Intelligent three-phase contactor

Abstract

The invention provides an intelligent three-phase contactor. Comprising a processor, the processor is connected with a power conversion circuit, and the processor is connected with a tripping interface, a reconnection port, a drive control circuit and a health monitoring circuit through I / O ports and connected with an AD acquisition chip through an SPI port; the driving control circuit and the health monitoring circuit are respectively connected with a three-phase alternating current contactor through a current sensor and an optocoupler, and the AD acquisition chip respectively acquires three-phase voltage and current of the three-phase alternating current contactor through three voltage acquisition circuits and three current acquisition circuits. In the switching-on process of the contactor, the processor can monitor the voltage of the contactor, and when the voltage exceeds the limit, the driving controller circuit is controlled to disconnect the contactor, so that overvoltage and undervoltage protection is realized, and the contactor load is effectively prevented from being damaged due to unstable voltage. Moreover, the contactor can be connected with external equipment, and the working states of the contactor, such as voltage, current and frequency, can be displayed through the external equipment.

Description

Technical Field

[0001] The invention relates to an intelligent three-phase contactor. Background Art

[0002] At present, ordinary contactors are often used in power system applications to control the on and off of load circuits, but the circuit current, voltage and three-phase status cannot be collected, and when the load or power supply fails, effective protection cannot be performed, thereby damaging the power supply or load. However, in the application of aviation power systems and ground power systems, it is often necessary to control the three-phase AC power supply and collect the system circuit status and protect against overvoltage, overcurrent, etc. Most of the current power supply protection and load protection use separate protection, that is, circuit breakers or fuses are used to protect the load circuit. This protection method is large in size and poor in operability. It only protects the current but not the voltage or three-phase sequence. It cannot effectively upload the circuit and contactor's own information, which has great limitations on practical applications. For example, CN106026787A discloses a 5-level discrete frequency conversion soft start device based on power factor angle closed-loop control. The current and voltage at the front end of the contactor are collected through a synchronous signal acquisition circuit and transmitted to the single-chip microcomputer for monitoring. When the voltage and current exceed the limit, the contactor is disconnected to protect the motor. However, it is unable to monitor the input and output frequencies of the contactor, making it impossible to determine the cause of the voltage and current exceeding the limit. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides an intelligent three-phase contactor.

[0004] The present invention is achieved through the following technical solutions.

[0005] The present invention provides an intelligent three-phase contactor; comprising a processor, the processor and a power conversion circuit, the processor is respectively connected to a tripping interface, a reconnection interface, a drive control circuit, and a health monitoring circuit through an I / O port, and is connected to an AD acquisition chip through an SPI port; the drive control circuit and the health monitoring circuit are respectively connected to the three-phase AC contactor through a current sensor and an optical coupler, the AD acquisition chip respectively acquires the three-phase voltage and current of the three-phase AC contactor through three voltage acquisition circuits and three current acquisition circuits; the processor also acquires the input and output frequencies of each phase of the three-phase AC contactor through a frequency acquisition circuit, and the power conversion circuit converts a bias power supply into 5V, 3.3V and 1.25V reference voltages and supplies power to the devices in the contactor respectively.

[0006] The power conversion circuit includes a DC / DC power supply, the input end of the DC / DC power supply is connected to the bias power supply, and the output end outputs a 5V power supply to an LDO power supply and two isolated DC / DC power supplies. The LDO power supply converts the 5V power supply into a 3.3V power supply and inputs it into a processor and a voltage reference power supply. The voltage reference converts the 3.3V power supply into a 1.25V reference voltage to provide a reference voltage for a three-phase voltage acquisition circuit. The two isolated DC / DC power supplies respectively power operational amplifiers in the three-phase voltage acquisition circuit and the three-phase current acquisition circuit. The bias power supply is also connected to a drive control circuit.

[0007] The voltage acquisition circuit includes an isolation amplifier U1, an INP terminal of the isolation amplifier U1 is connected to the three-phase AC contactor through resistors R2 and R3 and is grounded through resistor R1, and a REFIN terminal is connected to a 1.25V reference voltage; resistors R1, R2, and R3 convert the input voltage to below 1.2V and input it to the isolation amplifier U1, and the isolation amplifier U1 converts the received voltage into an AC isolation voltage based on 1.25V and inputs it to the AD acquisition chip through the OUT terminal.

