Gas density relay contact closure self-diagnostic device and method

Abstract

The application discloses a kind of gas density relay contact closure self-diagnosis device and method, device includes control unit, contact signal transmission module and contact module, the front stage of contact signal transmission module is connected contact module, the rear stage is connected control unit, contact signal transmission module includes photoelectric coupler OC1 and photoelectric coupler OC2, photoelectric coupler OC1 and photoelectric coupler OC2 are placed in amplification circuit feedback loop;Delay module includes photoelectric coupler OC3, relay RR1, same direction buffer G1 and electromagnet A3, the light-emitting diode in photoelectric coupler OC3 is connected the output of control unit, same direction buffer G1 and electromagnet A3 are connected after one end of series, another end is accessed triode's emitter in photoelectric coupler OC3 through relay RR1 triode's collector in photoelectric coupler OC3;The self-diagnosis process of the application to contact closure, avoid due to the contact mis-trigger caused by vibration and timely discovery contact overpressure alarm signal.

Description

Technical Field

[0001] This invention relates to the field of power technology, specifically to a gas density relay contact closure self-diagnosis device and method. Background Technology

[0002] Sulfur hexafluoride (SF6) gas is widely used in electrical equipment due to its excellent insulating properties. SF6 gas density relays are crucial components in SF6 electrical equipment, primarily used to monitor the density of SF6 gas inside high-voltage equipment. The density relay contains contacts and a control circuit, connected to the gas chamber of the electrical equipment, and monitors changes in SF6 gas density in real time. When a leak occurs in the gas chamber of the high-voltage electrical equipment, causing a drop in SF6 gas density, the density relay activates its contacts, generating alarm and interlock signals, enabling timely response to safety issues with the electrical equipment.

[0003] Currently, microswitches are commonly used in density relays due to their compact internal structure, tiny contact gaps, and high sensitivity. However, in practical applications, their vibration resistance is generally poor. During the opening or closing of electrical equipment, vibrations can occur on the density relay, potentially causing false triggering of alarm and interlock signals, especially when the gas density value is close to the alarm or interlock point. To address this issue of false triggering of microswitches caused by vibration, patent document CN103594284A proposes a sulfur hexafluoride gas density relay that employs an anti-misoperation mechanism to prevent false triggering of the microswitch during the impact and vibration generated by the opening and closing of the switch.

[0004] Meanwhile, electrical equipment operating in high-temperature and humid environments for extended periods, or experiencing insulation aging or improper operation, may generate internal fault arcs. The high temperature generated by these arcs causes a rapid increase in internal air pressure, triggering an overpressure alarm at the contacts. The fault arc lasts only a short time; afterward, the internal air pressure drops to normal, and the overpressure alarm signal is deactivated. If the control system fails to detect this fault arc in time, it poses a significant safety hazard. Therefore, timely and accurate diagnosis of density relay contact signals is crucial for the safety of electrical equipment.

[0005] In related technologies, patent application CN114420500A proposes an intelligent gas density relay that can prevent malfunctions. The gas density relay includes a malfunction judgment module and a malfunction delay communication module. The malfunction delay communication module delays the time it takes for the control signal to be transmitted to the electrical equipment under test when the relay contacts close due to a malfunction, thus avoiding malfunctions of the SF6 gas density relay contacts. However, the malfunction delay communication module in this solution uses a resistor-inductor series structure RL, and the delay is achieved by controlling the current through the charging and discharging of RL. The control accuracy is not high, and there is a certain amount of interference.

[0006] The patent application document with publication number CN107872214A discloses an anti-interference optocoupler relay, which includes a coupling circuit, a zero-crossing drive circuit, and a switching circuit; wherein the zero-crossing drive circuit is used for delayed triggering and is mainly composed of an operational amplifier and a diode.

