A 10kv drop-out fuse automatic reset system

Abstract

This invention discloses an automatic reset system for a 10kV drop-out fuse, belonging to the field of power equipment technology. The system includes a detection module, a control module, a drive module, and a transmission mechanism. The control module executes a blocking judgment logic when the fuse is in the drop-out position. This blocking judgment logic includes determining whether the fuse is intact based on fuse integrity information, and outputting a reset control signal only when the fuse is intact and the preset automatic reset conditions are met. This invention, by adding a fuse integrity check before automatic reset, solves the safety hazard problem caused by blind automatic reclosing after fuse blown in existing technologies, significantly improving the safety and reliability of the automatic reset operation.

Description

Technical Field

[0001] This invention relates to the field of power system distribution equipment technology, specifically to an automatic reset system for a 10KV drop-out fuse. Background Technology

[0002] Drop-out fuses are a widely used overcurrent protection device in 10kV power distribution lines. When an overload or short-circuit fault occurs, the fuse wire melts, and the fuse tube automatically drops under its own weight and the action of the contact spring, forming a clear disconnection gap, thereby isolating the faulty section of the line. After the fault is cleared, maintenance personnel need to replace the fuse wire and push the fuse tube to the closed position to complete the reset.

[0003] With the development of power distribution network automation, electrically operated drop-out fuses are gradually being used. For example, Chinese patent CN121394264A discloses an electrically operated drop-out fuse and its control method, which realizes remote opening and closing operations through an intelligent control module and drive mechanism. Chinese patent CN121075881A discloses a controllable drop-out intelligent fuse that can achieve controlled drop-out based on measured current, temperature and other information.

[0004] However, existing automatic reset or remote closing schemes generally have a safety hazard: when a fuse has blown due to a fault, if the system automatically performs a closing operation, the fuse will close with the fault still attached, potentially causing equipment damage, arc burns, or even safety accidents. Although existing technologies can detect the fuse status, this detection information is usually only used for status indication (such as indicator lights) or to trigger active tripping (breaking the circuit), and is not incorporated into the safety verification logic of automatic reset.

[0005] In addition, although existing automatic reclosing devices (such as CN101855692A) are equipped with a fixed number of reclosing lockout mechanisms, they cannot distinguish between transient and permanent faults. They are prone to misjudging normal lines after transient faults are restored as permanent faults, or making ineffective reclosing attempts for permanent faults, resulting in cumulative damage to the equipment.

[0006] Therefore, there is an urgent need for an automatic reset system for 10KV drop-out fuses that can automatically identify the fault type and safely perform automatic reset provided the fuse is intact. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic reset system for a 10KV drop-out fuse, so as to solve the technical problems of existing automatic reset systems lacking fuse integrity verification and being unable to distinguish fault types, which leads to safety hazards and equipment damage.

[0008] This invention provides an automatic reset system for a 10kV drop-out fuse, comprising: The detection module is used to detect the drop-out status of the drop-out fuse in real time. The control module, electrically connected to the detection module, is used to receive the drop status and output a reset control signal; The drive module, electrically connected to the control module, is used to receive the reset control signal and output driving force. The transmission mechanism is mechanically connected to the drive module and, under the action of the driving force, drives the fallen fuse tube to perform a reset action; Specifically, the control module is used to execute a lockout judgment logic when the drop state indicates that the fuse is in a drop position; the lockout judgment logic includes judging whether the fuse is intact based on the fuse integrity information obtained by the detection module, and if the fuse is intact and meets the preset automatic reset conditions, then outputting the reset control signal.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Significantly improved safety: This invention uses the integrity of the fuse as a prerequisite for automatic reset. Automatic reset is only allowed when the fuse is intact, which completely avoids safety accidents caused by blindly closing the circuit after the fuse blows and fills the gap in this safety verification process in the existing technology.

[0010] 2. Adaptive Fault Type Handling: By setting up a fault type identification unit, transient and permanent faults are automatically distinguished based on current change characteristics and drop trigger time characteristics, and different control strategies are adopted. For transient faults, automatic reset to restore power supply is allowed; for permanent faults, automatic reset is prohibited and an alarm is issued, reducing unnecessary operations and impact on equipment.

[0011] 3. Intelligent linkage between reset count and fault type: The reset count counter is linked with the fault type identification result. The counter is reset after a successful reset of a transient fault, while the counter is directly stopped and locked for a permanent fault. This achieves rapid isolation of permanent faults and avoids the damage caused by repeated attempts in the traditional fixed-number reclosing mode.

[0012] 4. Closed-loop precise control: During the reset process, the fuse position is compared with the pre-stored reference position in real time, and the system stops when the fuse is in position, avoiding overshoot or undershoot. After reset, the system performs dual verification through contact resistance value and continuity detection to ensure the quality of closing and improve the reliability of reset. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the structure of an automatic reset system for a 10KV drop-out fuse according to an embodiment of the present invention. Detailed Implementation

[0015] 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 with reference to the accompanying drawings. 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.

[0016] like Figure 1 As shown, the present invention provides an automatic reset system for a 10KV drop-out fuse, comprising: a detection module, a control module, a drive module, and a transmission mechanism.