[0008] The VDD1 and VDD2 terminals of the isolation amplifier U1 are connected to 5V and 3.3V voltages respectively, the GND1 and GND2 terminals are grounded respectively, the resistors C1 and C2 are connected in parallel between the VDD1 and GND1 terminals, and the resistors C3 and C4 are connected in parallel between the VDD2 and GND2 terminals; the resistors R1, R2, and R3 are all high-precision voltage-dividing resistors.

[0009] The current acquisition circuit includes an isolation amplifier U2, and the INP terminal of the isolation amplifier U2 is connected to the three-phase AC contactor through a resistor R4, and one end of the resistor R4 connected to the isolation amplifier is also connected to a current output terminal; the current of the three-phase AC contactor passes through the resistor R4 and then flows out through the current output terminal, forming a millivolt voltage signal on the resistor R4, and the millivolt voltage signal is converted into an isolation voltage value based on 1.45V±1.2V by the isolation amplifier U2 and then input into the AD acquisition chip through the OUT terminal.

[0010] The VDD1 and VDD2 terminals of the isolation amplifier U2 are connected to 5V and 3.3V voltages respectively, the GND1 and GND2 terminals are grounded respectively, the resistors C5 and C6 are connected in parallel between the VDD1 and GND1 terminals, and the resistors C7 and C8 are connected in parallel between the VDD2 and GND2 terminals.

[0011] There are six frequency acquisition circuits, which are respectively connected to the three phases of the input end and the three phases of the output end of the three-phase AC contactor; the frequency acquisition circuit includes an optocoupler U3, the positive pole of the input end of the optocoupler U3 is respectively connected to the resistor R6 and the resistor R8, the other ends of the resistor R6 and the resistor R8 are respectively connected to the resistor R5 and the resistor R7, the other ends of the resistor R5 and the resistor R7 are connected to the single phase of the input or output end of the three-phase AC contactor, the negative pole of the input end of the optocoupler U3 is connected to the N phase, and a diode D1 is reversely connected between the positive and negative poles of the input end of the optocoupler U3, the positive pole of the output end is connected to a 3.3V voltage, the negative pole of the output end outputs a square wave pulse to the processor, and is grounded through a resistor R9.

[0012] The health monitoring circuit includes a coil current monitoring circuit and a contactor connection times acquisition circuit. The coil current monitoring circuit includes a current sensor U5. The IP-port of the current sensor U5 is connected to the three-phase AC contactor, the IP+ port is connected to the drive control circuit, the VCC port is connected to the 3.3V power supply, and the OUT port outputs a voltage signal to the processor; the connection times acquisition circuit includes an optocoupler U7. The negative pole of the input end of the optocoupler U7 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the three-phase AC contactor, the positive pole of the input end of the optocoupler U7 is connected to the 28V power supply through a resistor R11, the positive pole of the output end is connected to the 3.3V voltage, the negative pole of the output end is connected to the processor, and is grounded through a resistor R12.

[0013] The drive control circuit includes a solid relay, the positive input terminal of the solid relay is connected to a 3.3V voltage, the negative input terminal is connected to a control signal of a processor, the positive output terminal is connected to a 28V power supply, and the negative output terminal is connected to the IP+ terminal of the current sensor U5.

[0014] The processor also communicates with the outside through a CAN transceiver.

[0015] The beneficial effect of the present invention is that during the contactor connection process, the processor can monitor the voltage of the contactor, and when the voltage exceeds the limit, the drive control circuit is controlled to disconnect the contactor, thereby realizing overvoltage and undervoltage protection, and effectively preventing the contactor load from being damaged due to unstable voltage. In addition, the contactor can be connected to an external device, and the working status of the contactor such as voltage, current, and frequency can be displayed through the external device.

