Overload protector and power device

Abstract

The application is suitable for the technical field of lightning protection, and provides an overload protector and a power device, the overload protector is used for being connected between two poles of a power supply circuit, and there is no thermal coupling between the overload protector and a protected pressure-sensitive resistor; the overload protector comprises an over-temperature tripping device, an AC / DC heating module and a high-voltage pulse bypass module, the over-temperature tripping device is thermally coupled with the AC / DC heating module, when a power voltage fluctuation exceeds a DC operating voltage of the protected pressure-sensitive resistor, or the operating voltage of the protected pressure-sensitive resistor is lowered due to degradation and is lower than a peak voltage of a power grid, the current flows through the over-temperature tripping device and the AC / DC heating module in series with the protected pressure-sensitive resistor at the same time, so that the AC / DC heating module generates temperature rise, when the temperature of the AC / DC heating module reaches an operating temperature of the over-temperature tripping device, the over-temperature tripping device generates operation separation, and the overload protector is disconnected from the power supply, so that the protected pressure-sensitive resistor is also disconnected from the power supply.

Description

Technical Field

[0001] This application belongs to the field of lightning protection technology, and in particular relates to an overload protector and power equipment. Background Technology

[0002] The industry standard for surge protectors, "Low-voltage surge protectors IEC61643-11_2011," clearly stipulates in Clause 5.12, "Failure Modes of SPDs," that surge protectors must be capable of operating in two failure modes: "open circuit" and "short circuit." Open-circuit failure type SPDs (surge protective devices) must be equipped with an over-temperature tripping mechanism, while short-circuit failure type SPDs must be equipped with a thermal short-circuit mechanism.

[0003] Traditional SPDs or TMOVs (Thermally Protected Metal Oxide Varistors) have zinc oxide varistors (MOVs) connected in series in their discharge circuits. If a tunnel burn-through occurs and the device cannot be quickly disconnected from the power grid, it will pose a serious safety risk. Utility Model Content

[0004] The purpose of this application is to provide an overload protector and power equipment that aims to solve the problem that if the varistor of a traditional voltage-limiting surge protector cannot be quickly disconnected from the power grid after tunnel burn-through, it will pose a serious safety risk.

[0005] A first aspect of this application provides an overload protector, which is used to connect at least two terminals of a power supply to a protected varistor; there is no thermal coupling between the overload protector and the protected varistor; the overload protector includes an over-temperature trip unit, an AC / DC heating module, and a high-voltage pulse bypass module, the high-voltage pulse bypass module being connected in parallel across the two ends of the AC / DC heating module, the over-temperature trip unit being connected in series with the heating module, and the over-temperature trip unit being thermally coupled to the AC / DC heating module; the AC / DC heating module has electrothermal characteristics, and when its temperature rises to the operating temperature of the over-temperature trip unit under the action of AC / DC current, it triggers the over-temperature trip unit to trip and disconnect, cutting off the electrical connection between the overload protector and the power supply.

[0006] In some embodiments, the AC / DC heating module includes a current limiting element and a heating element, wherein the current limiting element and the heating element are connected in series.

[0007] In some embodiments, the current limiting element is welded back-to-back with the heating element, or the current limiting element and the heating element are spaced apart and separately disposed.

[0008] In some embodiments, the heating element includes a varistor valve or a thermistor valve; The current limiting element includes a positive temperature coefficient thermistor, the Curie temperature of which is higher than the operating temperature of the over-temperature trip unit; or the current limiting element includes a fixed resistor.

[0009] In some embodiments, the heating element includes a varistor valve, the varistor valve having a higher rate of temperature rise than the protected varistor.

[0010] In some embodiments, the over-temperature trip unit includes a movable metal elastic electrode at one end, the end of which is soldered to the surface electrode of the heating element by low-temperature solder, and the first end of which is used to connect to the protected varistor or the terminal of the power supply; the melting point temperature of the low-temperature solder corresponds to the operating temperature of the over-temperature trip unit.

[0011] In some embodiments, the AC / DC heating module and the high-voltage pulse bypass module form a core module, and the over-temperature trip unit further includes: The housing has a welding window, a connection position, and a separation position, and the core module and the metal elastic electrode are mounted on the housing; The remote signaling switch includes two remote signaling switch contacts mounted on the housing; An arc-extinguishing slider and a pull-out spring are provided, the pull-out spring being movably mounted on a sliding guide rail of the housing; the metal elastic electrode includes a retaining section connected between an end and a beginning, the beginning of the metal elastic electrode extending to the outside of the housing, the retaining section being located outside the arc-extinguishing slider, and the end of the metal elastic electrode being soldered to the surface electrode of the heating element with low-temperature solder through the welding window, such that the retaining section holds the arc-extinguishing slider in the connection position and causes the arc-extinguishing slider to press against the remote signaling switch, thereby bringing the two remote signaling switch contacts into contact; and The pull-out spring is used to generate an elastic restoring force to drive the arc-extinguishing slider to move toward the separation position, pull the arc-extinguishing slider to reach and cover the welding window, so as to be placed between the surface electrode of the heating element and the end of the metal elastic electrode, and to separate the two remote signaling switch contacts.

[0012] In some embodiments, there are two over-temperature trip units, namely a first over-temperature trip unit and a second over-temperature trip unit; there are two AC / DC heating modules, namely a first AC / DC heating module and a second AC / DC heating module; the high-voltage pulse bypass module includes a switching device with three electrodes, and the overload protector includes a first external electrode, a second external electrode, and a third external electrode; The first over-temperature trip unit and the first AC / DC heating module are connected in series between the first external electrode and the second external electrode, forming a first series node and a first current channel; the second over-temperature trip unit and the second AC / DC heating module are connected in series between the first external electrode and the third external electrode, forming a second series node and a second current channel, and the second external electrode and the third external electrode form a third current channel, the first current channel, the second current channel and the third current channel form a Y-type surge protection circuit; the three electrodes of the switching device are respectively connected to the first series node, the first external electrode and the second series node; The first external electrode is connected to a first terminal of the power supply via at least one first varistor; the second external electrode is connected to a second terminal of the power supply via at least one second varistor; and the third external electrode is connected to a third terminal of the power supply via at least one third varistor. In some embodiments, the high-voltage pulse bypass module includes a switching device, which is a gas discharge tube, a solid discharge tube, or a discharge gap. The lightning current level of the switching device is higher than the lightning current level of the protected varistor, and the DC operating voltage of the switching device is higher than the DC voltage withstand voltage of the overload protector.

[0013] A second aspect of this application provides a power device including a power input interface, at least one varistor, and an overload protector as described above, wherein the overload protector and the varistor are connected between at least two terminals of the power input interface.

