Alternating current air switch tripping bypass self-contained system and method

Abstract

The system comprises an air switch, a contactor, a current transformer, a load and a printed circuit board, the air switch is respectively connected with the contactor, the current transformer, the load and the printed circuit board, the air switch is further connected with a three-phase power supply, and the three-phase power supply is connected with the contactor, the current transformer, the load and the printed circuit board. The contactor is connected with the printed circuit board, the current transformer is connected with the printed circuit board, the load is respectively connected with the contactor and the current transformer, the air switch comprises an original loop air switch and a bypass air switch, and the printed circuit board comprises an isolation operation amplification circuit, a micro-control unit and a contactor pull-in control circuit. The method comprises the following steps of system initialization, normal power supply monitoring, tripping fault detection, bypass air switch switching, fault signal alarm, original loop power supply recovery and system monitoring and maintenance. Normal work of the heater and the temperature and humidity controller in the terminal box is guaranteed, and the damage probability of the terminal box is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of power system automation and protection, in particular to an AC air switch tripping bypass self-contained device for a terminal box in a transformer substation. Background Art

[0002] The AC air switch is an important component in the power system, responsible for controlling the on and off of the current. However, the AC air switch in the terminal box in the substation often trips during long-term operation, causing the temperature and humidity controller of the heater in the terminal box to fail to operate normally, which in turn causes the terminal box to fail to dehumidify in time when the humidity is too high, resulting in safety risks such as rust inside the terminal box and short circuit and sparking of electrical components. In addition, the AC air switch inside the terminal box is in an outdoor switch environment, which is more severe than the indoor operating conditions, making the AC air switch in the terminal box more prone to tripping. When a trip occurs, not only will the workload of the operating personnel increase, but the equipment may also be damaged due to untimely handling, which will seriously reduce the service life of the equipment. Summary of the invention

[0003] In view of the above-mentioned problems, the present invention monitors the working status of the AC air switch in real time, and cooperates with the internal AC contactor, bypass self-contained circuit breaker and monitor of the bypass self-contained device to realize that after the AC air switch trips secretly, the bypass automatically provides power to ensure the normal operation of the internal equipment of the terminal box.

[0004] The technical solution of the present invention is as follows:

[0005] An AC air switch tripping bypass self-contained system comprises: an air switch, a contactor, a current transformer, a load and a printed circuit board, wherein the air switch is respectively connected to the contactor, the current transformer, the load and the printed circuit board, the air switch is also connected to a three-phase power supply, the contactor is connected to the printed circuit board, the current transformer is connected to the printed circuit board, the load is respectively connected to the contactor and the current transformer, the air switch comprises: an original circuit breaker and a bypass circuit breaker, the printed circuit board comprises: an isolation operational amplifier circuit, a micro control unit, a contactor pull-in control circuit and a cloud platform remote monitoring module, the isolation operational amplifier circuit is connected to the micro control unit, the micro control unit is respectively connected to the contactor pull-in control circuit and the cloud platform remote monitoring module, and the micro control unit comprises: a trip detection module, an overcurrent and leakage detection module and a GPIO interface.

[0006] Furthermore, the primary circuit breaker receives an input of a three-phase power supply and is connected to a load, and the bypass circuit breaker receives a power input from the primary circuit breaker and is connected to an isolation operational amplifier circuit.

[0007] Furthermore, the current transformer is connected to an overcurrent and leakage detection module.

[0008] Furthermore, the number of the contactor pull-in control circuit and the contactor is two, the two contactor pull-in control circuits are connected in parallel, the two contactors are connected in parallel, and the contactor pull-in control circuit is connected to the contactor.

[0009] Furthermore, the microcontroller unit is a 32-bit microcontroller of STMicroelectronics, model number is STM32F103C8T6.

[0010] Furthermore, it also includes a power module, which is connected to the printed circuit board.

[0011] Furthermore, the GPIO interface is also connected to an external alarm device, a temperature and humidity monitoring module, and a cloud platform remote monitoring module.

[0012] Furthermore, a delay control module is provided on the contactor.