[0017] The detection module is used to detect the drop-out state of the drop-out fuse in real time; the control module is electrically connected to the detection module and is used to receive the drop-out state and output a reset control signal; the drive module is electrically connected to the control module and is used to receive the reset control signal and output a driving force; the transmission mechanism is mechanically connected to the drive module and, under the action of the driving force, drives the drop-out fuse tube to perform a reset action; specifically, the control module is used to execute a lockout judgment logic when the drop-out state indicates that the fuse tube is in the drop-out position; the lockout judgment logic includes judging whether the fuse is intact based on the fuse integrity information obtained by the detection module; if the fuse is intact and meets the preset automatic reset conditions, a reset control signal is output.

[0018] Specifically, the detection module is responsible for sensing the status of the drop-out fuse. Its core function is "real-time detection of the drop-out status," that is, determining whether the fuse tube has fallen from the closed position to the drop-out position. The detection module can be implemented using various sensors, such as limit switches, Hall effect proximity switches, photoelectric switches, etc., installed at the end of the fuse tube's drop travel. When the fuse tube falls to the correct position, the sensor outputs an electrical signal (such as a transition from a high level to a low level). In this embodiment, the "detection module" is not limited to drop-out status detection; it can also integrate other detection functions (such as current detection, fuse status detection, etc.).

[0019] The control module is electrically connected to the detection module and receives the drop status signal from the detection module. After internal logic judgment, it decides whether to output a reset control signal. The "execution of interlocking judgment logic" in this embodiment is not simply "outputting a reset signal upon detecting a drop," but includes a prerequisite: determining whether the fuse is intact based on the fuse integrity information obtained by the detection module. This means that before deciding whether to reset, the control module must actively acquire the fuse's status information (e.g., detecting whether the fuse is in place via a microswitch, or detecting whether the fuse is continuous via a photoelectric sensor), and only when the fuse is in an intact state is it allowed to proceed to the next judgment step. If the fuse has blown, even if other conditions are met, the control module will not output a reset signal, thus avoiding safety accidents caused by blindly closing the circuit breaker when the fuse is blown.

[0020] The preset automatic reset conditions may include, but are not limited to, the line current dropping below a safety threshold, or the fuse drop duration exceeding a set delay. This embodiment addresses the safety blind spot that was not considered in all existing automatic closing schemes by making "fuse intact" a mandatory prerequisite for automatic reset.

[0021] The drive module is electrically connected to the control module, receiving reset control signals (such as PWM pulses or relay contact signals) output by the control module and converting these electrical signals into mechanical energy (driving force). The drive module can be a DC motor, AC motor, electromagnet, electromagnetic repulsion mechanism, pneumatic or hydraulic actuator, etc. Its core function is to provide sufficient force to overcome the gravity of the fuse tube and the resistance of the contact spring, pushing the fuse tube from the drop position back to the stop position.

[0022] The transmission mechanism is mechanically connected to the drive module and serves as the force transmission intermediary between the drive module and the fusible tube. The rotary or linear motion output by the drive module is converted into a motion suitable for pushing the fusible tube through the transmission mechanism. Common forms include: gear-rack mechanisms (converting the motor's rotary motion into linear motion), crank-connecting rod mechanisms, push-pull rod assemblies, brackets, etc. The transmission mechanism may also include guiding structures (such as guide rails and slides) and positioning structures (such as tube clamp grooves) to ensure that the fusible tube moves along a predetermined trajectory and ultimately reaches the closing position accurately.

[0023] In one optional implementation, the preset automatic reset condition includes at least one of the following: determining whether the line current is lower than a preset safety threshold, and determining whether the duration of the fuse tube in the drop position exceeds a preset delay threshold.

[0024] Specifically, "determining whether the line current is below the preset safety threshold" means that after the fuse falls, the control module continuously monitors the line current through a detection module (such as a current transformer). If the line current is still higher than a certain preset safety threshold (e.g., 5A or 10% of the rated current), it indicates that the fault has not been completely cleared. At this time, even if the fuse is intact, the circuit should not be closed, otherwise it may cause a re-fault. When the current drops below the safety threshold, it indicates that the fault has disappeared or has been isolated by other switching equipment, allowing for automatic reset. This threshold can be flexibly set according to line parameters and protection coordination requirements.

[0025] "Determining whether the duration of the fuse tube in the drop position exceeds the preset delay threshold" refers to the fact that at the instant the fuse tube just drops, a transient disturbance (such as a flashover caused by lightning overvoltage) may cause the fuse to malfunction, but the fault itself is transient. If reset immediately, the circuit breaker may be closed before the arc is extinguished or the fault is completely eliminated. Therefore, a delay threshold (e.g., 0.5 seconds, 2 seconds, or 5 seconds) is set, requiring the fuse tube to remain in the drop position for more than this threshold before considering the fault truly cleared or the line stable, and then performing a reset. This delay can avoid false resets caused by transient processes.

[0026] In one optional implementation, the control module further includes a fault type identification unit; the fault type identification unit classifies the current fault as a transient fault or a permanent fault based on the current change characteristics and drop trigger time characteristics obtained by the detection module; if classified as a permanent fault, the control module prohibits the output of a reset control signal and outputs a fault alarm signal.

[0027] In this embodiment, the fault type identification unit can be an independent hardware module or a software algorithm or logic function within the control module. Its core function is to automatically identify the essential attributes of the fault from the electrical and mechanical characteristics during the fault occurrence process.