[0014] The beneficial effects of this application embodiment compared with the prior art are as follows: When the voltage fluctuation of the power supply (such as the power grid or power generation equipment) causes the voltage to exceed the DC operating voltage of the protected varistor (i.e., the protected varistor), or when the DC operating voltage of the protected varistor drops due to deterioration and falls below the peak voltage of the power supply, the power supply will generate DC or AC current in the protected varistor. This AC or DC current flows simultaneously through the over-temperature trip unit and the AC / DC heating module connected in series with the protected varistor, causing the AC / DC heating module to generate a temperature rise. When the temperature of the AC / DC heating module reaches the operating temperature of the over-temperature trip unit, the over-temperature trip unit will activate and disconnect, disconnecting the entire overload protector from the power supply, thereby disconnecting the protected varistor from the power supply as well, preventing the protected varistor from being damaged by high temperature or even burning due to continuous AC / DC current overload. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a lightning protection circuit provided by existing technology; Figure 2 This is a schematic diagram of an overload protector for lightning protection circuit provided in one embodiment of this application; Figure 3 This is a schematic diagram of an overload protector for lightning protection circuit provided in one embodiment of this application; Figure 4 This is a schematic diagram of an overload protector for lightning protection circuit provided in one embodiment of this application; Figure 5 This is a circuit diagram of an overload protector used in a lightning protection circuit according to an embodiment of this application; Figure 6 This is a schematic diagram of the structure of an overload protector provided in one embodiment of this application; Figure 7 This is a schematic diagram of the core module of an overload protector provided in one embodiment of this application; Figure 8 This is a schematic diagram of the structure of an overload protector provided in one embodiment of this application; Figure 9 This is a schematic diagram of the structure of an overload protector provided in one embodiment of this application; Figure 10 This is a circuit diagram of an overload protector used in a lightning protection circuit according to an embodiment of this application; Figure 11 This is a circuit diagram of an overload protector used in a lightning protection circuit according to an embodiment of this application; Figure 12 This is a schematic diagram of the core module of an overload protector provided in one embodiment of this application; Figure 13 This is a schematic diagram of the structure of an overload protector provided in one embodiment of this application; Figure 14 This is a circuit diagram of an overload protector used in a lightning protection circuit according to an embodiment of this application. Detailed Implementation

[0017] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0018] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0019] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0020] 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.

[0021] In traditional SPD discharge circuits, the varistor connected to the AC power supply exhibits several common overload failure scenarios: 1. When the amplitude of the transient overvoltage (TOV) is higher than the operating voltage threshold (Uv) of the varistor, a power frequency current will flow through the varistor. When the heat power generated on the varistor exceeds the heat dissipation power of the varistor itself, the temperature of the varistor will continue to rise. If the TOV overvoltage lasts long enough, the varistor will thermally collapse and burn through, exhibiting a short-circuit burn-through state.

[0022] 2. During field service, if the energy of a lightning pulse or the cumulative number of impacts acting on the varistor exceeds the design limit of its valve plate, the operating voltage of the varistor will drop significantly, eventually resulting in a low resistance value and deterioration failure.

[0023] 3. For varistors that have been in field service for a long time, under the continuous stress of the mains voltage, the operating voltage of the varistor will gradually decrease at the end of its service life. When its threshold is lower than the peak voltage of the rated mains voltage, power frequency current will flow through the varistor. The continuous power frequency current will eventually cause the varistor to fail due to overheating and short circuit.

[0024] Varistors that enter a low-resistance state mostly exhibit a "tunnel-type burn-through" condition, meaning that a pinhole-like low-resistance channel connects the two electrodes of the varistor. When the power grid generates current through the failed varistor, the current will only flow through this low-resistance channel and will not flow through other high-resistance regions. The blackened and carbonized zinc oxide tunnel does not exhibit a completely short-circuit state with zero resistance, but rather a low-resistance state ranging from a few tenths of an ohm to several hundred ohms. If a varistor that has undergone tunnel burn-through cannot be quickly disconnected from the power grid, the following serious safety risks will arise: 1. Applying the rated mains voltage to a low-resistance channel with only a few tenths of an ohm to several hundred ohms may generate an AC current of tens to hundreds of amperes, which may cause the current channel to arc or cause the varistor to explode.

[0025] 2. A failed, short-circuited varistor can no longer withstand the impact of lightning current. A lightning current of several thousand amperes concentrated in a small, low-resistance tunnel will cause the channel to heat up rapidly. Thermal stress may cause the varistor to shatter instantly, and the splashed conductive fragments of the varistor may threaten the safety of electrical equipment.

[0026] To reduce the safety risk of high-temperature fire caused by short-circuit failure of varistors, manufacturers equip varistors with overload tripping devices. Common overload tripping devices for varistors include the following: 1. Connect a current fuse or a miniature circuit breaker (MCB) in series with the varistor. When the varistor fails and short-circuits, generating a large fault current, the fuse will blow or the circuit breaker will open to prevent the current from continuously heating the varistor.

[0027] 2. A varistor is connected in series with an external backup protector (Special Circuit Breaker, SCB). The fault current flows through the electromagnetic coil of the SCB, and the electromagnetic force drives the contact switch to separate, thereby cutting off the fault current of the varistor greater than 3A.

[0028] 3. Mount a thermal fuse or solder an alloy fuse on the surface of the varistor and connect it in series. If the varistor overheats, the low-temperature fuse will melt, cutting off the connection between the varistor and the AC power grid. 4. An elastic metal electrode is placed on the surface of the varistor, and the elastic electrode is soldered to the varistor with low-temperature solder. When the varistor heats up and exceeds the temperature, the low-temperature solder joint melts, causing the elastic electrode to detach from the varistor and cut off the fault current. 5. Based on the fourth design above, a mechanical mechanism with a pull-out spring and an arc-extinguishing slider is added to improve the reliability of the tripping mechanism and add a failure remote alarm function.

[0029] All five AC overload tripping designs mentioned above have certain safety hazards, and their respective defects are as follows: The first design, to ensure it doesn't trip during lightning strikes, typically requires AC operating currents greater than 10A for the current fuse and circuit breaker, thus failing to cut off fault currents below 10A. The second design, limited by the minimum drive current of the electromagnetic coil, also cannot trip for fault currents below 3A. Designs 3, 4, and 5 rely on fusing cryogenic alloys to achieve tripping. Their safety depends on the delay time of the over-temperature tripping mechanism. Under high TOV power frequency current surges (e.g., above 10A), the varistor often burns through quickly, entering a short-circuit state. Due to the delay in heat conduction, the over-temperature tripping mechanism may not have enough time to separate, causing the short-circuit current in the power grid to instantly increase to tens or even hundreds of amps. This extremely high short-circuit fault current exposes the varistor to safety risks such as high-temperature flames, explosions, and the ignition of the encapsulating plastic.

