Three-phase voltage measuring device

Abstract

The utility model relates to a three-phase voltage measuring device which comprises an upper shell and a lower shell, a circuit board is arranged in the upper shell, a first voltage sensor, a second voltage sensor and a third voltage sensor are arranged on the circuit board, and a potentiometer is arranged at the top of the circuit board. One side of the circuit board is provided with an analog quantity signal output terminal and a power supply input terminal, and the other side of the circuit board is provided with two three-phase voltage signal input terminals; a power supply circuit, a signal conditioning circuit and an analog quantity output circuit are further arranged on the circuit board, a power supply is connected to the power supply circuit through the power supply input terminal, the power supply circuit is connected with the signal conditioning circuit, and the signal conditioning circuit is connected with the analog quantity output circuit; and the first voltage sensor, the second voltage sensor and the third voltage sensor are respectively connected to the signal conditioning circuit. According to the utility model, three voltage sensors are built in, so that the function of measuring three-phase voltage by a single device can be realized; a pure hardware analog circuit is adopted, no program exists inside, and the response speed is high.

Description

Technical Field

[0001] The utility model relates to the technical field of voltage measurement, in particular to a three-phase voltage measuring device. Background Art

[0002] With the continuous development of power grid technology, voltage measurement is becoming increasingly common in power systems to ensure the normal operation of power grid equipment. The accuracy, reliability, convenience, and speed of voltage measurement are crucial to the normal execution of processes such as energy metering, relay protection, and power system monitoring and diagnosis. Currently, most three-phase voltage measurement devices have the following drawbacks:

[0003] 1. Most three-phase voltage measuring devices are large in size and high in cost.

[0004] 2. Most small-volume voltage measuring devices can only measure single-phase voltage and cannot simultaneously measure the three-phase voltage in the power grid.

[0005] 3. Most three-phase voltage measurement devices use a single-chip microcomputer solution, which contains internal programs, has slow processing speed, and is high in cost. Summary of the Invention

[0006] The purpose of this utility model is to overcome the above-mentioned shortcomings and provide a three-phase voltage measuring device to solve the above-mentioned problems.

[0007] The purpose of this utility model is achieved in this way:

[0008] A three-phase voltage measuring device includes an outer shell composed of an upper shell and a lower shell with upper and lower buckles. The upper shell is provided with a circuit board, and the circuit board is provided with a first voltage sensor, a second voltage sensor, and a third voltage sensor. A potentiometer is provided on the top of the circuit board. One side of the circuit board is provided with an analog signal output terminal and a power input terminal, and the other side of the circuit board is provided with a three-phase voltage signal input terminal A and a three-phase voltage signal input terminal B.

[0009] The top surface of the upper shell is provided with an openable end cover, the position of the end cover corresponds to the position of the potentiometer below, and the potentiometer on the circuit board can be exposed by opening the end cover on the upper shell;

[0010] The circuit board is also provided with a power supply circuit, a signal conditioning circuit and an analog output circuit. The power supply is connected to the power supply circuit through the power input terminal. The power supply circuit steps down the input power supply and stabilizes it into the voltage required by the device; the power supply circuit is connected to the signal conditioning circuit, and the signal conditioning circuit is connected to the analog output circuit; the first voltage sensor, the second voltage sensor, and the third voltage sensor are respectively connected to the signal conditioning circuit to convert the collected three-phase voltage signal into an effective value signal, and the effective value signal is converted into a signal through the analog output circuit and finally transmitted to the outside through the analog signal output terminal; the three-phase voltage signal is isolated, transmitted and collected through the first voltage sensor, the second voltage sensor, and the third voltage sensor respectively. By adjusting the resistance of the potentiometer, the calibration of the device can be completed.

[0011] Furthermore, the power supply circuit includes a power chip U4 and a power module IC7. One side pin of the power chip U4 is connected to the power module IC7, and the other side pin is connected to the EMC protection circuit composed of the varistor RV1, TVS tube D8, inductor L4, and inductor L6, and the filter circuit composed of capacitor C32 and capacitor C33. The varistor RV1, TVS tube D8, capacitor C32 and capacitor C33 are connected in parallel and connected to the power chip U4. One end of the varistor RV1 and the TVS tube D8 are connected through the inductor L4, and the other end is connected through the inductor L6. A diode D7 and a fuse F1 are provided between the TVS tube D8 and the capacitor C32.

