CN217115603U

CN217115603U - Automatic sensing and electric leakage detection protection circuit

Info

Publication number: CN217115603U
Application number: CN202120471742.8U
Authority: CN
Inventors: 孙茹
Original assignee: Yinhezhixing Chengdu New Energy Co ltd
Current assignee: Yinhezhixing Chengdu New Energy Co ltd
Priority date: 2021-03-04
Filing date: 2021-03-04
Publication date: 2022-08-02
Anticipated expiration: 2031-03-04

Abstract

The principle of the automatic sensing and electric leakage detection protection circuit is that an induction coil is adopted to detect induction voltage generated by an electromagnetic field around a live wire and transmit the induction voltage into the live wire of an electric appliance, if the induction voltage can be detected at a zero line end of the electric appliance, an electric appliance switch is in a switch-on state, a controller (MCU) can send a signal for switching on a circuit to drive a relay to supply power to the electric appliance, otherwise, the controller (MCU) can send a signal for switching off the relay circuit to cut off the power supply of the electric appliance; the induction coil is adopted to detect the magnetic field intensity around the ground wire, the conditions of disconnection of the ground wire, electrification of the ground wire (or an electric appliance shell) and electrification of a water body are judged, the controller (MCU) can send a signal for disconnecting a relay circuit, the power supply of an electric appliance is cut off, and alarm information is sent.

Description

Automatic sensing and electric leakage detection protection circuit

Technical Field

The invention relates to the field of safety protection, in particular to a sensing power supply and electric leakage detection protection circuit.

Background

Electric power is the basis of modern civilization, hundreds of millions of electric appliances are produced every year around the world, and the electrical safety is the most basic requirement, and the correct connection of power cords is crucial to the safety of electric appliances and people. However, due to wrong wiring, aging of the electric appliance, moisture, water and the like, objects which should not be electrified originally may be electrified, and people are very likely to get an electric shock. Although many buildings are provided with earth leakage protectors at present, many people die each year due to electric shock, and the root causes are as follows.

1. The live wire and the zero wire are reversely connected, and the inside of the electric appliance is still electrified after the electric appliance stops working, so that electric leakage or electric shock accidents can still be caused.

2. The circuit aging, the component breakdown and the circuit water lead to the accidental electrification of the ground wire and the zero line, and the electric shock accident is very easy to cause.

3. The tripping current of the current leakage protector is generally 20-30Ma, which is larger than the safety current (10mA) of human body.

4. Earth leakage protectors all rely on correct wiring and once wiring is problematic, earth leakage protection can fail.

5. The leakage protector needs to be pressed once a month, and in fact, people rarely press once a month, and even if the leakage protector fails, the leakage protector cannot know the fact.

6. The leakage protector belongs to a post intervention type, namely, the leakage protector can be tripped after leakage current is formed or a person gets an electric shock.

7. The leakage protector is designed according to electric shock in a dry environment, but when a human body is in a wet or underwater state, the safety voltage of the human body can be reduced to 12V, the safety current can be reduced, and electric shock accidents are easy to happen.

Therefore, the circuit can automatically cut off the power supply when the electric appliance stops working, can detect whether the zero line, the ground wire, the electric appliance shell and the water body are electrified or not in real time, can eliminate hidden dangers before electric shock accidents occur, and is more convenient and safer than the existing leakage protector.

Although some leakage protection circuit inventions exist at present, the leakage protection circuit inventions have the following three serious defects.

1. It is common to use the ground of the power supply as a zero voltage reference point, and the protection function fails when there is no ground or the ground is accidentally disconnected. For example, patent application No. 201310731745.0, which is based on the ground wire as a reference point, the whole circuit will fail completely once the ground wire is not connected or disconnected. For another example, according to the invention with application number 201310192009.2, the piezoresistor RV1 or RV2 is connected between the live wire and the ground wire, when the piezoresistor breaks down, the ground wire is easily charged abnormally, and actually, the piezoresistor still has leakage current, although the leakage current of a single piezoresistor is less than 20 milliamperes, if the whole building has many such devices, the leakage current flowing into the ground wire from the live wire is very large, the total leakage protector of the power distribution cabinet can trip continuously, and serious power failure accidents are caused, and this type of patent has no practical value at all.

2. The power ground wire is used as a zero voltage reference point, and when the detection object is a live wire, if an element connected between the live wire and the ground wire is broken down, the ground wire is electrified, so that the shell of the electric appliance is electrified, and the personal safety can be greatly threatened. For example, a large number of related patents such as the patent with the authorization number of CN 107703414B from Hua corporation, the patent with the authorization number of CN 109256763B from Glare corporation, and the patent with the publication number of CN 109581141A from Haier corporation all have the same potential safety hazard.

