CN210572422U - Input circuit of AC pincerlike meter - Google Patents
Input circuit of AC pincerlike meter Download PDFInfo
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- CN210572422U CN210572422U CN201920982127.6U CN201920982127U CN210572422U CN 210572422 U CN210572422 U CN 210572422U CN 201920982127 U CN201920982127 U CN 201920982127U CN 210572422 U CN210572422 U CN 210572422U
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- 230000003321 amplification Effects 0.000 claims abstract description 11
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 11
- 239000003990 capacitor Substances 0.000 claims description 20
- 238000005259 measurement Methods 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
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Abstract
The utility model relates to an input circuit of exchanging pincerlike meter, including binding clip coil, load resistance, calibration circuit, first operational amplifier circuit, second operational amplifier circuit and range selection switch. When measuring current, the current induced by the clamp head coil generates voltage at two ends of the load resistor, the voltage is divided by the calibration circuit, the value of the output voltage can be changed by adjusting the adjustable resistor in the calibration circuit so as to obtain the required calibration voltage, if the current is large, the original output can be selected by the range selection switch, and if the current is small, the current is processed by the operational amplification circuit and then is output. Through the utility model discloses an input circuit of exchanging pincerlike meter when measuring undercurrent, can obtain less relative value error to the range of broad can be accomplished to the messenger exchanges pincerlike meter.
Description
Technical Field
The utility model relates to an input circuit of exchanging pincerlike meter belongs to electric current pincerlike meter technical field.
Background
The clamp-on meter is an instrument integrating a current transformer and an ammeter, is an important branch of a digital multimeter, and has the same working principle as the current measurement of the current transformer. The split core type ammeter is formed by combining a current transformer and an ammeter. The iron core of the current transformer can be opened when the wrench is tightened; the lead through which the current to be measured passes can pass through the open notch of the iron core without being cut off, and the iron core is closed after the wrench is released. The circuit conductor under test passing through the core becomes the primary coil of the current transformer, where the passage of current induces a current in the secondary coil. So that the ammeter connected with the secondary coil can indicate to measure the current of the measured circuit.
The input circuit of the AC clamp meter commonly used in the market at present uses a load resistor with larger resistance value to be connected in parallel with the secondary coil of the clamp head, the current induced by the secondary coil of the clamp head generates voltage drop through the load resistor when measuring the current, and the measured current value is displayed on the liquid crystal display after the voltage drop is converted by a rectifying circuit and A/D. According to a calculation formula of the relative value error of the clamp head circuit, the load resistance of the clamp head is in direct proportion to the relative value error, the higher the load resistance is, the lower the measurement accuracy is, and particularly the measurement accuracy of a small current range is not always required.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem, the utility model provides an input circuit of exchanging pincerlike meter improves the precision to the undercurrent range measurement.
The technical scheme of the utility model as follows:
an input circuit of an ac clamp meter, comprising: the clamp head coil L1, the load resistance R1, the calibration circuit 1, the first operational amplifier circuit 2, the second operational amplifier circuit 3 and the range selection switch K1, the load resistance R1 and the clamp head coil L1, the calibration circuit 1 connects in parallel, wherein:
the clamp coil L1 senses the measuring current and the calibration circuit 1 divides the input voltage, and the range selection switch K1 includes three input terminals, a first input terminal D1, a second input terminal D2, a third input terminal D3, and an output terminal N1.
The adjustable resistor VR1 in the calibration circuit 1 changes the value of the output voltage and outputs the output voltage through the input end selected by the range selection switch K1 in three ways, wherein the first way is directly input through a first input end D1; the second path is that the input voltage signal is amplified by the first operational amplifier circuit 2 and then output to a second input end D2; the third path is that the input voltage signal is amplified by the second operational amplifier circuit 3 and then output to the third input end D3.
One end of the load resistor R1, which is connected with the tong head coil L1 in parallel, is connected with a COM end.
The calibration circuit 1 comprises the variable resistor VR1 and a resistor R2 which are connected in series, and the series connection midpoint of the variable resistor VR1 and the resistor R2 is connected with three input ends, namely a first input end D1 of the range selection switch K1, an input end of the first operational amplification circuit 2 and an input end of the second operational amplification circuit 3.
The first operational amplifier circuit 2 is composed of an operational amplifier U1A, a resistor R3, a resistor R4 and a capacitor C1, wherein one end of the resistor R4 is connected to the negative input terminal of the operational amplifier U1A, the other end of the resistor R4 is connected to the output terminal of the operational amplifier U1A, one end of the resistor R3 is connected to the negative input terminal of the operational amplifier U1A, the other end of the resistor R3 is connected to the COM terminal, one end of the capacitor C1 is connected to the output terminal of the operational amplifier U1A, and the other end of the capacitor C1 is connected to the second input terminal D2 of the span selection switch K1.