[0013] An AC air switch stealth bypass self-prepared method based on the above-mentioned AC air switch stealth bypass self-prepared system comprises the following steps:

[0014] S1, system initialization: Check whether the air switch, contactor, current transformer, and micro control unit are working properly. The micro control unit performs initialization detection on the status of the air switch and bypass circuit breaker to confirm that both are in normal status;

[0015] S2. Normal power supply monitoring: When the original circuit breaker is closed, the load is powered by the original circuit breaker, the current transformer monitors the load current in real time, and transmits the signal to the micro control unit. The trip detection module and the overcurrent and leakage detection module in the micro control unit continuously monitor the current signal and leakage signal;

[0016] S3, trip fault detection: If the original circuit breaker trips unexpectedly, the trip detection module detects that the current is disconnected or the load current is abnormal. At the same time, the overcurrent and leakage detection module determines whether there is an overcurrent or leakage fault. The micro control unit analyzes the data received from the current transformer and the above detection module to confirm the specific type of fault;

[0017] S4, bypass circuit breaker switching: after confirming that the circuit breaker of the original circuit is tripped or fails, the control system of the microcontroller automatically activates the bypass switching operation, and the GPIO interface sends a signal to the contactor suction control circuit to control the contactor to suction and connect the bypass, and the load continues to be powered through the bypass circuit;

[0018] S5, Fault signal alarm: After the bypass switching is successful, the system sends a fault signal to the external alarm device or monitoring system through the micro control unit to remind the operator to pay attention to the tripping event;

[0019] S6, restore the original circuit power supply: if it is detected that the original circuit breaker resumes normal operation, the bypass is automatically disconnected, the load is powered by the original circuit breaker again, and the micro control unit controls the contactor to disconnect the bypass, restoring the system to normal state;

[0020] S7, System monitoring and maintenance: During bypass switching and after recovery, the system continues to monitor the operating status of the load in real time.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The contactor can automatically switch to bypass to provide power when the main circuit trips;

[0023] 2. The bypass circuit breaker is used to protect the bypass line and trip the line in case of a fault;

[0024] 3. The micro control unit can monitor the working condition of the main circuit in real time and send out a signal when a trip occurs, making it easy for operators to detect the trip during inspection.

[0025] The self-contained device for bypassing the AC air switch in the present invention ensures the normal operation of the heater and the temperature and humidity controller inside the terminal box, prevents the two devices in the terminal box from being damp and short-circuited, and avoids the occurrence of accidents. At the same time, the device has the characteristics of simple structure, easy installation, automatic processing, and automatic recovery. In summary, the development of the device has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The invention discloses a structural schematic diagram of an AC air switch bypass self-contained system.

[0027] Figure 2 The invention discloses a flow chart of a self-contained method for a self-contained system of an AC air switch stealth bypass.

[0028] Figure 3 The invention discloses a circuit diagram of a backup power supply of an AC air switch bypass self-contained system.

[0029] Figure 4 The invention discloses a circuit diagram of a micro control unit of an AC air switch bypass self-contained system.

[0030] Figure 5 The invention discloses a circuit diagram of a trip detection module of an AC air switch stealth trip bypass self-contained system.

[0031] Figure 6 The invention discloses a circuit diagram of an overcurrent and leakage detection module of an AC air switch stealth bypass self-contained system.

[0032] Figure 7The invention discloses a circuit diagram of an isolation operational amplifier circuit of an AC air switch stealth bypass self-contained system.

[0033] Figure 8 The invention discloses a circuit diagram of a contactor pull-in control circuit of an AC air switch stealth bypass self-contained system.

[0034] Fig. 9 The invention discloses a cloud platform remote monitoring circuit schematic diagram of an AC air switch bypass self-contained system. DETAILED DESCRIPTION

[0035] like Figure 1-2 As shown, an AC air switch tripping bypass self-contained system includes: an air switch, a contactor, a current transformer, a load and a printed circuit board, the air switch is respectively connected to the contactor, the current transformer, the load and the printed circuit board, the air switch is also connected to a three-phase power supply, the contactor is connected to the printed circuit board, the current transformer is connected to the printed circuit board, the load is respectively connected to the contactor and the current transformer, the air switch includes: an original circuit breaker and a bypass circuit breaker, the printed circuit board includes: an isolation operational amplifier circuit, a micro control unit, a contactor pull-in control circuit and a cloud platform remote monitoring module, the isolation operational amplifier circuit is connected to the micro control unit, the micro control unit is respectively connected to the contactor pull-in control circuit and the cloud platform remote monitoring module, the micro control unit includes: a trip detection module, an overcurrent and leakage detection module and a GPIO interface.

