1U plug-in maintenance-free power supply surge protection method and protector

Abstract

The invention relates to the technical field of power supply surge protection, and discloses a 1U plug-in maintenance-free power supply surge protection method and protector, and the method comprises the steps: monitoring the terminal voltage of a piezoresistor in real time through a voltage comparator, and triggering clamping discharge within nanosecond response time; a low-resistance discharge channel is formed by utilizing the avalanche breakdown characteristic of the crystal boundary layer of the piezoresistor, surge current is rapidly discharged to a protection ground wire, meanwhile, residual voltage is clamped below a preset limit value, and rear-end load equipment is effectively protected against overvoltage damage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power surge protection, and in particular to a 1U plug-in maintenance-free power surge protection method and protector. BACKGROUND

[0002] The traditional guide rail type surge protector uses zinc oxide varistors as core discharge elements, which can achieve surge current clamping and discharge, but faces significant technical bottlenecks in long-term operation. The grain boundary layer of the varistor gradually deteriorates after withstanding multiple surge impacts, causing the leakage current to increase from the normal microampere level to the milliampere level. The continuous leakage power consumption causes the core temperature to abnormally rise. Without timely protection mechanism, it will cause thermal runaway and even fire accidents, seriously threatening the safety of power distribution systems and load devices. The existing surge protector lacks automatic protection function after deterioration, and the maintenance personnel need to regularly manually detect the leakage current and insulation performance of the varistor, which is a large amount of maintenance work and difficult to find deterioration hazards in time. The traditional product occupies 2U or more cabinet height, which is difficult to install in a space-limited cabinet environment. In addition, the screw terminal connection method is used, and the replacement of the fault module requires power-off, screw disassembly, and re-wiring complex operations, which takes more than 15 minutes of maintenance time, causing the power distribution system to be out of power and affecting the normal operation of the load device. SUMMARY

[0003] The present application provides a 1U plug-in maintenance-free power surge protection method and protector. The present application monitors the end voltage of the zinc oxide varistor in the L-PE branch in real time through the voltage comparator and triggers the clamping discharge within nanosecond response time. The low-resistance discharge channel is formed by using the avalanche breakdown characteristics of the grain boundary layer of the varistor, the surge current is quickly discharged to the protective ground, and the residual voltage is clamped below the preset limit, effectively protecting the rear-end load device from overvoltage damage.

[0004] The first aspect of the present application provides a 1U plug-in maintenance-free power surge protection method, which comprises: monitoring the end voltage of the zinc oxide varistor in the L-PE branch, and outputting a clamping discharge start signal when the end voltage exceeds a preset start voltage threshold; the zinc oxide varistor receives the clamping discharge start signal, and jumps from a high resistance state to a low resistance state within a preset response time, discharges the surge current to the PE ground, and clamps the residual voltage below the preset residual voltage limit.

[0005] In combination with the first aspect, in the first implementation manner of the first aspect of the present application, monitoring the end voltage of the zinc oxide varistor in the L-PE branch, and outputting a clamping discharge start signal when the end voltage exceeds a preset start voltage threshold, comprises: Collect the terminal voltage of the zinc oxide varistor in the L-PE branch and transmit the terminal voltage to the positive input terminal of the voltage comparator; The voltage comparator compares the terminal voltage with a preset starting voltage threshold at the negative input terminal, and outputs a high-level trigger pulse when the terminal voltage is greater than the preset starting voltage threshold. The high-level trigger pulse is subjected to RC filtering processing, and a clamping and discharge starting signal is output.

[0006] In combination with the first aspect, in a second implementation manner of the first aspect of the application, the RC filtering processing of the high-level trigger pulse outputs a clamping and discharge starting signal, including: The high-level trigger pulse is input into an RC filter circuit, and interference spikes with a duration less than a preset pulse width threshold in the high-level trigger pulse are filtered out to obtain a filtered pulse signal, and when the duration is greater than the preset pulse width threshold, a clamping and discharge starting signal is output and a trigger time is latched.

[0007] In combination with the first aspect, in a third implementation manner of the first aspect of the application, the zinc oxide varistor receives the clamping and discharge starting signal, and within a preset response time, the zinc oxide varistor jumps from a high resistance state to a low resistance state, discharges a surge current to a PE ground and clamps a residual voltage to below a preset residual voltage limit, including: The zinc oxide varistor receives the clamping and discharge starting signal. The grain boundary layer inside the zinc oxide varistor undergoes avalanche breakdown under the action of the clamping and discharge starting signal, and the resistance value of the zinc oxide varistor jumps from a high resistance state to a low resistance state within a preset response time, forming a discharge channel from the L line to the PE ground to make the surge current flow to the PE ground through the zinc oxide varistor. The zinc oxide varistor generates a clamping voltage during the process of bearing the surge current, and the clamping voltage is less than the preset residual voltage limit, and after the decay of the surge current, the resistance value of the zinc oxide varistor rises to a high resistance state within a preset recovery time.

[0008] In combination with the first aspect, in a fourth implementation manner of the first aspect of the application, the zinc oxide varistor generates a clamping voltage during the process of bearing the surge current, and the clamping voltage is less than the preset residual voltage limit, and after the decay of the surge current, the resistance value of the zinc oxide varistor rises to a high resistance state within a preset recovery time, including: The zinc oxide varistor bears the surge current in a low resistance state, and a clamping voltage is generated across the zinc oxide varistor and absorbs surge energy to convert it into heat deposited in the ceramic matrix, causing the core temperature to instantaneously rise. When the surge current decays to below a preset current threshold, the terminal voltage drops, and the grain boundary barrier of the zinc oxide varistor recovers, causing the resistance to rise back to a high resistance state within a preset recovery time.

[0009] In conjunction with the first aspect, the fifth implementation of the first aspect of the present invention further includes: The core temperature is collected by an NTC thermistor attached to the back of the ceramic substrate in the zinc oxide varistor, and the voltage signal of the NTC thermistor is converted into the core temperature. When the core temperature continues for a preset duration exceeding a preset warning temperature threshold and the temperature rise rate exceeds a preset temperature rise rate threshold, a degradation flag is output.

