CN100595595C - High precision broad frequency contaminated insulator leakage current sensor - Google Patents

Abstract

The utility model discloses a leakage current sensor with high precision broadband pollution insulator, relating to an insulator AC leakage current detection sensor. The sensor of the utility model mainly comprises Rogowski coil and an integral amplifying unit and a coaxial cable; the Rogowski coil and the integral amplifying unit are connected through the coaxial cable. The utility model has theadvantages of strongly anti-interfering ability, high detecting precision, sensibility up to 8.3mV/mA, bandwidth up to 2Hz to 100kHz, amplitude range of detecting current reaching 10MuA to 450mA; thusthe utility model is widely used in online monitoring of insulator leakage current of power transmission line and transformer station and is also used for micro-current or small current monitoring ofother electrical and electronic devices such as grounding current, leakage current and harmonic current.

Description

High precision broad frequency contaminated insulator leakage current sensor

Technical field

The invention belongs to the insulation of electrical installation monitoring technical field, particularly insulator ac leakage current detecting sensor.

Background technology

It is large-scale matter of regional significance that insulator pollutes, in case pollution flashover accident takes place, the spread area is big, and longer duration is one of serious problems that threaten the power system security transmission of electricity, must pay much attention to.Along with the development of industrial economy, the transmission voltage grade improves constantly, and the pre-tetrandra root of the pollution flashover of insulator becomes current electric system and is badly in need of one of problem of research.

After insulator surface pollutes, just pollution flashover may take place when running into meteorological condition such as mist, dew, drizzle, snowfall.Under the wet condition, insulator contamination amount is big more, and content of material water-soluble in the dunghill, that can conduct electricity is big more, and leakage current is big more.And whether pollution flashover big or small closely related with leakage current taken place, and after leakage current increased to a certain degree, pollution flashover just may take place.It is exactly through staining the leakage current data of insulator chain inflow earth mat in the real time record transmission line of electricity that contaminated insulator leakage current is carried out on-line monitoring, and complete and accurate note the actual change process of leakage current, the waveform of recorded and stored leakage current and various parameter, the situation of leakage current before and after the storage pollution flashover accident takes place, analyze culprit, carry out the foundation of pollution flashover early warning, fault diagnosis and location as the operations staff, be the generation of prevention insulator contamination accident, guarantee the effective measures of safe operation of power system.

Existing insulator leakage current on-line monitoring is by current sensor leakage current signal to be introduced Acquisition Circuit to carry out data acquisition, uses various algorithms to measure, calculate afterwards.Therefore current sensor is the critical component of On-line Monitoring of Leakage Current system.Leakage current signal has the characteristics of amplitude variation range big (tens microamperes to the hundreds of milliampere), bandwidth (power frequency to tens KHz), therefore requires sensor to have the performance highly sensitive, that working band is wide.Current sensor commonly used at present can be divided into electric contact current sensor and non-electric contact current sensor from installation form.Electric contact current sensor is shunt or collector ring normally, though can reach the higher precision and the frequency band of broad, takes this method to understand short circuit a slice insulator usually, has reduced the insulating property of circuit, and this is unallowed in a lot of occasions.Non-electric contact current sensor is made up of the Rogowsky coil (hereinafter to be referred as " Rogowski coil ") and the external integrating resistor of ribbon core, and this type of sensor is referred to as the core-theaded type current sensor.Wear current sensor and Chinese publication number is " high-accuracy ac leakage current on-line monitoring sensor " disclosed current sensor of CN 1564008A as " development of pin-point accuracy low current sensor " disclosed single core of " sensor technology " 2004 the 23rd the 12nd phase of volume.This current sensor is made up of Rogowski coil and integrating resistor.The Rogowski coil is made of annular core, coil, insulation film, permalloy film, iron sheet film, shielding box and BNC.But theory and practice all proves the core-theaded type current sensor and has self intrinsic defective: 1. precision is low under little current signal; 2. can't take into account between frequency band and the sensitivity; 3. be subjected to on-the-spot disturbing effect big.Because above-mentioned inherent shortcoming, the core-theaded type current sensor is subjected to some restrictions in application, and is poor in needs high precision, its effect of wide band application.

Summary of the invention

The objective of the invention is deficiency, a kind of high precision broad frequency insulator leakage current sensor is provided, characteristics such as have precision height, bandwidth, the linearity is good, antijamming capability is strong at existing core-theaded type current sensor.