[0016] The beneficial effects of the present application are as follows: when the front-end voltage exceeds the set maximum voltage, the contactor cannot be controlled to be connected and the overvoltage state is fed back to the outside through the bus and I / O interface. If the voltage exceeds the set maximum voltage during the connection process, the contactor is immediately disconnected to achieve overvoltage protection, which can effectively avoid damage to the load due to excessive voltage. When the front-end voltage is lower than the set minimum voltage, the contactor cannot be controlled to be connected and the undervoltage state is fed back to the outside through the bus and I / O interface. If the voltage is lower than the set minimum voltage during the connection process, the contactor is immediately disconnected to achieve undervoltage protection, which can effectively avoid unstable operation of the load due to too low voltage. When the load current is greater than the rated load current, the overcurrent protection will be triggered, and after I 2 After the inverse time curve of t, the contactor circuit is disconnected to protect the rear-end load. When the front-end three-phase power phase is missing or the phase is wrong, it can be detected by the present invention and the contactor shutdown command can be executed to protect the load and power supply. The present invention can upload the voltage, current, frequency and working status to the external device to achieve the effect of human-computer interaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of the present invention;

[0018] Figure 2 It is a schematic diagram of the voltage acquisition circuit principle of the present invention;

[0019] Figure 3 It is a schematic diagram of the principle of the current collection circuit of the present invention;

[0020] Figure 4 It is a schematic diagram of the frequency acquisition circuit principle of the present invention;

[0021] Figure 5 It is a schematic diagram of the driving control circuit and health monitoring circuit of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0023] like Figure 1As shown, an intelligent three-phase contactor can perform overvoltage protection, undervoltage protection, overcurrent protection, phase loss and phase mismatch protection on the load circuit, front and rear frequency monitoring, front-end voltage monitoring, three-phase circuit current monitoring, contactor coil current monitoring, contactor connection times monitoring and parameter configuration and memory, including a processor, the processor and a power conversion circuit, the processor is connected to the trip interface, reconnection interface, drive control circuit, and health monitoring circuit through I / O ports, and is connected to the AD acquisition chip through the SPI port; the drive control circuit and the health monitoring circuit are connected to the three-phase AC contactor through current sensors and optocouplers, respectively, and the AD acquisition chip collects the three-phase voltage and current of the three-phase AC contactor through three voltage acquisition circuits and three current acquisition circuits respectively; the processor also collects the input and output frequencies of each phase of the three-phase AC contactor through a frequency acquisition circuit, and the power conversion circuit converts the bias power supply into 5V, 3.3V and 1.25V reference voltages and supplies power to the devices in the contactor respectively.

[0024] The processor transmits and controls data with the outside through the CAN bus peripherals, and configures and memorizes parameters through the IIC bus and the EEPROM power-off storage chip, which mainly stores the undervoltage point, overvoltage point, overcurrent point, rated current and device number of the contactor. The AD acquisition chip refreshes each analog quantity in real time, such as coil current, front-end voltage, loop current, etc., and converts each analog quantity into a digital quantity through the SPI interface and sends it to the processor for analysis and calculation. The processor controls the solid-state relay through the I / O pin and drives the contactor coil to work, monitors the contactor connection status through the optocoupler feedback, and monitors the input and output frequency through the input capture pin.

[0025] The power conversion circuit includes a DC / DC power supply, the input end of the DC / DC power supply is connected to the bias power supply, and the output end outputs 5V power to the LDO power supply and two isolated DC / DC power supplies. The LDO power supply converts the 5V power supply into a 3.3V power supply and inputs it into the processor and the voltage reference power supply. The voltage reference converts the 3.3V power supply into a 1.25V reference voltage to provide a reference voltage for the three-phase voltage acquisition circuit. The two isolated DC / DC power supplies respectively power the operational amplifiers in the three-phase voltage acquisition circuit and the three-phase current acquisition circuit. The bias power supply is also connected to the drive control circuit.

[0026] like Figure 2As shown, the voltage acquisition circuit includes an isolation amplifier U1, the INP terminal of the isolation amplifier U1 is connected to the three-phase AC contactor through resistors R2 and R3 and grounded through resistor R1, and the REFIN terminal is connected to the 1.25V reference voltage; resistors R1, R2, and R3 convert the input voltage to below 1.2V and input it to the isolation amplifier U1, and the isolation amplifier U1 converts the received voltage to an AC isolation voltage based on 1.25V and inputs it to the AD acquisition chip through the OUT terminal. The 115V AC is divided to less than 1.2V by high-precision voltage-dividing resistors R1, R2, and R3, and the AC voltage is converted to an AC isolation voltage based on 1.25V to the OUT terminal for the acquisition chip to collect and transmit to the processor for calculation. The current signal is converted into a voltage signal through a high-precision, low-resistance sampling resistor R4, and isolated and collected through the isolation amplifier U2, and the current signal is converted into a signal based on the base point voltage for the acquisition chip to collect and transmit to the processor for calculation.