[0010] In conjunction with the first aspect, the sixth implementation of the first aspect of the present invention further includes: The thermal fuse connected in series in the zinc oxide varistor branch is thermally coupled to the ceramic substrate of the zinc oxide varistor through a thermally conductive material. When the core temperature reaches a preset tripping temperature threshold, heat is transferred to the thermal fuse through the thermally conductive material, causing the internal fusible alloy temperature to rise. When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid within the preset melting time, causing the current path to be interrupted, and the thermal fuse completely disconnects and cuts off the branch current of the zinc oxide varistor.

[0011] In conjunction with the first aspect, in the seventh implementation of the first aspect of the present invention, when the temperature of the fusible alloy reaches a preset melting point temperature, the fusible alloy changes from a solid to a liquid state within a preset melting time, causing the current path to be interrupted, and the thermal fuse completely disconnects and cuts off the branch current of the zinc oxide varistor, including: When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid, increasing its fluidity. The internal current path of the thermal fuse is interrupted within the preset melting time, causing the current in the zinc oxide varistor branch to drop from the deteriorated leakage current value to zero. The current in the zinc oxide varistor branch is monitored in real time. When the current in the branch is detected to be zero and the duration exceeds the preset confirmation time, the tripping is completed.

[0012] In conjunction with the first aspect, the eighth implementation of the first aspect of the present invention further includes: The terminal voltage is attenuated to an attenuated voltage by a voltage divider network connected in parallel across the zinc oxide varistor according to a preset voltage division ratio. The attenuated voltage is then compared with a preset reference voltage at the negative input of the voltage comparator. When the zinc oxide varistor deteriorates, causing the attenuation voltage to exceed the preset reference voltage, the voltage comparator outputs a high-level signal to drive the dual-color LED to switch from green to red and energize the relay coil to trigger the normally open contact to close or the normally closed contact to open, outputting a dry contact alarm signal.

[0013] A second aspect of the present invention provides a protector for performing the above-described 1U pluggable maintenance-free power surge protection method.

[0014] Compared with existing technologies, in terms of surge protection, a voltage comparator monitors the voltage at the varistor terminal in real time and triggers clamping and current discharge within a nanosecond response time. Utilizing the avalanche breakdown characteristics of the varistor's grain boundary layer, a low-resistance discharge channel is formed, rapidly discharging the surge current to the protective ground wire. Simultaneously, the residual voltage is clamped below a preset limit, effectively protecting downstream load equipment from overvoltage damage. In terms of safety protection, an NTC thermistor is tightly attached to the varistor's ceramic substrate to collect the core temperature in real time. When the temperature continuously exceeds the warning threshold and the temperature rise rate is abnormal, the varistor is determined to be in a deteriorated state. At this time, a thermal fuse connected in series in the branch circuit receives heat from the MOV through a thermally conductive material and automatically melts when the core temperature reaches the tripping threshold, cutting off the current path of the deteriorated varistor and preventing continuous heating that could cause a fire. This achieves passive fault isolation without external control. In terms of condition monitoring, the voltage at the varistor terminal is detected by a voltage divider resistor network and compared with a reference value. When the voltage deteriorates, the dual-color LED is driven to change from green to red to provide a visual indication. At the same time, a dry contact alarm signal is output to realize remote monitoring, enabling maintenance personnel to promptly detect and replace faulty modules. Attached Figure Description

[0015] 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.

[0016] The structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0017] Figure 1 This is a flowchart illustrating the 1U pluggable maintenance-free power surge protection method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit principle of a 1U pluggable maintenance-free power surge protector. Detailed Implementation

[0018] 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, not all, of the embodiments of the present invention. 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.

[0019] The flowchart shown in the attached diagram is for illustrative purposes only and does not necessarily include all content and operations / steps, nor does it necessarily have to be performed in the order described. For example, some operations / steps can be broken down, combined, or partially merged, so the actual execution order may change depending on the actual situation.

[0020] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items, and all possible combinations, and includes such combinations. See also Figure 1 One embodiment of the 1U pluggable maintenance-free power surge protection method of the present invention includes: Step 100: Monitor the terminal voltage of the zinc oxide varistor in the L-PE branch. When the terminal voltage exceeds the preset start-up voltage threshold, output a clamping and bleed-out start signal. Specifically, a zinc oxide varistor MOV_L is configured in the L-PE branch. Its terminal voltage V_LP is extracted through the device's built-in voltage sampling contact. The sampling contact is connected to the subsequent voltage processing module through a buffer circuit with an input impedance of 12MΩ to ensure that the sampling process does not cause significant current shunting or signal interference to the main bleeder channel of MOV_L. The buffered and amplified V_LP signal is input to the positive input of the high-speed hardware voltage comparator IC_COMP1. Simultaneously, a fixed voltage threshold U_start is preset at the negative input of this comparator. The voltage threshold is set to 700V based on the maximum amplitude of the peak voltage of the power grid and a margin. When the acquired V_LP exceeds 700V, IC_COMP1 generates a high-level output, which is a typical rising-edge pulse with a steep leading edge and stable amplitude. The high-level trigger pulse is input into a set of RC filter networks for noise suppression and spike signal elimination. The RC filter network consists of a 10kΩ current-limiting resistor and a 15pF bypass capacitor. Its time constant is adapted to the trigger criterion, which can effectively filter out interference pulses with a duration of less than 100 nanoseconds, allowing only stable pulses triggered by real surge events to pass through, and outputs a clamping and bleed start signal.

[0022] Step 200: The zinc oxide varistor receives the clamping and discharge start signal, and within a preset response time, the zinc oxide varistor jumps from a high resistance state to a low resistance state, discharging the surge current to the PE ground wire and clamping the residual voltage to below the preset residual voltage limit.

