An electric leakage action protection tester

Abstract

The application discloses a leakage action protection tester, and belongs to the technical field of electric power, which comprises a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-gear current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a key group and a power module, and solves the technical problem that a high-precision multi-gear mA-level small current can be outputted, and the voltage at both ends of a leakage action device can be collected in stages. The application can output a high-precision mA-level alternating current, and has four gears, i.e., 4mA, 20mA and 100mA. According to the requirement, the application supports the staged real-time voltage collection detection and real-time voltage waveform display of the leakage action device, and records the voltage during the leakage action, so that the manual recording is reduced, and the application is more intelligent and efficient.

Description

Technical Field

[0001] This invention relates to the field of power technology, and in particular to a leakage current protection tester. Background Technology

[0002] There are many devices on the market for residual current protection (RCD). These devices all require RCD protection testing before leaving the factory. Previously, this was a simple test; however, with the continuous updating and upgrading of RCD devices, more rigorous and comprehensive testing is needed.

[0003] First, it's necessary to test and record the effective current value and waveform when the residual current device (RCD) trips. Second, it's necessary to display the applied current waveform and value in real time. Third, it's necessary to display the applied voltage waveform and value across the RCD in real time. Fourth, it's necessary to record the voltage waveform and tripping current value across the RCD when it trips to check if it meets the requirements of the leakage current rating and functionality. Therefore, a comprehensive RCD testing device is needed to perform this testing. However, current devices have the following limitations: 1. They require manual operation, resulting in low efficiency. 2. They cannot output high-precision, multi-level AC mA-level small currents. 3. They cannot collect the voltage across the RCD at different levels. 4. They cannot automatically record the tripping current and voltage waveforms. Summary of the Invention

[0004] The purpose of this invention is to provide a leakage current protection tester that solves the technical problem of being able to output high-precision, multi-level AC mA-level small current and to collect the voltage across the two ends of the leakage current protection device in stages.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A leakage current protection tester includes a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-level current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a keypad, and a power supply module. The display screen and the keypad are both connected to the main controller.

[0007] The input terminal of the voltage sampling circuit is connected to the voltage signal input interface, the output terminal is connected to the voltage signal processing unit, and the control terminal is connected to the output terminal of the relay signal isolation unit. The input terminal of the relay signal isolation unit is connected to the main controller. The output terminal of the voltage signal processing unit is connected to the input terminal of the voltage signal isolation unit, and the output terminal of the voltage signal isolation unit is connected to the main controller. The first reference voltage module provides a reference voltage for the voltage signal processing unit.

[0008] The voltage sampling circuit acquires the voltage signal from an external voltage source, isolates and performs AD conversion on the voltage signal through the voltage signal processing unit, and then sends it to the main controller. The relay signal isolation unit receives the relay control signal sent by the main controller and transmits the relay control signal to the voltage sampling circuit. The voltage sampling circuit controls its internal voltage divider relays and electronic switches according to the relay control signal. The voltage divider relays are used to select different voltage divider resistor networks in the voltage sampling circuit, and the electronic switches are used to adjust the gain of the amplifier in the voltage sampling circuit. The output terminal of the multi-level current output unit is connected to the current output interface, the control terminal is connected to the output terminal of the control signal isolation unit, and the input terminal is connected to the DA signal generator. The output and test terminals of the unit are connected to the input terminals of the fault detection unit, and the current signal sampling terminal is connected to the input terminal of the current AD conversion unit. The multi-level current output unit is used to output several different levels of current signals. The input terminal of the control signal isolation unit is connected to the main controller, and the output terminal of the current AD conversion unit is connected to the main controller. The second reference voltage module provides a reference voltage for the current AD conversion unit. The power supply module supplies power to the voltage sampling circuit, voltage signal processing unit, voltage signal isolation unit, first reference voltage module, relay signal isolation unit, current output interface, multi-level current output unit, control signal isolation unit, fault detection unit, current AD conversion unit, DA signal generation unit, and second reference voltage module.

[0009] Preferably, the power supply module includes a 15V power supply module, a 5V power supply module, a first 3.3V power supply module, and a second 3.3V power supply module. The input terminal of the 15V power supply module is connected to an external +13.5V power supply and a -13.5V power supply, and the output terminal outputs a +15V power supply and a -15V power supply. The input terminal of the 5V power supply module is connected to a +15V power supply and a -15V power supply, and the output terminal outputs a 5V power supply. The input terminal of the first 3.3V power supply module is connected to a 5V power supply, and the output terminal outputs a 3.3VCC power supply. The input terminal of the second 3.3V power supply module is connected to a 5V power supply, and the output terminal outputs a 3.3V power supply.

[0010] Preferably, the voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage divider channel selection circuit, an amplification isolation circuit, a differential amplification circuit, a controllable gain amplification circuit, and an electronic switch U10. The input terminal of the buffer U1 is connected to the X1 / 2I signal output from the output terminal of the relay signal isolation unit, and the output terminal outputs the X1 / 2 signal. The signal input interface J1 is used to connect to the voltage signal of an external voltage source. The input terminal of the voltage divider channel selection circuit is connected to the signal input interface J1, the control terminal is connected to the X1 / 2 signal, and the output terminal is connected to the input terminal of the amplification isolation circuit. The output terminal of the amplification isolation circuit is connected to the input terminal of the differential amplification circuit, and the output terminal of the differential amplification circuit is connected to the input terminal of the controllable gain amplification circuit. The output terminal of the controllable gain amplification circuit outputs the FBSIN signal and is connected to the input terminal of the voltage signal processing unit. The X5 signal output from the output terminal of the relay signal isolation unit is connected to the gain control terminal of the controllable gain amplification circuit. The gain control terminal of the controllable gain amplification circuit and the input terminal of the buffer U1 constitute the control terminal of the voltage sampling circuit.

[0011] Preferably, the voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13. The input terminal of the isolated voltage amplifier circuit constitutes the input terminal of the voltage signal processing unit, and its output terminal is connected to the input terminal of the AD module U13. The output terminal of the AD module U13 constitutes the output terminal of the voltage signal processing unit. The first reference voltage module provides reference voltages for the isolated voltage amplifier circuit and the AD module U13 respectively. The voltage signal isolation unit includes an isolator U9 and a resistor array R17. The input terminal of the isolator U9 constitutes the input terminal of the voltage signal isolation unit. The input terminal of the isolator U9 is connected to the output terminal of the AD module U13, and its output terminal is connected to a set of I / O ports of the main controller through the resistor array R17. The connection terminal of the resistor array R17 with the main controller constitutes the output terminal of the voltage signal isolation unit. The relay signal isolation unit includes an isolator U8 and a resistor array R16. The input terminal of the isolator U8 is connected to the main controller through the resistor array R16. The output terminal of the isolator U8 constitutes the output terminal of the relay signal isolation unit, and the connection terminal of the resistor array R16 with the main controller constitutes the input terminal of the relay signal isolation unit.