[0030] The technicians applying this application discovered that excessive power frequency current causes the varistor to heat up too quickly, to the point that the overload tripping device cannot trip in time before the varistor burns through and short-circuits. This results in the varistor being subjected to extremely high grid short-circuit current surges, causing dangerously high temperatures and heat generation. This is the main safety risk of traditional thermal protection varistors. To eliminate this risk, the problem of excessive power frequency current surges in varistors must be addressed. The magnitude of the power frequency current depends on the total impedance of the current loop, including: the internal resistance of the power grid, the equivalent resistance of the varistor, and the grounding resistance (if the varistor is connected to protective ground). The internal resistance of the power grid and the grounding resistance are determined by the power supply system and cannot be changed. The only way to change the equivalent total impedance is through the varistor itself.

[0031] On the other hand, when traditional TMOVs are applied to photovoltaic high-voltage DC ports, due to the high voltage and difficulty in interrupting DC arcing, a Y-type circuit consisting of three thermally tripped varistors is typically used for lightning protection. A typical circuit structure is as follows: Figure 1As shown in the figure, there are 12 TMOVs (TMOV1-12). The Y-type circuit is characterized by each current channel consisting of two TMOVs connected in series. When one TMOV fails due to a lightning strike and short-circuit, the photovoltaic voltage is applied to the terminals of the unfailed TMOV, causing it to experience a voltage overload of 1.1 to 1.3 times. Correspondingly, a DC current of 0.1 to 1A is generated across the varistor. This relatively small current allows the varistor to heat up at a relatively low rate, giving the heat sufficient time to conduct to the movable solder joint of the trip unit and melt the low-temperature solder. This allows the trip unit to disengage before the varistor overheats and short-circuits, thus preventing a dangerous short-circuit current in the varistor and safely disconnecting the failed varistor from the high-voltage DC grid, ensuring the safety of the TMOV varistor in case of failure. However, for... Figure 1 The inverter shown has multiple photovoltaic strings as inputs, requiring multiple TMOVs. Because TMOVs with arc-extinguishing mechanisms and remote signaling switches are structurally complex and expensive to manufacture, this lightning protection solution would impose significant cost pressures.

[0032] Figures 2 to 4 A schematic diagram of the overload protector provided in an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below: An overload protector 100 is provided, which is used to connect at least two terminals 11 and 12 of a power supply to a protected varistor MOV1, wherein, firstly, there is no thermal coupling between the overload protector 100 and the protected varistor MOV1; the overload protector 100 includes an AC / DC heating module 20, an over-temperature trip unit 30, and a high-voltage pulse bypass module 40, wherein the high-voltage pulse bypass module 40 is connected in parallel across the two ends of the AC / DC heating module 20, the over-temperature trip unit 30 is connected in series with the AC / DC heating module 20, and there is thermal coupling between the over-temperature trip unit 30 and the AC / DC heating module 20 (e.g., Figure 2-4 (As shown by the dashed line in the figure); the AC / DC heating module 20 has electrothermal characteristics. When the temperature rises to the operating temperature of the over-temperature trip unit 30 under the action of AC / DC current, the over-temperature trip unit 30 is triggered to trip and disconnect, cutting off the electrical connection between the overload protector 100 and the power supply.

[0033] The two terminals 11 and 12 of the power supply include a first terminal 11 and a second terminal 12. For example, the first terminal 11 and the second terminal 12 are respectively the live wire and the neutral wire, or the positive terminal and the negative terminal. Figures 2 to 4 Three connection methods are shown for connecting the overload protector 100 and the protected varistor MOV1 to the power supply. Among them, Figure 2In the example, the protected varistor MOV1 is connected to the first terminal 11, the over-temperature trip unit 30 is connected to the protected varistor MOV1, and the AC / DC heating module 20 is connected in series between the over-temperature trip unit 30 and the second terminal 12. Figure 3 In the example, the protected varistor MOV1 is connected to the first terminal 11, the AC / DC heating module 20 is connected to the protected varistor MOV1, and the over-temperature trip unit 30 is connected in series between the over-temperature trip unit 30 and the second terminal 12. Figure 4 In the example, the protected varistor MOV1 is connected to the second terminal 12, the AC / DC heating module 20 is connected to the protected varistor MOV1, and the over-temperature trip unit 30 is connected in series between the over-temperature trip unit 30 and the first terminal 11.

[0034] The working principle of the thermally separated overload protector 100 lightning protection scheme in this application embodiment is as follows: the overload protector 100, which is electrically connected in series with the protected varistor MOV1 but structurally independent of the protected varistor MOV1, provides the tripping action. The overload protector 100 and the protected varistor MOV1 are only electrically connected and not thermally coupled; therefore, it can be called a thermally separated overload protector 100, to distinguish it from the traditional thermally coupled TMOV type where the trip unit is tightly attached to the surface of the varistor.

[0035] The high-voltage pulse bypass module 40 provides a low-resistance discharge channel for the high-voltage pulse from lightning strikes, which can reduce the residual voltage after a lightning strike and reduce the interference of the AC / DC heating module 20 on the lightning protection effect. The DC operating voltage of the high-voltage pulse bypass module 40 should be higher than the maximum voltage of the power grid it operates on to prevent the high-voltage pulse bypass module 40 from being falsely triggered by the power grid.

[0036] When voltage fluctuations in the power supply (such as the power grid or power generation equipment) cause the voltage to exceed the DC operating voltage of the protected varistor MOV1, or when the DC operating voltage of the protected varistor MOV1 drops below the peak voltage of the power supply due to deterioration, the power supply will generate DC or AC current in the protected varistor MOV1. This current simultaneously flows through the over-temperature trip unit 30 connected in series with the protected varistor MOV1 and the AC / DC heating module 20, causing the AC / DC heating module 20 to heat up. When the temperature of the AC / DC heating module 20 reaches the operating temperature of the over-temperature trip unit 30, the over-temperature trip unit 30 will trip and disconnect the entire overload protector 100 from the power supply, thereby disconnecting the protected varistor MOV1 from the power supply as well, preventing the protected varistor MOV1 from being damaged by high temperature or even burning due to continuous AC / DC current overload.

[0037] Please see Figure 5In one embodiment, the high-voltage pulse bypass module 40 includes a switching device T1, which is a gas discharge tube, a solid discharge tube, or a discharge gap (e.g., a graphite discharge gap or a spark gap). The lightning current level of the switching device T1 is higher than the lightning current level of the protected varistor MOV1, and the DC operating voltage of the switching device T1 is higher than the DC voltage withstand voltage of the overload protector 100.

[0038] Please see Figure 5 In one embodiment, the AC / DC heating module 20 includes a current limiting element R2 and a heating element R1, with the current limiting element R2 and the heating element R1 connected in series.

