CN1022203C - Electric quantity transducer and check meter of watt-hour meter - Google Patents

Abstract

The present invention relates to a detector, particularly to a detector for an electric quantity transmitter and an electric meter. The present invention is composed of a single-chip microcomputer system, a mutual inductor, a controller, an amplifier, an analogue multiplier, a low-pass filter, an amplifilter, an A/D converter, a ripple detection circuit, a phase frequency test circuit, a sampling frequency automatic tracking circuit, a voltage divider, etc. The detector has the characteristics of high precision, powerful function, intellectualization, small volume, light weight, high stability, convenient carrying, etc. The present invention is used for testing, adjusting and checking the alternating current voltage, the direct current voltage, the current, different power, different electric energy, various power factors and frequencies, etc. of various transmitters and various electric meters.

Description

Electric quantity transducer and check meter of watt-hour meter

The present invention is a kind of check meter, the check meter of particularly a kind of electric parameters transducer and ammeter.

In electric system, various electric parameters transducers of widespread use and various ammeter.Electric substation, transformer station from little at county level, greatly to electric power plant, transfer, economize accent and all have a large amount of transmitters to bear monitoring and control mission in the distribution system.The performance quality of transmitter will directly affect the work of electric system.Therefore, the power department regulation, must carry out an annual test every year to transmitter: carry out comprehensive checksum test to transmitter such as all 0.2～0.5 grade of ac and dc currents, voltage, power, electric degree, frequency, power factor (PF) and ammeter, need with check meter be a lot.The three-phase ac signal source of a degree of stability at 0.01%～0.02% frequency modulation, amplitude modulation, phase modulation at first will be arranged, then, also need be furnished with various standard scales, as standard dc digital voltmeter, standard direct-flow digital ammeter, standard ac digital reometer, standard AC digital voltmeter, meritorious idle (single-phase, the three-phase) digital power meter of standard, meritorious idle (single-phase, the three-phase) electric energy meter of standard, standard digital power frequency phase meter, standard work frequency meter etc.

Present electric parameters transducer checking table generally all is to utilize a plurality of pointer-type or digital instrument to combine to constitute a big estrade, comes transmitter is carried out checksum test.These estrades have some common shortcomings, the needs that promptly cost height, volume are big, heavy, precision is low, can not satisfy on-the-spot test.Owing to there is not intellectuality, the function of instrument is not strong, and complicated operation, time-consuming, Fei Gong, reading are not directly perceived, and the record test data and the error of calculation automatically.For example: the JJD-that Jiujiang instrucment and meter plant produces ⁰² ₀₃0.1 grade of type list, three phase watt-hour meter checking table, precision.Evaluate by exhibit at The Department of Electric Power of Ministry of Energy watt-hour meter calibration equipment in 1989 and to win one in the meeting, the prize of second-class quality product.But it remains the test board of being made up of a plurality of standard scales, and volume is big, cost is high, can only verification single, three phase watt-hour meter, can not detect various ammeters and transmitter.Its operating aspect with as above-mentioned can not be satisfactory.And for example: the XDB-that Liaoning Electronic Instruments Plant produces ^100A _100BType electric parameters transducer checking table, precision are 0.15 grade, need to be equipped with various master meters ability verification alternating voltages, electric current and three-phase are meritorious, the reactive power transmitter, and volume is big, heavy, can not carry out automatically and semi-automatic test, automatically the error of calculation and printing automatically, operation inconvenience.Therefore, develop a kind of precision height, volume is little, in light weight, cost is low, multi-functional check meter easy to carry, that can arrive on-the-spot test and calibrate various transmitters just becomes a urgent subject.

The objective of the invention is to for overcoming the deficiencies in the prior art, a kind of check meter that can realize multi-functional intelligent power transmitter and ammeter is provided, be characterized in that volume is little, in light weight, precision is high, function is strong, intelligent, easy to carry, the scene that can get at is carried out high-precision automatic and automanual test and is calibrated various transmitters and ammeter, because the present invention can directly demonstrate by each input quantity, output quantity and the error of the transmitter of verification, so thereby be easy to error is adjusted to the precision that zero raising is adjusted the transmitter of verification.

