Relay fault detection circuit and power distribution terminal controller
By designing a relay fault detection circuit that includes monitoring circuits for coil breakage and contact adhesion, and utilizing XOR gates and optocouplers, early identification of relay faults is achieved. This solves the problem that existing technologies cannot detect relay coil breakage, and improves safety and fault diagnosis efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHUHAI FEISEN POWER TECH CO LTD
- Filing Date
- 2026-03-26
- Publication Date
- 2026-05-01
AI Technical Summary
Existing relay fault detection circuits cannot effectively detect relay coil open circuits, leading to safety hazards.
Design a relay fault detection circuit, including a coil open circuit and a contact sticking detection circuit. The circuit uses an XOR gate and an optocoupler to detect relay coil open circuit and contact sticking faults, and achieves early fault identification through closing control signal and voltage detection.
It enables early identification of relay coil open circuits and contact sticking faults, avoiding safety accidents caused by relay failures and improving the troubleshooting efficiency of maintenance personnel.
Smart Images
Figure CN224190188U_ABST
Abstract
Description
A relay fault detection circuit and a power distribution terminal controller Technical Field
[0001] This utility model relates to the field of power equipment technology, specifically to a relay fault detection circuit and a power distribution terminal controller. Background Technology
[0002] The core function of a power distribution terminal is the control of power equipment, and the importance of relays as the control output of secondary equipment is self-evident. When equipment needs to be switched on or off in the field, "failure to operate" and "false operation" often occur due to relay failure, which can easily lead to safety accidents. To monitor relay faults, existing equipment uses relay fault detection circuits to detect whether a relay is faulty. However, existing relay fault detection circuits often only detect contact sticking faults and cannot detect relay coil open circuit faults. Therefore, a new relay fault detection scheme needs to be designed that can simultaneously detect faults in both the relay coil and the contacts. Summary of the Invention
[0003] In order to overcome the shortcomings of the existing technology, the purpose of this utility model is to provide a relay fault detection circuit and a power distribution terminal controller, which can detect relay coil open circuit and contact sticking faults, so as to facilitate maintenance personnel to troubleshoot relay faults in advance and avoid accidents.
[0004] To solve the above problems, the technical solution adopted by this utility model is as follows: A relay fault detection circuit includes a contact adhesion monitoring circuit and a coil breakage monitoring circuit. The coil breakage monitoring circuit includes a XOR gate and a first optocoupler. The first input terminal of the XOR gate is connected to a first voltage through the relay coil being detected. The first input terminal of the XOR gate is connected to the relay coil being detected through a resistor R12. The first input terminal of the XOR gate is also grounded through a pull-down resistor. The second input terminal of the XOR gate is connected to a closing control signal. The output terminal of the XOR gate outputs a coil fault signal. The positive terminal of the input of the first optocoupler is connected to the first voltage, and the negative terminal of the input of the first optocoupler is connected to the closing control signal. The two output terminals of the first optocoupler are respectively connected to the end of the relay coil being tested that is opposite to the first voltage and to ground. The contact adhesion monitoring circuit is a voltage detection feedback circuit. The two input terminals of the contact adhesion monitoring circuit are respectively connected to a pair of contacts of the relay being tested. The output terminal of the contact adhesion monitoring circuit outputs a high-level or low-level contact fault signal according to whether there is voltage between the pair of contacts of the relay being tested.
[0005] The relay fault detection circuit described above, the coil open circuit monitoring circuit further includes a second optocoupler. The positive terminal of the input of the second optocoupler is connected to the first voltage, the negative terminal of the input of the second optocoupler is connected to the output of the XOR gate, and the output of the second optocoupler is connected to the first voltage and ground respectively.
[0006] The relay fault detection circuit described above includes a contact adhesion monitoring circuit comprising a third optocoupler, a voltage base chip, and several resistors. Resistors R5 and R18 are connected in series, and the two ends of the series unit formed by resistors R5 and R18 are respectively connected to a pair of contacts of the relay being detected. The end of resistor R5 facing away from resistor R18 is connected to a second voltage, and the end of resistor R18 facing away from resistor R5 is grounded. The connection node between resistors R5 and R18 is connected to the reference terminal of the voltage base chip. The input terminal of the voltage base chip is grounded, and the output terminal of the voltage base chip is connected to the second voltage through resistors R7 and R8. The positive terminal of the input terminal of the third optocoupler is connected to the connection node between resistors R7 and R8, and the negative terminal of the input terminal of the third optocoupler is connected to the output terminal of the voltage base chip. The output terminal of the third optocoupler is connected to a first voltage and ground respectively.
[0007] The aforementioned relay fault detection circuit also includes an AND gate, the two input terminals of which are respectively connected to the output terminals of the coil disconnection monitoring circuit and the contact adhesion monitoring circuit, and the output terminal of the AND gate outputs a relay fault signal composed of the coil fault signal and the contact fault signal.
