Grounding condition self-adaptive multi-stage hybrid surge protection device

Abstract

The invention discloses a multi-stage hybrid surge protection device with a self-adaptive grounding condition, and belongs to the technical field of electric power protection. The device comprises an input terminal used for being connected with a three-phase alternating current power supply; the output terminal is used for being connected with protected electric equipment; the differential mode surge protection module is electrically connected to the input terminal, and the differential mode surge protection module is arranged between at least two phase lines of the three-phase alternating current power supply; the common-mode surge protection module is electrically connected to the input terminal, and the common-mode surge protection module comprises a gas discharge unit connected with the protection ground terminal; and the rapid fusing module is connected in series between the input terminal and the differential mode surge protection module and between the input terminal and the common mode surge protection module, and is used for realizing permanent disconnection of a downstream circuit when the current flowing through the rapid fusing module exceeds a preset fusing threshold value. According to the invention, by constructing a framework combining passive protection and intelligent active management, the protection capability, reliability and safety of the device in a severe outdoor environment are improved.

Description

Technical Field

[0001] This invention relates to the field of power protection and electrical safety technology, and in particular to a multi-stage hybrid surge protection device that can adapt to grounding conditions. Background Technology

[0002] Lightning surges and switching surges in power systems are among the main causes of damage to electrical equipment. Therefore, surge protection devices (SPDs) are widely used in various power supply systems. The core of existing surge protection technology paradigms is to construct a low-impedance discharge path from the high-potential line to the low-potential ground. This paradigm heavily relies on a stable and low-impedance grounding system to protect downstream equipment by instantaneously diverting the enormous surge energy to the ground. However, in increasingly widespread outdoor, remote, and temporary power supply scenarios, such as mountainous communication base stations, field construction sites, rural power grid terminals, and photovoltaic inverter systems, constructing and maintaining an ideal grounding system faces significant technical and economic challenges. High soil resistivity, harsh construction conditions, or cost constraints often result in grounding systems in these scenarios having high grounding resistance or even complete lack of grounding. In such "poorly grounded" or "ungrounded" electrical environments, traditional surge protection paradigms relying on grounding become completely ineffective, failing to provide effective protection for equipment and drastically increasing the risk of equipment damage and system downtime.

[0003] Therefore, existing technologies face a fundamental contradiction: the strong dependence of surge protection technology on ideal grounding, and the common reality that harsh outdoor electrical environments cannot provide ideal grounding. Summary of the Invention

[0004] One objective of this invention is to provide a protection scheme that can adapt to different grounding conditions and adopt a multi-level hybrid architecture, in order to solve the technical problem that the protection capability of existing surge protection devices is severely reduced or even completely failed in poor grounding or no grounding environments, and that they cannot effectively isolate faults to protect downstream equipment when they fail.

[0005] This application provides a multi-level hybrid surge protection device with adaptive grounding conditions. The device includes an input terminal for connecting to a three-phase AC power supply; an output terminal for connecting to the protected electrical equipment; a differential-mode surge protection module electrically connected to the input terminal, wherein the differential-mode surge protection module is disposed between at least two phases of the three-phase AC power supply and is used to absorb and clamp differential-mode surge overvoltage between the at least two phases when there is no effective protective grounding connection; a common-mode surge protection module electrically connected to the input terminal, wherein the common-mode surge protection module includes a gas discharge unit connected to a protective ground terminal and is used to discharge the common-mode surge current to the ground when the protective ground terminal is connected to an effective protective ground; and a fast-blow fuse module connected in series between the input terminal and the differential-mode surge protection module and the common-mode surge protection module, and is used to permanently disconnect the downstream circuit when the current flowing through it exceeds a preset fuse threshold.

[0006] Optionally, according to the aforementioned scheme, the differential mode surge protection module includes at least three first varistors, which are respectively connected in parallel between phase L1 and phase L2, phase L2 and phase L3, and phase L3 and phase L1 of the three-phase AC power supply.

[0007] Optionally, according to the aforementioned scheme, the common-mode surge protection module includes at least three second varistors, which are respectively connected between each phase line of the three-phase AC power supply and a common node; wherein, the gas discharge unit is connected between the common node and the protective ground terminal.

[0008] Optionally, according to the aforementioned scheme, the fast-blowout module includes three ultra-fast fuses connected in series with each phase line of the three-phase AC power supply.

[0009] Optionally, according to the aforementioned scheme, a status indication module is also included. The status indication module is linked with the differential mode surge protection module and the common mode surge protection module, and is used to provide the user with a normal or fault status indication of the device through a light-emitting diode.