The technical scheme that realizes the object of the invention is as follows:

A kind of high precision broad frequency contaminated insulator leakage current sensor mainly comprises Rogowsky coil (Rogowski coil) and the integration amplifying unit and the concentric cable of ribbon core, is connected by concentric cable between Rogowski coil and the integration amplifying unit.The Rogowski coil is made up of nanometer crystal alloy annular core, winding, double-layer shielding structure, shell and coaxial fitting.In the enclosure, winding, nanometer crystal alloy annular core and double-layer shielding structure are set respectively from the inside to the outside, winding is on the nanometer crystal alloy annular core, and double-layer shielding structure is arranged on the upper and lower side and the lateral surface of Rogowski coil.The internal layer of double-layer shielding structure is a copper shield, outer for iron shield layer, thickness are 0.3mm～0.5mm, disturbs in order to the shielding external electromagnetic field.Filled polytetrafluoroethylene film between two screen layers, in order to the electrical link of isolated two screen layers, all there is the wide vertical fluting of 1mm～1.5mm in the outside of two screen layers, produces in order to prevent eddy current.Because this Rogowski coil is to be enclosed within the leakage current that detects insulator on the steel cap of tested insulator, so the size of Rogowski coil is by the size decision of insulator steel cap.Coaxial fitting is arranged on the lateral surface of shell.The integration amplifying unit mainly comprises front-end protection circuit, integrated operational amplifier, feedback resistance and filter capacitor; connect by lead between the element of integration amplifying unit; in order to constitute a closed-loop system; the passband gain of sensor can be regulated on the one hand by feedback resistance, the working band of sensor can be widened on the other hand.The input end of integration amplifying unit links to each other by the coaxial fitting of concentric cable with the Rogowski coil, and output terminal links to each other with the Acquisition Circuit of third-party on-line monitoring system.The detection current amplitude scope of leakage current sensor of the present invention is that 10 μ A～450mA, frequency range are that 2Hz～100kHz, sensitivity reach 8.3mV/mA.

After the present invention adopts technique scheme, mainly contain following characteristics:

1, the integration amplifying unit of the present invention's employing has replaced traditional integrating resistor, makes sensor to widen the frequency band of frequency of operation when guaranteeing response sensitivity, reaches high precision and wide band requirement.

If L _sBe coil inductance, R is an integrating resistor, R _sBe the resistance of coil copper, C _sBe stray capacitance, then the current sensor upper limiting frequency and the lower frequency limit of traditional quadrature resistance are respectively:

$f_h=\frac{L_s+{\mathrm{RR}}_s{\mathrm{<figure-callout\; id="2"\; label="C\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">C</figure-callout>}}_s}{2\mathrm{\&pi;}{L}_s{\mathrm{RC}}_s}\&ap;\frac{1}{2\mathrm{\&pi;}{\mathrm{<figure-callout\; id="1"\; label="RC\; s\; f"\; filenames="C2007100925230011H2.png,C2007100925230012H1.png"\; state="\{\{state\}\}">RC</figure-callout>}}_s}$ $f_{}$ ${}_1=\frac{R+{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_s}{2\mathrm{\&pi;}\&CenterDot;(L_s+{\mathrm{RR}}_s{C}_s)}\&ap;\frac{R+{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_s}{2\mathrm{\&pi;}{L}_s}$

Sensor will obtain bigger bandwidth, f _hThat should try one's best is big, and f ₁Should be as far as possible little, so should make L _sBig as far as possible, R is as far as possible little.Turn number N increases, L _sIncrease, the frequency band of current sensor broadens, but response sensitivity will descend.Under certain core material parameter and size, the frequency span of sensor and sensitivity will depend mainly on integrating resistor and coil turn, determining the low-frequency minimum and the high frequency limit of sensor by the visible integrating resistor R of following formula, R is more little, and lower-cut-off frequency is low more, and upper cut-off frequency is high more simultaneously, be that working band is wide more, but integrating resistor reduces to make the output voltage of sensor to descend, and very difficult quilt is accurately measured, thereby has influenced measuring accuracy.So should guarantee sensor enough sensitivity and precision are arranged, guarantee that again the frequency band of broad is to be difficult to realize for classic method.