[0023] Specifically, a response path is constructed based on the material properties and nonlinear current-voltage response mechanism of the zinc oxide varistor. When MOV_L receives the clamping and bleed current initiation signal S_trigger from the voltage determination module, its internal ceramic matrix, composed of ZnO grains, exhibits multiple grain boundary barrier structures at the microscopic level. These grain boundary layers have extremely high impedance under normal operating conditions, exhibiting an overall high-resistivity state (resistance value greater than 1GΩ), and cannot conduct large currents. However, when S_trigger indicates the voltage across its terminals... When the voltage exceeds the startup threshold of 700V, the grain boundary barrier rapidly collapses under the influence of the strong electric field and enters an avalanche breakdown state. A large number of charge carriers are excited to cross the barrier, causing a sharp increase in the conductivity inside the MOV. Its overall resistance jumps from high resistance to low resistance (less than 1Ω) within 25 nanoseconds, thus forming a transient low-resistance path between the L-line input terminal and the PE ground wire. The surge current then flows from the L-line through the MOV_L positive terminal, the ZnO ceramic body, the MOV_L negative terminal, and finally to the PE busbar to be discharged into the grounding system, forming a complete discharge loop. During the discharge process, due to the nonlinear resistance characteristics of the MOV, the voltage across its terminals does not rise indefinitely but is clamped within a specific voltage range. The surge event lasts for tens of microseconds. After the current waveform decays to less than 50% of its peak value and gradually returns to zero, the internal temperature of the MOV_L will rise slightly due to current dissipation. However, the potential barrier structure of its grain boundary layer will gradually return to its original high-resistivity state within the recovery time after the surge subsides. The typical recovery time is 50 microseconds. At this time, the leakage channel is disconnected, the MOV regains its insulation characteristics, and the leakage current of the L-PE branch also quickly drops back to the normal level of less than 50 microamps.

[0024] In one specific embodiment, the process of performing step 100 may specifically include the following steps: The terminal voltage of the zinc oxide varistor in the L-PE branch is collected and transmitted to the positive input of the voltage comparator; The voltage comparator compares the terminal voltage with a preset start-up voltage threshold at the negative input terminal. When the terminal voltage is greater than the preset start-up voltage threshold, it outputs a high-level trigger pulse. The high-level trigger pulse is RC filtered to output a clamping and bleed start signal.

[0025] Specifically, the zinc oxide varistor MOV_L in the L-PE branch is used as the monitoring object for the voltage source signal. The voltage V_LP across its terminals is taken as the measured input. The V_LP signal is extracted through the voltage sampling contact reserved inside the varistor and isolated and amplified using a high-impedance buffer circuit with an input impedance of 12MΩ. This ensures that the sampling channel does not cause any perceptible shunt disturbance to the main leakage path, while maintaining the stability of the signal source potential. The output of the buffer circuit is connected to the positive input of the voltage comparator IC_COMP1, while the negative input of the voltage comparator is connected to a reference voltage source, set to 700V. If the actual voltage V_LP across MOV_L exceeds 700V, IC_COMP1 outputs a high-level pulse. This high-level pulse has an extremely fast rise edge and high amplitude; its logic level indicates that the surge event has been confirmed and serves as the trigger for the clamping leakage logic. The high-level trigger pulse is processed by an RC filter network. This network consists of a 10kΩ current-limiting resistor and a 15pF bypass capacitor connected in series and parallel. Its time constant has been adjusted to ensure that only stable signals with a duration greater than 100 nanoseconds are allowed to pass through. Transient interference pulses such as electromagnetic interference, power supply glitches, and arc discharges are effectively suppressed and filtered out by the RC network, improving the robustness and accuracy of the overall triggering system. The filtered signal is output as the clamping current discharge start signal S_trigger, transmitted to the surge discharge control path, driving MOV_L into a low-resistance conduction state, thus guiding the discharge of surge current and providing front-end protection for the system.

[0026] In one specific embodiment, the process of performing RC filtering on the high-level trigger pulse and outputting a clamping and bleed start signal can specifically include the following steps: The high-level trigger pulse is input to the RC filter circuit to filter out interference spikes in the high-level trigger pulse whose duration is less than the preset pulse width threshold, and obtain the filtered pulse signal. When the duration is greater than the preset pulse width threshold, the clamping and bleed current start signal is output and the trigger time is latched.

[0027] Specifically, a high-level trigger pulse signal is input into a set of RC filter circuits. The RC filter circuit consists of a series current-limiting resistor with a resistance of 10kΩ and a parallel bypass capacitor with a capacitance of 15pF. Its filtering time constant determines the response speed to the signal leading edge and the ability to hold the trailing edge. This makes high-frequency spike voltage pulses with a duration of less than 100 nanoseconds regarded as noise components and rapidly attenuated during RC integration, preventing the output voltage from rising to the logic high-level judgment threshold. This effectively shields interference sources such as electromagnetic disturbances, transient reflections, and device switching glitches. When the duration of the input high-level pulse exceeds 100 nanoseconds, the capacitor will accumulate sufficient charge during the charging process, and the output voltage will rise to the high-level input judgment threshold of the trigger logic gate or Schmitt trigger, forming a filtered pulse signal with stable amplitude, clean edges, and sufficient time width. The filtered pulse signal is used as the clamping and discharge start signal S_trigger and input to the MOV control logic module to drive the zinc oxide varistor into a low-resistance conduction state to carry out the establishment of the surge current discharge path. At the same time, the rising edge of the S_trigger trigger is input to the timestamp latch module. The timestamp latch module captures the absolute time point t0 of the trigger based on a high-speed clock source (such as a 100MHz crystal oscillator) and stores the trigger time in the register.

[0028] In one specific embodiment, the process of performing step 200 may specifically include the following steps: The zinc oxide varistor receives the clamping and bleed-out start signal; The grain boundary layer inside the zinc oxide varistor undergoes avalanche breakdown under the action of the clamping discharge start signal. The resistance of the zinc oxide varistor jumps from a high resistance state to a low resistance state within a preset response time, forming a discharge channel from the L line to the PE ground line, allowing the surge current to flow through the zinc oxide varistor to the PE ground line. The zinc oxide varistor generates a clamping voltage during the surge current carrying process. The clamping voltage is less than the preset residual voltage limit. After the surge current decays, the resistance of the zinc oxide varistor rises back to the high resistance state within the preset recovery time.