[0012] Furthermore, the signal processing circuit of the first voltage signal collected by the first voltage sensor 5 includes a voltage transformer T1, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC1B, a resistor R3 and a potentiometer U1, the signal rectification circuit is composed of an operational amplifier IC1A and a diode D1, the signal filtering circuit is composed of an operational amplifier IC2B, a resistor R9, a capacitor C9, a resistor R14, a capacitor C4, a resistor R6, a capacitor C3 and a resistor R2, the signal amplification circuit is composed of an operational amplifier IC2A, a resistor R17 and a resistor R16, and the output signal filtering circuit is composed of an inductor L1 and a capacitor C8.

[0013] Furthermore, the terminal 1 of the voltage transformer T1 is connected to the resistor R10, the resistor R11 and the resistor R12 in series. The resistors R10, R11 and R12 are current limiting resistors, which convert the first voltage signal into a small current signal. The voltage transformer T1 realizes the isolation and transmission of the small current signal; the terminal 3 and 4 of the voltage transformer T1 are connected to the resistor R8 and the diode D2 in parallel, the diode D2 is connected to the input end of the operational amplifier IC1B, and the output end of the operational amplifier IC1B is connected to the potentiometer U1 and the resistor R3. The potentiometer U1 and the resistor R3 are connected in series and then in parallel with the capacitor C1; the output end of the operational amplifier IC1B is connected to the resistors R1, R2 and R3 respectively after passing through the resistor R4. Diode D1 and operational amplifier IC1A; diode D1 is connected to resistor R9, resistor R9 is respectively connected to resistor R14 and capacitor C9, resistor R14 is respectively connected to capacitor C4 and resistor R6, capacitor C4 is connected to the negative input terminal of operational amplifier IC2B through resistor R2, resistor R6 and capacitor C3 are connected in parallel to the positive input terminal of operational amplifier IC2B, the output terminal of operational amplifier IC2B is respectively connected to capacitor C7 and the positive input terminal of operational amplifier IC2A, the negative input terminal of operational amplifier IC2A is respectively connected to resistor R17 and resistor R16, the input terminal of operational amplifier IC2A is connected to inductor L1, and inductor L1 is respectively connected to capacitor C8 and TVS tube TVS1.

[0014] Furthermore, the signal processing circuit of the second voltage signal collected by the second voltage sensor 6 includes a voltage transformer T2, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC3B, a resistor R20 and a potentiometer U2, the signal rectification circuit is composed of an operational amplifier IC3A and a diode D3, the signal filtering circuit is composed of an operational amplifier IC4B, a resistor R26, a capacitor C19, a resistor R31, a capacitor C14, a resistor R23, a capacitor C13 and a resistor R19, the signal amplification circuit is composed of an operational amplifier IC4A, a resistor R34 and a resistor R33, and the output signal filtering circuit is composed of an inductor L2 and a capacitor C18.

[0015] Furthermore, the terminal 1 of the voltage transformer T2 is connected to the resistor R27, the resistor R28 and the resistor R29 in series. The resistors R27, R28 and R29 are current limiting resistors, which convert the second voltage signal into a small current signal. The voltage transformer T2 realizes the isolation and transmission of the small current signal; the terminal 3 and 4 of the voltage transformer T2 are connected to the resistor R25 and the diode D4 in parallel, the diode D4 is connected to the input end of the operational amplifier IC3B, and the output end of the operational amplifier IC3B is connected to the potentiometer U2 and the resistor R20. The potentiometer U2 and the resistor R20 are connected in series and then connected in parallel with the capacitor C11; the output end of the operational amplifier IC3B is connected to the resistor R18, the diode D4 and the resistor R20 in series after passing through the resistor R21. D3 and operational amplifier IC3A; diode D3 is connected to resistor R26, resistor R26 is respectively connected to resistor R31 and capacitor C19, resistor R31 is respectively connected to capacitor C14 and resistor R23, capacitor C14 is connected to the negative input terminal of operational amplifier IC4B through resistor R19, resistor R23 and capacitor C13 are connected in parallel to the positive input terminal of operational amplifier IC4B, the output terminal of operational amplifier IC4B is respectively connected to capacitor C17 and the positive input terminal of operational amplifier IC4A, the negative input terminal of operational amplifier IC4A is respectively connected to resistor R34 and resistor R33, the input terminal of operational amplifier IC4A is connected to inductor L2, inductor L2 is respectively connected to capacitor C18 and TVS tube TVS2.

