An automatic transfer switch open-phase and under-voltage protection control circuit

Abstract

This utility model discloses an automatic transfer switch phase loss and undervoltage protection control circuit, belonging to the field of circuit protection technology. It includes an interconnected power supply circuit, a phase loss and undervoltage detection circuit, a relay control circuit, and a working status indicator circuit, forming a closed-loop control system. The power supply circuit provides operating voltage to the MCU and relays. The output of the phase loss and undervoltage detection circuit is connected to the input of the MCU, transmitting the detected three-phase voltage change signal to the MCU. The output of the MCU is connected to the relay control circuit, controlling the relay's engagement and disengagement based on the detection signal. The working status indicator circuit is connected to the MCU, receiving the MCU's control signal and displaying the circuit's working status. This utility model, through the collaborative design of three-phase independent detection circuits and MCU intelligent control, achieves rapid and accurate identification of phase loss and undervoltage faults and automatically switches to backup power. The innovative LED status indicator design makes fault diagnosis more intuitive and significantly improves operation and maintenance efficiency.

Description

Technical Field

[0001] This utility model relates to the field of circuit protection technology, and in particular to an automatic transfer switch phase loss and undervoltage protection control circuit. Background Technology

[0002] Three-phase motors are widely used as power equipment in industrial production and power systems. However, in actual operation, three-phase power supplies often experience faults such as phase loss or undervoltage. If these faults are not detected and dealt with in time, they will lead to motor overheating, reduced efficiency, or even burnout, causing serious economic losses.

[0003] Traditional protection devices often use mechanical relays or simple electronic circuits to achieve protection functions, which suffer from slow response speed, low accuracy, and poor reliability. In addition, existing protection circuits often lack intuitive status indication functions, making it difficult for maintenance personnel to quickly determine the type of fault. To address these issues, we have introduced an automatic transfer switch phase loss and undervoltage protection control circuit. Utility Model Content

[0004] This utility model discloses an automatic transfer switch phase loss and undervoltage protection control circuit, which aims to solve the technical problems of slow response speed, poor reliability and lack of status indication in three-phase motor protection circuits.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An automatic transfer switch phase loss and undervoltage protection control circuit includes an interconnected power supply circuit, a phase loss and undervoltage detection circuit, a relay control circuit, and a working status indication circuit, forming a closed-loop control system. The power supply circuit provides operating voltage to the MCU and the relay. The output terminal of the phase loss and undervoltage detection circuit is connected to the input terminal of the MCU to transmit the detected three-phase voltage change signal to the MCU. The output terminal of the MCU is connected to the relay control circuit to control the activation and deactivation of the relay according to the detection signal. The working status indication circuit is connected to the MCU to receive the control signal from the MCU and display the circuit's working status.

[0006] The overall solution enables intelligent monitoring and automatic switching of three-phase power supply, solving the problems of slow response and poor reliability of traditional protection devices.

[0007] In a preferred embodiment, the power supply circuit includes resistors R19, R18, R16, and R17, capacitors C7, C8, C9, C6, C4, and C2, and diodes D7, D6, and D4, which are connected to provide a stable operating voltage for the MCU and the relay.

[0008] The optimized power supply circuit design ensures that the MCU and relays can operate stably under various conditions, improving system reliability.

[0009] In a preferred embodiment, the phase loss and undervoltage detection circuit includes an A-phase detection circuit, a B-phase detection circuit, and a C-phase detection circuit. The A-phase detection circuit consists of diode D1, resistors R1, R2, R3, R4, and capacitor C1; the B-phase detection circuit consists of diode D2, resistors R5, R6, R7, R8, and capacitor C3; and the C-phase detection circuit consists of diode D3, resistors R9, R10, R11, R12, and capacitor C5. Each phase detection circuit is used to detect the voltage change of the corresponding phase and input the detection signal to the MCU.

[0010] The three-phase independent detection circuit can accurately identify faults in each phase, avoid misjudgment and missed judgment, and improve the detection accuracy significantly compared with traditional solutions.

[0011] In a preferred embodiment, the relay control circuit includes an MCUU1, resistors R14 and R15, transistor Q1, diode D5, and relay K1. The MCUU1 controls the conduction and cutoff of transistor Q1 according to the signal from the phase loss and undervoltage detection circuit, thereby controlling the engagement and disengagement of relay K1.

[0012] The relay is controlled by an MCU, which shortens the response time and makes it several times faster than mechanical relays.

[0013] In a preferred embodiment, the operating status indication circuit includes MCUU1, resistor R13 and indicator LED1. When the three-phase voltage is normal, LED1 flashes; when the three-phase voltage is interrupted or undervoltage occurs, LED1 remains constantly lit.