Integration amplifying unit of the present invention can finely address the above problem, and is the integration amplifying unit that core constitutes by operational amplifier, and minimum input impedance R is provided _In, replace integrating resistor R, operational amplifier and feedback resistance R _fThe amplifying circuit of forming is a higher voltage with little current conversion.This moment, upper limiting frequency and lower frequency limit were respectively

$f_h=\frac{L_s+R_{\mathrm{in}}{R}_{\mathrm{<figure-callout\; id="2"\; label="s\; C\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">s</figure-callout>}}{C}_s{}_{}}{2\mathrm{\&pi;}{L}_s{\mathrm{RC}}_s}\&ap;\frac{1}{2\mathrm{\&pi;}{R}_{\mathrm{in}}{\mathrm{<figure-callout\; id="1"\; label="C\; s\; f"\; filenames="C2007100925230011H2.png,C2007100925230012H1.png"\; state="\{\{state\}\}">C</figure-callout>}}_s}$ $f_{}$ ${}_1=\frac{R_{\mathrm{in}}+{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_s}{2\mathrm{\&pi;}\&CenterDot;(L_s+R_{\mathrm{in}}{R}_s{C}_s)}\&ap;\frac{R_{\mathrm{in}}+{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C2007100925230012H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_s}{2\mathrm{\&pi;}{L}_s}$

Passband gain

So passband gain is not because minimum R _InAnd reduce, but by the feedback resistance R of integration amplifying unit _fDetermine with the number of turn N of Rogowski coil, and because input impedance R _InMinimum, respectively by very big raising and reduction, working band is well widened by the upper limiting frequency of following formula visible light transducer and lower frequency limit.More than explanation, integration amplifying unit of the present invention can this be independent to contradiction with conventional current transducer sensitivity and working band, reaches the effect that both take into account.

In general, it is big more to gain, and sensitivity is good more, measuring accuracy is high more, but the third-party on-line monitoring system of termination behind the sensor of the present invention, its input range has different requirements, therefore can obtain suitable gain by selecting suitable feedback resistance resistance.For cooperating the on-line monitoring system of independent development, as the feedback resistance resistance R of current sensor selection of the present invention _fBe 1k Ω, umber of turn is 120 o'clock, and the sensitivity that obtains sensor is 1000/120=8.3mV/mA.Meanwhile, because the R of integration amplifying unit _InMinimum, the working sensor frequency band is widened is 2Hz～100kHz.

2, the Rogowski mounting coil of the present invention's employing is on the steel cap of insulator, and its size depends on steel cap size.The electromagnetic interference (EMI) in the double-layer shielding structure energy good restraining external world has wherein improved antijamming capability, thereby has improved the accuracy of detection of sensor.All there is the wide vertical fluting of 1mm～1.5mm in the outside of two screen layers, be to treat that in order to prevent the side current signal produces eddy current and can't enter iron core by electromagnetic induction on screen layer, thereby make sensor can accurately produce the output corresponding, further improved accuracy of detection with leakage current.

3, the present invention selects for use the nanometer crystal alloy of excellent performance to make the iron core of Rogowski coil, winding layout on iron core is even, thereby make the current ratio on the former and deputy limit of Rogowski coil in very wide range of current, all equal umber of turn, obtained the good linearity.Test findings shows that current sensor of the present invention has good linearty in current amplitude 10 μ A～450mA.

Current sensor of the present invention, being used for the on-line monitoring amplitude is 10 μ A～450mA, frequency is the leakage current in 2Hz～100kHz scope, the on-line monitoring that can be widely used in the insulator leakage current of transmission line of electricity and transformer station also can be used for other electric power, little electric current of electronic equipment or the monitorings of little electric current such as ground current, leakage current, harmonic current.

Description of drawings

Fig. 1 is a Rogowski coil structure of the present invention;

Fig. 2 is the integration amplifying unit circuit diagram of embodiment;

Fig. 3 is the amplitude-versus-frequency curve figure of the leakage current sensor of actual measurement;

Fig. 4 is the linearity curve map of leakage current sensor;

Wherein: figure (a) is the linearity curve map of 10mA～450mA for the primary current amplitude, figure (b) is the linearity curve map of 1mA～10mA for the primary current amplitude, figure (c) is the linearity curve map of 10 μ A～1mA for the primary current amplitude, and figure (d) is the linearity curve map of gamut.

Fig. 5 is actual measurement leakage current oscillogram;

Wherein: figure (a) is slight filthy leakage current oscillogram, and figure (b) is the filthy leakage current oscillogram of moderate, and figure (c) is the filthy leakage current oscillogram of severe.

