A new three-wire dual power supply safety circuit system

Abstract

This invention relates to the field of power supply circuit technology, and in particular to a novel three-wire dual-power safety circuit system. The technical solution includes a power supply module and a leakage protection module. The power supply module includes an AC-to-low-voltage DC power conversion circuit and a rectifier bridge. The power supply module outputs low-voltage DC power with positive and negative terminals. The positive terminal is connected to the input ground wire through a first varistor and serves as the ground wire output carrying low-voltage DC power. The negative terminal is connected to the input neutral wire. A first overcurrent circuit breaker is connected to the output terminal of the rectifier bridge. The input live wire and neutral wire pass through a second overcurrent circuit breaker and then serve as the output live wire and neutral wire. The advantages are: by adding a low-voltage DC circuit and utilizing the existing ground and neutral wires as the output circuit for the low-voltage DC power supply, dual power supply is provided in a three-wire household power supply system. This allows direct power supply to smart homes requiring both AC and low-voltage DC power, expanding the function of the ground wire and improving its utilization rate.

Description

Technical Field

[0001] This invention relates to the field of power supply circuit technology, and in particular to a novel three-wire dual-power safety circuit system. Background Technology

[0002] Currently, household power supply primarily uses a three-wire system consisting of a live wire, a neutral wire, and a ground wire. In commonly used household power supply systems, protection is limited to overcurrent circuit breakers at the live and neutral input wires. Therefore, this system only protects against overcurrent, overload, short circuit, and leakage current, lacking the ability to detect abnormalities in the entire power supply system, and also lacks leakage current self-test protection, neutral wire breakage protection, and partial overload protection. Specifically, the following situations illustrate this: 1. When a low-power distribution line is mistakenly connected to a high-power load in a circuit, an overload will occur in the line. The overcurrent circuit breaker at the front end will not be triggered to disconnect because it does not reach the protection current. Continuous power supply will lead to a fire hazard in the overloaded line.

[0003] 2. When the neutral wire in a circuit is old, loose, or broken, the increased resistance of the loose wire will cause it to heat up and damage the connection point, which will also cause the neutral wire to become live. The connected electrical equipment will also become live, thus posing a risk of electric shock to people.

[0004] 3. When an abnormal grounding point occurs in the circuit, the leakage current on the casing of the electrical equipment cannot discharge to the ground, thus posing a risk of electric shock to people.

[0005] 4. In commonly used household power supply systems, the ground wire is only used for ground protection, and its purpose is relatively simple. This leads users to have a disregard for the protection of the ground wire. Some users even abandon the use of the ground wire and only use a two-wire power supply system with a live wire and a neutral wire. This results in the metal casing of some electrical equipment being electrified, which can release current through the human body, increasing the probability of contact accidents. Summary of the Invention

[0006] The purpose of this invention is to provide a novel three-wire dual-power safety circuit system, specifically a circuit system that utilizes the ground and neutral wires to provide an additional low-voltage DC power supply and can effectively protect against various abnormalities or faults in the power supply system.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a novel three-wire dual-power safety circuit system, comprising a power supply module and a leakage protection module. The power supply module includes an AC-to-low-voltage DC power conversion circuit and a rectifier bridge. The output live wire and output neutral wire are connected to the input terminal of the AC-to-low-voltage DC power conversion circuit. The output terminal of the AC-to-low-voltage DC power conversion circuit outputs the positive and negative terminals of low-voltage DC power through the rectifier bridge. The positive terminal of the low-voltage DC power is connected to the ground wire of the mains input through a first varistor and serves as the ground wire output carrying low-voltage DC power. The negative terminal of the low-voltage DC power is connected to the neutral wire of the mains input. A first overcurrent circuit breaker is connected to the positive and negative terminals of the low-voltage DC power. The live wire and neutral wire of the mains input are connected to the output live wire and output neutral wire after passing through a second overcurrent circuit breaker. The first varistor, the first overcurrent circuit breaker, and the second overcurrent circuit breaker constitute the leakage protection module.

[0008] Furthermore, the leakage protection module also includes a negative charge release circuit, which consists of a resistor and a capacitor connected in parallel and then connected in series with a diode. The negative charge release circuit is connected between the positive terminal of the low-voltage DC power supply and the neutral line of the AC mains input.

