A detection method based on an online monitoring device for relays used in rail transit vehicles

Abstract

This invention relates to the field of rail transit vehicle technology, and more particularly to a detection method based on an online monitoring device for relays used in rail transit vehicles. The online monitoring device for relays includes a motherboard, a main control board plugged into the motherboard, and at least one detection board. The method includes the following steps: the detection board detects the state of the relay coil and contacts, the relay coil resistance, and / or the relay contact resistance, and sends the detection results to the main control board; the main control board receives the detection results from the detection board and sends control data and / or fault diagnosis data based on the detection results. This invention allows for the diagnosis and recording of relay operating status, fault analysis, and lifespan management, and enables online downloading and uploading, thus improving the intelligent operation and maintenance system for trains. Online relay monitoring can improve the overall reliability of control circuits, ensure stable train operation, reduce maintenance costs, and improve maintenance efficiency.

Description

Technical Field

[0001] This invention relates to the field of rail transit vehicle technology, and in particular to a detection method based on an online monitoring device for relays used in rail transit vehicles. Background Technology

[0002] Relays play a crucial role in the control of rail transit vehicles, with each train containing up to 200 or more relays. These relays are responsible for signal transmission and various logic controls, such as train activation, driver's cab occupancy, door status detection, pantograph raising and lowering control, and traction and braking circuit control. Therefore, the state of the relays directly affects train operation. Statistical analysis of train control circuit faults shows that over 60% of these faults are caused by relay malfunctions.

[0003] The main causes of relay failure are as follows: 1. Relays are heat-sensitive components. High temperatures accelerate the aging of the relay insulation material and the oxidation and corrosion of the contacts, causing changes in electrical parameters. 2. As the coil resistance increases with temperature and the coil power decreases, the relay's operating voltage will increase under high-temperature conditions, while the release voltage will decrease under low-temperature conditions, affecting the relay's normal switching. 3. Low temperatures also exacerbate contact adhesion, cause condensation on the contact surface, and create a cold film on the armature surface, preventing the contacts from functioning properly. 4. Relays exposed to dust and moisture for extended periods experience a decrease in insulation strength. Under overvoltage during inductive load switching, this can lead to insulation breakdown failure. 5. When relays handle low loads, insufficient wetting current cannot effectively remove the surface oxide film, resulting in poor contact. 6. When relays handle high loads, even if the excessive load does not exceed the rated current, the surge current caused by the load difference at the moment of contact can easily cause the contacts to melt, wear out, or shift.

[0004] These unfavorable conditions directly affect the reliability and lifespan of relays. Currently, there is no tracking and monitoring of relay status on rail transit vehicles, resulting in blind spots in relay monitoring. The maintenance and replacement of relays relies on experience, with replacements occurring every 5-7 years, which has numerous drawbacks.

[0005] Therefore, there is room for improvement in existing technologies. Summary of the Invention

[0006] This application summarizes various aspects of the embodiments and should not be construed as limiting the claims. Other implementations are contemplated based on the technology described herein, as will be apparent to those skilled in the art upon studying the following drawings and detailed descriptions, and these implementations are intended to be included within the scope of this application.

[0007] To address this problem, the present invention proposes a solution for online relay monitoring.

[0008] Specifically, the present invention provides a detection method based on an online monitoring device for relays used in rail transit vehicles. The online monitoring device for relays used in rail transit vehicles includes: a motherboard, a main control board plugged into the motherboard, and at least one detection board. The detection method includes the following steps: the detection board detects the state of the relay coil and contacts, the relay coil resistance, and / or the relay contact resistance, and sends the detection results to the main control board; and the main control board receives the detection results from the detection board and sends control data and / or fault diagnosis data based on the detection results.

[0009] According to an embodiment of the present invention, the detection board includes one of a voltage state detection board, a contact detection board, and a coil detection board, and each of the voltage state detection board, the contact detection board, and the coil detection board includes a corresponding detection circuit.

[0010] According to an embodiment of the present invention, the detection circuit of the voltage state detection board includes an optocoupler, and the detection method includes: real-time monitoring of the relay coil and contact level signals through the optocoupler, and determining whether the relay coil and contact state is normal based on the transition of the relay coil and contact level signals; and detecting the operating time of the relay contact based on the time difference of the transition of the relay coil and contact level signals.