Fig. 6 is actual measurement leakage current oscillogram;

Wherein: figure (a) is the leakage current oscillogram when exerting pressure 10kV, figure (b) is the leakage current oscillogram when exerting pressure 15kV, figure (c) is the leakage current oscillogram when exerting pressure 25kV, figure (d) is the leakage current oscillogram when exerting pressure 30kV, and figure (e) is the leakage current oscillogram when exerting pressure 37kV.

Fig. 7 is actual measurement leakage current oscillogram.

Wherein: the leakage current oscillogram of figure (a) during for no icing, the leakage current oscillogram of figure (b) when certain icing is arranged, figure (c) is the leakage current oscillogram when a lot of icing is arranged.

Among the figure: 1 iron core, 2 concentric cable, 3 cable splices, 4 windings, 5 iron shield layers, 6 polytetrafluoroethylene films, 7 copper shields, 8 shells, the fluting of 9 screen layers, D1, D2 limiter diode, T1 bipolarity Transient Voltage Suppressor, R ₁Resistance, C ₁, C ₂, C ₃, C ₄Electric capacity, P1 cable splice, the ground of AGND circuit, U1 operational amplifier, Uout sensor output voltage.

Embodiment

Below in conjunction with embodiment, further specify the present invention.

Embodiment 1

As shown in Figure 1, 2, a kind of high precision broad frequency contaminated insulator leakage current sensor mainly comprises Rogowski coil and integration amplifying unit two large divisions, connects by concentric cable 2 therebetween.The Rogowski coil is that the shell 8 of engineering plastics is formed with coaxial fitting 3 by nanometer crystal alloy annular core 1, winding 4, double-layer shielding structure, material.In shell 8, winding 4, nanometer crystal alloy annular core 1 and double-layer shielding structure are set respectively from the inside to the outside, winding 4 by the enameled wire of diameter 0.19mm on nanometer crystal alloy annular core 1, the number of turn is 120 circles, double-layer shielding structure is arranged at the upper and lower side and the lateral surface of coil, and its internal layer is a copper shield 7, and skin is an iron shield layer 5, thickness is 0.5mm, disturbs in order to the shielding external electromagnetic field.Filled polytetrafluoroethylene film 6 between two screen layers is in order to the electrical link of isolated two screen layers.All there is the wide vertical fluting 9 of 1mm in the outside of two screen layers, produces in order to prevent eddy current, and coaxial fitting 3 is arranged on the lateral surface that material is the shell 8 of engineering plastics.The front-end protection circuit of integration amplifying unit by limiter diode D1, D2 and bipolarity Transient Voltage Suppressor T1 form, integrated operational amplifier U1, feedback resistance R ₁And filter capacitor C ₂, connect by lead between the element of integration amplifying unit, in order to constitute a closed-loop system, can regulate the passband gain of sensor on the one hand by feedback resistance, can widen the working band of sensor on the other hand.The cable splice P1 of integration amplifying unit links to each other with the cable splice 3 of Rogowski coil by concentric cable 2.Limiter diode D1, D2 model are 1N4007; bipolarity Transient Voltage Suppressor T1 model is 1.5KE16CA; end after D1, D2, the T1 parallel connection links to each other with the signal terminal of the cable splice P1 of integration amplifying unit and the inverting input of operational amplifier U1; the other end plays holding circuit with the ground terminal ground connection AGND of the cable splice P1 of integration amplifying unit.Between the inverting input of operational amplifier U1 and ground AGND, connect capacitor C 1, play the effect of filtering high frequency interference as 500pF.Operational amplifier U1 model is AD711, and its inverting input connects the output signal of Rogowski coil, following phase input end grounding AGND, and power pins connects respectively+15V ,-the 15V power supply, and use filter capacitor C respectively ₄, C ₃Do bypass, capacitance is 0.1 μ F, meets feedback resistance R between normal phase input end and the output terminal ₁With filter capacitor C ₂, its value is respectively 1k Ω, 200pF, and sensor output voltage Uout links to each other with the Acquisition Circuit of third-party on-line monitoring system, so that simulating signal is carried out analog to digital conversion, and then the monitoring leakage electric current.