[0016] Furthermore, the signal processing circuit of the third voltage signal collected by the third voltage sensor 7 includes a voltage transformer T3, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC5B, a resistor R37 and a potentiometer U3, the signal rectification circuit is composed of an operational amplifier IC5A and a diode D5, the signal filtering circuit is composed of an operational amplifier IC6B, a resistor R43, a capacitor C29, a resistor R48, a capacitor C24, a resistor R40, a capacitor C23 and a resistor R36, the signal amplification circuit is composed of an operational amplifier IC6A, a resistor R51 and a resistor R50, and the output signal filtering circuit is composed of an inductor L3 and a capacitor C28.

[0017] Furthermore, the terminal 1 of the voltage transformer T3 is connected to the resistor R44, the resistor R45 and the resistor R46 in series. The resistors R44, R45 and R46 are current limiting resistors, which convert the third voltage signal into a small current signal. The voltage transformer T3 realizes the isolation and transmission of the small current signal; the terminal 3 and 4 of the voltage transformer T3 are connected to the resistor R42 and the diode D6 in parallel, the diode D6 is connected to the input end of the operational amplifier IC5B, and the output end of the operational amplifier IC5B is connected to the potentiometer U31 and the resistor R37. The potentiometer U3 and the resistor R37 are connected in series and then connected in parallel with the capacitor C21; the output end of the operational amplifier IC5B is connected to the resistor R35, the diode D6 and the resistor R37 in parallel after passing through the resistor R38. D5 and operational amplifier IC5A; diode D5 is connected to resistor R43, resistor R43 is respectively connected to resistor R48 and capacitor C29, resistor R48 is respectively connected to capacitor C24 and resistor R40, capacitor C24 is connected to the negative input terminal of operational amplifier IC6B through resistor R36, resistor R40 and capacitor C23 are connected in parallel to the positive input terminal of operational amplifier IC6B, the output terminal of operational amplifier IC6B is respectively connected to capacitor C27 and the positive input terminal of operational amplifier IC6A, the negative input terminal of operational amplifier IC6A is respectively connected to resistor R51 and resistor R50, the input terminal of operational amplifier IC6A is connected to inductor L3, inductor L3 is respectively connected to capacitor C28 and TVS tube TVS3.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The utility model provides a three-phase voltage measuring device with three built-in voltage sensors, which can realize the function of measuring three-phase voltage with a single device; the utility model adopts a pure hardware analog circuit, has no internal program, and has a fast response speed; the utility model has a simple structure and a small size, the shell thickness is 22.5mm, and it is installed on a guide rail, saving the user's installation space. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural diagram of the present utility model.

[0021] Figure 2 This is a principle block diagram of the utility model.

[0022] Figure 3 This is a circuit schematic diagram of the DC / DC conversion circuit of the present utility model.

[0023] Figure 4 This is a circuit schematic diagram of the first voltage signal processing circuit of the present utility model.

[0024] Figure 5 This is a circuit schematic diagram of the second voltage signal processing circuit of the present utility model.

[0025] Figure 6 This is a circuit schematic diagram of the third voltage signal processing circuit of the present utility model.

[0026] in:

[0027] Upper housing 1, circuit board 2, analog signal output terminal 3, power input terminal 4, first voltage sensor 5, second voltage sensor 6, third voltage sensor 7, lower housing 8, end cover 9, potentiometer 10, three-phase voltage signal input terminal A11, three-phase voltage signal input terminal B12, locking piece 13. DETAILED DESCRIPTION

[0028] To better understand the technical solution of the present invention, the following detailed description is provided with reference to the relevant illustrations. It should be understood that the following specific embodiments are not intended to limit the specific implementation of the technical solution of the present invention; they are merely examples of possible implementations of the technical solution of the present invention. It should be noted that the description herein of the positional relationships of the various components, such as component A being located above component B, is based on the relative positions of the components in the illustrations and is not intended to limit the actual positional relationships of the components. Example 1

[0029] See also Figures 1-6 , Figure 1 A schematic diagram of the structure of the present invention is provided. As shown in the figure, the present invention relates to a three-phase voltage measuring device, which includes an outer shell composed of an upper shell 1 and a lower shell 8 with upper and lower snaps. The upper shell 1 contains a circuit board 2, which is provided with a first voltage sensor 5, a second voltage sensor 6, and a third voltage sensor 7. A potentiometer 10 is provided on the top of the circuit board 2. One side of the circuit board 2 is provided with an analog signal output terminal 3 and a power input terminal 4. The other side of the circuit board 2 is provided with a three-phase voltage signal input terminal A11 and a three-phase voltage signal input terminal B12.