[0036] Preferably, the original circuit breaker receives an input of a three-phase power supply and is connected to a load, and the bypass circuit breaker receives a power input from the original circuit breaker and is connected to an isolation operational amplifier circuit.

[0037] Preferably, the current transformer is connected to an overcurrent and leakage detection module.

[0038] Preferably, the number of the contactor pull-in control circuit and the contactor is two, the two contactor pull-in control circuits are connected in parallel, the two contactors are connected in parallel, and the contactor pull-in control circuit is connected to the contactor.

[0039] Preferably, the microcontroller unit is a 32-bit microcontroller from STMicroelectronics, model number STM32F103C8T6.

[0040] Preferably, it further comprises a power module, wherein the power module is connected to the printed circuit board.

[0041] Preferably, the GPIO interface is also connected to an external alarm device, a temperature and humidity monitoring module and a cloud platform remote monitoring module.

[0042] Preferably, a delay control module is provided on the contactor.

[0043] An AC air switch stealth bypass self-prepared method based on the above-mentioned AC air switch stealth bypass self-prepared system comprises the following steps:

[0044] S1, system initialization: Check whether the air switch, contactor, current transformer, and micro control unit are working properly. The micro control unit performs initialization detection on the status of the air switch and bypass circuit breaker to confirm that both are in normal status;

[0045] S2. Normal power supply monitoring: When the original circuit breaker is closed, the load is powered by the original circuit breaker, the current transformer monitors the load current in real time, and transmits the signal to the micro control unit. The trip detection module and the overcurrent and leakage detection module in the micro control unit continuously monitor the current signal and leakage signal;

[0046] S3, trip fault detection: If the original circuit breaker trips unexpectedly, the trip detection module detects that the current is disconnected or the load current is abnormal. At the same time, the overcurrent and leakage detection module determines whether there is an overcurrent or leakage fault. The micro control unit analyzes the data received from the current transformer and the above detection module to confirm the specific type of fault;

[0047] S4, bypass circuit breaker switching: after confirming that the circuit breaker of the original circuit is tripped or fails, the control system of the microcontroller automatically activates the bypass switching operation, and the GPIO interface sends a signal to the contactor suction control circuit to control the contactor to suction and connect the bypass, and the load continues to be powered through the bypass circuit;

[0048] S5, Fault signal alarm: After the bypass switching is successful, the system sends a fault signal to the external alarm device or monitoring system through the micro control unit to remind the operator to pay attention to the tripping event;

[0049] S6, restore the original circuit power supply: if it is detected that the original circuit breaker resumes normal operation, the bypass is automatically disconnected, the load is powered by the original circuit breaker again, and the micro control unit controls the contactor to disconnect the bypass, restoring the system to normal state;

[0050] S7, System monitoring and maintenance: During bypass switching and after recovery, the system continues to monitor the operating status of the load in real time.

[0051] like Figure 3As shown in the figure, the backup power supply: a small AC-DC (AC to DC) power module is used to convert AC power into DC 5V, and then a linear regulator is used to stabilize the 5V to 3.3V to supply the MCU circuit and its peripheral circuits. The AC-DC power module first converts the input AC power (AC) into pulsating DC power (DC) through a rectifier. The rectifier is usually a diode or a rectifier bridge, which can separate the negative half-wave and positive half-wave of the AC power, so that the output current only flows in the positive or negative direction to form pulsating DC power. The rectified DC power still contains some AC components, which are called ripples. In order to remove these ripples, the AC-DC power module uses a filter to filter the DC power. The filter is usually a capacitor or inductor, which can absorb or smooth out the AC component in the DC power, making the output DC power more stable. The DC power after rectification and filtering may still not be the required stable voltage value. Therefore, the AC-DC power supply module also needs to perform voltage regulation. The voltage regulator (also called DC regulator) can monitor the output voltage and adjust its value as needed to ensure that the output DC power has a stable voltage and current.