[0007] Patent application CN111681909A discloses a gas density relay with contact wiring diagnosis function, which includes a contact wiring condition diagnosis unit. The unit receives and / or diagnoses the data and / or information monitored by the contact wiring condition diagnosis unit to obtain the wiring condition of the contacts of the gas density relay body. However, in this solution, the contact wiring condition diagnosis unit is composed of an optocoupler. Since the light-emitting diode inside the optocoupler has unidirectional conductivity and severe nonlinearity, directly using the optocoupler to transmit signals has problems in practical applications. Summary of the Invention

[0008] The technical problem to be solved by this invention is how to avoid false triggering of the contact due to vibration and timely detection of contact overpressure alarm signals during the self-diagnosis process of contact closure.

[0009] The present invention solves the above-mentioned technical problems through the following technical means: On one hand, the present invention proposes a gas density relay contact closure self-diagnostic device, the device comprising: a control unit, a contact signal transmission module and a contact module, wherein the front end of the contact signal transmission module is connected to the contact module and the rear end is connected to the control unit, the output of the control unit is connected to the delay module, and the contact module is connected to the contact interlock / alarm circuit; The contact signal transmission module includes optocoupler OC1 and optocoupler OC2, which are placed in the feedback loop of the amplifier circuit and the light-emitting diodes in optocoupler OC1 and optocoupler OC2 are connected in series. The delay module includes an optocoupler OC3, a relay RR1, a non-inverting buffer G1, and an electromagnet A3. The light-emitting diode in the optocoupler OC3 is connected to the output of the control unit. One end of the non-inverting buffer G1 and the electromagnet A3 connected in series is connected to the collector of the transistor in the optocoupler OC3 via the relay RR1, and the other end is connected to the emitter of the transistor in the optocoupler OC3.

[0010] Furthermore, the feedback loop of the amplifier circuit includes operational amplifier A1 and operational amplifier A2; Operational amplifier A1 is connected between optocoupler OC1 and optocoupler OC2, and operational amplifier A2 is connected to the transistor in optocoupler OC1.

[0011] Furthermore, the positive input terminal of operational amplifier A1 is connected to the positive power supply interface and then connected to the collector of the transistor in optocoupler OC2. The negative input terminal of operational amplifier A1 is connected to the control unit. The output terminal of operational amplifier A1 is connected to the positive terminal of the light-emitting diode in optocoupler OC1 via a resistor. The negative power supply interface of operational amplifier A1 is connected to the emitter of the transistor in optocoupler OC2. The positive input terminal of operational amplifier A2 is connected to the positive power supply interface and then connected to the collector of the transistor in optocoupler OC1. The negative power supply interface of operational amplifier A2 is connected to the emitter of the transistor in optocoupler OC1.

[0012] Furthermore, diode D1 and resistor R9 are connected in series and then in parallel across the two ends of the non-inverting buffer G1. One end of the non-inverting buffer G1 is connected to resistor R8 and capacitor C2 respectively, and the other end of the non-inverting buffer G1 is connected to electromagnet A3. Electromagnet A3 is connected to the emitter of the transistor in optocoupler OC3 after being connected to resistor R8. Capacitor C2 is connected to the collector of the transistor in optocoupler OC3 through relay RR1.

[0013] Furthermore, the control unit is also connected to a pressure sensor, a temperature sensor, and a vibration sensor; The pressure sensor is used to monitor the pressure of SF6 gas inside the gas chamber of electrical equipment; The temperature sensor is used to monitor the temperature of SF6 gas inside the gas chamber of electrical equipment; The vibration sensor is used to collect the vibration velocity of the gas density relay.

[0014] Furthermore, the present invention also proposes a control method for the gas density relay contact closure self-diagnostic device as described above, the method comprising: The control unit acquires the vibration speed of the gas density relay, and when it determines that the vibration speed exceeds the vibration threshold, it outputs a high level to the delay module, controls the output of the same-direction buffer G1 to be high level so that the electromagnet A3 is energized to generate magnetism and attract the dial pointer of the gas density relay. The control unit is configured to control the output of the inverse buffer G1 to be low when the voltage of resistor R8 in the delay module decreases to 1 / 2VCC, so that the electromagnet A3 is de-energized and the dial pointer of the gas density relay resumes indicating the gas density value. The control unit is used to delay the contact overpressure alarm signal triggered by the fault arc.

