CN104793100A - Detection device for circuit breakage and short circuit of secondary coil of electric leakage mutual inductor - Google Patents
Detection device for circuit breakage and short circuit of secondary coil of electric leakage mutual inductor Download PDFInfo
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- CN104793100A CN104793100A CN201510241863.2A CN201510241863A CN104793100A CN 104793100 A CN104793100 A CN 104793100A CN 201510241863 A CN201510241863 A CN 201510241863A CN 104793100 A CN104793100 A CN 104793100A
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Abstract
The invention discloses a detection device for circuit breakage and short circuit of a secondary coil of an electric leakage mutual inductor. The detection device comprises a residual current signal detection module, an operational amplifier module and a main control module, wherein the residual current signal detection module is used for detecting the operational amplifier module; the operational amplifier module is connected with the main control module; a sampling resistor in the residual current signal detection module is adopted to sample a present value of a direct-current voltage component according to the Ohm's law; the operational amplifier module is used for amplifying the direct-current voltage component; the main control module is used for judging the present state of the secondary coil of the leaking mutual inductor by calculating the amplified value of the direct-current voltage component; the sampling resistor in the residual current signal detection module is used for converting present alternative-current of the leaking mutual inductor into an alternative-current voltage component; the operational amplifier module is used for amplifying the alternative-current component; the main control module is used for calculating an external residual current value according to the alternative-current component and the resistance of the sampling resistor R1. By adopting the detection device, the circuit breakage and short circuit faults of the secondary coil of the leaking mutual inductor can be easily and effectively detected, and the external residual current value can be normally measured.
Description
Technical field
The present invention relates to the detection technique field of electric fire monitoring system, the pick-up unit of the open circuit of especially a kind of creepage mutual inductor secondary coil and short circuit.
Background technology
Creepage mutual inductor is the vitals in electric system.When broken string occurs creepage mutual inductor, very high induced voltage can be produced and equipment and the person are all damaged.Therefore, Timeliness coverage creepage mutual inductor is often needed to break so that relay protection device takes safeguard measure.For creepage mutual inductor secondary coil burn out detection, wire break detection method conventional at present has two kinds: one increases a measure loop by extra in creepage mutual inductor primary circuit, this loop is through the inductive coil of creepage mutual inductor, artificial applying current change quantity, secondary circuit induction current can be caused, by detecting secondary induction current with or without judging whether secondary breaks; Another kind increases in circuit to load burn out detection current module, applying Weak current, judging whether creepage mutual inductor secondary coil breaks by detecting this electric current in secondary coil.Although a kind of front method can detect broken string, when creepage mutual inductor rated current is very large time, want when secondary detection is to reliable electric current, the artificial electric current applied is just very large, adds cost and the complicacy of system; A kind of rear method then needs to increase in secondary coil loop to load burn out detection current module, although reduce the cost of system to a certain extent, but do not reduce the complexity of whole system, extra loading burn out detection current module also means the reliability and produceability that reduce whole system.And above two kinds of methods all can only detect creepage mutual inductor and whether are in broken string state, whether short-circuit condition is in for creepage mutual inductor and then cannot accurately detects, also have no idea to measure external redundant current value while detection creepage mutual inductor current state.
Summary of the invention
The pick-up unit of a kind of creepage mutual inductor secondary coil open circuit and the short circuit provided for the deficiencies in the prior art is provided, this device without the need to increasing extra detection current module in the primary winding or secondary coil loop of creepage mutual inductor, creepage mutual inductor secondary coil can be detected and to be currently in any state in " normal, broken string, short circuit ", external redundant current value can be calculated simultaneously.
