CN213581144U - High-sensitivity ground wire impedance detection circuit - Google Patents
High-sensitivity ground wire impedance detection circuit Download PDFInfo
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- CN213581144U CN213581144U CN202022185841.8U CN202022185841U CN213581144U CN 213581144 U CN213581144 U CN 213581144U CN 202022185841 U CN202022185841 U CN 202022185841U CN 213581144 U CN213581144 U CN 213581144U
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Abstract
The utility model discloses a high sensitivity ground wire impedance detection circuitry, include: the first voltage transformer and the second voltage transformer are in a balanced state in an initial state, when the ground wire impedance changes, the balance is broken, the voltage difference is measured through the emitter follower and the inverting amplifier, and then the ground wire impedance is calculated through integration.
Description
Technical Field
The utility model relates to a ground wire impedance detection area, in particular to high sensitivity ground wire impedance detection circuitry.
Background
At present, for the resistance value detection of the ground wire resistor, a ground signal detection circuit for collecting phase line to ground signals is mostly used, the phase line to ground signals (sine wave signals) are collected through the ground signal detection circuit, the sine wave signals are amplified by an amplifying circuit and enter a shaping circuit for shaping to obtain pulse signals, the pulse signals are rectified by a rectifying circuit to obtain direct current voltage, a direct current voltage value of the rectifying circuit is read by an MCU, if the direct current voltage value falls into a preset standard value range in the MCU, the MCU outputs pulse signals with certain frequency, and therefore the resistance value of the ground wire resistor can be judged to be in a specified range; if the direct current voltage value of the rectifying circuit read by the MCU is not within the range of the preset standard value in the MCU, the MCU has no output, so that the resistance value of the ground wire resistor can be judged to be not within the specified range.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a high sensitivity ground wire impedance detection circuitry aims at solving the problem that above-mentioned background art mentioned.
In order to achieve the above object, the utility model provides a high sensitivity ground wire impedance detection circuit, include: a pin 1 of a primary coil of the first voltage transformer is grounded, a pin 2 is connected with a live wire, and a first sampling resistor is connected in series between a pin 3 and a pin 4 of a secondary coil of the first voltage transformer;
a pin 1 of a primary coil of the second voltage transformer is connected with a live wire, a pin 2 is connected with a zero line, a first sliding resistor is connected in series between a pin 3 and a pin 4 of a two-wire coil of the second voltage transformer, the pin 3 of the first voltage transformer is connected with the pin 3 of the second voltage transformer, and the current direction of the primary coil of the second voltage transformer is opposite to that of the primary coil of the first voltage transformer;
the pin 3 of the emitter follower is connected with an external voltage, and the pin 1 of the emitter follower is connected with the pin 4 of the second voltage transformer;
and a forward input pin of the inverting amplifier is connected with a pin 2 of the emitter follower, a pin 6 of the inverting amplifier is connected with a pin 4 of the first voltage transformer, and an output pin 7 of the inverting amplifier is connected with a voltage measuring instrument.
Optionally, the high-sensitivity ground impedance detection circuit further includes a first voltage-dividing resistor and a second voltage-dividing resistor, the first voltage-dividing resistor and the second voltage-dividing resistor are connected in series to a 3.3V external power supply, and the pin 3 of the emitter follower is connected between the first voltage-dividing resistor and the second voltage-dividing resistor.
Optionally, the high-sensitivity ground impedance detection circuit further includes a single chip, and the output pin 7 of the inverting amplifier is connected with an AD pin of the single chip to collect voltage.
Optionally, a first power resistor is connected in series between the pin 2 of the primary coil of the first voltage transformer and the live wire, and a second power resistor is connected in series between the pin 2 of the primary coil of the second voltage transformer and the live wire.
Optionally, the turn ratio of the primary coil and the secondary coil of each of the first voltage transformer and the second voltage transformer is 1: 1.
the utility model discloses technical scheme carries out the high low pressure through adopting to set up first voltage transformer and second voltage transformer and keeps apart to the symmetry gets into, produces opposite direction in the other one end of mutual-inductor, and two electric currents I1 and I2 that the phase difference is 180, when the geoline impedance is within the requirement scope, proofreaies and correct through sliding resistance, makes electric current I1 and I2 size equal, reaches the balance, and voltage acquisition is 1.65V DC offset voltage. When the ground wire impedance changes, the balance is broken, a voltage difference is generated, and the voltage difference is amplified and collected, so that the ground wire impedance is calculated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be 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 the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic diagram of the high-sensitivity ground impedance detection circuit of the present invention;
fig. 2 is a schematic structural diagram of an embodiment of the high-sensitivity ground impedance detection circuit of the present invention.