[0027] The current acquisition circuit includes an isolation amplifier U2, and the INP terminal of the isolation amplifier U2 is connected to the three-phase AC contactor through a resistor R4, and one end of the resistor R4 connected to the isolation amplifier is also connected to a current output terminal; the current of the three-phase AC contactor passes through the resistor R4 and then flows out through the current output terminal, forming a millivolt voltage signal on the resistor R4, and the millivolt voltage signal is converted into an isolation voltage value based on 1.45V±1.2V by the isolation amplifier U2 and then input into the AD acquisition chip through the OUT terminal.

[0028] The voltage and current acquisition circuit is used to collect the front-end power supply voltage and the rear-end load current of the intelligent three-phase contactor. When the front-end voltage is undervoltage, when the front-end voltage is overvoltage, when the loop current is overcurrent, the intelligent three-phase contactor can cut off the load loop in time to achieve the purpose of load protection.

[0029] The VDD1 and VDD2 terminals of the isolation amplifier U2 are connected to 5V and 3.3V voltages respectively, the GND1 and GND2 terminals are grounded respectively, the resistors C5 and C6 are connected in parallel between the VDD1 and GND1 terminals, and the resistors C7 and C8 are connected in parallel between the VDD2 and GND2 terminals.

[0030] There are six frequency acquisition circuits, which are respectively connected to the three phases of the input end and the three phases of the output end of the three-phase AC contactor; the frequency acquisition circuit includes an optocoupler U3, the positive pole of the input end of the optocoupler U3 is respectively connected to the resistor R6 and the resistor R8, the other ends of the resistor R6 and the resistor R8 are respectively connected to the resistor R5 and the resistor R7, the other ends of the resistor R5 and the resistor R7 are connected to the single phase of the input or output end of the three-phase AC contactor, the negative pole of the input end of the optocoupler U3 is connected to the N phase, and a diode D1 is reversely connected between the positive and negative poles of the input end of the optocoupler U3, the positive pole of the output end is connected to a 3.3V voltage, the negative pole of the output end outputs a square wave pulse to the processor, and is grounded through a resistor R9. The input voltage is limited by the voltage-dividing resistors R5, R6, R7, and R8, and then forms a loop with the N phase through the front end of the optocoupler U3. The diode D1 converts the full wave into a half wave. The resistor R9 is a pull-down resistor to reduce line interference. The back end of the optocoupler U3 isolates and outputs a square wave pulse for the processor input capture pin to collect. The rising edge interval time is calculated to deduce the actual frequency of the front and back ends. The frequency acquisition circuit is used to collect the front and back end frequencies of the intelligent three-phase contactor. The front end frequency is used for three-phase phase sequence detection, phase loss and phase mismatch protection, and three-phase current and voltage sampling times. The back end frequency acquisition is used to detect whether there is power at the back end of the intelligent three-phase contactor based on the collected frequency range.

[0031] The health monitoring circuit includes a coil current monitoring circuit and a contactor connection times acquisition circuit. The coil current monitoring circuit includes a current sensor U5. The IP- port of the current sensor U5 is connected to the three-phase AC contactor, the IP+ port is connected to the drive control circuit, the VCC port is connected to the 3.3V power supply, and the OUT port outputs a voltage signal to the processor; the connection times acquisition circuit includes an optocoupler U7, the negative pole of the input end of the optocoupler U7 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the three-phase AC contactor, the positive pole of the input end of the optocoupler U7 is connected to the 28V power supply through a resistor R11, the positive pole of the output end is connected to the 3.3V voltage, the negative pole of the output end is connected to the processor, and is grounded through a resistor R12. The drive control circuit includes a solid relay, the positive pole of the input end of the solid relay is connected to the 3.3V voltage, the negative pole of the input end is connected to the control signal of the processor, the positive pole of the output end is connected to the 28V power supply, and the negative pole of the output end is connected to the IP+ end of the current sensor U5. The health monitoring circuit effectively controls the contactor coil and collects the coil current. When the coil current is continuously greater than the holding current, the contactor can be protected. The health monitoring can monitor the number of contactor operations and issue an alarm when the upper limit of the number of on and off times is reached.

