Relay contact resistance and current online monitoring system and method

Abstract

A relay contact resistance and current on-line monitoring system and method belong to the technical field of real-time on-line monitoring of railway signal equipment and comprise a core data processing module, a contact voltage test module, a contact current test module, a data transmission module, a coil voltage acquisition module and a power supply module. The core data processing module is respectively connected with the contact voltage test module, the contact current test module, the data transmission module and the coil voltage acquisition module, the contact voltage test module is connected with a normally open contact or a normally closed contact of a relay, and the contact current test module is connected with a conversion contact of the relay. And the coil voltage acquisition module is connected with a coil terminal of the relay. The relay contact resistance value is reported in real time in the working process of the relay, and therefore the problem that faults caused by the fact that the relay contact resistance exceeds the standard cannot be prevented and processed in time is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of real-time online monitoring of railway signal equipment, and in particular relates to a system and method for online monitoring of relay contact resistance and current. Background Art

[0002] The stepless relay is a typical model of the AX series relay. It consists of two major parts: the electromagnetic system and the contact system. It is widely used in railway signal control circuits such as turnout control circuits, route locking circuits, signal control circuits, route unlocking circuits, guide signal circuits, and reverse circuits. The magnetic circuit system controls the connection of the moving contact of the contact system and the connection of the moving contact to achieve the overall circuit function.

[0003] In daily use, because the standard value of relay contact resistance is required to be less than 50mΩ, the current technical level cannot realize real-time monitoring of relay contact resistance when the relay is working, and the contact test can only be realized by using a micro-ohmmeter when the relay is not working. The fault of increased relay contact resistance can only be discovered when the overall circuit function fails, which is not conducive to improving the overall operation efficiency of the railway and conducting preventive maintenance analysis. Summary of the invention

[0004] In view of the above-mentioned shortcomings and deficiencies of the prior art, the technical problem to be solved by the present invention is that the relay cannot report the relay contact resistance value in real time during operation to achieve preventive maintenance. By using the present system, the monitored relay contact resistance and current values ​​can be uploaded to the monitoring center in real time. The monitoring center sets a pre-alarm threshold to remind on-site maintenance personnel to perform preventive maintenance on the relay before the relay fails, thereby solving the problem that the fault caused by the relay contact resistance exceeding the standard cannot be prevented and handled in time.

[0005] In order to solve the above technical problems, the main technical solutions adopted by the present invention include: A relay contact resistance and current online monitoring system comprises a core data processing module, a contact voltage test module, a contact current test module, a data transmission module, a coil voltage acquisition module and a power supply module. The core data processing module is respectively connected to the contact voltage test module, the contact current test module, the data transmission module and the coil voltage acquisition module; the power supply module is connected to the core data processing module, the contact voltage test module, the contact current test module, the data transmission module and the coil voltage acquisition module; the contact voltage test module is connected to a make contact or a break contact of a relay; the contact current test module is connected to a switching contact of a relay; and the coil voltage acquisition module is connected to a coil terminal of the relay.

[0006] Furthermore, the contact current testing module includes eight groups of contact current testing circuits, each group of contact current testing circuits includes a current sampling resistor Rx, the current sampling resistor Rx is connected in series to the conversion contact loop of the relay, and the differential input ports CH1 and CH2 of the analog-to-digital converter chip U1 are respectively connected to the two ends of the current sampling resistor Rx through isolation resistors R1 and R2.

[0007] Furthermore, the resistance of the current sampling resistor Rx is 1 mΩ, and the resistance of the isolation resistors R1 and R2 is greater than 100 KΩ.

[0008] Furthermore, the contact voltage test module includes eight groups of contact voltage test circuits, each group of contact voltage test circuits includes first to third measurement circuits, the first to third measurement circuits are respectively connected to the break contact, the make contact, and the conversion contact of the relay, each measurement circuit includes an isolation resistor, two voltage-dividing resistors, and a filter capacitor, one end of one of the voltage-dividing resistors in each measurement circuit is connected in parallel with the filter capacitor and is grounded, and the other end is connected to another voltage-dividing resistor, and the other end of the other voltage-dividing resistor is connected to the contact of the relay through the isolation resistor, and the sampling voltages AD1, AD2, and AD3 of each measurement circuit are input into the ADC chip to obtain the sampled voltage value.