[0010] Optionally, according to the foregoing scheme, the device further includes an active health monitoring and predictive isolation system for monitoring the operating status of at least one protection element in the differential-mode surge protection module or the common-mode surge protection module, and actively isolating the protection element from the circuit when the operating status of the protection element meets preset failure precursor conditions. The active health monitoring and predictive isolation system includes a control unit; at least one sensing unit associated with the at least one protection element for monitoring one or more operating parameters of the protection element; and at least one switching unit connected in series with the at least one protection element and controlled by the control unit.

[0011] Optionally, according to the aforementioned scheme, the device further includes a dynamic clamping level adjustment system for actively adjusting the effective clamping voltage of the differential mode surge protection module based on external environmental threat data. The dynamic clamping level adjustment system includes a control unit, an external sensor interface, and a bias injection array. The bias injection array injects a controllable DC bias voltage into the differential mode surge protection module through a high-impedance coupling circuit.

[0012] The beneficial effects of this application are as follows:

[0013] Through a grounding condition adaptive architecture, the differential mode protection core works effectively when there is no grounding, and the common mode discharge path is activated to form collaborative protection when there is grounding, thus achieving universality for different outdoor electrical environments. Through a multi-level hybrid protection system composed of fuses, varistors, and gas discharge tubes, the surge energy is weakened step by step and managed in a refined manner. By placing the fast-blow unit at the top of the protection circuit, a fail-safe mechanism is constructed, which solves the fundamental safety hazard that may be caused by the failure of traditional protectors.

[0014] Furthermore, by introducing an active health monitoring and predictive isolation system, the device is upgraded from passive protection to intelligent active management. It can predictively isolate the protective components before they suffer catastrophic short-circuit failure, thereby eliminating the fire risk caused by short circuits due to deterioration of the protective components. It also enables component-level fault diagnosis, improving the safety redundancy and maintainability of the entire system.

[0015] Furthermore, by integrating a dynamic clamping level adjustment system, this invention resolves the inherent contradiction between the temporary overvoltage (TOV) withstand capability and the low residual voltage fine protection of traditional surge protectors. It can maintain a high clamping voltage to ensure its own safety when the power grid is stable, and proactively and instantaneously reduce the clamping voltage to the optimal protection level when a lightning threat occurs, thus providing adaptive protection for sensitive downstream equipment without sacrificing safety. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a lightning protection and surge protection circuit is provided for an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram illustrating the connection between the lightning and surge protection device provided in this embodiment of the invention and the electrical equipment.

[0019] Figure 3 This is a schematic diagram of a proactive health monitoring and predictive isolation system provided in a preferred embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the operation of a dynamic clamping level adjustment system provided in another preferred embodiment of the present invention.

[0021] Figure 5 This is a circuit integration schematic diagram of a dynamic clamping level adjustment system provided in another preferred embodiment of the present invention. Detailed Implementation

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

[0023] 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 one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0024] This embodiment provides a multi-level hybrid surge protection device with adaptive grounding conditions. In a specific implementation, the core of this device lies in constructing a multi-level hybrid protection architecture that can adapt to different grounding conditions. Specifically, the first level is upstream fast-blowout isolation, the second level is the core differential-mode surge absorption, and the third level is condition-triggered common-mode surge discharge. These three levels work together to achieve adaptive surge protection in various complex outdoor electrical environments, including no grounding, poor grounding, and good grounding. This device solves the technical problems of existing surge protection devices over-relying on good grounding, leading to protection failure in harsh environments, and the inability to isolate faults after the failure of the protection components themselves, thus causing secondary safety risks. It achieves the beneficial effect of ensuring the safety of downstream equipment while improving the overall operational reliability of the protection system.

[0025] Reference Figure 1 and Figure 2The grounding condition adaptive multi-level hybrid surge protection device provided in this embodiment of the invention is installed between the power supply and the electrical equipment, for example, in a distribution box. Its input terminal CN1 is connected to a three-phase AC power supply, and its output terminal CN2 is connected to the downstream electrical equipment that needs protection. According to the appendix... Figure 1 Both input terminal CN1 and output terminal CN2 are four-pin connectors (KV1270-4P). Pins 1, 2, and 3 correspond to phase lines L1, L2, and L3 of the three-phase power supply, respectively, and pin 4 is connected to protective earth (PE). The core protection circuit of the device mainly consists of three functional modules: a fast-blow fuse module (F1, F2, F3), a differential mode surge protection module (RV1-RV6), and a common mode surge protection module (RV7, RV8, RV9, GDT1). The PE terminal is the protective earth connection terminal.

[0026] The working principle or implementation method of the grounding condition adaptive multi-level hybrid surge protection device provided by the present invention will be described in detail below. This device achieves its protection function by performing the following steps:

[0027] S100: A differential mode surge protection network is installed between at least two phases of a three-phase AC power supply. The differential mode surge protection network is configured to absorb and clamp differential mode surge overvoltages between the at least two phases in the absence of an effective protective grounding connection.