[0014] The innovative status indicator design makes fault identification more intuitive and significantly improves operation and maintenance efficiency.

[0015] In a preferred embodiment, the relay K1 is used to control the power supply switching of the motor. When the three-phase voltage is normal, the relay K1 is energized and the motor is connected to the normal power supply. When the three-phase voltage is abnormal, the relay K1 is de-energized and the motor is connected to the backup power supply.

[0016] A reliable power switching mechanism ensures that the motor seamlessly switches to the backup power supply in the event of a power failure, preventing equipment damage.

[0017] The automatic transfer switch phase loss and undervoltage protection control circuit provided by this utility model has the following advantages: Firstly, this invention achieves rapid and accurate identification of phase loss and undervoltage faults through the collaborative design of a three-phase independent detection circuit and MCU intelligent control, and automatically switches to backup power. The innovative LED status indicator design makes fault diagnosis more intuitive and significantly improves operation and maintenance efficiency. The overall circuit structure is simple and reliable, with significantly improved detection accuracy and response speed compared to traditional solutions. It effectively prevents motor damage due to power failures, extends equipment lifespan, and has significant economic and safety benefits.

[0018] Secondly, the use of MCU intelligent control relays significantly reduces response time, making them several times faster than mechanical relays. Innovative status indicator design makes fault identification more intuitive, greatly improving operational efficiency. A reliable power switching mechanism ensures seamless switching of the motor to backup power in the event of a power failure, preventing equipment damage. Attached Figure Description

[0019] Figure 1 This is a circuit diagram of an automatic transfer switch phase loss and undervoltage protection control circuit proposed in this utility model. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and marked in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] In what scenarios is the automatic transfer switch phase loss and undervoltage protection control circuit disclosed in this utility model mainly applied?

[0022] Reference Figure 1An automatic transfer switch phase loss and undervoltage protection control circuit includes an interconnected power supply circuit, a phase loss and undervoltage detection circuit, a relay control circuit, and a working status indication circuit, forming a closed-loop control system. The power supply circuit provides operating voltage to the MCU and the relay. The output of the phase loss and undervoltage detection circuit is connected to the input of the MCU to transmit the detected three-phase voltage change signal to the MCU. The output of the MCU is connected to the relay control circuit to control the activation and deactivation of the relay based on the detection signal. The working status indication circuit is connected to the MCU to receive the control signal from the MCU and display the circuit's operating status. The power supply circuit includes resistors R19, R18, R16, and R17, capacitors C7, C8, C9, C6, C4, and C2, and diodes D7, D6, and D4, which, through their connection, provide a stable operating voltage to the MCU and the relay. The phase loss and undervoltage detection circuit includes an A-phase detection circuit, a B-phase detection circuit, and a C-phase detection circuit. The A-phase detection circuit consists of diode D1, resistors R1, R2, R3, R4, and capacitor C1. The B-phase detection circuit consists of diode D2, resistors R5, R6, R7, R8, and capacitor C3. The C-phase detection circuit consists of diode D3, resistors R9, R10, R11, R12, and capacitor C5. Each phase detection circuit is used to detect the voltage change of the corresponding phase and input the detection signal to the MCU.

[0023] In this embodiment, the power supply circuit provides a stable DC operating voltage to the MCU and relays after voltage reduction, rectification, filtering, and regulation. The three-phase independent phase loss and undervoltage detection circuit (phases A / B / C are composed of D1-R1-R4-C1, D2-R5-R8-C3, and D3-R9-R12-C5 respectively) collects the voltage signals of each phase in real time. The signals are then converted from analog to digital and compared with thresholds via the MCU's AD conversion interface. When the three-phase voltage is normal, the MCU controls the relay K1 to engage, connecting the motor to the main power supply. At the same time, it drives LED1 to flash at a frequency of 1Hz to indicate the normal status. When any phase undervoltage or phase loss is detected, the MCU releases K1 within 20ms to switch to the backup power supply and issues an alarm signal by keeping LED1 constantly lit. The diode D5 in the relay control circuit can effectively absorb the reverse electromotive force to protect the switching transistor Q1, thereby achieving fast and reliable three-phase power supply protection and status indication.

[0024] In the above technical solution, considering the problems of slow response speed, poor reliability, and lack of status indication in the three-phase motor protection circuit, the specific operation is as follows to solve these problems: Reference Figure 1In a preferred embodiment, the relay control circuit includes an MCUU1, resistors R14 and R15, transistor Q1, diode D5, and relay K1. The MCUU1 controls the conduction and cutoff of transistor Q1 based on the signal from the phase loss and undervoltage detection circuit, thereby controlling the engagement and disengagement of relay K1. The operating status indication circuit includes an MCUU1, resistor R13, and indicator LED1. LED1 flashes when the three-phase voltage is normal and remains lit when there is a phase loss or undervoltage. Relay K1 controls the power switching of the motor. When the three-phase voltage is normal, relay K1 engages, and the motor is connected to the mains power supply. When the three-phase voltage is abnormal, relay K1 disengages, and the motor is connected to the backup power supply.