[0009] Furthermore, the resistance of the isolation resistor is greater than 100K, the filter capacitor is 100nF, and the voltage divider resistor converts the measured voltage into a voltage range input by an analog-to-digital converter ADC chip.

[0010] The method for online monitoring of relay contact resistance and current using the system comprises the following steps: Step S01, the core data processing module reads the coil voltage through the coil voltage acquisition module; Step S02, the core data processing module controls the contact current test module, reads the voltage of the sampling resistor in the contact current test module in real time, and calculates the current of the relay contact; Step S03: The core data processing module controls the contact voltage test module to read the contact voltage of the relay contact in real time, and calculates the contact resistance of the relay contact according to the read contact current; Step S04, the core data processing module controls the working state of the relay by reading the coil voltage value and the contact resistance of the relay; Step S05, the core data processing module automatically transmits the read contact resistance and contact current information, and the working status information of the relay to the monitoring center through the data transmission module in a wireless LORA manner.

[0011] Further, in step S04, when the coil voltage read exceeds 16.8V, and the contact resistance between the relay's make contact and the conversion contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be that the conversion contact is connected to the make node; when the voltage read is less than 3.4V, and the existence between the relay's make contact and the conversion contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be that the conversion contact is connected to the break node; other situations are reported as abnormal.

[0012] The beneficial effects of the present invention are: 1. Compared with the prior art, the present invention adopts real-time online monitoring, which can monitor the operating parameters of the relay in the working state, monitor the working performance of the relay in real time, and discover the hidden dangers in the relay work in advance, so as to solve the problem before the failure occurs. At the same time, after the failure occurs, real-time fault location can be realized, and fault maintenance can be carried out in time, thereby improving the efficiency of railway operation; 2. The contact current test module of the present invention connects a high-precision 1 milliohm current sampling resistor in series on the conversion contact, and performs differential processing on the sampling input at the same time, and uses a differential signal mode to test the voltage, which reduces the interference of external signals and ensures the accuracy of the test. It is used in combination with an ADC with differential input to provide a clear current signal for the core processing module. At the same time, accurate monitoring of 1mA current can be achieved under the above circuit conditions; 3. The sampling point of the contact voltage test module of the present invention is connected in series with a large-resistance isolation resistor, and a filter inductor and capacitor are added to suppress electromagnetic compatibility (EMC) interference and ensure that the relay contacts will not be affected when the monitoring circuit fails. At the same time, under the precise current test conditions of the contact current test module, the test accuracy can reach 1mΩ. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the system block diagram of the relay contact resistance and current online monitoring system; Figure 2 It is a contact current test module; Figure 3 It is the contact voltage test module.

[0014] In the figure: 1 is the core data processing module, 2 is the contact voltage test module, 3 is the contact current test module, 4 is the data transmission module, 5 is the coil voltage acquisition module, and 6 is the power supply module. DETAILED DESCRIPTION

[0015] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0016] The present invention discloses an online monitoring system for relay contact resistance and current and an implementation method thereof, which are used to realize real-time monitoring of the contact resistance and the contact current of the relay under online working conditions, and can provide real-time feedback on the contact characteristics of the relay. By monitoring the online working status of the relay, the relay user can be helped to prevent and locate faults in a timely manner, thereby improving the efficiency of on-site maintenance operations.

[0017] like Figure 1 As shown, the present invention provides a relay contact resistance and current online monitoring system, including a core data processing module 1, a contact voltage test module 2, a contact current test module 3, a data transmission module 4, a coil voltage acquisition module 5, and a power supply module 6. The core data processing module 1 is respectively connected to the contact voltage test module 2, the contact current test module 3, the data transmission module 4, and the coil voltage acquisition module 5 through a data bus. The power supply module 6 is connected to the core data processing module 1, the contact voltage test module 2, the contact current test module 3, the data transmission module 4, and the coil voltage acquisition module 5 through a power line in a printed circuit board. The contact voltage test module 2 is connected to the make contact or break contact of the relay through a relay base. The contact current test module 3 is connected to the switching contact of the relay through a relay base. The coil voltage acquisition module 5 is connected to the coil terminal of the relay through a relay base. The power supply module 6 is connected to a 24V power supply through a power line.

[0018] The present invention also provides a method for realizing a relay contact resistance and current online monitoring system, comprising the following steps: 1) The core data processing module first reads the coil voltage through the coil voltage acquisition module.

