CN114977090A

CN114977090A - Novel three-wire system dual-power safety circuit system

Info

Publication number: CN114977090A
Application number: CN202210810118.5A
Authority: CN
Inventors: 杨林
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-07-11
Filing date: 2022-07-11
Publication date: 2022-08-30

Abstract

The invention relates to the technical field of power supply circuits, in particular to a novel three-wire system dual-power-supply safety circuit system. The following technical scheme is adopted: the power supply module comprises an AC-to-low voltage DC power supply conversion circuit and a rectifier bridge, the power supply module outputs a positive pole and a negative pole of low voltage DC, the positive pole is connected with an input ground wire through a first voltage dependent resistor and is used as the output of the ground wire with the low voltage DC, and the negative pole is connected with an input zero line; the output end of the rectifier bridge is connected with a first overcurrent breaker, and the input live wire and the input zero wire pass through a second overcurrent breaker and then serve as the output live wire and the output zero wire. Has the advantages that: through installing low pressure DC circuit additional and utilizing current ground wire and zero line as low pressure DC power supply's output circuit, realize providing dual power supply in three-wire system family power supply system, can directly supply power to the intelligent house that needs alternating current and low pressure direct current, realize the function expansion to the ground wire, improve the ground wire rate of utilization.

Description

Novel three-wire system dual-power safety circuit system

Technical Field

The invention relates to the technical field of power supply circuits, in particular to a novel three-wire dual-power-supply safety circuit system.

Background

At present, a three-wire system power supply system consisting of a live wire, a zero wire and a ground wire is basically adopted for household power supply, and in a household power supply system commonly used at present, the protection of the power supply system is only stopped at the positions of the live wire and the zero wire input at the front end to be provided with an overcurrent breaker for protection, so that the household power supply system has a protection function only on the conditions of overcurrent, overload, short circuit, contact leakage and the like, does not have the sensing capability of the circuit abnormity of the whole power supply system, and also does not have the functions of leakage self-detection protection, zero wire open circuit protection and partial line overload protection. Specifically, the following are the cases:

1. when a distribution line with low bearing power is connected to a high-power load by mistake in a circuit, an overload condition can occur in the line, the overcurrent breaker at the front end cannot be triggered to be disconnected because the overcurrent breaker cannot reach the protection current, and the fire hazard can occur to the overloaded line due to continuous power supply.

2. When appearing ageing virtual connection of zero line and break circuit in the circuit, the increase of not hard up line resistance can generate heat and damage the butt joint and also can lead to the zero line electrified, thereby the consumer of butt joint also can be electrified to produce the danger of electrocuting to the human body.

3. When an abnormal breakpoint of the ground wire occurs in the circuit, the leakage current on the shell of the electric equipment can not discharge to the ground, so that the danger of electric shock is generated to a human body.

4. In a common household power supply system, a ground wire is only used for ground protection, the purpose of the ground wire is single, so that the ground wire can be protected by users, partial users even abandon the use of the ground wire, and only use a two-wire power supply system of a live wire and a zero wire, so that when metal shells of some electric equipment are electrified, a current loop can be released through a human body, and the probability of contact accidents is improved.

Disclosure of Invention

The invention aims to provide a novel three-wire dual-power-supply safety circuit system, in particular to a circuit system which additionally provides a low-voltage direct-current power supply by utilizing a ground zero wire and can effectively protect various abnormal or fault conditions in a power supply system.

