CN205049679U - Residual current transformer sampling circuit - Google Patents
Residual current transformer sampling circuit Download PDFInfo
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- CN205049679U CN205049679U CN201520713273.0U CN201520713273U CN205049679U CN 205049679 U CN205049679 U CN 205049679U CN 201520713273 U CN201520713273 U CN 201520713273U CN 205049679 U CN205049679 U CN 205049679U
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Abstract
The utility model discloses a residual current transformer sampling circuit for sample and the signal sampling module handled, be used for sampling the differential signal operation that voltage signal that the module gathered enlargies output with the signal and enlarge the module, be used for providing standard reference voltage's reference voltage module and CPU processing module residual current transformer's output signal, the input of signal sampling module is connected with residual current transformer's output, the output of signal sampling module and the output of reference voltage module respectively with the differential signal operation is enlargied the input of module and is connected, the output lug connection CPU processing module's of module AD conversion port is enlargied in the differential signal operation. This sampling circuit measurement accuracy is high, and the connecting wire state between residual current transformer and the sampling circuit can accurately be differentiated to the dependable performance, satisfies on -the -spot user's demand.
Description
Technical field
The utility model relates to circuit field, particularly relates to a kind of residual current transformer sample circuit.
Background technology
The connection of current detector for electric fire protection and residual current transformer, all directly a sampling resistor in parallel for the output terminal of residual current transformer, the input end of A/D convertor circuit is directly received after current signal being converted to voltage signal, when there being electric current to flow through in residual current transformer, A/D convertor circuit directly send CPU to calculate sampled data, and detector just can obtain the electric current that residual current transformer flows through.But this mode has individual shortcoming, when the residual current of residual current transformer is 0, then detector display electric current is also 0, detector can be judged as that the electric current flow through is 0, erroneous judgement is there will be when the connection status short circuit namely between residual current transformer and sampling resistor or open circuit fault, cause judging that residual current transformer be the electric current that connecting line short circuit or open circuit cause flowing through mutual inductor is zero, lose the function for monitoring to residual current transformer.
Utility model content
The purpose of this utility model is to propose a kind of residual current transformer sample circuit, when CPU processing module detects that residual electricity flow valuve is zero, the standard voltage value that magnitude of voltage and reference voltage module that signal sampling module exports provide exports CPU processing module to by differential signal operation amplifier module, the DC voltage value collected by CPU processing module to judge between residual current transformer and sampling resistor connecting line be normally, short circuit or open circuit fault.
In order to achieve the above object, the technical scheme that adopts of the utility model is as follows:
A kind of residual current transformer sample circuit, comprising: for the output signal of residual current transformer is sampled and signal sampling module process, for by signal sampling module acquires to voltage signal amplify the differential signal operation amplifier module of output, the reference voltage module being used for providing canonical reference voltage and CPU processing module; The described input end of signal sampling module is connected with the output terminal of residual current transformer, the output terminal of described signal sampling module and the output terminal of reference voltage module are connected with the input end of described differential signal operation amplifier module respectively, and the output terminal of described differential signal operation amplifier module directly connects the A/D conversion port of CPU processing module.
Concrete, described signal sampling module is made up of sampling resistor R1, resistance R2, resistance R3; Described differential signal operation amplifier module is made up of resistance R4, resistance R5, resistance R6, resistance R7, operational amplifier U1; Described reference voltage module is made up of an external reference voltages;
Concrete, described signal sampling module is connected in series by sampling resistor R1 and resistance R2, resistance R3, and described sampling resistor R1 is connected across between the output terminal of residual current transformer;
Concrete, the output terminal of described signal sampling module is also connected respectively by the inverting input of resistance R4, resistance R6 and the operational amplifier U1 of described signal operation amplification module, normal phase input end;
Concrete, the output terminal of described operational amplifier U1 directly connects the A/D conversion port of described CPU processing module, and the output terminal of described operational amplifier U1 is also connected to the inverting input of operational amplifier U1 by resistance R5;
Concrete, one end of the resistance R7 of described differential signal operation amplifier module connects external reference voltages, and the other end is connected with the normal phase input end of operational amplifier U1.
Preferably, described operational amplifier U1 adopts operational amplifier LM2904M.