[0032] The drive control and health monitoring principles of the present invention are as follows: Figure 5As shown, the processor controls the contactor to be turned on and off by controlling the high and low levels of the control pin. When the control pin is at a high level, the solid relay U4 is turned off and the contactor is turned off. When the control pin is at a low level, the current flows through the resistor R10 through the back end of the solid relay U4 to conduct 28V electricity from the current sensor U5 to the positive end of the contactor coil to drive the contactor to be turned on. Since the contactor starting current can reach 4A and the current is maintained at about 170mA, a solid relay U4 with a rated current of 8A is used for driving in order to design a margin. Health monitoring is mainly divided into coil current monitoring and contactor connection times monitoring. Since the contactor starting current can reach 4A, a 5A current sensor is used for current monitoring. The coil current is converted into a voltage signal and output to the acquisition chip for the processor to perform data calculations. Capacitor C5 is a filter capacitor to prevent power supply interference fluctuations from reducing reliability. When the contactor is connected, the auxiliary contact will be connected to the 28V power supply ground and form a loop with the current limiting resistor R11, optocoupler U7 and diode D2, so that the back end of the optocoupler U7 outputs a high level for the processor to collect and record the number of connections. Resistor R12 is a pull-down resistor and is in a low level state when initialized. Diode D2 plays a role in preventing reverse.

[0033] The processor also communicates with the outside through a CAN transceiver.

[0034] When the front-end voltage exceeds the set maximum voltage, the contactor cannot be controlled to connect and the overvoltage status is fed back to the outside through the bus and I / O interface. If the voltage exceeds the set maximum voltage during the connection process, the contactor is immediately disconnected to achieve overvoltage protection, which can effectively avoid damage to the load due to excessive voltage. When the front-end voltage is lower than the set minimum voltage, the contactor cannot be controlled to connect and the undervoltage status is fed back to the outside through the bus and I / O interface. If the voltage is lower than the set minimum voltage during the connection process, the contactor is immediately disconnected to achieve undervoltage protection, which can effectively avoid unstable operation of the load due to too low voltage. When the load current is greater than the rated load current, the overcurrent protection will be triggered. After I 2 After the inverse time curve of t, the contactor circuit is disconnected to protect the rear-end load. When the front-end three-phase power phase is missing or the phase is wrong, it can be detected by the present invention and the contactor shutdown command can be executed to protect the load and power supply. The present invention can upload the voltage, current, frequency and working status to the external device to achieve the effect of human-computer interaction.

Claims

1. An intelligent three-phase contactor, characterized in that: The invention comprises a processor, the processor and a power conversion circuit, wherein the processor is respectively connected to a tripping interface, a reconnection interface, a drive control circuit and a health monitoring circuit through an I / O port, and is connected to an AD acquisition chip through an SPI port; the drive control circuit and the health monitoring circuit are respectively connected to a three-phase AC contactor through a current sensor and an optical coupler, and the AD acquisition chip respectively acquires the three-phase voltage and current of the three-phase AC contactor through three voltage acquisition circuits and three current acquisition circuits; the processor also acquires the input and output frequency of each phase of the three-phase AC contactor through a frequency acquisition circuit, and the power conversion circuit converts the bias power supply into 5V, 3.3V and 1.25V reference voltages and supplies power to the devices in the contactor respectively.

2. The intelligent three-phase contactor according to claim 1, characterized in that: The power conversion circuit includes a DC / DC power supply, the input end of the DC / DC power supply is connected to the bias power supply, and the output end outputs a 5V power supply to an LDO power supply and two isolated DC / DC power supplies. The LDO power supply converts the 5V power supply into a 3.3V power supply and inputs it into a processor and a voltage reference power supply. The voltage reference converts the 3.3V power supply into a 1.25V reference voltage to provide a reference voltage for a three-phase voltage acquisition circuit. The two isolated DC / DC power supplies respectively power operational amplifiers in the three-phase voltage acquisition circuit and the three-phase current acquisition circuit. The bias power supply is also connected to a drive control circuit.