The present invention is realized by following measure.It comprises monolithic system 1, A/D converter 17, programmable amplifier 10 and 11, it is characterized in that it also comprises three-phase power socket 2, the transmitter input, accessory power outlet 3, mutual inductor 4, multi-way switch 5 and 6, controller 7 and 8, reference power supply 9, analog multiplier 12, low-pass filter 13, multi-way switch 14, controller 15, amplifilter 16, ripple detection circuit 18, phase frequency test circuit 19, sample frequency automatic tracking circuit 20, weak signal is amplified and compositions such as control circuit 21 and voltage divider 22, and the connecting relation of this technical scheme is as follows: Single Chip Microcomputer (SCM) system 1, respectively with external two power supplys 24,25, A/D converter 17, controller 7,8 and 15, weak signal is amplified and control circuit 21, programmable amplifier 10 and 11, phase frequency test circuit 19, sample frequency automatic tracking circuit 20 links; If tested transmitter is the electric degree transmitter, then its output pulse direct sending is gone into Single Chip Microcomputer (SCM) system 1; If not the electric degree transmitter, then road multi-way switch 14 and ripple detection circuit 18 are sent in its output; When the start key of pressing a certain interchange transmitter of automatic survey, then Single Chip Microcomputer (SCM) system 1 provides the frequency of one group of control three-phase supply immediately, the digital quantity of phase place and amplitude is given external program control three-phase supply 25, the required power supply of first test point of 25 output test transmitters, send three-phase power socket 2 to, by three-phase power socket 2 output two-way, one the tunnel is transferred to transmitter input and output socket 3, send tested interchange transmitter 23 to by transmitter input and output socket 3, another road sends mutual inductor 4 to, the output of mutual inductor 4 has four the tunnel, one the tunnel sends multi-way switch 5 to, one the tunnel sends multi-way switch 6 to, one the tunnel sends sample frequency automatic tracking circuit 20 to, pass to Single Chip Microcomputer (SCM) system 1 again, the one tunnel sends phase frequency test circuit 19 to, passes to Single Chip Microcomputer (SCM) system 1 again.Single Chip Microcomputer (SCM) system 1 goes to control multi-way switch 5 and 6 by controller 7 and 8, X, the Y end of analog multiplier 12 is passed in multi-way switch 5 and 6 output respectively by programmable amplifier 10 and 11, the output of analog multiplier 12 is passed to Single Chip Microcomputer (SCM) system 1 by low-channel filter 13, multi-way switch 14, amplifilter 16, A/D converter 17; When signal was passed to multi-way switch 14, Single Chip Microcomputer (SCM) system 1 sent channel address to multi-way switch 14 through controller 15; Reference power supply 9 outputs three tunnel, a tunnel are transferred to multi-way switch 5, and one the tunnel sends multi-way switch 6 to, and one the tunnel is transferred to multi-way switch 14; The millivolt step voltage of external programme-controlled dc power 24 outputs is transferred to weak signal and amplifies and control circuit 21, and multi-way switch 14 is passed in the output of weak signal amplification and control circuit 21; The volt step voltage that programme-controlled dc power 24 is sent, the one tunnel is transferred to transmitter input and output socket 3, sends tested direct current transmitter 23 again to, and the output that voltage divider 22, voltage divider 22 are passed in another road sends multi-way switch 14 to; The output of tested transmitter 23, the one tunnel sends multi-way switch 14 to, and one the tunnel is transferred to ripple detection circuit 18, also has one the tunnel to send Single Chip Microcomputer (SCM) system 1 to.

