CN104297611B - A kind of mutual inductor sample circuit - Google Patents
A kind of mutual inductor sample circuit Download PDFInfo
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- CN104297611B CN104297611B CN201410018981.2A CN201410018981A CN104297611B CN 104297611 B CN104297611 B CN 104297611B CN 201410018981 A CN201410018981 A CN 201410018981A CN 104297611 B CN104297611 B CN 104297611B
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- mutual inductor
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Abstract
The invention discloses a kind of mutual inductor sample circuit, including the sampling resistor for being arranged in transformer secondary side output end, the open circuit for also including being made up of at least one divider resistance and switching tube judges detection circuit, the sampling resistor, divider resistance and switching tube one series arm of formation.The drawbacks of mutual inductor sample circuit of the present invention is connected for existing detector for electric fire protection and creepage mutual inductor, add to transformer on-line testing circuit, sampling resistor, divider resistance and switching tube one series arm of formation, when electric current is 0, series arm is turned on, judges whether transformer opens a way or failure by detecting the magnitude of voltage of sampling resistor.The circuit structure, it is easy to control, commissioning staff and user is got information about the situation of the circuit between creepage mutual inductor and connection detector, can accurately show connection and the broken string of creepage mutual inductor, greatly facilitate grasp transformer state in field adjustable and running.
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 unlike conventional fire automatic alarm system, electricity
It is that, in order to avoid loss, and conventional fire automatic alarm system is to reduce loss that gas fire monitoring system is alarmed in advance.For
Preventing electric fire occurs, and reduces fire hazard, rationally designs electric fire monitoring system, ensures electric fire monitoring system
Construction quality and performance, the protection person and property safety,《Code for fire protection design of high rise buildings》With mandatory national standard
《The installation and operation of aftercurrent action protecting equipment》All highlight aftercurrent action protecting equipment prevent because ground connection therefore
The protective action of electrical fire caused by barrier, it is desirable to residual current acting fire monitoring system is installed in building.
Residual current acting fire monitoring system typically uses creepage mutual inductor, creepage mutual inductor operation principle such as Fig. 1 institutes
Show, if the electric current flowed through in wire is i1, i1 will produce electromagnetic field, power and the electric current in wire of electromagnetic field around it
Size is directly proportional.Current transformer is high permeability device, and it is placed in electromagnetic field, secondarily friendship will be induced in level coil
Time-dependent current i2.I1/n=i2/n is wherein:N is the number of turn of transformer.It can be seen that, i2, i1 is directly proportional.
Under normal circumstances, as shown in Figure 2, the size of current flowed through in L lines and N lines is equal, in the opposite direction.If circuit
Insulation degradation, such as L lines form resistance over the ground, and its electric current is I0, now:I1=I2+I0, then I0=I1-I2 ≠ 0.A in figure
If place, which entangles electric current mutual current transformer in L lines and N lines, the coil of current transformer, to induce the electricity being directly proportional to I0
Stream.Current transformer is arranged at b, I0 can also be equally detected, I0 is referred to as leakage current, its numerical values recited is reflected
The electrical insulation properties of distribution line and electrical equipment.
The connection of current detector for electric fire protection and creepage mutual inductor, is all the output end directly creepage mutual inductor
A sampling resistor in parallel, is converted into the input that voltage signal is followed by A/D converter circuit by current signal, works as creepage mutual inductor
In when thering is the electric current to flow through, A/D converter circuit directly send CPU to calculate sampled data, and it is mutual that detector can just be accurately obtained electric leakage
The electric current that sensor flows through.But this mode has individual shortcoming, 0 is output as when breaking inside transformer, then detector shows electric current
Also it is 0, detector can be judged as that the electric current that flows through is open circuit or erroneous judgement to occur during failure inside 0, i.e. transformer, be lost
The function of being monitored to leakage current.
The content of the invention
It is an object of the invention to provide a kind of mutual inductor sample circuit, there is erroneous judgement now to solve existing creepage mutual inductor
As so that the problem of losing to leakage current function for monitoring.
In order to realize the above object the technical solution adopted in the present invention is：A kind of mutual inductor sample circuit, including for
It is arranged on the sampling resistor in transformer secondary side output end, it is characterised in that：Also include by least one divider resistance and open
Close the open circuit judgement detection circuit that pipe is constituted, the sampling resistor, divider resistance and switching tube one series arm of formation.
The switching tube is triode, and the base stage of the triode and the control end of controller are connected, and its emitter stage is with dividing
Piezoresistance is connected, and colelctor electrode is used to be connected with power supply.
One end of the sampling resistor is connected by amplifying circuit with A/D converter circuit.
The amplifying circuit uses operational amplifier LM2904M.
