A circuit low voltage early warning protector

Abstract

This utility model discloses a low-voltage early warning protector for circuits, belonging to the technical field of low-voltage protectors. It solves the problem that in actual operation, low-voltage protectors trip when the phase voltage rises due to lightning induction, operational overvoltage, or neutral line breakage, reaching the operating threshold. It includes a protector body and a transient overvoltage identification circuit. The protector body includes a trip unit, and the transient overvoltage identification circuit is electrically connected to the trip unit. During operation, the transient overvoltage identification circuit detects the input overvoltage state by comparing voltage sampling with a reference voltage. It uses RC delay to distinguish between transient and sustained overvoltage, and only drives the relay to close its contacts to trigger the trip unit when the overvoltage exceeds the threshold for more than x seconds.

Description

Technical Field

[0001] This utility model relates to the field of low-voltage protector technology, and in particular to a circuit low-voltage early warning protector. Background Technology

[0002] A low-voltage protector is a safety protection device used in low-voltage circuits, typically referring to AC 1000V and below. It monitors faults such as overcurrent, short circuit, overload, and leakage current in the circuit. When an abnormality occurs, it quickly cuts off the power supply to prevent equipment damage or accidents such as fires and electric shocks. With its compact structure and integrated multiple protection functions, it is installed in distribution boxes or inside electrical appliances and is widely used in low-voltage power applications such as homes, shopping malls, and factories. It is a key device for ensuring the safe and stable operation of low-voltage circuits.

[0003] In actual operation, the low-voltage circuit protector may trip when the phase voltage rises due to lightning induction, switching overvoltage, or neutral line breakage, causing the protector to reach its operating threshold.

[0004] Therefore, a low-voltage warning protector for circuits is proposed to solve or alleviate the above problems. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-voltage warning protector for circuits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A circuit low-voltage early warning protector includes a protector body and a transient overvoltage identification circuit. The protector body includes a trip unit. The transient overvoltage identification circuit is electrically connected to the trip unit. The transient overvoltage identification circuit detects the input overvoltage state by comparing the voltage divider sampling with a reference voltage and uses a resistor-capacitor delay network to distinguish between transient overvoltage and continuous overvoltage. The circuit triggers the trip unit after the overvoltage exceeds the threshold for more than x seconds.

[0008] Preferably, the instantaneous overvoltage identification circuit includes an input protection module, a voltage sampling module, a reference comparison module, a delay judgment module, and a trip execution module;

[0009] The AC power live wire input terminal of the input protection module is used for the live wire terminal of the external power supply. The AC power neutral wire input terminal of the input protection module is connected to the neutral wire terminal of the external power supply. The voltage signal acquisition terminal of the voltage sampling module is connected to the live wire output terminal of the input protection module. The voltage divider signal output terminal of the voltage sampling module is connected to the inverting input terminal of the reference comparison module. The reference voltage input terminal of the reference comparison module is connected to the reference output terminal of the independent reference voltage source. The overvoltage state output terminal of the reference comparison module is connected to the trigger signal input terminal of the delay judgment module. The delay action output terminal of the delay judgment module is connected to the drive control terminal of the trip execution module. The output terminal of the trip execution module is connected to the input terminal of the trip unit.

[0010] Preferably, the input protection module includes a transient suppression diode, the cathode of which is connected to the live wire terminal of the external power supply, and the anode of which is connected to the neutral wire terminal of the external power supply.

[0011] Preferably, the voltage sampling module includes a first voltage divider resistor and a second voltage divider resistor. One end of the first voltage divider resistor is connected to the cathode of the transient suppression diode in the input protection module, and the other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor and the inverting input terminal of the reference comparison module. The other end of the second voltage divider resistor is grounded.

[0012] Preferably, the reference comparison module includes a TL431 reference voltage source chip and an LM393 voltage comparator. The anode of the TL431 reference voltage source chip is grounded, and the cathode of the TL431 reference voltage source chip is connected to power through a first current-limiting resistor. The first inverting input terminal of the LM393 voltage comparator is connected to the voltage divider output terminal of the voltage sampling module, and the first output terminal of the LM393 voltage comparator is connected to the trigger signal input terminal of the delay judgment module.