[0019] 2) The core data processing module controls the contact current test module, reads the voltage of the sampling resistor in the contact current test module in real time, and calculates the current of the eight groups of contacts of the relay.

[0020] 3) The core data processing module controls the contact voltage test module to read the contact voltage of the relay contacts in real time, and calculates the contact resistance of the current 8 groups of contacts of the relay based on the read contact current.

[0021] 4) The core data processing module controls the working state of the relay by reading the coil voltage value and the contact resistance of the relay. When the coil voltage read exceeds 16.8V, and the contact resistance between the relay's make-or-break contact and the transfer contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be the transfer contact connected to the make-or-break node. When the voltage read is less than 3.4V, and the resistance between the relay's make-or-break contact and the transfer contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be the transfer contact connected to the break node. Other situations are reported as abnormal.

[0022] 5) The core data processing module will read the 8 groups of contact resistance and 8 groups of contact current information, and the working status information of the relay, and automatically transmit the monitoring data to the monitoring center in a wireless LORA manner through the data transmission module. The monitoring center can monitor each relay installed with this device in real time.

[0023] The core part of the core processing module is the core processing CPU, model STM32F103CBT6. The LORA module model used in the data transmission module is LRNWB25. The core processing module automatically transmits the monitoring data to the monitoring center by controlling the data transmission module to connect with external devices. The power supply module is a 24V to 3.3V power supply circuit, and the linear voltage regulator model is TPS7B92033.

[0024] The contact current test module contains 8 groups such as Figure 2 The circuit shown. Figure 2 In the field application, open the access cable of the relay's transfer contact. Figure 2 Connect one end of Rx to the relay, and connect the other end of Rx to the switching contact of the relay. Figure 2 The current sampling resistor Rx is connected in series to the switching contact loop of the relay. The differential input ports CH1 and CH2 of the analog-to-digital converter chip U1 are connected to the two ends of the current sampling resistor Rx through isolation resistors R1 and R2, respectively, where the resistance of Rx is 1mΩ, and the resistance of R1 and R2 is greater than 100KΩ.

[0025] Rx is a standard sampling resistor with a resistance of 1mΩ. Rx is connected in series with the relay contact to be measured. Because its resistance is very small, the impact on the contact parameters can be ignored. R1 and R2 are isolation resistors with a resistance greater than 100KΩ to reduce the impact of the post-stage sampling circuit on the contact parameters. U1 is a differential input ADC (analog-to-digital converter) chip. When the relay's make or break contacts are connected to the circuit, current passes through Rx, generating a voltage across Rx. U1 measures the voltage value through the differential input ports CH1 and CH2, and uses the voltage value divided by the standard resistance of 1mΩ to calculate the measured current value of the contact.

[0026] The contact voltage test module contains 8 groups such as Figure 3 As shown in the circuit. Figure 3In the figure, K1 is the relay contact terminal. When used on site, connect the A end of R1 in the figure to the break contact of the input relay, the B end of R4 to the close contact of the relay, and the C end of R7 to the switching contact of the relay. Use three sets of circuits to measure the voltage on contact line 1, line 2, and line 3 respectively. The voltage measurement process on line 1, line 2, and line 3 is as follows: R1, R4, and R7 are isolation resistors with a resistance greater than 100K to reduce the influence of the post-stage sampling circuit on the contact parameters; R2, R3, R5, R6, R8, and R9 are voltage divider resistors to convert the measured voltage into a voltage range suitable for the ADC (analog-to-digital converter) chip input; C1, C2, and C3 are 100nF filter capacitors, and the sampling voltages AD1, AD2, and AD3 are input to the ADC chip to obtain the sampled voltage value.

[0027] The coil voltage acquisition module uses the mature A / D (analog-to-digital conversion) method for measurement. The measured voltage is filtered and then enters the ADC (analog-to-digital converter) for acquisition. After calculation, the measured voltage value is obtained to realize the measurement of the input voltage of the input relay coil. The present invention will periodically read the above data at a certain time interval, and periodically upload the test data to the monitoring center at a certain time interval.