[0015] Furthermore, the method also includes: The control unit collects the voltage signal transmitted by the contact signal transmission module and determines the opening and closing state of the contact based on the voltage signal.

[0016] Furthermore, the method also includes: When the contact is closed, the control unit collects the pressure and temperature values ​​of the SF6 gas inside the gas chamber of the electrical equipment, and calculates the density value P. 20 ; The control unit will assign the density value P 20 The connection is compared with the set contact closure density value to verify whether the contact is working properly.

[0017] Furthermore, the method also includes: The control unit transmits the pressure value, the temperature value, and the density value P. 20 Upload to the backend server.

[0018] Furthermore, the control unit is configured to delay the contact overvoltage alarm signal triggered by a fault arc, including: When an overpressure alarm signal is received, the normally closed contact of the control relay RR1 closes, and the capacitor C2 is charged. When the voltage of capacitor C2 is 0, the output of the non-inverting buffer G1 is high, and the electromagnet A3 is energized to generate magnetism, which attracts the pointer of the dial.

[0019] The advantages of this invention are: (1) This invention achieves the function of delaying the alarm of overpressure caused by the arc of the gas chamber fault under the externally transmitted vibration state by setting a delay module, thereby improving the anti-interference ability of the density relay, enhancing the stability of the device, and improving the intelligent processing level of the density relay based on the diagnosis of the connection point; and since the light-emitting diode inside the optocoupler has unidirectional conductivity and severe nonlinearity, it is problematic to directly use the optocoupler to transmit signals. However, by placing the optocoupler in the feedback loop of the amplifier circuit, its nonlinearity can be overcome, realizing the isolated amplification and transmission of the connection signal, reducing the interference between the modules, and realizing real-time self-diagnosis of the connection point closure.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a gas density relay contact closure self-diagnostic device proposed in an embodiment of the present invention; Figure 2 This is a circuit structure diagram of the contact signal transmission module in an embodiment of the present invention; Figure 3 This is a circuit structure diagram of the delay module in an embodiment of the present invention; Figure 4 This is a schematic flowchart of a control method for a gas-sealed relay contact closure self-diagnostic device proposed in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1 to 3 As shown, an embodiment of the present invention proposes a gas density relay contact closure self-diagnostic device. The device includes: a control unit, a contact signal transmission module, and a contact module. The front end of the contact signal transmission module is connected to the contact module, and the rear end is connected to the control unit. The output of the control unit is connected to the delay module, and the contact module is connected to the contact interlock / alarm circuit. The contact signal transmission module includes optocoupler OC1 and optocoupler OC2, which are placed in the feedback loop of the amplifier circuit and the light-emitting diodes in optocoupler OC1 and optocoupler OC2 are connected in series. The delay module includes an optocoupler OC3, a relay RR1, a non-inverting buffer G1, and an electromagnet A3. The light-emitting diode in the optocoupler OC3 is connected to the output of the control unit. One end of the non-inverting buffer G1 and the electromagnet A3 connected in series is connected to the collector of the transistor in the optocoupler OC3 via the relay RR1, and the other end is connected to the emitter of the transistor in the optocoupler OC3.

[0024] Specifically, the contact module is structured as a micro switch, connected to the contact interlock / alarm circuit in the density relay. The control unit is used to monitor the closed state of the contact by transmitting the voltage signal through the contact signal transmission module. Since the light-emitting diode inside the optocoupler has unidirectional conductivity and severe nonlinearity, there are problems with directly using the optocoupler to transmit signals. In this embodiment, the optocoupler is placed in the feedback loop of the amplifier circuit, which can overcome its nonlinearity and realize isolated amplification and transmission of the contact signal, reduce interference between modules, and realize real-time self-diagnosis of contact closure.