[0028] This step establishes the core function of the entire protection system: to absorb and suppress differential-mode surge energy on-site without relying on the ground as a discharge channel. This is crucial to ensuring the device retains basic protection capabilities even in environments with poor or no grounding. Differential-mode surges are typically caused by lightning strikes, the start-up and shutdown of large inductive loads in the power grid, and other factors, manifesting as an abnormal increase in voltage between live wires. The differential-mode surge protection network uses highly nonlinear, low-response-time voltage clamping elements connected in parallel between these lines. When the inter-line voltage exceeds the normal operating voltage range, the resistance of these elements instantly drops from megaohms to milliohms, forming a transient low-resistance path. This directly diverts the surge current from the higher-voltage wire to the lower-voltage wire, clamping the inter-line voltage to a safe level that the equipment can withstand. Since the entire energy absorption loop is a closed loop formed between phase wires, its operating principle does not depend on the existence of a ground discharge path, thus achieving "decoupling" from grounding conditions.

[0029] In one specific embodiment, the differential mode surge protection network consists of six high-energy metal oxide varistors (MOVs) RV1 to RV6, forming a protection topology composed of parallel element groups. Specifically, the first protection group consists of varistor RV5 and varistor RV1 connected in parallel, bridging phases L1 and L2 of the three-phase power supply. The second protection group consists of varistor RV3 and varistor RV4 connected in parallel, bridging phases L1 and L3 of the three-phase power supply. The third protection group consists of varistor RV6 and varistor RV2 connected in parallel, bridging phases L2 and L3 of the three-phase power supply. This topology, by connecting two varistors in parallel, aims to divert the total surge current flowing through the branch, thereby multiplying the current-carrying capacity and energy tolerance level of the branch. The selection of these varistors requires precise calculation. Their nominal voltage... It must be higher than the maximum fluctuation value of the normal operating voltage of the power grid. For a 380V system, the varistor for phase-to-phase protection (such as RV1, RV5, etc.) is usually selected as a component with a varistor voltage of 820V to 1000V.

[0030] For example, suppose a surge pulse induced by a remote lightning strike is superimposed on phases L1 and L2, causing the voltage difference between L1 and L2 to spike from a normal RMS value of 380V (peak value approximately 537V) to 6000V within 10 microseconds. At this point, the first protection group connected between L1 and L2 will activate. When the voltage between L1 and L2 exceeds the varistor voltages of RV1 and RV5 (e.g., 820V), the internal grain boundary barriers of the two MOVs are broken down, and their resistance drops instantaneously from an insulating state greater than 1GΩ to a conducting state of approximately 0.1Ω. Since RV1 and RV5 are connected in parallel, the voltage across them is forced to be clamped to almost the same value, assuming their residual voltage (clamping voltage) under this current... Both are 1500V. A huge total surge current will flow through this parallel protection group. Assuming the total surge current is 44kA, due to the parallel current sharing effect, this current will theoretically be equally distributed to RV1 and RV5, meaning each component will bear approximately 22kA of current. This process forcibly clamps the voltage between L1 and L2 to around 1500V, while distributing the huge surge energy that would originally need to be borne by a single component to both components, greatly improving the reliability of the protection. The entire process is completed within tens of nanoseconds and does not involve the PE ground wire at all.

[0031] S200: A branch line is laid between each phase line of the three-phase AC power supply and a common node, and a gas discharge unit is laid between the common node and a protective ground terminal to form a common mode surge discharge network. The common mode surge discharge network is configured to discharge the common mode surge current to the ground when the protective ground terminal is connected to an effective protective ground.

[0032] This step establishes a common-mode protection function that complements the differential-mode protection network. Common-mode surges manifest as a simultaneous and equal increase in the potential of all phase conductors to ground, commonly caused by direct lightning strikes or near-field lightning strikes passing through the grounding system, resulting in ground potential backflash. In well-grounded environments, if such surges are not suppressed, the extremely high voltage to ground can still break down the insulation of equipment, causing damage. The core idea of ​​this common-mode surge discharge network is to provide a controlled path to ground that only conducts when a common-mode surge occurs. During normal operation, this path must present a high-resistance state to ensure complete isolation between the phase conductors and ground, preventing leakage.