In order to achieve the purpose, the invention adopts the following technical scheme: a novel three-wire system dual-power safety circuit system comprises a power module and an electric leakage protection module, wherein the power module comprises an AC-to-low voltage DC power supply conversion circuit and a rectifier bridge, an output live wire and an output zero line are connected to the input end of the AC-to-low voltage DC power supply conversion circuit, the output end of the AC-to-low voltage DC power supply conversion circuit outputs the positive pole of low voltage DC and the negative pole of low voltage DC through the rectifier bridge, the positive pole of the low voltage DC is connected with a ground wire input by mains supply through a first voltage dependent resistor and is output as a ground wire with the low voltage DC, and the negative pole of the low voltage DC is connected with the zero line input by the mains supply; the positive pole of the low-voltage direct current and the negative pole of the low-voltage direct current are connected with a first overcurrent breaker, and a live wire input by commercial power and a zero line input by commercial power pass through a second overcurrent breaker and then serve as an output live wire and an output zero line; the leakage protection module comprises a first piezoresistor, a first overcurrent breaker and a second overcurrent breaker.

Furthermore, the leakage protection module also comprises a negative charge release circuit, the negative charge release circuit is formed by connecting a resistor and a capacitor which are connected in parallel and then connecting a diode in series, and the negative charge release circuit is connected between the anode of the low-voltage direct current and a zero line input by commercial power.

Furthermore, the power module further comprises a negative charge leakage current detection circuit, the negative charge current detection circuit comprises a pulse square wave driver and an IGBT field effect tube, the output end of the alternating current-to-low voltage direct current power conversion circuit is connected to the pulse square wave driver and the output end of the alternating current-to-low voltage direct current power conversion circuit is connected to the control end of the IGBT field effect tube, and the IGBT field effect tube is connected in series with the output end of the rectifier bridge.

Furthermore, the leakage protection module further comprises a low-voltage direct current protection circuit, wherein the low-voltage direct current protection circuit comprises a first rectifier diode, a second rectifier diode, a current-limiting reactor and a current-discharging circuit, the first rectifier diode is connected to the negative pole of the low-voltage direct current, the second rectifier diode is connected to the positive pole of the low-voltage direct current, the first rectifier diode is used for allowing current to flow in from the negative pole of the low-voltage direct current, and the second rectifier diode is used for allowing current to flow out from the positive pole of the low-voltage direct current; the current limiting reactor is connected in series with the output end of the rectifier bridge; the bleeder circuit comprises a transient diode, a bleeder resistor and a light emitting diode which are connected in series, and is connected in parallel with the output end of the rectifier bridge.

Furthermore, the leakage protection module further comprises a second voltage dependent resistor, and the second voltage dependent resistor is connected between the positive pole of the low-voltage direct current and a zero line of the commercial power input.

Specifically, a third voltage dependent resistor is connected between the output zero line and a ground wire with low-voltage direct current.

Specifically, the third voltage dependent resistor is connected with the output zero line through an overload fuse.

The overload protection circuit comprises an overload detection circuit and a leakage current trigger circuit, wherein the detection end of the overload detection circuit is connected between an output live wire and a load, and the output end of the overload detection circuit is connected with a ground wire with low-voltage direct current through the leakage current trigger circuit; the leakage current trigger circuit is formed by connecting a capacitor and a resistor which are connected in parallel and then connecting a diode in series, and is used for releasing negative current on an output live wire.

Furthermore, an alarm circuit is arranged in the power module and comprises a storage battery, an electromagnetic relay, a control switch and an alarm device, the storage battery is connected to the output end of the alternating current-to-low voltage direct current power supply conversion circuit, the storage battery is connected with a normally closed switch terminal, the control switch and the alarm device of the electromagnetic relay in series to form a complete loop, and a coil of the electromagnetic relay is connected between an output live wire and an output zero line.

Further, the environment anomaly detection circuit comprises an environment detection sensor, a trigger switch and a leakage current release circuit, wherein the trigger output end of the environment detection sensor is connected to the control end of the trigger switch, and the trigger switch and the leakage current release circuit are connected in series and then connected between the output live wire and the ground wire with low-voltage direct current.