The second operational amplifier circuit 3 is composed of an operational amplifier U1B, a resistor R5, a resistor R6 and a capacitor C2, wherein one end of the resistor R6 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R6 is connected to the output terminal of the operational amplifier U1B, one end of the resistor R5 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R5 is connected to the COM terminal, one end of the capacitor C2 is connected to the output terminal of the operational amplifier U1B, and the other end of the capacitor C2 is connected to the third input terminal D3 of the span selection switch K1.
The utility model discloses following beneficial effect has:
1. the range variable switch is arranged, and the metering range is wide;
2. when small current is measured, a small relative value error can be obtained.
Drawings
Fig. 1 is a circuit diagram of an embodiment of an input circuit of an ac clamp meter according to the present invention.
The reference numbers in the figures denote:
1-calibration circuit, 2-first operational amplifier circuit, 3-second operational amplifier circuit, L1-tong head coil L1, R1-load resistor R1, VR 1-variable resistor VR1, R2-resistor R2, U1A-operational amplifier U1A, R3-resistor R3, R4-resistor R4, C1-capacitor C1, U1B-operational amplifier U1B, R5-resistor R5, R6-resistor R6, C2-capacitor C2, K2-range selection switch K2, D2-range selection switch K2 first input end D2, D2-range selection switch K2 second input end D2, D2-range selection switch K2 third input end D2, N2-range selection switch K2N 2.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Example one
As shown in fig. 1, an input circuit of an ac clamp meter includes: the clamp head coil L1, the load resistance R1, the calibration circuit 1, the first operational amplifier circuit 2, the second operational amplifier circuit 3 and the range selection switch K1, the load resistance R1 and the clamp head coil L1, the calibration circuit 1 connects in parallel, wherein:
the clamp coil L1 senses the measuring current and the calibration circuit 1 divides the input voltage, and the range selection switch K1 includes three input terminals, a first input terminal D1, a second input terminal D2, a third input terminal D3, and an output terminal N1.
The adjustable resistor VR1 in the calibration circuit 1 changes the value of the output voltage and outputs the output voltage through the input end selected by the range selection switch K1 in three ways, wherein the first way is directly input through a first input end D1; the second path is that the input voltage signal is amplified by the first operational amplifier circuit 2 and then output to a second input end D2; the third path is that the input voltage signal is amplified by the second operational amplifier circuit 3 and then output to the third input end D3.
One end of the load resistor R1, which is connected with the tong head coil L1 in parallel, is connected with a COM end.
The calibration circuit 1 comprises the variable resistor VR1 and a resistor R2 which are connected in series, and the series connection midpoint of the variable resistor VR1 and the resistor R2 is connected with three input ends, namely a first input end D1 of the range selection switch K1, an input end of the first operational amplification circuit 2 and an input end of the second operational amplification circuit 3.
The first operational amplifier circuit 2 is composed of an operational amplifier U1A, a resistor R3, a resistor R4 and a capacitor C1, wherein one end of the resistor R4 is connected to the negative input terminal of the operational amplifier U1A, the other end of the resistor R4 is connected to the output terminal of the operational amplifier U1A, one end of the resistor R3 is connected to the negative input terminal of the operational amplifier U1A, the other end of the resistor R3 is connected to the COM terminal, one end of the capacitor C1 is connected to the output terminal of the operational amplifier U1A, and the other end of the capacitor C1 is connected to the second input terminal D2 of the span selection switch K1.
The second operational amplifier circuit 3 is composed of an operational amplifier U1B, a resistor R5, a resistor R6 and a capacitor C2, wherein one end of the resistor R6 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R6 is connected to the output terminal of the operational amplifier U1B, one end of the resistor R5 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R5 is connected to the COM terminal, one end of the capacitor C2 is connected to the output terminal of the operational amplifier U1B, and the other end of the capacitor C2 is connected to the third input terminal D3 of the span selection switch K1.
The measuring range selecting switch K1 is used for selecting measuring range, and the measured current value is displayed on the liquid crystal display after the output of the pin N1 is processed by the rectifying circuit and the A/D conversion.