[0009] Furthermore, the power module also includes a negative charge leakage current detection circuit, which includes a pulse square wave driver and an IGBT field-effect transistor. The output of the AC to low-voltage DC power conversion circuit is connected to the pulse square wave driver and the output is connected to the control terminal of the IGBT field-effect transistor. The IGBT field-effect transistor is connected in series with the output of the rectifier bridge.

[0010] Furthermore, the leakage protection module also includes a low-voltage DC protection circuit, which includes a first rectifier diode, a second rectifier diode, a current-limiting reactor, and a bleeder circuit. The first rectifier diode is connected to the negative terminal of the low-voltage DC power supply, and the second rectifier diode is connected to the positive terminal of the low-voltage DC power supply. The capacitive current of the first rectifier diode flows into the negative terminal of the low-voltage DC power supply, and the capacitive current of the second rectifier diode flows out from the positive terminal of the low-voltage DC power supply. The current-limiting reactor is connected in series at the output terminal of the rectifier bridge. The bleeder circuit includes a transient diode, a bleeder resistor, and a light-emitting diode connected in series, and is connected in parallel at the output terminal of the rectifier bridge.

[0011] Furthermore, the leakage protection module also includes a second varistor, which is connected between the positive terminal of the low-voltage DC power supply and the neutral wire of the AC power input.

[0012] Specifically, a third varistor is connected between the output neutral wire and the ground wire carrying low-voltage DC power.

[0013] Specifically, the third varistor is connected to the output neutral line via an overload fuse.

[0014] Furthermore, it also includes an overload protection circuit, which includes an overload detection circuit and a leakage current triggering circuit. The detection terminal of the overload detection circuit is connected between the output live wire and the load, and the output terminal of the overload detection circuit is connected to the ground wire with low-voltage DC power through the leakage current triggering circuit. The leakage current triggering circuit is composed of a capacitor and a resistor connected in parallel and then a diode connected in series. The leakage current triggering circuit is used to release the negative current on the output live wire.

[0015] Furthermore, the power module is equipped with an alarm circuit, which includes a battery, an electromagnetic relay, a control switch, and an alarm device. The battery is connected to the output terminal of the AC to low-voltage DC power conversion circuit. The battery is also connected in series with the normally closed switch terminal of the electromagnetic relay, the control switch, and the alarm device to form a complete circuit. The coil of the electromagnetic relay is connected between the output live wire and the output neutral wire.

[0016] Furthermore, it also includes an environmental anomaly detection circuit, which includes an environmental detection sensor, a trigger switch, and a leakage current release circuit. The trigger output terminal of the environmental detection sensor is connected to the control terminal of the trigger switch, and the trigger switch and the leakage current release circuit are connected in series between the output live wire and the ground wire with low-voltage DC power.

[0017] The beneficial effects of this invention are as follows: By adding a low-voltage DC circuit and utilizing the existing ground wire and neutral wire as the output circuit of the low-voltage DC power supply, dual power supply can be provided in a three-wire household power supply system. For intelligent control modules in various smart home appliances that require low-voltage DC power supply, there is no need to add an additional adapter power supply to the smart home appliances, and the function of the ground wire can be expanded to improve the utilization rate of the ground wire. At the same time, it also adds detection and protection circuits for neutral wire open circuits and partial line overloads, as well as circuits for detecting and triggering alarms for abnormal situations in the surrounding environment (such as smoke generated by fire, gas leaks, etc.), effectively improving the overall safety protection performance of the circuit system and ensuring the convenience and safety of household electricity use. Attached Figure Description

[0018] Appendix Figure 1 This is a schematic diagram of the overall circuit system in the embodiment; Appendix Figure 2 This is a schematic diagram of a load connection circuit in the embodiment that uses an overload fuse to protect an independent line from overload. Appendix Figure 3 This is a schematic diagram of the load connection circuit using an overload protection circuit in the embodiment. Detailed Implementation