[0011] According to an embodiment of the present invention, the detection method includes: comparing the operating time with the rated operating time of the relay contact; predicting the abnormal trend of the relay based on the comparison result; and providing a manual inspection or repair / replacement prompt based on the abnormal trend.

[0012] According to an embodiment of the present invention, the detection circuit of the coil detection board includes mechanical contacts and a semiconductor high-resistance isolation device, and the detection method includes: applying a constant current source excitation to the detection circuit of the coil detection board in response to a transition of the coil input level signal from low level to high level and the closure of the mechanical contacts, and calculating the resistance value of the coil based on the excitation voltage across the coil; and removing the constant current source excitation from the detection circuit of the coil detection board in response to a transition of the coil input level signal from high level to low level and the opening of the mechanical contacts, thereby maintaining electrical isolation between the detection circuit of the coil detection board and the circuit of the rail transit vehicle.

[0013] According to an embodiment of the present invention, the detection circuit of the contact detection board includes mechanical contacts and a semiconductor high-resistance isolation device, and the detection method includes: applying a constant current source excitation to the detection circuit of the contact detection board in response to a transition of the contact input level signal from low level to high level and the closure of the mechanical contacts, and calculating the resistance value of the contacts based on the excitation voltage across the contacts; and removing the constant current source excitation from the detection circuit of the contact detection board in response to a transition of the contact input level signal from high level to low level and the closure of the mechanical contacts, thereby maintaining electrical isolation between the detection circuit of the contact detection board and the circuit of the rail transit vehicle.

[0014] According to an embodiment of the present invention, the detection method includes providing the constant current source excitation through a floating isolated power supply, wherein the floating isolated power supply is completely isolated from the power supply of the rail transit vehicle.

[0015] According to an embodiment of the present invention, the detection method includes: comparing the resistance value of the coil with the rated resistance value of the relay coil, or comparing the resistance value of the contact with the rated resistance value of the relay contact; predicting the abnormal trend of the relay based on the comparison result; and providing a manual inspection or repair / replacement prompt based on the abnormal trend.

[0016] According to an embodiment of the present invention, the detection method includes: determining whether the relay and the rail transit vehicle circuit are faulty based on the detection result; generating the fault diagnosis data based on the determination result; sending the detection result and / or the fault diagnosis data to a server for full life-cycle monitoring and management of the relay; and / or issuing an alarm based on the detection result and / or the fault diagnosis data.

[0017] According to an embodiment of the present invention, the detection method includes: establishing a life model of the relay based on the relay's technical parameters, life curve, and load type; and correcting the relay's life model based on the detection results.

[0018] The detection method based on the online monitoring device for relays in rail transit vehicles provided by this invention can diagnose and record the relay's operating status, fault analysis, and lifespan management, and can download and upload data online. This improves the intelligent operation and maintenance system of trains, fills the gap in online relay monitoring technology, and has significant practical value. Online relay monitoring can improve the overall reliability of control circuits, ensure stable train operation, reduce maintenance costs, and improve maintenance efficiency, fundamentally solving the problem of relay troubleshooting and detection.

[0019] Upon studying the following description, claims and drawings, those skilled in the art will understand and recognize these and other aspects, objects and features of this disclosure. Attached Figure Description

[0020] To gain a more complete understanding of the embodiments of this application, reference should be made to the embodiments described in more detail in the accompanying drawings and by way of example below, wherein:

[0021] Figure 1 A schematic diagram of the electromagnetic relay is shown.