The enlargement factor of integration amplifying unit is by feedback resistance R ₁Decision, enlargement factor is 1000 in the present embodiment, because the input range difference of third-party on-line monitoring system, can be by adjusting feedback resistance R ₁Size obtain suitable enlargement factor and do not influence frequency characteristic.Because the input impedance of integration amplifying unit is minimum, replacing traditional integrating resistor by it can not widen frequency band in the desensitization.The amplitude that the leakage current sensor of present embodiment is measured electric current is 10 μ A～450mA, and frequency is 2Hz～100kHz, and sensitivity reaches 8.3mV/mA.

Embodiment 2

A kind of high precision broad frequency contaminated insulator leakage current sensor mainly comprises Rogowski coil and integration amplifying unit two large divisions, connects by concentric cable 2 therebetween.The Rogowski coil is that the shell 8 of engineering plastics is formed with coaxial fitting 3 by nanometer crystal alloy annular core 1, winding 4, double-layer shielding structure, material.In shell 8, winding 4, nanometer crystal alloy annular core 1 and double-layer shielding structure are set respectively from the inside to the outside, winding 4 by the enameled wire of diameter 0.19mm on nanometer crystal alloy annular core 1, the number of turn is 120 circles, double-layer shielding structure is arranged at the upper and lower side and the lateral surface of coil, and its internal layer is a copper shield 7, and skin is an iron shield layer 5, thickness is 0.5mm, disturbs in order to the shielding external electromagnetic field.Filled polytetrafluoroethylene film 6 between two screen layers is in order to the electrical link of isolated two screen layers.All there is the wide vertical fluting 9 of 1.5mm in the outside of two screen layers, produces in order to prevent eddy current, and coaxial fitting 3 is arranged on the lateral surface that material is the shell 8 of engineering plastics.The front-end protection circuit of integration amplifying unit is by limiter diode D1, D2, bipolarity Transient Voltage Suppressor T1 composition, integrated operational amplifier U1, feedback resistance R ₁And filter capacitor C ₂, connect by lead between the element of integration amplifying unit, in order to constitute a closed-loop system, can regulate the passband gain of sensor on the one hand by feedback resistance, can widen the working band of sensor on the other hand.The cable splice P1 of integration amplifying unit links to each other with the cable splice 3 of Rogowski coil by concentric cable 2.Limiter diode D1, D2 model are 1N4007; bipolarity Transient Voltage Suppressor T1 model is 1.5KE16CA; end after D1, D2, the T1 parallel connection links to each other with the signal terminal of the cable splice P1 of integration amplifying unit and the inverting input of operational amplifier U1; the other end plays holding circuit with the ground terminal ground connection AGND of the cable splice P1 of integration amplifying unit.Between the inverting input of operational amplifier U1 and ground AGND, connect capacitor C 1, play the effect of filtering high frequency interference as 500pF.Operational amplifier U1 model is AD711, and its inverting input connects the output signal of Rogowski coil, positive input end grounding AGND, and power pins connects respectively+15V ,-the 15V power supply, and use filter capacitor C respectively ₄, C ₃Do bypass, capacitance is 0.1 μ F, meets feedback resistance R between normal phase input end and the output terminal ₁With filter capacitor C ₂, its value is respectively 1k Ω, 200pF, and sensor output voltage Uout links to each other with the Acquisition Circuit of third-party on-line monitoring system, so that simulating signal is carried out analog to digital conversion, and then the monitoring leakage electric current.

The enlargement factor of integration amplifying unit is by feedback resistance R ₁Decision, enlargement factor is 1000 in the present embodiment, because the input range difference of third-party on-line monitoring system, can be by adjusting feedback resistance R ₁Size obtain suitable enlargement factor and do not influence frequency characteristic.Because the input impedance of integration amplifying unit is minimum, replacing traditional integrating resistor by it can not widen frequency band in the desensitization.The amplitude that the leakage current sensor of present embodiment is measured electric current is 10 μ A～450mA, and frequency is 2Hz～100kHz, and sensitivity reaches 8.3mV/mA.

Test findings

Sensor with embodiment 1 carries out following test:

1, the test of the amplitude versus frequency characte and the linearity.Method of testing is: produce various voltage signals with signal generator, the resistance of certain resistance is connected on the voltage two ends, produces the known electric current of size, current carrying conductor is passed the Rogowski coil, with the output voltage of oscilloscope measurement sensor, its result as shown in Figure 3, Figure 4.