[0019] Example 1, referring to Figure 1-3A novel three-wire dual-power safety circuit system includes a power supply module and a leakage protection module. The power supply module includes an AC-to-low-voltage DC power conversion circuit 11 and a rectifier bridge 12. The output live wire 24 and the output neutral wire 25 are connected to the input terminal of the AC-to-low-voltage DC power conversion circuit 11. The output terminal of the AC-to-low-voltage DC power conversion circuit 11 outputs a low-voltage DC positive terminal 13 and a low-voltage DC negative terminal 14 through the rectifier bridge 12. The low-voltage DC positive terminal 13 is connected to the mains power supply through a first varistor 31. The ground wire 23 of the electrical input is connected and serves as the ground wire 26 output carrying low-voltage DC power. The negative terminal 14 of the low-voltage DC power is connected to the neutral wire 25 of the output. A first overcurrent circuit breaker 41 is connected to the positive terminal 13 and the negative terminal 14 of the low-voltage DC power. The live wire 21 and the neutral wire 22 of the mains power input are connected to the live wire 24 and the neutral wire 25 of the output after passing through the second overcurrent circuit breaker 42. The first varistor 31, the first overcurrent circuit breaker 41 and the second overcurrent circuit breaker 42 constitute the above-mentioned leakage current protection module.

[0020] In this embodiment, the output live wire 24 and the output neutral wire 25 convert 220V AC power to low-voltage DC power through the AC to low-voltage DC power conversion circuit 11, and output the positive terminal 13 and the negative terminal 14 of the low-voltage DC power through the rectifier bridge 12. The positive terminal 13 of the low-voltage DC power is connected to the ground wire of the mains input through the first varistor 31 and serves as the output ground wire 26 carrying low-voltage DC power. During normal power supply, the ground wire 26 carrying low-voltage DC power outputs low-voltage DC power, and the negative terminal 14 of the low-voltage DC power is connected to the output neutral wire 25, thereby enabling the ground wire 26 carrying low-voltage DC power to output low-voltage DC power. A low-voltage DC circuit is formed between ground wire 26 and the output neutral wire 25, allowing for the output of low-voltage DC. At this time, the first varistor 31 connected between the low-voltage DC ground wire 26 and the mains input ground wire 23, since it has not reached its threshold, acts as an open switch. When leakage occurs, causing the low-voltage DC ground wire 26 to carry a higher voltage, the first varistor 31 will conduct, drawing the leakage current out of the mains input ground wire 23. Thus, the low-voltage DC ground wire 26 simultaneously functions as both an output low-voltage DC wire and a general ground wire. When the metal casing of the load is grounded, such as... Figure 2 or Figure 3As shown, because it is connected to the ground wire 26 with low-voltage DC power, to prevent the metal casing of the load from carrying low voltage, a varistor can be connected to the ground wire 26 with low-voltage DC power and then connected to the metal casing of the load. The varistor will only be triggered to conduct and discharge when the metal casing carries a higher voltage. In addition, a first overcurrent circuit breaker 41 is connected to the positive terminal 13 and the negative terminal 14 of the low-voltage DC power supply. It can disconnect when the current in the low-voltage DC power circuit output by the rectifier bridge 2 is too high, thus protecting the rectifier bridge 2 and the AC to low-voltage DC power conversion circuit 1. The second overcurrent circuit breaker 42 connected to the live wire 21 and the neutral wire 22 of the mains input is a generally installed fuse. When leakage, short circuit, overcurrent, or overload occurs, the second overcurrent circuit breaker 42 will be triggered to disconnect, thus protecting the circuit system.

[0021] In a further embodiment, the leakage protection module further includes a low-voltage DC protection circuit 5. The low-voltage DC protection circuit 5 includes a first rectifier diode 51, a second rectifier diode 52, a current-limiting reactor 53, and a bleeder circuit 54. The first rectifier diode 51 is connected to the negative terminal of the low-voltage DC power supply, and the second rectifier diode 52 is connected to the positive terminal 13 of the low-voltage DC power supply. The capacitive current of the first rectifier diode 51 flows into the negative terminal 14 of the low-voltage DC power supply, and the capacitive current of the second rectifier diode 52 flows out from the positive terminal 13 of the low-voltage DC power supply. The current-limiting reactor 53 is connected in series at the output terminal of the rectifier bridge 2. The bleeder circuit 54 includes a transient diode, a bleeder resistor, and a light-emitting diode connected in series, and the bleeder circuit 54 is connected in parallel at the output terminal of the rectifier bridge 2. The low-voltage DC protection circuit 5 is used to protect the low-voltage DC output of the rectifier bridge 12 and the load connected to it. The first rectifier diode 51 and the second rectifier diode 52 can limit the direction of the current flowing through the rectifier bridge 12 to prevent the rectifier bridge 12 from being damaged by reverse high voltage or large current. When the positive terminal 13 of the low-voltage DC is positively charged, it can be released through the ground wire 23 of the mains input. When the positive terminal 13 of the low-voltage DC is negatively charged, it can be released through the second rectifier diode 52, the rectifier bridge 12, the current-limiting reactor 53, the first rectifier diode 51 and the neutral wire 22 of the mains input through the ground wire 23 of the mains input. The current-limiting reactor 53 can limit the current flowing through it to prevent the current from being too large and damaging the rectifier bridge 12. At the same time, the current-draining circuit 54 can assist the current drainage of the rectifier bridge 12, which can effectively stabilize the voltage at the output terminal of the rectifier bridge 12.