[0052] The working principle of the AC-DC power supply module can be summarized as follows: the input AC power is first converted into pulsating DC power by a rectifier, and then the ripple is removed by a filter to obtain a stable DC power, and finally the voltage value is adjusted by a voltage regulator to obtain a stable DC power output. In this technical solution, the AC-DC module inputs AC220V and outputs DC5V. Since the power supply value of the subsequent circuit, such as the MCU circuit, is DC3.3V, the output of the AC-DC module also needs to be stabilized. In this technical solution, a linear regulator is used to achieve this function. When the input voltage or load current changes, the linear regulator will adjust the resistance of its internal pass element (such as a transistor) to keep the output voltage stable;

[0053] Component connection relationship: L and N are AC220V power supply interfaces, U13 and U16 are DC5V outputs, U15 is a linear voltage regulator, U13 and U16 need to be connected to the first and second pins of the linear voltage regulator respectively, diode D8 plays a role in further reducing the voltage, U15 pin 5 is the output pin of the linear voltage regulator, C26 and C27 are connected in parallel to play a filtering role, making the output voltage of the linear voltage regulator more stable.

[0054] like Figure 4As shown, the technical solution adopts STM32F103C8T6 as the microcontroller unit, which is a 32-bit microcontroller produced by STMicroelectronics. The basic circuit of the SMT32 single-chip microcomputer requires an external high-speed crystal oscillator circuit, a power-on reset circuit, a startup mode selection circuit, a power decoupling circuit and a program download circuit, among which C16 to C18 are decoupling circuits, RST is a reset circuit, X1 is a high-speed crystal oscillator, and H1 is a program download interface, which is connected to a PC for programming. U5 is an LCD screen interface. ADC1, ADC2, ADC3, and ADC4 are connected to the amplifier circuit output by the current transformer. ADC1, ADC2, and ADC3 are used to determine whether the original circuit breaker has an overcurrent trip, and ADC4 is used to determine whether the original circuit breaker has a leakage trip. ADC5, ADC6, and ADC7 are used to monitor the output voltage of the original circuit breaker, and OUT3 is connected to the control circuit of the contactor;

[0055] Determining whether the circuit breaker is tripping, overcurrent or leakage depends on the MCU's digital-to-analog conversion function (ADC). Its main function is to convert continuous analog voltage signals into discrete digital values ​​for easy processing by the microcontroller. The ADC module of STM32 is usually based on the successive approximation register (SAR) architecture. Its working principle is similar to that of a scale weighing. It is necessary to continuously adjust the combination of weights (binary bits) to approximate the actual mass of the object being measured (the actual voltage value of the analog signal). The ADC workflow includes the sampling stage and the conversion stage:

[0056] Sampling stage: The ADC holds the analog input signal on the sampling capacitor to stabilize the input voltage. This process can be viewed as charging the capacitor so that the voltage across the capacitor is equal to the voltage of the input signal.

[0057] Conversion phase: After the sampling phase, the ADC begins to compare the analog voltage with the reference voltage through a successive approximation algorithm. It starts with the highest bit and uses the comparator to determine whether the input voltage is above or below half of the reference voltage, and then determines the value of the bit based on the comparison result. Then, the ADC continues to perform similar comparisons on the next bit until all bits are determined;

[0058] Component connection relationship: U1 is the main control chip, its 20th and 44th pins are for power-on boot, resistors R6 and R16 are connected in series to the negative power supply, and the positive and negative power supplies are respectively Figure 33.3V and GND in. Pin 5 and pin 6 are external clock input pins, which need to be connected to both ends of crystal oscillator X1 and connected in series with C57 and C58 to the negative power supply. H1 is the program burning interface, which is connected to the debug pins SWCLK and SWDIO of the master control. The master control has 3 power pins, which need to be connected to the positive power supply. Parallel capacitors C16, C17, and C18 play a filtering role. ADC5, ADC6, and ADC7 are connected to the voltage signal detection interface, and ADC1, ADC2, ADC3, and ADC4 are connected to the current detection interface.