[0013] Preferably, the delay judgment module includes a delay resistor, a delay capacitor, and a threshold voltage divider network. One end of the delay resistor is connected to the first output terminal of the LM393 voltage comparator, and the other end of the delay resistor is connected to the positive terminal of the delay capacitor and the second inverting input terminal of the LM393 voltage comparator. The negative terminal of the delay capacitor is grounded. The second output terminal of the LM393 voltage comparator is connected to the drive control terminal of the trip execution module. The threshold voltage divider network includes a pull-up resistor and a pull-down resistor. One end of the pull-up resistor is energized, and the other end of the pull-up resistor is connected to ground in series with the pull-down resistor. The second non-inverting input terminal of the LM393 voltage comparator is connected to the connection node between the pull-up resistor and the pull-down resistor.

[0014] Preferably, the tripping execution module includes a driving transistor, a single-pole double-throw relay, and a freewheeling protection diode. The base of the driving transistor is connected to the second output terminal of the LM393 voltage comparator in the reference comparison module through a second current-limiting resistor. The emitter of the driving transistor is grounded. The collector of the driving transistor is connected to the coil of the single-pole double-throw relay and then energized. The common terminal of the contacts of the single-pole double-throw relay is used to connect to an external tripping power supply. The normally open terminal of the contacts of the single-pole double-throw relay is connected to the trip unit. The anode of the freewheeling diode is connected to the collector of the driving transistor, and the cathode of the freewheeling diode is energized.

[0015] This utility model has the following beneficial effects:

[0016] During operation, this invention detects the input overvoltage state by comparing the voltage sampling of the instantaneous overvoltage identification circuit with the reference voltage, and uses RC delay to distinguish between instantaneous overvoltage and continuous overvoltage. Only when the overvoltage exceeds the threshold and lasts for more than x seconds will the relay close its contacts to trigger the trip unit to operate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 This is a block diagram of the instantaneous overvoltage identification circuit of this utility model.

[0020] 1. Protector body; 101. Trip unit; 2. Input protection module; 3. Voltage sampling module; 4. Reference comparison module; 5. Delay judgment module; 6. Trip execution module. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component 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 utility model.

[0025] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0026] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0027] A low-voltage warning protector for circuits, such as Figure 1 As shown, the device includes a protector body 1 and a transient overvoltage identification circuit. The protector body 1 includes a trip unit 101. The transient overvoltage identification circuit is electrically connected to the trip unit 101. The transient overvoltage identification circuit detects the input overvoltage state by comparing the voltage divider sampling with the reference voltage and uses an RC delay network to distinguish between transient overvoltage and continuous overvoltage. After the overvoltage exceeds the threshold for more than x seconds, the trip unit 101 is triggered.

[0028] like Figure 2As shown, the instantaneous overvoltage identification circuit includes an input protection module 2, a voltage sampling module 3, a reference comparison module 4, a delay judgment module 5, and a trip execution module 6. The AC power live wire input terminal of the input protection module 2 is used for the live wire terminal of the external power supply, and the AC power neutral wire input terminal of the input protection module 2 is connected to the neutral wire terminal of the external power supply. The voltage signal acquisition terminal of the voltage sampling module 3 is connected to the live wire output terminal of the input protection module 2. The voltage divider signal output terminal of the voltage sampling module 3 is connected to the inverting input terminal of the reference comparison module 4. The reference voltage input terminal of the reference comparison module 4 is connected to the reference output terminal of the independent reference voltage source. The overvoltage status output terminal of the reference comparison module 4 is connected to the trigger signal input terminal of the delay judgment module 5. The delay action output terminal of the delay judgment module 5 is connected to the drive control terminal of the trip execution module 6. The output terminal of the trip execution module 6 is connected to the input terminal of the trip unit 101.

[0029] The input protection module 2 includes a transient suppression diode. The cathode of the transient suppression diode is connected to the live wire terminal of the external power supply, and the anode of the transient suppression diode is connected to the neutral wire terminal of the external power supply.

[0030] The voltage sampling module 3 includes a first voltage divider resistor and a second voltage divider resistor. One end of the first voltage divider resistor is connected to the cathode of the transient suppression diode in the input protection module 2. The other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor and the inverting input terminal of the reference comparison module 4. The other end of the second voltage divider resistor is grounded.

[0031] The reference comparison module 4 includes a TL431 reference voltage source chip and an LM393 voltage comparator. The anode of the TL431 reference voltage source chip is grounded, and the cathode of the TL431 reference voltage source chip is connected to the first current limiting resistor. The first inverting input terminal of the LM393 voltage comparator is connected to the voltage divider output terminal of the voltage sampling module 3, and the first output terminal of the LM393 voltage comparator is connected to the trigger signal input terminal of the delay judgment module 5.

