CN113721180A - Detection circuit and detection method for residual current transformer - Google Patents
Detection circuit and detection method for residual current transformer Download PDFInfo
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- CN113721180A CN113721180A CN202110677987.0A CN202110677987A CN113721180A CN 113721180 A CN113721180 A CN 113721180A CN 202110677987 A CN202110677987 A CN 202110677987A CN 113721180 A CN113721180 A CN 113721180A
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- 238000005070 sampling Methods 0.000 claims abstract description 50
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- 238000012545 processing Methods 0.000 claims abstract description 7
- 230000002159 abnormal effect Effects 0.000 claims description 6
- 230000005540 biological transmission Effects 0.000 claims description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
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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
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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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
- G01R31/54—Testing for continuity
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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
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Abstract
The invention aims to provide a detection circuit and a detection method of a residual current transformer, which can detect whether the characteristics of turn-to-turn short circuit, open circuit and the like exist in the transformer or not, and comprises an N-channel MOS tube and a CPU (central processing unit), wherein the drain electrode of the MOS tube is connected with positive voltage, the grid electrode of the MOS tube is connected with a control pin of the CPU through a resistor R1, one end of the transformer is connected with the source electrode of the MOS tube and is connected with a first AD sampling pin of the CPU through a resistor R2, the other end of the transformer is connected with a second AD sampling pin of the CPU through a resistor R3, the transformer consists of a magnetic ring and a coil wound on the magnetic ring according to the inside of the transformer, when the current flowing through the coil changes, the transformer can show the characteristic of inductance, a pulse method is adopted to apply pulses to the transformer, then a group of data is obtained by carrying out staggered average method conversion on the pulse data, and then the short circuit and open circuit faults of the transformer are judged according to the slope of the group of data, the judgment accuracy is higher and the cost is lower.
Description
Technical Field
The invention belongs to the technical field of mutual inductor detection, and particularly relates to a detection circuit and a detection method for a residual current mutual inductor.
Background
At present, the development of electrical fire monitoring technology drives a great deal of application of electrical fire monitoring detectors. The residual current type electrical fire monitoring detector is one of the largest used amount in the field of electrical fire monitoring and detecting. The residual current transformer (hereinafter referred to as transformer) is a key component, and whether the characteristic of the residual current transformer is normal or not directly determines the reliability and accuracy of the detector. In all detector applications, a function of detecting and judging whether the characteristics of the mutual inductor are normal or not is required. The traditional detection method is to add an additional circuit on a loop to measure the resistance value of the sensor, and judge whether the internal short circuit and open circuit of the transformer exist or not by judging whether the resistance value of the sensor is in a normal range or not. However, this method has a certain limitation that the judgment result is not reliable. The reason is that the internal resistances of different transformers are different in size, and even if the transformers of the same specification and model have different individual differences of the internal resistances, uncertainty is brought to judging whether the characteristics of the transformers are normal or not by judging the sizes of the resistances. In order to be compatible with the resistance value difference, the judged resistance value range can only be widened, so that when a slight turn-to-turn short circuit phenomenon exists in the transformer, the performance of the transformer is influenced, but the change of the internal resistance value is very small, whether the performance of the transformer is normal or not can not be accurately judged by a resistance measurement method, and the defect of the detection method is revealed.
Disclosure of Invention
The invention aims to provide a detection circuit and a detection method for a residual current transformer, which can detect whether characteristics such as turn-to-turn short circuit and open circuit exist in the transformer.
The technical scheme for solving the technical problems of the invention is as follows: the utility model provides a residual current transformer detection circuitry, includes N channel type MOS pipe, CPU, the drain electrode of MOS pipe connects the positive voltage, the gate of MOS pipe is connected with CPU's control pin through resistance R1, the one end of mutual-inductor is connected with the source electrode of MOS pipe and is connected with CPU's first AD sampling pin through resistance R2, the other end of mutual-inductor passes through resistance R3 and is connected with CPU's second AD sampling pin, CPU's control pin is used for sending the level to the gate of MOS pipe, CPU's first AD sampling pin, first AD sampling pin are used for measuring the voltage signal at mutual-inductor both ends.