[0025] When a circuit breaker is opened or closed, the density relay may be subjected to significant impact forces and vibrate. Under vibration, the mechanical structure within the density relay may experience substantial displacement. When the gas density value approaches the density value triggering contact locking or alarm, vibration may cause false triggering of the contact locking or alarm signal. This embodiment addresses this by incorporating a delay module. If the vibration velocity collected by the control unit exceeds a set vibration velocity threshold, the density relay is determined to be in a vibration state. At this time, the control unit outputs a high-level signal to the delay module, controlling the output of the unidirectional buffer G1 to be high, energizing the electromagnet A3 to generate magnetism and attract the dial pointer of the gas density relay, thus preventing false triggering.

[0026] In one embodiment, such as Figure 2 As shown, the feedback loop of the amplifier circuit includes operational amplifier A1 and operational amplifier A2; Operational amplifier A1 is connected between optocoupler OC1 and optocoupler OC2, and operational amplifier A2 is connected to the transistor in optocoupler OC1.

[0027] Furthermore, the positive input terminal of the operational amplifier A1 is connected to the collector of the transistor in the optocoupler OC2 via resistor R2 and positive power supply interface. The negative input terminal of the operational amplifier A1 is connected to the control unit via resistor R1. The output terminal of the operational amplifier A1 is connected to the positive terminal of the light-emitting diode in the optocoupler OC1 via resistor R3. The negative power supply interface of the operational amplifier A1 is connected to the emitter of the transistor in the optocoupler OC2. A capacitor C1 is connected between the negative input terminal and the output terminal of the operational amplifier A1.

[0028] The positive input terminal of operational amplifier A2 is connected to the positive power supply interface via resistor R4 and then connected to the collector of the transistor in optocoupler OC1. The negative power supply interface of operational amplifier A2 is connected to the emitter of the transistor in optocoupler OC1. Operational amplifier A2 is connected to the negative input terminal of operational amplifier A1 via resistor R5, and the negative input terminal of operational amplifier A2 is grounded via resistor R6.

[0029] It should be noted that the LEDs of the two optocouplers OC1 and OC2 are connected in series. Since OC1 and OC2 are perfectly matched, the current flowing through both LEDs is the same. Therefore, the transistors Uce in the two optocouplers are identical. Electrical isolation between the front-end and rear-end stages is achieved through the two optocouplers, while simultaneously amplifying the input signal from the front-end stage. The front-end stage connects to the contact module, and the rear-end stage connects to the control unit. The control unit determines the opening and closing state of the contacts by collecting the voltage from the contact signal transmission module. Simultaneously, it can also collect the density value P from pressure and temperature sensors when the contacts are closed. 20 The connection is compared with the set contact closure density value to verify whether the working status of the contact is normal, thus realizing the self-diagnosis of contact closure.

[0030] In one embodiment, such as Figure 3 As shown, diode D1 and resistor R9 are connected in series and then in parallel across the two ends of the non-inverting buffer G1. One end of the non-inverting buffer G1 is connected to resistor R8 and capacitor C2, respectively. The other end of the non-inverting buffer G1 is connected to electromagnet A3. Electromagnet A3 is connected to the emitter of the transistor in optocoupler OC3 after being connected to resistor R8. Capacitor C2 is connected to the collector of the transistor in optocoupler OC3 via relay RR1. The light-emitting diode in optocoupler OC3 is connected to the output terminal of the control unit via resistor R7.