[0029] Specifically, after the current-stage voltage determination module completes surge identification and outputs a valid clamping and bleed current initiation signal S_trigger after RC filtering, the MOV device is considered to be in the triggered state. Its voltage V_LP is greater than 700V and meets the time-width characteristics of the real surge waveform. At this time, although the clamping and bleed current initiation signal is a logic-level output, MOV_L does not rely on an external electronic control switch to conduct. Instead, it completes the conductance state transition under the physical drive of voltage increase through its own material properties. At the microscopic level, the MOV is composed of a large number of ZnO grains. At the grain boundaries, there are potential barriers that restrict electron flow under normal conditions, causing the MOV to exhibit extremely high impedance (typically greater than 1 GΩ). However, when the electric field strength reaches the breakdown condition, i.e., V_LP exceeds the breakdown threshold, the barrier structure collapses rapidly due to electron avalanche breakdown, resulting in a surge in the carrier density between the grain boundary layers. This causes the overall resistance of the varistor to jump from a high-resistance state to a low-resistance state (less than 1 Ω) in a very short time (typical response time is 25 nanoseconds). Macroscopically, this manifests as an instantaneous low-resistance leakage channel formed between the L line and the PE ground line. The surge current I_surge flows from the L input terminal through the positive terminal of MOV_L into the ZnO ceramic body along the low-resistance leakage path, and then leaks from the negative terminal into the PE busbar and finally into the ground system, achieving safe release of high-energy transients. At the same time, due to the obvious nonlinear voltage-current characteristics of MOV, its two ends do not show a linear voltage drop during conduction, but are stably clamped within a certain voltage range. According to the device parameters, when the surge current is 10kA, the MOV clamping voltage V_clamp is 1150V, and when the current increases to 20kA, V_clamp rises slightly to 1280V, but is always controlled within the preset residual voltage limit of 1.2kV, thus effectively protecting downstream equipment from overvoltage impact. As the surge event enters the decay phase, the surge current decreases rapidly, and the voltage across the MOV drops accordingly. When V_LP drops below the breakdown threshold, the grain boundary barrier structure begins to recover, the electron migration rate decreases, and the overall conductivity weakens, causing the MOV resistance to gradually rise back to the initial high resistance state within 50 microseconds. The leakage channel closes, and the leakage current drops back to below tens of microamps.

[0030] In this embodiment, before the avalanche breakdown of the grain boundary layer inside the zinc oxide varistor, a voltage gradient prediction and graded discharge initiation process is also included: a low-start-voltage varistor and a standard-start-voltage varistor are configured in parallel in the L-PE branch. The start-up voltage threshold of the low-start-voltage varistor is lower than that of the standard-start-voltage varistor. The low-start-voltage varistor is used to quickly respond to small surges, while the standard-start-voltage varistor, a zinc oxide varistor, is used to carry large surges. The voltage gradient detection circuit performs a differential operation on the terminal voltage to obtain the voltage rise rate. The voltage gradient detection circuit includes a differentiator and a comparator. When the voltage rise rate exceeds a preset gradient threshold, it is determined that a surge event is about to occur, and a pre-trigger signal is output to reduce the triggering delay of the low-start-voltage varistor. When the terminal voltage rises to the threshold voltage of the low-start-voltage varistor, the low-start-voltage varistor preferentially turns on to establish a preliminary current-discharging channel to release the leading-edge surge current, clamping the terminal voltage at the first clamping voltage level, which is lower than the threshold voltage of the standard-start-voltage varistor. When the surge current amplitude continues to increase, causing the terminal voltage to exceed the first clamping voltage level and rise to the threshold voltage of the standard-start-voltage varistor, the standard-start-voltage varistor turns on and discharges current in parallel with the low-start-voltage varistor, clamping the terminal voltage at the second clamping voltage level, which is a preset residual voltage limit. Through the graded coordinated operation of the low-start-voltage varistor and the standard-start-voltage varistor, the overall clamping response time is reduced and the energy stress of individual varistors is distributed, extending their service life.

[0031] In one specific embodiment, the process of the zinc oxide varistor generating a clamping voltage during the surge current carrying process, wherein the clamping voltage is less than a preset residual voltage limit, and the resistance of the zinc oxide varistor recovering to a high resistance state within a preset recovery time after the surge current decays, can specifically include the following steps: Zinc oxide varistors carry surge current in a low-resistance state. The two ends of the zinc oxide varistor generate a clamping voltage and absorb surge energy, which is converted into heat and deposited in the ceramic matrix, causing the core temperature to rise instantaneously. When the surge current decays to below the preset current threshold, the terminal voltage drops, and the grain boundary barrier of the zinc oxide varistor recovers, causing the resistance to rise back to a high resistance state within a preset recovery time.

[0032] Specifically, when the MOV device receives a surge trigger signal and its voltage exceeds the start-up threshold, its internal ZnO ceramic structure rapidly transitions from a high-resistivity state to a low-resistivity state. The MOV enters conduction mode and establishes a discharge path between the L line and the PE ground line in a very short time. At this time, the surge current I_surge flows into the device in the range of tens of amperes or even tens of thousands of amperes. Due to the nonlinear volt-ampere characteristics of the MOV, its voltage will not rise indefinitely under high current conditions, but will be clamped below a certain level, always maintained within a preset residual voltage limit of no more than 1.2kV. The product of the clamping voltage and the surge current constitutes the instantaneous power consumption P_MOV = V_clamp × I_surge. During the surge, the instantaneous power consumption is deposited in the ZnO ceramic matrix as instantaneous heat energy, forming a significant temperature rise effect. Taking a 20kA / 8μs surge as an example, the corresponding absorbed energy can reach 102.4J. This energy causes the MOV core temperature to rise rapidly by several degrees within a few microseconds. The temperature rise is related to the MOV ceramic mass and specific heat capacity, with a typical instantaneous temperature rise of 4.6℃. As the surge current decays to below the preset current threshold, the voltage V_LP across the MOV drops below the grain boundary recovery threshold. The grain boundary barrier structure inside the device begins to rebuild, hindering the carrier migration path, resulting in a rapid decrease in the conduction current. The resistance exhibited by the device then rises. Within the preset recovery time window (typically 50 microseconds), the MOV recovers to a high-resistivity state, and its leakage current drops to a normal value of less than 50 microamps. The leakage channel is automatically cut off. This closed-loop behavior relies on the intrinsic material properties of the device and does not require external control. This ensures that the system has self-recovery capability and can continuously cope with repeated surge impacts. During the surge, it can effectively absorb electromagnetic energy and convert it into heat energy, and after the surge ends, it promptly returns to a high-resistivity state to prevent abnormal leakage.