[0030] The top surface of the upper shell 1 is provided with an openable end cover 9 , the position of the end cover 9 corresponds to the position of the potentiometer 10 below. By opening the end cover 9 on the upper shell 1 , the potentiometer 10 on the circuit board 2 can be exposed.

[0031] A locking member 13 is provided at the bottom of the lower housing 8 .

[0032] join Figure 2 , Figure 2This is a block diagram of the principle of the present invention. As shown in the figure, the circuit board 2 is also equipped with a power supply circuit, a signal conditioning circuit, and an analog output circuit. The power supply is connected to the power supply circuit through the power input terminal 4. The power supply circuit steps down the input power supply and stabilizes it to the voltage required by the device. The power supply circuit is connected to the signal conditioning circuit, which is connected to the analog output circuit. The first voltage sensor 5, the second voltage sensor 6, and the third voltage sensor 7 are respectively connected to the signal conditioning circuit to convert the collected three-phase voltage signal into an effective value signal. The effective value signal is converted through the analog output circuit and finally transmitted to the outside through the analog signal output terminal 3. The three-phase voltage signal is isolated, transmitted, and collected by the first voltage sensor 5, the second voltage sensor 6, and the third voltage sensor 7. The device can be calibrated by adjusting the resistance of the potentiometer 10.

[0033] join Figure 3 , Figure 3 This is a schematic diagram of the DC / DC converter circuit of the present invention. As shown, the power supply circuit, namely the DC / DC converter circuit, comprises a power supply circuit with a DC 20-35V input, including a power supply chip U4 and a power module IC7. One pin of the power supply chip U4 is connected to the power module IC7, while the other pin is connected to an EMC protection circuit consisting of a varistor RV1, a TVS diode D8, an inductor L4, and an inductor L6, as well as a filter circuit consisting of capacitors C32 and C33. The varistor RV1, TVS diode D8, capacitors C32, and capacitors C33 are connected in parallel and then connected to the power supply chip U4. One end of the varistor RV1 and the TVS diode D8 are connected via inductor L4, and the other end is connected via inductor L6. A diode D7 and a fuse F1 are provided between the TVS diode D8 and capacitor C32. Diode D7 serves as an anti-reverse polarity device, fuse F1 provides current limiting protection, capacitors C32 and C33 serve as filters, power chip U4 realizes the conversion of output DC12V, and power module IC7 realizes the function of isolating the output DC12V.

[0034] join Figure 4 , Figure 4This is a circuit schematic diagram of the first voltage signal processing circuit of the present invention. As shown in the figure, the first voltage signal processing circuit, i.e., the signal processing circuit for the first voltage signal collected by the first voltage sensor 5, includes a voltage transformer T1, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit, and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC1B, a resistor R3, and a potentiometer U1; the signal rectification circuit is composed of an operational amplifier IC1A and a diode D1; the signal filtering circuit is composed of an operational amplifier IC2B, a resistor R9, a capacitor C9, a resistor R14, a capacitor C4, a resistor R6, a capacitor C3, and a resistor R2; the signal amplification circuit is composed of an operational amplifier IC2A, a resistor R17, and a resistor R16; and the output signal filtering circuit is composed of an inductor L1 and a capacitor C8.