Fig. 3 is amplitude-versus-frequency curve figure, and therefrom as can be seen, the frequency that is lower than smooth band 3dB correspondence is 2Hz, and smooth band extends to 100kHz, so the working band of this sensor is 2Hz～100kHz, shows good frequency characteristic.

Fig. 4 is a linearity curve map, the former limit punching current amplitude of Rogowski coil when transverse axis is test, and the longitudinal axis is sensor output voltage amplitude Uout, divides between each Current Zone and has tested the linearity.Show among the figure that leakage current sensor of the present invention has good linearty at current amplitude 10 μ A～450mA, sensitivity reaches 8.3mV/mA, satisfies the insulator leakage current on-line monitoring to sensor high precision, wide band requirement.

2, the experiment with measuring of insulator leakage current.Test is carried out in the controlled environment chamber, experiment power supply be shifting coil voltage regulator TDJY-1000/10 and testing transformer YDJ-900/150 form exchange the pollution test power supply, the rated current of testing transformer is 6A, its maximum short circuit current can reach 30A, satisfies IEC60507 and GB GB/T4584-2004 to exchanging the requirement of pollution test power supply.Pressure regulator produces the alternating voltage of 0～10kV, and testing transformer obtains testing high voltage with the output voltage rising of pressure regulator.The test high voltage is introduced phytotron by the 110KV wall bushing of artificial fog chamber one side installing, the test high-pressure side is connected to voltage table by SGB-200A ac capacitor formula voltage divider, the intrinsic standoff ratio of voltage divider is 1: 1000, and the reading by voltage table can record the trial voltage that is added on insulator.Test product is seven molecular insulator chains of insulation.Its result such as Fig. 5～shown in Figure 7.

Fig. 5 reflection is only filthy different, ambient humidity, applies other conditions such as voltage when identical, the comparison of wave shape of leakage current; Used insulator model is XP-70 among (a) and (b), (c), and equivalent salt density is respectively 0.03,0.1,0.2mg/cm ², promptly belong to slight filth, moderate filth and severe filth respectively.As can be seen from Figure 4, the leakage current that records increases the weight of and increases with filth, also has discharge pulse in (c).

Fig. 6 reflects the development and change rule that leakage current increases with executing voltage, and used insulator model is LXP-70, and equivalent salt density is 0.1mg/cm ²Apply phase voltage among (a) and (b), (c), (d), (e) and be respectively 35kV, 52.5kV, 87.5kV, 105kV, 129.5kV.Find out leakage current among the figure with applying the obvious increase of increasing of voltage, (d) a large amount of discharge pulses of middle appearance (e) are the waveform that faces before dodging, and wherein leakage current becomes greatly from large to small again, and it is right to show that occurrence of large-area electric arc weighs.

Fig. 7 reflects that same electrical depresses, when insulator chain is thickeied from the cleaning to the icing gradually, and the development and change rule of leakage current, used insulator model is LXP-70.Wherein (a) is the situation of insulator when clean, leakage current a little less than, can not cause that as can be known dielectric level descends this moment; (b) situation when certain icing is arranged, leakage current increases, wave form distortion; (c) be the situation of icing when a lot, leakage current further increases, and produces pulse, and the arc discharge phenomenon takes place as can be known, and icicle with adjacent insulator short circuit, is about to take place flashover.

In conjunction with the leakage current rule of development and measured result, the test result of leakage current sensor of the present invention can accurately reflect the Changing Pattern of insulator leakage current as can be known, and has a precision height, bandwidth, antijamming capability is strong, advantages such as mounting means is reasonable can accurately be measured leakage current, are the current sensors with applications well prospect of little electric currents such as insulator leakage current on-line monitoring and ground current, leakage current, harmonic current, little current detecting.

Claims (4)