[0031] It should be noted that the control unit outputs a signal to the optocoupler OC3. Under normal conditions, the control unit controls the optocoupler input voltage Ui to be 0, the normally closed contact of relay RR1 is open, capacitor C2 cannot be charged, and electromagnet A3 is not energized. Electromagnet A3 is located on the back of the density relay dial, close to the metal pointer but not in contact. When the gas density value vibrates near the closing point, the control unit collects data from the vibration sensor. If the vibration threshold is exceeded, the control unit controls the output level Ui to be high. The optocoupler transmits the signal, the normally closed contact of relay RR1 closes, and capacitor C2 is charged. Initially, the voltage of capacitor C2 is 0, the output of the non-inverting buffer G1 is high, and the energized electromagnet A3 generates magnetism, attracting the pointer of the dial to prevent false triggering of the contact signal. The charging voltage of capacitor C2 gradually increases, and the voltage of resistor R8 gradually decreases. When it reaches 1 / 2 VCC, the output of the non-inverting buffer G1 is low, the electromagnetic property of electromagnet A3 disappears, and the pointer indicates the original gas density value. By adjusting... Figure 3 The delay time is controlled by the values ​​of resistor R8 and capacitor C2. As long as the delay time is longer than the vibration time, false triggering caused by vibration can be avoided.

[0032] Specifically, in this embodiment, the delay module mainly consists of an optocoupler, a resistor, and a capacitor. It adopts a series RC structure and uses RC charging and discharging to control the voltage for delay, which allows for better and more precise control of the delay time. At the same time, the delay module uses an optocoupler to transmit control signals, which has stronger anti-interference capabilities.

[0033] Furthermore, considering that in actual operation, density relay contacts may experience false alarms or interlocking signals due to vibration. Simultaneously, electrical equipment operating in high-temperature, humid environments, or experiencing insulation aging or improper operation may generate fault arcs within the equipment. The high temperature generated by these fault arcs can cause a rapid increase in internal air pressure, triggering an overpressure alarm. Since the fault arc lasts only a short time, the overpressure alarm signal is deactivated once the internal air pressure returns to normal. If the control system fails to detect this fault arc in time, it poses a significant safety hazard. In this embodiment, when the control unit detects a fault arc inside the electrical equipment, it may trigger a contact overpressure alarm within a very short time. The control unit controls the delay module to delay the contact overpressure alarm signal, allowing the control system to promptly detect the alarm and then handle the fault arc, eliminating the safety hazard.

[0034] Specifically, the process by which the control unit controls the delay module to delay the overpressure alarm signal at the contact point is as follows: when an overpressure alarm occurs at the contact point, the control unit controls... Figure 3 U in i When the signal is high, the optocoupler transmits the signal, the normally closed contact of relay RR1 closes, and capacitor C2 is charged. Initially, the voltage of capacitor C2 is 0, the output of the non-inverting buffer G1 is high, the electromagnet A3 is energized and generates magnetism to attract the pointer of the dial, thus extending the duration of the overpressure alarm signal transmitted to the back-end.

[0035] In one embodiment, the control unit is further connected to a pressure sensor, a temperature sensor, and a vibration sensor; The pressure sensor is used to monitor the pressure of SF6 gas inside the gas chamber of electrical equipment; The temperature sensor is used to monitor the temperature of SF6 gas inside the gas chamber of electrical equipment; The vibration sensor is used to collect the vibration velocity of the gas density relay.

[0036] It should be noted that the control unit, contact signal transmission module, contact module, delay module, pressure sensor, temperature sensor, vibration sensor, communication module, power supply module, etc. can be installed inside the density relay or outside the density relay and connected to the density relay.

[0037] Pressure and temperature sensors monitor the SF6 gas pressure and temperature inside the gas chamber of the electrical equipment in real time. The control unit collects data from the pressure and temperature sensors at regular intervals and then converts it into the SF6 gas density value P at 20°C. 20 The gas density value is obtained to monitor the changes in gas density inside the gas chamber in real time. The communication module transmits the collected pressure value P, temperature value T, and calculated density value P. 20 Once the data is uploaded to the backend, communication can be via wired or wireless methods, such as RS485 bus or Wi-Fi. The power module supplies power to the various components of the density relay and can use a switching power supply, battery, or other similar devices. The vibration sensor is primarily used to monitor the vibration of the density relay.