The reference numbers illustrate:
| reference numerals | Name (R) | Reference numerals | Name (R) |
| PT1 | First voltage transformer | PT2 | Second voltage transformer |
| U1 | Emitter follower | U2 | Inverting amplifier |
| R1 | A first sampling resistor | R2 | Second sampling resistor |
| R3 | Third sampling resistor | R4 | Sliding resistor |
| R5 | First voltage dividing resistor | R6 | Second voltage dividing resistor |
| R7 | A first resistor | R8 | Second resistance |
| R9 | A first power resistor | R10 | Second power resistor |
The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in 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 efforts belong to the protection scope of the present invention.
It should be noted that, if directional indications (such as upper, lower, left, right, front and rear … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description relating to "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
The utility model provides a high sensitivity ground wire impedance detection circuitry.
In the embodiment of the utility model, as in fig. 1, this detection circuitry uses first voltage transformer PT1 and second voltage transformer PT2 to keep apart, gets into through the symmetry, produces opposite direction in the other one end of mutual-inductor, and the phase difference is 180 electric current I1 and I2, when the ground wire impedance is within the required scope, corrects through sliding resistance, makes electric current I1 and I2 size equal, reaches the balance, and voltage acquisition is 1.65V direct current offset voltage. When the ground wire impedance changes, the balance is broken, a voltage difference is generated, the voltage difference is amplified and collected, and the ground wire impedance is calculated.
Specifically, as shown in fig. 2, in the present embodiment, the first potential transformer PT1 and the second potential transformer PT2 are of the type ZMPT107-1, the rated input current is 2mA, the rated output current is 2mA, the transformation ratio is 1000:1000, and the linearity is less than or equal to 0.2% (20% point-120% point);
a pin 2 of a primary coil of a first voltage transformer PT1 is connected with a live wire, and a pin 1 is grounded, so that a first voltage transformer PT1 measures the current of the live wire to the ground, and a pin 1 and a pin 2 of a primary coil of a second voltage transformer PT2 are respectively connected with the live wire and a zero wire, so that a second voltage transformer PT2 measures the current of the live wire to the zero wire, wherein pins connected with the live wire of the first voltage transformer PT1 and the second voltage transformer PT2 are both connected in series with power resistors, namely the pin 2 of the first voltage transformer PT1 is connected with the live wire after being connected with the first power resistor in series, the pin 2 of the second voltage transformer PT2 is connected with the live wire after being connected with the second power resistor in series, and the first power resistor and the second power resistor can play a role in voltage division and current reduction, thereby ensuring the safety;
a first sampling resistor R1 is connected in series between a pin 4 and a pin 3 of a secondary coil of the first voltage transformer PT1, a second sampling resistor R2, a third sampling resistor R3 and a sliding resistor R4 are arranged between a pin 4 and a pin 3 child of a secondary coil of the second voltage transformer PT2, wherein the third sampling resistor R3 is connected with the sliding resistor R4 in parallel and then is connected with the second sampling resistor R2 in series;
an emitter follower U1 is in a model of TP5532, a pin 3 of the emitter follower U1 is externally connected with a 3.3V power supply voltage, the 3.3V voltage passes through a first divider resistor R5 and a second divider resistor R6, the resistance values of the two divider resistors are the same, and the pin 3 is connected between the two divider resistors, so that the pin 3 inputs 1.65V voltage and outputs 1.65V bias voltage from a pin 2, the pin 3 is grounded through a first capacitor, the two pins 4 are connected with the 3.3V voltage, the pin 5 is grounded, and the pin 1 and the pin 2 are connected with a pin 4 of a second voltage transformer PT 2;
further, the type of the inverting amplifier U2 is TP5532, wherein a forward input pin 5 of the inverting amplifier U2 is connected to a pin 2 of the emitter follower U1, so that a bias voltage of 1.65V is input to the pin 2 of the inverting amplifier U2, a pin 6 of the inverting amplifier U2 is connected to a pin 4 of the first voltage transformer PT1, and an output terminal pin 7 of the inverting amplifier U2 is connected to a voltage detector, in this embodiment, a single chip microcomputer is provided, the pin 7 of the inverting amplifier U2 is connected to a monolithic AD pin, so that a voltage difference between the pin 4 of the first voltage transformer PT1 and the pin 4 of the second voltage transformer PT2 can be measured by the single chip microcomputer;
due to the error of the device precision, when the grounding is good, initially, the first voltage transformer PT1 and the second voltage transformer PT2 have the phenomenon of voltage unbalance, the error is eliminated through the sliding resistor R4, when the voltage reaches the balance, the amplitudes of sinusoidal signals with equal amplitude and opposite phases between the first voltage transformer PT1 and the second voltage transformer PT2 are equal, the sum of the two signals is 0, so that the pin 7 of the inverting amplifier U2 outputs 1.65V voltage, and when the voltage is used, the voltage reaches the balance state when the test voltage is 1.65V direct-current voltage through adjusting the sliding resistor R4;
further, when the ground impedance appears undulantly, then appear unbalanced voltage difference, gather the integral by singlechip AD after the amplifier U2 of reversal and calculate effective value, specific:
a first resistor R7 with the resistance value of 10K ohms is connected in series between the reverse input pin 6 and the pin 4 of the first voltage transformer PT1 of the reverse amplifier U2, a second resistor R8 with the resistance value of 200K ohms is arranged between the reverse input pin 6 and the output pin 7, therefore, the amplification factor of the reverse amplifier U2 is-20, U is the live wire voltage, the R power resistor singlechip acquires the voltage of Uo, the ground wire impedance is Rground, the turn ratio of the first voltage transformer PT1 to the second voltage transformer PT2 is 1:1, and the voltage difference equation U/R10-U/(R + Rground) 10 is Uo/20/2,
therefore, R is 400UR/(400U-UoR) -R
Therefore, the impedance to ground R ground can be obtained through calculation, the output pin 7 of the inverting amplifier U2 is connected with the AD pin of the single chip microcomputer, and the impedance of the ground wire can be monitored in real time.
