CN109787044B - Semi-intelligent three-pole on-off leakage protection plug - Google Patents

Abstract

The invention relates to a semi-intelligent tripolar on-off leakage protection plug, which comprises a direct current voltage stabilizing circuit, a relay switch circuit, a leakage protection circuit and a singlechip control circuit; the relay switch circuit comprises a relay with three groups of normally open contacts and a driving switch circuit, and the three groups of normally open contacts of the relay are respectively connected in series with a live wire L, a zero wire N and a ground wire E; the leakage protection circuit is characterized by further comprising an overvoltage protection circuit, an overtemperature protection circuit and a reset circuit, wherein the reset switch circuit resets the leakage protection circuit when power is off. The advantages are that: under the reset working condition, if the electric leakage fault occurs and meanwhile single-phase power failure occurs, if the socket with the switch is used, the live wire, the zero line and the grounded tripolar power supply can be cut off immediately, after the circuit is powered back, the original reset working condition can be automatically recovered as long as the electric leakage fault does not exist, the requirements of national standard low-voltage AC50V working can be met, the overvoltage and overtemperature protection function is also realized, the power consumption is low, the temperature rise is low, the anti-interference capability is strong, the circuit is simple, and the use is more convenient and safer.

Description

Semi-intelligent three-pole on-off leakage protection plug

Technical field

The invention relates to a semi-intelligent three-pole on-off leakage protection plug.

Background technique

Commonly used leakage protection plugs (PRCD) generally use mechanical tripping devices and monitoring circuits to control the three-pole power on and off of the neutral line N, live wire L and ground E. Because they are all residual current action tripping devices, they are used in When a leakage fault occurs, if there is no electric shock current, the leakage protection will not trip and cut off the power. Therefore, once a leakage fault occurs and a single-phase power outage occurs before tripping and the power is off, such as using a switch socket, the leakage protection will The control circuit will not trip due to the loss of working power, that is, the three-pole power supply cannot be cut off, so there is still a certain safety hazard; currently, there is a method that in the reset working state, once a leakage fault occurs, and encounters another In the case of a single-phase power outage or the use of a switch socket, the leakage protection plug of the power supply can be cut off, but it cannot meet the national standard requirements for low-voltage AC50V operation. There are also excessive static power consumption, temperature rise, poor anti-interference ability, and Defects such as complex circuitry.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a safer semi-intelligent three-pole on-off leakage protection plug. When the leakage protection is in the reset working state, if a leakage fault occurs or a single-phase power outage occurs, With a switch socket, etc., the three-pole power supply of live wire, neutral wire and ground can be cut off. After the circuit is restored to power, as long as there is no leakage fault, it will automatically return to the original reset working state, which can meet the requirements of low voltage AC50V operation. It meets the national standard requirements, and also has overvoltage and overtemperature protection functions, simple circuit, and strong anti-interference ability.

In order to achieve the above object, the present invention is implemented as follows. It is a semi-intelligent three-pole on-off leakage protection plug, including a DC voltage stabilizing circuit, a relay switch circuit, a leakage protection circuit and a single-chip microcomputer control circuit; the DC voltage stabilizing circuit The input end is electrically connected to the city AC power, and the output end of the DC voltage stabilizing circuit provides working power for the relay switching circuit, leakage protection circuit and microcontroller control circuit; the relay switching circuit includes a relay with three sets of normally open contacts and a drive switch circuit, one end of the relay is electrically connected to an output end of the DC voltage stabilizing circuit to obtain DC operating power, the other end of the relay is electrically connected to the output end of the drive switch circuit, and the three sets of normally open contacts of the relay are connected in series on the live wire. On L, neutral line N and ground line E, the input end of the driving switch circuit is electrically connected to the first output end of the single-chip microcomputer control circuit; the output end of the leakage protection circuit is electrically connected to the first input end of the single-chip microcomputer control circuit. ; It is characterized in that it also includes an overvoltage protection circuit, an overtemperature protection circuit and a reset circuit; the input end of the overvoltage protection circuit is electrically connected to the rectifier output end of the DC voltage stabilizing circuit, and the output end of the overvoltage protection circuit is controlled by the microcontroller The second input end of the circuit is electrically connected; one end of the over-temperature protection circuit is electrically connected to the neutral line N, and the other end of the over-temperature protection circuit is electrically connected to the third input end of the microcontroller control circuit; the input end of the reset circuit It is electrically connected to the output terminal of the driving switch circuit, and the output terminal of the reset circuit is electrically connected to the power circuit terminal of the leakage protection circuit. When the power is cut off, the reset circuit resets the leakage protection circuit.

In this technical solution, the reset circuit includes a second switching transistor, a seventh resistor, an eighth resistor and a fourth capacitor; one end of the eighth resistor and the fourth capacitor are connected in parallel with the base of the second switching transistor and the seventh capacitor respectively. One end of the resistor is electrically connected and the other end is grounded. The other end of the seventh resistor is electrically connected to the output end of the driving switching circuit. The emitter of the second switching transistor is grounded. The collector of the second switching transistor is electrically connected to the power circuit end of the leakage protection circuit. connect.