The concrete technical scheme realizing the object of the invention is:
A pick-up unit for the open circuit of creepage mutual inductor secondary coil and short circuit, feature is that this device comprises residual current signal detection module, amplifier module and main control module, and residual current signal detection module connects amplifier module, amplifier model calling main control module;
Sampling resistor R1 in described residual current signal detection module is according to Ohm law sampling DC voltage component currency, amplifier module amplifies this DC voltage component, and main control module judges the current state of creepage mutual inductor secondary coil by calculating the DC voltage component value after amplifying; Current for creepage mutual inductor alternating current is converted to alternating current voltage component by the sampling resistor R1 in described residual current signal detection module, amplifier module amplifies this alternating current voltage component, and main control module goes out outside residual current value by this alternating current voltage component and sampling resistor R1 computing the resistor value.Wherein:
Described residual current signal detection module comprises sampling resistor R1 and pull-up resistor R2, sampling resistor R1 is in parallel with two signal output parts of creepage mutual inductor CT, sampling resistor R1 one end connects DC reference voltage VREF, the other end connects one end of pull-up resistor R2 and one end of R3, and the other end of pull-up resistor R2 connects direct supply VCC;
Described amplifier module comprises input resistance R3, amplifies resistance R4, filter resistance R5, differential mode capacitor C1, filter capacitor C2 and operational amplifier U1, input resistance R3 one end and the A of sampling resistor R1 holds connected, the other end to be connected to amplify resistance R4, differential mode capacitor C1 and operational amplifier U1 negative input end 2; The other end amplifying resistance R4 connects filter resistance R5 and operational amplifier U1 output terminal 3; The other end concatenation operation amplifier U1 positive input terminal 1 of differential mode capacitor C1 and DC reference voltage VREF; The other end of filter resistance R5 connects one end of filter capacitor C2 and the ADC Measurement channel of main control module, the other end ground connection of filter capacitor C2;
Described main control module is the single-chip microcomputer U2 of band ADC Measurement channel.
The present invention without the need to increasing extra detection current module in the primary winding or secondary coil loop of creepage mutual inductor, creepage mutual inductor secondary coil can be detected and to be currently in any state in " normal, broken string, short circuit ", external redundant current value can be calculated simultaneously.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Fig. 2 is main control module workflow diagram of the present invention.
Embodiment
Consult Fig. 1, the present invention includes residual current signal detection module, amplifier module and main control module, described residual current signal detection module is made up of sampling resistor R1, pull-up resistor R2, and sampling resistor R1 is in parallel with two signal output parts of creepage mutual inductor CT, R
ofor the internal resistance of creepage mutual inductor CT, the B end of sampling resistor R1 connects one end of A end connection pull-up resistor R2 of DC reference voltage VREF, R1 and one end of the input resistance R3 of amplifier module, and the other end of pull-up resistor R2 connects direct supply VCC, described amplifier module is by input resistance R3, amplify resistance R4, filter resistance R5, differential mode capacitor C1, filter capacitor C2 and operational amplifier U1 forms, input resistance R3 one end is held with the A of sampling resistor R1 and is connected, the R3 other end connects amplification resistance R4, differential mode capacitor C1 and operational amplifier U1 negative input end 2, the other end amplifying resistance R4 connects filter resistance R5 and operational amplifier U1 output terminal 3, the other end of differential mode capacitor C1 is all connected DC reference voltage VREF with operational amplifier U1 positive input terminal 1, the other end of filter resistance R5 is connected the ADC Measurement channel of main control module with one end of filter capacitor C2, the other end ground connection of filter capacitor C2, described main control module is the single-chip microcomputer U2 of band ADC Measurement channel.
In above-mentioned detection device, creepage mutual inductor CT and sampling resistor R1 forms loop, the A end of sampling resistor R1 is connected to VCC by pull-up resistor R2, the B end of sampling resistor R1 is connected to reference dc voltage VREF, A, B both end voltage of sampling resistor R1 is amplified through reverse operational amplification circuit, the filtering circuit that resistance R5 and filter capacitor C2 is formed after filtering is again input to the ADC Measurement channel of main control module U2, and the AD sampled value of main control module U2 measured by ADC Measurement channel calculates DC voltage value and ac voltage.