In sum, the utility model has following beneficial effect: between residual current transformer and CPU processing module, increase by a sample circuit, when CPU processing module receives the output voltage of sample circuit and the residual current calculated is zero, the magnitude of voltage that signal sampling module acquires exports, the normal voltage that reference voltage module exports exports CPU processing module to through the operational amplifier U1 of differential signal operation amplifier module, the DC voltage value collected by CPU processing module is come relatively and judges that residual current transformer connecting line is normal, short circuit or open circuit fault.This sample circuit measuring accuracy is high, dependable performance, accurately can differentiate the connection status between residual current transformer and sample circuit, meet the demand of onsite user.
Accompanying drawing explanation
Fig. 1 is the residual current transformer sample circuit theory structure schematic diagram of the utility model preferred embodiment.
Fig. 2 is the residual current transformer sample circuit structural representation of the utility model preferred embodiment.
Embodiment
In order to allow those skilled in the art can understand the technical solution of the utility model better, below in conjunction with accompanying drawing and embodiment, the utility model is further elaborated.
As shown in Figure 1, a kind of residual current transformer sample circuit that the utility model embodiment provides, comprise for the output signal of residual current transformer is sampled and the signal sampling module processed, for by signal sampling module acquires to voltage signal amplify export differential signal operation amplifier module, the reference voltage module being used for providing canonical reference voltage and CPU processing module; The input end of signal sampling module is connected with the output terminal of residual current transformer, the output terminal of signal sampling module and the output terminal of reference voltage module are connected with the input end of differential signal operation amplifier module respectively, and the output terminal of differential signal operation amplifier module directly connects the A/D conversion port of CPU processing module.
As shown in Figure 2, in the present embodiment, signal sampling module is made up of sampling resistor R1, resistance R2, resistance R3; Differential signal operation amplifier module is made up of resistance R4, resistance R5, resistance R6, resistance R7, operational amplifier U1; Described reference voltage module is made up of an external reference voltages; Signal sampling module is connected in series by sampling resistor R1 and resistance R2, resistance R3, and sampling resistor R1 is connected across between the output terminal of residual current transformer; The output terminal of signal sampling module is also connected respectively by the inverting input of resistance R4, resistance R6 and the operational amplifier U1 of differential signal operation amplifier module, normal phase input end; The output terminal of operational amplifier U1 directly connects the A/D conversion port of CPU processing module, and the output terminal of operational amplifier U1 is also connected to the inverting input of operational amplifier U1 by resistance R5; One end of the resistance R7 of differential signal operation amplifier module connects external reference voltages, and the other end is connected with the normal phase input end of operational amplifier U1.
In the present embodiment, operational amplifier U1 adopts operational amplifier LM2904M.
The principle of work of the present embodiment is as follows: when normally working, sampling resistor R1 is in parallel with residual current transformer, residual current signal is converted to voltage signal through sampling resistor R1, the standard voltage signal that this voltage signal and reference voltage module export enters A/D conversion port to CPU processing module through the operational amplifier U1 of differential signal operation amplifier module, CPU processing module differentiates the voltage swing that operational amplifier exports, and realizes normal residual current function for monitoring.
Concrete, when the output voltage of the sample circuit that CPU processing module receives and the residual current calculated is zero time, just need to carry out fault detect to residual current transformer connecting line, judgement be due to residual current transformer and sampling resistor R1 connecting line short circuit or open circuit causes sample rate current to be 0, if during the connecting line short circuit of residual current transformer and sampling resistor R1, DC internal resistance is very little, time in parallel with sampling resistor R1, resistance is close to 0, the DC voltage received when then the DirectCurrent Voltage Ratio connecting line that receives of CPU processing module is normal is large, the connecting line short circuit of residual current transformer and sampling resistor R1 can be judged and make corresponding prompting, if during the connecting line open circuit of residual current transformer and sampling resistor R1, infinite, after in parallel with sampling resistor R1, internal resistance is negligible, resistance in parallel is close to the resistance of R1, enter A/D conversion port through the operational amplifier U1 of differential signal amplification module, the DC voltage received when now the DirectCurrent Voltage Ratio connecting line that receives of CPU processing module is normal is little, can judge the connecting line open circuit of residual current transformer and sampling resistor R1 and make corresponding prompting.