A detection method of a residual current transformer detection circuit is characterized by comprising the following steps: the method comprises the following steps:
s1: when no external alternating voltage signal is transmitted into the mutual inductor, no voltage signal is generated on the mutual inductor, the CPU cannot acquire the voltage signal, the CPU applies a high level through the control pin at the moment, the control grid of the MOS tube is influenced by the high level, the drain electrode of the MOS tube is conducted with the source electrode, the positive voltage on the drain electrode of the MOS tube is applied to one end of the mutual inductor through the source electrode, and voltage drop is generated on one end and the other end of the mutual inductor;
s2: acquiring and processing voltage signal data between a first AD sampling pin of a CPU and a second AD sampling pin of the CPU;
s3: when the voltage signal data do not change from low to high or change fluctuation is smaller compared with normal data collected by the first AD sampling pin and the second AD sampling pin when an alternating current voltage signal is transmitted into the mutual inductor from the outside, the internal short circuit of the mutual inductor is judged;
and when the voltage signal data are not changed and the voltage signal value is lower than that of normal data acquired by the first AD sampling pin and the second AD sampling pin when an alternating current voltage signal is transmitted into the mutual inductor from the outside, judging that the mutual inductor is disconnected.
The width of the CPU applying a high-level transmission pulse through the control pin in the step S1 is between 8 msec and 10 msec.
In the step S2, after the delay time of 0.5 ms from the start time of applying a high level to the control pin of the CPU for collecting the voltage signal data is needed, the second AD sampling pin of the CPU starts collecting the voltage signal, and the sampling interval for collecting the voltage signal is 0.2 ms.
The sampling points for collecting the voltage signals are 33 points, namely d1, d2, d3, d4, d5,. d31, d32 and d 33; the total sampling duration is 6.4 milliseconds.
The processing procedure of the data in step S2 specifically includes: the first 2 values are rounded off and used starting from the 3 rd value, i.e.: d3, d4, d 5.. d25, d26, d27, then calculated as the rule of the staggered average method:
firstly, calculating the average value of the previous continuous 4 values, (D3+ D4+ D5+ D6) ÷ 4 ═ D1;
calculating the average value of 4 continuous numerical values from the 6 th numerical value, (D6+ D7+ D8+ D9) ÷ 4 ═ D2;
calculating the average value of 4 continuous numerical values from the 9 th numerical value, (D9+ D10+ D11+ D12) ÷ 4 ═ D3;
…
calculating the average value of 4 continuous numerical values from the 24 th numerical value, (D24+ D25+ D26+ D27) ÷ 4 ═ D8;
4 slopes were calculated piecewise: k1, k2, k3, k 4;
tanα(D5-D1)＝k1,tanα(D6-D2)＝k2,tanα(D7-D3)＝k3, tanα(D8-D4)＝k4。
the determination process of the processed data in step S3 specifically includes: if s2< k1< s1, s2< k2< s1, s2< k3< s1, and s2< k4< s1, namely 4 slope values of k1, k2, k3 and k4 are all in a specified range, judging that the transformer parameters are normal; if the 4 slope values of k1, k2, k3 and k4 are not in the specified range, judging that the transformer parameters are abnormal; where s1 is the allowable positive error range value and s2 is the allowable negative error range value.
When the mutual inductor is judged to be abnormal, further judgment is carried out; if the four values of D1, D2, D3 and D4 are all approximately equal to 0, namely the value of the voltage signal acquired by the second AD sampling pin of the CPU is approximately equal to 0, the mutual inductor is judged to be open-circuited; in another case, (D5-D1) ═ L1, (D6-D2) ═ L2, (D7-D3) ═ L3, (D8-D4) ═ L4, if L1 ≈ 0, L2 ≈ 0, L3 ≈ 0, and L4 ≈ 0, that is, the voltage signal value collected by the second AD sampling pin of the CPU is not equal to 0, and the fluctuation of the collected voltage signal value is smaller than that in the normal case, it is determined that the transformer is short-circuited.
The invention has the beneficial effects that: according to the technical scheme, the mutual inductor is composed of a magnetic ring and a coil wound on the magnetic ring, when current flowing through the coil changes, the mutual inductor can show the characteristic of inductance characteristic, a pulse method is adopted to apply pulses to the mutual inductor, then the pulse data are converted by a staggered average method to obtain a group of data, and then the short circuit and open circuit faults of the mutual inductor are judged according to the slope of the group of data, so that the judgment accuracy is high, and the cost is low.
Drawings
Fig. 1 is a circuit schematic of the present invention.
FIG. 2 is a waveform diagram measured when the CPU of the present invention applies a high level through the control pin.