[0028] Specifically, the current change characteristics refer to the fault current waveform collected by the fault type identification unit analysis and detection module (current transformer). The current waveform of transient faults (such as flashover caused by lightning strikes or momentary contact between a tree branch and a wire) typically exhibits the following characteristics: the amplitude initially rises sharply, then rapidly decays and oscillates, with a short duration (generally less than 3-5 power frequency cycles), after which the current returns to normal or drops to zero. The current waveform of permanent faults (such as broken wires or internal short circuits in transformers) exhibits the following characteristics: the amplitude is stable and continuously increases until the fuse blows or the upstream switch trips; the waveform is usually a flat rectangle with no significant attenuation.

[0029] The drop trigger time characteristic refers to the time interval Δ between the occurrence of a fault (current exceeding the set value) and the fuse blowing and triggering the drop detection signal. t For different fault types, Δt There are significant differences: transient faults (especially lightning overvoltage) often involve large current surges, causing fuses to blow rapidly, Δ t Very short (e.g., less than 10ms); permanent faults (such as slow fuse failure due to overload) may Δ t The time frame can be quite long (up to hundreds of milliseconds or even seconds). Setting multiple time thresholds can help in making this judgment.

[0030] If a transient fault is identified, the system allows the automatic reset process to continue (provided that the fuse is intact and the preset automatic reset conditions are met).

[0031] If a permanent fault is identified: the control module immediately disables the output of the reset control signal, meaning it will no longer attempt to reset automatically. Simultaneously, it outputs a fault alarm signal (e.g., by uploading it to the monitoring center via the communication module, illuminating a local alarm indicator, or activating a buzzer) to remind maintenance personnel that the fault requires manual handling and that a reset can only be performed after replacing the fuse or repairing the wiring.

[0032] In summary, for permanent faults, the system will "actively abort" automatic reset to avoid repeated impact damage to the fuse body, transmission mechanism, and line equipment caused by multiple ineffective closing operations, while reducing unnecessary energy waste and safety hazards. For transient faults, power supply is quickly restored, improving power supply reliability.

[0033] In one alternative implementation, the control module further includes a reset count counter.

[0034] The reset count counter is used to accumulate the number of automatic resets of the same fuse tube after the same fault event. When the number of automatic resets reaches the preset upper limit, the control module prohibits the output of the reset control signal and outputs an alarm signal. The fault classification result of the fault type identification unit is used to reset or maintain the counting state of the reset count counter: if it is classified as a transient fault, the reset count counter is reset; if it is classified as a permanent fault, the counting is terminated and a permanent fault alarm signal is output.

[0035] Specifically, in this embodiment, the reset count counter and the fault type identification result are linked with the counter's status management to form an intelligent closed-loop control strategy.

[0036] The reset count counter is an internal counter (which can be a software variable or a dedicated register) maintained by the control module to record the number of times the same fuse undergoes automatic reset after the occurrence of the "same fault event." Here, the "same fault event" refers to the time period from the first detected fuse drop to the point where the system determines that the fault has been completely cleared or is now permanent. After each successful automatic reset attempt, if the fault recurs (i.e., the fuse drops again), whether the counter increments depends on whether the fault belongs to the same event—usually determined by a time window. For example, if a second drop occurs within 30 seconds of the first drop, it is considered a subsequent action of the same event, and the counter increments; if the time window is exceeded, it is considered a new event, and the counter is reset.

[0037] The preset maximum number of attempts refers to the maximum number of automatic reset attempts allowed by the system. This can be set based on factors such as line importance, fuse mechanical life, and protection coordination requirements; typical values ​​are 1, 2, or 3 attempts. When the cumulative number of attempts reaches this limit, the control module will prohibit the output of any subsequent reset control signals and will output an alarm signal, requiring manual intervention. This is to prevent the system from repeatedly resetting without limit under persistent fault conditions, which could cause equipment wear and safety hazards.

[0038] If the fault is classified as transient, it indicates that the fault is temporary, and the line will likely return to normal after a successful automatic reset. In this case, the control module resets (clears) the reset count counter to allow for a new count for the next possible independent fault event. For example, if a lightning strike causes a fuse to trip, the system automatically resets successfully on the first attempt, the counter changes from 0 to 1, and then immediately resets to 0; if another lightning strike occurs 10 minutes later, the system restarts the count from 0. This ensures that each independent transient fault receives a full set of reset attempts.

[0039] If the fault is classified as permanent, it indicates that the fault is a permanent damage to the equipment or line, and any automatic reset attempt will be ineffective. In this case, the control module stops counting (i.e., it no longer increments or resets) and directly outputs a permanent fault alarm signal. A better implementation is: once a permanent fault is identified, the counter is directly set to a preset maximum number of attempts (or a special flag), so that the control module will never attempt an automatic reset again until a manual field reset operation clears the flag.

[0040] The reset count limit + fault type linkage mechanism of this invention is more intelligent than the traditional "fixed number of reclosing re-locking and permanent blocking" because it can distinguish between "continuously occurring instantaneous faults" (such as multiple flashovers caused by lightning strikes, where the fault does not completely disappear after the first successful reset and occurs again, in which case the counter should not be reset) and "instantaneous faults of different events" (the counter should be reset). This achieves differentiated handling of instantaneous faults and permanent faults, ensuring that the system has enough recovery attempts under instantaneous faults and avoiding invalid impacts under permanent faults. At the same time, intelligent counting management reduces the unnecessary deployment of maintenance personnel.