[0012] Preferably, the control signal isolation unit includes a drive register U23, a filter unit, a resistor array R67, an isolator U21, and a resistor array R51. The output of the drive register U23 constitutes the output of the control signal isolation unit. The input of the drive register U23 is connected to the output of the filter unit. The input of the filter unit is connected to the output of the isolator U21 through the resistor array R67. The input of the isolator U21 is connected to a set of I / O ports of the main controller through the resistor array R51. The output of the filter unit also outputs a / 1595 signal. The output of the drive register U23 outputs CTL1, CTL2, CTL3, and / EN signals respectively. The multi-level current output unit includes a relay group unit. The system includes a current sampling unit, transformer TI1, power amplifier unit, power amplifier enable unit, and DA signal amplitude control unit; the control terminals of the multi-level current output unit include control terminal A and control terminal B; the control terminals of the relay group unit constitute the control terminal A and output terminals of the multi-level current output unit; the relay group unit includes 3 relay groups, and the coil control terminals of these 3 relay groups constitute the control terminals of the relay group unit. The coil control terminals of the 3 relay groups are all controlled in parallel through parallel signals, which are composed of CTL1, CTL2, and CTL3 signals; in the 3 relay groups, the common contacts of each relay group are connected together to form 3 common contacts. The three common output terminals constitute the output terminals of the relay group unit. The normally open contact of each group of relays constitutes the relay input terminal of that group, forming a total of three relay input terminals. These three relay input terminals constitute the input terminals of the relay group unit. One relay input terminal is connected to pins 3, 4, and 5 of transformer TI1, and its corresponding common output terminal is connected to the current output interface. The other two relay input terminals are both connected to pin 6 of transformer TI1. Their corresponding two common output terminals are connected to the current output interface and output a US signal and connected to the input terminal of the current sampling unit. The output terminals of the current sampling unit output FBI and FB signals respectively. The output terminal that outputs the FBI signal constitutes a multi-stage range. The current signal sampling terminal of the current output unit, FB signal, is connected to the DA signal amplitude control unit; the DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit; the DA signal amplitude control unit is connected to the power amplifier enable unit, pins 1 and 2 of transformer TI1, and the power amplifier unit respectively; the test signal input terminal of the DA signal amplitude control unit constitutes the test terminal of the multi-level current output unit; the input terminal of the DA signal amplitude control unit constitutes the input terminal of the multi-level current output unit; the control terminal of the DA signal amplitude control unit constitutes the control terminal B of the multi-level current output unit, and the output terminal of the filter unit is also connected to the control terminal of the DA signal amplitude control unit; the output terminal of the power amplifier unit is connected to pin 2 of transformer TI1.

[0013] Preferably, the DA signal generation unit includes a resistor array R49, an isolator U18, a resistor array R61, a DA chip U26, and a DA signal isolation and amplification unit; the input terminal of the isolator U18 is connected to a set of I / O ports of the main controller through the resistor array R49, and the output terminal is connected to the input terminal of the DA chip U26 through the resistor array R61. The output terminal of the DA chip U26 is connected to the DA signal amplification and isolation unit, which constitutes the output terminal of the DA signal generation unit and outputs the SIN signal. The connection terminal of the resistor array R49 with the main controller constitutes the input terminal of the DA signal generation unit; the DA signal amplitude control unit includes... It includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit, and a power amplifier drive unit. The input terminal of the first isolation unit constitutes the input terminal of the DA signal amplitude control unit. The input terminal of the first isolation unit is connected to the output terminal of the DA signal amplification isolation unit, and the output terminal is connected to the input terminal of the DA chip U22. The control terminal of the DA chip U22 constitutes the control terminal of the DA signal amplitude control unit. The output terminal of the DA chip U22 is connected to the positive input terminal of the differential amplifier U28A through the second isolation unit. The FB signal is connected to the positive input terminal of the differential amplifier U28A.

[0014] The negative input terminal of the differential amplifier U28A is connected to the output terminal of the transformer signal amplification unit, and the input terminal of the transformer signal amplification unit is connected to pin 1 of the transformer TI1. The differential amplifier U28A is also connected to pin 2 of the transformer TI1 and the test signal input terminal of the DA signal amplitude control unit. The output terminal of the differential amplifier U28A is connected to the input terminal of the power amplifier drive signal unit, and the control terminal of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output terminal is connected to the power amplifier unit.

[0015] Preferably, the current AD conversion unit includes an amplification unit, an AD chip U31, a resistor array R80, an isolator U29, and a resistor array R100. The input terminal of the amplification unit constitutes the input terminal of the current AD conversion unit. The input terminal of the amplification unit is connected to the FBI signal, and the output terminal is connected to the AD chip U31. The output terminal of the AD chip U31 is connected to the input terminal of the isolator U29 through the resistor array R80. The output terminal of the isolator U29 is connected to the main controller through the resistor array R100. The connection terminal of the resistor array R100 and the main controller constitutes the output terminal of the current AD conversion unit.

[0016] The second reference voltage module includes a power supply chip U20, a first reference voltage generation unit, and a second reference voltage generation unit. The output terminal of the power supply chip U20 is connected to the first reference voltage generation unit and the second reference voltage generation unit respectively, and outputs a reference voltage Vre5V. The first reference voltage generation unit and the second reference voltage generation unit output reference voltages Vre2V and Vre10V respectively. The reference voltages Vre5V and Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

[0017] Preferably, the fault detection unit includes operational amplifier U17A, operational amplifier U17B, resistors R38, R45, R37, R44, R46, R53, capacitor C68, operational amplifier U24A, capacitor C82, diode D3, resistor R58, diode D4, resistor R60, resistor R70, diode D8, resistor R71, resistor R75, resistor R87, resistor R83, LED D17, and transistor Q2. Resistors R37 and R38 are connected in series, with one end connected to the TEST signal from the multi-level current output unit and the other end connected to ground. Pin 2 of operational amplifier U17A is connected to the junction of resistors R37 and R38, pin 3 is connected to a +15V power supply via resistor R45, and pin 1 is connected to the positive terminal of diode D3. Pin 6 of operational amplifier U17B is connected to a -15V power supply via resistor R46, and pin 5 is connected to the operational amplifier... Pins 2 and 7 of amplifier U17A are connected to pin 1 of operational amplifier U17A. Resistor R44 is connected between pin 3 of operational amplifier U17A and pin 6 of operational amplifier U17B. Resistor R53 is the pull-up resistor for pin 1 of operational amplifier U17A. Capacitor C68 is connected in parallel with resistor R53. The cathode of diode D3 is connected to pin 2 of operational amplifier U24A. Resistor R58 is connected in parallel with diode D3. Diode D3 is also connected to the anode of diode D4. Pin 3 of operational amplifier U24A is connected to pin 6 of operational amplifier U17B. Pin 1 of operational amplifier U24A is connected to the anode of diode D8. The cathode of diode D8 is connected to pin 5 of operational amplifier U24B. Pin 6 of operational amplifier U24B is connected to a +15V power supply through resistor R70. Pin 7 outputs a VOLD signal. The cathode of diode D4 is connected to pin 6 of operational amplifier U24B through resistor R60. Pin 6 of operational amplifier U24B is also connected to an / EN signal.

[0018] Pin 5 of operational amplifier U24B is connected to a -15V power supply through resistor R71, and resistor R75 is connected between pins 5 and 7 of operational amplifier U24B. Pin 7 of operational amplifier U24B is connected to the base of transistor Q2 through resistor R87. The emitter of transistor Q2 is connected to ground, and the collector is connected to a control signal FAIL output by isolator U18 through resistor array R61.

[0019] The positive terminal of LED D17 is connected to pin 7 of operational amplifier U24B via resistor R83, and the negative terminal is connected to ground.

[0020] The leakage current protection tester described in this invention solves the technical problem of being able to output high-precision, multi-level AC mA-level small currents and to collect the voltage across the two ends of leakage current-operated devices in a graded manner. This invention can output high-precision mA-level AC currents, with three levels: 4mA, 20mA, and 100mA, which can be selected according to requirements. It supports graded real-time voltage acquisition and detection and voltage display of leakage current-operated devices, as well as recording of current values ​​and voltage waveforms during leakage current operation, greatly reducing manual recording and making it more intelligent, convenient, and efficient. Attached Figure Description

[0021] Figure 1 This is a general principle block diagram of the present invention;

[0022] Figure 2 This is a block diagram of the voltage sampling circuit of the present invention.

[0023] Figure 3 This is a schematic block diagram of the voltage signal processing unit, voltage signal isolation unit, relay signal isolation unit, and first reference voltage module of the present invention.

[0024] Figure 4 This is a block diagram of the multi-level current output unit and control signal isolation unit of the present invention.

[0025] Figure 5 This is a block diagram of the schematic diagram of the DA signal generation unit and the DA signal amplitude control unit of the present invention;

[0026] Figure 6 This is a block diagram of the current-to-digital converter and the second reference voltage module of the present invention.

[0027] Figure 7 This is a block diagram of the power module schematic of the present invention;

[0028] Figure 8 This is a circuit diagram of the voltage signal processing unit, voltage signal isolation unit, relay signal isolation unit, and first reference voltage module of the present invention.