[0028] The specific implementation method is as follows: After the monitoring system is powered on, the power module converts the input 24V power supply into 3.3V power supply for use by other modules. The core data processing module first reads the coil voltage through the coil voltage acquisition module, determines the working status of the relay, and records it. Then the core data processing module controls the current test module, reads the voltage of the sampling resistor in the current test module, calculates the current of the 8 groups of break contacts or close contacts of the relay, and records it. Then the core data processing module controls the contact voltage test module, reads the contact voltage of the relay contact in real time, and calculates the contact resistance of the current 8 groups of contacts of the relay based on the read contact current, and records it. Then the core data processing module automatically transmits the working status information of the relay, 8 groups of contact resistance and 8 groups of contact current information to the monitoring center through the data transmission module in a wireless LORA manner. The monitoring center can monitor each relay installed with this device in real time. The above working process is once every 500ms. The monitoring center updates the contact characteristics of the feedback relay every 500ms based on the received information and displays the working status of the relay, helping relay users to prevent and locate faults in a timely manner and improve the efficiency of on-site maintenance operations.

[0029] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. Alterations, modifications, substitutions and variations of the above embodiments by a person skilled in the art are all within the scope of the present invention.

Claims

1. A relay contact resistance and current online monitoring system, characterized in that: It includes a core data processing module, a contact voltage test module, a contact current test module, a data transmission module, a coil voltage acquisition module, and a power supply module. The core data processing module is respectively connected to the contact voltage test module, the contact current test module, the data transmission module, and the coil voltage acquisition module. The power supply module is connected to the core data processing module, the contact voltage test module, the contact current test module, the data transmission module, and the coil voltage acquisition module. The contact voltage test module is connected to the make contact or break contact of the relay, the contact current test module is connected to the switching contact of the relay, and the coil voltage acquisition module is connected to the coil terminal of the relay.

2. A relay contact resistance and current online monitoring system according to claim 1, characterized in that: The contact current test module includes eight groups of contact current test circuits, each group of contact current test circuits includes a current sampling resistor Rx, the current sampling resistor Rx is connected in series to the conversion contact loop of the relay, and the differential input ports CH1 and CH2 of the analog-to-digital converter chip U1 are connected to the two ends of the current sampling resistor Rx through isolation resistors R1 and R2 respectively.

3. A relay contact resistance and current online monitoring system according to claim 2, characterized in that: The resistance of the current sampling resistor Rx is 1mΩ, and the resistance of the isolation resistors R1 and R2 is greater than 100KΩ.

4. The relay contact resistance and current online monitoring system according to claim 1, characterized in that: The contact voltage test module includes eight groups of contact voltage test circuits, each group of contact voltage test circuits includes first to third measuring circuits, the first to third measuring circuits are respectively connected to the break contact, the make contact and the conversion contact of the relay, each measuring circuit includes an isolation resistor, two voltage-dividing resistors and a filter capacitor, one end of one of the voltage-dividing resistors in each measuring circuit is connected in parallel with the filter capacitor and grounded, and the other end is connected to another voltage-dividing resistor, and the other end of the other voltage-dividing resistor is connected to the contact of the relay through the isolation resistor, and the sampling voltages AD1, AD2 and AD3 of each measuring circuit are input into the ADC chip to obtain the sampled voltage value.

5. A relay contact resistance and current online monitoring system according to claim 4, characterized in that: The resistance of the isolation resistor is greater than 100K, the filter capacitor is 100nF, and the voltage divider resistor converts the measured voltage into the voltage range of the analog-to-digital converter ADC chip input.

6. A method for online monitoring of relay contact resistance and current using the system of any one of claims 1 to 5, characterized in that: The steps include: Step S01, the core data processing module reads the coil voltage through the coil voltage acquisition module; Step S02, the core data processing module controls the contact current test module, reads the voltage of the sampling resistor in the contact current test module in real time, and calculates the current of the relay contact; Step S03: The core data processing module controls the contact voltage test module to read the contact voltage of the relay contact in real time, and calculates the contact resistance of the relay contact according to the read contact current; Step S04, the core data processing module controls the working state of the relay by reading the coil voltage value and the contact resistance of the relay; Step S05, the core data processing module automatically transmits the read contact resistance and contact current information, and the working status information of the relay to the monitoring center through the data transmission module in a wireless LORA manner.

7. The method for online monitoring of relay contact resistance and current according to claim 6, characterized in that: In the step S04, when the coil voltage read exceeds 16.8V, and the contact resistance between the relay's make contact and the conversion contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be that the conversion contact is connected to the make node; when the voltage read is less than 3.4V, and the existence between the relay's make contact and the conversion contact is greater than 5 milliohms and less than 50 milliohms, the relay working state is judged to be that the conversion contact is connected to the break node; other situations are reported as abnormal.

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