This invention principle of work is as follows: this instrument is mainly finished test and is adjusted the task of the various transmitters of verification, also can be used for test and the various ammeters of verification.Adjustment and the various transmitters of verification utilize each function key to finish.Its test philosophy is as follows: whole invention is to carry out in phase in order under Single Chip Microcomputer (SCM) system control, when semi-automatic mode is surveyed various interchange transmitter, and the frequency of programmable power supply output current, voltage, phase place and amplitude set by knob or keyboard; When automatic working method, provide one group of number by computer software and be provided with.After the various parameters of the good power supply of computer installation, the output of power supply sends the three-phase supply multi-tap to, deliver to tested interchange transmitter 23 input ends and mutual inductor through multi-tap, deliver to multi-way switch 5 and multi-way switch 6 again through mutual inductor, Single Chip Microcomputer (SCM) system is come the tested of ac of gating by controller 7 and 8.If the test Alternative Voltage Converter, elder generation surveys the effective value of its input voltage Uab, and then Single Chip Microcomputer (SCM) system is controlled all gating alternating voltage Uab of multi-way switch 5,6, sends into analog multiplier after amplifying, and multiplier is output as Ku _AbU _Ab=K $\sqrt{2}$ U _abcosωt· $\sqrt{2}$ U _AbCos ω t=KU ² _Ab-KU ² _AbCos2 ω t, K is a coefficient in the formula, second is AC compounent, with its filtering (comprising the secondary analog filtering, a digital filtering), just is left first DC voltage KU with low-pass filter ² _Ab, be converted into digital quantity, carry out extracting operation with Single Chip Microcomputer (SCM) system again, just can obtain real effective U _Ab.If survey the power input of various AC power transmitters, Single Chip Microcomputer (SCM) system just in batches each corresponding input quantity of gating AC power transmitter enter analog multiplier and multiply each other, its computing is that (1) is if survey two watts of method phase three-wire three active power P=P _A+ P _c, P _A=u _AbI _a= $\sqrt{2}$ U _ab·cosωt· $\sqrt{2}$ Iacos(ω t-Φ)=I _AU _AbCos Φ-I _AU _AbCos(2 ω t-Φ); P _c=U _CBI _cCos Φ-U _CBI _cCos(2 ω t-Φ), P _A, and P _CSecond in the formula is AC compounent, and with its filtering, remaining first DC component promptly is respectively P with low-pass filter _AAnd P _C(because of the mean value of AC compounent is 0), multiplier calculates P _A, P _CBy Single Chip Microcomputer (SCM) system by the corresponding amount of the gating realization of multiplying each other in batches of control multi-way switch.Ask P _A+ P _CCalculating finish by Single Chip Microcomputer (SCM) system.(2) three-phase and four-line of three watts of methods of survey has power and various reactive power, all be that formula according to correspondence calculates: corresponding two of acs are after analog multiplier multiplies each other, after filtering alternating component through low-pass filter 13 again, pass to multi-way switch 14, the output of single-chip microcomputer steering controller 15 gating low-pass filters 13, deliver to A/D converter again after delivering to amplifilter 16 amplification filtering, be converted to digital quantity and deposit Single Chip Microcomputer (SCM) system in, just can obtain the value of the input AC amount of transmitter through data processing.Each output quantity that is exchanged transmitter by the school is delivered to multi-way switch 14, controller 15 is each output quantity of gating respectively, through the amplifilter amplification filtering, give A/D converter, Single Chip Microcomputer (SCM) system is handled A/D converter and is sampled, and carries out data processing through Single Chip Microcomputer (SCM) system, can get the value of the output quantity of transmitter, Single Chip Microcomputer (SCM) system calculates the error of each output quantity of transmitter again, send display to demonstrate each input quantity, output quantity and the error thereof of transmitter simultaneously then.Can also send printer prints to go out form.Can test the direct current transmitter equally, different just direct current transmitters are to come by multi-way switch 14 that each input, the output quantity of gating transmitter are tested, calculate, shown and print respectively.The method of testing of frequency and power factor (PF) transmitter: Single Chip Microcomputer (SCM) system is controlled program control three-phase ac regulated power supply, after given frequency or the phase place, accurately measures phase place by the phase frequency test circuit again or frequency deposits the Single Chip Microcomputer (SCM) system internal memory in.Single Chip Microcomputer (SCM) system is measured the output of transmitter again, and calculates error, send display to demonstrate each input, output quantity and error thereof simultaneously, same printable form.Measurement to the input electric energy of watt-hour meter or electric degree transmitter, be to produce standard timing by Single Chip Microcomputer (SCM) system internal standard timer, be multiplied by again the calibration power of being surveyed finish (for fear of bringing error in test electric energy process because of the supply voltage electric current changes, thus be actually by $\underset{\mathrm{i=o}}{\overset{n}{\mathrm{\Σ}}}$ The formula of △ Pi △ t is tested the calculating electric energy).The output of electric degree transmitter is pulse, Single Chip Microcomputer (SCM) system is directly delivered in these pulses gone test and calculating.The working method of this invention test transmitter: two kinds of full rotation type and automanual systems are arranged.The fully automatic working mode is to click full-automatic mode key, Single Chip Microcomputer (SCM) system is controlled program control three-phase voltage-stabilizing power supply 25, provide the input electric weight of different test points successively by transmitter verification rule, test circuit is measured each input quantity and each output quantity of transmitter successively and is calculated its error, shows, prints each input, output quantity and error while surveying by certain format.Behind the clock, printer is sent a total data form by the test of verification rules more than 1 minute.The semi-automatic work mode is by each input quantity that manually sets transmitter on program control three-phase voltage-stabilizing power supply 25, automatically test and calculate the value of each input and output amount then by check meter, calculate the error of each output quantity, be simultaneously displayed on each display, equally also printing reports (whether print and can artificially control) automatically, semi-automatic mode also is a kind of most common form.Adjusting calibration transmitter all is to carry out under semi-automatic mode.

