A low-power surge protector state monitoring device, method and system

Abstract

The application relates to the technical field of lightning protection of low-voltage power distribution systems, and discloses a low-power surge protector state monitoring device, method and system.The device comprises a current transformer clamped on a surge protector grounding wire; a first detection branch connected with a secondary coil of the current transformer and provided with a comparator for outputting a wake-up signal when a power frequency current exceeds a preset threshold; a second detection branch connected with the secondary coil of the current transformer and provided with a signal injection unit and a signal detection unit for judging the on-off state of a grounding loop; a microcontroller in a deep sleep state under normal conditions; an alarm unit for outputting an alarm signal; and a power supply unit powered by a button cell.The application adopts a hybrid architecture of a comparator for continuous monitoring and a MCU for deep sleep, and the whole machine has low standby power consumption; the power frequency current monitoring and the grounding on-off detection are realized through a single secondary coil, and the application is suitable for wiring-free reconstruction of a stock distribution box.

Description

Technical Field

[0001] This invention relates to the field of lightning protection technology for low-voltage power distribution systems, and in particular to a low-power surge protector status monitoring device, method, and system. Background Technology

[0002] Surge protectors (SPDs) are key protective components in low-voltage power distribution systems used to limit transient overvoltages and discharge lightning currents. When an SPD fails due to long-term deterioration or lightning damage, a continuous power frequency follow current will be generated on its grounding wire (PE wire). If not detected in time, it may cause the SPD to overheat and catch fire, leading to a serious safety accident.

[0003] However, existing technologies still have the following problems: 1. Existing SPD monitoring devices mostly adopt the MCU periodic wake-up sampling scheme, which requires periodic wake-up for ADC sampling and data processing. The standby power consumption is usually in the tens of microamps to milliamps range, requiring an external power supply or frequent battery replacement, which is not suitable for the wiring-free transformation of existing distribution boxes.

[0004] 2. Existing SPD monitoring devices have fixed functions and cannot be flexibly configured with different combinations of functions such as local alarm, remote signaling input, and wireless communication according to user needs, making it difficult to cover the multi-level market demand from basic stock upgrades to high-end intelligent monitoring. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a low-power surge protector status monitoring device, method, and system, which solves the problems of high power consumption and inability to achieve long-term power supply from button batteries in existing monitoring devices, as well as the problems of high hardware costs and limited product form due to the separation of power frequency current monitoring and grounding detection.

[0006] Firstly, in order to achieve the above objectives, the present invention adopts the following technical solution: A low-power surge protector status monitoring device, method, and system, comprising: a current transformer, wherein the current transformer is clamped to the grounding wire of the surge protector; The first detection branch is connected to the secondary coil of the current transformer. A comparator is provided on the first detection branch. The comparator is used to detect the power frequency current on the grounding wire in real time and output a wake-up signal when the power frequency current exceeds a preset threshold. The second detection branch is connected to the secondary coil of the current transformer. The second detection branch is equipped with a signal injection unit and a signal detection unit. The signal injection unit is used to inject a detection signal into the grounding wire, and the signal detection unit is used to receive the return signal of the detection signal and determine whether the grounding loop is normal based on the return signal. The microcontroller has a wake-up pin connected to the output of the comparator. The microcontroller is in a deep sleep state under normal conditions and is woken up when it receives the wake-up signal. An alarm unit, controlled by a microcontroller, is used to issue alarm signals; A power supply unit is used to supply power to the various components of the device.

[0007] Furthermore, the microcontroller is connected to a self-test button and a reset button. When the self-test button is pressed briefly, it triggers a single grounding continuity test. When the self-test button is pressed for a long time, it triggers an analog power frequency current alarm. When the reset button is pressed briefly, it illuminates an indicator light. When the reset button is pressed for a long time, it clears the alarm self-locking state.

[0008] Furthermore, the microcontroller is connected to a low-battery detection unit, which is used to detect the battery voltage of the power supply unit; the signal input pin of the microcontroller is connected to a digital input interface, which is used to connect to the remote signaling terminal of the surge protector or the auxiliary contact of the surge backup protector.

[0009] Furthermore, the microcontroller is connected to a wireless communication module, which is used to upload alarm information to a gateway or remote terminal.

[0010] Furthermore, a sampling resistor is provided on the first detection branch, and the sampling resistor is connected in parallel across the secondary coil of the current transformer.