[0041] In one optional implementation, the control module is further configured to acquire the fuse tube movement position information fed back by the detection module in real time during the process of the transmission mechanism driving the fuse tube to perform the reset action, and compare the fuse tube movement position information with the pre-stored closing reference position in real time; when the comparison result shows that the fuse tube has reached the closing position, a stop signal is output to make the drive module stop outputting driving force.

[0042] Specifically, the pre-stored closing reference position refers to the "position self-learning" required after the system's initial installation or maintenance. The specific operation can be as follows: manually push the fuse to the accurate closing position, then press the "learn" button on the control module. The control module records the position signal fed back by the current detection module (e.g., the distance value of the laser displacement sensor, the trigger threshold of the Hall switch, the number of encoder pulses, etc.) and stores it as the closing reference position in non-volatile memory (such as EEPROM or Flash). This reference position represents the mechanical position where the fuse and the stationary contact achieve optimal electrical contact.

[0043] Real-time position information acquisition refers to the process during the reset operation where the detection module (such as a position sensor, displacement sensor, encoder, etc.) continuously feeds back the current movement position of the fuse tube at a high frequency (e.g., 100Hz to 1kHz). The control module continuously reads this data.

[0044] Real-time comparison refers to the control module comparing the real-time position value with the pre-stored closing reference position. Several comparison methods can be used: Absolute position comparison: When the real-time position is equal to or greater than the reference position, it is considered that the location has been reached.

[0045] Relative threshold comparison: When the difference between the real-time position and the reference position is less than the set error (e.g., ±0.5mm), it is considered that the target is about to be reached.

[0046] Speed-position joint judgment: When approaching the reference position, the speed is used to determine whether deceleration or braking is required.

[0047] The output stop signal refers to the control module immediately outputting a stop signal to the drive module once the comparison result shows that the fuse has reached (or is about to reach) the closing reference position. For motor drives, the stop signal can be cutting off the power supply, applying reverse braking, or connecting a braking resistor; for electromagnetic drives, the stop signal can be cutting off the discharge circuit or engaging the dynamic braking circuit.

[0048] In summary, the closed-loop control method in this embodiment can avoid two problems: 1. Overshoot: If the drive module continues to output power after the fuse tube reaches the closing position, the fuse tube may overshoot the closing position, impact the stationary contact or other components, causing mechanical damage or failure to close properly.

[0049] 2. Under-travel: If the drive module stops too early and the fuse tube does not fully reach the closing position, it may cause poor contact of the contacts, excessive contact resistance, and cause overheating or even burnout.

[0050] Compared with the "open-loop control" commonly found in the prior art (which stops after a given fixed time or fixed stroke), the position feedback closed-loop control in this embodiment can adapt to different working conditions (such as changes in the frictional resistance of the molten tube, temperature effects, mechanical wear, etc.) to ensure that each reset is accurate.

[0051] In one optional implementation, the control module is further configured to: after the fuse tube is reset to the closed position, determine whether the contact state between the fuse tube and the stationary contact reaches a preset tightness based on the contact resistance value fed back by the detection module, and determine whether the line is conductive based on the line continuity detection signal; if the contact state does not reach the preset tightness or the line is not conductive, output a fault alarm signal and prohibit subsequent automatic reset operations.

[0052] This embodiment adds a dual quality verification mechanism after the reset is completed, based on the "stop in position" principle, to ensure that the closing position is not only correct mechanically, but also that the electrical contact is good and the line is truly energized.

[0053] Specifically, methods for measuring contact resistance include, but are not limited to: the control module activating the contact resistance measurement circuit after the fuse reaches the closed position and the drive module stops. A common method is the "four-wire Kelvin connection," which involves applying a constant, weak DC current (e.g., 1A to 10A, for a very short duration, such as 10ms, to avoid overheating) between the fuse and the stationary contact, while simultaneously using a high-precision voltage measurement circuit to detect the voltage drop across the contact, and calculating the contact resistance based on Ohm's law. This measurement circuit can be integrated into the control module and automatically disconnects after the measurement is completed.

[0054] The preset tightness refers to a preset contact resistance threshold. For example, for a 10kV, 100A rated current drop-out fuse, the contact resistance during normal closing should be less than 100μΩ. If the measured contact resistance is greater than this threshold (e.g., exceeding 200μΩ), it indicates that there is an oxide layer, foreign matter, or insufficient pressure between the fuse tube and the stationary contact, which is a "false closing" or poor contact condition. Long-term operation will result in severe overheating or even burn out the fuse.

[0055] Judgment logic: If the contact resistance is less than or equal to the preset threshold, the contact is considered good; otherwise, the preset tightness is not achieved.

[0056] Methods for measuring line continuity detection signals include, but are not limited to, determining whether the line is truly continuous by detecting whether there is current on the secondary side of a current transformer. However, at the moment of reset, the line may not yet be energized (e.g., the upstream switch is still in the open state), thus requiring a more precise judgment. One method is for the control module to use a signal injection circuit (e.g., injecting a high-frequency, low-amplitude signal into the line) and detect whether the signal can form a loop through the fuse; another method is to wait for a period of time (e.g., 1 second) and then detect whether there is voltage or a weak capacitive current in the line. A simpler method is to directly read the voltage signal if there is a voltage transformer on the line side; otherwise, it can be determined by detecting whether a voltage difference is established across the fuse.