[0022] In a further embodiment, the leakage current protection module also includes a negative charge release circuit 6, which consists of a resistor and a capacitor connected in parallel and then connected in series with a diode. The negative charge release circuit 6 is connected between the positive terminal 13 of the low-voltage DC power supply and the neutral wire 22 of the mains input. When the ground wire 23 of the mains input is broken and cannot form a discharge circuit, the negative charge release circuit 6 can guide the negative charge on the ground wire 26 carrying the low-voltage DC power supply to the neutral wire 22 of the mains input, thereby forming a leakage current that triggers the second overcurrent circuit breaker 42 to disconnect for protection. The diode current in the negative charge release circuit 6 flows from the neutral wire 22 of the mains input to the ground wire 26 carrying the low-voltage DC power supply, thereby releasing the negative charge on the ground wire 26 carrying the low-voltage DC power supply. During normal operation of the circuit system, there is no continuity between the ground wire 26 carrying the low-voltage DC power supply and the neutral wire 22 of the mains input. The power module also includes a negative charge leakage current detection circuit 7, which includes a pulse square wave driver 71 and an IGBT field-effect transistor 72. The output of the AC to low voltage DC power conversion circuit 11 is connected to the pulse square wave driver 71 and the output is connected to the control terminal of the IGBT field-effect transistor 72. The IGBT field-effect transistor 72 is connected in series to the output of the rectifier bridge 12. The pulse square wave driver 71 is used to emit a square wave signal with a certain frequency and a certain duty cycle to control the conduction of the IGBT field-effect transistor 72. Preferably, the pulse square wave driver 71 emits a square wave signal with a duty cycle of 99% and a frequency greater than 90Hz. At this time, there will be a 1% open circuit gap in the IGBT field-effect transistor 72. The negative charge release circuit 6 can use the 1% open circuit gap on the IGBT field-effect transistor 72 to detect whether there is a negative charge on the positive terminal 13 of the low-voltage DC power. When the positive terminal 13 of the low-voltage DC power carries a negative charge, the negative charge release circuit 6 can use the 1% open circuit gap on the IGBT field-effect transistor 72 to quickly release the negative charge on the positive terminal 13 of the low-voltage DC power. At the same time, it can also trigger the second overcurrent circuit breaker 42 to open to protect the circuit system. It should be noted that there is a 1% open circuit gap on the IGBT MOSFET 72. Since its switching frequency is relatively high, greater than 90Hz, the time of its 1% open circuit gap is also very short. Its impact on the connected low-voltage DC load can be ignored. At the same time, inductors and capacitors can be connected to the load to eliminate the impact of the open circuit gap.

[0023] In a further embodiment, the leakage current protection module also includes a second varistor 32, which is connected between the positive terminal 13 of the low-voltage DC power supply and the neutral wire 22 of the mains input. The second varistor 32, together with the ground wire 23 of the mains input, can release the leakage current present on the ground wire 26 carrying the low-voltage DC power supply, thereby constructing a dual-wire leakage current protection system. This improves the speed of leakage current release and also allows for leakage current release even when the ground wire 23 of the mains input is broken, effectively enhancing the safety of the circuit system.

[0024] Specifically, a third varistor 33 is connected between the end of the output neutral wire 25 and the ground wire 26 carrying low-voltage DC power; for example Figure 1 As shown in Figure 2 or 3, in a circuit connected to a load, when a break occurs on the output neutral wire 25, a complete circuit cannot be formed at the break point. By setting a third varistor 33 between the end of the output neutral wire 25 and the ground wire 26 with low-voltage DC power, the current on the output live wire 24 can form a circuit through the third varistor 33, the ground wire 26 with low-voltage DC power, the first varistor 31, and the ground wire 23 of the mains input after passing through the load, thereby generating leakage current and triggering the second overcurrent circuit breaker 42 to disconnect, thus protecting the circuit system.