[0033] In a strict basis Figure 1 In a specific embodiment, the network consists of varistors RV7, RV8, RV9 and a gas discharge tube (GDT) GDT1, forming a "Y" connection. One end of RV7, RV8, and RV9 is connected to the three phases L1, L2, and L3 respectively, while the other ends converge at a common node (star point). The gas discharge tube GDT1 is connected between this common node and the protective earth (PE) terminal. This structure is called an MOV+GDT series topology, which combines the advantages of fast MOV response and large current capacity and extremely low leakage current of GDT. During normal operation, GDT1 contains inert gas, exhibiting extremely high insulation resistance (>10GΩ), ensuring electrical isolation between the star point and ground, thereby avoiding continuous ground leakage caused by the leakage current of the MOV itself (even if very small), which is crucial for some systems with residual current devices (RCDs). When a common-mode surge occurs, the potential of the three phases L1, L2, and L3 to ground rises simultaneously, and this high voltage is applied to the "phase line-MOV-GDT-ground" path. When the voltage rises to a level sufficient to break down the gas arc inside the GDT (the DC breakdown voltage of the GDT, e.g., 600V), GDT1 instantaneously conducts, forming an extremely low impedance path from the common node to ground. At this moment, a huge common-mode surge current flows from the three phases through RV7, RV8, and RV9 respectively, converges to the common node, and is then safely discharged to ground through the conducting GDT1. The role of RV7, RV8, and RV9 here is to perform primary voltage limiting and current sharing, and to work in conjunction with GDT1.

[0034] For example, suppose a lightning strike nearby causes a ground potential backflash, instantly raising the three-phase ground potential of the entire power supply system (L1, L2, L3) by 10000V. At this time, the PE terminal of the device is connected to the ground via a grounding wire with an ideal grounding resistance of 4Ω. This 10000V common-mode voltage acts on the three parallel branches RV7+GDT1, RV8+GDT1, and RV9+GDT1. Assume the selected GDT1 has a DC breakdown voltage of 600V and a pulse breakdown voltage (at a voltage rise rate of 1kV / μs) of 1200V. When the voltage at the common node exceeds 1200V, the electrode gap inside GDT1 is arc-broken, and its conduction voltage rapidly drops to an extremely low arc voltage, such as 20V. At this point, a path from the common node to ground is established. The magnitude of the surge current is mainly limited by the line impedance and MOV. Assuming that the residual voltage of RV7, RV8, and RV9 is 1000V under surge current, then the current through each branch is approximately... More intuitively, the total discharge current It will flow into the ground through GDT1, and generate a voltage drop across the grounding resistance. If the peak discharge current is 50kA, a discharge current will be generated at the PE terminal. The instantaneous high voltage. Nevertheless, due to the clamping effect of RV7, RV8, and RV9, the voltage of lines L1, L2, and L3 relative to the PE terminal is limited to... This voltage is far below the insulation withstand level of the equipment to ground. Therefore, even if the ground potential is significantly raised, the line-to-ground voltage at the equipment port is effectively controlled within a safe range.

[0035] If the device's PE terminal is not connected or poorly grounded (e.g., grounding resistance as high as 100Ω), the common-mode discharge network will not function effectively because the discharge current cannot flow into the ground. In this case, the potential of the entire system will "float" and rise, but due to the presence of the differential-mode protection network constructed in S100, the voltage difference between the lines is still clamped, and the equipment can still be protected from damage by differential-mode surges, demonstrating the robustness of the present invention.

[0036] S300: A fast-blow fuse unit is connected in series at the input terminals of each phase line of the three-phase AC power supply and upstream of the differential mode surge protection network and the common mode surge discharge network. The fast-blow fuse unit is configured to permanently disconnect the downstream circuit when the current flowing through it exceeds a preset fusing threshold.

[0037] This step adds a crucial "safety valve" mechanism to the entire protection system: fail-safe protection. Surge protection components (especially MOVs) gradually degrade in performance after being subjected to multiple surge impacts or surges exceeding their energy capacity. A typical mode of degradation is increased leakage current, which can eventually lead to thermal runaway, causing a permanent transition from a high-resistance state to a low-resistance state (short circuit). Without upstream overcurrent protection, a short-circuited MOV will create a continuous phase-to-phase or phase-to-ground short circuit under normal 380V power frequency voltage. This will generate a huge short-circuit current, potentially causing the protection device itself to catch fire or explode, and severely damaging the entire power distribution system. This step prevents such secondary disasters by connecting a precisely selected fast-blow fuse in series before all surge protection components.

[0038] In one specific embodiment, the fast-blow unit consists of three fuses, F1, F2, and F3, connected in series on phase lines L1, L2, and L3, respectively. The selection of these fuses is one of the key technical aspects of this design. First, their rated current must be greater than the normal operating current and starting current of the downstream electrical equipment to ensure that they do not blow during normal operation. For example, if the downstream equipment is a motor with a rated current of 10A, considering that its starting current may reach 5-7 times that, i.e., 50-70A, but the duration is very short, the rated current of the fuse should be selected as 16A or 20A, and it should have a certain time delay characteristic to withstand the starting impact. Second, the fusing characteristic (It curve) of the fuse must match the thermal failure characteristics of all downstream MOVs. Specifically, when an MOV begins to deteriorate and the leakage current gradually increases, the power frequency current flowing through it must be able to reliably disconnect the upstream fuses before the MOV catches fire or is damaged due to overheating. This requires the fuse to have an ampere-second characteristic (It curve). The value is less than the maximum energy that the MOV can withstand. Usually, gG / gL class or faster FF (ultra-fast) class fuses are selected, as they are very sensitive to overcurrent and can interrupt fault current in milliseconds.

