CN2058791U - Leakage protector of electronic device - Google Patents

Abstract

The utility model discloses an electricity leakage protector for an electronic device which aims at the complexity of the electricity waveform of the electricity leakage of an electric device, providing an electricity leakage protector which can adapt to the change of peak value factor of the electricity of electricity leakage. The method of the electricity leakage protector for an electronic device is that the output end of a zero sequence current mutual inductance is connected with low impedance; or AC current, and the zero sequence current mutual inductance is offset; or the technology of magnetically modulating is adopted; or the change of the inductance of a nonlinear magnetic permeability magnetic core coil is adopted; when passing an integral circuit, an action valve value lying on the average value of electricity which leaks can all be achieved. The adopting effect of unidirectional electricity leakage, and change of waveform is suitable for electricity leakage production for an environment of electron, and electric appliance.

Description

Leakage protector of electronic device

The utility model is a kind of earth leakage protective device; belong to low-voltage electrical apparatus, because non-linear element is a lot of in the electronic equipment, their voltage current waveform more complicated; the waveform of leakage current is also complicated; along with the equipment difference, load difference, electric leakage position difference; or operating state difference; the waveform of leakage current is also different, and crest factor (peak value/mean value) is also inequality, and the polarity of leakage current and phase place also have multiple situation and occur.Existing earth leakage protective device; from detecting on the principle; basically be to detect the flux change rate that causes by electric leakage; so just two problems are arranged; the one, responsive to the permeability variation of magnetic core; after unipolarity electric leakage or big current magnetization, the magnetic core permeability may reduce, and sensitivity is changed; the 2nd, after the output voltage integration; just proportional with the amplitude of leakage current, thisly can not adapt to the occasion of peak value factors vary, because for the leakage current of same effective value or mean value to the protector of amplitude sensitivity; because peak value is different; this protector will have differential responses, and this is inconvenient, and it makes the desired action current notion unclear.

The utility model has proposed a kind of action threshold values at above situation and has depended on leakage current mean value; the unipolarity electric leakage is identical with ac leakage sensitivity on the mean value meaning; and action sensitivity changes little earth leakage protective device when the leakage current phase place changes, and can adapt at electronic apparatus electric leakage waveform complex environment to use.

Responsive and effective to the unipolarity electric leakage to mean value in order to realize, the utility model has adopted following four kinds of concrete grammars.

The first allows zero-sequence transformer be operated in approximate current instrument transformer state, and the output load impedance is less, and this moment, output was proportional to leakage current, and integration then is proportional to the leak level average later on.And the variation that inserts the little many magnetic cores magnetic permeability of impedance ratio coil induction reactance owing to output is also just smaller to the influence of output.Adopt linearity core material preferably, absolute value circuit and integrating circuit make output control voltage be proportional to the mean value of leakage current, and irrelevant with leakage current polarity.

It two is that zero-sequence transformer adopts the material with higher differential permeability to make magnetic core, and with the alternating current biasing that is higher than supply frequency, makes it to be operated in the high magnetic permeability district, utilizes frequency difference to select electric leakage signal again, and usefulness has the 50H of certain Q value _ZSensitivity was non-directional when filter was finished integration and the electric leakage of bonding polarity.

It three is to adopt the magnetic modulation technique, utilize high magnetic conduction low strong stupid, the nonlinear magnetization characteristic of the symmetry of the core material of high squareness factor, to export by the residue magnetic potential modulation back that leakage current causes, because magnetic modulator is operated in the saturation region, thereby insensitive, thereby can solve unipolarity electric leakage problem to unidirectional magnetiztion.

It four is the variations that utilize the magnetic core coil inductance value with non-linear permeability, detect the size of leakage current, because the symmetry of magnetic material, just can solve the problem of two unipolarity electric leakage direction and sensitivity symmetries without absolute value circuit, because magnetization back permeability also has bigger variation, therefore increased the demagnetization button, it can be with test button or reset button interlock, promptly in the preceding demagnetization that resets.

Fig. 1 to Fig. 5 is the circuit theory of these four kinds of methods, and owing to power supply, actuator, ground connection instrument transformer, part principles such as test switch are identical, also few of new thing, so Fig. 2 has omitted them later on, this is more convenient for saying something.