[0057] "Conduction status" refers to the condition where a normal voltage or current (greater than the lower limit of the safety threshold) is detected in the line, indicating that the line is conducting. If there is no electrical signal at all, it may be due to an upstream switch not being closed or a line being broken. In this case, even if the fuse is closed, power will not be supplied to the user, but the fuse itself is not faulty, so subsequent operations are not necessarily prohibited. In this embodiment, "not conducting" specifically refers to the condition where conduction should occur (e.g., the upstream switch is known to be closed) but no conduction signal is detected, or an abnormal open circuit state is detected.

[0058] If the contact resistance does not reach the preset tightness or the circuit is not conductive (when it should be conductive), the control module outputs a fault alarm signal (local audible and visual alarm + remote communication alarm).

[0059] Meanwhile, the control module prohibits subsequent automatic reset operations. This is to prevent the system from repeatedly attempting to reset the same faulty contact state, avoiding mechanical wear and electrical burn-out. Subsequent handling can only be done through manual on-site intervention (such as readjusting the installation position, cleaning the contacts, replacing the fuse, etc.), and the lockout can be released through the manual operation interface.

[0060] In one optional embodiment, the system of the present invention further includes a communication module; The communication module is electrically connected to the control module and is used to establish two-way communication with the remote monitoring center to receive remote reset commands and / or upload drop status.

[0061] The communication module can be any type of wireless or wired communication unit, such as a 4G / 5G module, NB-IoT module, LoRa module, Wi-Fi module, Ethernet interface, RS485 bus, etc. The communication module and control module are connected via standard interfaces such as UART, SPI, and CAN.

[0062] The two-way communication function includes upload and receive functions. The upload function specifically includes the control module actively or passively sending real-time system status data to the remote monitoring center. Uploaded data includes, but is not limited to: fuse drop status (dropped / closed), fuse integrity information (intact / blown), line current value, fault type identification result (instantaneous / permanent), automatic reset count, alarm information (poor contact, permanent fault, etc.), and equipment self-diagnostic information. This data helps maintenance personnel remotely understand the field situation, predict faults, and schedule operations. The receive function specifically includes the control module receiving instructions from the remote monitoring center. The most important type of instruction is the "remote reset instruction." When analysts at the remote monitoring center deem the conditions met, they can issue a reset instruction to the field control module. Upon receiving this instruction, the control module will not execute it immediately but will treat it as a form of "manual reset," still requiring verification by local interlocking logic (i.e., fuse integrity judgment, current and delay conditions, fault type judgment, etc.). Only when all local interlocking conditions are met will the control module execute the reset operation. This design ensures that remote commands do not bypass security checks, which is in line with the power system principle that "remote operation must be combined with local security logic".

[0063] In summary, by introducing a communication module, the system of this invention can be seamlessly integrated into existing distribution network automation systems, enabling functions such as remote monitoring, remote control, fault early warning, and data recording and analysis, thereby reducing operation and maintenance costs and improving fault response speed.

[0064] In one optional embodiment, the system of the present invention further includes a manual operation interface; The manual operation interface is electrically connected to the control module and is used to receive manual reset commands from the field; the control module is also used to prioritize responding to manual reset commands from the field.

[0065] Specifically, the manual operation interface can take many forms: physical buttons (set on the fuse body or nearby control box, such as a "manual reset" button), infrared remote control receiver (maintenance personnel use a handheld infrared remote control to send reset commands), Bluetooth or near-field communication module (connected via a mobile APP), and insulated operating rod contacts (a signal is triggered by touching the metal contacts with a dedicated insulated rod).

[0066] The on-site manual reset command refers to the command that can be triggered when maintenance personnel arrive at the site. Typically, after troubleshooting, replacing fuses, or repairing lines, maintenance personnel need to manually close the fuse. The automatic reset system of this invention does not exclude manual operation but provides a manual interface as a supplement.

[0067] Priority response means that the control module, during any automatic reset logic execution, will immediately pause or interrupt the current automatic reset process and execute the manual reset command upon detecting a manual reset command (e.g., a button being pressed or an infrared signal being received). This means that even if the system is in a "waiting delay" phase, a manual command can immediately trigger a reset. The execution result of the manual command should be recorded and uploaded.

[0068] The present invention's embodiment prioritizes response to manual commands, ensuring that on-site maintenance personnel have the highest control over the equipment, which is a fundamental requirement of power safety operating procedures. Simultaneously, the existence of a manual operation interface allows for fuse operation even in the event of communication failures or automatic logic malfunctions, improving system availability and security.

[0069] In one optional implementation, the detection module further includes a fuse status detection unit; The fuse status detection unit is a mechanical microswitch or photoelectric sensor used to directly detect the physical continuity of the fuse.

[0070] Specifically, the working principle of a mechanical micro switch is as follows: A movable contact is installed at one end of a fuse. When the fuse is intact and under tension, the tension of the fuse presses the contact into a fixed position, depressing the micro switch contact and outputting an electrical signal (such as a high level). When the fuse melts, the tension disappears, the contact returns to its original position under the action of a spring, and the micro switch contact springs back up, outputting an opposite electrical signal (such as a low level). The advantages of this detection method are: simplicity and reliability, unaffected by ambient temperature and humidity, and direct reflection of the mechanical continuity of the fuse.