[0029] Figure 9This is a circuit diagram of the voltage sampling circuit of the present invention;

[0030] Figure 10 This is a circuit diagram of the control signal isolation unit of the present invention;

[0031] Figure 11 This is a circuit diagram of the relay group unit of the present invention;

[0032] Figure 12 This is a circuit diagram of the current sampling unit and transformer TI1 of the present invention;

[0033] Figure 13 This is a circuit diagram of the DA signal amplitude control unit of the present invention;

[0034] Figure 14 This is a circuit diagram of the power amplifier unit of the present invention;

[0035] Figure 15 This is a circuit diagram of the power amplifier enable unit of the present invention;

[0036] Figure 16 This is a circuit diagram of the fault detection unit of the present invention;

[0037] Figure 17 This is a circuit diagram of the DA signal generation unit of the present invention;

[0038] Figure 18 This is a circuit diagram of the current-to-digital converter unit of the present invention;

[0039] Figure 19 This is a circuit diagram of the second reference voltage module of the present invention;

[0040] Figure 20 This is a circuit diagram of the power supply module of the present invention. Detailed Implementation

[0041] like Figures 1-20 The leakage current protection tester shown includes a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-level current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a keypad, and a power supply module. The display screen and the keypad are both connected to the main controller.

[0042] The power supply module provides power to the voltage sampling circuit, voltage signal processing unit, voltage signal isolation unit, first reference voltage module, relay signal isolation unit, current output interface, multi-level current output unit, control signal isolation unit, fault detection unit, current AD conversion unit, DA signal generation unit, and second reference voltage module.

[0043] The power supply module includes a 15V power supply module, a 5V power supply module, a first 3.3V power supply module, and a second 3.3V power supply module. The input terminal of the 15V power supply module is connected to an external +13.5V power supply and a -13.5V power supply, and the output terminal outputs +15V power and -15V power. The input terminal of the 5V power supply module is connected to a +15V power supply and a -15V power supply, and the output terminal outputs 5V power. The input terminal of the first 3.3V power supply module is connected to a 5V power supply, and the output terminal outputs 3.3VCC power. The input terminal of the second 3.3V power supply module is connected to a 5V power supply, and the output terminal outputs M3.3V power.

[0044] In this embodiment, the 15V power supply module is chip U12. The input terminals +Vin and GND of chip U12 are connected to an externally provided +13.5V power supply and -13.5V power supply respectively through interface VCCIN1. The positive output terminal +VO and negative output terminal -VO of chip U12 output +15V power supply and -15V power supply respectively. Capacitors C43, C57 and C56 are filter capacitors on both sides of chip U12. The model of chip U12 is URA2415YMD-10WR3.

[0045] The first 5V power module is chip U16. Chip U16's input terminal VIN connects to a +15V power supply, and its output terminal VOUT outputs a 5V power supply. Capacitors C66, C73, and C76 are filter capacitors on both sides of chip U16. Chip U16's model number is ASM1117-5.0. The second 3.3V power module is chip U15. Chip U15's input terminal VIN connects to a 5V power supply, and its output terminal VOUT outputs a 3.3VCC power supply. Capacitors C67 and C75 are filter capacitors at the output terminal of chip U15. Chip U15's model number is ASM1117-5.0. The third 3.3V power module is chip U2. Chip U2's input terminal Vin connects to a 5V power supply, and its output terminal Vout outputs a 3.3V power supply. Capacitors C3, C4, C19, and C15 are filter capacitors on both sides of chip U2. Chip U2's model number is SP6205EM5-3.3.

[0046] The voltage sampling circuit has its input terminal connected to a voltage signal input interface, its output terminal connected to a voltage signal processing unit, and its control terminal connected to the output terminal of a relay signal isolation unit. The input terminal of the relay signal isolation unit is connected to the main controller. The voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage divider channel selection circuit, an amplification isolation circuit, a differential amplification circuit, a controllable gain amplification circuit, and an electronic switch U10. The input terminal of the buffer U1 is connected to the X1 / 2I signal output from the output terminal of the relay signal isolation unit, and its output terminal outputs the X1 / 2 signal. The signal input interface J1 is used to connect to the voltage signal from an external voltage source.

[0047] The input terminal of the voltage divider channel selection circuit is connected to the signal input interface J1, the control terminal is connected to the X1 / 2 signal, and the output terminal is connected to the input terminal of the amplification isolation circuit. The output terminal of the amplification isolation circuit is connected to the input terminal of the differential amplifier circuit, the output terminal of the differential amplifier circuit is connected to the input terminal of the controllable gain amplifier circuit, and the output terminal of the controllable gain amplifier circuit outputs the FBSIN signal, which is connected to the input terminal of the voltage signal processing unit. The X5 signal output from the output terminal of the relay signal isolation unit is connected to the gain control terminal of the controllable gain amplifier circuit. The gain control terminal of the controllable gain amplifier circuit and the input terminal of the buffer U1 constitute the control terminal of the voltage sampling circuit.

[0048] In this embodiment, the model of the buffer U1 is SN74LVC1G126-1, which is used to buffer the control signals sent from the main controller. Specifically, the generation channel of the X1 / 2 signal is as follows: after the relay signal isolation unit isolates the X1 / 2ID1 signal sent by the main controller, it generates the X1 / 2I signal, which is then buffered by the buffer U1 to finally generate the X1 / 2 signal.

[0049] The voltage divider channel selection circuit specifically includes a TVS diode V1, resistors R5 and R4, and a relay J33. Resistors R5 and R4 are sampling voltage divider resistors. After being connected in series, one end of resistors R5 and R4 is connected to pin 1 of the signal input interface J1, and the other end is connected to pin 2 of the input interface J1. TVS diode V1 is connected between pins 1 and 2 of the input interface J1 for TVS protection.

[0050] Relay J33 is divided into two parts in the circuit: J33A and J33B. J33A is the contact part, and J33B is the coil part. One end of J33B is connected to a 5V power supply, and the other end is controlled by the X1 / 2 signal. The common contact of J33A and the node of resistor R4 connected to pin 2 of input interface J1 form the output terminal of the voltage divider channel selection circuit, which is used to output the acquired voltage signal. The normally open terminal of J33A is connected to the node of resistor R5 and resistor R4, and the normally closed terminal is connected to the other end of resistor R5. By controlling relay J33, the voltage divider resistor can be selected in stages, thereby obtaining different levels of voltage acquisition values.

[0051] Both relay J33 and buffer U1 are powered by a 5V power supply. Power supply D5V in the diagram is the output voltage of the 5V power supply after isolation by a 10R resistor; its voltage value remains 5V. The amplification isolation circuit specifically includes resistors R8, R11, and R15, capacitor C21, diode U5, capacitor C33, and capacitor C34, amplifier U7, resistors R21, R24, R7, R10, and R14, capacitor C20, diode U4, capacitor C32, and capacitor C31, amplifier U6, resistors R20, and R23. The differential amplifier circuit consists of differential amplifier UC1 and its peripheral circuitry. Resistors R8, R11, R15, and C21, diode U5, capacitor C33, and capacitor C34, amplifier U7, resistors R21, and R24 constitute the first voltage acquisition channel of the amplification isolation circuit; one end of resistor R8 is connected to the common terminal of J33. Resistors R7, R10, R14, capacitor C20, diode U4, capacitor C32, capacitor C31, amplifier U6, resistor R20, and resistor R23 constitute the second voltage acquisition channel of the amplification isolation circuit; one end of resistor R7 is connected to the node where resistor R4 is connected to pin 2 of input interface J1.

[0052] The first and second voltage acquisition channels are connected to the positive input terminal IN+ and negative input terminal IN- of the differential amplifier UC1, respectively. Resistors R11, R15, and C21 form a filter network to filter the signal output from the common contact of J33A. Amplifier U7 forms a voltage follower for isolation. Resistors R21 and R24 form a voltage divider circuit to provide a voltage divider signal to the positive input terminal IN+ of the differential amplifier UC1. Diode U5, capacitors C33 and C34 provide a pull-up voltage to the positive input terminal of amplifier U7. In this embodiment, diode U5 is a BAV199(NP), with pins 1 and 2 connected to the +15V and -15V power supplies, respectively. Resistors R10 and R14, and capacitor C20 form a filter network to filter the signal output from one end of resistor R4. Amplifier U6 acts as a voltage follower, providing isolation. Resistors R20 and R23 form a voltage divider circuit to provide a voltage divider signal to the negative input terminal IN- of differential amplifier UC1. Diode U4, capacitors C32 and C31 provide a pull-up voltage to the positive input terminal of amplifier U6. In this embodiment, diode U4 is a BAV199(NP), with pins 1 and 2 connected to the +15V and -15V power supplies, respectively. Amplifiers U7 and U6 are both LTC2057HS8. Differential amplifiers UC1, U7, and U6 are all powered by +15V and -15V power supplies, respectively.

