CN213986674U - Transformer characteristic and capacity tester capable of improving working efficiency - Google Patents
Transformer characteristic and capacity tester capable of improving working efficiency Download PDFInfo
- Publication number
- CN213986674U CN213986674U CN202023024801.1U CN202023024801U CN213986674U CN 213986674 U CN213986674 U CN 213986674U CN 202023024801 U CN202023024801 U CN 202023024801U CN 213986674 U CN213986674 U CN 213986674U
- Authority
- CN
- China
- Prior art keywords
- transformer
- operational amplifier
- att7022b
- voltage
- capacitor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
The utility model provides a can improve work efficiency's transformer characteristic and capacity tester, including current transformer, voltage transformer, anti-aliasing circuit, ATT7022B module and singlechip, the anti-aliasing circuit is active low pass filter. The utility model discloses an anti-aliasing circuit adopts active low pass filter, and the voltage of output is faster at the falling speed of high frequency section, can improve the filter effect, and relative first-order low pass RC filter circuit's filter effect is better, is favorable to improving transformer characteristic and capacity test's precision.
Description
Technical Field
The utility model relates to a transformer characteristic and capacity test technical field especially relate to a can improve work efficiency's transformer characteristic and capacity tester.
Background
The transformer characteristic and capacity tester can accurately measure the capacity of various distribution transformers, and can be used for passive measurement, and can be used for measuring the no-load current, no-load loss, short-circuit voltage, short-circuit loss and zero-sequence impedance of various transformers, and can also be used for automatically carrying out waveform distortion correction, temperature correction, voltage correction (no-load test under non-rated voltage) and current correction (short-circuit test under non-rated current), and an operator can automatically calculate the corrected result only by inputting a correction index instrument according to the type of the transformer, so that external voltage is allowed, and the current transformer can be used for measuring the tested article with any parameter by extending the measuring range.
The transformer characteristic and capacity tester mostly measures three-phase voltage and current through a current transformer and a voltage transformer, then a single chip microcomputer calculates and obtains transformer capacity, no-load and load characteristic parameters according to the three-phase voltage and current, and the type of the transformer is obtained through a table look-up algorithm. Considering the actual sampling condition of the system to the analog signal, the access of the voltage transformer and the current transformer can also affect the sampling signal, so that signals of various frequency spectrums are mixed in the signals to be acquired, many of the frequency spectrum signals are signals which are not needed by the system, and anti-aliasing filtering is required to be performed through a low-pass filter. Most of the traditional transformer characteristic and capacity testers pass through passive RC filtering, the filtering effect is poor, and the precision of transformer characteristic and capacity testing is reduced.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a can improve work efficiency's transformer characteristic and capacity tester to solve traditional transformer characteristic and capacity tester and carry out the poor problem of effect of anti-aliasing through passive RC filtering.
The technical scheme of the utility model is realized like this: a transformer characteristic and capacity tester capable of improving working efficiency comprises a current transformer, a voltage transformer, an anti-aliasing circuit, an ATT7022B module and a single chip microcomputer, wherein the anti-aliasing circuit is an active low-pass filter;
the current transformer and the voltage transformer are respectively used for collecting three-phase current and three-phase voltage of a transformer test, the output ends of the current transformer and the voltage transformer are respectively connected with the analog input end of the ATT7022B module through an active low-pass filter, and the ATT7022B module is connected with the single chip microcomputer through an SPI bus.
Optionally, the ATT7022B module includes the ATT7022B chip itself and its peripheral circuits.
Optionally, the active low-pass filter includes an operational amplifier U1, resistors R1 to R2, and capacitors C1 to C2;
the output end of the current transformer or the voltage transformer is connected with the output end of an operational amplifier U1 through a resistor R1 and a capacitor C1 in sequence, the output end of the operational amplifier U1 is further connected with the inverting end of the operational amplifier U1, the common end of the resistor R1 and the common end of the capacitor C1 are grounded through a resistor R2 and a capacitor C2 in sequence, the common end of the resistor R2 and the common end of the capacitor C2 are connected with the inverting end of the operational amplifier U1, and the output end of the operational amplifier U1 is connected with the analog input end of an ATT7022B chip.