[0071] Photoelectric sensors can be either through-beam or reflective. Through-beam type: A light-emitting diode (LED) and a photosensitive receiver are mounted on opposite sides of a fuse, with the fuse passing through the optical path. When the fuse is intact, it blocks the light, and the receiver outputs a low level (or no signal); when the fuse melts, the optical path is unobstructed, the receiver receives the light, and outputs a high level. Reflective type: The light-emitting and receiving components are on the same side; the fuse surface reflects the light, and the reflection disappears after the fuse melts. The advantages of photoelectric sensors are: non-contact, no mechanical wear, and fast response speed.

[0072] The automatic reset system for a 10kV drop-out fuse of the present invention includes the following steps in its overall automatic reset control method: Step S1: Real-time detection of the drop-out status of the drop-out fuse.

[0073] The control module reads the output signal of the position sensor in the detection module at a fixed period (e.g., 10ms). When the position sensor signal changes from the "closed position" state to the "drop position" state, the control module records the timestamp of the drop and confirms that the fuse tube is in the drop position.

[0074] Step S2: Obtain fuse integrity information and determine whether the fuse is intact.

[0075] The control module reads the output signal from the fuse status detection unit (mechanical microswitch or photoelectric sensor). If the signal indicates that the fuse is intact (e.g., the microswitch is pressed down and outputs a high level, or the photoelectric sensor's optical path is blocked and outputs a low level), then proceed to step S3; if the signal indicates that the fuse has blown (e.g., the microswitch pops up and outputs a low level, or the photoelectric sensor's optical path is unobstructed and outputs a high level), then the control module immediately outputs a "fuse blown" alarm signal and prohibits all subsequent automatic reset operations, and the process terminates.

[0076] Step S3: Execute the additional judgment item in the interlock judgment logic. If the preset automatic reset condition is met, a reset control signal is generated.

[0077] Assuming the fuse is intact, the control module performs the following additional checks sequentially (or in parallel): Line current judgment: Read the current value of the current detection unit (current transformer). If the line current is higher than the preset safety threshold (e.g., 5A), it means that the fault has not been cleared, so continue to wait and repeat the detection; if the line current is lower than the safety threshold, it is considered that the fault has disappeared.

[0078] Fall duration determination: Calculate the time difference between the current time and the fall time recorded in step S1. If the time difference is less than a preset delay threshold (e.g., 2 seconds), continue waiting; if it exceeds the delay threshold, the line is considered stable.

[0079] Fault type identification: If the system is equipped with a fault type identification unit, it determines whether the current fault is transient or permanent based on the fault current waveform characteristics and drop trigger time characteristics. If it is determined to be a permanent fault, the reset control signal is directly disabled, a permanent fault alarm is output, and the process terminates; if it is determined to be a transient fault, it is allowed to continue.

[0080] Reset Count Check: If the system is configured with a reset count counter, check whether the cumulative number of automatic resets within the same fault event has reached the preset upper limit (e.g., 2 times). If the upper limit has been reached, the reset control signal will be disabled and an alarm will be output, and the process will terminate; if the upper limit has not been reached, the process will continue.

[0081] When all the additional judgment items configured above meet the conditions, the control module generates a reset control signal (e.g., outputting a high-level pulse or sending a CAN message).

[0082] Step S4: Drive the drive module according to the reset control signal, and drive the fallen fuse tube to perform a reset action through the transmission mechanism, so that the fuse tube returns to the closed position.

[0083] The control module sends a reset control signal to the drive module. The drive module outputs the corresponding mechanical driving force (e.g., forward rotation of a DC motor, discharge of an electromagnetic repulsion mechanism, etc.) according to the signal type, and pushes the fusible tube upward through the transmission mechanism (gear-rack, push-pull rod, bracket, etc.).

[0084] During the reset process, the control module acquires the fuse tube's position information (such as Hall switch, laser displacement sensor, or encoder signal) from the detection module in real time and compares it with the pre-stored closing reference position. When the fuse tube reaches the closing position, the control module immediately outputs a stop signal, causing the drive module to stop outputting driving force to avoid overshoot or undershoot.

[0085] After the reset action is completed, the control module performs a dual verification: First, it uses a contact resistance measurement circuit to detect the contact resistance between the fuse and the stationary contact to determine if it meets the preset tightness requirement (e.g., contact resistance ≤ 100μΩ); second, it uses a line continuity detection signal (current, voltage, or injected signal) to determine if the line is truly conductive. If both verifications pass, the system returns to normal monitoring status; if either fails, a fault alarm signal is output, and subsequent automatic reset operations are prohibited, awaiting manual intervention.

[0086] Throughout the entire operation process, the on-site manual reset command has the highest priority. Regardless of the system's current state, once an on-site manual reset command is detected (e.g., pressing a manual button or using infrared remote control), the control module immediately interrupts the current automatic process and executes the manual reset command (but still requires a fuse integrity check). Remote reset commands, on the other hand, must undergo local interlocking logic verification before execution.

[0087] Example 1 A 10kV rural power distribution line has multiple sets of drop-out fuses distributed along its length. This line is frequently affected by transient faults such as lightning strikes and tree branch contact with the wire, as well as permanent faults caused by line aging and user equipment malfunctions. Maintenance personnel aim to achieve automatic power restoration after transient faults without increasing the frequency of on-site inspections, while also avoiding repeated impacts from permanent faults.