[0053] The model number of electronic switch U10 is TMUX6119. The input terminal of electronic switch U10, namely pin 8, is connected to the X5 signal. In the figure, electronic switch U10 is divided into two parts. The first part is the control part, namely U10A, and the second part is the toggle switch part, namely U10B. Electronic switch U10 is powered by a 5V power supply.

[0054] The controllable gain amplifier circuit consists of amplifier U14 and its peripheral circuits, as shown in the figure. Resistors R33 and R32 are connected in series, with one end connected to ground and the other end connected to the output terminal of amplifier U14. Capacitor C56 and resistor R29 are both peripheral circuits of amplifier U14.

[0055] Pin 7 of U10B connects to the output of amplifier U14, pin 5 connects to the junction of resistors R33 and R32, and pin 6 connects to the negative input of amplifier U14. Controlling U10A controls the operation of U10B, thus allowing selection of the resistance value of the feedback resistor from the output to the negative input of amplifier U14. Amplifier U14 is powered by both +15V and -15V power supplies. Amplifier U14 is model OP1177, and differential amplifier UC1 is model INA154.

[0056] The specific X5 signal generation channel is as follows: the relay signal isolation unit isolates the X5D1 signal sent by the main controller and then generates the X5 signal. In this embodiment, the main controller controls different values ​​of the X1 / 2ID1 signal and the X5D1 signal to achieve the acquisition and processing of voltage signals of different levels. The truth table is as follows:

[0057] X1 / 2ID1 X5D1 10V 0 0 5V 1 0 1V 1 1

[0058] Table 1

[0059] Ultimately, the output of the voltage sampling circuit is composed of the output of amplifier U14, and its output signal is the FBSIN signal. The FBSIN signal will be sent to the voltage signal processing unit for further processing later.

[0060] The output of the voltage signal processing unit is connected to the input of the voltage signal isolation unit, and the output of the voltage signal isolation unit is connected to the main controller. The first reference voltage module provides a reference voltage for the voltage signal processing unit. The voltage sampling circuit is used to acquire the voltage signal from the external voltage source, and after isolating and converting the voltage signal by the voltage signal processing unit, it is sent to the main controller. The relay signal isolation unit is used to receive the relay control signal sent by the main controller and transmit the relay control signal to the voltage sampling circuit. The voltage sampling circuit is used to control its internal voltage divider relays and electronic switches according to the relay control signal. The voltage divider relays are used to select different voltage divider resistor networks in the voltage sampling circuit, and the electronic switches are used to adjust the gain of the amplifier in the voltage sampling circuit.

[0061] The voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13. The input terminal of the isolated voltage amplifier circuit constitutes the input terminal of the voltage signal processing unit, and its output terminal is connected to the input terminal of the AD module U13. The output terminal of the AD module U13 constitutes the output terminal of the voltage signal processing unit. A first reference voltage module provides reference voltages for both the isolated voltage amplifier circuit and the AD module U13. The voltage signal isolation unit includes an isolator U9 and a resistor array R17. The input terminal of the isolator U9 constitutes the input terminal of the voltage signal isolation unit. The input terminal of the isolator U9 is connected to the output terminal of the AD module U13, and its output terminal is connected to a set of I / O ports of the main controller through the resistor array R17. The connection terminal of the resistor array R17 and the main controller constitutes the output terminal of the voltage signal isolation unit.

[0062] The relay signal isolation unit includes an isolator U8 and a resistor array R16. The input terminal of the isolator U8 is connected to the main controller through the resistor array R16. The output terminal of the isolator U8 constitutes the output terminal of the relay signal isolation unit. The connection terminal of the resistor array R16 and the main controller constitutes the input terminal of the relay signal isolation unit.

[0063] In this embodiment, the isolation voltage amplification circuit consists of a voltage follower composed of amplifier U3A and an amplification circuit composed of amplifier U3B. The FBSIN signal is first sent to the voltage follower, then to the negative input terminal of the amplification circuit, and then output to the positive input terminal IN+ of the AD module U13. The AD module U13 then performs AD conversion and sends the signal to the main controller for further identification. Resistors R9, R6, C14, and C18 are all peripheral circuits of amplifier U3A, while resistors R18, R19, C30, R22, R25, and diode D2 are all peripheral circuits of amplifier U3B. Amplifiers U3A and U3B are both OP2177, and the AD module U13 is AD7685CRM. The main controller performs statistical analysis on the identified voltage signal, generates a waveform graph, and displays it on the screen.

[0064] To protect the subsequent circuitry, this invention provides an isolation circuit, namely isolator U9 and its matching resistor array R17, when processing signals. The function of isolator U9 is to isolate the port of AD module U13 from the port of the main controller, thereby protecting the main controller.

[0065] The first reference voltage module consists of chip U11 and its peripheral circuitry. Chip U11 is model ADR435BRZ, and its output reference voltages include Vre5V1 and Vre2V1. Vre2V1 is connected to the positive input terminal of amplifier U3B, and Vre5V1 is connected to the REF terminal of AD module U13. Amplifiers U3A and U3B are powered by +15V and 15V power supplies, respectively. AD module U13 is powered by a 5V power supply. Isolators U9 and U8 are both powered by an M3.3V power supply. Isolators U9 and U8 are both model ADuM1401CRWZ. Isolator U8 is mainly used to isolate the X1 / 2ID1 and X5D1 signals sent by the main controller. These signals are ultimately converted into X1 / 2I and X5 signals. The X1 / 2I signal is ultimately used to control the operation of relay J33, and the X5 signal is ultimately used to control the operation of electronic switch U10.

[0066] The output terminal of the multi-level current output unit is connected to the current output interface, the control terminal is connected to the output terminal of the control signal isolation unit, the input terminal is connected to the output terminal of the DA signal generation unit, the test terminal is connected to the input terminal of the fault detection unit, and the current signal sampling terminal is connected to the input terminal of the current AD conversion unit. The multi-level current output unit is used to output current signals of several different levels. The input terminal of the control signal isolation unit is connected to the main controller, the output terminal of the current AD conversion unit is connected to the main controller, and the second reference voltage module provides a reference voltage for the current AD conversion unit.

[0067] The control signal isolation unit includes a driver register U23, a filter unit, a resistor array R67, an isolator U21, and a resistor array R51. The output of the driver register U23 forms the output of the control signal isolation unit. The input of the driver register U23 is connected to the output of the filter unit. The input of the filter unit is connected to the output of the isolator U21 through the resistor array R67. The input of the isolator U21 is connected to a set of I / O ports of the main controller through the resistor array R51. The output of the filter unit also outputs a / 1595 signal. The output of the driver register U23 outputs CTL1, CTL2, CTL3, and / EN signals, respectively. The isolator U21 receives control signals sent by the main controller, including the DINAIN data signal, the SCLKIN clock signal, the / CS1595IN chip select signal, and the / CS595IN chip select signal. Among these, the DINAIN data signal and the SCLKIN clock signal are common signals for the driver register U23 and the DA chip U22 in the subsequent circuit.

[0068] The / CS1595IN chip select signal enables the DA chip U22, and the / CS595IN chip select signal enables the driver register U23. Driver register U23 is a TPIC6B595, powered by a 5V power supply. Resistors R43 and C61, R56 and C72, R42 and C60, and R55 and C71 form four filter capacitors, which respectively filter the DINA signal, SCLK signal, and other signals isolated by isolator U21.