[0039] The overload protector 100 does not need to be in contact or thermally coupled with the protected varistor MOV1. Instead, an independent heating element R1 is added inside the overload protector 100. This heating element R1 is electrically connected in series with the externally protected varistor MOV1.

[0040] The current limiting element R2 is used to significantly reduce the inrush current when the fault voltage is high, so as to prevent the excessive inrush current from damaging the heating element R1 and the externally connected series protected varistor MOV1.

[0041] In one embodiment, the current limiting element R2 and the heating element R1 are welded back to back. When current flows through the current limiting element R2, the heat generated can be conducted to the heating element R1 to increase the rate of temperature rise.

[0042] In one embodiment, the current-limiting element R2 and the heating element R1 are spaced apart and separately disposed (see [reference]). Figure 9 This can prevent the heating element R1 from conducting heat to the current-limiting element R2, thus affecting its performance and improving the stability of the circuit.

[0043] In one embodiment, the heating element R1 includes a varistor valve or a thermistor valve.

[0044] In one embodiment, the current-limiting element R2 includes a positive temperature coefficient thermistor with a Curie temperature higher than the operating temperature of the over-temperature trip unit 30. In another embodiment, the current-limiting element R2 includes a fixed resistor. Exemplarily, the resistance of the current-limiting element R2 is several hundred ohms or higher.

[0045] Since positive temperature coefficient thermistors have both current limiting and over-temperature self-protection functions, they are safer than resistors and have a smaller size. Considering the high requirements for thermal sensitivity, the AC / DC heating module 20 can use a varistor valve plate connected in series with a positive temperature coefficient thermistor.

[0046] In one embodiment, the heating element R1 includes a varistor valve, the temperature rise rate of which is higher than that of the protected varistor MOV1. For example, the equivalent heat capacity of the heating element R1 should be much smaller than that of the protected varistor MOV1, so the heat power generated per unit volume per unit time is greater than that of the protected varistor MOV1. Under the same current, the temperature rise rate of the heating element R1 is always higher than that of the protected varistor MOV1. Thus, the heating element R1 can reach its operating temperature before the protected varistor MOV1 does.

[0047] For example, if the ratio of the temperature rise rate of the varistor valve of the heating element R1 to that of the protected varistor MOV1 is set to K, then K = K1 / K2 = (Uv1*V2) / (Uv2*V1), where K1 represents the temperature rise rate of the varistor valve of the heating element R1, K2 represents the temperature rise rate of the protected varistor MOV1, Uv1 is the DC operating voltage of the varistor valve of the heating element R1, Uv2 is the DC operating voltage of the protected varistor MOV1, V1 is the equivalent heat capacity volume of the varistor valve of the heating element R1, and V2 is the equivalent heat capacity volume of the protected varistor MOV1. The operating voltage Uv is directly proportional to the temperature rise rate, while the equivalent heat capacity volume V is inversely proportional to the temperature rise rate (calculating the equivalent heat capacity volume requires comprehensive consideration of the heat storage factors of the metal electrodes welded on the valve and the encapsulation material). As long as the ratio K of the temperature rise rate is greater than 1, the temperature rise rate of the varistor valve of the heating element R1 can always be higher than the temperature rise rate of the protected varistor MOV1.

[0048] Please see Figure 5 In one embodiment, the overload protector 100 forms two external electrodes, namely a first electrode 101 and a second electrode 102, for connecting to the protected varistor MOV1 or the terminals of the power supply.

[0049] Please see Figure 5 and Figure 6 In one embodiment, the over-temperature trip unit 30 includes a movable metal elastic electrode 301. The end of the metal elastic electrode 301 is soldered to the surface electrode 201 of the heating element R1 by a low-temperature solder 302. The tip of the metal elastic electrode 301 is used to connect to the terminals of the protected varistor MOV1 or the power supply. The melting point temperature of the low-temperature solder 302 corresponds to the operating temperature of the over-temperature trip unit 30. It can be understood that the tip of the metal elastic electrode 301 is one of the external electrodes of the overload protector 100.

[0050] For example, by soldering the metal elastic electrode 301 onto the surface electrode 201 of the heating element R1 with low-temperature solder 302 with a melting point of 140°C, it can be ensured that after the over-temperature trip unit 30 operates to disconnect and cut off the current loop of the entire circuit, the temperature of the varistor MOV1 connected in series with it will not exceed 140°C, thereby achieving the purpose of thermal protection of the varistor MOV1 by the independent overload protector 100.

[0051] Please see Figure 5 , Figures 7-9 In one embodiment, the AC / DC heating module 20 and the high-voltage pulse bypass module 40 form a core module 105, and the over-temperature trip unit 30 further includes: The housing 310 has a welding window 307, a connection position 311 and a separation position 312, and the core module 105 and the metal elastic electrode 301 are mounted on the housing 310. The remote signaling switch 320 includes two remote signaling switch contacts 321 and 322 mounted on the housing 310; The arc-extinguishing slider 330 and the pull-out spring 340 are movably mounted on the sliding guide rail 314 of the housing 310; the metal elastic electrode 301 includes a holding section 301C connected between the end 301B and the beginning 301A. The beginning 301A of the metal elastic electrode 301 extends to the outside of the housing 310, and the holding section 301C is located outside the arc-extinguishing slider 330. The end 301B of the metal elastic electrode 301 is welded to the surface electrode 201 of the heating element R1 through the welding window 307 with low-temperature solder 302, so that the holding section 301C holds the arc-extinguishing slider 330 in the connection position 311 and presses the arc-extinguishing slider 330 against the remote signaling switch 320 to bring the two remote signaling switch contacts 321 and 322 into contact; and The pull-out spring 340 is used to generate an elastic restoring force to drive the arc-extinguishing slider 330 to move toward the separation position 312, pulling the arc-extinguishing slider 330 to reach and cover the welding window 307 so as to be positioned between the end 301B of the metal elastic electrode 301 and the surface electrode 201 of the heating element R1, thereby blocking the electrical connection between the end 301B of the metal elastic electrode 301 and the surface electrode 201 of the heating element R1. This also separates the two remote signaling switch contacts 321 and 322.

[0052] For example, the housing 310 and the arc-extinguishing slider 330 are made of plastic. By soldering the end 301B of the metal elastic electrode 301 to the surface electrode 201 of the heating element R1 with low-temperature solder 302 with a melting point of 140°C, it can be ensured that after the over-temperature trip unit 30 operates and disconnects the current loop of the entire circuit, the temperature of the varistor MOV1 connected in series with it will not exceed 140°C, thereby achieving the purpose of thermal protection of the varistor MOV1 by the independent overload protector 100.