[0038] Specifically, the control unit is mainly a microcontroller-based control circuit, including temperature acquisition circuit, pressure acquisition circuit, data acquisition circuit, power supply circuit, and communication circuit. It uses pressure and temperature sensors to monitor the SF6 gas pressure and temperature inside the gas chamber of the electrical equipment in real time. The control unit collects data from the pressure and temperature sensors at regular intervals and converts it into the SF6 gas density value P20 at 20°C. This density value is used to monitor changes in gas density inside the chamber in real time. The control unit compares the converted density value with the density value indicated by the pointer. If it is within a preset threshold, the gas density relay is considered to be in a normal operating state; otherwise, it is in an abnormal state. The communication module uploads the collected and calculated pressure value P, temperature value T, and density value P20 to the backend. This allows the backend to detect abnormal density data detected by the density relay. In the event of contact mis-triggering or overpressure alarm, the control unit can output a signal to the delay module, thereby delaying the transmission of the contact mis-triggering signal and extending the transmission time of the overpressure alarm signal.

[0039] In addition, such as Figure 4 As shown, another embodiment of the present invention proposes a control method for a gas density relay contact closure self-diagnostic device, the method comprising the following steps: S10. The control unit acquires the vibration speed of the gas density relay, and when it determines that the vibration speed exceeds the vibration threshold, it outputs a high level to the delay module, controls the output of the same-direction buffer G1 to be high level so that the electromagnet A3 is energized to generate magnetism and attract the dial pointer of the gas density relay. S20. The control unit is configured to control the output of the inverse buffer G1 to be low when the voltage of the resistor R8 in the delay module decreases to 1 / 2VCC, so that the electromagnet A3 is de-energized and the dial pointer of the gas density relay resumes indicating the gas density value. S30, the control unit is used to delay the contact overpressure alarm signal triggered by the fault arc.

[0040] In one embodiment, the method further includes: The control unit collects the voltage signal transmitted by the contact signal transmission module and determines the opening and closing state of the contact based on the voltage signal.

[0041] In one embodiment, the method further includes: When the contact is closed, the control unit collects the pressure and temperature values ​​of the SF6 gas inside the gas chamber of the electrical equipment, and calculates the density value P. 20 ; The control unit will assign the density value P 20 The connection is compared with the set contact closure density value to verify whether the contact is working properly.

[0042] In one embodiment, the method further includes: The control unit transmits the pressure value, the temperature value, and the density value P. 20 Upload to the backend server.

[0043] In one embodiment, step S30: The control unit is used to delay the contact overvoltage alarm signal triggered by the fault arc, specifically including the following steps: When an overpressure alarm signal is received, the normally closed contact of relay RR1 closes, and capacitor C2 is charged. When the voltage across capacitor C2 is 0 and the output of the non-inverting buffer G1 is high, the electromagnet A3 is energized and generates magnetism, attracting the pointer of the dial.

[0044] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A gas density relay contact closure self-diagnostic device, characterized in that, The device includes: a control unit, a contact signal transmission module, and a contact module. The front end of the contact signal transmission module is connected to the contact module, and the rear end is connected to the control unit. The output of the control unit is connected to a delay module, and the contact module is connected to a contact interlock / alarm circuit. The contact signal transmission module includes optocoupler OC1 and optocoupler OC2, which are placed in the feedback loop of the amplifier circuit and the light-emitting diodes in optocoupler OC1 and optocoupler OC2 are connected in series. The delay module includes an optocoupler OC3, a relay RR1, a non-inverting buffer G1, and an electromagnet A3. The light-emitting diode in the optocoupler OC3 is connected to the output of the control unit. One end of the non-inverting buffer G1 and the electromagnet A3 connected in series is connected to the collector of the transistor in the optocoupler OC3 via the relay RR1, and the other end is connected to the emitter of the transistor in the optocoupler OC3. Diode D1 and resistor R9 are connected in series and then in parallel across the two ends of the non-inverting buffer G1. One end of the non-inverting buffer G1 is connected to resistor R8 and capacitor C2, respectively. The other end of the non-inverting buffer G1 is connected to electromagnet A3. Electromagnet A3 is connected to the emitter of the transistor in optocoupler OC3 after being connected to resistor R8. Capacitor C2 is connected to the collector of the transistor in optocoupler OC3 via relay RR1. The light-emitting diode in optocoupler OC3 is connected to the output terminal of the control unit via resistor R7.