[0039] For example, suppose the varistor RV5 used for differential mode protection between L1 and L2 suffers severe performance degradation after being subjected to multiple lightning strikes, and its internal structure is broken down and short-circuited. At this time, a direct short circuit is formed from phase L1 to phase L2, and the short-circuit current... Assuming a very low line impedance, the short-circuit current can reach hundreds of amperes, for example, 380A. This enormous current will flow through upstream fuses F1 and F2. Assuming F1 and F2 are FF-class fuses with a rated current of 16A, their fusing time at 380A can be found on their It characteristic curves, typically less than 1 millisecond. At the instant the fuse blows, the power supply to phases L1 and L2 is permanently cut off, thus preventing the enormous energy from continuously flowing into the failed MOV, avoiding the risk of it burning or exploding due to overheating, and also protecting the entire circuit and downstream equipment.

[0040] S400: An integrated active health monitoring and predictive isolation system based on pixel-driven circuitry.

[0041] To further enhance the reliability and maintainability of this invention, in a preferred embodiment, the device integrates an active health monitoring and predictive isolation system on top of the passive protection constructed in S100 to S300. This system treats each or each group of critical surge protection components (such as varistor MOVs) as an independently addressable and controllable "protection pixel," thereby transforming the entire protection network from a passive whole into an actively manageable intelligent protection matrix. The system aims to proactively disconnect varistors from the circuit before they suffer catastrophic short-circuit failure due to long-term degradation by monitoring for early signs of failure (such as abnormally increased leakage current), thus eliminating secondary safety risks caused by protection component failure and providing maintenance personnel with precise fault location.

[0042] See attached document Figure 3 This diagram illustrates the principle block diagram of an active health monitoring and predictive isolation system. In a specific embodiment, the system comprises three core components: a control unit (MCU), multiple sensing units, and multiple switching units. The protection elements 1 to N (e.g., RV7, RVx, etc.) in the protection element matrix correspond one-to-one with the sensing units 1 to N in the sensing unit array through physical association. Simultaneously, each protection element also corresponds one-to-one with its corresponding switching units 1 to N connected in series in the circuit. The control unit, as the core of the system, acquires monitoring signals from the sensing unit array via a data bus, processes them through internal algorithms, sends isolation control signals to the switching unit array via a control bus, and outputs information to external status indication and alarm interfaces.

[0043] The control unit is typically a microcontroller (MCU) responsible for executing preset monitoring algorithms, processing sensor data, making isolation decisions, and controlling the actions of the switching unit.

[0044] The sensing unit functions to monitor the operating status of each "protected pixel" (i.e., one or a group of MOVs) in real time. In one embodiment, the sensing unit can be a low-resistance precision sampling resistor connected in series with the MOV. For example, a precision sampling resistor with a resistance of 0.01 ohms is connected in series with the ground terminal of the varistor RV7 in the common-mode protection branch. Under normal power frequency voltage, a healthy RV7 has extremely low leakage current, in the microamp level, so the voltage drop across the sampling resistor is close to zero. When RV7 begins to degrade, its leakage current abnormally increases to the milliamp level or even higher. The control unit periodically measures the voltage drop across the sampling resistor using a high-precision analog-to-digital converter (ADC) and calculates the real-time leakage current value according to Ohm's law (I = V / R). In another embodiment, the sensing unit can be a negative temperature coefficient (NTC) thermistor, which is physically attached to the surface of the RV7 housing. An abnormally increased leakage current will inevitably cause the MOV to heat up. The control unit can calculate the real-time surface temperature of the MOV by monitoring the change in the resistance of the thermistor.

[0045] The switching unit functions to execute isolation commands issued by the control unit. Each "protected pixel" is equipped with an independent switching unit connected in series. This switching unit can be a high-power metal-oxide-semiconductor field-effect transistor (MOSFET) or a solid-state relay (SSR). These solid-state switches have advantages such as fast response speed, no mechanical contacts, and long lifespan.

[0046] The workflow of this system is as follows:

[0047] After the device is powered on, the control unit places all switching units in the closed (conducting) state to ensure that all protection components are in normal online working mode. Subsequently, the control unit enters a cyclic monitoring program, which sequentially "scans" each sensing unit at a preset frequency (e.g., every 100 milliseconds) to acquire real-time leakage current or temperature data of all monitored MOVs.