[0011] Furthermore, the frequency of the detection signal injected by the signal injection unit is from 0.5kHz to 5kHz; when the amplitude of the returned signal decreases to below a preset threshold or disappears, the grounding circuit is determined to be abnormal. The criterion for determining the grounding circuit to be abnormal is that the circuit impedance is greater than or equal to 1kΩ.

[0012] Secondly, in order to achieve the above objectives, the present invention adopts the following technical solution: A low-power surge protector status monitoring method, characterized by comprising the following steps: The current transformer senses the current signal on the grounding wire of the surge protector, injects a detection signal into the grounding wire, and receives the return signal of the detection signal. The comparator is used to monitor the current signal in real time. When the power frequency current value corresponding to the current signal exceeds a preset threshold, the comparator outputs a wake-up signal and wakes up the microcontroller. After the microcontroller is woken up, it continuously samples the power frequency current and determines whether the duration for which the power frequency current exceeds a preset threshold has reached a set value. An alarm is triggered when the duration reaches the set value; When the power frequency current disappears within the set value, no alarm is triggered, and the microcontroller re-enters deep sleep mode.

[0013] Furthermore, the microcontroller periodically wakes up from deep sleep mode and determines whether the grounding loop is abnormal based on the amplitude of the returned signal; when an abnormality is detected, an alarm is triggered after multiple consecutive abnormal detections; when the detection result is normal, the microcontroller enters deep sleep mode under normal conditions.

[0014] Thirdly, in order to achieve the above objectives, the present invention adopts the following technical solution: A low-power surge protector status monitoring system, characterized in that it comprises: A low-power surge protector status monitoring device; The gateway is wirelessly connected to the monitoring device. The cloud platform is communicatively connected to the gateway; User terminal, which is communicatively connected to the cloud platform; When the monitoring device triggers an alarm, the gateway uploads the alarm information to the cloud platform, and the cloud platform pushes the alarm information to the user terminal.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention employs a hybrid architecture that combines continuous monitoring by a comparator with deep sleep mode of a microcontroller. Under normal conditions, the microcontroller is in deep sleep mode and is only awakened by a wake-up signal output by a hardware comparator when the power frequency current exceeds a preset threshold. It has low power consumption, requires no external power supply or frequent battery replacement, and does not require regular inspection and maintenance. It is suitable for the no-wiring renovation of existing building distribution boxes.

[0016] 2. This invention achieves both power frequency current monitoring and grounding continuity detection using a single current transformer. Power frequency current monitoring utilizes a power frequency signal converted into voltage by a sampling resistor and then detected in real time by a comparator. Grounding continuity detection injects a detection signal into the same transformer and receives a return signal. By utilizing the frequency separation principle, the two detection functions can share the same transformer, reducing hardware costs and installation complexity, and enabling the device to achieve more comprehensive monitoring capabilities in a smaller size.

[0017] 3. This invention adopts a modular architecture design. Based on the core monitoring function, the switch input interface and wireless communication module can be flexibly configured according to user needs, forming a variety of product forms such as basic version, remote signaling version, wireless version, and remote signaling and wireless. This meets the multi-level market demand from basic existing equipment renovation to high-end intelligent monitoring, while significantly reducing product development and maintenance costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a low-power surge protector status monitoring device proposed in this invention; Figure 2 This is a schematic diagram of another perspective of the low-power surge protector status monitoring device proposed in this invention. Figure 3 This is a schematic diagram of the internal structure of a low-power surge protector status monitoring device proposed in this invention. Figure 4 The schematic diagram of the power frequency current monitoring circuit for a low-power surge protector status monitoring method proposed in this invention is shown. Figure 5 This is a schematic diagram illustrating the grounding continuity detection principle of a low-power surge protector status monitoring method proposed in this invention. Figure 6 This is a standby power consumption management state transition diagram for a low-power surge protector state monitoring method proposed in this invention.

[0019] Explanation of the labels in the diagram: 1. Current transformer; 2. First detection branch; 3. Second detection branch; 4. Microcontroller; 5. Self-test button; 6. Reset button; 7. Alarm unit; 8. Power supply unit. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example 1, please refer to Figures 1 to 6 This is the first embodiment of the present invention. This embodiment provides a low-power surge protector status monitoring device, which includes a current transformer 1, a first detection branch 2, a second detection branch 3, a microcontroller 4, an alarm unit 7, and a power supply unit 8.