Among Fig. 1, LLH is a zero sequence current mutual inductor, and JDH is the ground connection instrument transformer, the same D of power transformer B ₁～D ₄, C ₁C ₂And integrated regulator IC ₁IC ₂Constitute positive-negative power, IC ₃Be a current-to-voltage converter, IC ₄Same R ₄～R ₇D ₇D ₈Constitute absolute value circuit, R ₈C ₇Constitute integrating circuit, SCR, J constitutes actuator, D ₅D ₆Be protection IC ₃, D ₉Be the induced current of relay J of releasing, C ₆Be partiting dc capacitor, IC ₃～IC ₄It is integrated transporting discharging.

JDH adds a less alternating voltage in phase line between zero line and the ground, in electric power system neutral grounded (only just meaningful at this system earth leakage protective device); when zero line has short trouble over the ground; also have zero-sequence current and flow through LLH, make the protector outage, avoid accident to enlarge.

Because IC ₃Be the current-voltage conversion circuit of anti-phase input connection, its input impedance is very low, like this, to LLH, just has been operated in the current transformer state, flows through R ₃Electric current proportional with leakage current, through after the integration, just reflected the mean value of leakage current, IC ₄As absolute value circuit,, flow to C when being input as when negative ₇Electric current be ((R ₆)/(R ₄R ₇)-1/ (R ₅)) ui, when ui is timing, flow to C ₇Electric current be (Ui)/(R ₅), suitably selection element numerical value can make output u ₀=| ui|, like this, electric leakage has not just had directivity to circuit to unipolarity.

LLH adopts soft magnetic ferrite, and is better linear, and the variation of magnetic permeability is just littler to the influence of output after magnetization like this.

IC among Fig. 2 ₁～IC ₄Be integrated operational amplifier, IC ₁Constitute a Wien bridge circuit sine-wave oscillator, through R ₅Supply with LLH biasing R ₆C ₃Constitute low pass filter, filtering offset signal, IC ₂Be buffer stage, IC ₃Be the 50H that certain Q value is arranged _ZBand pass filter is by IC ₄Set the control trigger voltage.

Under AC bias, the equivalent permeability of LLH increases, because it is very short in the low permeability district time.Like this, the electric leakage signal superposition through frequency-selecting, just can take out electric leakage signal in biasing.Because this moment, permeability was bigger, to 50H _ZInduction reactance than R ₅Be greater, output voltage also is proportional to electric leakage signal, and through the integration of filter, exportable ratio is in the control signal of leakage current mean value, IC ₃Also be that Wen's bridge joint is gone into positive feedback loop, when loop gain was not more than 3, the circuit nonoscillatory can constitute frequency selective amplifier thus, transferred W adjustable gain and Q value, had certain Q value can guarantee that output signal is a pure sine wave, and positive negative peak is symmetry also.For the unipolarity electric leakage of different directions, output only differs 180 ° like this, and size is constant, and this has just guaranteed the symmetry of sensitivity.

IC among Fig. 3 ₁The sine wave of output is sent into LLH through transformer B, and the zero-sequence transformer that LLH makes magnetic core by the low strong stupid high squareness factor material of two high magnetic conductions of usefulness constitutes, and with their output winding differential concatenation, the modulation sinusoidal ac is magnetized into two magnetic cores saturated, IC ₂Be a double T trapper, filter modulation signal, IC ₃Be that the frequency selective amplifier of a resonance on two times of modulating frequencies also is band pass filter, D ₃Detection, R ₁₈C ₈Integration, IC ₄The action sensitivity of adjusting.

Just often, because the magnetization curve symmetry, modulated current is symmetry also, second harmonic output will be provided with at output, when electric leakage, in two magnetic cores, the symmetry of magnetization curve will be destroyed with opposite direction, make output that even-order harmonic output be arranged, amplify through frequency-selecting, it has reflected the size of leakage current, through detection, integration, become the control signal that is proportional to leakage current mean value, because two instrument transformer symmetries, thereby to two unipolarity electric leakage directions, sensitivity is identical.

Because two magnetic cores can not be in full accord, thereby peak voltage output is arranged, when not leaking electricity, because symmetry, this peak voltage does not have even-order harmonic, by IC ₂Trap circuit filters fundamental frequency, can reduce the interference to two octave filters.

The magnetic modulator of Fig. 4 circuit is the same with Fig. 3 circuit, and just the modulation square wave detects with peak difference detection, integration 50H _ZBand pass filter.