[0035] Terminal 1 of the voltage transformer T1 is connected to resistors R10, R11, and R12 connected in series. Resistors R10, R11, and R12 are current-limiting resistors that convert the first voltage signal into a small current signal. The voltage transformer T1 implements isolated transmission of the small current signal. Terminals 3 and 4 of the voltage transformer T1 are connected to resistor R8 and diode D2 connected in parallel. Diode D2 is connected to the input of the operational amplifier IC1B. The output of the operational amplifier IC1B is connected to potentiometer U1 and resistor R3. Potentiometer U1 and resistor R3 are connected in series and then connected in parallel with capacitor C1. The output of the operational amplifier IC1B is connected to resistor R1, diode D1, and operational amplifier IC1A respectively after passing through resistor R4. ; Diode D1 is connected to resistor R9, resistor R9 is respectively connected to resistor R14 and capacitor C9, resistor R14 is respectively connected to capacitor C4 and resistor R6, capacitor C4 is connected to the negative input terminal of operational amplifier IC2B through resistor R2, resistor R6 and capacitor C3 are connected in parallel to the positive input terminal of operational amplifier IC2B, the output terminal of operational amplifier IC2B is respectively connected to capacitor C7 and the positive input terminal of operational amplifier IC2A, the negative input terminal of operational amplifier IC2A is respectively connected to resistor R17 and resistor R16, the input terminal of operational amplifier IC2A is connected to inductor L1, inductor L1 is respectively connected to capacitor C8 and TVS tube TVS1, TVS tube TVS1 plays the role of clamping the first output signal.

[0036] join Figure 5 , Figure 5This is a circuit schematic diagram of the second voltage signal processing circuit of the present invention. As shown in the figure, the second voltage signal processing circuit, i.e., the signal processing circuit for the second voltage signal collected by the second voltage sensor 6, includes a voltage transformer T2, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit, and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC3B, a resistor R20, and a potentiometer U2. The signal rectification circuit is composed of an operational amplifier IC3A and a diode D3. The signal filtering circuit is composed of an operational amplifier IC4B, a resistor R26, a capacitor C19, a resistor R31, a capacitor C14, a resistor R23, a capacitor C13, and a resistor R19. The signal amplification circuit is composed of an operational amplifier IC4A, a resistor R34, and a resistor R33. The output signal filtering circuit is composed of an inductor L2 and a capacitor C18.

[0037] The terminal 1 of the voltage transformer T2 is connected to the resistor R27, the resistor R28 and the resistor R29 in series. The resistors R27, R28 and R29 are current-limiting resistors, which convert the second voltage signal into a small current signal. The voltage transformer T2 realizes the isolation and transmission of the small current signal; the terminal 3 and 4 of the voltage transformer T2 are connected to the resistor R25 and the diode D4 in parallel. The diode D4 is connected to the input end of the operational amplifier IC3B. The output end of the operational amplifier IC3B is connected to the potentiometer U2 and the resistor R20. The potentiometer U2 and the resistor R20 are connected in series and then connected in parallel with the capacitor C11; the output end of the operational amplifier IC3B is connected to the resistor R18, the diode D3 and the operational amplifier IC3A respectively after passing through the resistor R21; Diode D3 is connected to resistor R26, resistor R26 is connected to resistor R31 and capacitor C19 respectively, resistor R31 is connected to capacitor C14 and resistor R23 respectively, capacitor C14 is connected to the negative input terminal of operational amplifier IC4B through resistor R19, resistor R23 and capacitor C13 are connected in parallel to the positive input terminal of operational amplifier IC4B, the output terminal of operational amplifier IC4B is connected to capacitor C17 and the positive input terminal of operational amplifier IC4A respectively, the negative input terminal of operational amplifier IC4A is connected to resistor R34 and resistor R33 respectively, the input terminal of operational amplifier IC4A is connected to inductor L2, inductor L2 is connected to capacitor C18 and TVS tube TVS2 respectively, TVS tube TVS2 plays the role of second output signal clamping

[0038] join Figure 6 , Figure 6This is a circuit schematic diagram of the third voltage signal processing circuit of the present invention. As shown in the figure, the third voltage signal processing circuit, i.e., the signal processing circuit for the third voltage signal collected by the third voltage sensor 7, includes a voltage transformer T3, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplification circuit, and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC5B, a resistor R37, and a potentiometer U3; the signal rectification circuit is composed of an operational amplifier IC5A and a diode D5; the signal filtering circuit is composed of an operational amplifier IC6B, a resistor R43, a capacitor C29, a resistor R48, a capacitor C24, a resistor R40, a capacitor C23, and a resistor R36; the signal amplification circuit is composed of an operational amplifier IC6A, a resistor R51, and a resistor R50; and the output signal filtering circuit is composed of an inductor L3 and a capacitor C28.