[0088] 1. Hardware configuration: Fuse status detection unit: Miniature limit switch (mechanical micro switch), mounted on an insulating bracket, with its contact linked to one end of the fuse. When the fuse is intact and taut, the switch is pressed down and outputs a high level; after the fuse melts and the tension disappears, the switch resets and outputs a low level.

[0089] Position sensor: Hall effect proximity switch, installed at the end of the fuse tube's drop stroke, used to detect whether the fuse tube has completely dropped.

[0090] Current detection unit: current transformer, installed on the incoming side of the fuse.

[0091] Control module: STM32F103 microcontroller with built-in EEPROM to store closing reference position and threshold parameters.

[0092] Drive module: DC geared motor, connected to the bracket at the bottom of the molten tube via a gear-rack transmission mechanism. The bracket is equipped with a tube clamp groove that matches the retaining ring in the middle of the molten tube.

[0093] Communication module: 4G module, used for two-way communication with the monitoring center.

[0094] 2. The specific operating procedures include: S1: The control module reads the Hall proximity switch signal at a 10ms cycle. When a short circuit fault occurs in the line, the fuse blows, the fuse tube falls and triggers the Hall switch, and the control module records the time of the fall.

[0095] S2: The control module reads the limit switch signal. If it is low (fuse blown), it directly outputs an alarm "Fuse blown, please replace" and uploads it via 4G, disabling automatic reset and terminating the process. If it is high (fuse intact), it proceeds to S3.

[0096] S3: Line current judgment: Read the current transformer. If the current is still higher than 5A (safety threshold), wait for a delay; if it is lower than 5A, continue.

[0097] Fall duration determination: Calculate the fall duration. If it is less than 2 seconds (delay threshold), continue waiting; if it exceeds 2 seconds, continue.

[0098] Fault type identification: Fault type is identified based on the time difference Δt between the sudden current change and the limit switch action, and the characteristics of the fault current waveform. If Δt < 10ms and the fault current decays rapidly, it is determined to be a transient fault; otherwise, it is determined to be a permanent fault. If it is a permanent fault, reset is prohibited, an alarm is output, and the process terminates.

[0099] Reset count check: The reset count counter accumulates the number of resets within the same fault event. If the upper limit has been reached (e.g., 2 times), reset is prohibited and an alarm is triggered; if the upper limit has not been reached and the fault is transient, reset is allowed and the counter is incremented by 1.

[0100] When all conditions are met, the control module generates a reset control signal (PWM pulse).

[0101] S4: The drive motor rotates forward, pushing the molten tube upward through the gear-rack and bracket.

[0102] Real-time position comparison: The Hall switch is also triggered when the circuit is closed, and the control module compares the real-time position with the pre-stored closing reference position. The motor stops immediately upon reaching the reference position.

[0103] Double verification after reset: Measure the contact resistance. If it is ≤100μΩ and the line current returns to normal (>1A), the reset is successful and the counter is cleared; otherwise, output an alarm and prohibit subsequent automatic reset.

[0104] Manual Reset Priority: On-site maintenance personnel can send a manual reset command via a handheld infrared remote control. The control module will immediately interrupt the automatic process and prioritize the execution of the manual command (but will still check the integrity of the fuse).

[0105] Example 2 A 10kV cable-overhead hybrid power line in a certain city has a high load density and extremely high requirements for power supply reliability. The line is already equipped with a feeder automation (FA) system, and it is necessary to implement an intelligent reset function linked to the feeder automation system at the drop-out fuses of the branch lines.

[0106] 1. Hardware configuration: Fuse status detection unit: Through-beam photoelectric sensor, with the fuse passing through the optical path. When the fuse is intact, it blocks the light, and the receiving tube outputs a low level; when it blows, the optical path is unobstructed, and the output is a high level.

[0107] Position sensor: Laser displacement sensor, installed near the contact on the fusible tube, with a measurement accuracy of 0.1mm, can be used for both drop detection and real-time position feedback.

[0108] Current detection unit: Rogowski coil, high bandwidth, used to capture transient characteristics of fault current.

[0109] Control module: Industrial-grade ARM processor (i.MX RT series), supports IEEE1588 time synchronization, and has a built-in fault feature library.

[0110] Drive module: Electromagnetic repulsion mechanism + energy storage capacitor (400V capacitor bank). The capacitor charges during normal power supply; during reset, the control thyristor discharges, generating electromagnetic repulsion to push the push rod to eject the fuse tube back to its original position. It is also equipped with a buffer damper and dynamic braking circuit.

[0111] Communication module: IEC61850 GOOSE protocol Ethernet interface, for interaction with the FA master station.

[0112] Manual operation interface: two waterproof buttons (green reset enable button, red emergency lock button).

[0113] 2. The specific operating procedures include: S1: The laser displacement sensor monitors the distance between the fuse tube and the stationary contact in real time. When the distance suddenly exceeds the threshold (e.g., from 2mm when closing to 150mm when falling), the control module records the fall event and uploads it to the FA master station via GOOSE.

[0114] S2: Read the output of the photoelectric sensor. If it is high (fuse blown), report "Fuse blown, needs replacement", illuminate the local red indicator light, disable reset, and terminate the process. If it is low (intact), proceed to S3.

