CN201373892Y - Real-time detection circuit for preventing electricity-stealing in current method - Google Patents
Real-time detection circuit for preventing electricity-stealing in current method Download PDFInfo
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- CN201373892Y CN201373892Y CN200920088632U CN200920088632U CN201373892Y CN 201373892 Y CN201373892 Y CN 201373892Y CN 200920088632 U CN200920088632 U CN 200920088632U CN 200920088632 U CN200920088632 U CN 200920088632U CN 201373892 Y CN201373892 Y CN 201373892Y
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Abstract
The utility model discloses a real-time detection circuit for preventing electricity-stealing by a current method. The circuit comprises a signal transmitter (ST), an impedance matching circuit, a high frequency oscillating circuit, a signal processing circuit, a microprocessor (MCU) and an alternating current sampling circuit. A secondary coil of the signal transmitter (ST) is connected with a secondary circuit of a current transformer (CT) in series and a primary coil is connected with the high frequency oscillating circuit; the impedance matching circuit comprises a resistor (R) and a capacitor (C) which are connected in parallel, and forms an (RLC) parallel circuit with the primary coil of (ST) and the secondary coil of (CT); the high frequency oscillating circuit is connected with the input end of the primary coil of (ST) in series, the signal processing circuit is connected with the output end of the primary coil of (ST) in series, and the output end of the signal processing circuit is connected with the A/D converting port of the MCU. The circuit has simple structure, small volume and light weight and can be embedded in metrical equipment conveniently without changing the external interface of the metrical equipment, thus being convenient for users. The circuit can detect electricity-stealing activities that occur in a CT metrical circuit quickly and accurately.
Description
Technical field
The utility model belongs to the anti-electricity-theft applied technical field of electric energy measuring equipment, and what relate generally to is anti-current method stealing real-time detection circuit.Refer to that specifically current return through the electric energy measuring equipment that current transformer (CT) inserts, comprises the electricity load management terminal with electric energy metrical function.
Background technology
Electric energy measuring equipment is as the foundation of power department to power consumption statistics and charge, and its accuracy and reliability are very important.The electric energy of metering depends on the product of voltage, electric current, power factor three and time, changes above arbitrary key element, all can reach the purpose of stealing.The stealing of difference method is concluded and mainly contain voltage method stealing, current method stealing, the stealing of misphase method, expanded to existing electricity filching means.For voltage method stealing, the stealing of misphase method and the stealing of expansion difference method, all have the precautionary technology and the device of comparative maturity at present.And the current method stealing is a difficult point of anti-theft electricity technology always, for the electric energy measuring equipment that current return inserts through CT, some users by disconnect or short circuit CT once/the secondary side circuit, reach the purpose of stealing.Wherein especially with the most difficult strick precaution of fraudulent use electricity by short-circuit (stealing of U type), this stealing martingale is simple, and hidden-type is stronger, is easy to fast quick-recovery.At present, mainly rely on current method to detect,, then electricity filching behavior may take place if current anomaly reduces.This detection method accuracy rate is low, because the factor that causes electric current to reduce is a lot, therefore the situation of judging by accident, failing to judge happens occasionally, and has caused many negative effects for the work of power monitoring department.
Summary of the invention
The purpose of this utility model proposes a kind of anti-current method stealing real-time detection circuit exactly.Can detect the electricity filching behavior that occurs in the CT measurement loop quickly and accurately.And can discern concrete stealing mode, accurately distinguish CT once/secondary short circuit, CT once/four kinds of different electricity filching means such as second open circuit.
For achieving the above object, the technical solution adopted in the utility model is: it is made up of signal transmitting device (ST), impedance matching circuit, high-frequency oscillating circuits, signal processing circuit, microprocessor (MCU) and alternating current sampling circuit, and the secondary coil of signal transmitting device (ST) is serially connected in current transformer (CT) secondary circuit, the elementary high-frequency oscillating circuits that connects; Impedance matching circuit is composed in parallel by resistance (R) and electric capacity (C), forms (RLC) parallel circuit with signal transmitting device (ST) primary coil, current transformer (CT) secondary coil; High-frequency oscillating circuits is serially connected in the input end of signal transmitting device (ST) primary coil, and signal processing circuit is serially connected in the output terminal of signal transmitting device (ST) primary coil, the A/D conversion mouth of the output termination microprocessor (MCU) of signal processing circuit.