[0053] For example, both the varistor valve, which serves as the heating element, and the thermistor, which serves as the current limiting element, in the AC / DC heating module 20 can generate heat and high temperatures. The metal elastic electrode 301 of the over-temperature trip unit 30 can be welded to either the surface electrode 201 of the varistor or the surface electrode of the thermistor. Considering that the temperature rise rate of the varistor valve under a small current in the milliampere range is much higher than that of the thermistor, i.e., the thermal sensitivity of the varistor valve is higher under a small current, the metal elastic electrode 301 is generally welded to the surface electrode 201 of the varistor valve.

[0054] In one embodiment, the AC / DC heating module 20 and the parallel high-voltage pulse bypass module 40 are installed together in the housing 310, and then equipped with an over-temperature trip unit 30, an auxiliary arc-extinguishing slider 330, and a remote signaling switch 320, thus forming a configuration as shown in the figure. Figure 7 The complete single-channel (referring to the two electrodes used to connect the power supply) overload protector 100 is shown.

[0055] An example of the assembly process for the above-mentioned single-channel overload protector 100 is as follows: 1) The current-limiting element R2 is stacked and connected in series with the heating element R1 via a flat electrode 303, and then connected in parallel with the switching device T1 via two flat electrodes 304 and 305 to form the core module 105 of the overload protector 110. It can be understood that the first end 301A of the metal elastic electrode 301 extends to the outside of the housing 310, that is, the flat electrode 305 and the first end 301A of the metal elastic electrode 301 are respectively connected to or serve as the first external electrode 101 and the second external electrode 102, and the flat electrode 304 includes the aforementioned surface electrode 201.

[0056] 2) The core module 115 is installed into the pit 306 of the plastic shell 313 and fixed to the shell 313 with potting epoxy resin. Only the welding area of ​​the surface electrode 201 of the heating element R1 is exposed at the welding window 307 of the pit 306, which is used to weld the end 301B of the metal elastic electrode 301. 3) Insert the two switch contacts 321 and 322 of the remote signaling switch 320 into the slots of the plastic housing 313.

[0057] 4) Insert the arc-extinguishing slider 330 into the sliding guide rail 314 of the plastic inner shell 313 and slide it to the rightmost position, i.e. the connection position 311, so that the lower end of the arc-extinguishing slider 33 presses tightly against the movable switch contact 321 of the remote signaling switch 320 and touches the fixed switch contact 322 of the remote signaling switch 320, so that the two remote signaling switch contacts 321 and 322 are connected. 5) Insert the first external terminal 101 of the overload protector 100 into the positioning hole of the plastic inner shell 313, press the metal elastic electrode 301 into the pre-opened welding window 307 of the plastic inner shell 313 and press it against the surface electrode 201 of the core module 105, and then use a soldering iron to reliably solder the two together with low temperature alloy solder. 6) The first external terminal 101 is soldered to the flat electrode 305 of the core module 115 using high-temperature solder; 7) Press the end hooks of the two pull-out springs 340 into the locking post of the arc-extinguishing slider 330 and the locking post 315 of the plastic inner shell 313 respectively, so that the arc-extinguishing slider 330 is tightened by the pull-out springs 340. 8) Insert the plastic outer shell (not shown) into the plastic inner shell 310 to complete the assembly process of the overload protector 100.

[0058] The working process of the single-channel overload protector 100 is as follows: The overload protector 100 is used in series with the protected varistor MOV1. Under normal circumstances, the operating voltage of the protected varistor MOV1 is higher than the peak voltage of the power grid, and no current flows through the protected varistor MOV1 and the overload protector 100, so the overload protector 100 does not generate heat.

[0059] After the protected varistor MOV1 is damaged, its operating voltage will gradually decrease. When its operating voltage is significantly lower than the peak voltage of the power grid, a continuous current will flow through the protected varistor MOV1 and the overload protector 100. Both the protected varistor MOV1 and the varistor (i.e., the heating element R1) inside the overload protector 100 will generate heat. However, the volume of the varistor inside the overload protector 100 is much smaller than that of the protected varistor MOV1. Therefore, the temperature rise rate of the varistor inside the overload protector 100 is higher than that of the protected varistor MOV1. After the varistor inside the overload protector 100 reaches 140°C, the low-temperature solder 302 of the over-temperature trip unit 30 softens, causing the end 301B of the metal elastic electrode 301 of the over-temperature trip unit 30 to quickly detach from the soldering window 307 under the tension of the spring. The arc-extinguishing slider 330 is pulled by the spring from... Figure 8When the rightmost slider (connection position 311) slides to the leftmost slider (separation position 312), it covers the welding window 307, preventing electrical connection between the end 301B of the metal elastic electrode 301 of the thermal trip unit 30 and the surface electrode 201 of the core module 1153. This cuts off the current circuit of the protected varistor MOV1, preventing it from continuously overheating. At the same time, after the arc-extinguishing slider 330 moves to the separation position 312, the movable switch contact 321 of the remote signaling switch 320, which was originally pressed by the arc-extinguishing slider 330, is released. The movable switch contact 321 springs upward under its own elastic force and separates from the fixed switch contact 322, changing from a normal closed connected state to an open open state, thus completing the telemetry signal alarm function.

[0060] Example 1: for Figures 7 to 9 As shown, the single-channel overload protector 100, if to be applied to U CPV It is a 1200Vdc photovoltaic DC port, and adopts Figure 5 or Figure 10 For the lightning protection circuit shown, the selection of each component in the overload protector 100 can be arranged as follows: Switching device T1: A two-pole SMD surface-mount gas discharge tube with a diameter of 8mm, a length of 6mm, a DC operating voltage of 1000Vdc, and a rated discharge current of 20KA is selected.

[0061] Heating element R1: A surface-mount varistor with a diameter of 10mm, a thickness of 1mm, and a varistor voltage of 90Vdc, printed with silver.

[0062] Current limiting element R2: Select a surface-mount thermistor with printed silver, which has a diameter of 8mm, a thickness of 2.5mm, a room temperature resistance of 1KΩ, and a Curie temperature of 160°C.

[0063] Low-temperature solder 302: Sn42Bi58 low-temperature alloy solder with a melting point of 138°C is recommended for soldering the movable terminals of the trip unit.

[0064] A sample of the overload trip unit 100, made using the above components, was subjected to an overload failure simulation test with a protected varistor MOV1 (e.g., a 25D821K varistor with a valve diameter of 25mm, a valve thickness of 4mm, a varistor voltage of 820Vdc, and a lightning strike current of 10KA, encapsulated in epoxy resin). The test wiring was performed according to the IEC-61643-31_2019 standard; that is, the protected varistor MOV1 was connected in series with the overload protector 100, and a 1200Vdc DC regulated power supply was applied to both until tripping. The test results showed that after voltage application, the overload protector 100 tripped within 5 seconds, with a maximum DC current of 150mA. The highest surface temperature of the protected varistor MOV1 was 115°C. Both the tripping time and the highest varistor temperature met the acceptance criteria of the IEC-61643-31_2019 standard. Figure 10 The protected varistors MOV1 and MOV2 were connected in series with the overload protector 100. An 8 / 20µs lightning strike generator was used to perform an action load lightning strike test (connection and 1200Vdc power supply were applied according to the IEC-61643-11_2011 standard). After 15 10KA lightning strike tests (divided into 3 groups, 5 times per group, with 60s interval between each test), the overload protector 100 did not trip, the remote signaling switch 320 remained closed, and the varistors were undamaged, meeting the acceptance criteria of the IEC-61643-11_2011 standard.