[0069] After filtering, the / CS1595 and / CS595 signals are sent to the input terminals of the driver register U23 and the DA chip U22. The isolator U21 is powered by a 3.3VCC power supply; the isolator U21 is model ADuM1400BRWZ. The driver register U23 outputs signals CTL1, CTL2, and CTL3, which are used to control the relay group unit in the subsequent circuit. The multi-level current output unit includes a relay group unit, a current sampling unit, a transformer TI1, a power amplifier unit, a power amplifier enable unit, and a DA signal amplitude control unit.

[0070] The control terminals of the multi-range current output unit include control terminal A and control terminal B; the control terminals of the relay group unit constitute control terminal A of the multi-range current output unit, and the output terminals constitute the output terminals of the multi-range current output unit; the relay group unit includes 3 relay groups, and the coil control terminals of these 3 relay groups constitute the control terminals of the relay group unit. The coil control terminals of the 3 relay groups are all controlled in parallel through parallel signals, which are composed of CTL1, CTL2, and CTL3 signals; in the 3 relay groups, the common contacts of each relay group are connected together to form 3 common output terminals, which constitute the output terminals of the relay group unit; the normally open contacts of each relay group constitute the relay input terminals of that group, forming 3 relay input terminals, which constitute the input terminals of the relay group unit; one relay input terminal is connected to pins 3, 4, and 5 of transformer TI1, and its corresponding common output terminal is connected to the current output interface;

[0071] The other two relay input terminals are connected to pin 6 of transformer TI1. Their corresponding two common output terminals are connected to the current output interface and the other outputs the US signal and connects to the input terminal of the current sampling unit.

[0072] In this embodiment, the relay group unit specifically includes relays J1, J2, J3, J4, J5, J6, and J7. In the figure, each of these relays is divided into two parts. For example, relay J1 includes J1B and J1A, relay J2 includes J2B and J2A, relay J3 includes J3B and J3A, relay J4 includes J4B and J4A, relay J5 includes J5B and J5A, relay J6 includes J6B and J6A, and relay J7 includes J7B and J7A. Taking relay J1 including J1B and J1A as an example, J1B is the coil part of relay J1, and J1A is the contact part of relay J1. Similarly, the representation of other relays is the same.

[0073] In this embodiment, relays J1, J2, J3, J4, J5, J6, and J7 are all powered by an external 12V power supply.

[0074] The coil control terminals of the three relay groups are all controlled in parallel via parallel signals, as follows: Relays J1, J2, and J3 form one group, with their coils J1B, J2B, and J3B driven by CTL1, CTL2, and CTL3 signals, respectively; Relays J4, J5, and J6 form another group, with their coils J4B, J5B, and J6B driven by CTL1, CTL2, and CTL3 signals, respectively; Relays J7, J8, and J9 form another group, with their coils J7B, J8B, and J9B driven by CTL1, CTL2, and CTL3 signals, respectively. The normally open contact of J1A is connected to pin 3 of transformer IT1, the normally open contact of J2A is connected to pin 4 of transformer IT1, and the normally open contact of J3A is connected to pin 5 of transformer IT1. The common contacts of J1A, J2A, and J3A are all connected together and connected to the pin of the current output interface. In this embodiment, the current output interface is interface IOUT1, and the common contacts of J1A, J2A, and J3A are all connected to pin 1 of interface IOUT1. The common contacts of J4A, J5A, and J6A are all connected together and connected to pin 2 of IOUT1. The normally open contacts of J4A, J5A, and J6A are all connected together and connected to pin 6 of transformer TI1. In this embodiment, pin 6 of transformer TI1 is connected to ground. The common contacts of J7A, J8A, and J9A are all connected together and output a US signal, which is sent to the current sampling unit for further processing. The normally open contact of J7A is connected to the normally open contact of J4A, the normally open contact of J8A is connected to the normally open contact of J5A, and the normally open contact of J9A is connected to the normally open contact of J6A. In this embodiment, the current signal output is selected using three relays in each group, enabling output switching between 100mA, 20mA, and 4mA. The main controller controls each relay individually through the drive register U23 to achieve this switching. The control truth table is shown in Table 2 below.

[0075] CTL1 CTL2 CTL3 100mA 0 1 1 20mA 1 0 1 4mA 1 1 0

[0076] Table 2

[0077] The output terminals of the current sampling unit output FBI and FB signals respectively. The output terminal that outputs the FBI signal constitutes the current signal sampling terminal of the multi-level current output unit, and the FB signal is connected to the DA signal amplitude control unit.

[0078] In this embodiment, the current sampling unit includes a first-stage amplifier consisting of amplifier U32B and its peripheral circuits, and a second-stage amplifier consisting of U32A. The negative input terminal of U32B is connected to the ground wire through resistor R116, the positive input terminal is connected to the US signal through resistor R113, and the output terminal outputs the FBI signal. One end of resistor R121 is connected to the negative input terminal of amplifier U32B, and the other end is connected to the negative output terminal of amplifier U32B.

[0079] The FBI signal is connected to the positive input terminal of amplifier U32A. The negative input terminal of amplifier U32A is connected to its output terminal. The negative output terminal of amplifier U32A outputs the FB signal, which is sent as a current feedback signal to the DA signal amplitude control unit. The DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit. The DA signal amplitude control unit is connected to the power amplifier enable unit, pins 1 and 2 of transformer TI1, and the power amplifier unit. The test signal input terminal of the DA signal amplitude control unit constitutes the test terminal of the multi-level current output unit. The input terminal of the DA signal amplitude control unit constitutes the input terminal of the multi-level current output unit. The control terminal of the DA signal amplitude control unit constitutes the control terminal B of the multi-level current output unit. The output terminal of the filter unit is also connected to the control terminal of the DA signal amplitude control unit. The output terminal of the power amplifier unit is connected to pin 2 of transformer TI1.

[0080] The power amplifier enable unit is a constant current drive circuit consisting of resistor R98, diode D18, voltage regulator U33, transistor Q5, transistor Q6 and diode D19. Resistors R105, R99, R110, R114, R115, R125, R123, R118, capacitors C119, C124, C140 and C141 are all peripheral circuits in the constant current drive circuit.

[0081] The constant current drive circuit provides the B+ and B- signals to drive the power amplifier drive signal unit. The B+ signal is output from the K terminal of the voltage regulator U33, and the B- signal is output from the A terminal of U33.

[0082] The / EN signal is input to the constant current drive circuit through resistor R98 to control its activation. Specifically, the / EN signal is connected to the base of transistor Q5 through resistors R98 and R99, and the anode of diode D18 is connected to an OVLD signal output from the input of the fault detection unit. The voltage regulator U33 is a TL431. The output of the power amplifier drive signal unit outputs UP and DOWN signals to control the power amplifier unit.

[0083] The power amplifier unit is a power amplifier circuit composed of transistors Q7, Q8, Q9, Q10, MOSFET Q12, and MOSFET Q11. Transistors Q8, Q9, and Q12 are used to amplify rising edge signals, while transistors Q7, Q10, and Q11 are used to amplify falling edge signals. The UP signal is input to the base of transistor Q8, and the DOWM signal is input to the base of transistor Q7. The drains of MOSFETs Q12 and Q11 together form the output terminal of the power amplifier unit, which is used to output the MOS signal for controlling transformer TI1. The MOS signal is connected to pin 2 of transformer TI1.

[0084] The fault detection unit includes operational amplifier U17A, operational amplifier U17B, resistors R38, R45, R37, R44, R46, R53, capacitor C68, operational amplifier U24A, capacitor C82, diode D3, resistor R58, diode D4, resistor R60, resistor R70, diode D8, resistor R71, resistor R75, resistor R87, resistor R83, LED D17, and transistor Q2. Resistors R37 and R38 are connected in series, with one end connected to the TEST signal from the multi-level current output unit and the other end connected to ground. Pin 2 of operational amplifier U17A is connected to the junction of resistors R37 and R38, pin 3 is connected to the +15V power supply via resistor R45, and pin 1 is connected to the positive terminal of diode D3. Pin 6 of operational amplifier U17B is connected to the -15V power supply via resistor R46, and pin 5 is connected to the operational amplifier... Pins 2 and 7 of U17A are connected to pin 1 of operational amplifier U17A. Resistor R44 is connected between pin 3 of operational amplifier U17A and pin 6 of operational amplifier U17B. Resistor R53 is the pull-up resistor for pin 1 of operational amplifier U17A. Capacitor C68 is connected in parallel with resistor R53. The cathode of diode D3 is connected to pin 2 of operational amplifier U24A. Resistor R58 is connected in parallel with diode D3. Diode D3 is also connected to the anode of diode D4. Pin 3 of operational amplifier U24A is connected to pin 6 of operational amplifier U17B. Pin 1 of operational amplifier U24A is connected to the anode of diode D8. The cathode of diode D8 is connected to pin 5 of operational amplifier U24B. Pin 6 of operational amplifier U24B is connected to a +15V power supply through resistor R70. Pin 7 outputs a VOLD signal. The cathode of diode D4 is connected to pin 6 of operational amplifier U24B through resistor R60. Pin 6 of operational amplifier U24B is also connected to an / EN signal.