[0008] In the aforementioned relay fault detection circuit, the positive terminal of the input of the first optocoupler is connected to the first voltage through a resistor R1, the end of the resistor R1 facing away from the first optocoupler is connected to the negative terminal of the input of the first optocoupler through a resistor R2, and a capacitor C1 is provided between the two output terminals of the first optocoupler.
[0009] In the aforementioned relay fault detection circuit, the second input terminal of the XOR gate is connected to the closing control signal via resistor R14.
[0010] In the aforementioned relay fault detection circuit, the positive terminal of the input of the second optocoupler is connected to the first voltage through resistor R13, and one of the output terminals of the second optocoupler is connected to the first voltage through resistor R10.
[0011] In the aforementioned relay fault detection circuit, the first terminal of the output of the third optocoupler is connected to the first voltage through a resistor R21, and the second terminal of the output of the third optocoupler is grounded through a resistor R9.
[0012] A power distribution terminal controller includes the aforementioned relay fault detection circuit.
[0013] Compared to existing technologies, the advantages of this invention are as follows: This circuit and distribution terminal controller, by connecting the first input terminal of the XOR gate to the first voltage via the coil of the relay under test, and connecting the second input terminal of the XOR gate to the closing control signal, utilizes the characteristic that the sinking current of the XOR gate is much smaller than the driving current of the relay coil. This allows for the acquisition of the voltage at the "lower end" of the first coil during opening without driving the relay coil, thus enabling the detection of coil open-circuit faults. This circuit and distribution terminal controller facilitate timely troubleshooting by maintenance personnel to identify faults in the relays used to control opening and closing operations, preventing accidents caused by relay failures.
[0014] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0015] Figure 1 is a schematic diagram of the relay fault detection circuit according to an embodiment of the present invention. Detailed Implementation
[0016] The embodiments of this utility model are described in detail below. Referring to Figure 1, an embodiment of this utility model provides a relay fault detection circuit, including a coil open-circuit monitoring circuit and a contact adhesion monitoring circuit. The coil open-circuit monitoring circuit includes a multi-OR gate U5 and a first optocoupler U1. The first input terminal A of the multi-OR gate U5 is connected to a 5V first voltage through the relay coil being tested. The second input terminal B is connected to the relay coil being tested through a resistor R12. The first input terminal A of the multi-OR gate U5 is also grounded through a pull-down resistor R4. A low-level closing control signal representing closing is connected to the second input terminal B of the multi-OR gate U5. The output terminal of the multi-OR gate outputs a low-level coil fault signal representing an open-circuit fault in the relay coil of the tested relay. The positive terminal of the first optocoupler U1 is connected to the first voltage, the negative terminal is connected to the closing control signal, and the two output terminals are connected to the end of the relay coil being tested that is away from the first voltage and the ground of the first voltage, respectively. The contact adhesion monitoring circuit is a voltage detection feedback circuit. The two input terminals of the contact adhesion monitoring circuit are connected to a pair of contacts of the relay being tested, respectively. The output terminal of the contact adhesion monitoring circuit outputs a high-level or low-level contact fault signal according to whether there is voltage between the pair of contacts of the relay being tested.
[0017] In this relay fault detection circuit, when there is no closing operation command (i.e., the closing control signal is high), if the relay coil is normal, the 5V first voltage passes through the relay coil and the current-limiting resistor R12 to reach the first input terminal A of the XNOR gate U5, making the first input terminal A of the XNOR gate U5 also high. Since the closing control signal is also high at this time, the second input terminal B of the XNOR gate U5 is also high. According to the working characteristics of the XNOR gate, the output terminal of the XNOR gate U5 outputs a high level, which means that the relay coil of the relay under test has no open circuit fault. When the relay coil is burned out and broken, the 5V first voltage cannot reach the XNOR gate U5. The pull-down resistor R4 pulls the first input terminal A of the XNOR gate U5 down to a low level, thus making the two input terminals of the XNOR gate U5 inconsistent. The output terminal of the XNOR gate U5 outputs a low level, which means that the relay coil of the relay under test has an open circuit fault. Since the sink current of the XNOR gate U5 is only in the microamplitude range, it will not drive the relay coil to work. However, it can still present a high-level voltage through the current-limiting resistor R12, thus enabling the detection of the voltage of the relay coil under test in the open state, thereby realizing the detection of the relay coil's open circuit. When there is a closing operation command, that is, when the closing control signal is low, the first optocoupler U1 is turned on. If the relay coil is normal, the first voltage passes through the relay coil and directly to ground through the turned-on first optocoupler U1. At this time, the current flowing through the relay coil can drive the relay coil to work. At the same time, the first voltage cannot reach the first input terminal A of the XNOR gate U5. The first input terminal A of the XNOR gate U5 is pulled down to a low level by the pull-down resistor. The second input terminal B of the XNOR gate U5 is also at a low level at this time, thus making the output terminal of the XNOR gate U5 consistent with the voltage levels of the two input terminals. A high-level output signal indicates that the relay coil is fault-free. Although the voltage of the relay coil cannot be detected at this time, the output characteristics of the XOR gate U5 prevent the relay coil from being falsely detected as faulty due to the lack of voltage detection. If the relay coil is open-circuited, although the XOR gate U5 will still output a high-level signal indicating that the relay coil is fault-free because both inputs are low, the relay contacts cannot close due to the open circuit. Maintenance personnel can still detect the relay fault because no closing action is performed. When the contacts stick together, there is no potential difference between the contacts due to the short circuit. Therefore, a contact sticking monitoring circuit that detects the presence or absence of voltage between the contacts can be used to detect the contact sticking fault. This circuit can detect the open circuit fault of the relay coil in the open state and can determine whether the relay is sticking based on the presence or absence of voltage between the contacts. It can troubleshoot the relay fault before closing the circuit, thereby avoiding accidents caused by relay failure.