2. The gas density relay contact closure self-diagnostic device as described in claim 1, characterized in that, The feedback loop of the amplifier circuit includes operational amplifier A1 and operational amplifier A2; Operational amplifier A1 is connected between optocoupler OC1 and optocoupler OC2, and operational amplifier A2 is connected to the transistor in optocoupler OC1.

3. The gas density relay contact closure self-diagnostic device as described in claim 2, characterized in that, The positive input terminal of operational amplifier A1 is connected to the positive power supply interface and then to the collector of the transistor in optocoupler OC2. The negative input terminal of operational amplifier A1 is connected to the control unit. The output terminal of operational amplifier A1 is connected to the positive terminal of the light-emitting diode in optocoupler OC1 via a resistor. The negative power supply interface of operational amplifier A1 is connected to the emitter of the transistor in optocoupler OC2. The positive input terminal of operational amplifier A2 is connected to the positive power supply interface and then to the collector of the transistor in optocoupler OC1. The negative power supply interface of operational amplifier A2 is connected to the emitter of the transistor in optocoupler OC1.

4. The gas density relay contact closure self-diagnostic device as described in claim 1, characterized in that, The control unit is also connected to a pressure sensor, a temperature sensor, and a vibration sensor. The pressure sensor is used to monitor the pressure of SF6 gas inside the gas chamber of electrical equipment; The temperature sensor is used to monitor the temperature of SF6 gas inside the gas chamber of electrical equipment; The vibration sensor is used to collect the vibration velocity of the gas density relay.

5. A control method for a gas density relay contact closure self-diagnostic device as described in any one of claims 1 to 4, characterized in that, The method includes: The control unit acquires the vibration speed of the gas density relay, and when it determines that the vibration speed exceeds the vibration threshold, it outputs a high level to the delay module, controls the output of the same-direction buffer G1 to be high level so that the electromagnet A3 is energized to generate magnetism and attract the dial pointer of the gas density relay. The control unit is configured to control the output of the inverse buffer G1 to be low when the voltage of resistor R8 in the delay module decreases to 1 / 2VCC, so that the electromagnet A3 is de-energized and the dial pointer of the gas density relay resumes indicating the gas density value. The control unit is used to delay the contact overpressure alarm signal triggered by the fault arc.

6. The control method for the gas density relay contact closure self-diagnostic device as described in claim 5, characterized in that, The method further includes: The control unit collects the voltage signal transmitted by the contact signal transmission module and determines the opening and closing state of the contact based on the voltage signal.

7. The control method for the gas density relay contact closure self-diagnostic device as described in claim 5, characterized in that, The method further includes: When the contact is closed, the control unit collects the pressure and temperature values ​​of the SF6 gas inside the gas chamber of the electrical equipment, and calculates the density value P. 20 ; The control unit will assign the density value P 20 The connection is compared with the set contact closure density value to verify whether the contact is working properly.

8. The control method for the gas density relay contact closure self-diagnostic device as described in claim 7, characterized in that, The method further includes: The control unit transmits the pressure value, the temperature value, and the density value P. 20 Upload to the backend server.

9. The control method for the gas density relay contact closure self-diagnostic device as described in claim 5, characterized in that, The control unit is used to delay the contact overvoltage alarm signal triggered by the fault arc, including: When an overpressure alarm signal is received, the normally closed contact of the control relay RR1 closes, and the capacitor C2 is charged. When the voltage of capacitor C2 is 0, the output of the non-inverting buffer G1 is high, and the electromagnet A3 is energized to generate magnetism, which attracts the pointer of the dial.

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