The invention has the beneficial effects that: the low-voltage direct-current circuit is additionally arranged, and the existing ground wire and the zero line are used as the output loop of the low-voltage direct-current power supply, so that double-power supply can be provided in a three-wire system household power supply system, an adaptive power supply does not need to be additionally added in various intelligent household appliances for an intelligent control module which needs low-voltage direct-current power supply in the intelligent household appliances, the function of the ground wire can be expanded, and the utilization rate of the ground wire is improved; meanwhile, a detection protection circuit for zero line open circuit virtual connection and partial line overload is added, and a circuit for detecting abnormal conditions (such as smoke generated by fire, gas leakage and the like) occurring in the surrounding environment and triggering alarm is added, so that the overall safety protection performance of the circuit system is effectively improved, and the convenience and the safety of household power utilization are ensured.

Drawings

FIG. 1 is a schematic circuit diagram of the circuit system as a whole in an embodiment;

FIG. 2 is a schematic diagram of a load connection circuit for overload protection of an individual line using an overload fuse in an embodiment;

fig. 3 is a schematic diagram of a load connection circuit for overload protection using an overload protection circuit in an embodiment.

Detailed Description

Embodiment 1, refer to fig. 1 to 3, a novel three-wire dual-power-supply safety circuit system includes a power module and a leakage protection module, where the power module includes an ac-to-low voltage dc power conversion circuit 11 and a rectifier bridge 12, an output live wire 24 and an output zero line 25 are connected to an input end of the ac-to-low voltage dc power conversion circuit 11, an output end of the ac-to-low voltage dc power conversion circuit 11 outputs a positive electrode 13 of low voltage dc and a negative electrode 14 of low voltage dc through the rectifier bridge 12, the positive electrode 13 of low voltage dc is connected to a ground wire 23 of a mains supply input through a first voltage dependent resistor 31 and is output as a ground wire 26 with low voltage dc, and the negative electrode 14 of low voltage dc is connected to the output zero line 25; the positive electrode 13 of the low-voltage direct current and the negative electrode 14 of the low-voltage direct current are connected with a first overcurrent breaker 41, and a live wire 21 input by mains supply and a zero wire 22 input by mains supply pass through a second overcurrent breaker 42 to serve as an output live wire 24 and an output zero wire 25; the first varistor 31, the first overcurrent breaker 41 and the second overcurrent breaker 42 constitute the above-mentioned earth leakage protection module.

In this embodiment, the outgoing live wire 24 and outgoing zero line 25 convert the 220V ac power into the low voltage dc power through the ac-to-low voltage dc power conversion circuit 11 and output the positive electrode 13 of the low voltage dc power and the negative electrode 14 of the low voltage dc power through the rectifier bridge 12, wherein the positive electrode 13 of the low voltage dc power is connected to the ground wire of the mains supply input through the first voltage dependent resistor 31 and output as the ground wire 26 with the low voltage dc power, and during normal power supply, the ground wire 26 with the low voltage dc power outputs the low voltage dc power outwards, and the negative electrode 14 of the low voltage dc power is connected to the outgoing zero line 25, so that a loop of the low voltage dc power is formed between the ground wire 26 with the low voltage dc power and the outgoing zero line 25, and the low voltage dc power can be output outwards, and at this time, the first voltage dependent resistor 31 connected between the ground wire 26 with the low voltage dc power and the ground wire 23 of the mains supply input is equivalent to a disconnected switch because it is not reached, when the earth wire 26 with low-voltage direct current has a higher voltage due to the occurrence of a leakage condition, the first voltage dependent resistor 31 is conducted to lead out leakage current from the earth wire 23 of the mains input, so that the earth wire 26 with low-voltage direct current has the functions of outputting low-voltage direct current and a common earth wire at the same time, wherein when the metal shell of the load is grounded, as shown in fig. 2 or fig. 3, because the first voltage dependent resistor is connected with the earth wire 26 with low-voltage direct current, in order to avoid the low voltage on the metal shell of the load, a voltage dependent resistor can be connected to the earth wire 26 with low-voltage direct current and then connected to the metal shell of the load, and the voltage dependent resistor is triggered to conduct to discharge only when the metal shell has a higher voltage. In addition, a first overcurrent breaker 41 is connected to the positive electrode 13 of the low-voltage direct current and the negative electrode 14 of the low-voltage direct current, and can be disconnected when the current in the low-voltage direct current loop output by the rectifier bridge 2 is too high, so that the rectifier bridge 2 and the alternating current to low-voltage direct current power conversion circuit 1 are protected. The second overcurrent breaker 42 connected to the live wire 21 and the neutral wire 22 is a commonly installed fuse, and when there is an electric leakage, a short circuit, an overcurrent, or an overload, the second overcurrent breaker 42 is triggered to open, thereby protecting the circuit system.