[0039] The connection terminal 1 of the voltage transformer T3 is connected to the resistor R44, the resistor R45 and the resistor R46 in series. The resistors R44, R45 and R46 are current limiting resistors, which convert the third voltage signal into a small current signal. The voltage transformer T3 realizes the isolation and transmission of the small current signal; the connection terminals 3 and 4 of the voltage transformer T3 are connected to the resistor R42 and the diode D6 in parallel. The diode D6 is connected to the input end of the operational amplifier IC5B. The output end of the operational amplifier IC5B is connected to the potentiometer U31 and the resistor R37. The potentiometer U3 and the resistor R37 are connected in series and then connected in parallel with the capacitor C21; the output end of the operational amplifier IC5B is connected to the resistor R35, the diode D5 and the operational amplifier IC5A respectively after passing through the resistor R38; Diode D5 is connected to resistor R43, which is respectively connected to resistor R48 and capacitor C29. Resistor R48 is respectively connected to capacitor C24 and resistor R40. Capacitor C24 is connected to the negative input terminal of operational amplifier IC6B via resistor R36. Resistor R40 and capacitor C23 are connected in parallel to the positive input terminal of operational amplifier IC6B. The output terminal of operational amplifier IC6B is respectively connected to capacitor C27 and the positive input terminal of operational amplifier IC6A. The negative input terminal of operational amplifier IC6A is respectively connected to resistor R51 and resistor R50. The input terminal of operational amplifier IC6A is connected to inductor L3. Inductor L3 is respectively connected to capacitor C28 and TVS diode TVS3. TVS diode TVS3 acts as a first output signal clamp.

[0040] Working principle:

[0041] Solder terminals 3, 4, 11, 12, the first voltage sensor 5, the second voltage sensor 6, and the third voltage sensor 7 to the circuit board 2, install the circuit board 2 into the lower shell 8, then connect the upper shell 1 and the lower shell 8 with a snap, install the circuit board 2 in the upper shell 1 and the lower shell 8, and finally install the locking piece 13 into the bottom of the lower shell 8. By opening the end cover 9 on the upper shell 1, the potentiometer 10 on the circuit board 2 can be exposed.

[0042] Terminal 4 is the power input terminal of the device. The power circuit on the circuit board 2 steps down the input power and stabilizes it into the voltage required by the device. Terminal 3 is the output terminal of the analog signal. The signal conditioning circuit on the circuit board 2 converts the signals collected by the first voltage sensor 5, the second voltage sensor 6 and the third voltage sensor 7 into effective value signals. The effective value signals are converted into signals through the analog output circuit and finally transmitted to the outside through terminal 3. Terminals 11 and 12 are the input terminals of the three-phase voltage signals. The three-phase voltage signals are isolated, transmitted and collected through the first voltage sensor 5, the second voltage sensor 6 and the third voltage sensor 7 respectively. The device can be calibrated by adjusting the resistance of the potentiometer 10.

[0043] The above are only specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. Any technical solution formed by equivalent transformation or equivalent replacement shall fall within the scope of protection of the present invention.

Claims

1. A three-phase voltage measuring device, characterized in that: It comprises an outer shell composed of an upper shell (1) and a lower shell (8) with upper and lower buckles, wherein a circuit board (2) is provided in the upper shell (1), a first voltage sensor (5), a second voltage sensor (6) and a third voltage sensor (7) are provided on the circuit board (2), a potentiometer (10) is provided on the top of the circuit board (2), an analog signal output terminal (3) and a power input terminal (4) are provided on one side of the circuit board (2), and a three-phase voltage signal input terminal A (11) and a three-phase voltage signal input terminal B (12) are provided on the other side of the circuit board (2); The top surface of the upper housing (1) is provided with an openable end cover (9), the position of the end cover (9) corresponds to the position of the potentiometer (10) below, and the potentiometer (10) on the circuit board (2) can be exposed by opening the end cover (9) on the upper housing (1); The circuit board (2) is also provided with a power supply circuit, a signal conditioning circuit and an analog output circuit. The power supply is connected to the power supply circuit through the power supply input terminal (4). The power supply circuit steps down the input power supply and stabilizes it into the voltage required by the device. The power supply circuit is connected to the signal conditioning circuit, and the signal conditioning circuit is connected to the analog output circuit. The first voltage sensor (5), the second voltage sensor (6) and the third voltage sensor (7) are respectively connected to the signal conditioning circuit to convert the collected three-phase voltage signal into an effective value signal. The effective value signal is converted into a signal through the analog output circuit and finally transmitted to the outside through the analog signal output terminal (3). The three-phase voltage signal is isolated, transmitted and collected through the first voltage sensor (5), the second voltage sensor (6) and the third voltage sensor (7). The device can be calibrated by adjusting the resistance of the potentiometer (10).