3. Some inventions use the zero line of the power supply as a zero voltage reference point, but if the live wire and the zero line are reversely connected, the zero line and the ground wire are reversely connected, or the zero line voltage is increased due to unbalanced three-phase load, the leakage detection circuit is invalid or inaccurate, and the zero line voltage may be more harmful to users.

The invention provides a safer electric leakage detection method aiming at the serious defects of the current electric leakage detection technology.

Disclosure of Invention

The invention aims to provide a circuit and an application method, wherein the circuit can automatically sense the power utilization state of an electric appliance, automatically supply and cut off power along with the shutdown-startup of power utilization equipment, and simultaneously can detect the reverse connection of a live wire and a zero line, the disconnection of a ground wire, the electrification of the ground wire and the electrification of a water body.

According to the principle of the invention, the automatic sensing and electric leakage detection protection circuit is characterized by comprising a control circuit, a detection circuit, an amplification circuit, a low-voltage direct-current power supply and an alarm circuit; wherein a pair of duplex normally open contacts of the relay in the control circuit is connected in series in the live wire and the zero line between the power supply and the electrical appliance, the coil of the relay, the emitter and the collector of the triode are connected in series and then connected with the anode and the cathode of the power circuit, and the base of the triode is connected in series with the base resistor and then connected with the output channel (DO) of the MCU in the control circuit; the detection circuit comprises a live wire detection coil, a zero line detection coil and a ground wire detection coil; the live wire detection coil is wound at a normally charged end (input end) of the live wire and relay contact, one end of the coil is suspended, and the other end of the coil is connected to the live wire output contact of the relay; the zero line detection coil is wound on a zero line output wire of the relay contact, one end of the zero line detection coil is suspended, and the other end of the zero line detection coil is connected with the input end of the amplifying circuit after being connected with a resistor in series; the ground wire detection coil is wound at the wire connecting end of an electric appliance (or a socket), one end of the ground wire detection coil is connected with the input end of the amplifying circuit after being connected with a resistor in series, and the other end of the ground wire detection coil is suspended in the air or connected to a detection electrode in a water body; the amplifying circuit is a small signal amplifier, and the output end of the amplifying circuit is connected with the input port of the MCU of the control circuit.

Preferably, the low-voltage direct-current power supply is one of an isolated low-voltage direct-current power supply, a dry battery and a storage battery.

Preferably, the alarm circuit has the functions of light and sound alarm, sound prompt is provided when the relay is switched on and switched off, and the relay is switched off or switched on after 2-10 seconds of delay.

Preferably, the detection electrode placed in the water body is in a ring shape or a barrel shape, and surrounds the electric wire of the possible electric leakage point.

Drawings

Fig. 1 is a schematic diagram of the circuit of the present invention.

Fig. 2 is a schematic view of the present invention applied to a socket.

Detailed Description

An example of an auto-sensing and leakage detection protection circuit in accordance with the principles of the present invention is as follows.

Example 1.

An automatic sensing and leakage detection protection circuit is shown in fig. 1, wherein a low-voltage direct-current power supply comprises an isolation transformer T1, a capacitor C1 and a voltage regulator tube Z1 and is used for providing power for a control circuit, a detection circuit, an amplification circuit, an alarm circuit and the like. The control circuit comprises a triode Q1, a relay KM1, a resistor RQ structure, a control chip U1 and a coupling capacitor C2, wherein a pair of normally open contacts of the relay KM1 are connected in series in a live wire and a zero wire, a coil of the relay KM1 is connected with an emitter and a collector of the triode Q1 in series and then connected to the positive end and the negative end of a power supply, and the resistor RQ is connected between a base of the triode Q1 and an output end (DO) of the control chip U1. The working indicator light LED, the language chip U2 and the loudspeaker SPK form an alarm circuit which is respectively connected with the output port of the control circuit chip U1. The live wire detection coil L1 is wound at the input end of the live wire L, one end of the coil L1 is connected to a point A on the normally open contact live wire output end of the relay KA1, the other end of the coil L1 is suspended, and the coil L1 is insulated from the live wire L. The ground wire detection coil L3 is wound on the power ground wire, one end of the coil L3 is connected to the resistor RE, the other end of the resistor RE is connected to the input end of the amplifying circuit AE, the output end of the amplifying circuit AE is connected to the input end of the chip U1(MCU) of the control circuit, and the other end of the coil L3 is suspended (or connected to the general detection electrode of the water body to detect that the water body is electrified). A zero line detection coil L2 is wound on the side of a point B of a zero line output end of a normally open contact of a relay KA1, one end of a coil L2 is connected to a resistor RN, the other end of the resistor RN is connected to the input end of a signal amplification circuit AN, and the output end of AN amplifier AN is connected to the input end of a chip U1(MCU) of a control circuit. The amplifier circuits AE and AN are both amplifier circuits composed of small-signal amplifiers, as indicated by the circuit in the dashed line frame of AE.