The disadvantage that the mutual inductor sample circuit of the present invention is connected for existing detector for electric fire protection and creepage mutual inductor
End, adds to transformer on-line testing circuit, connects and be made up of at least one divider resistance and switching tube on sampling resistor
Open circuit judge detection circuit, sampling resistor, divider resistance and switching tube formation one series arm, electric current be 0 when, conducting
Series arm, judges whether transformer opens a way or failure by detecting the magnitude of voltage of sampling resistor.The circuit structure, controlling party
Just, commissioning staff and user is allow to get information about the situation of the circuit between creepage mutual inductor and connection detector, can be with
The connection of accurate display creepage mutual inductor and broken string, greatly facilitate grasp transformer shape in field adjustable and running
State.When leakage current is larger, it is to avoid because influenceing alarm the problem of equipment itself, substantially increase leakage fire alarming equipment
Reliability.
Brief description of the drawings
Fig. 1 is the schematic diagram that current signal is extracted using transformer；
Fig. 2 is leakage current detection principle diagram；
Fig. 3 is mutual inductor sample circuit theory diagrams of the present invention.
Embodiment
Below in conjunction with the accompanying drawings and the present invention is described further specific embodiment.
The schematic diagram of mutual inductor sample circuit embodiments of the present invention is illustrated in figure 3, as seen from the figure, the circuit includes being used for
It is arranged on transformer secondary side output end（I0、COM）Between sampling resistor R2, in addition to by least one divider resistance R1 and
The open circuit that switching tube Q1 is constituted judges detection circuit, sampling resistor R2, divider resistance R1 and one series connection branch of switching tube Q1 formation
Road.
The controller of the present embodiment uses single-chip microcomputer；Switching tube uses triode Q1, model 2N3904, triode Q1's
The control end KL connections of base stage and single-chip microcomputer, its emitter stage is connected with divider resistance, and colelctor electrode is used to be connected with power supply.
Transformer secondary side output end one end is grounded, the other end（Connect sampling resistor R2）One end by amplifying circuit with
A/D converter circuit is connected, and the amplifying circuit uses operational amplifier U1, model LM2904M.
As shown in figure 3, base stages of the control end KL of single-chip microcomputer by resistance R84 and Q1, and resistance R84 one end passes through electricity
Hinder R87 ground connection；Operational amplifier U1 input I01 is connected by resistance R43 with the output end of transformer secondary side；Computing is put
Big device U1 input I01 is also grounded by an electric capacity C1.
The operation principle and process of the present invention is as follows：During normal work, the control end KL of single-chip microcomputer is low, and triode Q1 is not
Voltage signal is converted to through R2 without DC voltage, leakage current signal on conducting, sampling resistor R2, enters A/D converter circuit, is realized just
The functions such as normal leakage current monitoring alarm.
When sample rate current is 0, it is necessary to the open circuit of creepage mutual inductor is detected, judge to be strictly that electric current is zero also
It is due to the broken string or failure of transformer.Now controlling switch KL is set to high by single-chip microcomputer, triode Q1 conductings, sampling resistor R2
On have DC voltage, if transformer is normal, DC internal resistance very little, resistance is close to 0 when it is in parallel with sampling resistor R2（Actual measurement
30 ohm）, then the DC voltage of AD conversion is also close to 0, and now single-chip microcomputer prompting transformer is normal；Do not connect when transformer or
Inside broken string when, infinite, it is in parallel with sampling resistor R2 after, internal resistance can be ignored, and resistance in parallel is close to R2's
The magnitude of voltage that DC voltage after resistance, AD conversion is R2 in series arm（More than 0）, now detector prompting mulual inductor malfunction
Or do not connect.
Claims (3)
1. a kind of mutual inductor sample circuit, including the sampling resistor for being arranged in transformer secondary side output end, its feature
It is：The open circuit for also including being made up of at least one divider resistance and switching tube judges detection circuit, the sampling resistor, partial pressure
Resistance and switching tube one series arm of formation；Judge whether transformer opens a way or event by detecting the magnitude of voltage of sampling resistor
Barrier；The switching tube is triode, and the base stage of the triode and the control end of controller are connected, its emitter stage and divider resistance
Connection, colelctor electrode is used to be connected with power supply.
2. mutual inductor sample circuit according to claim 1, it is characterised in that：One end of the sampling resistor passes through amplification
Circuit is connected with A/D converter circuit.
3. mutual inductor sample circuit according to claim 2, it is characterised in that：The amplifying circuit uses 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 |
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| Publication Number | Publication Date |
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| CN104297611A CN104297611A (en) | 2015-01-21 |
| CN104297611B true CN104297611B (en) | 2017-10-27 |
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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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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3682930B2 (en) * | 1994-09-26 | 2005-08-17 | 株式会社東芝 | Insulation deterioration diagnosis device |
| 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 |
| CN201402962Y (en) * | 2009-03-11 | 2010-02-10 | 福建俊豪电子有限公司 | Electric fire detection control integrated system |
| CN101666846B (en) * | 2009-09-25 | 2012-09-12 | 深圳市科陆电子科技股份有限公司 | System and method for detecting anomaly of secondary wiring of current mutual inductor |
| 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 |
| CN103308807B (en) * | 2013-06-19 | 2015-04-01 | 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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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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