[0085] Pin 5 of operational amplifier U24B is connected to a -15V power supply through resistor R71, and resistor R75 is connected between pins 5 and 7 of operational amplifier U24B. Pin 7 of operational amplifier U24B is connected to the base of transistor Q2 through resistor R87. The emitter of transistor Q2 is connected to ground, and the collector is connected to a control signal FAIL output by isolator U18 through resistor array R61.

[0086] The positive terminal of LED D17 is connected to pin 7 of operational amplifier U24B via resistor R83, and the negative terminal is connected to ground. The FAIL signal is first isolated by isolator U18, generating the FAILOUT signal, and then sent to an I / O port of the main controller for further identification. The fault detection unit determines whether a fault has occurred by detecting the signal output by differential amplifier U28A.

[0087] Operational amplifiers U17A and U17B are both LM393, and operational amplifiers U24A and U24B are both LM358N. The DA signal generation unit includes a resistor array R49, an isolator U18, a resistor array R61, a DA chip U26, and a DA signal isolation amplification unit. The input of isolator U18 is connected to a set of I / O ports of the main controller via resistor array R49, and its output is connected to the input of DA chip U26 via resistor array R61. The output of DA chip U26 is connected to the DA signal amplification isolation unit, which constitutes the output of the DA signal generation unit and outputs the SIN signal. The connection point of resistor array R49 to the main controller constitutes the input of the DA signal generation unit.

[0088] In this embodiment, isolator U18 is used to isolate the control terminal of DA chip U26 from the main controller. Specifically, the SCK2, SDIN2, and SLD2 signals sent by the main controller are isolated by isolator U18 and converted into SCK, SDIN, and SLD signals, which are then input to pins 7, 6, and 5 of U26. DA chip U26 is an LTC1595, powered by a 5V power supply, and its reference voltage is the reference voltage Vre10V provided by the second reference voltage module. The DA signal isolation amplification unit is a two-stage amplification circuit consisting of amplifiers U27A and U27B. Amplifier U27A is the first stage amplification circuit, and amplifier U27B is the second stage amplification circuit. Capacitors C100, C99, and C97 are peripheral circuits of amplifier U27A, and resistors R79, R82, R92, and capacitor C109 are peripheral circuits of amplifier U27B. The positive input terminal of amplifier U27A is connected to ground, the negative input terminal is connected to the OUT terminal of DA chip U26, and the output terminal is connected to the negative input terminal of amplifier U27B through resistor R82. The positive input terminal of amplifier U27B is connected to ground, and the output terminal outputs the SIN signal. Amplifiers U27A and U27B are both model OP2177, and isolator U18 is model ADuM1401CRWZ.

[0089] The DA signal amplitude control unit includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit, and a power amplifier drive unit. The input terminal of the first isolation unit constitutes the input terminal of the DA signal amplitude control unit. The input terminal of the first isolation unit is connected to the output terminal of the DA signal amplification isolation unit, and the output terminal is connected to the input terminal of the DA chip U22. The control terminal of the DA chip U22 constitutes the control terminal of the DA signal amplitude control unit. The output terminal of the DA chip U22 is connected to the positive input terminal of the differential amplifier U28A through the second isolation unit. The FB signal is connected to the positive input terminal of the differential amplifier U28A.

[0090] The negative input terminal of differential amplifier U28A is connected to the output terminal of the transformer signal amplification unit, and the input terminal of the transformer signal amplification unit is connected to pin 1 of transformer TI1. Differential amplifier U28A is also connected to pin 2 of transformer TI1 and the test signal input terminal of the DA signal amplitude control unit. The output terminal of differential amplifier U28A is connected to the input terminal of the power amplifier drive signal unit. The control terminal of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output terminal is connected to the power amplifier unit. In this embodiment, the first isolation unit is an amplification isolation circuit composed of amplifier U19B. Resistors R41, R39, R50, capacitors C62 and C63 are all peripheral circuits of amplifier U19B. The positive input terminal of amplifier U19B is connected to the SIN signal through resistors R41 and R50 connected in series, and the output terminal is connected to the VREF terminal of DA chip U22. The OUT terminal of DA chip U22 is connected to the negative input terminal of amplifier U19A. DA chip U22 is powered by a 5V power supply, and the model of DA chip U22 is LTC1595BCS8. The second isolation unit is an amplification isolation circuit composed of amplifier U19A. The output of amplifier U19A is connected to the positive input of differential amplifier U28A through a resistor R74. Both amplifiers U19A and U19B are model OP2177. The FB signal is also connected to the positive input of differential amplifier U28A through a resistor RF1. Resistors R77, R78, R93, R86, R85, ER2, R94, and capacitors C108, C112, C110, and C117 are all peripheral circuits of differential amplifier U28A. The output of differential amplifier U28A also outputs a TEST signal for testing.

[0091] The transformer signal amplification unit is an amplifier circuit composed of amplifier U28B. The negative input terminal of amplifier U28B is connected to pin 1 of transformer TI1 through resistor R72. A 3.6V Zener diode is also connected to the negative input terminal of amplifier U28B. Resistor ER1 and capacitor C101 are external circuitry of amplifier U28B. The output terminal of amplifier U28B is connected to the negative input terminal of amplifier U28A through resistor R78. Both amplifiers U28B and U28A are model OP2177.

[0092] The power amplifier drive signal unit provides drive signals to the power amplifier unit. It includes transistors Q4 and Q3, resistors R104 and R103. The bases of transistors Q4 and Q3 form the control terminals of the power amplifier drive signal unit, both connected to the power amplifier enable unit to receive the enable signal, B+ signal, and B- signal sent by the enable unit. The emitter of transistor Q4 is connected to one end of resistor R94 through resistor R104. The other end of resistor R94 is connected to the output terminal of amplifier U28A. The emitter of transistor Q3 is connected to one end of resistor R94. The collectors of transistors Q4 and Q3 form the output terminals of the power amplifier drive signal unit, outputting the UP and DOWN signals used to control the power amplifier unit. The emitters of transistors Q3 and Q4 form the input terminals of the power amplifier drive signal unit.

[0093] The current-to-AD conversion unit includes an amplifier unit, an AD chip U31, a resistor array R80, an isolator U29, and a resistor array R100. The input terminal of the amplifier unit constitutes the input terminal of the current-to-AD conversion unit. The input terminal of the amplifier unit is connected to the FBI signal, and the output terminal is connected to the AD chip U31. The output terminal of the AD chip U31 is connected to the input terminal of the isolator U29 through the resistor array R80. The output terminal of the isolator U29 is connected to the main controller through the resistor array R100. The connection terminal of the resistor array R100 and the main controller constitutes the output terminal of the current-to-AD conversion unit.

[0094] In this embodiment, the amplification unit is a current amplification circuit composed of amplifiers U30A and U30B. Amplifier U30A constitutes a first-stage amplification circuit, and amplifier U30B constitutes a second-stage amplification circuit. Resistors R81 and R88, capacitors C107 and C113 constitute the peripheral circuit of amplifier U30A, and resistors R96, R101, C118, R106, and C127 constitute the peripheral circuit of amplifier U30B. The FBI signal enters the positive input terminal of amplifier U30A through resistors R81 and R88. After being amplified by the first stage of amplifier U30A, it is input to the negative input terminal of amplifier U30B. After being amplified by the second stage of amplifier U30B, it is output to the input terminal of AD chip U31, namely IN+ of AD chip U31.