[0018] Referring to Figure 1, in this embodiment, the contact adhesion monitoring circuit is a voltage detection feedback circuit composed of a voltage base chip U7 and several resistors. The contact adhesion monitoring circuit also includes a third optocoupler U8. Specifically, resistors R5 and R18 in the contact adhesion monitoring circuit are connected in series. The two ends of the series unit formed by resistors R5 and R18 are respectively connected to a pair of contacts of the relay being detected. One end of resistor R5 facing away from resistor R18 is connected to a 24V second voltage, and one end of resistor R18 facing away from resistor R5 is connected to the ground of the second voltage. The connection node between resistors R5 and R18 is connected to the reference terminal R of the voltage base chip U7. The input terminal A of the voltage base chip U7 is grounded, and the output terminal K of the voltage base chip U7 is connected to the second voltage through resistors R7 and R8. The positive terminal of the input of the third optocoupler U8 is connected to the connection node between resistors R7 and R8, and the negative terminal of the input of the third optocoupler U8 is connected to the output terminal of the voltage base chip U7. The output terminal of the third optocoupler U8 is connected to the first voltage and the ground of the first voltage, respectively. This contact adhesion monitoring circuit, by appropriately setting the resistance values of resistors R5 and R18, ensures that when the contacts are normal, the voltage across resistor R18 is just enough to turn on the voltage base chip U7, thus turning on the third optocoupler U8. This allows pin 3 of the third optocoupler U8 to output a high-level contact fault signal, indicating that the contacts are not stuck. When the contacts are stuck, the voltage across resistor R18 is 0V, the voltage base chip U7 is turned off, and the third optocoupler U8 is turned off, causing pin 3 of the third optocoupler U8 to output a low-level contact fault signal, indicating that the contacts are stuck.
[0019] In this embodiment, referring to FIG1, the coil breakage monitoring circuit further includes a second optocoupler U6 to isolate the coil fault signal. The positive terminal of the input terminal of the second optocoupler U6 is connected to the first voltage, the negative terminal of the input terminal is connected to the output terminal of the XOR gate U5, and the output terminal is connected to the first voltage and the first voltage ground, respectively.
[0020] In this embodiment, referring to FIG1, in order to reduce the occupation of the I / O interface of the processor in the controller by the relay fault detection, the relay fault detection circuit also includes an AND gate U2. The first input terminal A of the AND gate U2 is connected to the end of the output terminal of the second optocoupler U6 that is connected to the first voltage, and the second input terminal B is connected to the ground end of the output terminal of the third optocoupler U8. The output terminal of the AND gate U2 is connected to the processor in the controller. When either the coil fault monitoring circuit or the contact sticking monitoring circuit outputs a low-level signal representing a fault, the AND gate U2 will feed back a low-level relay fault signal representing a relay fault to the processor, thereby feeding back the relay coil open wire or contact sticking fault to the processor through only one I / O interface.
[0021] Referring to Figure 1, in this embodiment, to protect the first optocoupler U1, the second optocoupler U6, the third optocoupler U8, the XOR gate U5, and the AND gate U2, and to ensure the stability of the closing control and prevent the closing action from being falsely triggered, the positive terminal of the input of the first optocoupler U1 is connected to the first voltage through a resistor R1, and the end of the resistor R1 facing away from the first optocoupler U1 is connected to the negative terminal of the input of the first optocoupler U1 through a resistor R2. A capacitor C1 is provided between the two output terminals of the first optocoupler U1. The second input terminal B of the XOR gate U5 is connected to the closing control signal through a resistor R14. The positive terminal of the input of the second optocoupler U6 is connected to the first voltage through a resistor R13, and one of its output terminals is connected to the first voltage through a resistor R10. The first output terminal of the third optocoupler U8 is connected to the first voltage through a resistor R21, and the second output terminal of the third optocoupler U8 is grounded through a resistor R9.