Optionally, the active low-pass filter further includes an operational amplifier U2, resistors R3 to R4, and capacitors C3 to C4, and the operational amplifier U2, the resistors R3 to R4, and the capacitors C3 to C4 are connected between the output end of the operational amplifier U1 and the analog input end of the ATT7022B chip;
the output end of the operational amplifier U1 is further connected with the output end of the operational amplifier U2 through a resistor R3 and a capacitor C3 in sequence, the output end of the operational amplifier U2 is further connected with the inverting end of the operational amplifier U2, the common end of the resistor R3 and the capacitor C3 is grounded through the resistor R4 and the capacitor C4 in sequence, the common end of the resistor R4 and the capacitor C4 is connected with the inverting end of the operational amplifier U2, and the output end of the operational amplifier U2 is connected with the analog input end of the ATT7022B chip.
Optionally, the transformer characteristic and capacity tester capable of improving the working efficiency further comprises a voltage follower, and the voltage follower is connected between the current transformer and the anti-aliasing circuit, and between the voltage transformer and the anti-aliasing circuit.
Optionally, the single chip microcomputer includes a C8051F360 chip and a peripheral circuit thereof.
Optionally, the transformer characteristic and capacity tester capable of improving the working efficiency further comprises a liquid crystal display module, and the liquid crystal display module is connected with the single chip microcomputer through an RS232 interface.
The utility model discloses a transformer characteristic and capacity tester has following beneficial effect for prior art:
(1) the anti-aliasing circuit adopts an active low-pass filter, the output voltage has higher descending speed in a high-frequency section, the filtering effect can be improved, and the anti-aliasing circuit has better filtering effect compared with a first-order low-pass RC filtering circuit, and is beneficial to improving the transformer characteristic and the capacity testing precision.
(2) The special metering chip ATT7022B is adopted to directly extract the analog output of the current transformer and the voltage transformer and convert the analog output into a current voltage effective value, the measuring accuracy is high, the structure is simple, the development cost is low, the period is short, and the working efficiency of the instrument can be improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a block diagram of a transformer characteristic and capacity tester according to the present invention;
fig. 2 is a circuit diagram of the anti-aliasing circuit of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work all belong to the protection scope of the present invention.
As shown in fig. 1, the transformer characteristic and capacity tester capable of improving the working efficiency of the present embodiment includes a current transformer, a voltage transformer, an anti-aliasing circuit, an ATT7022B module, and a single chip microcomputer. The anti-aliasing circuit is an active low-pass filter, the current transformer and the voltage transformer are respectively used for collecting three-phase current and three-phase voltage of the transformer test, the output ends of the current transformer and the voltage transformer are respectively connected with the analog input end of the ATT7022B module through the active low-pass filter, and the ATT7022B module is connected with the single chip microcomputer through the SPI bus. The ATT7022B module comprises an ATT7022B chip and peripheral circuits thereof, and the singlechip comprises a C8051F360 chip and peripheral circuits thereof.
In this embodiment, the current transformer and the voltage transformer have three paths, and respectively collect three-phase current and three-phase voltage tested by the transformer. For an electronic transformer comprising digital data transmission, the highest frequency fa that it can measure and transmit correctly, the so-called frequency bandwidth, should be considered. fa is typically half the output data rate used. The frequency bandwidth of the transformer is determined by the sampling rate fs and the data rate fdr. When fs is greater than fdr, fa is fdr/2; when fs < fdr, fa ═ fs/2. If a plurality of data rates are adopted in the transmission path, the lowest frequency of the data rates determines the bandwidth of the transformer. The IEC standard specifies that in order to ensure the accuracy of the electronic transformer, the design of the anti-aliasing circuit should satisfy: when f is more than or equal to 2fa-fr, the attenuation is more than or equal to 40 dB. In addition to the above mentioned attenuation requirements, in the data acquisition process, high frequency interference signals are inevitably mixed in the output signals, and in order to suppress or eliminate the influence of aliasing phenomenon on data acquisition to the maximum extent, it is necessary to attenuate and filter unwanted signals by using an anti-aliasing circuit.