[0022] Current transformer 1 is clamped to the PE grounding wire of the surge protector. When the SPD fails due to a short circuit, the power frequency freewheeling current flowing on the PE wire induces a corresponding current signal in the secondary coil of current transformer 1. The sampling resistor connected to the secondary coil of current transformer 1 is grounded, converting the secondary current signal into a voltage signal.

[0023] The first detection branch 2 is connected to the secondary coil of the current transformer 1. A comparator is provided on the first detection branch 2. The non-inverting input terminal of the comparator is connected to the connection node between the sampling resistor and the secondary coil of the current transformer 1, and the inverting input terminal is connected to a preset threshold voltage source. The preset threshold voltage source is generated by the 1.242V reference inside the TLV3011 through an external resistor voltage divider network, and its output voltage does not change with the battery voltage of the power supply unit 8.

[0024] In this embodiment, when the primary power frequency current reaches 100mA, the secondary current is 0.1mA, generating a 10mV voltage signal on the 100Ω sampling resistor. This voltage exceeds the threshold voltage of the inverting input of the comparator, causing the comparator output to flip and generate a wake-up signal. The output of the comparator is connected to the external interrupt pin of the microcontroller 4.

[0025] The second detection branch 3 is connected to the secondary coil of the current transformer 1. The second detection branch 3 is equipped with a signal injection unit and a signal detection unit. The signal injection unit generates a 1kHz square wave signal from the GPIO pin of the microcontroller 4, injects it into the secondary coil of the current transformer 1 through a current limiting resistor, and then couples it to the PE line through the transformer. The signal detection unit acquires the amplitude of the return signal through the ADC pin of the microcontroller 4. When the PE circuit is complete, the injected 1kHz signal forms a loop through the PE line, and the amplitude of the return signal is within the normal range. When the PE circuit is broken or the circuit impedance increases to more than 1kΩ, the amplitude of the return signal drops significantly or disappears completely.

[0026] The wake-up pin of microcontroller 4 is connected to the comparator output, and the other GPIO pins are connected to alarm unit 7 and expansion interface respectively. Under normal conditions, microcontroller 4 is in deep sleep mode. When the comparator output flips, a rising edge interrupt is generated, which wakes up microcontroller 4.

[0027] The alarm unit 7 includes LED indicators and a buzzer, which are controlled by the GPIO pins of the microcontroller 4. The LED indicators include at least red LEDs and green LEDs. The red LEDs are used to indicate power frequency current fault alarms, and the green LEDs are used to indicate normal operation and equipment location.

[0028] Power unit 8 is powered by a single CR2032 button cell battery with a nominal voltage of 3V. The standby power consumption of the whole device is no more than 10µA, and a single battery can support the device to work continuously for 2.5 to 3 years.

[0029] The working process of power frequency current monitoring is explained below.

[0030] Under normal conditions, there is no power frequency current on the PE line, the secondary coil of current transformer 1 has no induced signal, the comparator output remains low, and microcontroller 4 is in deep sleep mode. When the SPD fails due to a short circuit, power frequency current begins to flow through the PE line; when the primary current reaches 100mA, the 10mV voltage signal generated by the secondary current through the sampling resistor exceeds the comparator threshold, the comparator output flips, and a rising edge signal wakes up microcontroller 4.

[0031] After waking up, microcontroller 4 immediately starts ADC sampling, continuously sampling the comparator input signal at a sampling rate of not less than 1kHz for a duration of 100ms. Microcontroller 4 calculates the effective value of the sampled signal to determine whether the power frequency current persists. If the current exceeds the threshold for 100ms, microcontroller 4 determines it to be a real power frequency fault, controls the red LED to remain lit, drives the buzzer to emit a continuous alarm sound, and simultaneously enters an alarm self-locking state. If the current disappears within 100ms, microcontroller 4 determines the signal to be transient interference such as a lightning pulse, does not trigger an alarm, clears the ADC sampling buffer, and re-enters deep sleep mode.

[0032] The working process of grounding continuity detection is explained below.