[0033] In one specific embodiment, the following steps are also included: The core temperature is collected by an NTC thermistor attached to the back of the ceramic substrate in the zinc oxide varistor, and the voltage signal of the NTC thermistor is converted into the core temperature. When the core temperature continues for a preset duration exceeding the preset warning temperature threshold and the temperature rise rate exceeds the preset temperature rise rate threshold, a degradation flag is output.

[0034] Specifically, an NTC thermistor RT_sense is installed at the center of the back of the ceramic substrate of the MOV_L varistor. Thermal grease ensures tight adhesion between the thermistor and the MOV core. The thermal interface material has a low thermal resistance of 0.45℃ / W, allowing for rapid and accurate conduction of internal MOV temperature rise to the NTC, thus ensuring consistent and real-time temperature response. For example, an NTC device with a B value of 3950K and a nominal resistance of 10kΩ at 25℃ is selected. Its resistance-temperature relationship follows an exponential function. By connecting an excitation source providing a constant 1mA current, a measurable voltage signal V_NTC is generated across the entire temperature range. This measurable voltage signal is input to a 12-bit resolution ADC module for periodic sampling at a frequency of 10Hz. The digital signal output from the ADC is then input to a temperature calculation module. Based on a preset NTC resistance value table or an exponential function expression, the module converts the voltage signal into a real-time core temperature T_core, updating the temperature value every 100ms and writing it to a buffer for subsequent determination. When an MOV device is subjected to repeated surges for a long time and grain boundary degradation occurs, its leakage current gradually increases, leading to enhanced device heating. The core temperature will show a continuous upward trend. To identify this trend, the temperature monitoring logic sets dual criteria: first, whether the absolute temperature value T_core is continuously higher than the preset warning temperature threshold (e.g., 95℃); second, whether the temperature rise rate dT / dt is higher than the temperature rise rate threshold (e.g., 0.8℃ / min). The temperature rise rate is calculated by linearly fitting five consecutive sampling points within a sliding time window to estimate the slope of the temperature change. When both criteria are met simultaneously and the duration exceeds the preset time (e.g., 300 seconds), it is determined that the MOV has entered the degradation range, i.e., the degradation flag Flag_warn = 1 is output.

[0035] Before collecting the core temperature, a 1U compact space heat dissipation optimization process is included: A zinc oxide varistor is laid flat on the surface of an aluminum heat sink substrate; the available vertical space of the heat sink substrate is calculated based on the 1U height limit, which is the standard 1U height minus the difference between the zinc oxide varistor thickness and the casing thickness; longitudinal heat dissipation fins are processed on the surface of the heat sink substrate; the optimal fin spacing is determined based on the relationship between the fin spacing and the natural convection heat dissipation efficiency, maximizing the heat dissipation power per unit volume; the heat dissipation fins increase the heat dissipation area and reduce the convective thermal resistance between the heat sink substrate and the environment; and thermal interface materials are used to fill... The micro-air gap between the zinc oxide varistor ceramic substrate and the heat dissipation substrate is filled, and the thermal conductivity of the thermal interface material is greater than a preset thermal conductivity threshold, so that the contact thermal resistance from the zinc oxide varistor to the heat dissipation substrate is less than a preset contact thermal resistance limit. The total thermal resistance from the zinc oxide varistor core to the environment is calculated as the sum of the contact thermal resistance, the thermal conductivity of the heat dissipation substrate, and the convection thermal resistance. Under the condition that the continuous leakage current of the zinc oxide varistor reaches the degradation current threshold, the steady-state temperature rise is calculated based on the continuous leakage power consumption and the total thermal resistance. The temperature margin between the steady-state temperature rise and the preset tripping temperature threshold is verified to be greater than the preset margin threshold, ensuring reliable triggering of the temperature control self-tripping.

[0036] Before outputting the degradation indicator, a degradation degree quantification assessment process is included: The branch current is collected in real time using a precision sampling resistor connected in series with the zinc oxide varistor branch. This branch current is converted into a voltage signal, amplified, and the leakage current monitoring value is obtained. Simultaneously, core temperature data and leakage current monitoring values ​​are recorded to construct a time-series data sequence. A sliding window analysis is performed on the time-series data sequence. The leakage current growth rate within a preset time window is calculated as the difference between the current leakage current and the initial leakage current divided by the operating time. The correlation coefficient between temperature and leakage current is calculated as the ratio of the core temperature change to the leakage current change. When the correlation coefficient exceeds a preset correlation threshold, it is determined that the temperature rise is caused by degradation leakage rather than surge impact. The cumulative number of surge impacts is counted based on the latched surge trigger times to obtain... The cumulative absorbed energy is calculated as the sum of the absorbed energy of each surge. A degradation assessment function is established, which takes the leakage current growth rate, temperature rise rate, and cumulative absorbed energy as input parameters and calculates the degradation degree assessment value through weighted summation. The degradation level is divided according to the degradation degree assessment value. When the degradation degree assessment value is in the first assessment range, a mild degradation warning signal is output, suggesting that the module be replaced within the preset maintenance cycle. When the degradation degree assessment value is in the second assessment range, a moderate degradation alarm signal is output, suggesting that the module be replaced within the preset emergency cycle. When the degradation degree assessment value exceeds the third assessment threshold, a degradation flag is output to trigger the temperature control self-tripping process. The first assessment range, the second assessment range, and the third assessment threshold increase sequentially to form a graded warning mechanism.