The present embodiment has following advantage:
1. circuit design is reasonable and with low cost;
2. measuring accuracy is high, dependable performance, accurately can differentiate the connection status of the connecting line between residual current transformer and sample circuit.
The present embodiment is more excellent embodiment of the present utility model, and the part be not described in detail all adopts known mature technology.It should be noted that; when not deviating from the utility model spirit and essence thereof; those of ordinary skill in the art are when making various corresponding change and distortion according to the utility model, but these change and are out of shape the protection domain that all should belong to the claim appended by the utility model.
Claims (3)
1. a residual current transformer sample circuit, is characterized in that, comprising:
For the output signal of residual current transformer is sampled and the signal sampling module processed, for by signal sampling module acquires to voltage signal amplify export differential signal operation amplifier module, the reference voltage module being used for providing canonical reference voltage and CPU processing module; The described input end of signal sampling module is connected with the output terminal of residual current transformer, the output terminal of described signal sampling module and the output terminal of reference voltage module are connected with the input end of described differential signal operation amplifier module respectively, and the output terminal of described differential signal operation amplifier module directly connects the A/D conversion port of CPU processing module.
2. a kind of residual current transformer sample circuit according to claim 1, is characterized in that, described signal sampling module is made up of sampling resistor R1, resistance R2, resistance R3; Described differential signal operation amplifier module is made up of resistance R4, resistance R5, resistance R6, resistance R7, operational amplifier U1; Described reference voltage module is made up of an external reference voltages;
Described signal sampling module is connected in series by sampling resistor R1 and resistance R2, resistance R3,
Described sampling resistor R1 is connected across between the output terminal of residual current transformer;
The output terminal of described signal sampling module is also connected respectively by the inverting input of resistance R4, resistance R6 and the operational amplifier U1 of described signal operation amplification module, normal phase input end;
The output terminal of described operational amplifier U1 directly connects the A/D conversion port of described CPU processing module, and the output terminal of described operational amplifier U1 is also connected to the inverting input of operational amplifier U1 by resistance R5;
One end of the resistance R7 of described differential signal operation amplifier module connects external reference voltages, and the other end is connected with the normal phase input end of operational amplifier U1.
3. a kind of residual current transformer sample circuit according to claim 2, is characterized in that, described operational amplifier U1 adopts operational amplifier LM2904M.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520713273.0U CN205049679U (en) | 2015-09-15 | 2015-09-15 | Residual current transformer sampling circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520713273.0U CN205049679U (en) | 2015-09-15 | 2015-09-15 | Residual current transformer sampling circuit |
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| CN205049679U true CN205049679U (en) | 2016-02-24 |
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| CN201520713273.0U Active CN205049679U (en) | 2015-09-15 | 2015-09-15 | Residual current transformer sampling circuit |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137268A (en) * | 2015-09-15 | 2015-12-09 | 广州智光自动化有限公司 | Sampling circuit for residual current transformer |
| CN106160071A (en) * | 2016-06-29 | 2016-11-23 | 安徽锐能科技有限公司 | Short-circuit protection circuit |
| CN108535680A (en) * | 2018-03-30 | 2018-09-14 | 上海电机学院 | Residual current transformer fault self-diagnosis system and method |
| CN111551770A (en) * | 2019-02-12 | 2020-08-18 | 恩智浦有限公司 | Current monitoring device |
-
2015
- 2015-09-15 CN CN201520713273.0U patent/CN205049679U/en active Active
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105137268A (en) * | 2015-09-15 | 2015-12-09 | 广州智光自动化有限公司 | Sampling circuit for residual current transformer |
| CN106160071A (en) * | 2016-06-29 | 2016-11-23 | 安徽锐能科技有限公司 | Short-circuit protection circuit |
| CN106160071B (en) * | 2016-06-29 | 2019-05-07 | 安徽锐能科技有限公司 | Short-circuit protection circuit |
| CN108535680A (en) * | 2018-03-30 | 2018-09-14 | 上海电机学院 | Residual current transformer fault self-diagnosis system and method |
| CN108535680B (en) * | 2018-03-30 | 2020-04-14 | 上海电机学院 | Fault self-diagnosis system and method for residual current transformer |
| CN111551770A (en) * | 2019-02-12 | 2020-08-18 | 恩智浦有限公司 | Current monitoring device |
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