[0033] Microcontroller 4 automatically wakes up every 10 minutes, outputting a 1kHz square wave signal through its GPIO pin. This signal is injected into the secondary coil of current transformer 1 via a current-limiting resistor and then coupled into the PE line through the transformer. Microcontroller 4 then switches to ADC sampling mode to acquire the amplitude of the returned signal. It performs three consecutive checks. If all three results are deemed abnormal, a PE circuit fault is confirmed, the yellow LED illuminates, and an alarm latch is triggered. If any of the three checks are normal, the result is considered interference and ignored, and microcontroller 4 re-enters deep sleep mode.

[0034] Example 2: Based on Example 1, this example adds a self-test button 5, a reset button 6, a low battery detection unit, and a switch input interface.

[0035] The self-test button 5 and reset button 6 are connected to the signal input pins of the microcontroller 4 for manual triggering by the operator. When the self-test button 5 is short-pressed, the microcontroller 4 immediately performs a grounding continuity test. After the test, if the grounding is normal, the green LED flashes twice; if the grounding is abnormal, the yellow LED lights up and the alarm continues. When the self-test button 5 is pressed for more than 3 seconds, it simulates a power frequency current alarm state, and the red LED lights up to indicate this. Releasing the button stops the alarm; it does not self-lock, and is used to verify the normal operation of the audible and visual alarm function on-site. When the reset button 6 is short-pressed, the green LED lights up, used to confirm the location of the equipment in the distribution box; when the reset button 6 is pressed for more than 3 seconds, it clears all alarm self-lock states, restoring the device to normal monitoring status.

[0036] The low battery detection unit is connected to the microcontroller 4 and is used to detect the battery voltage of the power supply unit 8. The low battery detection unit consists of a resistor voltage divider network, and the voltage divider node is connected to the ADC sampling pin of the microcontroller 4. When the battery voltage is lower than 2.4V, the microcontroller 4 controls the green LED to flash rapidly, and at the same time the buzzer sounds briefly every 30 seconds to remind the user to replace the battery.

[0037] The digital input interface is connected to the signal input pin of the microcontroller 4. Electrical isolation is achieved using an optocoupler isolation circuit. The input terminal of the digital input interface is connected to the internal thermal trip remote signaling terminal of the SPD or the auxiliary contact of the surge backup protector (SCB). When the SPD thermally trips or the SCB trips, the dry contact signal flips, the optocoupler output level changes, and triggers the GPIO interrupt of the microcontroller 4. After the microcontroller 4 is woken up, it executes the alarm logic, controls the yellow LED to light up and self-lock.

[0038] Example 3: This example provides a low-power surge protector status monitoring system, which includes a monitoring device, a gateway, a cloud platform, and a user terminal; wherein the monitoring device adds a wireless communication module based on Example 1 or Example 2.

[0039] The wireless communication module uses LoRa communication and connects to the microcontroller 4 via a UART interface to upload alarm information to the gateway or remote terminal. When the microcontroller 4 triggers an alarm, it encapsulates the alarm information into a LoRa data packet, which includes the device ID, alarm type, and alarm timestamp. The data packet is then sent to the gateway via the wireless communication module.

[0040] The gateway receives LoRa data packets sent by the monitoring device and uploads the alarm information to the cloud platform via 4G network or Ethernet. The cloud platform stores and parses the alarm information and pushes it to the user terminal according to the preset push rules. The user terminal is a mobile phone or computer with a corresponding application installed. The user can view the alarm information in real time through the application.

[0041] All four product forms described above can be implemented based on the system described in this embodiment. The basic version only includes the core monitoring function, the remote signaling version adds a switch input interface on the basis of the core, the wireless version adds a wireless communication module, and the complete version includes both switch input and wireless communication. The structure and function of the monitoring device corresponding to each product form have been described in Embodiments 1 and 2. This embodiment focuses on describing the working process in the network application scenario.

[0042] In practical deployment, maintenance personnel install monitoring devices inside the distribution boxes of existing buildings. Current transformer 1 is clamped to the PE grounding wire of the SPD, and the device itself is fixed to the inner wall of the distribution box with screws. When the SPD fails and generates power frequency follow current, the monitoring device locally issues an audible and visual alarm. Simultaneously, it uploads the alarm information to the gateway via a wireless communication module. The gateway then pushes the alarm information to the cloud platform via the 4G network. The cloud platform then pushes the alarm information to the maintenance personnel's mobile terminals. Based on the alarm information, the maintenance personnel locate the specific distribution box and the specific SPD, and promptly replace the failed SPD.