[0095] The control terminal of AD chip U31 is connected to the main controller after being isolated by isolator U29. Specifically, pins 8, 7 and 6 of AD chip U31 are connected to the SCLK1 signal, SDOUT signal and CNVA signal respectively. The SCLK1 signal, SDOUT signal and CNVA signal are obtained by isolator U29 after isolating the SCLK2 signal, CNVA2 signal and SDOUT2 signal sent by the main controller.

[0096] The reference voltage of AD chip U31 is Vre5V.

[0097] The isolator U29 is model ADuM14101CRWZ, the AD chip U31 is model AD7685, and the amplifiers U30A and U30B are both model OP2177.

[0098] The second reference voltage module includes a power supply chip U20, a first reference voltage generation unit, and a second reference voltage generation unit. The output terminal of the power supply chip U20 is connected to the first reference voltage generation unit and the second reference voltage generation unit respectively, and outputs a reference voltage Vre5V. The first reference voltage generation unit and the second reference voltage generation unit output reference voltages Vre2V and Vre10V respectively. The reference voltages Vre5V and Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

[0099] In this embodiment, the power chip U20 is model MAX6250ACSA. The first reference voltage generation unit is composed of amplifier U25A and its peripheral circuits. The second reference voltage generation unit is composed of amplifier U25B and its peripheral circuits. The output terminal OUT of the power chip U20 is connected to the positive input terminal of amplifier U25B and outputs a reference voltage Vre5V.

[0100] The output of amplifier U25B is connected to the base of transistor Q1 through resistor R73. The emitter of transistor Q1 is connected to the negative input of amplifier U25B through resistor R68. The emitter of transistor Q1 outputs a reference voltage Vre10V.

[0101] The OUT terminal of the power chip U20 is divided by voltage divider resistors R64 and R63 and then input to the positive input terminal of amplifier U25A. The output terminal of U25A outputs a reference voltage Vre2V.

[0102] Both amplifiers U25B and U25A are OP2177.

[0103] The leakage current protection tester described in this invention solves the technical problem of being able to output high-precision, multi-level AC mA-level small currents and to collect the voltage across the two ends of leakage current-operated devices in a graded manner. This invention can output high-precision mA-level AC currents, with three levels: 4mA, 20mA, and 100mA, which can be selected according to requirements. It supports graded real-time voltage acquisition and detection and voltage display of leakage current-operated devices, as well as voltage recording during leakage current operation, greatly reducing manual recording and making it more intelligent, convenient, and efficient.

Claims

1. A leakage current protection tester, characterized in that: It includes a voltage sampling circuit, a voltage signal processing unit, a voltage signal isolation unit, a first reference voltage module, a relay signal isolation unit, a current output interface, a multi-level current output unit, a control signal isolation unit, a fault detection unit, a current AD conversion unit, a DA signal generation unit, a second reference voltage module, a main controller, a display screen, a keypad, and a power supply module. The display screen and keypad are both connected to the main controller. The input terminal of the voltage sampling circuit is connected to the voltage signal input interface, the output terminal is connected to the voltage signal processing unit, and the control terminal is connected to the output terminal of the relay signal isolation unit. The input terminal of the relay signal isolation unit is connected to the main controller. The output of the voltage signal processing unit is connected to the input of the voltage signal isolation unit, and the output of the voltage signal isolation unit is connected to the main controller. The first reference voltage module provides a reference voltage for the voltage signal processing unit. The voltage sampling circuit is used to acquire the voltage signal from the external voltage source, and after the voltage signal is isolated and converted by the voltage signal processing unit, it is sent to the main controller. The relay signal isolation unit is used to receive the relay control signal sent by the main controller and transmit the relay control signal to the voltage sampling circuit. The voltage sampling circuit is used to control the voltage divider relay and electronic switch inside itself according to the relay control signal. The voltage divider relay is used to select different voltage divider resistor networks in the voltage sampling circuit, and the electronic switch is used to adjust the gain of the amplifier in the voltage sampling circuit. The output terminal of the multi-level current output unit is connected to the current output interface, the control terminal is connected to the output terminal of the control signal isolation unit, the input terminal is connected to the output terminal of the DA signal generation unit, the test terminal is connected to the input terminal of the fault detection unit, and the current signal sampling terminal is connected to the input terminal of the current AD conversion unit. The multi-level current output unit is used to output current signals at several different levels; The input terminal of the control signal isolation unit is connected to the main controller, the output terminal of the current AD conversion unit is connected to the main controller, and the second reference voltage module provides a reference voltage for the current AD conversion unit. The power supply module provides power to the voltage sampling circuit, voltage signal processing unit, voltage signal isolation unit, first reference voltage module, relay signal isolation unit, current output interface, multi-level current output unit, control signal isolation unit, fault detection unit, current AD conversion unit, DA signal generation unit, and second reference voltage module.

2. The leakage current protection tester as described in claim 1, characterized in that: The power module includes a 15V power module, a 5V power module, a first 3.3V power module and a second 3.3V power module. The input terminal of the 15V power module is connected to an external +13.5V power supply and a -13.5V power supply, and the output terminal outputs a +15V power supply and a -15V power supply. The input terminals of the 5V power module are connected to a +15V power supply and a -15V power supply, and the output terminal outputs a 5V power supply. The first 3.3V power module has a 5V power supply at its input and a 3.3VCC power supply at its output. The second 3.3V power module has a 5V power supply at its input and an M3.3V power supply at its output.

3. The leakage current protection tester as described in claim 1, characterized in that: The voltage sampling circuit includes a buffer U1, a signal input interface J1, a voltage divider channel selection circuit, an amplification isolation circuit, a differential amplifier circuit, a controllable gain amplifier circuit, and an electronic switch U10. The input terminal of the buffer U1 is connected to the X1 / 2I signal output from the output terminal of the relay signal isolation unit, and the output terminal outputs the X1 / 2 signal. The signal input interface J1 is used to connect to the voltage signal of an external voltage source; The input terminal of the voltage divider channel selection circuit is connected to the signal input interface J1, the control terminal is connected to the X1 / 2 signal, and the output terminal is connected to the input terminal of the amplification isolation circuit. The output terminal of the amplification isolation circuit is connected to the input terminal of the differential amplifier circuit. The output terminal of the differential amplifier circuit is connected to the input terminal of the controllable gain amplifier circuit. The output terminal of the controllable gain amplifier circuit outputs the FBSIN signal and is connected to the input terminal of the voltage signal processing unit. The X5 signal output from the relay signal isolation unit is connected to the gain control terminal of the controllable gain amplifier circuit. The gain control terminal of the controllable gain amplifier circuit and the input terminal of the buffer U1 constitute the control terminal of the voltage sampling circuit.

4. The leakage current protection tester as described in claim 1, characterized in that: The voltage signal processing unit includes an isolated voltage amplifier circuit and an AD module U13. The input terminal of the isolated voltage amplifier circuit constitutes the input terminal of the voltage signal processing unit, and the output terminal is connected to the input terminal of the AD module U13. The output terminal of the AD module U13 constitutes the output terminal of the voltage signal processing unit. The first reference voltage module provides reference voltages for the isolation voltage amplifier circuit and the AD module U13, respectively. The voltage signal isolation unit includes an isolator U9 and a resistor array R17. The input terminal of the isolator U9 constitutes the input terminal of the voltage signal isolation unit. The input terminal of the isolator U9 is connected to the output terminal of the AD module U13, and the output terminal is connected to a set of I / O ports of the main controller through the resistor array R17. The connection terminal of the resistor array R17 and the main controller constitutes the output terminal of the voltage signal isolation unit. The relay signal isolation unit includes an isolator U8 and a resistor array R16. The input terminal of the isolator U8 is connected to the main controller through the resistor array R16. The output terminal of the isolator U8 constitutes the output terminal of the relay signal isolation unit. The connection terminal of the resistor array R16 and the main controller constitutes the input terminal of the relay signal isolation unit.