The utility model circuit structure is simple, volume is little, in light weight, can embed metering outfit inside easily, do not change the external interface of metering outfit, be user-friendly to.The signal transmitting device (ST) that is provided with is a special coupling transformer, effect with two aspects: the 1) isolation of realization strong and weak signals, under the normal condition, the CT secondary circuit will be by the power current signal of 5～7A, and oscillatory circuit is made up of low-power device, therefore will realize the isolation of strong and weak signals by ST; 2) impedance variation with the CT secondary circuit is reflected to signal processing circuit.
The effect that the impedance matching circuit that is provided with has two aspects.1) by coupling and ST primary coil and CT secondary coil composition RLC parallel circuit, and satisfies certain condition of resonance, in order to amplify the impedance variation of CT secondary circuit.2) for different CT, the inductance L ct of secondary coil has some differences, and this judgement to CT secondary side state does not have any influence; But when carrying out the judgement of CT primary side state, can make the detected signal of MCU produce certain drift.At this situation, the influence that can come the erasure signal drift to cause by the device parameters of adjusting match circuit.
The high-frequency oscillation signal that the high-frequency oscillating circuits that is provided with produces is after the ST decay, the entering signal treatment circuit carries out filtering, amplification and amplitude transformation, export to microprocessor MCU then, regularly inject A, B, C three-phase current loop by commutation circuit control detectable signal, and the high-frequency signal that signal processing circuit is exported is carried out A/D sample, and calculate its all square amplitude, judge in view of the above CT once/the current physical state of secondary circuit, accurately distinguish CT once/secondary short circuit, CT once/four kinds of different modes of connection such as second open circuit.
Description of drawings
Fig. 1 is an electrical block diagram of the present utility model;
Fig. 2 is the schematic diagram of the utility model match circuit;
Fig. 3 is the equivalent schematic diagram of the utility model match circuit.
Embodiment
The utility model will be further described below in conjunction with drawings and Examples:
Fig. 1 is the structural drawing of the utility model embodiment, comprises signal transmitting device ST, impedance matching circuit, high-frequency oscillating circuits, signal processing circuit, microprocessor MCU and alternating current sampling circuit.Signal transmitting device ST is actually a coupling transformer, and no-load voltage ratio K ≈ 1 secondary coil is serially connected in current transformer CT secondary circuit, the elementary high-frequency oscillating circuits that connects.For power frequency component, the impedance of signal transmitting device ST secondary coil is very little, and the caused pressure drop of the power current of flowing through is very little, and is also very little at the voltage signal of primary coil induction, thereby played the effect that strong and weak signals is isolated.For the high frequency detectable signal from the elementary injection of signal transmitting device ST, impedance situation more complicated will be analyzed according to current transformer CT secondary side different wiring situation and combined impedance match circuit.The secondary coil of signal transmitting device ST is serially connected in current transformer CT secondary circuit, the elementary high-frequency oscillating circuits that connects.
As shown in Figure 2, impedance matching circuit is composed in parallel by resistance R and capacitor C, forms the RLC parallel circuit with signal transmitting device ST primary coil and CT secondary coil.Principle of work is: Lst is the primary coil of signal transmitting device ST transformer, and Lct is the secondary coil of current transformer CT, and the load of ST transformer is composed in parallel by resistance R, capacitor C, Lct, and establishing its impedance is RL.According to the principle that ST load gained power before and after the equivalence equates circuit is carried out equivalent transformation, obtain the loaded impedance RL ' after the equivalence.When no-load voltage ratio K ≈ 1, before and after the equivalent transformation, loaded impedance RL remains unchanged substantially, and equivalent electrical circuit as shown in Figure 3.ST primary coil Lst and CT secondary coil Lct as can be seen, and the R of match circuit, C form the RLC parallel circuit jointly.CT once/the different wiring state of secondary, will cause equivalent electrical circuit input impedance Z as shown in Figure 3
InChange.When the CT second open circuit, the input impedance Z of equivalent electrical circuit
InReach maximal value; When CT secondary short circuit, input impedance Z
InMinimum.Input impedance Z
InDifference, the detectable signal mean square value V that MCU records
sAlso different, input impedance Z
InBig more, V
sBe worth more little; Otherwise, input impedance Z
InMore little, V
sBe worth big more.Pass through V
sBut Direct Recognition CT once/the current wiring state in secondary side loop.If V
S1, V
S2, V
S3, V
S4, V
S5Represent respectively that CT second short circuit, CT first short circuit, CT normally connect, CT once opens a way, during the CT second open circuit, the V that MUC records
sValue then has: V
S1＞V
S2＞V
S3＞V
S4＞V
S5Therefore, according to V
sValue, MCU can accurately discern CT once/secondary short circuit, CT once/four kinds of different modes of connection such as second open circuit.