[0043] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A low-power surge protector status monitoring device, characterized in that, include: Current transformer (1), which is clamped to the grounding wire of the surge protector; The first detection branch (2) is connected to the secondary coil of the current transformer (1). A comparator is provided on the first detection branch (2). The comparator is used to detect the power frequency current on the grounding wire in real time and output a wake-up signal when the power frequency current exceeds a preset threshold. The second detection branch (3) is connected to the secondary coil of the current transformer (1). The second detection branch (3) is provided with a signal injection unit and a signal detection unit. The signal injection unit is used to inject a detection signal into the grounding wire. The signal detection unit is used to receive the return signal of the detection signal and determine whether the grounding circuit is normal based on the return signal. Microcontroller (4), the wake-up pin of the microcontroller (4) is connected to the output of the comparator, the microcontroller (4) is in a deep sleep state under normal conditions, and is woken up when the wake-up signal is received; An alarm unit (7) is controlled by a microcontroller (4) and is used to issue an alarm signal. Power supply unit (8) is used to supply power to the various components of the device.

2. The low-power surge protector status monitoring device according to claim 1, characterized in that, The microcontroller (4) is connected to a self-test button (5) and a reset button (6). When the self-test button (5) is pressed briefly, it triggers a single grounding continuity test. When the self-test button (5) is pressed for a long time, it triggers an analog power frequency current alarm. When the reset button (6) is pressed briefly, it lights up an indicator light. When the reset button (6) is pressed for a long time, it clears the alarm self-locking state.

3. The low-power surge protector status monitoring device according to claim 1, characterized in that, The microcontroller (4) is connected to a low power detection unit, which is used to detect the battery voltage of the power supply unit (8); the signal input pin of the microcontroller (4) is connected to a switch input interface, which is used to connect to the remote signaling terminal of the surge protector or the auxiliary contact of the surge backup protector.

4. The low-power surge protector status monitoring device according to claim 1, characterized in that, The microcontroller (4) is connected to a wireless communication module, which is used to upload alarm information to a gateway or remote terminal.

5. The low-power surge protector status monitoring device according to claim 1, characterized in that, The first detection branch (2) is provided with a sampling resistor, which is connected in parallel across the secondary coil of the current transformer (1).

6. A low-power surge protector status monitoring device according to claim 1, characterized in that, The frequency of the detection signal injected by the signal injection unit is from 0.5kHz to 5kHz; when the amplitude of the returned signal decreases to below a preset threshold or disappears, the grounding circuit is determined to be abnormal. The criterion for judging the grounding circuit abnormality is that the circuit impedance is greater than or equal to 1kΩ.

7. A low-power surge protector status monitoring method, characterized in that, Includes the following steps: The current signal on the grounding wire of the surge protector is sensed by the current transformer (1); A detection signal is injected into the grounding wire, and a return signal of the detection signal is received; The comparator is used to monitor the current signal in real time. When the power frequency current value corresponding to the current signal exceeds the preset threshold, the comparator outputs a wake-up signal and wakes up the microcontroller (4). After the microcontroller (4) is woken up, it continuously samples the power frequency current and determines whether the duration of the power frequency current exceeding the preset threshold has reached the set value. An alarm is triggered when the duration reaches the set value; When the power frequency current disappears within the set value, no alarm is triggered, and the microcontroller (4) re-enters deep sleep state.

8. The low-power surge protector status monitoring method according to claim 7, characterized in that, The microcontroller (4) wakes up from deep sleep state at regular intervals and determines whether the grounding circuit is abnormal based on the amplitude of the returned signal. When it is determined to be abnormal, it triggers an alarm after repeatedly detecting abnormality multiple times. When the detection result is normal, the microcontroller (4) enters deep sleep state under normal conditions.

9. A low-power surge protector status monitoring system, characterized in that, include: A low-power surge protector status monitoring device according to any one of claims 1 to 6; The gateway is wirelessly connected to the monitoring device. The cloud platform is communicatively connected to the gateway; User terminal, which is communicatively connected to the cloud platform; When the monitoring device triggers an alarm, it uploads the alarm information to the cloud platform through the gateway, and the cloud platform pushes the alarm information to the user terminal.

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