IC among the figure ₁Be square-wave oscillator, IC ₂Make the buffering of peak difference detection, IC ₃Be band pass filter, IC ₄Be that control voltage is set level.

Because magnetic modulator two magnetic cores are incomplete same, just there is the magnetic hysteresis loop of a magnetic core narrower, it just is introduced into saturated like this, thereby make output peak voltage occur, the symmetry of magnetization curve during owing to do not leak electricity, the size and the area of positive and negative peak voltage equate, when electric leakage is arranged, symmetry is destroyed, variation has all taken place in the peak voltage size and the area of output, difference has been arranged between positive and negative, and this difference is proportional with leakage current, therefore after peak difference detection, output voltage is proportional through frequency selective amplifier filtering with electric leakage, integration, become the control signal of reflection leak level average, differ 180 ° on the phase place at most, then do not have directivity on the amplitude.

Peak difference wave detector is by D ₁D ₂, R ₁R ₂, C ₁～C ₃Form, during work, because D ₁D ₂Unilateral conduction, C ₁C ₂The positive and negative crest voltage of last maintenance instrument transformer output, their difference is at C ₃On reflect, through IC ₂After the buffering, become electric leakage signal.

The LLH of Fig. 5 circuit makes magnetic core with non-linear permeability material, when leakage current makes the skew of magnetic core working point, permeability changes, thereby inductance value also changes, can detect leakage current thus, because magnetization curve is symmetrical, the electric leakage of opposed polarity is the same to the influence of inductance value, so it does not have directivity.

IC among the figure ₁Be sine-wave oscillator, through R ₆To L ₂C ₃The loop provides a little operating current, and when not having electric leakage, inductance value is less, and the loop off resonance is big, and output voltage is little, through D ₃Detection C ₄R ₁₀After the integration, undertension is to promote IC ₄, when electric leakage, inductance value increases with the skew of working point, and output voltage also increases, C ₄Last voltage also increases, and inductance value is relevant with the electric leakage amplitude, and then the integration of voltage is then relevant with the leak level average on the inductance, thereby control voltage is proportional to the leak level average.

Among Fig. 1 to Fig. 5, power supply, control circuit and executive circuit are not simplified very much, but because their principle is very simple, can design in addition as required in actual applications, each filter and amplifier also can design in addition according to the components and parts situation, do not influence the realization of each figure principle.

Claims (8)

1, a kind of earth leakage protective device; mainly by zero sequence current mutual inductor; control circuit; protection actuator and accessory power supply are formed; the magnetic core magnetic permeability that it is characterized in that zero sequence current mutual inductor is better linear; and mutual inductance output load impedance is not more than 1/3rd of its induction reactance, and before control is judged absolute value circuit and integrating circuit is arranged.

2, according to the described protector of claim 1; it is characterized in that the zero sequence current mutual inductor magnetic core has higher differential permeability, and be higher than the alternating current biasing of supply frequency, make it to be operated in the high magnetic permeability section; and instrument transformer output back has one to have certain Q value, and centre frequency is 50H _ZFilter.

3, according to the described protector of claim 1, it is characterized in that zero sequence current mutual inductor is a magnetic modulator, utilize the nonlinear characteristic of core material symmetry, will export by the residue magnetic potential modulation back that leakage current causes, through the demodulation integration, judge control again.

4, according to the described protector of claim 1; it is characterized in that zero sequence current mutual inductor is a controllable impedance that is subjected to leakage current control; its magnetic core adopts the nonlinear magnetism conductivity material to make; utilize alternating current biasing, the variation of inductance value is converted into the signal of telecommunication through controlling judgement after the integration again.

5,, it is characterized in that utilizing electric current one voltage changer of anti-phase input connection, as the load of zero-sequence transformer according to the described control circuit of claim 1.

6, according to the described protector of claim 3, the output that it is characterized in that instrument transformer is through peak difference detection, has certain Q value, 50H by one again _ZThe filter integration is just judged at last.

7,, it is characterized in that the filter frequency-selecting of the output of zero-sequence transformer, and detection and integrating circuit are arranged through two times of modulating frequencies according to the described protector of claim 3.

8, according to the described protector of claim 4, it is characterized in that shunt capacitance on the instrument transformer secondary coil, constitute the LC loop, detect the variation of inductance value to utilize the biasing AC power.

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