The present invention has compared with prior art realized miniaturization: its volume only is 410 * 380 * 150mm ³, weight is 12kg, intellectuality: the automatically calibrating scale-up factor, revise nonlinearity erron automatically, and eliminate zero drift automatically, can carry out automatically and each input quantity, each output quantity of the various transmitters of semi-automatic test verification and calculate the error of each output quantity; The precision height: entrust to economize electric power proof that testing research is tested through province Weights and Measures Bureau, the error of the various electric weight of this instrument test is generally ten thousand/, two, the base point error is 3/10000ths, four; Good stability; Measure through economizing the electric power testing research, test cross stream voltage temperature coefficient only is 3ppm/ ℃, temperature power coefficient also is 3ppm/ ℃, convenient and simple for operation, intuitive display: this instrument has four groups of 32 character codes to show, can show each input quantity of transmitter, each output quantity and error thereof simultaneously, and printable form.Function is many: this instrument hardware circuit is flexible, function is strong, software is abundant, thereby accomplished a multi-purpose instrument, can test and adjust verification combined-voltage, electric current, active power, reactive power, applied power, active electrical degree, idle electric degree, power factor (PF), various electric parameters transducers such as frequency also can be surveyed various ammeters, and can improve the precision of the transmitter that is adjusted verification.

Accompanying drawing 1 is a block diagram of the present invention

Now technical scheme is further described in conjunction with block diagram of the present invention.This invention is by Single Chip Microcomputer (SCM) system 1, three-phase power socket 2, the transmitter input, accessory power outlet 3, mutual inductor 4, multi-way switch 5 and 6, controller 7 and 8, reference power supply 9, programmable amplifier 10 and 11, analog multiplier 12, low-pass filter 13, multi-way switch 14, controller 15, amplifilter 16, A/D converter 17, ripple detection circuit 18, phase frequency test circuit 19, sample frequency automatic tracking circuit 20, weak signal is amplified and compositions such as control circuit 21 and voltage divider 22.This technical scheme connecting relation is as follows.

Whole technical proposal is to move under the Single Chip Microcomputer (SCM) system programmed control.Single Chip Microcomputer (SCM) system 1 by 8032 single-chip microcomputer a slices, two of 74LS245,74LS373 a slice, 74LS273 a slice, two of 74LS138,27256 a slices, 6264 a slices, 8,279 two, 74LS154 a slice, (every key all has upper and lower shelves function to 75,451 eight, 32 special function keys, wherein the key of minority also has three functions, click a certain key, the program of just carrying out this key and being determined.Various work of the present invention is all carried out under programmed control), 32 charactron tubes, a printer and a composition such as printer interface.Single Chip Microcomputer (SCM) system is amplified with external two power supplys, A/D converter 17, controller 7,8 and 15, weak signal respectively and the output of control circuit 21, programmable amplifier 10 and 11, tested transmitter 23, phase frequency test circuit 19, sample frequency automatic tracking circuit 20 etc. link.When the start key of pressing a certain interchange transmitter of automatic test, then Single Chip Microcomputer (SCM) system 1 provides the frequency of one group of control three-phase supply immediately, the digital quantity of phase place and amplitude, the required power supply of first test point of 25 output tests of external program control three-phase supply transmitter, sending model to is the three-phase power socket 2 of CA-20, model is the transmitter input and output socket 3 of CD1-51-K, pass to tested transmitter again, another road sends mutual inductor 4 to, mutual inductor 4 is made up of three voltage transformer (VT) and three current transformers, voltage transformer (VT) adopts D340 or the Z11 ring-shaped core of Φ 58/ Φ 36 * 30,0.06 volt of every circle, the input voltage on former limit has 120 volts, 100 volts and 60 volts of third gear are output as the voltage of one 3.5 volts or two 3.5 volts; Current transformer adopts IJ79 or the IJ85 ring-shaped core of Φ 58/ Φ 36 * 30, and primary current is 5 amperes, 1 ampere and 0.5 ampere of third gear, and output current is 20mA.Through one 175 ohm precision resistances the current conversion of 20mA is become 3.5 volts voltage, the former limit shelves level of this mutual inductor what and size all can design according to user's requirement, mutual inductor 4 outputs four tunnel, two-way wherein, send the multi-way switch 5 and 6 of serving as to by CD4067, carry out various combinations in order to output voltage, to finish the multifunctional testing task with mutual inductor; One the tunnel sends sample frequency automatic tracking circuit 20 to, this circuit is to be made of CD4046 and 74LS93, this circuit is actual to be the frequency multiplication of phase locked loop circuit, it goes out-put supply signal 32 frequencys multiplication, 64 frequencys multiplication or 128 frequencys multiplication of transmitter to control as 8032 monolithics the query ID of the sample frequency of A/D converter, so that when digital filtering, the interference of filtering and testing power supply same frequency and the alternating component in the direct current signal effectively, the output of sample frequency automatic tracking circuit 20 sends Single Chip Microcomputer (SCM) system 1 to; Also have one the tunnel to send phase frequency test circuit 19 to, pass to again Single Chip Microcomputer (SCM) system 1, phase frequency test circuit by LF354 make, enlargement factor is 10, bandwidth is that two timer counters in amplifier, zero-crossing comparator LM393,74LS125 and 8032 single-chip microcomputers of 0～10KH are formed, in order to phase place and the frequency between the defeated voltage and current of test transmitter.Single Chip Microcomputer (SCM) system 1 by form by 74LS373 and amplifier LM323 in order to latch the address code that Single Chip Microcomputer (SCM) system 1 is sent here, the controller 7 and 8 of the line level of going forward side by side conversion removes to control the multi-way switch 5 and 6 of being served as by CD4067, multi-way switch 5 and 6 output, send to respectively by operational amplifier A D517L and precision resistance, the linear precision of compositions such as general-purpose relay is 0.003% programmable amplifier 10 and 11, send the X of analog multiplier 12 again to, the Y end is in order to amplify the voltage of multi-way switch 5 and 6 outputs, the enlargement factor of program control amplification has 2,6,10 third gear, changed by the programmed control relay, to guarantee under small-signal the precision of whole test circuit.Analog multiplier 12 is that precision is 0.02%, and frequency band is the multiplier of 0～100KHz, the output of analog multiplier 12, and by by AD517L and resistance, the low-pass filter 13 that electric capacity is formed is passed to multi-way switch 14.The cutoff frequency of low-pass filter 13 is 20Hz, transfer coefficient is 1, in order to the alternating component in the filtered signal, multi-way switch 14 is served as by CD4067, the output of multi-way switch 14 transmits the amplifilter of being made up of AD517L and resistance, electric capacity 16, in order to the AC compounent in the further filtered signal.A/D converter 17 is passed in the output of amplifilter 16, and it is 0.012% that A/D converter adopts ADC80, precision, and Single Chip Microcomputer (SCM) system 1 is passed in the output of A/D converter.Before signal is passed to multi-way switch 14, Single Chip Microcomputer (SCM) system 1 with channel address through forming by LM324 and 74LS373 etc. and in order to control the controller 15 of multi-way switch 14.Reference power supply 9 is defeated to have 2 volts, 5 volts, 75 millivolts third gear, degree of stability to be ± 0.3PPm/ ℃, is used for the automatic ratio coefficient correction, and this power supply is exported three the tunnel, the one tunnel and is transferred to multi-way switch 5, and one the tunnel sends multi-way switch 6 to, and one the tunnel is transferred to multi-way switch 14.The millivolt step voltage of external programme-controlled dc power 24 outputs is transferred to weak signal and amplifies and control circuit 21, when surveying the transmitter of 75 volts of direct currents, 0～75 millivolt tested DC voltage must be amplified 66.6 times through the weak signal amplifier, obtaining 5 volts voltage transmits and send multi-way switch 14, the weak signal amplifying circuit is made up of AD517L and resistance etc., has adopted the control circuit of being made up of multi-way switch CD4052 and LM324,74LS373 etc. for what the weak signal amplifier is carried out scale-up factor and zero-bit from normal moveout correction.Come the completed percentage coefficient correction by program, the output signal work of the straight transmitter stream of zero correction and test.Weak signal is amplified and multi-way switch 14 is passed in the output of control circuit 21.The voltage of the volt level of external power supply sends transmitter input and output socket 3 and voltage divider 22 to.Owing to 75 millivolts, 50 volts, 150 volts, 200 volts, 300 volts, 450 volts, 500 volts and 600 volts etc. grade grade are arranged by the input voltage of direct current transmitter 23, wherein 75 millivolts voltage need become its amplification 5 volts voltage through the weak signal amplifier, deliver to multi-way switch 14 again, remaining voltage is 5 volts through the voltage divider step-down then, deliver to multi-way switch 14 again, its dividing potential drop coefficient is 1/10,1/30 ... 1/120.The input resistance of voltage divider is 45K when 50 volts of shelves, and other shelves are followed successively by 145K, 195K, 245K, 445K and 595K.The output of tested transmitter, one the tunnel sends multi-way switch 14 to, one the tunnel is transferred to ripple detection circuit 18, this circuit is in order to amplify the alternating component in various transmitter outputs and DC voltage, the electric current, so it is the interchange low-frequency amplifier that partiting dc capacitor is arranged, the ripple voltage in the output of its output and tested transmitter is directly proportional, and do not contain flip-flop, the enlargement factor of low-frequency amplifier is 50, and frequency band is 10～50KH, and linear precision is 0.1%.