2. A three-phase voltage measuring device according to claim 1, characterized in that: The power supply circuit includes a power supply chip U4 and a power supply module IC7. One side pin of the power supply chip U4 is connected to the power supply module IC7, and the other side pin is connected to the EMC protection circuit composed of the varistor RV1, TVS tube D8, inductor L4, and inductor L6, and the filter circuit composed of capacitors C32 and C33. The varistor RV1, TVS tube D8, capacitor C32, and capacitor C33 are connected in parallel and connected to the power supply chip U4. One end of the varistor RV1 and the TVS tube D8 are connected through the inductor L4, and the other end is connected through the inductor L6. A diode D7 and a fuse F1 are provided between the TVS tube D8 and the capacitor C32.

3. A three-phase voltage measuring device according to claim 1, characterized in that: The signal processing circuit of the first voltage signal collected by the first voltage sensor (5) includes a voltage transformer T1, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplifying circuit and an output signal filtering circuit. The signal sampling circuit is composed of an operational amplifier IC1B, a resistor R3 and a potentiometer U1. The signal rectification circuit is composed of an operational amplifier IC1A and a diode D1. The signal filtering circuit is composed of an operational amplifier IC2B, a resistor R9, a capacitor C9, a resistor R14, a capacitor C4, a resistor R6, a capacitor C3 and a resistor R2. The signal amplifying circuit is composed of an operational amplifier IC2A, a resistor R17 and a resistor R16. The output signal filtering circuit is composed of an inductor L1 and a capacitor C8.

4. A three-phase voltage measuring device according to claim 3, characterized in that: The connection terminal 1 of the voltage transformer T1 is connected to the resistor R10, the resistor R11 and the resistor R12 in series. The resistors R10, R11 and R12 are current limiting resistors, which convert the first voltage signal into a small current signal. The voltage transformer T1 realizes the isolation and transmission of the small current signal; the connection terminals 3 and 4 of the voltage transformer T1 are connected to the resistor R8 and the diode D2 in parallel, the diode D2 is connected to the input end of the operational amplifier IC1B, and the output end of the operational amplifier IC1B is connected to the potentiometer U1 and the resistor R3. The potentiometer U1 and the resistor R3 are connected in series and then in parallel with the capacitor C1; the output end of the operational amplifier IC1B is connected to the resistor R1, the diode D2 and the input end of the operational amplifier IC1B respectively after passing through the resistor R4. D1 and operational amplifier IC1A; diode D1 is connected to resistor R9, resistor R9 is connected to resistor R14 and capacitor C9 respectively, resistor R14 is connected to capacitor C4 and resistor R6 respectively, capacitor C4 is connected to the negative input terminal of operational amplifier IC2B through resistor R2, resistor R6 and capacitor C3 are connected in parallel to the positive input terminal of operational amplifier IC2B, the output terminal of operational amplifier IC2B is connected to capacitor C7 and the positive input terminal of operational amplifier IC2A respectively, the negative input terminal of operational amplifier IC2A is connected to resistor R17 and resistor R16 respectively, the input terminal of operational amplifier IC2A is connected to inductor L1, inductor L1 is connected to capacitor C8 and TVS tube TVS1 respectively.

5. The three-phase voltage measuring device according to claim 1, characterized in that: The signal processing circuit of the second voltage signal collected by the second voltage sensor (6) comprises a voltage transformer T2, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplifying circuit and an output signal filtering circuit, wherein the signal sampling circuit is composed of an operational amplifier IC3B, a resistor R20 and a potentiometer U2, the signal rectification circuit is composed of an operational amplifier IC3A and a diode D3, the signal filtering circuit is composed of an operational amplifier IC4B, a resistor R26, a capacitor C19, a resistor R31, a capacitor C14, a resistor R23, a capacitor C13 and a resistor R19, the signal amplifying circuit is composed of an operational amplifier IC4A, a resistor R34 and a resistor R33, and the output signal filtering circuit is composed of an inductor L2 and a capacitor C18.