FIG. 3 is a waveform illustrating the voltage signal data without a low-to-high change in accordance with the present invention.
FIG. 4 is a waveform diagram of the present invention when the voltage signal data is unchanged and the voltage signal value is low.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a residual current transformer detection circuit includes an N-channel type MOS transistor and a CPU, wherein a drain of the MOS transistor is connected to a positive voltage, a gate of the MOS transistor is connected to a control pin of the CPU through a resistor R1, one end of the transformer is connected to a source of the MOS transistor and is connected to a first AD sampling pin of the CPU through a resistor R2, the other end of the transformer is connected to a second AD sampling pin of the CPU through a resistor R3, the control pin of the CPU is used for sending a level to the gate of the MOS transistor, and the first AD sampling pin of the CPU are used for measuring voltage signals at two ends of the transformer.
A detection method of a residual current transformer detection circuit is characterized by comprising the following steps: the method comprises the following steps:
s1: when no external alternating voltage signal is transmitted into the mutual inductor, no voltage signal is generated on the mutual inductor, the CPU cannot acquire the voltage signal, the CPU applies a high level through the control pin at the moment, the control grid of the MOS tube is influenced by the high level, the drain electrode of the MOS tube is conducted with the source electrode, the positive voltage on the drain electrode of the MOS tube is applied to one end of the mutual inductor through the source electrode, and voltage drop is generated on one end and the other end of the mutual inductor; at this moment, because the coil of the mutual inductor has the characteristic of inductance, namely when the voltage applied to the two ends of the coil suddenly changes, the coil can prevent the voltage from changing, the voltage on the other end of the mutual inductor can slowly change, the measured other end of the mutual inductor can generate a waveform as shown in fig. 2, and a group of voltage signal data is collected on a second AD sampling pin of the CPU.
S2: acquiring and processing voltage signal data between a first AD sampling pin of a CPU and a second AD sampling pin of the CPU;
s3: as shown in fig. 3, when the voltage signal data does not change from low to high or becomes significantly smaller (the fluctuation of the voltage signal data is smaller than that of normal data acquired by the first AD sampling pin and the second AD sampling pin when an ac voltage signal is transmitted into the transformer from the outside), it is determined that a short circuit occurs inside the transformer, because the inductance of the transformer coil is significantly reduced when the short circuit occurs inside the transformer;
as shown in fig. 4, when the voltage signal data is not changed and the voltage signal value is low (compared with the normal data collected by the first AD sampling pin and the second AD sampling pin when an external ac voltage signal is introduced into the transformer, the voltage signal value is lower), the transformer is determined to be open, because when the transformer is internally open-circuited, the inductance of the mutual inductor does not exist.
In step S1, the width of the high-level transmission pulse applied by the CPU through the control pin is between 8 ms and 10 ms, and after the time is too long, the change of the waveform does not exist, and the acquired data has no use value.
In the step S2, after the delay time of 0.5 ms from the start time of applying a high level to the control pin of the CPU for collecting the voltage signal data is needed, the second AD sampling pin of the CPU starts collecting the voltage signal, and the sampling interval for collecting the voltage signal is 0.2 ms.
The sampling points for collecting the voltage signals are 33 points, namely d1, d2, d3, d4, d5,. d31, d32 and d 33; the total sampling duration is 6.4 milliseconds.
The processing procedure of the data in step S2 specifically includes: the first 2 values are rounded off and used starting from the 3 rd value, i.e.: d3, d4, d 5.. d25, d26, d27, then calculated as the rule of the staggered average method:
firstly, calculating the average value of the previous continuous 4 values, (D3+ D4+ D5+ D6) ÷ 4 ═ D1;
calculating the average value of 4 continuous numerical values from the 6 th numerical value, (D6+ D7+ D8+ D9) ÷ 4 ═ D2;
calculating the average value of 4 continuous numerical values from the 9 th numerical value, (D9+ D10+ D11+ D12) ÷ 4 ═ D3;
…
calculating the average value of 4 continuous numerical values from the 24 th numerical value, (D24+ D25+ D26+ D27) ÷ 4 ═ D8;
4 slopes were calculated piecewise: k1, k2, k3, k 4;
tanα(D5-D1)＝k1,tanα(D6-D2)＝k2,tanα(D7-D3)＝k3, tanα(D8-D4)＝k4。
the determination process of the processed data in step S3 specifically includes: if s2< k1< s1, s2< k2< s1, s2< k3< s1, and s2< k4< s1, namely 4 slope values of k1, k2, k3 and k4 are all in a specified range, judging that the transformer parameters are normal; if the 4 slope values of k1, k2, k3 and k4 are not in the specified range, judging that the transformer parameters are abnormal; where s1 is the allowable positive error range value and s2 is the allowable negative error range value.
When the mutual inductor is judged to be abnormal, further judgment is carried out; if the four values of D1, D2, D3 and D4 are all approximately equal to 0, namely the value of the voltage signal acquired by the second AD sampling pin of the CPU is approximately equal to 0, the mutual inductor is judged to be open-circuited; in another case, (D5-D1) ═ L1, (D6-D2) ═ L2, (D7-D3) ═ L3, (D8-D4) ═ L4, if L1 ≈ 0, L2 ≈ 0, L3 ≈ 0, and L4 ≈ 0, that is, the voltage signal value acquired by the second AD sampling pin of the CPU is not equal to 0 and is almost equal (the fluctuation of the acquired voltage signal value is smaller than that in the normal case), it is determined that the transformer is short-circuited.
According to the invention, the mutual inductor is composed of the magnetic ring and the coil wound on the magnetic ring, when the current flowing through the coil changes, the mutual inductor can show the characteristic of inductance characteristic, a pulse method is adopted to apply pulses to the mutual inductor, then the pulse data is converted by a staggered average method to obtain a group of data, and then the short circuit and open circuit faults of the mutual inductor are judged according to the slope of the group of data, so that the judgment accuracy is higher and the cost is lower.
Claims (8)
1. A residual current transformer detection circuit is characterized in that: including N channel type MOS pipe, CPU, the drain electrode of MOS pipe connects the positive voltage, the gate of MOS pipe is connected with CPU's control pin through resistance R1, the one end of mutual-inductor is connected with the source electrode of MOS pipe and is connected with CPU's first AD sampling pin through resistance R2, the other end of mutual-inductor passes through resistance R3 and is connected with CPU's second AD sampling pin, CPU's control pin is used for sending the level to the gate of MOS pipe, CPU's first AD sampling pin, first AD sampling pin are used for measuring the voltage signal at mutual-inductor both ends.
2. A method of testing a residual current transformer test circuit as claimed in claim 1, wherein: the method comprises the following steps:
s1: when no external alternating voltage signal is transmitted into the mutual inductor, no voltage signal is generated on the mutual inductor, the CPU cannot acquire the voltage signal, the CPU applies a high level through the control pin at the moment, the control grid of the MOS tube is influenced by the high level, the drain electrode of the MOS tube is conducted with the source electrode, the positive voltage on the drain electrode of the MOS tube is applied to one end of the mutual inductor through the source electrode, and voltage drop is generated on one end and the other end of the mutual inductor;
s2: acquiring and processing voltage signal data between a first AD sampling pin of a CPU and a second AD sampling pin of the CPU;
s3: when the voltage signal data do not change from low to high or change fluctuation is smaller compared with normal data collected by the first AD sampling pin and the second AD sampling pin when an alternating current voltage signal is transmitted into the mutual inductor from the outside, the internal short circuit of the mutual inductor is judged;
and when the voltage signal data are not changed and the voltage signal value is lower than that of normal data acquired by the first AD sampling pin and the second AD sampling pin when an alternating current voltage signal is transmitted into the mutual inductor from the outside, judging that the mutual inductor is disconnected.
3. The method for detecting the residual current transformer as claimed in claim 2, wherein: the width of the CPU applying a high-level transmission pulse through the control pin in the step S1 is between 8 msec and 10 msec.
4. The method for detecting the residual current transformer as claimed in claim 3, wherein: in the step S2, after the delay time of 0.5 ms from the start time of applying a high level to the control pin of the CPU for collecting the voltage signal data is needed, the second AD sampling pin of the CPU starts collecting the voltage signal, and the sampling interval for collecting the voltage signal is 0.2 ms.
5. The method for detecting the residual current transformer as claimed in claim 4, wherein: the sampling points for collecting the voltage signals are 33 points, namely d1, d2, d3, d4, d5,. d31, d32 and d 33; the total sampling duration is 6.4 milliseconds.