[0025] Reference Figure 2 An overload fuse 81 is also connected to the neutral wire 25. The overload fuse 81 can be triggered to disconnect when the load on the line is too high, thereby triggering the third varistor 33 to generate leakage current, causing the second overcurrent circuit breaker 42 to disconnect. This avoids the problem of fire hazards caused by excessive load in some low-load lines without triggering the second overcurrent circuit breaker 42. The overload fuse 81 is preferably an automatically resettable fuse.

[0026] Additionally, refer to Figure 3 Alternatively, a separate overload protection circuit 8 can be configured. This overload protection circuit 8 includes an overload detection circuit 82 and a leakage current triggering circuit 83. The detection terminal of the overload detection circuit 82 is connected between the output live wire 24 and the load. The output terminal of the overload detection circuit 82 is connected to the ground wire 26 with low-voltage DC power through the leakage current triggering circuit 83. The leakage current triggering circuit 83 consists of a capacitor and a resistor connected in parallel, with a diode connected in series. The leakage current triggering circuit 83 is used to release the negative current on the output live wire 24. The overload detection circuit 82 can employ a three-terminal thermistor. When an overload occurs in the circuit, the three-terminal thermistor 82 generates excessive heat, causing the internal thermistor metal sheet to deform and conduct through the leakage current triggering circuit 83. This, in turn, creates a leakage current through the leakage current triggering circuit 83 and the ground wire 26 with low-voltage DC power, triggering the second overcurrent circuit breaker 42 to disconnect and protect the circuit system.

[0027] In a further embodiment, the power module includes an alarm circuit 9, which comprises a battery 91, an electromagnetic relay 92, a control switch 93, and an alarm device 94. The battery 91 is connected to the output terminal of the AC-to-low-voltage DC power conversion circuit 11. The battery 91 is connected in series with the normally closed switch terminal of the electromagnetic relay 92, the control switch 93, and the alarm device 94 to form a complete circuit. The coil of the electromagnetic relay 92 is connected between the output live wire 24 and the output neutral wire 25. The electromagnetic relay 92, with its coil connected between the output live wire 24 and the output neutral wire 25, can detect whether the second overcurrent circuit breaker 42 has opened. When the second overcurrent circuit breaker 42 opens, the coil of the electromagnetic relay 92 is de-energized, thereby closing the normally closed switch terminal of the electromagnetic relay 92 connected in series in the alarm circuit 9, turning on the alarm circuit 92, and causing the alarm device 94 to issue an alarm signal, reminding relevant personnel to inspect the circuit system. The battery 91 can power the alarm circuit 9, the alarm device 94 can be a buzzer or warning light or other related alarm device that can serve as a warning, and the control switch 93 can disconnect the alarm circuit 9 and stop the alarm after maintenance personnel arrive at the site.

[0028] In a further embodiment, an environmental anomaly detection circuit 10 is also included. The environmental anomaly detection circuit 10 includes an environmental detection sensor 101, a trigger switch 102, and a leakage current release circuit 103. The trigger output terminal of the environmental detection sensor 101 is connected to the control terminal of the trigger switch 102. The trigger switch 102 and the leakage current release circuit 103 are connected in series between the output live wire 24 and the ground wire 26 carrying low-voltage DC power. The environmental anomaly detection circuit 10 can detect abnormal conditions in the surrounding environment and, upon the occurrence of an anomaly, trigger the leakage current to disconnect the second overcurrent circuit breaker 42, thereby triggering the alarm circuit 9 to conduct and issue an alarm signal. The environmental detection sensor 101 can be selected according to the environmental anomalies to be detected, including but not limited to smoke sensors, gas sensors, and temperature sensors. When an abnormal situation occurs in the surrounding environment, the trigger output terminal of the environmental detection sensor 101 sends a signal to the control terminal of the trigger switch 102, thereby turning on the trigger switch 102 and forming a loop between the leakage current release circuit 103, the output live wire 24, and the ground wire 26 carrying low-voltage DC power, releasing the leakage current and triggering the second overcurrent circuit breaker 42 to open. The trigger switch 102 can be a silicon controlled rectifier (SCR).