In fig. 1, a dotted line frame where a resistor RL and a switch SL are located represents AN electric device, P1 represents a socket (or no socket), when the electric device switch SL is closed, AN alternating voltage induced by a live line detection coil L1 is transmitted to a point B through RL, so that a voltage is generated on a neutral line detection coil L2, the voltage is amplified by AN amplifying circuit AN and enters a U1(MCU) of a control circuit, after internal program processing, a high voltage is output at a base of a triode Q1, a relay KA1 coil is electrified, a normally closed contact KA1 of a main circuit in series with the relay KA1 is closed, and the electric device RL starts to operate normally. When the switch SL of the electric equipment RL is disconnected, the induced voltage on the zero line detection coil L2 disappears, and the chip U1 in the control circuit detects that the induced voltage on the coil L2 disappears, and sends low voltage to the base electrode of the triode Q1, so that the relay KA1 is disconnected, and the power supply of the electric equipment is cut off. When the ground of the power supply ground wire E is disconnected, voltage is induced on the ground wire due to the fact that the live wire and the ground wire are close to each other and parallel, so that voltage is generated on a ground wire detection coil L3, then the voltage is input into a chip U1 of a control circuit through a resistor RE and an amplifying circuit AE, and the power supply is cut off or alarm information is output at the alarm circuit language chip U2 and a loudspeaker SPK immediately after judgment through a built-in program.

If the live wire-zero line of the power input line is reversely connected, as in the case of the right-most live wire L and zero line N in the figure 1, the live wire detection coil L1 has no induced voltage, even if the switch SL is closed, no induced voltage exists in the coil L2, the relay KA1 is not closed, the electric equipment RL in the main circuit is not electrified, and the circuit is not externally supplied with power under the condition of reverse connection of the zero line-live wire.

As shown in FIG. 2, the circuit is placed inside the socket, the detecting electrode ring 2 is connected with the point C of the ground wire detecting coil by a lead, when the detecting electrode ring 2 in the socket panel is electrified, the voltage enters the control circuit chip U1 through the resistor RE and the amplifying circuit AE, and the main power supply is cut off or alarm information is given under the control of the program inside the chip U1.

The foregoing has described the general principles, principal features, and advantages of the invention. It is to be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and the above-described embodiments and descriptions are only illustrative of one application of the principles of the present invention, and that changes in the component structure, type, number, shape, material, installation, size, installation and other parameters may be made without departing from the principles of the present invention, and such changes and modifications are intended to be within the scope of the present invention.

Claims

1. The automatic sensing and electric leakage detection protection circuit is characterized by comprising a control circuit, a detection circuit, an amplification circuit, a low-voltage direct-current power supply and an alarm circuit; the base of the triode is connected with the output channel of the MCU in the control circuit after being connected with the base resistor in series; the detection circuit comprises a live wire detection coil, a zero line detection coil and a ground wire detection coil; the live wire detection coil is wound at the normally charged end of the live wire and relay contact, one end of the coil is suspended, and the other end of the coil is connected to the live wire output contact of the relay; the zero line detection coil is wound on a zero line output wire of the relay contact, one end of the zero line detection coil is suspended, and the other end of the zero line detection coil is connected with the input end of the amplifying circuit after being connected with a resistor in series; the ground wire detection coil is wound at the power connection end of the electric appliance, one end of the ground wire detection coil is connected with the input end of the amplifying circuit after being connected with the resistor in series, and the other end of the ground wire detection coil is suspended in the air or connected to a detection electrode in a water body; the amplifying circuit is a small signal amplifier, and the output end of the amplifying circuit is connected with the input port of the MCU of the control circuit.

2. The automatic sensing and leakage detection protection circuit of claim 1, wherein the low voltage dc power supply is one of an isolated low voltage dc power supply, a dry cell, and a battery.

3. The automatic sensing and leakage detection circuit as claimed in claim 1, wherein the alarm circuit has a light and sound alarm function, and has a sound alarm when the relay is turned on or off, and the relay is turned off or on after a delay of 2-10 seconds.

4. The automatic sensing and earth leakage detection protection circuit of claim 1, wherein the detection electrode placed in the water body is ring-shaped or barrel-shaped and surrounds the wire at the potential point of electric leakage.