[0048] The control unit internally stores a preset degradation threshold. For example, for leakage current monitoring, this threshold can be set to 5 mA; for temperature monitoring, it can be set to 40°C above ambient temperature. These thresholds are far below the current or temperature at which the MOV experiences thermal runaway and causes upstream fuses F1-F3 to trip, but significantly higher than the normal operating parameters of a healthy MOV. The control unit compares the parameter values ​​monitored in real time with this degradation threshold.

[0049] If, during a scan, the control unit detects that the leakage current of the varistor RV7 has reached 5.1mA, exceeding the 5mA threshold, it determines that RV7 has entered an irreversible degradation stage and is at risk of short-circuit failure. At this point, the control unit immediately executes a predictive isolation procedure: it sends a control signal (e.g., a low-level signal for an N-channel MOSFET) to the gate of the MOSFET switching unit connected in series with RV7, causing the MOSFET to rapidly turn off within microseconds.

[0050] After completing the isolation action, the MOSFET permanently disconnects the failed RV7 from the circuit, preventing further increase in leakage current and eventual short circuit. Simultaneously, the control unit can send a precise alarm message to the host computer via a communication interface (such as RS485), such as "Common mode branch L1 phase protection element RV7 deteriorated and isolated," or illuminate a specific LED indicator, greatly facilitating on-site maintenance. At this time, other protection elements of the device (such as RV8, RV9, etc.) continue to operate normally, ensuring a certain degree of degraded operation capability for the system, rather than complete device failure.

[0051] Through the above mechanism, this invention upgrades the traditional protection method, which can only passively melt after the component is completely short-circuited, into an intelligent protection method that can actively intervene before failure.

[0052] S500: Integrates a dynamic clamping level adjustment system based on pixel driving circuitry.

[0053] To address the inherent conflict between safety margin and protection accuracy in traditional surge protectors, this invention, in a more preferred embodiment, further integrates a dynamic clamping level adjustment system. This system comprises:

[0054] The health monitoring system in the S400 treats protected components as pixels whose status can be read, while this system treats protected components as pixels whose operating parameters can be written to or driven. Its core function is to proactively adjust the effective clamping voltage of the differential mode surge protection module based on the real-time external environmental threat level, thereby achieving dynamic optimization of protection performance.

[0055] See attached document Figure 4This diagram illustrates the protection effect of the system under different operating modes. The horizontal axis represents time, and the vertical axis represents voltage. The dotted line in the diagram represents a high-voltage input surge pulse without protection. When the system is in high-safety standby mode (e.g., on a clear day without lightning threat), its clamping voltage is maintained at a relatively high default value (e.g., 1500V), as shown by the dotted line. When an external sensor (e.g., an atmospheric electric field meter) detects a lightning threat and triggers an early warning, the system enters a fine protection mode. At this time, the clamping voltage is actively reduced to a lower level (e.g., 1400V), as shown by the solid line. It can be seen that in fine protection mode, the residual voltage after passing through this device is lower, providing more precise protection for downstream equipment.

[0056] Reference Figure 5 The figure shows a schematic diagram of the integrated circuitry of the dynamic clamping level adjustment system. In one specific embodiment, the dynamic clamping level adjustment system does not change... Figure 1 The core circuit structure shown is not integrated into a single system, but rather operates in parallel as a coordinated control system. It includes: a control unit (MCU), an external sensor (such as an atmospheric electric field meter) and its interface, a bias injection array, and a high-impedance coupling circuit.

[0057] Traditional surge protectors have a fixed clamping voltage, requiring a compromise between two conflicting objectives: on the one hand, the clamping voltage needs to be high enough to ensure the protector itself does not malfunction during temporary overvoltage (TOV) events in the power grid; on the other hand, the clamping voltage needs to be low enough to provide effective overvoltage protection for increasingly sophisticated downstream electronic equipment. This system completely resolves this contradiction by introducing an active regulation mechanism.

[0058] In one specific embodiment, the dynamic clamping level adjustment system remains unchanged. Figure 1 Instead of the core circuit structure shown, it works in parallel as a cooperative control system, including: a control unit (which can be reused with the control unit in S400), an external sensor interface, a bias injection array, and a high-impedance coupling circuit.

[0059] The external sensor interface is used to receive threat level data from external environmental monitoring equipment. For example, this interface can be connected to an atmospheric electric field meter. The atmospheric electric field meter can monitor the intensity and polarity changes of the atmospheric electric field near the device, which is a direct precursor to lightning activity. When the atmospheric electric field intensity exceeds a warning threshold, for example, abnormally increasing from the normal 0.1 kV / m to 5 kV / m, it indicates that a thunderstorm cloud is approaching, and the risk of lightning strikes increases sharply.