[0037] In one specific embodiment, the following steps are also included: The thermal fuse connected in series with the zinc oxide varistor branch is thermally coupled to the ceramic substrate of the zinc oxide varistor through a thermally conductive material. When the core temperature reaches the preset tripping temperature threshold, the heat is transferred to the thermal fuse through the thermally conductive material, causing the internal fusible alloy temperature to rise. When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid within the preset melting time, causing the current path to be interrupted. The thermal fuse then completely disconnects and cuts off the branch current of the zinc oxide varistor.

[0038] Specifically, a thermal fuse TF_L, using a Sn-Bi eutectic alloy as the sensing element, is connected in series in the bleed branch of the MOV_L, with its ceramic package bottom tightly attached to the surface of the zinc oxide varistor ceramic substrate. A layer of thermally conductive silicone grease with a thickness of approximately 0.2 mm and a thermal conductivity of 5.0 W / (m·K) is applied between them to create a stable thermal coupling interface. This structure allows the heat generated by the MOV core during degradation to be efficiently conducted to the fusible alloy inside the TF_L. The melting point of the Sn-Bi alloy used in the thermal fuse is controlled at 115℃±3℃, and its heat dissipation is limited by the ceramic shell, ensuring that its temperature rise is primarily controlled by the thermal state of the MOV core. When the MOV continuously experiences excessive leakage power in a degraded state, its core temperature gradually rises. When it reaches or exceeds the set tripping temperature threshold of 113℃, heat is transferred to the TF_L through the thermal coupling interface with a thermal resistance of only 0.001℃ / W, causing the internal alloy temperature to rapidly rise to the melting point range. As the temperature rises further, the alloy changes from a solid to a liquid state. This morphological change disrupts the original metal conductive structure, causing the branch current flowing through TF_L to lose continuity. As a result, the MOV branch current drops from milliampere-level leakage current to zero within a melting time of 3 to 8 seconds, achieving electrical isolation and fault disconnection after MOV deterioration.

[0039] In one specific embodiment, the process of executing the step whereby when the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from a solid to a liquid state within a preset melting time, causing the current path to be interrupted, and the thermal fuse completely disconnects and cuts off the branch current of the zinc oxide varistor, can specifically include the following steps: When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid, increasing its fluidity. The internal current path of the thermal fuse is interrupted within the preset melting time, causing the current in the zinc oxide varistor branch to drop from the deteriorated leakage current value to zero. The current in the zinc oxide varistor branch is monitored in real time. When the branch current is detected to be zero and the duration exceeds the preset confirmation time, the tripping is completed.

[0040] Specifically, a thermal fuse TF_L is connected in series in the MOV_L bleeder branch. The thermal fuse is encapsulated with a low-melting-point Sn-Bi eutectic alloy with a melting point of 115℃±3℃. It is tightly thermally coupled to the MOV_L ceramic substrate through thermally conductive silicone grease, allowing excess heat generated by the MOV core under thermal degradation to be quickly conducted to the fuse. When the MOV experiences grain boundary degradation after repeated surge impacts, causing its leakage current I_leak to increase to the milliampere level, the device's continuous power consumption increases. Without forced cooling, the MOV core temperature T_core will continue to rise above 113℃ and approach or exceed the melting point of the Sn-Bi alloy. At this point, the alloy begins a phase transition from solid to liquid, rapidly increasing its fluidity. The filling structure is reconstructed, disrupting the original metallic continuity. This causes the previously conductive current path to gradually lose mechanical stability and completely disconnect within a 3-8 second melting time window. Consequently, the degraded leakage current flowing through MOV_L drops sharply from 2mA or higher to 0A, achieving electrical isolation. To confirm the tripping completion status, a current sampling circuit is integrated into the MOV branch. A high-sensitivity Hall sensor is used to monitor the current in the TF_L series circuit in real time. The sampling resolution is set to 1mA, and the update cycle does not exceed 100ms. When the sampling result stably outputs 0A for several consecutive cycles, and the current is zero for more than the preset confirmation time (e.g., 1 second), it is determined that the thermal fuse has completely disconnected, the MOV branch current has been completely cut off, and the tripping completion flag Flag_trip = 1 is output.

[0041] In one specific embodiment, the following steps are also included: The terminal voltage is attenuated to an attenuated voltage by a voltage divider network connected in parallel across the zinc oxide varistor according to a preset voltage division ratio. The attenuated voltage is then compared with a preset reference voltage at the negative input of the voltage comparator. When the zinc oxide varistor deteriorates and the attenuation voltage exceeds the preset reference voltage, the voltage comparator outputs a high-level signal to drive the dual-color LED to switch from green to red and energize the relay coil to trigger the normally open contact to close or the normally closed contact to open, outputting a dry contact alarm signal.

[0042] Specifically, a high-impedance voltage divider resistor network is constructed in parallel across the zinc oxide varistor. The voltage divider resistor network consists of a pull-up resistor and a pull-down resistor connected in series. One end of the pull-up resistor is connected to the L-line side of the MOV, and the other end is connected to the pull-down resistor, which is then connected to the PE ground line side. The connection point between the two forms a voltage sampling node. By appropriately setting the resistor ratio, such as R_up being 1MΩ and R_down being 100kΩ, a voltage division ratio of 10:1 is achieved, thereby attenuating the MOV terminal voltage V_mov to V_detect = V_mov × R_down / (R_up + R_down). This attenuated voltage serves as the positive input signal of the comparator. Simultaneously, a precision reference voltage V_ref is introduced to the negative input of the comparator. The reference voltage is provided by a regulated power supply, and its value corresponds to V_detect under normal MOV voltage conditions. For example, when the MOV is subjected to a 385V power frequency voltage for a long period, V_detect corresponds to 38.5V according to the 10:1 ratio. Therefore, V_ref is set to a value slightly higher than this, such as 40V, to build a fault detection margin. When the MOV's grain boundary structure deteriorates, causing its leakage current to rise and its voltage drop to rise abnormally, resulting in V_mov increasing to 425V or even higher, the voltage-divided V_detect also increases accordingly and exceeds V_ref. The comparator detects that the positive input is higher than the negative input and outputs a high-level logic signal. The high-level output directly drives the dual-color LED indicator with a common cathode structure. The green LED anode is connected to the inverting signal path, while the red LED anode is connected to the direct output path. Therefore, when the comparator output is high, the green LED turns off and the red LED turns on, providing a visual indication of the fault status on the front panel. On the other hand, the high level is simultaneously applied to the relay coil. The relay is energized and closes, causing the normally open contact to close and the normally closed contact to open. A passive alarm channel is formed through the dry contact output, which is suitable for remote input interface connection to external monitoring systems. It supports remote alarm, alarm collection, and maintenance prompts for the module's deterioration status.