[0065] refer to Figure 10 In one embodiment, for protecting the circuit with a three-terminal power input, an independent overload protector 100 is connected between the first terminal 11 and the second terminal 12, and between the first terminal 11 and the third terminal 13. A varistor MOV1, MOV2, and MOV3 to be protected are connected in series to the first terminal 11, the second terminal 12, and the third terminal 13 of the three-terminal power supply. Two overload protectors 100 can simultaneously protect all three varistor MOV1, MOV2, and MOV3. Varistors MOV1 and MOV2 are connected to the first external electrode 101 and the second external electrode 102 of the first overload protector 110, respectively, and varistor MOV1 and MOV3 are connected to the first external electrode 101 and the second external electrode 102 of the second overload protector 110, respectively.

[0066] In this embodiment, the two overload protectors 110 operate independently, protecting different varistors respectively. If one of them fails, it can be replaced individually, saving costs. Furthermore, compared to conventional three-terminal power input overvoltage protection methods, which require three SPDs or TMOVs with over-temperature tripping mechanisms, this embodiment saves at least one over-temperature tripping mechanism, reducing costs and the required space.

[0067] refer to Figures 11 to 13 In another embodiment, when used to protect the circuit of a three-terminal power input, the overload protector 100 includes a first external electrode 101, a second external electrode 102, and a third external electrode 103. These are respectively used to connect the live wire, neutral wire, and ground wire, or the positive terminal, negative terminal, and ground wire of the three-terminal power supply.

[0068] The overload protector 100 has two over-temperature trip units, namely the first over-temperature trip unit 31 and the second over-temperature trip unit 32; there are two AC / DC heating modules, namely the first AC / DC heating module 21 and the second AC / DC heating module 22; the high-voltage pulse bypass module 40 includes a switching device T2 with three electrodes; the first over-temperature trip unit 31 and the first AC / DC heating module 21 are connected in series between the first external electrode 101 and the second external electrode 102, forming a first series node; the second over-temperature trip unit 32 and the second AC / DC heating module 22 are connected in series between the first external electrode 101 and the third external electrode 103 and the first current channel, forming a second series node and a second current channel; and the second external electrode 102 and the third external electrode 103 form a third current channel, and the first current channel, the second current channel and the third current channel form a Y-type surge protection circuit. The three electrodes of the switching device T2 are connected to the first series node, the first external electrode 101, and the second series node, respectively. The first external electrode 101 is connected to the first terminal 11 of the power supply through at least one first varistor MOV1. The second external electrode 102 is connected to the second terminal 12 of the power supply through at least one second varistor MOV2. The third external electrode 103 is connected to the third terminal 12 of the power supply through at least one third varistor MOV3. The first varistor MOV1, the second varistor MOV2, and the third varistor MOV3 are the varistors being protected. The Y-type surge protection circuit is suitable for typical photovoltaic DC ports.

[0069] In this embodiment, the overload protector 100 for the three-terminal power input is made into a single unit, saving costs.

[0070] The assembly process of the above three-channel overload protector 100 is as follows: 1) Assemble the switching device T2, two thermistors R2, two varistors R1, and four flat electrodes according to... Figure 12 The circuit schematic shown is overlaid and soldered together to form the core module 106 of the protector. In practice, it can be considered as combining two... Figure 7The flat electrodes 305 of the core module 105 shown are soldered back-to-back on one side. Two flat electrodes 305 are replaced with one, and the flat electrode 305 is soldered to the middle electrode and the first external electrode 101 of the switching device T2. The two end electrodes of the switching device T2 are respectively soldered to the surface electrodes 201 of the two heating elements R1. The surface electrodes 201 of the two heating elements R1 are respectively connected to the second external electrode 103 of the first over-temperature trip unit 31 and the third external electrode 103 of the second over-temperature trip unit 32.

[0071] 2) Install the core module 106 into the slot 306 of the plastic inner shell 313 (see...) Figure 9 Inside, the first end 301A of the metal elastic electrode 301 of the first over-temperature trip unit 31 is connected to the second external electrode 102, and the first end 301A of the metal elastic electrode 301 of the second over-temperature trip unit 32 is connected to the third external electrode 103. The core module 106 and the middle shell 313 are fixed together with potting epoxy resin. Only the welding area of ​​the surface electrode 201 of the heating element R1 is exposed at the window 307, which is used to weld the end 301B of the metal elastic electrode 301. 3) Install the four switch contacts of the two sets of remote signaling switches 320 into the slots of the plastic housing 313 respectively; 4) Insert the two arc-extinguishing sliders 330 into the sliding guide rails 314 of the plastic inner shell 313 and slide them to the connection position 311, so that the lower end of the arc-extinguishing slider 330 presses tightly against the movable switch contact 321 of the remote signaling switch 320 and touches the fixed switch contact 322 of the remote signaling switch 320, forming a connected state. 5) Insert the first external terminal 101 into the positioning hole of the plastic inner shell 313, press the two metal elastic electrodes 301 into the pre-opened welding window 307 of the plastic inner shell 313 and press them against the two surface electrodes 201 of the core module 106, and then weld them together with low temperature alloy solder at 140°C. 6) Press the end hooks of the four pull-out springs 340 into the locking posts of the arc-extinguishing slider 330 and the locking posts 315 of the plastic inner shell 313 respectively, so that the arc-extinguishing slider 330 is tightened by the pull-out springs 340. 7) Insert the plastic outer shell (not shown) into the plastic inner shell 313 to complete the assembly process of the three-channel overload protector 100.

[0072] A three-channel overload protector 100 can be configured as follows: Figure 5 The lightning protection circuit shown below operates as follows: Protected varistors MOV1, MOV2, and MOV3 are connected in series on the first terminal 11, second terminal 12, and third terminal 13 of the three-terminal power supply, respectively. The first external electrode 101, second external electrode 102, and third external electrode 103 of the three-channel overload protector 100 are connected in series with the protected varistors MOV1, MOV2, and MOV3, respectively. Under normal circumstances, the operating voltage of the protected varistors MOV1, MOV2, and MOV3 is higher than the peak voltage of the power grid. No current flows through the protected varistors MOV1, MOV2, and MOV3 and the overload protector 100, so the overload protector 100 does not generate heat.