[0022] Figure 2 A schematic diagram of the architecture of an online monitoring device for relays in rail transit vehicles according to an embodiment of the present invention is shown;

[0023] Figure 3 A schematic diagram of the structure of an online monitoring device for relays in rail transit vehicles according to an embodiment of the present invention is shown;

[0024] Figure 4 A flowchart of a detection method based on an online monitoring device for relays used in rail transit vehicles according to an embodiment of the present invention is shown;

[0025] Figure 5 A circuit diagram of a voltage state detection board according to an embodiment of the present invention is shown;

[0026] Figure 6 A circuit diagram of a coil detection board according to an embodiment of the present invention is shown;

[0027] Figure 7 A circuit diagram of a contact detection board according to an embodiment of the present invention is shown;

[0028] Figure 8 A network topology diagram of an online monitoring device for relays in rail transit vehicles according to an embodiment of the present invention is shown;

[0029] Figure 9 A schematic diagram illustrating a circuit fault detection method using an online monitoring device for relays in rail transit vehicles according to an embodiment of the present invention is shown; and

[0030] Figure 10 A schematic diagram illustrating relay abnormality trend judgment and life-cycle management according to an embodiment of the present invention is shown. Detailed Implementation

[0031] The following describes embodiments of the present disclosure. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various alternative forms. The drawings are not necessarily drawn to scale; certain functions may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to use the application in various ways. As those skilled in the art will understand, various features shown and described with reference to any of the drawings may be combined with features shown in one or more other drawings to produce embodiments not explicitly shown or described. The combinations of features shown provide representative embodiments for typical applications. However, various combinations and modifications of features consistent with the teachings of this disclosure may be desirable for certain particular applications or implementations.

[0032] Furthermore, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or action from another, and do not necessarily require or imply any actual such relationship or order between these entities or actions. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements may include not only those elements but also elements not expressly listed or inherent to such processes, methods, articles, or apparatuses.

[0033] The following describes one or more embodiments of this application with reference to the accompanying drawings. The flowcharts illustrate the processes performed by the system according to this application. It is understood that the execution of the flowcharts does not need to be sequential; one or more steps may be omitted, one or more steps may be added, and steps may be performed in a sequential or reverse order. In some embodiments, one or more steps may even be performed simultaneously.

[0034] A relay is an actuator that uses electromagnetic principles to close or open contacts to control a circuit. It is essentially an automatic switch that uses low voltage and small current to control high current and high voltage, and it is widely used in automatic control systems, measurement and control systems, and relay protection systems.

[0035] like Figure 1 As shown, a relay generally consists of an iron core 2, a coil 1, an armature 7, contacts 9 and 10, an adjusting nut 5, an adjusting screw 6, and a non-magnetic washer 8. The working principle is that when the coil 1 is energized, a certain current flows through the coil 1, generating magnetic flux in the magnetic circuit composed of the yoke 3, the iron core 2, the armature 7, and the air gap, thereby producing an electromagnetic effect. This causes the movable armature 7 to be attracted to the iron core 2. The movement of the armature 7 drives the push rod to push the spring 4 to move, thereby causing the moving contact 9 of the armature 7 to engage with the stationary contact 10.

[0036] Because relays are mechatronic electrical devices, most of them maintain a stable state under mechanical elasticity. However, under electromagnetic force or other environmental influences, they transform into another state, altering electrical connections or fluid paths. Mechanical elastic forces inevitably experience jamming and adhesion, gradually reducing their force and causing contacts to fail to operate. While electrical contacts can meet the requirements of short-circuiting and disconnecting circuits under external control, their exposure to air and frequent switching conditions lead to dust accumulation, oxidation, and wear, resulting in increased contact resistance and even open circuits. Random faults occurring in relays under operating conditions may appear normal under non-operating conditions, making effective fault location and handling impossible. Currently, a significant amount of manpower is required for regular disassembly and inspection of relays. However, pressing the switch during manual inspection does not equate to it being engaged during vehicle operation. Random faults occurring under vehicle operating conditions do not exist under non-vehicle operating conditions. Due to the lack of operational characteristics of relays under various conditions, there is no reliable method for predicting the lifespan of relays, leading to the premature replacement of some normally functioning relays. The table below shows the failure modes and causes of various internal components of the relays:

[0037]

[0038]

[0039] In summary, existing technologies have at least the following problems:

[0040] 1) The operating status of the relays cannot be monitored, and there are no alarm prompts or emergency handling suggestions when a fault occurs, which affects the stability of train operation.

[0041] 2) The coil and contact resistance of the relay cannot be monitored, and it does not have a lifespan prediction function, so it is impossible to achieve full life cycle management of the relay.

[0042] 3) The relay's historical operating data cannot be automatically recorded, and it lacks data analysis capabilities, making it impossible to provide preventative maintenance suggestions.

[0043] 4) The repair and replacement of relays are carried out based on experience, and are only carried out every 5 to 7 years, which results in a waste of manpower and materials, low inspection efficiency and high maintenance costs.

[0044] To address the problems existing in current technologies, this invention proposes a detection method based on an online monitoring device for relays used in rail transit vehicles. The online monitoring device (RMU) is an intelligent operation and maintenance device installed on rail transit vehicles, consisting of multiple circuit boards, for online monitoring of relays. On the one hand, it can monitor the relay status in real time, locate relay faults, and track relay lifespan; on the other hand, it can deeply analyze relay operating data, promptly detect abnormal trends in relays, and formulate maintenance plans in advance, achieving fault prediction and anticipation. It includes methods for detecting relay operating status, coil resistance, and contact resistance. This device can simultaneously perform at least the following functions:

[0045] ● Real-time monitoring of relay operating status and data;

[0046] ●Accurately determine the fault status and cause of the relay;

[0047] ●Analyze and predict abnormal trends and lifespan of relays;

[0048] ● Data analysis, alarm, storage, download and upload functions;

[0049] ●Self-diagnosis and redundancy isolation functions;

[0050] ● Import function for technical parameters and lifespan curves;

[0051] ● Vehicle circuit analysis function;

[0052] ● The detection module is flexibly configurable and can be expanded.

[0053] ●Multi-standard communication functions.

[0054] When the relay-based online monitoring device of a rail transit vehicle diagnoses a fault in the device itself, it immediately stops monitoring, isolates the fault, and will not cause any adverse effects on the vehicle control circuit.

[0055] like Figure 2 and Figure 3 As shown, the online monitoring device for relays in rail transit vehicles may include: a motherboard, a main control board plugged into the motherboard, and at least one detection board. Furthermore, the online monitoring device for relays in rail transit vehicles may also include a power supply board, a communication board, and a display board, also plugged into the motherboard. These boards (or cards) communicate with each other via a CAN bus, and the number of boards can be expanded according to different project requirements. Among them:

[0056] The power board is responsible for providing the device with the necessary internal operating power.

[0057] The communication board is responsible for communicating with rail transit vehicle buses (MVB, TRDP, etc.) or 4G, 5G modules, etc.

[0058] The main control board can be a microprocessor or a microcontroller unit (MCU). It is responsible for receiving data from each board and performing calculations, sending control data and periodically diagnosing faults; recording system operation data and board status; communicating with data analysis and monitoring software; uploading recorded data; and downloading configuration data.

[0059] The display board is responsible for showing the operating status of each detection board and can perform vehicle-level equipment cascading.

[0060] The detection board is responsible for collecting the relay's operating data (which can be flexibly configured as follows):

[0061] Voltage Status Detection Board (VSD): 46-channel control voltage status input detection;

[0062] Contact detection board (CON): 24-channel contact voltage status and contact resistance detection;

[0063] Coil Detection Board (COI): 36-channel coil voltage status and resistance detection.

[0064] The motherboard serves as the medium for interconnecting the functions of all the individual boards. All individual boards are plugged into the motherboard as plug-ins. The motherboard provides each board with power interfaces, communication bus interfaces, communication address setting interfaces, and other features.

[0065] In embodiments of the present invention, the power board can also be referred to as a power module, the main control board can also be referred to as a control and computing module, the communication board can also be referred to as a communication module, the display board can also be referred to as a cascaded display module, and the detection board can also be referred to as a detection module.

[0066] like Figure 4 As shown, the detection method may include the following steps:

[0067] S101. The detection board detects the status of the relay coil and contacts, the relay coil resistance, and / or the relay contact resistance, and sends the detection results to the main control board; and

[0068] S103. The main control board receives the detection results from the detection board and sends control data and / or fault diagnosis data based on the detection results.

[0069] The detection board may include one of a voltage state detection board, a contact detection board, and a coil detection board, and each of the voltage state detection board, contact detection board, and coil detection board includes a corresponding detection circuit. In embodiments of the present invention, the detection circuit of the voltage state detection board can detect the state of the relay coil and contacts, the detection circuit of the contact detection board can detect the resistance of the relay coil, and the detection circuit of the coil detection board can detect the resistance of the relay contacts. A detailed description follows:

[0070] Relay coil and contact status detection

[0071] The relay coil and contact status detection relies on the voltage measurement circuit of the detection module to detect the gain / loss of voltage in each coil and the on / off state of the contacts. The detection method uses an input level signal comparison design; by recording the transitions in the voltage signal at the positive terminal of the sampling coil or contact, the status of the sampling coil or contact is analyzed. The detection circuit adopts an optocoupler isolation design; in failure modes, it is always open-circuited and will not affect the relay or circuit under test.

[0072] like Figure 5 As shown, the input level signals of the relay coil and contacts are connected to the primary side of the optocoupler to form a signal input circuit, and the microprocessor's I / O lines are connected to the secondary side of the optocoupler to form a signal acquisition circuit, thereby realizing real-time monitoring of the relay coil and contact level signals. The input current for level signal detection is less than 1mA, featuring low power consumption and high-reliability isolation, and is reliably isolated through the optocoupler. Input voltage range: low level DC 0~30V, high level DC 77~137.5V.

[0073] When the coil is energized and the contacts are closed, the input level signal is high. The energization of the coil and the closing of the contacts are detected by the transitions of the input level signals VSD1+, VSD2+, and VSD3+ from low to high. Finally, the contact closing time is detected by calculating the time difference of the VSD3+ level transition.

[0074] When the coil is de-energized or the contacts open, the input level signal is low. The de-energization of the coil and the release of the contacts are detected by the transition of the input level signal from high to low at VSD2+ and VSD3+. Finally, the release time of the contacts is detected by calculating the time difference of the transition of the level signal VSD3+.

[0075] Relay coil resistance detection

[0076] The coil resistance detection relies on the resistance measurement circuit of the detection module and uses an isolated signal generation circuit to calculate the coil resistance. The detection method employs a constant current source excitation design, calculating the resistance value of the sampling resistor by measuring the voltage change of the sampling resistor. The detection circuit uses a mechanical contact plus semiconductor high-resistance redundant isolation design, allowing for self-detection of any fault and immediate disconnection of the detection circuit, completely isolating it from the relay or circuit under test.

[0077] like Figure 6 As shown, the coil resistance detection uses a floating isolated power supply, which is completely isolated from the vehicle power supply. The isolation design uses two redundant isolation methods: mechanical contacts and semiconductor high resistance. Faults at any point can be detected by self-testing, avoiding any impact on the vehicle circuit.

[0078] When the coil is energized, the input level signal is high. Based on the transition of the input level signal COI1+ from low to high, the microprocessor drives the mechanical contacts to close and provides constant current source excitation to the coil detection circuit. Finally, the detection circuit identifies the magnitude of the excitation voltage from the two ends of the coil, COI1+ and COI1-, and calculates and detects the resistance of the coil.

[0079] When the coil is de-energized, the input signal level is low. Based on the transition of the input signal COI1+ from high to low, the microprocessor drives the mechanical contacts to open and removes the constant current source excitation from the coil detection circuit, ensuring effective electrical isolation between the detection circuit and the vehicle circuit.

[0080] Relay contact resistance detection

[0081] Contact resistance detection relies on the resistance measurement circuit of the detection module, using an isolated signal generation circuit to calculate the contact resistance value. The detection method also employs a constant current source excitation design, calculating the resistance value of the sampling resistor by measuring the voltage change. The detection circuit still uses a mechanical contact plus semiconductor high-resistance redundant isolation design; any fault at any point can be detected through self-testing, immediately disconnecting the detection circuit and completely isolating it from the relay or circuit under test.

[0082] like Figure 7 As shown, the contact resistance detection uses a floating isolated power supply, which is completely isolated from the vehicle power supply. The isolation design uses both mechanical contacts and semiconductor high-resistance redundant isolation. Faults at any point can be detected by self-testing, avoiding any impact on the vehicle circuit.

[0083] When the contacts are closed, the input signal is high. Based on the transition of the input signal CON2+ from low to high, the microprocessor drives the mechanical contacts to close and provides constant current excitation to the contact detection circuit. Finally, the detection circuit identifies the magnitude of the excitation voltage from CON1+ and CON2+ at both ends of the contacts and calculates and detects the resistance of the contacts.

[0084] When the contacts are open, the input signal is low. Based on the transition of the input signal CON2+ from high to low, the microprocessor drives the mechanical contacts to open and removes the constant current source excitation from the contact detection circuit, ensuring effective electrical isolation between the detection circuit and the vehicle circuit.

[0085] Therefore, the detection method based on the online monitoring device for relays in rail transit vehicles described in this invention can at least obtain information or detection results such as relay coil status, contact status, pull-in time, release time, coil resistance, and contact resistance. In embodiments of this invention, the testing method can also process and store the obtained information or detection results, and simultaneously upload the data to a server via a network. This data can then be monitored and managed by a ground-based expert system, thereby achieving full-lifecycle monitoring and management of the relay. Figure 8 As shown.

[0086] In embodiments of the present invention, the detection method based on the online monitoring device for relays used in rail transit vehicles can also achieve relay and circuit fault detection:

[0087] Faulty relays and circuits can be identified by analyzing data such as the voltage input to the relay coil, the voltage input to the contacts, and the consistency of contact operation states. Specifically, this can be combined with... Figure 9 The explanation is as follows:

[0088] When car 1 (Tc1) is activated, relay 21-K05 is energized, and contacts B1 and C1 of car 1 are engaged. Simultaneously, relay 21-K05 of car 6 remains de-energized, and contacts B1 and A1 of car 6 remain closed. At this time, if the online monitoring device detects that the input level signal VSD2+ of relay 21-K05 of car 6 and the input level signal VSD3+ of contacts B1 and A1 are low, it determines that the circuit is abnormal and that relay 21-K05 of car 6 is faulty. It then prompts the driver or technician to take emergency measures, such as pressing the "wind pressure bypass" switch of car 1, thereby ensuring the stability of train operation.

[0089] In an embodiment of the present invention, the detection method based on the online monitoring device for relays used in rail transit vehicles may further include: establishing a life model of the relay based on the relay's technical parameters, life curve, and load type; and correcting the life model of the relay based on the detection results.

[0090] Specifically, the technical parameters and lifespan curves of relays can be imported into the online monitoring device for relays in rail transit vehicles to establish a relay lifespan model. The relay's technical parameters and lifespan curves can be the parameters and curves at the time of manufacture, or parameters and curves corrected based on the original factory parameters and lifespan curves as needed. The relay lifespan model can be corrected based on test results, such as relay coil condition, contact condition, pull-in time, release time, coil resistance, and contact resistance.

[0091] In embodiments of the present invention, a lifespan model for the relay product can also be calculated based on parameters such as voltage, current, and load type of the circuit under test. By detecting the relay contact operating time and comparing it with the product's rated operating time, if the relay's response time is too long and continues to increase, an abnormal trend in the relay can be predicted, prompting manual inspection or repair / replacement, thus achieving full lifespan management. By detecting the relay coil and contact resistance and comparing it with the product's rated resistance value, if the relay coil and contact resistance increases and continues to increase, an abnormal trend in the relay can be predicted, prompting manual inspection or repair / replacement, thus achieving full lifespan management. Figure 10 As shown.

[0092] This invention enables the diagnosis and recording of relay operating status, fault analysis, and lifespan management, and allows for online downloading and uploading via wired or wireless transmission. It improves the intelligent train operation and maintenance system, fills the gap in online relay monitoring technology, and has significant practical value.

[0093] Online relay monitoring devices can improve the overall reliability of control circuits, ensure the stability of train operation, reduce maintenance costs, and improve maintenance efficiency, fundamentally solving the problem of relay troubleshooting and testing.

[0094] This application is intended to illustrate how the disclosed technology and various embodiments can be used, and is not intended to limit its true scope and equivalent spirit and meaning. Furthermore, the foregoing description is not exhaustive of all possibilities or to limit the scope of protection to the precise forms disclosed. Changes and variations are possible in accordance with the foregoing teachings. The selected and illustrated embodiments provide the best illustration of the principles of the technology and its practical application, and enable those skilled in the art to use the disclosed technology for various conceivable specific applications with various modifications. Therefore, various changes and modifications made to the above embodiments without substantially departing from the spirit and principles of the technology described herein are intended to be included within the scope of this disclosure.

Claims

1. A detection method based on an online monitoring device for relays used in rail transit vehicles, characterized in that, The online monitoring device for relays in rail transit vehicles includes: a motherboard, a main control board plugged into the motherboard, and at least one detection board. The detection board includes one of a voltage state detection board, a contact detection board, and a coil detection board. Each of the voltage state detection board, the contact detection board, and the coil detection board includes a corresponding detection circuit. The detection method includes the following steps: The detection board detects the state of the relay coil and contacts, the relay coil resistance, and / or the relay contact resistance, and sends the detection results to the main control board; and The main control board receives the detection results from the detection board and sends control data and / or fault diagnosis data based on the detection results. The voltage state detection board includes an optocoupler in its detection circuit, and the detection method includes: real-time monitoring of the relay coil and contact level signals via the optocoupler, and determining whether the relay coil and contact status is normal based on the transitions in the relay coil and contact level signals; and detecting the action time of the relay contacts based on the time difference between the transitions in the relay coil and contact level signals. The detection circuit of the coil detection board includes mechanical contacts and a semiconductor high-resistance isolation component, and the detection method includes: applying a constant current source excitation to the detection circuit of the coil detection board in response to a transition of the coil input level signal from low to high and the closure of the mechanical contacts, and calculating the resistance value of the coil based on the excitation voltage across the coil; and removing the constant current source excitation from the detection circuit of the coil detection board in response to a transition of the coil input level signal from high to low and the opening of the mechanical contacts, thereby maintaining electrical isolation between the detection circuit of the coil detection board and the circuit of the rail transit vehicle. The detection circuit of the contact detection board includes mechanical contacts and a semiconductor high-resistance isolation device, and the detection method includes: applying a constant current source excitation to the detection circuit of the contact detection board in response to a transition of the contact input level signal from low to high level and the closure of the mechanical contacts, and calculating the resistance value of the contacts based on the excitation voltage across the contacts; and removing the constant current source excitation from the detection circuit of the contact detection board in response to a transition of the contact input level signal from high to low level and the closure of the mechanical contacts, thereby maintaining electrical isolation between the detection circuit of the contact detection board and the circuit of the rail transit vehicle.

2. The detection method according to claim 1, characterized in that, The detection method includes: Compare the operating time with the rated operating time of the relay contact; Predicting abnormal trends in relays based on comparison results; and Based on the aforementioned abnormal trends, manual inspection or repair / replacement prompts will be issued.

3. The detection method according to claim 1, characterized in that, The detection method includes providing constant current source excitation through a floating isolated power supply, wherein the floating isolated power supply is completely isolated from the power supply of the rail transit vehicle.

4. The detection method according to claim 1, characterized in that, The detection method includes: Compare the resistance value of the coil with the rated resistance value of the relay coil, or compare the resistance value of the contact with the rated resistance value of the relay contact; Predicting abnormal trends in relays based on comparison results; and Based on the aforementioned abnormal trends, manual inspection or repair / replacement prompts will be issued.

5. The detection method according to claim 1, characterized in that, The detection method includes: Based on the test results, determine whether the relay and rail transit vehicle circuit are faulty; The fault diagnosis data is generated based on the judgment result; Send the detection results and / or the fault diagnosis data to the server for full lifespan monitoring and management of the relay; and / or An alarm is issued based on the detection results and / or the fault diagnosis data.

6. The detection method according to claim 1, characterized in that, The detection method includes: A life model for the relay is established based on its technical parameters, life curve, and load type. The lifespan model of the relay is corrected based on the test results.

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