[0043] This includes a 1U module hot-swap protection process: During the insertion of the quick-connect terminal of the 1U module into the female copper busbar slot, a displacement sensor detects the insertion depth of the quick-connect terminal in real time. The displacement sensor outputs a displacement signal proportional to the insertion depth, which is compared with a preset insertion depth threshold sequence. The preset insertion depth threshold sequence includes three threshold points: initial contact depth, partial insertion depth, and full insertion depth. When the insertion depth reaches the initial contact depth, the spring of the quick-connect terminal begins to contact the female copper busbar. A four-wire measurement circuit monitors the contact resistance between the quick-connect terminal and the female copper busbar in real time. The four-wire measurement circuit eliminates the influence of lead resistance through independent current injection terminals and voltage detection terminals. When the contact resistance drops from the open circuit state to within the preset contact resistance range, the electrical connection is confirmed. When the insertion depth reaches... As the insertion depth increases, the spring preload gradually increases. The compression state of the spring is determined by the rate of change of contact resistance. The rate of change of contact resistance as the insertion depth increases reflects the growth rate of the contact force. When the rate of change is less than a preset threshold, the spring compression is considered to be obstructed, and an insertion abnormality alarm is output. When the insertion depth reaches the full insertion depth, the locking latch of the guide rail automatically engages. The engagement status of the locking latch is detected by a Hall sensor. The Hall sensor senses the change in the magnetic field of the magnet inside the latch and outputs an engagement confirmation signal. At the same time, it verifies that the contact resistance is stable within the preset stable resistance range and the duration exceeds the preset stable duration. When the engagement confirmation signal is valid and the contact resistance meets the stability condition, an installation completion flag is output, triggering the initialization self-test process of the new module to verify the voltage at the zinc oxide varistor terminal, the core temperature, and the working status of the alarm circuit.

[0044] The above describes the 1U pluggable maintenance-free power surge protection method in the embodiments of the present invention. The following describes the protector in the embodiments of the present invention, which is used to perform the above-described 1U pluggable maintenance-free power surge protection method.

[0045] In this embodiment, the disassembly of the faulty module does not require disconnecting the main power supply of the power distribution system and is performed while the power is on. The specific steps are as follows: The maintenance personnel stand in front of the cabinet, confirm the location of the faulty module by observing the red LED on the 1U panel, and hold the handles on both sides of the front panel of the module (handle width 120mm, height 15mm, surface anti-slip texture treatment) and apply outward pulling force. This pulling force first acts on the unlocking mechanism of the quick-connect terminal. The quick-connect terminal adopts a spring-type design. Each L, N, PE terminal is equipped with a copper alloy spring (material C17200, elastic modulus 130GPa, thickness 0.8mm). In the pre-tightened state, the spring is pressed against the corresponding female copper busbar. The contact pressure is generated by the pre-tightened displacement of the spring. According to Hooke's law, the equivalent elastic coefficient of the spring is... When the pulling force exceeds 30N, the locking latch of the quick-connect terminal (located at the root of the terminal, latch angle 15°) is unlocked, the contact pressure between the spring and the female copper busbar is overcome, and the terminal begins to withdraw from the busbar slot. The withdrawal stroke is controlled manually throughout the entire withdrawal process. After the terminal is completely withdrawn, continue pulling the panel to disengage the guide rail latch at the rear of the module. The guide rail latch adopts an L-shaped hook structure. The hook engages in the groove (5mm deep) of the 1U rack guide rail. Under the action of pulling force, the hook rotates around the fulcrum and then disengages from the groove. At this point, the module is completely detached from the rack. The installation of the new module is the reverse of the disassembly process: The maintenance personnel hold the new module (which has been parameter-calibrated before leaving the factory), align the guide rail latch at the rear of the module with the groove on the rack guide rail, and push the module inward until the latch hooks are inserted into the groove to a depth >4mm. Then, continue pushing the front of the module until the quick-connect terminals on the front panel are aligned with the female copper busbar slot. The guide bevel of the quick-connect terminal guides the terminal into the slot. During the insertion stroke, the spring is compressed by the busbar, generating a pre-tightening force. When the terminal insertion depth reaches 10mm, the locking latch automatically engages, at which point the quick-connect terminal and the busbar form a reliable electrical connection. After installation, the new module automatically enters the working state without manual parameter configuration or calibration. The module's internal initialization circuit (reset chip monitors power-on) enables the surge protector to operate from degradation detection, automatic tripping, fault alarm to module replacement, forming a complete maintenance-free process.

[0046] Figure 2This is a circuit diagram of a 1U pluggable maintenance-free power surge protector. The main current leakage path consists of the L-line input terminal, quick-connect terminal, zinc oxide varistor MOV, thermal fuse TF, and PE protective ground line. The thick black line indicates the high current leakage path. In the voltage detection circuit, the blue dashed line represents the voltage signal from the MOV sampling terminal, which is attenuated to the detection voltage by a voltage divider network composed of pull-up resistor R_up and pull-down resistor R_down at a ratio of 1:11. The red dot marks the detection node. In the alarm output circuit, the voltage comparator COMP compares the detection voltage with the reference voltage V_ref. When MOV deterioration causes the detection voltage to exceed the reference value, it drives the dual-color LED to change from green to red and triggers the relay to output a dry contact alarm signal. In the temperature control self-tripping monitoring circuit, the red dashed line represents the temperature signal collected by the NTC thermistor, which is converted by the ADC and sent to the temperature judgment module. When the core temperature continuously exceeds the 95℃ warning threshold and the temperature rise rate exceeds 0.8℃ / min, a deterioration flag is output. The thick red dashed line indicates that the heat generated by the MOV is transferred to the TF through the heat conduction path. When the core temperature reaches the 110℃ tripping threshold, the fusible alloy inside the TF heats up to the melting point of 115℃ and automatically melts and cuts off the branch current, realizing temperature-controlled self-tripping protection.