[0032] The delay judgment module 5 includes a delay resistor, a delay capacitor, and a threshold voltage divider network. One end of the delay resistor is connected to the first output terminal of the LM393 voltage comparator, and the other end of the delay resistor is connected to the positive terminal of the delay capacitor and the second inverting input terminal of the LM393 voltage comparator. The negative terminal of the delay capacitor is grounded. The second output terminal of the LM393 voltage comparator is connected to the drive control terminal of the trip execution module 6. The threshold voltage divider network includes a pull-up resistor and a pull-down resistor. One end of the pull-up resistor is energized, and the other end of the pull-up resistor is connected in series with the pull-down resistor and then grounded. The second non-inverting input terminal of the LM393 voltage comparator is connected to the connection node between the pull-up resistor and the pull-down resistor.

[0033] The tripping execution module 6 includes a driving transistor, a single-pole double-throw relay, and a freewheeling protection diode. The base of the driving transistor is connected to the second output terminal of the LM393 voltage comparator in the reference comparison module 4 through a second current-limiting resistor. The emitter of the driving transistor is grounded. The collector of the driving transistor is connected to the coil of the single-pole double-throw relay and then energized. The common terminal of the contacts of the single-pole double-throw relay is used to connect to an external tripping power supply. The normally open terminal of the contacts of the single-pole double-throw relay is connected to the trip unit 101. The anode of the freewheeling diode is connected to the collector of the driving transistor, and the cathode of the freewheeling diode is energized.

[0034] When the transient overvoltage identification circuit works in conjunction with the protector, the live wire terminal and the neutral wire terminal of the external power supply are connected to the cathode and anode of the transient suppression diode of the input protection module 2. When the power grid encounters lightning induction, operational overvoltage or neutral wire breakage fault, if the transient voltage exceeds the 440-volt clamping value, the transient suppression diode will immediately conduct to discharge energy and limit the live wire voltage to a safe range.

[0035] Meanwhile, the first voltage divider resistor of voltage sampling module 3 obtains the real-time voltage from the cathode of transient suppression diode. Through the voltage divider network composed of the first and second voltage dividers, a proportionally reduced sampling signal is generated at the voltage divider output. When the mains voltage continuously exceeds the 275V threshold, the voltage at the voltage divider output exceeds 2.5V and is transmitted to the first inverting input of the LM393 voltage comparator in reference comparison module 4. The reference voltage source chip provides a precise 2.5V reference to the non-inverting input of the first voltage comparator unit through the reference pin. When the voltage at the inverting input is higher than that at the non-inverting input, the first output of the LM393 voltage comparator jumps from high level to low level. This jump signal is input to the delay resistor signal input of delay judgment module 5.

[0036] The delay resistor and delay capacitor form a time constant circuit. A low-level signal continuously discharges through the delay resistor to the positive plate of the delay capacitor, causing the voltage at the second inverting input of the LM393 voltage comparator to decrease slowly. Meanwhile, the second non-inverting input of the LM393 voltage comparator is connected to the threshold voltage generated by the pull-up and pull-down resistors. If the overvoltage duration is less than x seconds, the voltage at the inverting input is still higher than that at the non-inverting input, and the second output of the LM393 voltage comparator remains high.

[0037] When the overvoltage condition of the power grid continues for more than x seconds, the voltage of the positive plate of the delay capacitor drops below 2.5 volts, triggering the second output of the LM393 voltage comparator to flip to a low level. This low-level signal is transmitted to the base of the driving transistor of the trip execution module 6 through the second current-limiting resistor, causing the driving transistor to switch from the cutoff state to the on state.

[0038] The collector current of the driving transistor activates the coil of the single-pole double-throw relay, and its normally open contact closes to form a current path, connecting the positive terminal of the external trip power supply to the trip unit 101. The trip unit 101 then completes its operation and disconnects the power.

[0039] A freewheeling protection diode is connected in parallel across the coil of the single-pole double-throw relay. Its cathode is connected to the power supply to absorb the reverse electromotive force generated when the coil is de-energized, ensuring that the driving transistor is not damaged. During this process, if the overvoltage is transient, the voltage of the RC network will always be higher than the threshold, the second output of the LM393 voltage comparator will not have any output action, and the single-pole double-throw relay will remain in the normally open state, effectively preventing the protector from tripping erroneously.