[0060] The bias injection array is a group of low-current DC voltage sources that are precisely controlled by the control unit and isolated from each other. Each voltage source in the array corresponds to a protection branch in the differential mode protection network (e.g., corresponding to the RV1 / RV5 parallel group).

[0061] The high-impedance coupling circuit allows the control system to inject a weak DC control signal into the high-voltage AC line without affecting the normal operation of the main circuit. For example, for the RV1 / RV5 protection group connected across L1-L2, the coupling circuit can consist of two 10MΩ high-voltage precision resistors connected in series with a bias injection voltage source, and then connected in parallel across the RV1 / RV5 protection group.

[0062] The workflow of this system is as follows:

[0063] Under normal weather conditions, no threat is detected by the external sensor interface, and the atmospheric electric field strength is at a safe level. At this time, the control unit commands the entire bias injection array to shut down, preventing the injection of bias voltage into any protection branch. The clamping voltage of the differential mode protection network, with its inherently high physical design value (e.g., 1500V), ensures the highest possible TOV withstand capability.

[0064] When the atmospheric electric field meter detects that the field strength exceeds the warning threshold of 5kV / m, it sends the threat signal to the control unit through the external sensor interface.

[0065] Upon receiving a threat signal, the control unit immediately enters protection mode, addresses all differential mode protection branches, and drives the corresponding voltage sources in the bias injection array to start operating. For example, the control unit commands the voltage sources corresponding to branches L1-L2 to apply a 100V DC bias voltage to the RV1 / RV5 parallel group via a high-impedance coupling circuit. Due to the nonlinear voltage-current characteristic of the varistor, this weak DC bias voltage effectively pre-offsets its conduction threshold point. For a surge pulse with the same polarity as the bias voltage, the voltage barrier it needs to overcome is reduced. This causes the effective clamping voltage of this protection branch to dynamically and instantaneously decrease from the original 1500V to 1400V.

[0066] After the surge event ends, or when the atmospheric electric field meter reading falls below the safety threshold after a period of time (e.g., 10 minutes), the control unit automatically switches the system back to high-safety standby mode, removes all bias voltages, and restores the clamping voltage to its original higher level.

[0067] Through this driving method, the device of the present invention can act as a protector with a high safety margin when the power grid is stable; and at the moment when the threat of lightning approaches, it can intelligently transform into a protector with extremely low residual voltage, thereby ensuring its own absolute safety while providing dynamic and optimal protection for the back-end equipment.

[0068] This invention also provides a grounding condition adaptive multi-level hybrid surge protection device, which is the physical implementation of the above-described method. (Refer to...) Figure 1 and Figure 2 The device may specifically include:

[0069] Input terminal module CN1: Typically uses high-specification terminal blocks or industrial connectors, capable of carrying rated current and providing excellent electrical connection reliability. Its terminals include L1, L2, L3 three-phase interfaces and a PE interface. The terminal material is usually tin-plated copper, and the housing is made of flame-retardant engineering plastic, ensuring a safe and secure connection.

[0070] Output terminal module CN2: Similar to the input terminal module, it is used to connect the protected load device. The input and output terminals are physically separated to prevent incorrect connection.

[0071] Fast-blow module: Consists of fuses F1, F2, and F3 and their bases. In some advanced designs, fuse bases with status indicators can be used. When a fuse blows, an LED indicator on the base will light up, or a mechanical indicator will pop up, allowing maintenance personnel to quickly locate the faulty phase. The fuses are installed at the farthest input of the PCB board, ensuring that all subsequent circuits are protected.

[0072] Differential mode surge protection module: strictly in accordance with the appendix Figure 1 It mainly consists of varistors RV1, RV2, RV3, RV4, RV5, and RV6. These varistors are typically large-diameter circular chip components (e.g., 20mm, 32mm in diameter), directly soldered onto a PCB board designed for high current. The PCB traces are specially designed to be as short, straight, and wide as possible to reduce parasitic inductance in surge paths. Parasitic inductance In rapidly changing surge current This generates an additional voltage drop. This voltage will be superimposed on the residual voltage of the MOV, reducing protection performance. Therefore, optimizing the PCB layout is a key step in improving protection effectiveness.

[0073] Common-mode surge protection module: Composed of varistors RV7, RV8, RV9 and gas discharge tube GDT1. The GDT is typically a ceramic-encapsulated two- or three-electrode element. It is connected in series between the MOV common star point and the PE terminal. Because the GDT can discharge extremely large lightning currents, its connection to the PE terminal must be extremely short and sufficiently robust.