[0047] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0048] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause an electronic device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0049] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for surge protection of a 1U pluggable maintenance-free power supply, characterized in that, include: Monitor the terminal voltage of the zinc oxide varistor in the L-PE branch, and when the terminal voltage exceeds the preset start-up voltage threshold, output a clamping and bleed-out start signal; The zinc oxide varistor receives the clamping and discharge start signal and, within a preset response time, transitions from a high-resistance state to a low-resistance state, discharging the surge current to the PE ground wire and clamping the residual voltage below a preset residual voltage limit.

2. The 1U pluggable maintenance-free power surge protection method according to claim 1, characterized in that, Monitor the terminal voltage of the zinc oxide varistor in the L-PE branch. When the terminal voltage exceeds a preset start-up voltage threshold, output a clamping discharge start signal, including: The terminal voltage of the zinc oxide varistor in the L-PE branch is collected and transmitted to the positive input of the voltage comparator; The voltage comparator compares the terminal voltage with a preset start-up voltage threshold at the negative input terminal. When the terminal voltage is greater than the preset start-up voltage threshold, it outputs a high-level trigger pulse. The high-level trigger pulse is subjected to RC filtering to output a clamping and bleed start signal.

3. The 1U pluggable maintenance-free power surge protection method according to claim 2, characterized in that, The high-level trigger pulse is subjected to RC filtering to output a clamping and bleed start signal, including: The high-level trigger pulse is input into an RC filter circuit to filter out interference spikes in the high-level trigger pulse whose duration is less than a preset pulse width threshold, thereby obtaining a filtered pulse signal. When the duration is greater than the preset pulse width threshold, a clamping and bleed current start signal is output and the trigger time is latched.

4. The 1U pluggable maintenance-free power surge protection method according to claim 3, characterized in that, The zinc oxide varistor receives the clamping and bleed current initiation signal, and within a preset response time, transitions from a high-resistance state to a low-resistance state to discharge the surge current to the PE ground wire and clamp the residual voltage below a preset residual voltage limit, including: The zinc oxide varistor receives the clamping and bleed start signal; The grain boundary layer inside the zinc oxide varistor undergoes avalanche breakdown under the action of the clamping discharge start signal. The resistance of the zinc oxide varistor jumps from a high resistance state to a low resistance state within a preset response time, forming a discharge channel from the L line to the PE ground line, allowing the surge current to flow to the PE ground line through the zinc oxide varistor. The zinc oxide varistor generates a clamping voltage during the surge current carrying process. The clamping voltage is less than a preset residual voltage limit. After the surge current decays, the resistance of the zinc oxide varistor rises back to a high resistance state within a preset recovery time.

5. The 1U pluggable maintenance-free power surge protection method according to claim 4, characterized in that, The zinc oxide varistor generates a clamping voltage during surge current carrying. This clamping voltage is less than a preset residual voltage limit. After the surge current decays, the resistance of the zinc oxide varistor recovers to a high resistance state within a preset recovery time, including: The zinc oxide varistor carries surge current in a low-resistance state. The two ends of the zinc oxide varistor generate clamping voltage and absorb surge energy, which is converted into heat and deposited in the ceramic matrix, causing the core temperature to rise instantaneously. When the surge current decays to below a preset current threshold, the terminal voltage drops, and the grain boundary barrier of the zinc oxide varistor recovers, causing the resistance to rise back to a high resistance state within a preset recovery time.

6. The 1U pluggable maintenance-free power surge protection method according to claim 1, characterized in that, Also includes: The core temperature is collected by an NTC thermistor attached to the back of the ceramic substrate in the zinc oxide varistor, and the voltage signal of the NTC thermistor is converted into the core temperature. When the core temperature continues for a preset duration exceeding a preset warning temperature threshold and the temperature rise rate exceeds a preset temperature rise rate threshold, a degradation flag is output.

7. The 1U pluggable maintenance-free power surge protection method according to claim 6, characterized in that, Also includes: The thermal fuse connected in series in the zinc oxide varistor branch is thermally coupled to the ceramic substrate of the zinc oxide varistor through a thermally conductive material. When the core temperature reaches a preset tripping temperature threshold, heat is transferred to the thermal fuse through the thermally conductive material, causing the internal fusible alloy temperature to rise. When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid within the preset melting time, causing the current path to be interrupted, and the thermal fuse completely disconnects and cuts off the branch current of the zinc oxide varistor.

8. The 1U pluggable maintenance-free power surge protection method according to claim 7, characterized in that, When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from a solid to a liquid state within a preset melting time, causing the current path to be interrupted. The thermal fuse completely disconnects and cuts off the branch current of the zinc oxide varistor, including: When the temperature of the fusible alloy reaches the preset melting point temperature, the fusible alloy changes from solid to liquid, increasing its fluidity. The internal current path of the thermal fuse is interrupted within the preset melting time, causing the current in the zinc oxide varistor branch to drop from the deteriorated leakage current value to zero. The current in the zinc oxide varistor branch is monitored in real time. When the current in the branch is detected to be zero and the duration exceeds the preset confirmation time, the tripping is completed.

9. The 1U pluggable maintenance-free power surge protection method according to claim 8, characterized in that, Also includes: The terminal voltage is attenuated to an attenuated voltage by a voltage divider network connected in parallel across the zinc oxide varistor according to a preset voltage division ratio. The attenuated voltage is then compared with a preset reference voltage at the negative input of the voltage comparator. When the zinc oxide varistor deteriorates, causing the attenuation voltage to exceed the preset reference voltage, the voltage comparator outputs a high-level signal to drive the dual-color LED to switch from green to red and energize the relay coil to trigger the normally open contact to close or the normally closed contact to open, outputting a dry contact alarm signal.

10. A protector, characterized in that, Used to perform the 1U pluggable maintenance-free power surge protection method as described in any one of claims 1-9.

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