or due to the broken string of mutual inductor or fault in judgement.Now single-chip microcomputer is set to height controlling pin KL, triode Q1 conducting, sampling resistor R2 there is DC voltage, if when mutual inductor is normal, DC internal resistance is very little, when it is in parallel with sampling resistor R2, resistance surveys 30 ohm close to 0(), then the DC voltage of AD conversion is also close to 0, and now single-chip microcomputer prompting mutual inductor is normal; When mutual inductor does not connect or break in inside, infinite, after in parallel with sampling resistor R2, internal resistance is negligible, resistance in parallel is close to the resistance of R2, DC voltage after AD conversion is the magnitude of voltage (being greater than 0) of R2 in series arm, and now detector is pointed out mulual inductor malfunction or do not connect.
Claims (4)
1. a mutual inductor sample circuit, comprise the sampling resistor for being arranged on mutual inductor secondary side output terminal, it is characterized in that: also comprise the open circuit be made up of at least one divider resistance and switching tube and judge testing circuit, described sampling resistor, divider resistance and switching tube form a series arm.
2. mutual inductor sample circuit according to claim 1, is characterized in that: described switching tube is triode, and the base stage of described triode is connected with the control end of controller, and its emitter is connected with divider resistance, and collector is used for being connected with power supply.
3. mutual inductor sample circuit according to claim 1, is characterized in that: one end of described sampling resistor is connected with A/D convertor circuit by amplifying circuit.
4. the mutual inductor sample circuit according to claims 1 to 3 any one, is characterized in that: described amplifying circuit adopts operational amplifier LM2904M.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410018981.2A CN104297611B (en) | 2014-01-14 | 2014-01-14 | A kind of mutual inductor sample circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410018981.2A CN104297611B (en) | 2014-01-14 | 2014-01-14 | A kind of mutual inductor sample circuit |
Publications (2)
| Publication Number | Publication Date |
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| CN104297611A true CN104297611A (en) | 2015-01-21 |
| CN104297611B CN104297611B (en) | 2017-10-27 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201410018981.2A Active CN104297611B (en) | 2014-01-14 | 2014-01-14 | A kind of mutual inductor sample circuit |
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| CN (1) | CN104297611B (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105242167A (en) * | 2015-10-20 | 2016-01-13 | 中国南方电网有限责任公司 | Substation conventional sampling instrument transformer secondary loop fracture online detection method |
| CN105425067A (en) * | 2015-11-19 | 2016-03-23 | 南京大全电气研究院有限公司 | Method for testing residual current protection electric appliance |
| CN105445537A (en) * | 2015-12-29 | 2016-03-30 | 威特龙消防安全集团股份公司 | Instrument transformer detection device and method |
| CN109932673A (en) * | 2017-12-19 | 2019-06-25 | 上海亿盟电气自动化技术有限公司 | A kind of transformer disconnection detection circuit of breaker |
| CN109960240A (en) * | 2017-12-26 | 2019-07-02 | 宁波菲仕电机技术有限公司 | Wire breakage detector and method based on MCU analog interface wiring |
| CN112379308A (en) * | 2020-10-23 | 2021-02-19 | 许继集团有限公司 | Current transformer secondary side circuit and disconnection detection method thereof |
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| CN201060739Y (en) * | 2007-06-12 | 2008-05-14 | 天津市中天峰电器有限公司 | Mutual inductor with self-circuit open circuit and short circuit detection function |
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| CN202383229U (en) * | 2011-12-31 | 2012-08-15 | 山东亿玛信诺电气有限公司 | Output open circuit monitoring device of current transformer |
| CN103308807A (en) * | 2013-06-19 | 2013-09-18 | 常熟开关制造有限公司(原常熟开关厂） | Transformer state detection device and breaker |
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| JPH0894682A (en) * | 1994-09-26 | 1996-04-12 | Toshiba Corp | Apparatus for diagnosing insulation deterioration |
| CN201060739Y (en) * | 2007-06-12 | 2008-05-14 | 天津市中天峰电器有限公司 | Mutual inductor with self-circuit open circuit and short circuit detection function |
| CN201184891Y (en) * | 2008-01-11 | 2009-01-21 | 俞盛荣 | Detection module for short/open circuit of current mutual inductor secondary circuit |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105242167A (en) * | 2015-10-20 | 2016-01-13 | 中国南方电网有限责任公司 | Substation conventional sampling instrument transformer secondary loop fracture online detection method |
| CN105242167B (en) * | 2015-10-20 | 2017-11-03 | 中国南方电网有限责任公司 | Transformer station's routine sampling instrument transformer secondary circuit broken string online test method |
| CN105425067A (en) * | 2015-11-19 | 2016-03-23 | 南京大全电气研究院有限公司 | Method for testing residual current protection electric appliance |
| CN105445537A (en) * | 2015-12-29 | 2016-03-30 | 威特龙消防安全集团股份公司 | Instrument transformer detection device and method |
| CN109932673A (en) * | 2017-12-19 | 2019-06-25 | 上海亿盟电气自动化技术有限公司 | A kind of transformer disconnection detection circuit of breaker |
| CN109960240A (en) * | 2017-12-26 | 2019-07-02 | 宁波菲仕电机技术有限公司 | Wire breakage detector and method based on MCU analog interface wiring |
| CN112379308A (en) * | 2020-10-23 | 2021-02-19 | 许继集团有限公司 | Current transformer secondary side circuit and disconnection detection method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104297611B (en) | 2017-10-27 |
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Address after: Xuchang City, Henan province 461000 China Electric Valley XJ Group New Energy Industrial Park Applicant after: The Henan intelligent Science and Technology Co., Ltd. that permitted to continue Address before: Xuchang City, Henan province 461000 China Electric Valley XJ Group New Energy Industrial Park Applicant before: HENAN XJ INTELLIGENT CONTROL TECHNOLOGY CO., LTD. |
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Address after: Xuchang City, Henan province 461000 China Electric Valley XJ Group New Energy Industrial Park Applicant after: Xuchang smart relay Limited by Share Ltd Address before: Xuchang City, Henan province 461000 China Electric Valley XJ Group New Energy Industrial Park Applicant before: The Henan intelligent Science and Technology Co., Ltd. that permitted to continue |
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Inventor after: Liu Yongxiang Inventor after: Wang Xiangkun Inventor after: Xi Yaju Inventor after: Cheng Yanbo Inventor after: Guo Xiangyu Inventor after: Hu Chaoran Inventor after: Li Ruxiao Inventor after: Tian Zhenjun Inventor after: Li Xuyong Inventor after: Wang Hongliang Inventor after: Zhang Wenjun Inventor after: Yang Yang Inventor after: Zhu Ningchao Inventor after: Cheng Yinsha Inventor before: Zhang Hongtao Inventor before: Guo Xiangyu Inventor before: Li Ruxiao Inventor before: Liu Yongxiang Inventor before: Tian Zhenjun Inventor before: Cheng Yinsha Inventor before: Li Xuyong Inventor before: Zhang Wenjun Inventor before: Wang Hongliang Inventor before: Yin Fawang |
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