In a further embodiment, the earth leakage protection module further comprises a low-voltage direct current protection circuit 5, the low-voltage direct current protection circuit 5 comprises a first rectifying diode 51, a second rectifying diode 52, a current-limiting reactor 53 and a current-discharging circuit 54, the first rectifying diode 51 is connected to the negative pole of the low-voltage direct current, the second rectifying diode 52 is connected to the positive pole 13 of the low-voltage direct current, the first rectifying diode 51 allows current to flow from the negative pole 14 of the low-voltage direct current, and the second rectifying diode 52 allows current to flow from the positive pole 13 of the low-voltage direct current; the current limiting reactor 53 is connected in series with the output end of the rectifier bridge 2; the bleeder circuit 54 comprises a transient diode, a bleeder resistor and a light emitting diode connected in series, and the bleeder circuit 54 is connected in parallel to the output terminal of the rectifier bridge 2. The low-voltage dc protection circuit 5 is used for protecting the low-voltage dc output from the rectifier bridge 12 and the load connected to the rectifier bridge, wherein the first rectifier diode 51 and the second rectifier diode 52 can limit the direction of the current flowing through the rectifier bridge 12, so as to prevent the rectifier bridge 12 from being damaged by the reverse high voltage or large current, when the positive electrode 13 of the low-voltage dc is positively charged, the current can be released through the ground wire 23 of the commercial power input, and when the positive electrode 13 of the low-voltage dc is negatively charged, the current can be released through the ground wire 23 of the commercial power input simultaneously through the second rectifier diode 52, the rectifier bridge 12, the current limiting reactor 53, the first rectifier diode 51 and the zero line 22 of the commercial power input, wherein the current limiting reactor 53 can limit the flowing current, so as to prevent the rectifier bridge 12 from being damaged by the excessive current, and at the same time, the current leakage circuit 54 can perform auxiliary current leakage to the rectifier bridge 12, the voltage at the output of the rectifier bridge 12 can be effectively stabilized.