[0059] like Figure 5 As shown, the A, B, and C phase voltage signals are sampled from the output end of the circuit breaker, and the voltage is detected. If there is no voltage at the output end, it means that the circuit breaker is tripped. A series of resistors are connected in series to divide the high-voltage AC power, and then input into the isolation operational amplifier, which can protect the microcontroller circuit and compensate for the negative half cycle of the AC power for easy recognition by the microcontroller.

[0060] Component connection relationship: U4 is the A-phase voltage sampling isolation operational amplifier. The series resistors R3, R2, R1, R10, R13, R14, and R15 are used for voltage division. R10 is a sampling resistor that amplifies and isolates the voltage on R10 and connects to the ADC5 interface of the MCU. U7 is the B-phase voltage sampling isolation operational amplifier. The series resistors R19, R18, R17, R25, R29, R30, and R31 are used for voltage division. R25 is a sampling resistor that amplifies and isolates the voltage on R25 and connects to the ADC6 interface of the MCU. U8 is the C-phase voltage sampling isolation operational amplifier. The series resistors R34, R33, R32, R42, R48, R49, and R50 are used for voltage division. R42 is a sampling resistor that amplifies and isolates the voltage on R42 and connects to the ADC7 interface of the MCU. U14 is the power supply for the isolation operational amplifiers U4, U7, and U10, and acts as an isolation power supply.

[0061] like Figure 6 As shown, three current transformers are used to monitor the three-phase currents of A, B, and C. After the current transformer detects the current in the wire, it will sense the induced current according to a certain ratio, and then pass through the 10mR sampling resistor. A precision operational amplifier is used to amplify the voltage across the sampling resistor and output it to the ADC channel pin of the MCU. The current in the wire can be calculated according to the amplification factor, and then a current transformer is used to cover the four wires A, B, C, and N to detect whether leakage occurs;

[0062] Component connection relationship: U2 is the A-phase current transformer interface. When current flows through the A-phase line, a voltage will be generated on the sampling resistor R8, which is proportional to the current. After R8 is connected in parallel with capacitor C1, the high and low potential ends are connected to resistors R7 and R12 respectively, and are connected to the positive and negative input terminals of the operational amplifier U3 respectively. R5 and R12 form a feedback network. The output of the operational amplifier is limited by resistor R9 and voltage limited by diode D1, and then connected to the ADC1 interface of the MCU. U6 is the B-phase current transformer interface. When current flows through the B-phase line, a voltage will be generated on the sampling resistor R23, which is proportional to the current. After R23 is connected in parallel with capacitor C7, the high and low potential ends are connected to resistors R22 and R27 respectively, and are connected to the positive and negative input terminals of the operational amplifier U8 respectively. R21 and R27 form a feedback network. The output of the operational amplifier is limited by resistor R24 ​​and voltage limited by diode D3, and then connected to the ADC2 interface of the MCU. U11 is the C-phase current transformer interface. When current flows through the B-phase line, a voltage will be generated on the sampling resistor R45. The voltage is proportional to the current. After R45 is connected in parallel with capacitor C22, the high and low potential ends are connected to resistors R44 and R47 respectively, and are connected to the positive and negative input terminals of the operational amplifier U12 respectively. R41 and R47 form a feedback network. The output of the operational amplifier is limited by resistor R46. Diode D6 limits the voltage and is then connected to the ADC3 interface of the MCU. U17 is a leakage current detection interface. When leakage occurs, a voltage will be generated on the sampling resistor R54, which is proportional to the current. After R54 is connected in parallel with capacitor C29, the high and low potential ends are connected to resistors R53 and R56 respectively, and are respectively connected to the positive and negative input terminals of the operational amplifier U18. R52 and R56 form a feedback network. The output of the operational amplifier is limited by resistor R55 and limited by diode D9, and then connected to the ADC4 interface of the MCU.