[0073] If any one of the protected varistors MOV1, MOV2, and MOV3 (e.g., MOV1) is damaged and becomes low-resistance or short-circuited, the power supply voltage (e.g., photovoltaic cell voltage) will be higher than the operating voltage of the current loop formed by the remaining varistors (MOV2 and MOV3) in the circuit, thereby generating a continuous DC current. The protected varistors MOV2 and MOV3 and the heating element R1 inside the overload protector 100 will all generate heat, but the volume of the heating element R1 is much smaller than that of the protected varistors MOV2 and MOV3. Therefore, the heating element R1 has a higher temperature rise rate than the protected varistor MOV2 and MOV3. After the heating element R1 reaches 140°C, the low-temperature solder 302 at the end 301B of the metal elastic electrode 301 softens, causing the metal elastic electrode 301 to quickly detach from the welding window 307 under the pulling force of the spring 340. The arc extinguishing slider 330 slides from the connection position 311 to the separation position 312 under the pulling force of the spring 340. The slider covers the welding window 307, preventing electrical connection between the metal elastic electrode 301 and the surface electrode 201 of the core module 106, cutting off the current circuit of the protected varistor MOV1, MOV2, and MOV3, and preventing them from continuously heating up. At the same time, after the arc-extinguishing slider 330 slides to the separation position 312, the movable switch contact 321 of the remote signaling switch 320, which was originally pressed by the arc-extinguishing slider 330, is released. The movable switch contact 321 bounces upward under its own elastic force and separates from the fixed switch contact 322, changing from the normal closed connected state to the open open state, thus completing the remote signal alarm function.

[0074] Example 2, for Figures 12 to 13 The three-channel overload protector 100 shown is intended for use in U... CPV It is a 1200Vdc photovoltaic DC port, and adopts Figure 11 For the lightning protection circuit shown, the selection of each component in the overload protector 100 can be arranged as follows: Switching device T2: A triode SMD surface mount gas discharge tube with a diameter of 8mm, a length of 10mm, a DC operating voltage of 1000Vdc, and a rated discharge current of 20KA.

[0075] Heating element R1: A surface-mount varistor with a diameter of 10mm, a thickness of 1mm, and a varistor voltage of 90Vdc is selected.

[0076] Current limiting element R2: It is advisable to select a surface-mount thermistor with printed silver, which has a diameter of 8mm, a thickness of 2.5mm, a room temperature resistance of 1KΩ, and a Curie temperature of 160°C.

[0077] Low-temperature solder 302: A low-temperature alloy solder with a melting point of 138°C using Sn42Bi58, used for soldering the movable terminals of the trip unit.

[0078] The overload trip unit 100 sample, made using the above components, is combined with three protected varistors MOV1, MOV2, and MOV3 (e.g., 25D821K varistors, epoxy-encapsulated varistors with a valve diameter of 25mm, a valve thickness of 4mm, a varistor voltage of 820Vdc, and a lightning strike current of 10KA) to form a circuit as follows: Figure 11 The surge protection circuit shown was subjected to an overload failure simulation test. The test wiring was performed according to the IEC-61643-31_2019 standard, specifically by shorting one of the protected varistors, MOV1 or MOV2, with a copper wire. Then, a 1200Vdc DC regulated power supply was applied between the first electrode 11 and the third electrode 13 until tripping. The test results showed that after voltage application, the maximum DC current was 150mA, the overload protector 100 tripped within 5 seconds, and the highest surface temperature of the protected varistor was 115°C. Both the tripping time and the highest temperature of the protected varistor met the acceptance criteria of the IEC-61643-31_2019 standard. If... Figure 11 The protected varistor was connected in series with the overload protector 100. An 8 / 20µs lightning strike generator was used to perform an action load lightning strike test (connection and 1200Vdc power supply were applied according to the IEC-61643-11_2011 standard). After 15 10KA lightning strike tests (divided into 3 groups, 5 times per group, with 60s interval between each test), the overload protector 100 did not trip, the remote signaling switch 320 remained closed, and the protected varistor was undamaged. The test results met the acceptance criteria of the IEC-61643-11_2011 standard.

[0079] Please see Figure 14 , Two similar Figure 10 The single-channel overload protector 100 is integrated into a plastic housing, which can form a combination such as Figure 11 The three-channel overload protector 100 shown here, with its T-shaped structure, is more suitable for use in [facilities / systems]. Figure 1 The Y-type circuit structure shown is applied in, for example... Figure 14 The high-voltage photovoltaic DC port shown can replace the traditional Figure 1 The surge protection circuit provides customers with significant cost reductions and enhanced safety performance for their equipment.

[0080] Since the thermally separated overload protector 100 does not need to exchange heat with the protected varistors MOV1, MOV2, and MOV3, it only needs to be connected to the protected varistors MOV1, MOV2, and MOV3 according to... Figure 14 The circuit shown can be electrically connected. At the same time, the over-temperature trip unit 30 is placed on the surface electrode 201 of the heating element R1. The heat of the heating element R1 melts the low-temperature solder 302 of the over-temperature trip unit 30, causing the over-temperature trip unit 30 to act and separate.

[0081] The core elements of the overload protector 100 are the heating element R1 and the metal elastic electrode 301 of the over-temperature trip unit 30 soldered to the surface of the heating element R1. Other surrounding components, such as the current limiting element R2 and the switching devices T1 and T2, are only auxiliary devices. For example, the current limiting element R2 is responsible for limiting the amplitude of the DC current, and the switching devices T1 and T2 provide a low-resistance pulse bypass channel for the heating element R1 to reduce the residual voltage after lightning strikes. These two types of auxiliary devices do not require heat transfer between themselves and the heating element R1, so they can be placed freely in any position, only needing to be electrically connected according to the circuit principle.

[0082] Among the components of the overload protector 100, such as the heating element R1, the current limiting element R2, the switching device T1, and the over-temperature trip unit 30, except that the over-temperature trip unit 30 and the heating element R1 must be in close contact for heat conduction, the other components can be placed freely. They can be soldered onto the circuit board as discrete components and electrically connected by the PCB copper foil, or they can be integrated by flat metal electrodes to form a compact integrated module.

[0083] The overload protector 100 has two current channels. One is a DC current channel that provides a path for the heating current. This channel is characterized by a low starting voltage (e.g., 100Vdc ~ 200Vdc), a high equivalent resistance (e.g., several hundred ohms or more), and a size that is only a fraction of the protected varistor MOV1, MOV2, and MOV3. It exhibits a significant heating effect and a much higher temperature rise rate than the protected varistor MOV1, MOV2, and MOV3. The other is a lightning pulse channel. This channel is characterized by a very high starting voltage, preventing DC heating current from flowing through it. It also exhibits negative resistance characteristics, resulting in a very low equivalent resistance after being triggered by a high-voltage pulse, thus reducing residual voltage after a lightning strike. These two channels operate independently, each performing its specific function without interference.