In a further embodiment, the earth leakage protection module further comprises a negative charge release circuit 6, the negative charge release circuit 6 is formed by connecting a resistor and a capacitor in parallel and then connecting a diode in series, and the negative charge release circuit 6 is connected between the positive electrode 13 of the low-voltage direct current and the zero line 22 of the commercial power input. When the ground wire 23 of the commercial power input has a break point and cannot form a discharge loop, the negative charge release circuit 6 can guide the negative charge on the ground wire 26 with low-voltage direct current to the zero line 22 of the commercial power input, so as to form leakage current to trigger the second overcurrent breaker 42 to be disconnected for protection. The diode capacity current on the negative charge releasing circuit 6 flows from the zero line 22 of the commercial power input to the ground wire 26 with the low-voltage direct current, so that the negative charge on the ground wire 26 with the low-voltage direct current can be released, and when the circuit system normally operates, the ground wire 26 with the low-voltage direct current and the zero line 22 of the commercial power input cannot be conducted. The power module further comprises a negative charge leakage current detection circuit 7, the negative charge current detection circuit 7 comprises a pulse square wave driver 71 and an IGBT field effect tube 72, an output end of the alternating current-to-low voltage direct current power conversion circuit 11 is connected to the pulse square wave driver 71 and outputs to a control end of the IGBT field effect tube 72, and the IGBT field effect tube 72 is connected in series with an output end of the rectifier bridge 12. The pulse square wave driver 71 is used for emitting square wave signals with certain frequency and certain duty ratio to control the conduction of the IGBT field effect tube 72, preferably, the pulse square wave driver 71 emits square wave signals with the duty ratio of 99% and the frequency of more than 90Hz, at the moment, 1% of open circuit gaps exist in the IGBT field effect tube 72, the negative charge releasing circuit 6 can detect whether negative charges exist in the positive electrode 13 of the low-voltage direct current by utilizing the 1% of open circuit gaps in the IGBT field effect tube 72, when the positive electrode 13 of the low-voltage direct current has negative charges, the negative charge releasing circuit 6 can rapidly release the negative charges carried by the positive electrode 13 of the low-voltage direct current by utilizing the 1% of open circuit gaps in the IGBT field effect tube 72, and meanwhile, the second overcurrent breaker 42 can be triggered to be switched off to realize the protection of a circuit system. It should be noted that, because the IGBT fet 72 has a 1% open gap, and its on-off frequency is higher than 90Hz, the 1% open gap time is also very short, and its influence on the connected low-voltage dc load is negligible, and at the same time, an inductor and a capacitor may also be connected to the load, thereby eliminating the influence of the open gap.

In a further embodiment, the earth leakage protection module further comprises a second voltage dependent resistor 32, and the second voltage dependent resistor 32 is connected between the positive electrode 13 of the low voltage direct current and the neutral line 22 of the mains input. The second voltage dependent resistor 32 can release the leakage current existing on the ground wire 26 with low-voltage direct current together with the ground wire 23 with commercial power input, so as to construct ground wire zero line double-wire leakage protection, which can improve the speed of releasing the leakage current on one hand, and can still release the leakage current by using the zero line 22 with commercial power input when the ground wire 23 with commercial power input has a breakpoint on the other hand. The safety of the circuit system is effectively improved.

Specifically, a third voltage dependent resistor 33 is connected between the tail end of the output zero line 25 and the ground wire 26 with low-voltage direct current; as shown in fig. 1, 2 or 3, in the circuit connected to the load, when a break point occurs on the output zero line 25, the break point cannot form a complete loop, and by arranging the third piezoresistor 33 between the end of the output zero line 25 and the ground line 26 with low-voltage direct current, the current on the output live wire 24 can form a loop through the third piezoresistor 33, the ground line 26 with low-voltage direct current, the first piezoresistor 31 and the ground line 23 with commercial power input after passing through the load, thereby generating leakage current to trigger the second overcurrent breaker 42 to be disconnected, and playing a role in protecting a circuit system.

Referring to fig. 2, an overload fuse 81 is further connected to the output zero line 25, and the overload fuse 81 can be triggered to be disconnected when the load of the line is too large, so as to trigger the third voltage dependent resistor 33 to generate leakage current, so that the second overcurrent breaker 42 is disconnected, and thus the problem of fire hazard caused by the fact that the second overcurrent breaker 42 is not triggered due to too high load in part of low-load lines is avoided. The overload fuse 81 is preferably an automatically recoverable fuse.

In addition, referring to fig. 3, a separate overload protection circuit 8 may also be provided, where the overload protection circuit 8 includes an overload detection circuit 82 and a leakage current trigger circuit 83, a detection end of the overload detection circuit 82 is connected between the output live wire 24 and the load, and an output end of the overload detection circuit 82 is connected to the ground wire 26 with low-voltage direct current through the leakage current trigger circuit 83; the leakage current trigger circuit 83 is formed by a capacitor and a resistor connected in parallel and then connected in series with a diode, and the leakage current trigger circuit 83 is used for releasing the negative current on the output live wire 24. When the line is overloaded, the three-terminal thermal fuse 82 generates too much heat, so that the internal thermal metal sheet is deformed and conducted with the leakage current trigger circuit 83, and then leakage current is formed through the leakage current trigger circuit 83 and the ground wire 26 with low-voltage direct current, so that the second overcurrent breaker 42 is triggered to be disconnected to protect the circuit system.