High-frequency oscillating circuits, signal processing circuit are conventional circuit, high-frequency oscillating circuits is serially connected in the input end of signal transmitting device ST primary coil, signal processing circuit is serially connected in the output terminal of signal transmitting device ST primary coil, the A/D conversion mouth of the output termination microprocessor MCU of signal processing circuit.The high-frequency oscillation signal that high-frequency oscillating circuits produces is behind the ST primary coil, the entering signal treatment circuit carries out filtering, amplify and amplitude transformation, it is transformed to the amplitude transformation that suitable microprocessor MCU carries out the A/D sampling, export to MCU then, MCU regularly injects A by commutation circuit control detectable signal, B, C three-phase current loop, and the high-frequency signal that signal processing circuit is exported is carried out A/D sample, and calculate its all square amplitude, judge in view of the above CT once/the current physical state of secondary circuit, accurately distinguish CT once/the secondary short circuit, CT once/four kinds of different modes of connection such as second open circuit.
Claims (2)
1, a kind of anti-current method stealing real-time detection circuit, comprise alternating current sampling circuit and microprocessor (MCU), it is characterized in that: also be provided with signal transmitting device (ST), impedance matching circuit, high-frequency oscillating circuits and signal processing circuit, the secondary coil of signal transmitting device (ST) is serially connected in current transformer (CT) secondary circuit, the elementary high-frequency oscillating circuits that connects; Impedance matching circuit is composed in parallel by resistance (R) and electric capacity (C), forms (RLC) parallel circuit with signal transmitting device (ST) primary coil, current transformer (CT) secondary coil; High-frequency oscillating circuits is serially connected in the input end of signal transmitting device (ST) primary coil, and signal processing circuit is serially connected in the output terminal of signal transmitting device (ST) primary coil, the A/D conversion mouth of the output termination microprocessor (MCU) of signal processing circuit.
2, anti-current method stealing real-time detection circuit according to claim 1, it is characterized in that: described signal transmitting device (ST) is a coupling transformer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920088632U CN201373892Y (en) | 2009-02-23 | 2009-02-23 | Real-time detection circuit for preventing electricity-stealing in current method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200920088632U CN201373892Y (en) | 2009-02-23 | 2009-02-23 | Real-time detection circuit for preventing electricity-stealing in current method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201373892Y true CN201373892Y (en) | 2009-12-30 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200920088632U Expired - Fee Related CN201373892Y (en) | 2009-02-23 | 2009-02-23 | Real-time detection circuit for preventing electricity-stealing in current method |
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| CN (1) | CN201373892Y (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185823A (en) * | 2011-12-29 | 2013-07-03 | 北京普源精电科技有限公司 | Oscilloscope provided with frequency response compensating circuit |
| CN111693904A (en) * | 2020-04-29 | 2020-09-22 | 宁波三星医疗电气股份有限公司 | Terminal box access line sequence detection circuit and detection method using same |
-
2009
- 2009-02-23 CN CN200920088632U patent/CN201373892Y/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185823A (en) * | 2011-12-29 | 2013-07-03 | 北京普源精电科技有限公司 | Oscilloscope provided with frequency response compensating circuit |
| CN111693904A (en) * | 2020-04-29 | 2020-09-22 | 宁波三星医疗电气股份有限公司 | Terminal box access line sequence detection circuit and detection method using same |
| CN111693904B (en) * | 2020-04-29 | 2022-07-29 | 宁波三星医疗电气股份有限公司 | Terminal box access line sequence detection circuit and detection method using same |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20091230 Termination date: 20130223 |