[0040] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A low voltage early warning protector for an electrical circuit, characterized by, The device includes a protector body (1) and a transient overvoltage identification circuit. The protector body (1) includes a trip unit (101). The transient overvoltage identification circuit is electrically connected to the trip unit (101). The transient overvoltage identification circuit detects the input overvoltage state by comparing the voltage divider sampling with the reference voltage and uses a resistor-capacitor delay network to distinguish between transient overvoltage and continuous overvoltage. The trip unit (101) is triggered after the overvoltage exceeds the threshold for more than x seconds.

2. A low voltage warning protector for a circuit according to claim 1, wherein, The instantaneous overvoltage identification circuit includes an input protection module (2), a voltage sampling module (3), a reference comparison module (4), a delay judgment module (5), and a trip execution module (6). The AC power live wire input terminal of the input protection module (2) is used for the live wire terminal of the external power supply. The AC power neutral wire input terminal of the input protection module (2) is connected to the neutral wire terminal of the external power supply. The voltage signal acquisition terminal of the voltage sampling module (3) is connected to the live wire output terminal of the input protection module (2). The voltage divider signal output terminal of the voltage sampling module (3) is connected to the inverting input terminal of the reference comparison module (4). The reference voltage input terminal of the reference comparison module (4) is connected to the reference output terminal of the independent reference voltage source. The overvoltage state output terminal of the reference comparison module (4) is connected to the trigger signal input terminal of the delay judgment module (5). The delay action output terminal of the delay judgment module (5) is connected to the drive control terminal of the trip execution module (6). The output terminal of the trip execution module (6) is connected to the input terminal of the trip unit (101).

3. A low voltage warning protector for a circuit according to claim 2, wherein The input protection module (2) includes a transient suppression diode, the cathode of which is connected to the live wire terminal of the external power supply, and the anode of which is connected to the neutral wire terminal of the external power supply.

4. The low-voltage warning protector for a circuit according to claim 2, wherein The voltage sampling module (3) includes a first voltage divider resistor and a second voltage divider resistor. One end of the first voltage divider resistor is connected to the cathode of the transient suppression diode in the input protection module (2). The other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor and the inverting input terminal of the reference comparison module (4). The other end of the second voltage divider resistor is grounded.

5. The low voltage warning protector for circuit according to claim 2, characterized in that, The reference comparison module (4) includes a TL431 reference voltage source chip and an LM393 voltage comparator. The anode of the TL431 reference voltage source chip is grounded, and the cathode of the TL431 reference voltage source chip is connected to the power supply through a first current limiting resistor. The first inverting input terminal of the LM393 voltage comparator is connected to the voltage divider output terminal of the voltage sampling module (3), and the first output terminal of the LM393 voltage comparator is connected to the trigger signal input terminal of the delay judgment module (5).

6. A low voltage warning protector for a circuit according to claim 5, wherein, The delay judgment module (5) includes a delay resistor, a delay capacitor, and a threshold voltage divider network. One end of the delay resistor is connected to the first output terminal of the LM393 voltage comparator, and the other end of the delay resistor is connected to the positive terminal of the delay capacitor and the second inverting input terminal of the LM393 voltage comparator. The negative terminal of the delay capacitor is grounded. The second output terminal of the LM393 voltage comparator is connected to the drive control terminal of the trip execution module (6). The threshold voltage divider network includes a pull-up resistor and a pull-down resistor. One end of the pull-up resistor is energized, and the other end of the pull-up resistor is connected in series with the pull-down resistor and then grounded. The second non-inverting input terminal of the LM393 voltage comparator is connected to the connection node between the pull-up resistor and the pull-down resistor.

7. The low voltage warning protector for circuit according to claim 2, wherein, The tripping execution module (6) includes a driving transistor, a single-pole double-throw relay, and a freewheeling diode. The base of the driving transistor is connected to the second output terminal of the LM393 voltage comparator in the reference comparison module (4) through a second current-limiting resistor. The emitter of the driving transistor is grounded. The collector of the driving transistor is connected to the coil of the single-pole double-throw relay and then energized. The common terminal of the contacts of the single-pole double-throw relay is used to connect to an external tripping power supply. The normally open terminal of the contacts of the single-pole double-throw relay is connected to the trip unit (101). The anode of the freewheeling diode is connected to the collector of the driving transistor, and the cathode of the freewheeling diode is energized.

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