In order to reduce the measurement relative value error, the load resistor R1 with a smaller resistance value is connected in parallel with the tong-head coil L1, the measurement induced current of the tong-head coil L1 generates a smaller voltage drop at the resistor R1, the voltage is divided by the adjustable resistor VR1 and the resistor R2, the adjustable resistor VR1 is adjusted to change the value of the output voltage to obtain the required calibration voltage, if the current is a large current, the input of the first input end D1 is selected directly through the path selection switch K1, the output is performed from the pin N1, if the current is a small current, the input of the second input end D2 or the third input end D3 of the path selection switch K1 after the operation amplification is performed through the first operation amplification circuit 2 or the second operation amplification circuit 3 according to the specific current requirement, and the output is performed from the output end N1. The first operational amplifier circuit 2 and the second operational amplifier circuit 3 have different amplification factors and different corresponding optimal measurement ranges.
The utility model discloses an input circuit of exchanging pincerlike meter when measuring undercurrent, can obtain less relative value error to the range of broad can be accomplished to the messenger exchanges pincerlike meter.
The above only is the embodiment of the present invention, not limiting the patent scope of the present invention, all the equivalent structures or equivalent processes that are used in the specification and the attached drawings or directly or indirectly applied to other related technical fields are included in the same way in the patent protection scope of the present invention.
Claims (5)
1. An input circuit of an ac clamp meter, comprising: the clamp head coil L1, the load resistance R1, the calibration circuit (1), the first operational amplifier circuit (2), the second operational amplifier circuit (3) and the range selection switch K1, the load resistance R1 is connected with the clamp head coil L1 and the calibration circuit (1) in parallel, wherein:
a measuring current is induced by the tong coil L1, and an input voltage is divided by the calibration circuit (1), the range selection switch K1 comprises three input ends, namely a first input end D1, a second input end D2, a third input end D3 and an output end N1;
the adjustable resistor VR1 in the calibration circuit (1) changes the value of the output voltage and outputs the output voltage in three paths through the input end selected by the range selection switch K1, and the first path is directly input through a first input end D1; the second path is that the input voltage signal is amplified by the first operational amplifier circuit (2) and then output to a second input end D2; and the third path is that the input voltage signal is amplified by the second operational amplifier circuit (3) and then output to a third input end D3.
2. An input circuit of an ac clamp meter according to claim 1, wherein: one end of the load resistor R1, which is connected with the tong head coil L1 in parallel, is connected with a COM end.
3. An input circuit of an ac clamp meter according to claim 2, wherein: the calibration circuit (1) comprises the adjustable resistor VR1 and a resistor R2 which are connected in series, the series midpoint of the adjustable resistor VR1 and the resistor R2 is connected with three input ends, namely a first input end D1 of the range selection switch K1, an input end of the first operational amplification circuit (2) and an input end of the second operational amplification circuit (3).
4. An input circuit of an ac clamp meter as claimed in claim 3, wherein: the first operational amplifier circuit (2) is composed of an operational amplifier U1A, a resistor R3, a resistor R4 and a capacitor C1, wherein one end of the resistor R4 is connected to the negative input end of the operational amplifier U1A, the other end of the resistor R4 is connected to the output end of the operational amplifier U1A, one end of the resistor R3 is connected to the negative input end of the operational amplifier U1A, the other end of the resistor R is connected to the COM end, one end of the capacitor C1 is connected to the output end of the operational amplifier U1A, and the other end of the capacitor C1 is connected to the second input end D2 of the range selection switch K1.
5. An input circuit of an ac clamp meter according to claim 4, wherein: the second operational amplifier circuit (3) is composed of an operational amplifier U1B, a resistor R5, a resistor R6 and a capacitor C2, wherein one end of the resistor R6 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R6 is connected to the output terminal of the operational amplifier U1B, one end of the resistor R5 is connected to the negative input terminal of the operational amplifier U1B, the other end of the resistor R5 is connected to the COM terminal, one end of the capacitor C2 is connected to the output terminal of the operational amplifier U1B, and the other end of the capacitor C2 is connected to the third input terminal D3 of the span selection switch K1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920982127.6U CN210572422U (en) | 2019-06-27 | 2019-06-27 | Input circuit of AC pincerlike meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920982127.6U CN210572422U (en) | 2019-06-27 | 2019-06-27 | Input circuit of AC pincerlike meter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210572422U true CN210572422U (en) | 2020-05-19 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920982127.6U Active CN210572422U (en) | 2019-06-27 | 2019-06-27 | Input circuit of AC pincerlike meter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN210572422U (en) |
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2019
- 2019-06-27 CN CN201920982127.6U patent/CN210572422U/en active Active
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: ZHANGZHOU EASTERN INTELLIGENT METER Co.,Ltd. Assignor: ZHANGZHOU YUSHAN ELECTRONIC MANUFACTURING CO.,LTD. Contract record no.: X2023980050007 Denomination of utility model: An input circuit for an AC clamp meter Granted publication date: 20200519 License type: Common License Record date: 20240110 |