5. The leakage current protection tester as described in claim 1, characterized in that: The control signal isolation unit includes a drive register U23, a filter unit, a resistor array R67, an isolator U21, and a resistor array R51. The output of the drive register U23 constitutes the output of the control signal isolation unit. The input of the drive register U23 is connected to the output of the filter unit. The input of the filter unit is connected to the output of the isolator U21 through the resistor array R67. The input of the isolator U21 is connected to a set of I / O ports of the main controller through the resistor array R51. The output of the filter unit also outputs a / 1595 signal; The output terminals of the drive register U23 output the CTL1 signal, CTL2 signal, CTL3 signal and / EN signal respectively; The multi-level current output unit includes a relay group unit, a current sampling unit, a transformer TI1, a power amplifier unit, a power amplifier enable unit, and a DA signal amplitude control unit. The control terminals of the multi-level current output unit include control terminal A and control terminal B; The control terminal of the relay group unit constitutes the control terminal A of the multi-level current output unit, and the output terminal constitutes the output terminal of the multi-level current output unit. The relay group unit includes 3 relay groups. The coil control terminals of these 3 relay groups constitute the control terminals of the relay group unit. The coil control terminals of the 3 relay groups are all controlled in parallel through parallel signals, which consist of CTL1 signal, CTL2 signal and CTL3 signal. In the three relay groups, the common contacts of each group of relays are connected together to form a total of three common output terminals. These three common output terminals constitute the output terminals of the relay group unit. The normally open contacts of each group of relays constitute the relay input terminals of that group, forming a total of three relay input terminals. These three relay input terminals constitute the input terminals of the relay group unit. One relay input terminal is connected to pins 3, 4, and 5 of transformer TI1, and its corresponding common output terminal is connected to the current output interface; The other two relay input terminals are connected to pin 6 of transformer TI1. Their corresponding two common output terminals are connected to the current output interface and the other outputs the US signal and connects to the input terminal of the current sampling unit. The output terminals of the current sampling unit output FBI and FB signals respectively. The output terminal that outputs the FBI signal constitutes the current signal sampling terminal of the multi-level current output unit, and the FB signal is connected to the DA signal amplitude control unit. The DA signal amplitude control unit is used to control the output amplitude of the power amplifier unit; The DA signal amplitude control unit is connected to the power amplifier enable unit, pins 1 and 2 of transformer TI1, and the power amplifier unit, respectively. The test signal input terminal of the DA signal amplitude control unit constitutes the test terminal of the multi-level current output unit; The input terminal of the DA signal amplitude control unit constitutes the input terminal of the multi-level current output unit; The control terminal of the DA signal amplitude control unit constitutes the control terminal B of the multi-level current output unit, and the output terminal of the filter unit is also connected to the control terminal of the DA signal amplitude control unit. The output of the power amplifier unit is connected to pin 2 of transformer TI1.

6. The leakage current protection tester as described in claim 5, characterized in that: The DA signal generation unit includes a resistor array R49, an isolator U18, a resistor array R61, a DA chip U26, and a DA signal isolation and amplification unit; The input terminal of isolator U18 is connected to a set of I / O ports of the main controller through resistor array R49, and the output terminal is connected to the input terminal of DA chip U26 through resistor array R61. The output terminal of DA chip U26 is connected to DA signal amplification and isolation unit. DA signal amplification and isolation unit constitutes the output terminal of DA signal generation unit and outputs SIN signal. The connection terminal of resistor array R49 with the main controller constitutes the input terminal of DA signal generation unit. The DA signal amplitude control unit includes a first isolation unit, a DA chip U22, a second isolation unit, a differential amplifier U28A, a transformer signal amplification unit, and a power amplifier drive unit. The input terminal of the first isolation unit constitutes the input terminal of the DA signal amplitude control unit. The input terminal of the first isolation unit is connected to the output terminal of the DA signal amplification isolation unit, and the output terminal is connected to the input terminal of the DA chip U22. The control terminal of the DA chip U22 constitutes the control terminal of the DA signal amplitude control unit. The output terminal of the DA chip U22 is connected to the positive input terminal of the differential amplifier U28A through the second isolation unit. The FB signal is connected to the positive input terminal of the differential amplifier U28A. The negative input terminal of the differential amplifier U28A is connected to the output terminal of the transformer signal amplification unit, and the input terminal of the transformer signal amplification unit is connected to pin 1 of the transformer TI1. The differential amplifier U28A is also connected to pin 2 of transformer TI1 and the test signal input terminal of the DA signal amplitude control unit. The output terminal of the differential amplifier U28A is connected to the input terminal of the power amplifier drive signal unit. The control terminal of the power amplifier drive signal unit is connected to the power amplifier enable unit, and the output terminal is connected to the power amplifier unit.

7. A leakage current protection tester as described in claim 6, characterized in that: The current-to-AD conversion unit includes an amplifier unit, an AD chip U31, a resistor array R80, an isolator U29, and a resistor array R100. The input terminal of the amplifier unit constitutes the input terminal of the current-to-AD conversion unit. The input terminal of the amplifier unit is connected to the FBI signal, and the output terminal is connected to the AD chip U31. The output terminal of the AD chip U31 is connected to the input terminal of the isolator U29 through the resistor array R80. The output terminal of the isolator U29 is connected to the main controller through the resistor array R100. The connection terminal of the resistor array R100 and the main controller constitutes the output terminal of the current-to-AD conversion unit. The second reference voltage module includes a power supply chip U20, a first reference voltage generation unit, and a second reference voltage generation unit. The output terminal of the power supply chip U20 is connected to the first reference voltage generation unit and the second reference voltage generation unit respectively, and outputs a reference voltage Vre5V. The first reference voltage generation unit and the second reference voltage generation unit output reference voltages Vre2V and Vre10V respectively. The reference voltages Vre5V and Vre2V provide reference voltages for the AD chip U31 and the amplification unit respectively, and the reference voltage Vre10V provides a reference voltage for the DA chip U26.

8. The leakage current protection tester as described in claim 7, characterized in that: The fault detection unit includes operational amplifier U17A, operational amplifier U17B, resistors R38, R45, R37, R44, R46, R53, capacitor C68, operational amplifier U24A, capacitor C82, diode D3, resistor R58, diode D4, resistor R60, resistor R70, diode D8, resistor R71, resistor R75, resistor R87, resistor R83, LED D17, and transistor Q2. Resistors R37 and R38 are connected in series, with one end connected to the TEST signal from the multi-level current output unit and the other end connected to ground. Pin 2 of operational amplifier U17A is connected to the junction of resistors R37 and R38, pin 3 is connected to a +15V power supply via resistor R45, and pin 1 is connected to the positive terminal of diode D3. Pin 6 of operational amplifier U17B is connected to a -15V power supply via resistor R46, and pin 5 is connected to the operational amplifier... Pins 2 and 7 of operational amplifier U17A are connected to pin 1 of operational amplifier U17A. Resistor R44 is connected between pin 3 of operational amplifier U17A and pin 6 of operational amplifier U17B. Resistor R53 is the pull-up resistor for pin 1 of operational amplifier U17A. Capacitor C68 is connected in parallel with resistor R53. The cathode of diode D3 is connected to pin 2 of operational amplifier U24A. Resistor R58 is connected in parallel with diode D3. Diode D3 is also connected to the anode of diode D4. Pin 3 of operational amplifier U24A is connected to pin 6 of operational amplifier U17B. Pin 1 of operational amplifier U24A is connected to the anode of diode D8. The cathode of diode D8 is connected to pin 5 of operational amplifier U24B. Pin 6 of operational amplifier U24B is connected to a +15V power supply through resistor R70. Pin 7 outputs a VOLD signal. The cathode of diode D4 is connected to pin 6 of operational amplifier U24B through resistor R60. Pin 6 of operational amplifier U24B is also connected to an / EN signal. Pin 5 of operational amplifier U24B is connected to a -15V power supply through resistor R71, and resistor R75 is connected between pin 5 and pin 7 of operational amplifier U24B. Pin 7 of operational amplifier U24B is connected to the base of transistor Q2 through resistor R87. The emitter of transistor Q2 is connected to ground, and the collector is connected to isolator U18 through resistor array R61 to output a control signal FAIL. The positive terminal of LED D17 is connected to pin 7 of operational amplifier U24B via resistor R83, and the negative terminal is connected to ground.

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