As shown in fig. 2, the active low-pass filter of this embodiment includes an operational amplifier U1, resistors R1 to R2, capacitors C1 to C2, and output terminals of the current transformer or the voltage transformer are sequentially connected to an output terminal of the operational amplifier U1 through a resistor R1 and a capacitor C1, an output terminal of the operational amplifier U1 is further connected to an inverting terminal of the operational amplifier U1, a common terminal of the resistor R1 and the capacitor C1 is sequentially grounded through the resistor R2 and the capacitor C2, a common terminal of the resistor R2 and the capacitor C2 is connected to a non-inverting terminal of the operational amplifier U1, and an output terminal of the operational amplifier U1 is connected to an analog input terminal of the ATT7022B chip. The operational amplifier U1, the resistors R1-R2 and the capacitors C1-C2 form an active second-order voltage-controlled low-pass filter circuit, so that the output voltage is reduced at a high-frequency section more quickly, the filter effect can be improved, and the filter effect is better compared with that of a first-order low-pass filter circuit. In the filter circuit, a capacitor C1 is connected to the output end of the filter circuit to form positive feedback of the integrated operational amplifier, and C1-C2-C enable the whole circuit to have positive feedback and not to generate self-oscillation near a cut-off frequency f0, the voltage gain of the filter near f0 is improved, and logarithmic amplitude-frequency characteristics are relatively close to ideal horizontal lines. For convenience of calculation, R1 ═ R2 ═ R, f0 ═ 1/(2 pi RC).
Further, as shown in fig. 2, in this embodiment, it is preferable that the active low pass filter further includes an operational amplifier U2, resistors R3 to R4, and capacitors C3 to C4, and the operational amplifier U2, the resistors R3 to R4, and the capacitors C3 to C4 are connected between the output terminal of the operational amplifier U1 and the analog input terminal of the ATT7022B chip. The output end of the operational amplifier U1 is further connected with the output end of the operational amplifier U2 through a resistor R3 and a capacitor C3 in sequence, the output end of the operational amplifier U2 is further connected with the inverting end of the operational amplifier U2, the common end of the resistor R3 and the capacitor C3 is grounded through the resistor R4 and the capacitor C4 in sequence, the common end of the resistor R4 and the capacitor C4 is connected with the inverting end of the operational amplifier U2, and the output end of the operational amplifier U2 is connected with the analog input end of the ATT7022B chip. The operational amplifier U1, the resistors R1-R2, the capacitors C1-C2, the operational amplifier U2, the resistors R3-R4 and the capacitors C3-C4 form a fourth-order Bessel filter, and the calculation mode of the cut-off frequency f0 is different from that of the active second-order voltage-controlled low-pass filter circuit, and is not described again here. The bessel filter has the following advantages: excellent transient response, no overshoot and short reduction time; the attenuation of frequencies higher than the data rate is reasonable; the group delay in the coverage broadband is constant, namely for signals with different frequencies in the passband, the phase shift introduced by the group delay is a linear function of the cut-off frequency Z; the filter has the same effect on the phase shift as the pure delay in the transmission system, and thus has a negligible effect on the phase shift as long as its equivalent delay time is contained within the nominal delay time of the ECT. Equivalent delay time equals 1.01/data rate: with the flattest amplitude and phase shifts, the phase response of the bandpass is nearly linear; can be used to reduce the inherent nonlinear phase distortion of all IIR filters.