[0063] like Figure 7 As shown, in order to ensure the accuracy of detection, the operational amplifier uses a more accurate power supply. In this technical solution, a power reference chip is used, which can output pure DC3V and DC1.25V voltages;

[0064] Component connection relationship: +3V_A is connected to the 5th pin of operational amplifiers U3, U8, U12, and U18, and is filtered by capacitors C6, C13, C24, and C31. 1.25VREF is connected to resistors R4, R20, R40, and R51 and then connected to the 3rd pin of operational amplifiers U3, U8, U12, and U18.

[0065] like Figure 8As shown in the figure, the connection relationship of each component in the contactor pull-in control circuit is as follows: OUT3 is connected to the OUT3 interface of the MCU after being limited by the resistor R38. When the OUT3 of the MCU outputs a low level, the phototransistor U9 is turned on, the base of the transistor Q1 is pulled low, its source and collector are turned on, the normally open contact of the relay RLY1 is closed, INPUIT3 and OUTPUT3 are equivalent to the power switch of the contactor coil, INPUIT3 and OUTPUT3 are turned on, the contactor is pulled in, R39 is a pull-up resistor, and R37 is a current limiting resistor.

[0066] like Fig. 9 As shown, the cloud platform remote monitoring module is an LTE-FDD / LTE-TDD / WCDMA / GSM wireless communication module (U26) with diversity reception function, supporting GPRS (network data connection and other functions, providing high-speed data transmission services;

[0067] The typical power supply value of U26 is 3.8V. The design uses a synchronous buck converter (U27) to provide it. The input voltage is 5V, and the output voltage is adjusted by forming a feedback network through R66 and R67. Vout = 0.768*(1+R66 / R67). C41, C42, and C53 are input filter capacitors, and C39 and C40 are output filters. Pin 5 of U26 is output enable, which is valid at high level. It is connected to a 5V voltage after current limiting by R65. Pin 6 of U26 provides current for the high-side gate drive. A 0.1uf capacitor C38 must be connected between pin 5 and pin 2;

[0068] The 17th pin of U26 is the reset pin of the sim card, the 16th pin is the clock pin of the sim card, the 15th pin is the data pin of the sim card, and the 14th pin is the power pin of the sim card, which can automatically determine whether it is a 1.8V sim card or a 3.0V sim card. The 13th pin is for sim card insertion and removal detection. The 10th pin is the negative power supply of the sim card. The above pins are connected to the RST, CLK, DATA, VCC, CD, and I / O pins of CARD1 respectively. CADR1 is the sim card holder;

[0069] The 20th pin of U26 is the reset button, connected to SW1, and connected in parallel with the electrostatic protection device D12. The 21st pin is the power button, connected to SW2, and connected in parallel with the electrostatic protection device D13.

[0070] Pins 67 and 68 of U26 are the sending and receiving pins of the main serial port, and need to be cross-connected with the sending and receiving pins of the MCU's serial port. However, the U26 serial port level is 1.8V, and the MCU serial port level is 3.3V. Use Q3 and Q4 to achieve level conversion, VDD_EXT continuously outputs 1.8V level, when the MCU serial port sending pin UART_TXD outputs a low level, Q4 is turned on, and the U26 main serial port receives a low level. When the MCU sending pin UART_TXD outputs a high level, Q4 is turned off, the U26 main serial port receives a 1.8V level, and R70 and R72 are pull-up resistors. When the U26 sending pin (TXD) outputs a low level, Q3 is turned on, and the MCU receives a low level. When the U26 sending pin (TXD) outputs 1.8V, Q3 is turned off, the MCU receives a high level, and R69 and R71 are pull-up resistors. This process is the serial port communication process between the MCU and U26;

[0071] Pin 49 of U26 is the main antenna interface, and pin 35 of U26 is the diversity antenna interface, which are connected to the RF1 and RF2 antenna sockets respectively. The three 0 ohm resistors R73, R72, and R75 form the reserved solder joints of the Π-shaped filter circuit, and the same applies to R76, R77, and R78.