The present invention can detect the current any state be in " normally, broken string, short circuit " of creepage mutual inductor secondary coil, external redundant current value can be calculated simultaneously, computing method are as follows: creepage mutual inductor CT samples to external communication residual current signal, the interchange residual current obtained flows through the loop that creepage mutual inductor CT and sampling resistor R1 is formed, and is alternating current voltage component corresponding to this interchange residual current according to the alternating voltage at Ohm law R1 two ends; The internal resistance R of direct supply VCC, DC reference voltage VREF, pull-up resistor R2, sampling resistor R1, creepage mutual inductor CT
othe circuit formed, measures R1 two ends according to Ohm law and can obtain DC voltage component; Aforementioned DC voltage component and alternating current voltage component are sent to main control module through the amplification of amplifier module with analog quantity form, calculate dc-bias and AC value after carrying out analog to digital conversion via the ADC Measurement channel in main control module.When the generation open circuit of mutual inductor secondary coil, the DC voltage value of measurement is between 0 and VREF, and ac voltage is 0; When mutual inductor secondary coil is short-circuited, the DC voltage value of measurement is VREF, and ac voltage is 0; When open circuit or short circuit do not occur mutual inductor secondary coil, the DC voltage value of measurement is comparatively large but be less than VERF, ac voltage and external redundant current value linear correlation.
Consult Fig. 2, the course of work of main control module of the present invention: after main control module obtains voltage sample value, DC voltage component is calculated, and compare with the DC voltage component theoretical value when open circuit of creepage mutual inductor secondary coil, short circuit, normal three kinds of states, judge the current state of creepage mutual inductor secondary coil thus; As creepage mutual inductor secondary coil is in short circuit or off state, then main control module mark creepage mutual inductor current state; As creepage mutual inductor secondary coil is in normal condition, main control module normally can calculate the external redundant electric current measured by creepage mutual inductor.
Computing formula and the comparative approach of DC voltage component and alternating current voltage component are as follows:
When the open circuit of creepage mutual inductor secondary coil, the formula that main control module calculates DC voltage is:
DC voltage Vdc1=VREF-(VCC-VREF) * R1/ (R1+R2) * (R4/R3);
When the short circuit of creepage mutual inductor secondary coil, the formula that main control module calculates DC voltage is:
DC voltage Vdc2=VREF;
When creepage mutual inductor secondary coil is in normal condition, the formula that main control module calculates DC voltage is:
DC voltage Vdc3=VREF-(VCC-VREF) * R1 '/(R1 '+R2) * (R4/R3); (R1 ' in formula is creepage mutual inductor CT internal resistance R
owith the parallel resistance value of R1 resistance), in above formula, VREF, VCC, R1, R2, R3, R4, R1 ' value when meeting certain condition, the value difference of Vdc1, Vdc2, Vdc3 is comparatively large, and main control module can judge the current state of creepage mutual inductor secondary coil accordingly.
Assuming that VREF=1/2VCC, R4/R3=4, R2/R1=3, R1/ R1 '=4, it can thus be appreciated that Vdc1=0, Vdc2=VREF, Vdc3=9/13VREF, the current DC voltage and 0 calculated, these three values of VREF, 9/13VREF compare by main control module, judge the current state of creepage mutual inductor secondary coil.
VREF, VCC, R1, R2, R3, R4, R1 ' value do not require to be fixed as above-described proportionate relationship, as long as can meet Vdc1, Vdc2, Vdc3 value difference larger this point the current shape of main control module to creepage mutual inductor secondary coil can be allowed to judge.
The computing formula of alternating current voltage component is as follows:
When the open circuit of creepage mutual inductor secondary coil, alternating voltage Vac1=0;
When the short circuit of creepage mutual inductor secondary coil, alternating voltage Vac2=0;
When creepage mutual inductor secondary coil is in normal condition, the formula that main control module calculates alternating voltage is:
Alternating voltage Vac3=(I*R1) * (R4/R3), wherein I external redundant electric current two sub-value of sampling for creepage mutual inductor secondary coil, when R1, R3, R4 are determined value, alternating voltage Vac3 and I linear correlation, namely main control module calculates external redundant current value under normal circumstances.
Embodiment 1
VREF=2.5V，VCC=5V，R1=100Ω，R1’=25Ω，R2=300Ω，R3=10K，R4=40K。When the open circuit of creepage mutual inductor secondary coil, DC voltage Vdc1=VREF-(VCC-VREF) * R1/ (R1+R2) * (R4/R3)=0V; When the short circuit of creepage mutual inductor secondary coil, DC voltage Vdc2=VREF=2.5V;
When creepage mutual inductor secondary coil is in normal condition, DC voltage Vdc3=VREF-(VCC-VREF) * R1 '/(R1 '+R2) * (R4/R3)=1.73V; Alternating voltage Vac3=(I*R1) * (R4/R3)=400I, i.e. I=Vac3/400.
Main control module according to the size of DC voltage value measured during creepage mutual inductor secondary coil different conditions, then can consider the measuring error factor of suitable size, judges creepage mutual inductor secondary coil current state.In embodiment 1, the criterion of main control module is: when DC voltage value is within the scope of 0V-0.1V, and creepage mutual inductor secondary coil is off state; When DC voltage value is within the scope of 1.6V-1.8V, creepage mutual inductor secondary coil is normal condition; When DC voltage value is within the scope of 2.4V-2.6V, creepage mutual inductor secondary coil is short-circuit condition; When DC voltage value is within the scope of other, this monitoring device of master control module judges is in abnormality; When creepage mutual inductor secondary coil is normal condition, external redundant electric current two sub-value I=Vac3/400.
Embodiment 2
VREF=2.5V，VCC=5V，R1=100Ω，R1’=25Ω，R2=300Ω，R3=10K，R4=20K。When the open circuit of creepage mutual inductor secondary coil, DC voltage Vdc1=VREF-(VCC-VREF) * R1/ (R1+R2) * (R4/R3)=1.25V; When the short circuit of creepage mutual inductor secondary coil, DC voltage Vdc2=VREF=2.5V;
When creepage mutual inductor secondary coil is in normal condition, DC voltage Vdc3=VREF-(VCC-VREF) * R1 '/(R1 '+R2) * (R4/R3)=2.12V; Alternating voltage Vac3=(I*R1) * (R4/R3)=200I, i.e. I=Vac3/200.
Main control module according to the size of DC voltage value measured during creepage mutual inductor secondary coil different conditions, then can consider the measuring error factor of suitable size, judges creepage mutual inductor secondary coil current state.In example 2, the criterion of main control module is: when DC voltage value is within the scope of 1.15V-1.35V, and creepage mutual inductor secondary coil is off state; When DC voltage value is within the scope of 2.02V-2.22V, creepage mutual inductor secondary coil is normal condition; When DC voltage value is within the scope of 2.4V-2.6V, creepage mutual inductor secondary coil is short-circuit condition; When DC voltage value is within the scope of other, this monitoring device of master control module judges is in abnormality; When creepage mutual inductor secondary coil is normal condition, external redundant electric current two sub-value I=Vac3/200.
Embodiment 3
VREF=2.5V，VCC=5V，R1=100Ω，R1’=25Ω，R2=200Ω，R3=10K，R4=20K。When the open circuit of creepage mutual inductor secondary coil, DC voltage Vdc1=VREF-(VCC-VREF) * R1/ (R1+R2) * (R4/R3)=0.83V; When the short circuit of creepage mutual inductor secondary coil, DC voltage Vdc2=VREF=2.5V;
When creepage mutual inductor secondary coil is in normal condition, DC voltage Vdc3=VREF-(VCC-VREF) * R1 '/(R1 '+R2) * (R4/R3)=1.94V; Alternating voltage Vac3=(I*R1) * (R4/R3)=200I, i.e. I=Vac3/200.