In the embodiment, a professional metering chip ATT7022B is adopted to directly extract analog outputs of a current transformer and a voltage transformer and convert the analog outputs into a current voltage effective value, a 7-path 16-bit second-order sigma-delta ADC is integrated in an ATT7022B analog-to-digital conversion unit, voltage and current sampling is three paths, a digital signal processing circuit (DSP) is arranged in the converter, precision parameters of the voltage and current effective values are superior to 0.5%, the measurement accuracy is high, the structure is simple, the development cost is low, the period is short, and the working efficiency of the instrument can be improved.
As shown in fig. 1, the transformer characteristic and capacity tester of the present embodiment further includes a voltage follower, and the voltage follower is connected between the current transformer and the anti-aliasing circuit, and between the voltage transformer and the anti-aliasing circuit. In a circuit, voltage followers are commonly used as isolation stages and buffer stages. Since the output impedance of the voltage amplifier is usually high, typically from several kilohms to several tens of kilohms, if the input impedance of the subsequent stage is relatively low, a large portion of the signal is lost in the output circuit of the previous stage. Therefore, a voltage follower is required for buffering, and the effect of starting and stopping can be achieved. Another advantage of using a voltage follower is that the input impedance can be increased, for which reason the capacity of the input capacitor can be reduced considerably, providing a prerequisite for the use of high-quality capacitors.
As shown in fig. 1, the transformer characteristic and capacity tester of the present embodiment further includes a liquid crystal display module, the liquid crystal display module is connected to the single chip microcomputer through an RS232 interface for displaying measurement parameters, and the type of the liquid crystal display module may be DMT80600T080_18 WT. When the single chip microcomputer is connected with a 232 serial port, a TTL-to-RS-232 level conversion circuit is needed, and a level conversion chip MAX232 can be used in the embodiment.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A transformer characteristic and capacity tester capable of improving working efficiency comprises a current transformer, a voltage transformer, an anti-aliasing circuit, an ATT7022B module and a single chip microcomputer, and is characterized in that the anti-aliasing circuit is an active low-pass filter;
the current transformer and the voltage transformer are respectively used for collecting three-phase current and three-phase voltage of a transformer test, the output ends of the current transformer and the voltage transformer are respectively connected with the analog input end of the ATT7022B module through an active low-pass filter, and the ATT7022B module is connected with the single chip microcomputer through an SPI bus.
2. The transformer characteristic and capacity tester capable of improving operation efficiency as claimed in claim 1, wherein the ATT7022B module comprises the ATT7022B chip itself and its peripheral circuits.
3. The transformer characteristic and capacity tester capable of improving operation efficiency as claimed in claim 2, wherein the active low pass filter includes an operational amplifier U1, resistors R1-R2 and capacitors C1-C2;
the output end of the current transformer or the voltage transformer is connected with the output end of an operational amplifier U1 through a resistor R1 and a capacitor C1 in sequence, the output end of the operational amplifier U1 is further connected with the inverting end of the operational amplifier U1, the common end of the resistor R1 and the common end of the capacitor C1 are grounded through a resistor R2 and a capacitor C2 in sequence, the common end of the resistor R2 and the common end of the capacitor C2 are connected with the inverting end of the operational amplifier U1, and the output end of the operational amplifier U1 is connected with the analog input end of an ATT7022B chip.
4. The transformer characteristic and capacity tester capable of improving the working efficiency as claimed in claim 3, wherein the active low pass filter further comprises an operational amplifier U2, resistors R3-R4 and capacitors C3-C4, the operational amplifier U2, the resistors R3-R4 and the capacitors C3-C4 are connected between the output end of the operational amplifier U1 and the analog input end of the ATT7022B chip;
the output end of the operational amplifier U1 is further connected with the output end of the operational amplifier U2 through a resistor R3 and a capacitor C3 in sequence, the output end of the operational amplifier U2 is further connected with the inverting end of the operational amplifier U2, the common end of the resistor R3 and the capacitor C3 is grounded through the resistor R4 and the capacitor C4 in sequence, the common end of the resistor R4 and the capacitor C4 is connected with the inverting end of the operational amplifier U2, and the output end of the operational amplifier U2 is connected with the analog input end of the ATT7022B chip.