[0029] Of course, the above are only preferred embodiments of the present invention and are not intended to limit the scope of application of the present invention. Therefore, any equivalent changes made to the principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel three-wire dual power supply safety circuit system, characterized by: The system includes a power supply module and a leakage protection module. The power supply module includes an AC-to-low-voltage DC power conversion circuit and a rectifier bridge. The output live wire and neutral wire are connected to the input terminal of the AC-to-low-voltage DC power conversion circuit. The output terminal of the AC-to-low-voltage DC power conversion circuit outputs a positive terminal and a negative terminal of low-voltage DC power through the rectifier bridge. The positive terminal of the low-voltage DC power is connected to the ground wire of the mains input through a first varistor and serves as a ground wire output carrying low-voltage DC power. The negative terminal of the low-voltage DC power is connected to the neutral wire of the mains input. A first overcurrent circuit breaker is connected to the positive and negative terminals of the low-voltage DC power. The live wire and neutral wire of the mains input pass through the second overcurrent circuit breaker and become the live wire and neutral wire of the output. The first varistor, the first overcurrent circuit breaker, and the second overcurrent circuit breaker constitute the leakage current protection module. It also includes an overload protection circuit, which includes an overload detection circuit and a leakage current triggering circuit. The detection terminal of the overload detection circuit is connected between the output live wire and the load, and the output terminal of the overload detection circuit is connected to the ground wire with low-voltage DC power through the leakage current triggering circuit. The leakage current triggering circuit is composed of a capacitor and a resistor connected in parallel and then a diode connected in series. The leakage current triggering circuit is used to release the negative voltage on the output live wire.

2. The novel three-wire dual-power safety circuit system according to claim 1, characterized in that: The leakage protection module also includes a negative charge release circuit, which is composed of a resistor and a capacitor connected in parallel and then connected in series with a diode. The negative charge release circuit is connected between the positive terminal of the low-voltage DC power supply and the neutral line of the AC mains input.

3. A novel three-wire dual-power safety circuit system according to claim 2, characterized in that: The power module also includes a negative charge leakage current detection circuit, which includes a pulse square wave driver and an IGBT field-effect transistor. The output of the AC to low-voltage DC power conversion circuit is connected to the pulse square wave driver and the output is connected to the control terminal of the IGBT field-effect transistor. The IGBT field-effect transistor is connected in series with the output of the rectifier bridge.

4. The novel three-wire dual-power safety circuit system according to claim 1, characterized in that: The leakage protection module also includes a low-voltage DC protection circuit, which includes a first rectifier diode, a second rectifier diode, a current-limiting reactor, and a bleeder circuit. The first rectifier diode is connected to the negative terminal of the low-voltage DC power supply, and the second rectifier diode is connected to the positive terminal of the low-voltage DC power supply. The capacitive current of the first rectifier diode flows into the negative terminal of the low-voltage DC power supply, and the capacitive current of the second rectifier diode flows out from the positive terminal of the low-voltage DC power supply. The current-limiting reactor is connected in series at the output terminal of the rectifier bridge. The bleeder circuit includes a transient diode, a bleeder resistor, and a light-emitting diode connected in series, and is connected in parallel at the output terminal of the rectifier bridge.

5. A novel three-wire dual-power safety circuit system according to claim 1, characterized in that: The leakage protection module also includes a second varistor, which is connected between the positive terminal of the low-voltage DC power supply and the neutral line of the AC power input.

6. A novel three-wire dual-power safety circuit system according to claim 1, characterized in that: A third varistor is connected between the output neutral line and the ground line carrying low-voltage DC power.

7. A novel three-wire dual-power safety circuit system according to claim 6, characterized in that: The third varistor is connected to the output neutral line via an overload fuse.

8. A novel three-wire dual-power safety circuit system according to any one of claims 1-7, characterized in that: The power module is equipped with an alarm circuit, which includes a battery, an electromagnetic relay, a control switch, and an alarm device. The battery is connected to the output terminal of the AC to low-voltage DC power conversion circuit. The battery is also connected in series with the normally closed switch terminal of the electromagnetic relay, the control switch, and the alarm device to form a complete circuit. The coil of the electromagnetic relay is connected between the output live wire and the output neutral wire.

9. A novel three-wire dual-power safety circuit system according to claim 8, characterized in that: It also includes an environmental anomaly detection circuit, which includes an environmental detection sensor, a trigger switch, and a leakage current release circuit. The trigger output terminal of the environmental detection sensor is connected to the control terminal of the trigger switch. The trigger switch and the leakage current release circuit are connected in series between the output live wire and the ground wire with low-voltage DC power.

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