[0022] Based on the same inventive concept, embodiments of this utility model also provide a power distribution terminal controller, including at least one of the above-mentioned relay fault monitoring circuits, which can check for coil breakage and contact sticking faults in the relays in the controller before the closing operation, thereby ensuring the safety of the closing operation and avoiding accidents caused by relay faults.
[0023] It should be noted that in the description of this utility model, any descriptions of orientation, such as up, down, front, back, left, right, etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and should not be construed as a limitation of this utility model.
[0024] In the description of this utility model, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. If "first" or "second" is mentioned, it is only for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.
[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.
[0026] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.
Claims
1. A relay fault detection circuit, comprising a contact adhesion monitoring circuit, characterized in that, It also includes a coil breakage monitoring circuit, which comprises an XOR gate and a first optocoupler. The first input terminal of the XOR gate is connected to a first voltage through the relay coil being detected, and the first input terminal of the XOR gate is connected to the relay coil being detected through a resistor R12. The first input terminal of the XOR gate is also grounded through a pull-down resistor. The second input terminal of the XOR gate is connected to a closing control signal, and the output terminal of the XOR gate outputs a coil fault signal. The positive terminal of the first optocoupler's input terminal is connected to the first voltage, and the negative terminal of the first optocoupler's input terminal is connected to the closing control signal. The two output terminals of the first optocoupler are respectively connected to the end of the relay coil being detected that is away from the first voltage and to ground. The contact adhesion monitoring circuit is a voltage detection feedback circuit. The two input terminals of the contact adhesion monitoring circuit are respectively connected to a pair of contacts of the relay being detected. The output terminal of the contact adhesion monitoring circuit outputs a high-level or low-level contact fault signal based on whether there is voltage between the pair of contacts of the relay being detected.
2. The relay fault detection circuit according to claim 1, characterized in that, The coil breakage monitoring circuit further includes a second optocoupler. The positive terminal of the input of the second optocoupler is connected to the first voltage, the negative terminal of the input of the second optocoupler is connected to the output of the XOR gate, and the output of the second optocoupler is connected to the first voltage and ground, respectively.
3. The relay fault detection circuit according to claim 2, characterized in that, The contact adhesion monitoring circuit includes a third optocoupler, a voltage base chip, and several resistors. Resistors R5 and R18 are connected in series. The two ends of the series unit formed by resistors R5 and R18 are respectively connected to a pair of contacts of the relay being detected. The end of resistor R5 facing away from resistor R18 is connected to a second voltage, and the end of resistor R18 facing away from resistor R5 is grounded. The connection node between resistors R5 and R18 is connected to the reference terminal of the voltage base chip. The input terminal of the voltage base chip is grounded. The output terminal of the voltage base chip is connected to the second voltage through resistors R7 and R8. The positive terminal of the input terminal of the third optocoupler is connected to the connection node between resistors R7 and R8. The negative terminal of the input terminal of the third optocoupler is connected to the output terminal of the voltage base chip. The output terminal of the third optocoupler is connected to a first voltage and ground.
4. The relay fault detection circuit according to claim 3, characterized in that, It also includes an AND gate, whose two input terminals are respectively connected to the output terminals of the coil disconnection monitoring circuit and the contact adhesion monitoring circuit, and whose output terminal outputs a relay fault signal composed of the coil fault signal and the contact fault signal.
5. The relay fault detection circuit according to claim 1, characterized in that, The positive terminal of the input of the first optocoupler is connected to the first voltage through resistor R1, and the end of resistor R1 facing away from the first optocoupler is connected to the negative terminal of the input of the first optocoupler through resistor R2. A capacitor C1 is provided between the two output terminals of the first optocoupler.
6. The relay fault detection circuit according to claim 1, characterized in that, The second input terminal of the XOR gate is connected to the closing control signal via resistor R14.
7. The relay fault detection circuit according to claim 2, characterized in that, The positive terminal of the input of the second optocoupler is connected to the first voltage through resistor R13, and one of the output terminals of the second optocoupler is connected to the first voltage through resistor R10.
8. The relay fault detection circuit according to claim 3, characterized in that, The first terminal of the output of the third optocoupler is connected to the first voltage through resistor R21, and the second terminal of the output of the third optocoupler is grounded through resistor R9.
9. A power distribution terminal controller, characterized in that, Includes the relay fault detection circuit according to any one of claims 1 to 8.