5. The transformer characteristic and capacity tester capable of improving the working efficiency as claimed in claim 1, further comprising a voltage follower, wherein the voltage follower is connected between the current transformer and the anti-aliasing circuit, and between the voltage transformer and the anti-aliasing circuit.
6. The transformer characteristic and capacity tester capable of improving work efficiency as claimed in claim 1, wherein the one-chip microcomputer includes a C8051F360 chip and its peripheral circuits.
7. The transformer characteristic and capacity tester capable of improving working efficiency as claimed in claim 1, further comprising a liquid crystal display module, wherein the liquid crystal display module is connected to the single chip microcomputer through an RS232 interface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023024801.1U CN213986674U (en) | 2020-12-16 | 2020-12-16 | Transformer characteristic and capacity tester capable of improving working efficiency |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202023024801.1U CN213986674U (en) | 2020-12-16 | 2020-12-16 | Transformer characteristic and capacity tester capable of improving working efficiency |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN213986674U true CN213986674U (en) | 2021-08-17 |
Family
ID=77243679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202023024801.1U Active CN213986674U (en) | 2020-12-16 | 2020-12-16 | Transformer characteristic and capacity tester capable of improving working efficiency |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN213986674U (en) |
-
2020
- 2020-12-16 CN CN202023024801.1U patent/CN213986674U/en active Active
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3565705B2 (en) | Measurement front end for a measurement device and method for obtaining a plurality of measurement parameters from a signal voltage | |
| CN104122444B (en) | All-digital IF spectrum analyzer and frequency spectrum analysis method | |
| CN107666300B (en) | Signal filtering processing comparison system based on analog-to-digital converter | |
| CN214041554U (en) | Wide digital ground resistance tester of application scope | |
| EP3884285B1 (en) | Mutual inductance-type current sensing | |
| CN111398662A (en) | Current sensor for power transmission line | |
| CN213986674U (en) | Transformer characteristic and capacity tester capable of improving working efficiency | |
| CN111880052A (en) | Hand-held type partial discharge detection device based on bluetooth interconnection terminal cluster | |
| CN115276661A (en) | Ultrahigh resolution analog-to-digital converter | |
| CN207399155U (en) | Signal filtering process Compare System based on analog-digital converter | |
| CN111338272A (en) | Differential multichannel high-voltage sampling circuit with second-order low-pass filtering | |
| CN209559967U (en) | A kind of current signal detecting device | |
| CN212845568U (en) | Current sampling circuit for remote transmission type fault indicator | |
| CN210514514U (en) | Small signal acquisition circuit applied to power distribution terminal | |
| CN108037359A (en) | A kind of grid frequency measurement circuit for eliminating flickering and m-Acetyl chlorophosphonazo interference | |
| CN212229025U (en) | Current sensor for power transmission line | |
| CN211930618U (en) | Analog front-end conditioning circuit of intelligent low-voltage shunt monitoring unit | |
| EP3933367A1 (en) | Sensor interface circuit, sensor system, and method of signal measurement | |
| CN208432658U (en) | A kind of electric energy meter and its AFE(analog front end) meeting IR46 standard | |
| CN113884963A (en) | High-precision direct-current standard electric energy meter | |
| CN218243488U (en) | Anti-aliasing filter circuit in industrial internet signal acquisition | |
| CN211506235U (en) | Differential multichannel high-voltage sampling circuit with second-order low-pass filtering | |
| CN218584881U (en) | Three-phase four-wire electric energy metering circuit and electric energy meter | |
| Lambrechts et al. | Active High Pass Filter for the Measurement of Supraharmonics | |
| CN200989920Y (en) | Electric energy quality tester signal dispensable circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant |