A kind of brake resistance online comprehensive performance detection device

Abstract

This invention discloses an online comprehensive performance testing device for braking resistors, comprising a programmable logic controller (PLC) and connected to it a temperature sensor, a wind speed sensor, an online insulation detection device, a voltage sensor, a current sensor, a fan operating current sensor, a fan operating voltage sensor, and a vibration sensor. The temperature sensor is embedded within the braking resistor frame's output terminal to detect the spot welding temperature; the wind speed sensor detects the wind speed at the inlet and outlet; the online insulation detection device detects the insulation of the DC bus's positive and negative terminals to ground; the voltage and current sensors collect main circuit parameters; and the fan-related sensors collect the current, voltage, and vibration of the cooling fan. The controller incorporates temperature judgment logic, a duct unobstructedness judgment program, and a fan operating status judgment model, enabling comprehensive online monitoring of the resistor body, duct, and fan. This allows for precise location of insulation faults, duct blockages, and fan fault types, improving the operational safety and intelligent maintenance level of the braking resistor.

Description

Technical Field

[0001] This invention relates to the field of braking resistor testing technology, and in particular to an online comprehensive performance testing device for braking resistors. Background Technology

[0002] Resistive braking is a common braking method used in railway locomotives, urban subways, and mining vehicles. Its basic principle is as follows: when the vehicle is in resistive braking mode, the traction motor switches from motor mode to generator mode, converting the train's mechanical energy into electrical energy. This electrical energy is rectified by an inverter and applied to the braking resistor, which then converts it into heat energy. The heat energy is carried away by the cooling air blown in by the cooling fan and dissipated into the atmosphere, thus achieving energy-efficient braking.

[0003] Currently, the protection of braking resistor devices mainly relies on the following two methods: Fan pressure protection: This method determines whether the fan is working properly by detecting the pressure switch signal during operation. This requires an air pipe to deliver the air pressure to the pressure switch. Because the air pressure itself is relatively low, dust in the air can easily accumulate in the air pipe after prolonged use, causing blockage and leading to air pressure detection failure, false alarms, and affecting the normal protection function of the braking resistor.

[0004] Temperature protection for the resistance unit: A resistance value is taken from the resistive element of the braking resistor and compared with a standard resistance value. When the resistance change reaches a set threshold, an alarm is triggered. However, during operation, the braking resistor unit carries thousands of volts of high voltage. Directly reading the resistance value in this circuit can easily cause the temperature sensor to be damaged by the high voltage. In addition, if the power supply lines of the existing temperature control system are reversed, it will also damage the power supply of the temperature control system. Although some solutions have applied the braking resistor to the bridge circuit to achieve high temperature protection, they still have not fully solved the aforementioned problems of high voltage damage and wiring errors.

[0005] In summary, existing protection methods for braking resistors have drawbacks such as low detection reliability, susceptibility to environmental influences, easy sensor damage, and inability to comprehensively monitor the overall performance of the braking resistor, making it difficult to meet the safety and intelligence requirements of rail transit vehicles for braking systems. Summary of the Invention

[0006] To address the above problems, this invention provides an online comprehensive performance testing device for braking resistors, which aims to comprehensively monitor multiple key performance parameters of the braking resistor and its cooling fan, achieve accurate fault diagnosis and graded early warning, and improve the operational safety and intelligent operation and maintenance level of the braking resistor.

[0007] This invention provides an online comprehensive performance testing device for a braking resistor, including a programmable logic controller (PLC), and a temperature sensor, a wind speed sensor, an online insulation testing device, a voltage sensor, a current sensor, a fan operating current sensor, a fan operating voltage sensor, and a vibration sensor that are bidirectionally connected to the PLC. The temperature sensor is embedded in the lead end of the braking resistor frame and is in close contact with the spot welding position, and is used to detect the temperature of the spot welding position in real time. The wind speed sensor is installed at the air inlet and air outlet of the braking resistor to collect the real-time wind speed at the air inlet and air outlet. The online insulation testing device is bidirectionally connected to the DC bus of the braking resistor and the frame of the braking resistor, and is used to test the insulation performance of the positive terminal of the DC bus of the braking resistor to ground and the negative terminal to ground. The voltage sensor and current sensor are connected in series with the main circuit of the braking resistor to collect the operating voltage and operating current of the braking resistor. The fan operating current sensor, fan operating voltage sensor, and vibration sensor are all installed at the corresponding detection points of the braking resistor cooling fan, and are used to collect the operating current, operating voltage, and vibration parameters of the cooling fan, respectively.

[0008] Furthermore, the acquisition signals from the temperature sensor, wind speed sensor, online insulation detection device, voltage sensor, current sensor, fan operating current sensor, fan operating voltage sensor, and vibration sensor are all transmitted to the programmable logic controller in the form of 4-20mA analog signals.

[0009] The 4-20mA analog signal has inherent advantages such as strong anti-interference ability, long transmission distance and high accuracy. It can effectively adapt to the harsh working conditions such as strong electromagnetic interference, vibration and wide temperature fluctuation in complex industrial environments such as locomotives and subways. It ensures high-fidelity transmission of each detection parameter from the acquisition end to the control center and avoids misjudgment caused by signal attenuation or distortion, thereby significantly improving the reliability and stability of the online comprehensive performance detection of braking resistors.

[0010] Furthermore, the online insulation detection device incorporates a signal generation module and a sampling module: The signal generation module generates positive and negative symmetrical low-frequency square wave pulse signals, injects the pulse signals between the DC bus of the braking resistor and the frame of the braking resistor, and the pulse signals form a closed-loop detection circuit through the current limiting resistor series, the sampling resistor and the insulation resistance between the positive terminal and the negative terminal of the braking resistor bus to ground, and the insulation resistance between the negative terminal and the ground of the braking resistor bus. The sampling module collects the electrical signal on the sampling resistor in real time and transmits it to the programmable logic controller (PLC). The PLC has a built-in insulation resistance calculation algorithm to calculate the individual and parallel values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance, and outputs graded early warning or alarm signals based on the resistance change trend.

[0011] The signal generation module and sampling module accurately distinguish between positive and negative insulation faults to ground, avoiding missed detections caused by a decrease in insulation of one pole while the parallel value is still within the safe range. At the same time, based on the resistance change trend, it can output graded early warning or alarm signals to achieve early detection and graded response of insulation faults, providing active protection for the safe operation of the braking resistor.

[0012] Furthermore, the programmable logic controller has built-in temperature determination logic, which includes: Plot the real-time temperature change curve based on the signals collected by the temperature sensor; When the real-time temperature exceeds the over-temperature threshold, or the rate of temperature change exceeds the rate threshold, a level two alarm is triggered, and the full operating condition of the braking resistor is automatically recorded.

[0013] The built-in temperature judgment logic of the programmable logic controller can not only monitor in real time whether the absolute temperature of the solder joint of the brake resistor frame exceeds the over-temperature threshold, but also dynamically calculate the rate of temperature change. When the temperature rate is abnormal but the absolute value has not yet reached the threshold, it can detect the local overheating trend in advance, trigger an alarm, and automatically record the full operating conditions before and after the fault occurs. This provides complete data support for subsequent fault tracing, solder joint failure analysis, and preventive maintenance, significantly improving the depth and efficiency of fault diagnosis.

[0014] Furthermore, the programmable logic controller has a built-in airflow duct unobstructedness determination program, which is used for: Based on the real-time wind speeds at the air inlet and outlet, and combined with the effective ventilation areas of the air inlet and outlet, the actual air volume at the air inlet and outlet is calculated respectively. Calculate the air volume difference between the actual air volume at the air inlet and the actual air volume at the air outlet; When the actual air volume at both the air inlet and the air outlet is lower than the preset air volume protection threshold, it is determined that the entire air duct is blocked and an alarm is triggered. When the air volume difference exceeds the preset range, the corresponding blockage location is determined by comparing the actual air volume with the air volume protection threshold, and the determination result is transmitted to the driver's cab control panel.

[0015] The built-in air duct patency assessment program can accurately determine whether there is a blockage in the air duct, and whether the blockage occurs on the inlet or outlet side. This avoids false alarms caused by easy blockage of the air intake pipe and enables automatic location of the blockage. This function can guide maintenance personnel directly to the fault point for cleaning or repair, greatly shortening the troubleshooting time and improving the maintenance efficiency of the braking resistor cooling system.

[0016] Furthermore, the programmable logic controller incorporates a wind turbine operating state determination model, which is used for: The real-time collected operating voltage, operating current, and vibration values ​​of the cooling fan are compared with preset voltage thresholds, current thresholds, and vibration thresholds, respectively. The real-time impedance of the cooling fan is calculated based on the operating voltage and current of the cooling fan, and then compared with the preset impedance threshold. The fault type of the cooling fan is identified based on the comparison results and transmitted to the operator's cab control panel.

[0017] By incorporating a built-in wind turbine operating status assessment model, a multi-dimensional comprehensive evaluation of wind turbine operating status is achieved. This model can not only detect faults exceeding limits for a single parameter, but also effectively distinguish different fault types through cross-validation of four types of characteristics: voltage, current, vibration, and impedance. This avoids false alarms caused by fluctuations in a single parameter and significantly improves the accuracy and robustness of wind turbine fault diagnosis.

[0018] Furthermore, the identification of the cooling fan fault type based on the comparison results specifically includes: When the operating voltage exceeds the voltage threshold, while the operating current and vibration value are normal, it is determined to be a power supply failure of the fan. When the vibration value exceeds the vibration threshold, and the operating voltage and operating current are normal, it is determined to be a mechanical failure of the fan. When the operating current exceeds the current threshold, the real-time impedance exceeds the impedance threshold, and the operating voltage is normal, it is determined to be a fan load fault.

[0019] The above fault type judgment logic makes full use of the differences in electrical and mechanical parameters under different fault modes, and realizes the accurate classification of fault types. Operators can know the specific fault cause at the same time as receiving the alarm signal, without having to check the possibilities one by one, thereby greatly shortening the maintenance response time and improving the efficiency and accuracy of maintenance work.

[0020] Furthermore, the programmable logic controller integrates a data conversion module, a data storage module, and a communication module. The data conversion module is used to convert the acquired analog signals into actual detection values; The data storage module is used to store detection parameters, fault records, operating conditions, and temperature change curves. The communication module supports RS485 wired communication and Ethernet wireless communication, and establishes data connections with the locomotive control system and ground operation and maintenance platform to realize real-time data uploading and remote early warning.

[0021] Through data conversion, data storage, and communication modules, this device achieves real-time conversion of acquired signals, local storage of historical data, and supports RS485 wired communication and Ethernet wireless communication. It can establish remote data connections with the locomotive control system or ground maintenance platform. This enables remote monitoring, real-time uploading, and early warning of the braking resistor's operating status. Ground maintenance personnel can then conduct preventative maintenance planning and big data analysis across locomotives, truly realizing intelligent operation and maintenance management of the braking resistor throughout its entire lifecycle.

[0022] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention integrates multiple types of sensors through a programmable logic controller to construct an online comprehensive performance detection system for braking resistors, realizing all-round real-time monitoring of the resistor body, cooling duct, and fan status. Specifically, the online insulation detection device can calculate the insulation resistance values ​​of the positive and negative poles to ground separately and output graded early warnings, overcoming the shortcomings of traditional single parallel resistance value detection which cannot locate single-pole faults; the temperature judgment logic simultaneously monitors absolute temperature and temperature rise rate, and can automatically record all operating conditions before and after a fault, providing data support for weld joint failure analysis; the duct unobstructedness judgment program can accurately locate the blockage location, avoiding the problems of easy blockage and false alarms in traditional air pressure pipes; the fan operating status judgment model, through four-dimensional cross-comparison of voltage, current, vibration, and impedance, can accurately distinguish between power supply faults, mechanical faults, and load faults, significantly improving the accuracy of fault diagnosis and maintenance efficiency. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the device of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0026] This invention provides an online comprehensive performance testing device for braking resistors, such as... Figure 1 As shown, the system includes a programmable logic controller (PLC), and temperature sensors, wind speed sensors, an online insulation detection device, voltage sensors, current sensors, a fan operating current sensor, a fan operating voltage sensor, and vibration sensors, all bidirectionally connected to the PLC. The PLC, as the core control unit, is installed in the locomotive's electrical cabinet. It has a bidirectional signal connection to the driver's cab control panel, enabling it to output alarm and fault information to the control panel, as well as receive commands from the control panel for parameter setting, threshold adjustment, and data querying.

[0027] The temperature sensor employs a high-temperature, high-pressure ceramic-encapsulated PT100 sensor, embedded inside the lead-out end of the braking resistor frame. Its sensing end is in close contact with the spot-welded position of the lead-out end and the resistor strip, enabling precise real-time temperature detection of the solder joint. The temperature measurement range is set from -50℃ to 500℃, covering all operating conditions of the braking resistor under no-load, light-load, and heavy-load conditions. The temperature sensor acquires the solder joint temperature at a sampling frequency of 5Hz and transmits the temperature signal to the programmable logic controller (PLC).

[0028] The wind speed sensor is an anti-clogging type wind speed transmitter. One anti-clogging wind speed transmitter is installed at the air inlet and one at the air outlet of the braking resistor to collect real-time wind speeds at these locations. The sensing end of each transmitter employs a dust-proof structure to prevent clogging, making it suitable for the high-dust working environment of the braking resistor. Both wind speed transmitters collect real-time wind speeds at their respective locations at a sampling frequency of 5Hz and transmit the wind speed signals to the programmable logic controller (PLC).

[0029] The online insulation testing device is a dedicated insulation monitoring instrument. Its signal output terminal is connected to the DC bus of the braking resistor, and its grounding terminal is connected to the frame (earth) of the braking resistor. It is used to test the insulation performance of the positive and negative terminals of the DC bus of the braking resistor to ground.

[0030] Furthermore, the online insulation detection device incorporates a signal generation module and a sampling module: The signal generation module generates a positive and negative symmetrical low-frequency square wave pulse signal with an amplitude of ±25V, which is injected between the DC bus of the braking resistor and the frame (ground) of the braking resistor. The pulse signal forms a closed-loop detection circuit through the current limiting resistor RX, the high-voltage relay, the sampling resistor RS, and the insulation resistance RISO+ and RISO- of the positive and negative terminals of the braking resistor bus to ground. The sampling module acquires the electrical signal on the sampling resistor RS in real time and transmits it to the programmable logic controller.

[0031] A voltage sensor and a current sensor are connected in series to the main circuit of the braking resistor to collect the operating voltage and operating current of the braking resistor, respectively.

[0032] The fan operating current sensor and the fan operating voltage sensor are connected in series in the power supply circuit of the cooling fan to collect the operating current and operating voltage of the cooling fan, respectively; the vibration sensor is installed at the fan base, and its detection direction covers the fan axial and radial directions to collect vibration parameters.

[0033] All signals acquired by the aforementioned sensors and detection devices are transmitted to the programmable logic controller (PLC) in the form of 4-20mA analog signals. 4-20mA analog signals are characterized by strong anti-interference capabilities, long transmission distances, and high accuracy, making them suitable for complex industrial environments such as locomotives and subways.

[0034] The programmable logic controller (PLC) integrates a data conversion module, a parameter calculation module, a fault diagnosis module, a graded early warning module, a data storage module, and a communication module. The data conversion module converts the acquired 4-20mA analog signal into actual measured values ​​such as temperature, wind speed, voltage, current, and vibration. The parameter calculation module completes the calculation of secondary parameters such as insulation resistance, air volume, and fan impedance; The fault diagnosis module uses built-in algorithms and diagnosis models to accurately identify fault types and fault locations. The graded early warning module outputs a first-level early warning or a second-level alarm signal based on the severity of the fault. The data storage module has a large storage capacity, capable of storing at least 6 months of detection parameters, fault records, operating conditions and temperature change curves, and supports local query and remote retrieval of historical data; The communication module supports RS485 wired communication and Ethernet wireless communication, and can establish data connection with the locomotive control system and ground operation and maintenance platform to realize real-time uploading of detection data and remote early warning of fault information. Ground operation and maintenance personnel can monitor the working status of multiple locomotive braking resistors in real time through the platform, formulate preventive maintenance plans, and realize full life cycle management of braking resistors.

[0035] The specific implementation process of the temperature protection function is as follows: After receiving the temperature signal, the programmable logic controller (PLC) plots a real-time temperature change curve and executes the following temperature determination logic: it compares the current temperature with a preset over-temperature threshold (e.g., 300℃), calculates the temperature change rate, and compares it with a preset rate threshold (e.g., 20℃ / minute).

[0036] When the real-time temperature exceeds the over-temperature threshold, or the rate of temperature change exceeds the rate threshold, it is determined that the solder joint temperature is abnormal. The programmable logic controller immediately triggers a level two alarm, outputs a red alarm signal to the driver's cab control panel, and automatically records the full operating conditions of the braking resistor, including parameters such as operating voltage, operating current, inlet air velocity, outlet air velocity, inlet air volume, outlet air volume, fan operating voltage, fan operating current, and fan vibration value.

[0037] Operators can use the control panel in the driver's cab to check the temperature change curve and the full operating conditions at the time of the fault, providing complete data support for troubleshooting faults such as weld cracking and local overheating.

[0038] The specific implementation process of air duct unobstructedness detection and blockage location is as follows: Pre-enter the effective ventilation area of ​​the air inlet and outlet of the braking resistor (e.g., air inlet area 0.5m²). 2 Air outlet area 0.6m² 2 The collected wind speed signals are multiplied by the corresponding effective ventilation area to calculate the actual air volume at the air inlet and outlet. The air volume difference between the actual air volume at the air inlet and outlet is calculated, and then compared with a preset air volume protection threshold (e.g., 1.5m). 3 The airflow difference is compared with the preset range (e.g., less than or equal to 0.2m / s). 3 Compare using / s).

[0039] When the actual air volume of both the air inlet and the air outlet is lower than the air volume protection threshold, it is determined that the air duct is blocked and a red alarm signal is output to the driver's cab control panel. When the air volume difference exceeds the preset range, further judgment is made: if the air volume at the air inlet is normal and the air volume at the air outlet is lower than the threshold, it is determined that the air outlet is blocked; if the air volume at the air outlet is normal and the air volume at the air inlet is lower than the threshold, it is determined that the air inlet is blocked.

[0040] The judgment results are transmitted to the driver's cab control screen in real time for display, guiding maintenance personnel to go directly to the blockage location for clearing, eliminating the need for step-by-step inspection and greatly improving maintenance efficiency.

[0041] The specific implementation process of the online insulation detection function is as follows: The programmable logic controller (PLC) incorporates an insulation resistance calculation algorithm. It calculates the individual resistance values ​​of RISO+ and RISO- separately, or the parallel value RISO of RISO+ and RISO-, by sampling the electrical signal on resistor RS. Simultaneously, the PLC determines the development level of the insulation fault based on the resistance change trends of RISO+ and RISO-: when the insulation resistance of RISO+ or RISO- shows a slight decrease but remains above the safety threshold, a level one warning signal is output; when the insulation resistance of RISO+ or RISO- falls below the preset safety threshold, a level two alarm signal is output. These tiered warning signals are transmitted in real-time to the operator's control panel in the driver's cab, alerting the operator to take timely action, thus achieving early detection and tiered response to insulation faults.

[0042] The specific implementation process for cooling fan operating status detection and fault identification is as follows: The programmable logic controller has a built-in fan operating status determination model. The rated operating parameters and protection thresholds of the fan are pre-entered. The real-time collected cooling fan operating voltage U, operating current I, and vibration value are compared with the corresponding protection thresholds. The real-time impedance of the cooling fan Z=U / I is calculated and compared with the rated impedance and impedance threshold.

[0043] When the operating voltage exceeds the voltage threshold, but the operating current and vibration value are normal, it is determined to be a power supply failure of the fan. When the vibration value exceeds the vibration threshold, but the operating voltage and operating current are normal, it is determined to be a mechanical fault of the fan (including bearing wear, impeller jamming, loose base, etc.). When the operating current exceeds the current threshold, the real-time impedance exceeds the impedance threshold, but the operating voltage is normal, it is determined to be a fan load fault.

[0044] The programmable logic controller transmits the identified fault types to the driver's cab control panel in real time for display. Operators can directly locate the cause of the fault based on the fault type, significantly shortening the maintenance response time.

[0045] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A device for online comprehensive performance testing of braking resistors, characterized in that, This includes a programmable logic controller (PLC), as well as temperature sensors, wind speed sensors, online insulation detection devices, voltage sensors, current sensors, fan operating current sensors, fan operating voltage sensors, and vibration sensors that are bidirectionally connected to the PLC. The temperature sensor is embedded in the lead end of the braking resistor frame and is in close contact with the spot welding position, and is used to detect the temperature of the spot welding position in real time. The wind speed sensor is installed at the air inlet and air outlet of the braking resistor to collect the real-time wind speed at the air inlet and air outlet. The online insulation testing device is bidirectionally connected to the DC bus of the braking resistor and the frame of the braking resistor, and is used to test the insulation performance of the positive terminal of the DC bus of the braking resistor to ground and the negative terminal to ground. The voltage sensor and current sensor are connected in series with the main circuit of the braking resistor to collect the operating voltage and operating current of the braking resistor. The fan operating current sensor, fan operating voltage sensor, and vibration sensor are all installed at the corresponding detection points of the braking resistor cooling fan, and are used to collect the operating current, operating voltage, and vibration parameters of the cooling fan, respectively.

2. The online comprehensive performance testing device for braking resistors according to claim 1, characterized in that, The signals acquired by the temperature sensor, wind speed sensor, online insulation detection device, voltage sensor, current sensor, fan operating current sensor, fan operating voltage sensor, and vibration sensor are all transmitted to the programmable logic controller in the form of 4-20mA analog signals.

3. The online comprehensive performance testing device for braking resistors according to claim 1, characterized in that, The online insulation detection device has a built-in signal generation module and a sampling module: The signal generation module generates positive and negative symmetrical low-frequency square wave pulse signals, injects the pulse signals between the DC bus of the braking resistor and the frame of the braking resistor, and the pulse signals form a closed-loop detection circuit through the current limiting resistor series, the sampling resistor and the insulation resistance between the positive terminal and the negative terminal of the braking resistor bus to ground, and the insulation resistance between the negative terminal and the ground of the braking resistor bus. The sampling module collects the electrical signal on the sampling resistor in real time and transmits it to the programmable logic controller (PLC). The PLC has a built-in insulation resistance calculation algorithm to calculate the individual and parallel values ​​of the positive-to-ground insulation resistance and the negative-to-ground insulation resistance, and outputs graded early warning or alarm signals based on the resistance change trend.

4. The online comprehensive performance testing device for braking resistors according to claim 1, characterized in that, The programmable logic controller has built-in temperature determination logic, which includes: Plot the real-time temperature change curve based on the signals collected by the temperature sensor; When the real-time temperature exceeds the over-temperature threshold, or the rate of temperature change exceeds the rate threshold, a level two alarm is triggered, and the full operating condition of the braking resistor is automatically recorded.

5. The online comprehensive performance testing device for braking resistors according to claim 1, characterized in that, The programmable logic controller has a built-in air duct unobstructedness determination program, which is used for: Based on the real-time wind speeds at the air inlet and outlet, and combined with the effective ventilation areas of the air inlet and outlet, the actual air volume at the air inlet and outlet is calculated respectively. Calculate the air volume difference between the actual air volume at the air inlet and the actual air volume at the air outlet; When the actual air volume at both the air inlet and the air outlet is lower than the preset air volume protection threshold, it is determined that the entire air duct is blocked and an alarm is triggered. When the air volume difference exceeds the preset range, the corresponding blockage location is determined by comparing the actual air volume with the air volume protection threshold, and the determination result is transmitted to the driver's cab control panel.

6. The online comprehensive performance testing device for braking resistors according to claim 1, characterized in that, The programmable logic controller has a built-in fan operating status determination model, which is used for: The real-time collected operating voltage, operating current, and vibration values ​​of the cooling fan are compared with preset voltage thresholds, current thresholds, and vibration thresholds, respectively. The real-time impedance of the cooling fan is calculated based on the operating voltage and current of the cooling fan, and then compared with the preset impedance threshold. The fault type of the cooling fan is identified based on the comparison results and transmitted to the operator's cab control panel.

7. The online comprehensive performance testing device for braking resistors according to claim 6, characterized in that, The method of identifying the fault type of the cooling fan based on the comparison results specifically includes: When the operating voltage exceeds the voltage threshold, while the operating current and vibration value are normal, it is determined to be a power supply failure of the fan. When the vibration value exceeds the vibration threshold, and the operating voltage and operating current are normal, it is determined to be a mechanical failure of the fan. When the operating current exceeds the current threshold, the real-time impedance exceeds the impedance threshold, and the operating voltage is normal, it is determined to be a fan load fault.

8. The online comprehensive performance testing device for braking resistors according to claim 2, characterized in that, The programmable logic controller has a built-in data conversion module, data storage module, and communication module. The data conversion module is used to convert the acquired analog signals into actual detection values; The data storage module is used to store detection parameters, fault records, operating conditions, and temperature change curves. The communication module supports RS485 wired communication and Ethernet wireless communication, and establishes data connections with the locomotive control system and ground operation and maintenance platform to realize real-time data uploading and remote early warning.

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