[0115] S3: Line current judgment: The Rogowski coil samples the fault current waveform. If the current amplitude is still higher than the safety threshold (which can be dynamically set), wait for the FA master station command.

[0116] Drop duration determination: Calculate the drop duration and continue after it exceeds the preset delay (e.g., 500ms).

[0117] Fault type identification: The control module records the waveforms before and after the fault at a sampling rate of 200kHz, extracts features through wavelet transform, and distinguishes between transient faults (high-frequency oscillation decay) and permanent faults (flat and continuous). The identification results are compared with the instructions issued by the FA master station. If they are inconsistent, the instructions from the FA master station shall prevail.

[0118] Reset count check: For transient faults, a maximum of 2 resets are allowed, and the counter is reset after each successful reset; for permanent faults, the count is terminated directly and a "Permanent Fault - Request Clearance" signal is sent to the FA master station.

[0119] Meanwhile, the control module receives "Allow automatic reset" or "Disable automatic reset" instructions from the FA master station, and generates a reset control signal only when both the local logic and the remote instructions are satisfied.

[0120] S4): The control module calculates the required discharge energy (by looking up the table based on the distance difference between the current drop position and the closing reference position) and triggers the thyristor to discharge.

[0121] Real-time position comparison: The laser displacement sensor feeds back the position at a frequency of 1kHz and compares it with the pre-stored closing reference position (accuracy ±0.1mm). When the distance is less than 2mm, the dynamic braking resistor is activated to ensure the fuse tube is smoothly positioned.

[0122] Double verification after reset: The contact resistance is measured by the four-wire Kelvin method. If it is ≤80μΩ and line continuity is detected by the injected signal (or line voltage recovery is detected), the reset is successful; otherwise, a "bad closing" alarm is issued and reported to the FA master station.

[0123] Manual intervention priority: Pressing the red "Emergency Lockout" button unconditionally disables all automatic reset operations on the control module; pressing the green "Reset Enable" button restores the automatic reset function. During on-site maintenance, first press the emergency lockout, and then press the reset enable button after maintenance is completed.

[0124] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A 10KV drop-out fuse automatic reset system, characterized in that, include: The detection module is used to detect the drop-out status of the drop-out fuse in real time. The control module, electrically connected to the detection module, is used to receive the drop status and output a reset control signal; The drive module, electrically connected to the control module, is used to receive the reset control signal and output driving force. The transmission mechanism is mechanically connected to the drive module and, under the action of the driving force, drives the fallen fuse tube to perform a reset action; Specifically, the control module is used to execute a lockout judgment logic when the drop state indicates that the fuse is in the drop position; the lockout judgment logic includes judging whether the fuse is intact based on the fuse integrity information obtained by the detection module; if the fuse is intact and meets the preset automatic reset conditions, the reset control signal is output.

2. The system of claim 1, wherein, The preset automatic reset conditions include at least one of the following: determining whether the line current is lower than a preset safety threshold, or determining whether the duration of the fuse tube being in the drop position exceeds a preset delay threshold.

3. The system of claim 1, wherein, The control module also includes a fault type identification unit; The fault type identification unit classifies the current fault as either a transient fault or a permanent fault based on the current change characteristics and drop trigger time characteristics obtained by the detection module. If the fault is classified as permanent, the control module prohibits the output of the reset control signal and outputs a fault alarm signal.

4. The system of claim 3, wherein, The control module also includes a reset count counter; The reset count counter is used to accumulate the number of automatic resets of the same fuse tube after the same fault event; when the number of automatic resets reaches the preset upper limit, the control module prohibits the output of the reset control signal and outputs an alarm signal. The fault classification result of the fault type identification unit is used to reset or maintain the counting state of the reset count counter: if it is classified as a transient fault, the reset count counter is reset; if it is classified as a permanent fault, the counting is terminated and a permanent fault alarm signal is output.

5. The system of claim 1, wherein, The control module is also used to: acquire the movement position information of the fuse tube fed back by the detection module in real time during the process of the transmission mechanism driving the fuse tube to perform the reset action, compare the movement position information of the fuse tube with the pre-stored closing reference position in real time; when the comparison result shows that the fuse tube has reached the closing position, output a stop signal to make the drive module stop outputting driving force.

6. The system of claim 5, wherein, The control module is also used to: after the fuse tube is reset to the closed position, determine whether the contact state between the fuse tube and the stationary contact reaches a preset tightness based on the contact resistance value fed back by the detection module, and determine whether the line is conductive based on the line continuity detection signal; if the contact state does not reach the preset tightness or the line is not conductive, output a fault alarm signal and prohibit subsequent automatic reset operations.

7. The system of claim 1, wherein, It also includes a communication module; The communication module is electrically connected to the control module and is used to establish bidirectional communication with the remote monitoring center to receive remote reset commands and / or upload drop status.

8. The system of claim 1, wherein, It also includes a manual operation interface; The manual operation interface is electrically connected to the control module and is used to receive on-site manual reset commands; the control module is used to prioritize responding to the on-site manual reset commands.

9. The system of claim 1, wherein, The detection module further comprises a fuse state detection unit; The fuse state detection unit is a mechanical microswitch or a photoelectric sensor, which is used for directly detecting the physical continuity of the fuse.

Images