3. The intelligent three-phase contactor according to claim 1, characterized in that: The voltage acquisition circuit includes an isolation amplifier U1, an INP terminal of the isolation amplifier U1 is connected to the three-phase AC contactor through resistors R2 and R3 and is grounded through resistor R1, and a REFIN terminal is connected to a 1.25V reference voltage; resistors R1, R2, and R3 convert the input voltage to below 1.2V and input it to the isolation amplifier U1, and the isolation amplifier U1 converts the received voltage into an AC isolation voltage based on 1.25V and inputs it to the AD acquisition chip through the OUT terminal.

4. The intelligent three-phase contactor according to claim 3, characterized in that: The VDD1 and VDD2 terminals of the isolation amplifier U1 are connected to 5V and 3.3V voltages respectively, the GND1 and GND2 terminals are grounded respectively, the resistors C1 and C2 are connected in parallel between the VDD1 and GND1 terminals, and the resistors C3 and C4 are connected in parallel between the VDD2 and GND2 terminals; the resistors R1, R2, and R3 are all high-precision voltage-dividing resistors.

5. The intelligent three-phase contactor according to claim 1, characterized in that: The current collection circuit includes an isolation amplifier U2, an INP terminal of the isolation amplifier U2 is connected to the three-phase AC contactor through a resistor R4, and one end of the resistor R4 connected to the isolation amplifier is also connected to a current output terminal; The current of the three-phase AC contactor passes through the resistor R4 and then flows out through the current output terminal, forming a millivolt voltage signal on the resistor R4. The millivolt voltage signal is converted into an isolation voltage value based on 1.45V±1.2V by the isolation amplifier U2 and then input into the AD acquisition chip through the OUT terminal.

6. The intelligent three-phase contactor according to claim 5, characterized in that: The VDD1 and VDD2 terminals of the isolation amplifier U2 are connected to 5V and 3.3V voltages respectively, the GND1 and GND2 terminals are grounded respectively, the resistors C5 and C6 are connected in parallel between the VDD1 and GND1 terminals, and the resistors C7 and C8 are connected in parallel between the VDD2 and GND2 terminals.

7. The intelligent three-phase contactor according to claim 1, characterized in that: There are six frequency acquisition circuits, and the six frequency acquisition circuits are respectively connected to the three phases of the input end and the three phases of the output end of the three-phase AC contactor; the frequency acquisition circuit includes an optocoupler U3, the positive pole of the input end of the optocoupler U3 is respectively connected to the resistor R6 and the resistor R8, the other ends of the resistor R6 and the resistor R8 are respectively connected to the resistor R5 and the resistor R7, the other ends of the resistor R5 and the resistor R7 are connected to the single phase of the input or output end of the three-phase AC contactor, the negative pole of the input end of the optocoupler U3 is connected to the N phase, and a diode D1 is reversely connected between the positive and negative poles of the input end of the optocoupler U3, the positive pole of the output end is connected to a 3.3V voltage, and the negative pole of the output end outputs a square wave pulse to the processor and is grounded through a resistor R9.

8. The intelligent three-phase contactor according to claim 1, characterized in that: The health monitoring circuit includes a coil current monitoring circuit and a contactor connection times acquisition circuit. The coil current monitoring circuit includes a current sensor U5. The IP-port of the current sensor U5 is connected to the three-phase AC contactor, the IP+ port is connected to the drive control circuit, the VCC port is connected to the 3.3V power supply, and the OUT port outputs a voltage signal to the processor; the connection times acquisition circuit includes an optocoupler U7. The negative pole of the input end of the optocoupler U7 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to the three-phase AC contactor, the positive pole of the input end of the optocoupler U7 is connected to the 28V power supply through a resistor R11, the positive pole of the output end is connected to the 3.3V voltage, the negative pole of the output end is connected to the processor, and is grounded through a resistor R12.

9. The intelligent three-phase contactor according to claim 1, characterized in that: The drive control circuit includes a solid relay, the positive input terminal of the solid relay is connected to a 3.3V voltage, the negative input terminal is connected to a control signal of a processor, the positive output terminal is connected to a 28V power supply, and the negative output terminal is connected to the IP+ terminal of the current sensor U5.

10. The intelligent three-phase contactor according to claim 1, characterized in that: The processor also communicates with the outside through a CAN transceiver.

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