In a further embodiment, an alarm circuit 9 is arranged in the power module, the alarm circuit 9 includes a storage battery 91, an electromagnetic relay 92, a control switch 93 and an alarm device 94, the storage battery 91 is connected to the output end of the ac to low voltage dc power conversion circuit 11, the storage 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 loop, and the coil of the electromagnetic relay 92 is connected between the output live wire 24 and the output neutral wire 25. Whether the second overcurrent breaker 42 is disconnected or not can be detected by the electromagnetic relay 92 connected between the output live wire 24 and the output zero wire 25 through a coil, and when the second overcurrent breaker 42 is disconnected, the coil of the electromagnetic relay 92 is powered off, so that the normally closed switch terminal of the electromagnetic relay 92 connected in series in the alarm circuit 9 is closed, the alarm circuit 92 is switched on, the alarm device 94 sends out an alarm signal, and related personnel are reminded of overhauling a circuit system. The storage battery 91 can supply power to the alarm circuit 9, the alarm device 94 can adopt a buzzer, a warning lamp or other related alarm devices which can play a warning role, and the control switch 93 can disconnect the alarm circuit 9 to stop alarming after a maintainer arrives at a site.

In a further embodiment, the environmental anomaly detection circuit 10 is further included, the environmental anomaly detection circuit 10 includes an environmental detection sensor 101, a trigger switch 102 and a leakage current release circuit 103, a trigger output end of the environmental detection sensor 101 is connected to a control end of the trigger switch 102, and the trigger switch 102 and the leakage current release circuit 103 are connected in series and then connected between the output live wire 24 and the ground wire 26 with low-voltage direct current. The environment anomaly detection circuit 10 can detect the anomaly of the surrounding environment and trigger the leakage current to disconnect the second overcurrent breaker 42 after the anomaly occurs, and further trigger the alarm circuit 9 to be switched on to send out an alarm signal. The environment detecting sensor 101 may be selected according to the environmental abnormal condition to be detected, including but not limited to smoke sensor, gas sensor, temperature sensor, etc. When the ambient environment is abnormal, the trigger output end of the environment detection sensor 101 sends a signal to the control end of the trigger switch 102, so that the trigger switch 102 is turned on, the leakage current release circuit 103 forms a loop with the output live wire 24 and the ground wire 26 with low-voltage direct current, and releases the leakage current, thereby triggering the second overcurrent breaker 42 to open. The trigger switch 102 may be a thyristor.

It should be understood that the above-mentioned embodiments are merely preferred embodiments of the present invention, and not intended to limit the scope of the invention, therefore, all equivalent changes in the principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a novel two power supply safety circuit system of three-wire system which characterized in that: the low-voltage direct-current power supply conversion circuit comprises a power supply module and an electric leakage protection module, wherein the power supply module comprises an alternating current to low-voltage direct-current power supply conversion circuit and a rectifier bridge, an output live wire and an output zero line are connected to the input end of the alternating current to low-voltage direct-current power supply conversion circuit, the output end of the alternating current to low-voltage direct-current power supply conversion circuit outputs a positive pole of low-voltage direct current and a negative pole of the low-voltage direct current through the rectifier bridge, the positive pole of the low-voltage direct current is connected with a ground wire input by mains supply through a first voltage dependent resistor and is output as a ground wire with the low-voltage direct current, and the negative pole of the low-voltage direct current is connected with the zero line input by the mains supply; the positive pole of the low-voltage direct current and the negative pole of the low-voltage direct current are connected with a first overcurrent breaker, and a live wire input by commercial power and a zero line input by commercial power pass through a second overcurrent breaker and then serve as an output live wire and an output zero line; the leakage protection module comprises a first piezoresistor, a first overcurrent breaker and a second overcurrent breaker.