Claims (2)

1, the check meter of a kind of electric parameters transducer and ammeter, it comprises monolithic system 1, A/D converter 17, programmable amplifier 10 and 11, it is characterized in that it also comprises three-phase power socket 2, the transmitter input, accessory power outlet 3, mutual inductor 4, multi-way switch 5 and 6, controller 7 and 8, reference power supply 9, analog multiplier 12, low-pass filter 13, multi-way switch 14, controller 15, amplifilter 16, ripple detection circuit 18, phase frequency test circuit 19, sample frequency automatic tracking circuit 20, weak signal is amplified and compositions such as control circuit 21 and voltage divider 22, and the connecting relation of this technical scheme is as follows: Single Chip Microcomputer (SCM) system 1, respectively with external two power supplys 24,25, A/D converter 17, controller 7,8 and 15, weak signal is amplified and control circuit 21, programmable amplifier 10 and 11, phase frequency test circuit 19, sample frequency automatic tracking circuit 20 links; If tested transmitter is the electric degree transmitter, then its output pulse direct sending is gone into Single Chip Microcomputer (SCM) system 1; If not the electric degree transmitter, then multi-way switch 14 and ripple detection circuit 18 are sent in its output; When the start key of pressing a certain interchange transmitter of automatic survey, then Single Chip Microcomputer (SCM) system 1 provides the frequency of one group of control three-phase supply immediately, the digital quantity of phase place and amplitude, give external program control three-phase supply 25, the required power supply of first test point of 25 output test transmitters, send three-phase power socket 2 to, by three-phase power socket 2 output two-way, one the tunnel is transferred to transmitter input and output socket 3, send tested interchange transmitter 23 to by transmitter input and output socket 3, another road sends mutual inductor 4 to, the output of mutual inductor 4 has four the tunnel, the one tunnel to send multi-way switch 5 to, and one the tunnel sends multi-way switch 6 to, one the tunnel sends sample frequency automatic tracking circuit 20 to, pass to Single Chip Microcomputer (SCM) system 1 again, the one tunnel sends phase frequency test circuit 19 to, passes to Single Chip Microcomputer (SCM) system 1 again.Single Chip Microcomputer (SCM) system 1 goes to control multi-way switch 5 and 6 by controller 7 and 8, X, the Y end of analog multiplier 12 is passed in multi-way switch 5 and 6 output respectively by programmable amplifier 10 and 11, the output of analog multiplier 12 is passed to Single Chip Microcomputer (SCM) system 1 by low-channel filter 13, multi-way switch 14, amplifilter 16, A/D converter 17; When signal was passed to multi-way switch 14, Single Chip Microcomputer (SCM) system 1 sent channel address to multi-way switch 14 through controller 15; Reference power supply 9 outputs three tunnel, a tunnel are transferred to multi-way switch 5, and one the tunnel is transferred to multi-way switch 6, and one the tunnel is transferred to multi-way switch 14; The millivolt step voltage of external programme-controlled dc power 24 outputs is transferred to weak signal amplification and control circuit 21, weak signal is amplified and the output of control circuit 21, passes to multi-way switch 14; The volt step voltage that programme-controlled dc power 24 is sent, one the tunnel is transferred to transmitter input and output socket 3, send tested direct current transmitter 23 again to, the output that voltage divider 22, voltage divider 22 are passed in another road sends multi-way switch 14 to, the output of tested transmitter 23, one the tunnel sends multi-way switch 14 to, and one the tunnel is transferred to ripple detection circuit 18, also has one the tunnel to send Single Chip Microcomputer (SCM) system 1 to.

2, the check meter of electric parameters transducer according to claim 1 and ammeter is characterized in that mutual inductor 4 is made up of three voltage transformer (VT) and three current transformers.

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