6. A three-phase voltage measuring device according to claim 5, characterized in that: The connection terminal 1 of the voltage transformer T2 is connected to the resistor R27, the resistor R28 and the resistor R29 in series. The resistors R27, R28 and R29 are current limiting resistors, which convert the second voltage signal into a small current signal. The voltage transformer T2 realizes the isolation and transmission of the small current signal; the connection terminals 3 and 4 of the voltage transformer T2 are connected to the resistor R25 and the diode D4 in parallel, the diode D4 is connected to the input end of the operational amplifier IC3B, and the output end of the operational amplifier IC3B is connected to the potentiometer U2 and the resistor R20. The potentiometer U2 and the resistor R20 are connected in series and then connected in parallel with the capacitor C11; the output end of the operational amplifier IC3B is connected to the resistor R18, the diode D3 and Operational amplifier IC3A; diode D3 is connected to resistor R26, resistor R26 is respectively connected to resistor R31 and capacitor C19, resistor R31 is respectively connected to capacitor C14 and resistor R23, capacitor C14 is connected to the negative input terminal of operational amplifier IC4B through resistor R19, resistor R23 and capacitor C13 are connected in parallel to the positive input terminal of operational amplifier IC4B, the output terminal of operational amplifier IC4B is respectively connected to capacitor C17 and the positive input terminal of operational amplifier IC4A, the negative input terminal of operational amplifier IC4A is respectively connected to resistor R34 and resistor R33, the input terminal of operational amplifier IC4A is connected to inductor L2, inductor L2 is respectively connected to capacitor C18 and TVS tube TVS2.

7. A three-phase voltage measuring device according to claim 1, characterized in that: The signal processing circuit of the third voltage signal collected by the third voltage sensor (7) comprises a voltage transformer T3, a signal sampling circuit, a signal rectification circuit, a signal filtering circuit, a signal amplifying circuit and an output signal filtering circuit, wherein the signal sampling circuit is composed of an operational amplifier IC5B, a resistor R37 and a potentiometer U3, the signal rectification circuit is composed of an operational amplifier IC5A and a diode D5, the signal filtering circuit is composed of an operational amplifier IC6B, a resistor R43, a capacitor C29, a resistor R48, a capacitor C24, a resistor R40, a capacitor C23 and a resistor R36, the signal amplifying circuit is composed of an operational amplifier IC6A, a resistor R51 and a resistor R50, and the output signal filtering circuit is composed of an inductor L3 and a capacitor C28.

8. A three-phase voltage measuring device according to claim 7, characterized in that: The connection terminal 1 of the voltage transformer T3 is connected to the resistor R44, the resistor R45 and the resistor R46 in series. The resistors R44, R45 and R46 are current limiting resistors, which convert the third voltage signal into a small current signal. The voltage transformer T3 realizes the isolation and transmission of the small current signal; the connection terminals 3 and 4 of the voltage transformer T3 are connected to the resistor R42 and the diode D6 in parallel, the diode D6 is connected to the input end of the operational amplifier IC5B, and the output end of the operational amplifier IC5B is connected to the potentiometer U31 and the resistor R37. The potentiometer U3 and the resistor R37 are connected in series and then connected in parallel with the capacitor C21; the output end of the operational amplifier IC5B is connected to the resistor R35 and the diode D5 after passing through the resistor R38. and operational amplifier IC5A; diode D5 is connected to resistor R43, resistor R43 is respectively connected to resistor R48 and capacitor C29, resistor R48 is respectively connected to capacitor C24 and resistor R40, capacitor C24 is connected to the negative input terminal of operational amplifier IC6B through resistor R36, resistor R40 and capacitor C23 are connected in parallel to the positive input terminal of operational amplifier IC6B, the output terminal of operational amplifier IC6B is respectively connected to capacitor C27 and the positive input terminal of operational amplifier IC6A, the negative input terminal of operational amplifier IC6A is respectively connected to resistor R51 and resistor R50, the input terminal of operational amplifier IC6A is connected to inductor L3, inductor L3 is respectively connected to capacitor C28 and TVS tube TVS3.

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