[0074] Status Indicator Module (Optional): This module provides visual information about the device's operating status. A simple implementation involves connecting a thermal trip mechanism in series in each phase's surge protection branch. This mechanism is linked to a microswitch. Under normal operation, the switch is normally closed, illuminating a green "normal" LED. When the MOV in this branch deteriorates due to overcurrent or overheating, the thermal trip mechanism activates, disconnecting the branch and simultaneously driving the microswitch to switch states, extinguishing the green LED and illuminating a red "fault" LED. This design provides users with clear maintenance and replacement prompts.

[0075] Housing and Encapsulation Module: The entire PCB circuit board is encapsulated within a robust, high-protection housing. Considering outdoor applications, the housing material is typically an engineering plastic with UV resistance (such as polycarbonate PC) or die-cast aluminum. Silicone seals are used at the housing seams, and waterproof connectors (Granbond connectors) are used at cable entry and exit points to ensure an overall protection rating of IP65 or higher. An IP65 rating means complete protection against dust ingress and the ability to withstand low-pressure water jets from any direction, sufficient to handle outdoor weather conditions. The housing design also considers heat dissipation; for high-power applications, heat sinks may be incorporated into the aluminum housing.

[0076] In summary, this invention, through its innovative grounding condition adaptive architecture and multi-level hybrid protection topology, combined with a pre-emerged fail-safe design and optional pixel-driven active health monitoring and predictive isolation system and dynamic clamping level adjustment system, provides a reliable, safe, multi-layered, and intelligently manageable surge protection device for 380V electrical equipment under various grounding conditions. By decoupling the protection function into a groundless core differential-mode absorption and optional common-mode grounding discharge, and combining it with a front-end fast-blowout isolation mechanism, it fundamentally solves the limitations and safety hazards of traditional surge protection technologies in practical applications, possessing extremely high engineering application value and promising prospects for widespread adoption.

[0077] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit described above can be implemented in hardware.

[0078] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A multi-stage hybrid surge protection device with adaptive grounding conditions, characterized by, The device comprises: an input terminal for connecting a three-phase AC power supply; an output terminal for connecting a protected electrical device; a differential mode surge protection module electrically connected to the input terminal, the differential mode surge protection module being arranged between at least two phase lines of the three-phase AC power supply, for absorbing and clamping a differential mode surge overvoltage between the at least two phase lines under the condition of no effective protection grounding connection; a common mode surge protection module electrically connected to the input terminal, the common mode surge protection module comprising a gas discharge unit connected to a protection ground terminal, the common mode surge protection module being configured to discharge a common mode surge current to the ground when the protection ground terminal is connected to an effective protection ground; a fast-fuse module connected in series between the input terminal and the differential mode surge protection module and the common mode surge protection module, for permanently disconnecting a downstream circuit when a current flowing therethrough exceeds a preset fuse threshold.

2. The apparatus of claim 1, wherein, The differential mode surge protection module comprises at least three first varistors connected in parallel between L1 phase and L2 phase, L2 phase and L3 phase, and L3 phase and L1 phase of the three-phase AC power supply, respectively.

3. The apparatus of claim 1 or 2, wherein, The common mode surge protection module comprises: at least three second varistors connected between each phase line of the three-phase AC power supply and a common node, respectively; wherein the gas discharge unit is connected between the common node and the protection ground terminal.

4. The apparatus of claim 1, wherein, The fast-fuse module comprises three ultra-fast fuses connected in series on each phase line of the three-phase AC power supply, respectively.

5. The apparatus of claim 1, wherein, Further comprising: a status indication module associated with the differential mode surge protection module and the common mode surge protection module, for providing a normal or fault status indication of the device to a user through a light-emitting diode.

6. The apparatus of claim 1, wherein, Further comprising: an active health monitoring and predictive isolation system for monitoring a working state of at least one protection element in the differential mode surge protection module or the common mode surge protection module, and actively isolating the protection element from a circuit when the working state of the protection element meets a preset failure precursor condition.

7. The apparatus of claim 6, wherein, The active health monitoring and predictive isolation system comprises: a control unit; at least one sensing unit associated with the at least one protection element, for monitoring one or more working parameters of the protection element and outputting a monitoring signal to the control unit; at least one switching unit connected in series with the at least one protection element and controlled by the control unit.

8. The apparatus of claim 7, wherein, The working parameters include a leakage current or a temperature of the protection element.

9. The apparatus of claim 1, wherein, Further comprising: a dynamic clamping level adjustment system for actively adjusting an effective clamping voltage of the differential mode surge protection module based on external environmental threat data.

10. The apparatus of claim 9, wherein, The dynamic clamping level adjustment system comprises: a control unit; an external sensor interface for receiving the external environmental threat data; a bias injection array controlled by the control unit, the bias injection array injecting a controllable DC bias voltage to at least one protection branch in the differential mode surge protection module through a high-impedance coupling circuit to change an effective clamping voltage of the protection branch.

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