1; a kind of high precision broad frequency contaminated insulator leakage current sensor; mainly comprise the Rogowski coil; concentric cable (2); it is characterized in that integration amplifying unit in addition; be connected by concentric cable (2) between Rogowski coil and the integration amplifying unit; the Rogowski coil is by nanometer crystal alloy annular core (1); winding (4); double-layer shielding structure; shell (8) and coaxial fitting (3) are formed; in shell (8); be respectively winding (4) from the inside to the outside; nanometer crystal alloy annular core (1) and double-layer shielding structure; winding (4) is on nanometer crystal alloy annular core (1); double-layer shielding structure is arranged on the side up and down and the lateral surface of winding (4); the internal layer of double-layer shielding structure is copper shield (7); skin is iron shield layer (5); thickness is 0.3mm～0.5mm; filled polytetrafluoroethylene film (6) between two screen layers; all there is the wide vertical fluting (9) of 1mm～1.5mm in the outside of two screen layers; coaxial fitting (3) is arranged on the lateral surface of shell (8); the integration amplifying unit mainly comprises the front-end protection circuit; integrated operational amplifier (U1); feedback resistance (R1) and filter capacitor (C2); connect by lead between the element of integration amplifying unit; the input end of integration amplifying unit links to each other with the coaxial fitting (3) of Rogowski coil by concentric cable (2), and output terminal links to each other with the Acquisition Circuit of third-party on-line monitoring system.

2, according to the described high precision broad frequency contaminated insulator leakage current sensor of claim 1, the detection current amplitude that it is characterized in that described sensor is that 10 μ A～450mA, frequency range are 2Hz～100kHz.

3; according to the described high precision broad frequency contaminated insulator leakage current sensor of claim 1; the material that it is characterized in that shell (8) is engineering plastics; winding (4) is that the enameled wire of 0.19mm is wound on the nanometer crystal alloy annular core (1) by diameter; the number of turn is 120 circles; the thickness of copper shield of double-layer shielding structure (7) and iron shield layer (5) is 0.5mm; all there is the wide vertical fluting (9) of 1mm in the outside of two screen layers; the front-end protection circuit of integration amplifying unit is by two limiter diode (D1; D2) and bipolarity Transient Voltage Suppressor (T1) form; two limiter diode (D1; D2) model is 1N4007; bipolarity Transient Voltage Suppressor (T1) model is 1.5KE16CA; two limiter diode (D1; D2) with bipolarity Transient Voltage Suppressor (T1) parallel connection after an end link to each other with the signal terminal of the cable splice (P1) of integration amplifying unit and the inverting input of integrated operational amplifier (U1); the other end is with the ground terminal ground connection (AGND) of the cable splice (P1) of integration amplifying unit; between the inverting input of integrated operational amplifier (U1) and ground (AGND), insert the electric capacity (C1) of 500pF; integrated operational amplifier (U1) model is AD711; its inverting input connects the output signal of Rogowski coil; positive input end grounding (AGND); power pins connects respectively+15V;-15V power supply, and use filter capacitor (C respectively ₄, C ₃) do bypass, capacitance is 0.1 μ F, meets feedback resistance (R between normal phase input end and the output terminal ₁), filter capacitor (C ₂), its value is respectively 1k Ω, 200pF, and sensor output voltage (Uout) links to each other with the Acquisition Circuit of third-party on-line monitoring system.

4; according to the described high precision broad frequency contaminated insulator leakage current sensor of claim 1; the material that it is characterized in that shell (8) is engineering plastics; winding (4) is that the enameled wire of 0.19mm is wound on the nanometer crystal alloy annular core (1) by diameter; the number of turn is 120 circles; the thickness of the copper shield of double-layer shielding structure and iron shield layer is 0.3mm; all there is the wide vertical fluting (9) of 1.5mm in the outside of two screen layers; the front-end protection circuit of integration amplifying unit is by two limiter diode (D1; D2) and bipolarity Transient Voltage Suppressor (T1) form; two limiter diode (D1; D2) model is 1N4007; bipolarity Transient Voltage Suppressor (T1) model is 1.5KE16CA; two limiter diode (D1; D2) with bipolarity Transient Voltage Suppressor (T1) parallel connection after an end link to each other with the signal terminal of the cable splice (P1) of integration amplifying unit and the inverting input of integrated operational amplifier (U1); the other end is with the ground terminal ground connection (AGND) of the cable splice (P1) of integration amplifying unit; between the inverting input of integrated operational amplifier (U1) and ground (AGND), insert the electric capacity (C1) of 500pF; integrated operational amplifier (U1) model is AD711; its inverting input connects Rogowski coil output signal; positive input end grounding (AGND); power pins connects respectively+15V;-15V power supply, and use filter capacitor (C respectively ₄, C ₃) do bypass, capacitance is 0.1 μ F, meets feedback resistance (R between normal phase input end and the output terminal ₁), filter capacitor (C ₂), its value is respectively 1k Ω, 200pF, and sensor output voltage (Uout) links to each other with the Acquisition Circuit of third-party on-line monitoring system.

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