[0084] The main component of the over-temperature trip unit 30 is the metal elastic electrode 301. The first end 301A of the metal elastic electrode 301 is inserted into the support hole of the housing 310, and the last end 301B is soldered to the surface electrode 201 of the heating element R1 with low temperature alloy solder of 120~140°C. At the same time, the over-temperature trip unit 30 is accelerated to separate and reliably extinguish the arc by using an arc-extinguishing slider 330 and a pull-out spring.

[0085] The component that provides the telemetry signal in the over-temperature trip unit 30 is the remote signaling switch 320 with normally closed switch contacts. Under normal circumstances, the movable switch contact 321 of the remote signaling switch 320 is pressed down by the arc-extinguishing slider 330 and touches the fixed switch contact 322 of the switch. When the over-temperature trip unit 30 is disengaged, the arc-extinguishing slider 330 slides laterally, releasing the pressure on the movable switch contact 321 of the remote signaling switch 320. The movable switch contact 321 rebounds under its own elastic force, causing the two switch contacts to be separated. The telemetry signal changes to an open circuit state, notifying the external detector SPD that it has failed.

[0086] The heating element R1 is selected as a varistor valve. The following conditions should be met in the selection: After determining the specifications of the varistor voltage being protected, the power generated per unit volume of the varistor valve must be higher than the power generated per unit volume of the varistor voltage being protected. Specifically, it is necessary to ensure that the temperature rise rate of the varistor valve in the overload protector 100 is higher than the temperature rise rate of the varistor voltage being protected.

[0087] One embodiment of this application also provides an electrical device, including a power input interface, at least one varistor, and an overload protector 100 as described in any of the above embodiments, wherein the overload protector 100 and the varistor MOV1 are connected between at least two terminals of the power input interface.

[0088] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments 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 can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0089] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0090] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. An overload protector, characterized in that, The overload protector is used to connect to at least two terminals of the power supply with the protected varistor; there is no thermal coupling between the overload protector and the protected varistor; the overload protector includes an over-temperature trip unit, an AC / DC heating module, and a high-voltage pulse bypass module, the high-voltage pulse bypass module is connected in parallel across the two ends of the AC / DC heating module, the over-temperature trip unit is connected in series with the heating module, and there is thermal coupling between the over-temperature trip unit and the AC / DC heating module; the AC / DC heating module has electrothermal characteristics, and when it heats up to the operating temperature of the over-temperature trip unit under the action of AC / DC current, it triggers the over-temperature trip unit to trip and disconnect, cutting off the electrical connection between the overload protector and the power supply.

2. The overload protector as described in claim 1, characterized in that, The AC / DC heating module includes a current limiting element and a heating element, wherein the current limiting element and the heating element are connected in series.

3. The overload protector as described in claim 2, characterized in that, The current limiting element is welded back-to-back with the heating element, or the current limiting element and the heating element are spaced apart and separately arranged.

4. The overload protector as described in claim 2, characterized in that, The heating element includes a varistor valve or a thermistor valve; The current limiting element includes a positive temperature coefficient thermistor, the Curie temperature of which is higher than the operating temperature of the over-temperature trip unit; or the current limiting element includes a fixed resistor.

5. The overload protector as described in claim 2, characterized in that, The heating element includes a varistor valve, and the temperature rise rate of the varistor valve is higher than the temperature rise rate of the protected varistor.

6. The overload protector as described in claim 2, characterized in that, The over-temperature trip unit includes a movable metal elastic electrode at one end, the end of which is soldered to the surface electrode of the heating element by low-temperature solder, and the first end of which is used to connect to the protected varistor or the terminal of the power supply. The melting point of the low-temperature solder corresponds to the operating temperature of the over-temperature trip unit.

7. The overload protector as described in claim 6, characterized in that, The AC / DC heating module and the high-voltage pulse bypass module form a core module, and the over-temperature trip unit also includes: The housing has a welding window, a connection position, and a separation position, and the core module and the metal elastic electrode are mounted on the housing; The remote signaling switch includes two remote signaling switch contacts mounted on the housing; An arc-extinguishing slider and a pull-out spring are provided, the pull-out spring being movably mounted on a sliding guide rail of the housing; the metal elastic electrode includes a retaining section connected between an end and a beginning, the beginning of the metal elastic electrode extending to the outside of the housing, the retaining section being located outside the arc-extinguishing slider, and the end of the metal elastic electrode being soldered to the surface electrode of the heating element with low-temperature solder through the welding window, such that the retaining section holds the arc-extinguishing slider in the connection position and causes the arc-extinguishing slider to press against the remote signaling switch, thereby bringing the two remote signaling switch contacts into contact; The pull-out spring is used to generate an elastic restoring force to drive the arc-extinguishing slider to move toward the separation position, pull the arc-extinguishing slider to reach and cover the welding window, so as to be placed between the surface electrode of the heating element and the end of the metal elastic electrode, and to separate the two remote signaling switch contacts.

8. The overload protector as described in any one of claims 1 to 7, characterized in that, The over-temperature trip unit consists of two components, namely a first over-temperature trip unit and a second over-temperature trip unit; the AC / DC heating module consists of two components, namely a first AC / DC heating module and a second AC / DC heating module; the high-voltage pulse bypass module includes a switching device with three electrodes; and the overload protector includes a first external electrode, a second external electrode, and a third external electrode. The first over-temperature trip unit and the first AC / DC heating module are connected in series between the first external electrode and the second external electrode, forming a first series node and a first current channel; The second over-temperature trip unit and the second AC / DC heating module are connected in series between the first external electrode and the third external electrode, forming a second series node and a second current channel. The second external electrode and the third external electrode form a third current channel. The first current channel, the second current channel, and the third current channel form a Y-type surge protection circuit. The three electrodes of the switching device are respectively connected to the first series node, the first external electrode, and the second series node. The first external electrode is connected to a first terminal of the power supply via at least one first varistor; the second external electrode is connected to a second terminal of the power supply via at least one second varistor; and the third external electrode is connected to a third terminal of the power supply via at least one third varistor.

9. The overload protector as described in any one of claims 1 to 7, characterized in that, The high-voltage pulse bypass module includes a switching device, which is a gas discharge tube, a solid discharge tube, or a discharge gap. The lightning current level of the switching device is higher than the lightning current level of the protected varistor, and the DC operating voltage of the switching device is higher than the DC voltage withstand voltage of the overload protector.

10. An electrical device, characterized in that, It includes a power input interface, at least one varistor, and an overload protector as described in any one of claims 1-9, wherein the overload protector and the varistor are connected between at least two terminals of the power input interface.

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