The utility model discloses technical scheme is through adopting to set up first voltage transformer PT1 and second voltage transformer PT2 and at first keep apart high-low pressure, safe and reliable, secondly get into through two voltage transformer symmetries, produce opposite direction in the other one end of mutual-inductor, the phase difference is 180 electric current I1 and I2, when the ground wire impedance is within the requirement range, rectify through sliding resistance, make electric current I1 and I2 size equal, reach the balance, voltage acquisition is 1.65V DC offset voltage, when the ground wire impedance changes, break this balance, produce the voltage difference, then amplify the collection through reverse amplifier U2 to this voltage difference, calculate the ground wire impedance, thereby can carry out real-time supervision to the ground wire impedance.
The above only is the preferred embodiment of the present invention, not limiting the scope of the present invention, all the equivalent structure changes made by the contents of the specification and the drawings under the inventive concept of the present invention, or the direct/indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (5)
1. A high-sensitivity ground impedance detection circuit, comprising:
a pin 1 of a primary coil of the first voltage transformer is grounded, a pin 2 is connected with a live wire, and a first sampling resistor is connected in series between a pin 3 and a pin 4 of a secondary coil of the first voltage transformer;
a pin 1 of a primary coil of the second voltage transformer is connected with a live wire, a pin 2 is connected with a zero line, a first sliding resistor is connected in series between a pin 3 and a pin 4 of a two-wire coil of the second voltage transformer, the pin 3 of the first voltage transformer is connected with the pin 3 of the second voltage transformer, and the current direction of the primary coil of the second voltage transformer is opposite to that of the primary coil of the first voltage transformer;
the pin 3 of the emitter follower is connected with an external voltage, and the pin 1 of the emitter follower is connected with the pin 4 of the second voltage transformer;
and a forward input pin of the inverting amplifier is connected with a pin 2 of the emitter follower, a pin 6 of the inverting amplifier is connected with a pin 4 of the first voltage transformer, and an output pin 7 of the inverting amplifier is connected with a voltage measuring instrument.
2. The high-sensitivity ground impedance detection circuit according to claim 1, wherein the high-sensitivity ground impedance detection circuit further comprises a first voltage dividing resistor and a second voltage dividing resistor, the first voltage dividing resistor and the second voltage dividing resistor are connected in series to a 3.3V external power supply, and a pin 3 of the emitter follower is connected between the first voltage dividing resistor and the second voltage dividing resistor.
3. The high-sensitivity ground impedance detection circuit according to claim 2, wherein the high-sensitivity ground impedance detection circuit further comprises a single chip, and the output pin 7 of the inverting amplifier is connected with an AD pin of the single chip to collect voltage.
4. The high-sensitivity ground impedance detection circuit according to claim 3, wherein a first power resistor is connected in series between the pin 2 of the primary winding of the first voltage transformer and the live wire, and a second power resistor is connected in series between the pin 2 of the primary winding of the second voltage transformer and the live wire.
5. The high-sensitivity ground impedance detection circuit according to claim 4, wherein the turn ratio of the primary coil and the secondary coil of each of the first voltage transformer and the second voltage transformer is 1: 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022185841.8U CN213581144U (en) | 2020-09-29 | 2020-09-29 | High-sensitivity ground wire impedance detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022185841.8U CN213581144U (en) | 2020-09-29 | 2020-09-29 | High-sensitivity ground wire impedance detection circuit |
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| Publication Number | Publication Date |
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| CN213581144U true CN213581144U (en) | 2021-06-29 |
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| CN202022185841.8U Active CN213581144U (en) | 2020-09-29 | 2020-09-29 | High-sensitivity ground wire impedance detection circuit |
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