[0072] Although the specific implementation of the present invention is introduced above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that those non-creative modifications or equivalent replacements of the technical solution of the present invention, which do not depart from the protection scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims

1. An AC air switch bypass self-contained system, characterized in that: include: An air switch, a contactor, a current transformer, a load and a printed circuit board, wherein the air switch is respectively connected to the contactor, the current transformer, the load and the printed circuit board, the air switch is also connected to a three-phase power supply, the contactor is connected to the printed circuit board, the current transformer is connected to the printed circuit board, the load is respectively connected to the contactor and the current transformer, the air switch comprises: an original circuit breaker and a bypass circuit breaker, the printed circuit board comprises: an isolation operational amplifier circuit, a micro control unit, a contactor pull-in control circuit and a cloud platform remote monitoring module, the isolation operational amplifier circuit is connected to the micro control unit, the micro control unit is respectively connected to the contactor pull-in control circuit and the cloud platform remote monitoring module, and the micro control unit comprises: a trip detection module, an overcurrent and leakage detection module and a GPIO interface.

2. The AC air switch bypass self-contained system according to claim 1 is characterized in that: The primary circuit breaker receives an input of a three-phase power supply and is connected to a load, and the bypass circuit breaker receives a power input from the primary circuit breaker and is connected to an isolation operational amplifier circuit.

3. The AC air switch bypass self-contained system according to claim 1 is characterized in that: The current transformer is connected to the overcurrent and leakage detection module.

4. The AC air switch bypass self-contained system according to claim 1 is characterized in that: The number of the contactor pull-in control circuit and the contactor is two, the two contactor pull-in control circuits are connected in parallel, the two contactors are connected in parallel, and the contactor pull-in control circuit is connected to the contactor.

5. The AC air switch bypass self-contained system according to claim 1 is characterized in that: The microcontroller unit is a 32-bit microcontroller from STMicroelectronics, model number STM32F103C8T6.

6. The AC air switch bypass self-contained system according to claim 1, characterized in that: It also includes a power supply module, and the backup power supply module is connected to the printed circuit board.

7. The AC air switch bypass self-contained system according to claim 1, characterized in that: The GPIO interface is also connected to an external alarm device, a temperature and humidity monitoring module, and a cloud platform remote monitoring module.

8. The AC air switch bypass self-contained system according to claim 1, characterized in that: The contactor is provided with a delay control module.

9. An AC air switch stealth bypass self-prepared method based on the AC air switch stealth bypass self-prepared system of claim 1, characterized in that: The following steps are involved: S1, system initialization: Check whether the air switch, contactor, current transformer, and micro control unit are working properly. The micro control unit performs initialization detection on the status of the air switch and bypass circuit breaker to confirm that both are in normal status; S2. Normal power supply monitoring: When the original circuit breaker is closed, the load is powered by the original circuit breaker, the current transformer monitors the load current in real time, and transmits the signal to the micro control unit. The trip detection module and the overcurrent and leakage detection module in the micro control unit continuously monitor the current signal and leakage signal; S3, trip fault detection: If the original circuit breaker trips unexpectedly, the trip detection module detects that the current is disconnected or the load current is abnormal. At the same time, the overcurrent and leakage detection module determines whether there is an overcurrent or leakage fault. The micro control unit analyzes the data received from the current transformer and the above detection module to confirm the specific type of fault; S4, bypass circuit breaker switching: after confirming that the circuit breaker of the original circuit is tripped or fails, the control system of the microcontroller automatically activates the bypass switching operation, and the GPIO interface sends a signal to the contactor suction control circuit to control the contactor to suction and connect the bypass, and the load continues to be powered through the bypass circuit; S5, Fault signal alarm: After the bypass switching is successful, the system sends a fault signal to the external alarm device or monitoring system through the micro control unit to remind the operator to pay attention to the tripping event; S6, restore the original circuit power supply: if it is detected that the original circuit breaker resumes normal operation, the bypass is automatically disconnected, the load is powered by the original circuit breaker again, and the micro control unit controls the contactor to disconnect the bypass, restoring the system to normal state; S7, System monitoring and maintenance: During bypass switching and after recovery, the system continues to monitor the operating status of the load in real time.

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