Main control module according to the size of DC voltage value measured during creepage mutual inductor secondary coil different conditions, then can consider the measuring error factor of suitable size, judges creepage mutual inductor secondary coil current state.In embodiment 3, the criterion of main control module is: when DC voltage value is within the scope of 0.73V-0.93V, and creepage mutual inductor secondary coil is off state; When DC voltage value is within the scope of 1.84V-2.04V, creepage mutual inductor secondary coil is normal condition; When DC voltage value is within the scope of 2.4V-2.6V, creepage mutual inductor secondary coil is short-circuit condition; When DC voltage value is within the scope of other, this monitoring device of master control module judges is in abnormality; When creepage mutual inductor secondary coil is normal condition, external redundant electric current two sub-value I=Vac3/200.
Claims (3)
1. the pick-up unit of creepage mutual inductor secondary coil open circuit and short circuit, it is characterized in that this device comprises residual current signal detection module, amplifier module and main control module, residual current signal detection module connects amplifier module, amplifier model calling main control module; Wherein:
Described residual current signal detection module comprises sampling resistor R1 and pull-up resistor R2, sampling resistor R1 is in parallel with two signal output parts of creepage mutual inductor CT, sampling resistor R1 one end connects DC reference voltage VREF, the other end connects one end of pull-up resistor R2 and one end of R3, and the other end of pull-up resistor R2 connects direct supply VCC;
Described amplifier module comprises input resistance R3, amplifies resistance R4, filter resistance R5, differential mode capacitor C1, filter capacitor C2 and operational amplifier U1, input resistance R3 one end and the A of sampling resistor R1 holds connected, the other end to be connected to amplify resistance R4, differential mode capacitor C1 and operational amplifier U1 negative input end 2; The other end amplifying resistance R4 connects filter resistance R5 and operational amplifier U1 output terminal 3; The other end concatenation operation amplifier U1 positive input terminal 1 of differential mode capacitor C1 and DC reference voltage VREF; The other end of filter resistance R5 connects one end of filter capacitor C2 and the ADC Measurement channel of main control module, the other end ground connection of filter capacitor C2;
Described main control module is the single-chip microcomputer U2 of band ADC Measurement channel.
2. pick-up unit according to claim 1, it is characterized in that sampling resistor R1 in described residual current signal detection module is according to Ohm law sampling DC voltage component currency, amplifier module amplifies this DC voltage component, and main control module judges the current state of creepage mutual inductor secondary coil by calculating the DC voltage component value after amplifying.
3. pick-up unit according to claim 1, it is characterized in that current for creepage mutual inductor alternating current is converted to alternating current voltage component by the sampling resistor R1 in described residual current signal detection module, amplifier module amplifies this alternating current voltage component, and main control module goes out outside residual current value by this alternating current voltage component and sampling resistor R1 computing the resistor value.
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| 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 |
| 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 |
| WO2017028028A1 (en) * | 2015-08-14 | 2017-02-23 | General Electric Company | Systems and methods for open fault detection |
| 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 |
| CN111474401A (en) * | 2020-04-27 | 2020-07-31 | 长园共创电力安全技术股份有限公司 | High-voltage charged display device with fault detection function and fault detection method |
| CN111487469A (en) * | 2020-06-04 | 2020-08-04 | 国网江苏省电力有限公司宿迁供电分公司 | Current transformer secondary circuit contact resistance live detection device |
| CN113341202A (en) * | 2021-06-09 | 2021-09-03 | 国网陕西省电力公司电力科学研究院 | Method and system for detecting measurement precision of arc suppression coil capacitance current |
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| CN113341202A (en) * | 2021-06-09 | 2021-09-03 | 国网陕西省电力公司电力科学研究院 | Method and system for detecting measurement precision of arc suppression coil capacitance current |
| CN113341202B (en) * | 2021-06-09 | 2023-09-26 | 国网陕西省电力公司电力科学研究院 | Method and system for detecting capacitance current measurement precision of arc suppression coil |
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Application publication date: 20150722 |