[0025] This embodiment utilizes an MCU intelligent control relay, resulting in a significantly shorter response time—several times faster than mechanical relays. An innovative status indicator design makes fault identification more intuitive, greatly improving operational efficiency. A reliable power switching mechanism ensures seamless switching of the motor to backup power in the event of a power failure, preventing equipment damage.

[0026] Working principle: The power supply circuit provides a stable DC operating voltage to the MCU and relays after voltage reduction, rectification, filtering and stabilization through RC step-down, rectification and filtering. The three-phase independent phase loss and undervoltage detection circuit (A / B / C phases are composed of D1-R1-R4-C1, D2-R5-R8-C3, and D3-R9-R12-C5 respectively) collects the voltage signal of each phase in real time. The signal is converted from analog to digital and compared with the threshold through the MCU's AD conversion interface. When the three-phase voltage is normal, the MCU controls the relay K1 to close so that the motor is connected to the normal power supply. At the same time, the LED1 is driven to flash at a frequency of 1Hz to indicate the normal status. When any phase undervoltage (below 85% of the rated voltage) or phase loss is detected, the MCU releases K1 within 20ms to switch to the backup power supply and issues an alarm signal by keeping the LED1 constantly lit. The diode D5 in the relay control circuit can effectively absorb the reverse electromotive force to protect the switching transistor Q1, thereby realizing fast and reliable three-phase power supply protection and status indication.

[0027] The above description is merely a preferred embodiment of this utility model, but the protection scope of this utility model is not limited thereto. The substitutions may be replacements of some structures, devices, or method steps, or they may be complete technical solutions. Equivalent substitutions or modifications made based on the technical solution and inventive concept of this utility model should all be covered within the protection scope of this utility model.

Claims

1. An automatic transfer switch phase loss and undervoltage protection control circuit, comprising an interconnected power supply circuit, a phase loss and undervoltage detection circuit, a relay control circuit, and a working status indication circuit, forming a closed-loop control system, characterized in that: The power supply circuit provides operating voltage for the MCU and relays. The output of the phase loss and undervoltage detection circuit is connected to the input of the MCU to transmit the detected three-phase voltage change signal to the MCU. The output of the MCU is connected to the relay control circuit to control the relay to engage and disengage according to the detection signal. The operating status indicator circuit is connected to the MCU to receive the control signal from the MCU and display the circuit operating status.

2. An automatic transfer switch open phase and under voltage protection control circuit according to claim 1, characterized in that: The power supply circuit includes resistors R19, R18, R16, and R17, capacitors C7, C8, C9, C6, C4, and C2, and diodes D7, D6, and D4, which are connected to provide a stable operating voltage for the MCU and the relay.

3. An automatic transfer switch open phase and under voltage protection control circuit according to claim 1, characterized in that: The phase loss and undervoltage detection circuit includes an A-phase detection circuit, a B-phase detection circuit, and a C-phase detection circuit. The A-phase detection circuit consists of diode D1, resistors R1, R2, R3, R4, and capacitor C1. The B-phase detection circuit consists of diode D2, resistors R5, R6, R7, R8, and capacitor C3. The C-phase detection circuit consists of diode D3, resistors R9, R10, R11, R12, and capacitor C5. Each phase detection circuit is used to detect the voltage change of the corresponding phase and input the detection signal to the MCU.

4. An automatic transfer switch open phase and under voltage protection control circuit according to claim 1, characterized in that: The relay control circuit includes MCUU1, resistors R14 and R15, transistor Q1, diode D5, and relay K1. MCUU1 controls the conduction and cutoff of transistor Q1 according to the signal from the phase loss and undervoltage detection circuit, thereby controlling the engagement and disengagement of relay K1.

5. An automatic transfer switch open phase and under voltage protection control circuit according to claim 1, characterized in that: The operating status indicator circuit includes MCUU1, resistor R13 and indicator LED1. When the three-phase voltage is normal, LED1 flashes. When the three-phase voltage is interrupted or undervoltage occurs, LED1 remains lit.

6. The automatic transfer switch phase loss and undervoltage protection control circuit according to claim 1, characterized in that: The relay K1 is used to control the power supply switching of the motor. When the three-phase voltage is normal, the relay K1 is energized and the motor is connected to the normal power supply. When the three-phase voltage is abnormal, the relay K1 is deactivated and the motor is connected to the backup power supply.

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