6. The method for detecting the residual current transformer as claimed in claim 5, wherein: the processing procedure of the data in step S2 specifically includes: the first 2 values are rounded off and used starting from the 3 rd value, i.e.: d3, d4, d 5.. d25, d26, d27, then calculated as the rule of the staggered average method: firstly, calculating the average value of the previous continuous 4 values, (D3+ D4+ D5+ D6) ÷ 4 ═ D1;
calculating the average value of 4 continuous numerical values from the 6 th numerical value, (D6+ D7+ D8+ D9) ÷ 4 ═ D2;
calculating the average value of 4 continuous numerical values from the 9 th numerical value, (D9+ D10+ D11+ D12) ÷ 4 ═ D3;
…
calculating the average value of 4 continuous numerical values from the 24 th numerical value, (D24+ D25+ D26+ D27) ÷ 4 ═ D8;
4 slopes were calculated piecewise: k1, k2, k3, k 4;
tanα(D5-D1)＝k1,tanα(D6-D2)＝k2,tanα(D7-D3)＝k3,tanα(D8-D4)＝k4。
7. the method for detecting the residual current transformer as claimed in claim 6, wherein: the determination process of the processed data in step S3 specifically includes: if s2< k1< s1, s2< k2< s1, s2< k3< s1, and s2< k4< s1, namely 4 slope values of k1, k2, k3 and k4 are all in a specified range, judging that the transformer parameters are normal; if the 4 slope values of k1, k2, k3 and k4 are not in the specified range, judging that the transformer parameters are abnormal; where s1 is the allowable positive error range value and s2 is the allowable negative error range value.
8. The method for detecting the residual current transformer as claimed in claim 7, wherein: when the mutual inductor is judged to be abnormal, further judgment is carried out; if the four values of D1, D2, D3 and D4 are all approximately equal to 0, namely the value of the voltage signal acquired by the second AD sampling pin of the CPU is approximately equal to 0, the mutual inductor is judged to be open-circuited; in another case, (D5-D1) ═ L1, (D6-D2) ═ L2, (D7-D3) ═ L3, (D8-D4) ═ L4, if L1 ≈ 0, L2 ≈ 0, L3 ≈ 0, and L4 ≈ 0, that is, the voltage signal value collected by the second AD sampling pin of the CPU is not equal to 0, and the fluctuation of the collected voltage signal value is smaller than that in the normal case, it is determined that the transformer is short-circuited.
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| CN202110677987.0A CN113721180A (en) | 2021-06-18 | 2021-06-18 | Detection circuit and detection method for residual current transformer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117388562A (en) * | 2023-12-11 | 2024-01-12 | 珅斯电子(上海)有限公司 | Variable magneto-inductive current sensor and calibration method thereof |
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| CN105486971A (en) * | 2015-11-13 | 2016-04-13 | 浙江涵普电力科技有限公司 | Short circuit and open circuit state detection circuit for secondary side winding of current transformer |
| CN106291226A (en) * | 2016-07-27 | 2017-01-04 | 北大青鸟环宇消防设备股份有限公司 | Residual current transformer failure detector circuit and electrical fire-detector |
| CN110794332A (en) * | 2019-11-14 | 2020-02-14 | 浙江晨泰科技股份有限公司 | Residual current transformer detection system for fire detection detector and detection method thereof |
| CN213067672U (en) * | 2020-09-21 | 2021-04-27 | 河南力安测控科技有限公司 | Coil type sensor detection device |
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2021
- 2021-06-18 CN CN202110677987.0A patent/CN113721180A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105486971A (en) * | 2015-11-13 | 2016-04-13 | 浙江涵普电力科技有限公司 | Short circuit and open circuit state detection circuit for secondary side winding of current transformer |
| CN106291226A (en) * | 2016-07-27 | 2017-01-04 | 北大青鸟环宇消防设备股份有限公司 | Residual current transformer failure detector circuit and electrical fire-detector |
| CN110794332A (en) * | 2019-11-14 | 2020-02-14 | 浙江晨泰科技股份有限公司 | Residual current transformer detection system for fire detection detector and detection method thereof |
| CN213067672U (en) * | 2020-09-21 | 2021-04-27 | 河南力安测控科技有限公司 | Coil type sensor detection device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117388562A (en) * | 2023-12-11 | 2024-01-12 | 珅斯电子(上海)有限公司 | Variable magneto-inductive current sensor and calibration method thereof |
| CN117388562B (en) * | 2023-12-11 | 2024-03-12 | 珅斯电子(上海)有限公司 | Variable magneto-inductive current sensor and calibration method thereof |
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