2. The novel three-wire system dual-power safety circuit system of claim 1, characterized in that: the leakage protection module further comprises a negative charge release circuit, the negative charge release circuit is formed by connecting a resistor and a capacitor which are connected in parallel and then connecting a diode in series, and the negative charge release circuit is connected between the positive pole of the low-voltage direct current and a zero line of the mains supply input.

3. The novel three-wire system dual-power safety circuit system of claim 2, wherein: the power module further comprises a negative charge leakage current detection circuit, the negative charge current detection circuit comprises a pulse square wave driver and an IGBT field effect tube, the output end of the alternating current-to-low voltage direct current power conversion circuit is connected to the pulse square wave driver and the control end of the IGBT field effect tube in output connection, and the IGBT field effect tube is connected in series with the output end of the rectifier bridge.

4. The novel three-wire system dual-power safety circuit system according to claim 1, characterized in that: the leakage protection module further comprises a low-voltage direct current protection circuit, the low-voltage direct current protection circuit comprises a first rectifier diode, a second rectifier diode, a current-limiting reactor and a current-discharging circuit, the first rectifier diode is connected to the negative pole of the low-voltage direct current, the second rectifier diode is connected to the positive pole of the low-voltage direct current, the first rectifier diode is used for allowing current to flow in from the negative pole of the low-voltage direct current, and the second rectifier diode is used for allowing current to flow out from the positive pole of the low-voltage direct current; the current limiting reactor is connected in series with the output end of the rectifier bridge; the bleeder circuit comprises a transient diode, a bleeder resistor and a light emitting diode which are connected in series, and is connected in parallel with the output end of the rectifier bridge.

5. The novel three-wire system dual-power safety circuit system of claim 1, characterized in that: the leakage protection module further comprises a second voltage dependent resistor, and the second voltage dependent resistor is connected between the positive pole of the low-voltage direct current and a zero line input by commercial power.

6. The novel three-wire system dual-power safety circuit system of claim 1, characterized in that: and a third voltage dependent resistor is connected between the output zero line and a ground wire with low-voltage direct current.

7. The novel three-wire system dual-power safety circuit system of claim 6, wherein: and the third piezoresistor is connected with the output zero line through an overload fuse.

8. The novel three-wire system dual-power safety circuit system of claim 1, characterized in that: the overload protection circuit comprises an overload detection circuit and a leakage current trigger circuit, wherein the detection end of the overload detection circuit is connected between an output live wire and a load, and the output end of the overload detection circuit is connected with a ground wire with low-voltage direct current through the leakage current trigger circuit; the leakage current trigger circuit is formed by connecting a capacitor and a resistor which are connected in parallel and then connecting a diode in series, and is used for releasing negative current on an output live wire.

9. A novel three-wire dual-power safety circuit system according to any one of claims 1-8, characterized in that: the power module is internally provided with an alarm circuit which comprises a storage battery, an electromagnetic relay, a control switch and an alarm device, wherein the storage battery is connected to the output end of the AC-to-low voltage DC power supply conversion circuit, the storage battery is connected in series with a normally closed switch terminal, the control switch and the alarm device of the electromagnetic relay to form a complete loop, and a coil of the electromagnetic relay is connected between an output live wire and an output zero line.

10. The novel three-wire system dual-power safety circuit system of claim 9, wherein: the environment anomaly detection circuit comprises an environment detection sensor, a trigger switch and a leakage current release circuit, wherein the trigger output end of the environment detection sensor is connected to the control end of the trigger switch, and the trigger switch and the leakage current release circuit are connected in series and then connected between the output live wire and the ground wire with low-voltage direct current.