In this technical solution, the microcontroller control circuit includes a microcontroller and a reset switch; the model of the microcontroller is XJLB8002, with a total of 8 pins. Pin 1 of the microcontroller is connected to the neutral line N, and pin 2 of the microcontroller is the first output terminal. Pin 3 of the microcontroller is the first input terminal, pin 6 of the microcontroller is the second input terminal, pin 5 of the microcontroller is the third input terminal, pin 8 of the microcontroller is electrically connected to the positive output terminal of the DC voltage regulator circuit, and one end of the reset switch It is electrically connected to pin 4 of the microcontroller, and the other end of the reset switch is grounded; it also includes a work indication circuit. The work indication circuit includes a fourth resistor and a light-emitting diode. The fourth resistor is connected in series with the light-emitting diode and one end is electrically connected to pin 7 of the microcontroller. , the other end is electrically connected to an output end of the DC voltage stabilizing circuit.

In this technical solution, the DC voltage stabilizing circuit includes a rectifier diode, a first three-terminal voltage stabilizing block, a second three-terminal voltage stabilizing block, first to third electrolytic capacitors, a third capacitor and a sixth resistor; The anode of the rectifier diode is electrically connected to the live wire L, and the cathode of the rectifier diode is electrically connected to the positive terminal of the first electrolytic capacitor, the input terminal of the first three-terminal voltage stabilizing block and the input terminal of the overvoltage protection circuit respectively. The cathode of the rectifier diode is The rectifier output terminal of the DC voltage stabilizing circuit and the output terminal of the first three-terminal voltage stabilizing block are electrically connected to the positive terminal of the third electrolytic capacitor, one end of the sixth resistor, the input terminal of the second three-terminal voltage stabilizing block and one end of the relay respectively. connection, the first three-terminal voltage stabilizing block provides working voltage for the relay, and the other end of the sixth resistor provides DC working power for the leakage protection circuit; the negative terminal of the first electrolytic capacitor, the negative terminal of the third electrolytic capacitor and the first three terminal The ground terminals of the voltage stabilizing block are electrically connected to the neutral line N. The output terminals of the second three-terminal voltage stabilizing block are respectively connected to pin 8 of the microcontroller, the anode of the light-emitting diode, one end of the third capacitor and the positive terminal of the second electrolytic capacitor. Connect, the other end of the third capacitor, the negative end of the second electrolytic capacitor and the ground end of the second three-terminal voltage stabilizing block are all grounded.

In this technical solution, the overvoltage protection circuit includes a first resistor, a second resistor, a first capacitor and a voltage stabilizing diode; one end of the first resistor is electrically connected to the rectifier output terminal of the DC voltage stabilizing circuit, and the first resistor The other end is electrically connected to one end of the first capacitor and the cathode of the Zener diode. The other end of the first capacitor is electrically connected to the neutral line N. The anode of the Zener diode is electrically connected to one end of the second resistor and pin 6 of the microcontroller. The other end of the second resistor is connected to ground.

In this technical solution, the over-temperature protection circuit includes a second capacitor, a third resistor and a negative temperature coefficient thermistor; one end of the second capacitor, the third resistor and the negative temperature coefficient thermistor is connected in parallel to the neutral line N. Connect, and the other end is electrically connected to pin 5 of the microcontroller.

In this technical solution, a second diode is also included. Both ends of the second diode are connected in parallel to both ends of the relay. The cathode of the second diode is connected to the output end of the first three-terminal voltage stabilizing block. Electrical connection; the driving switch circuit includes a first switching transistor and a fifth resistor. The base of the first switching transistor is electrically connected to pin 2 of the microcontroller through the fifth resistor. The collector of the first switching transistor is connected to the other terminal of the relay. One end is electrically connected, the collector of the first switching transistor is also electrically connected to the second switching transistor through a seventh resistor, and the emitter of the first switching transistor is grounded.

The advantages of the present invention compared with the prior art are: in the reset working state, if a leakage fault occurs and a single-phase power outage occurs, such as using a switch socket, the three-pole power supply of live wire, neutral wire and grounding can be cut off immediately. , after the circuit is restored to power, as long as there is no leakage fault, it will automatically return to the original reset working state. It can not only meet the national standard low voltage AC50V working requirements, but also has overvoltage and overtemperature protection functions, and has low power consumption and low temperature rise. Low, strong anti-interference ability, simple circuit, more convenient and safer to use.

Description of the drawings

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

Implementation

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

In the description of the present invention, the terms "first" to "tenth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

As shown in Figure 1, it is a semi-intelligent three-pole on-off leakage protection plug, including DC voltage stabilizing circuit 1, relay switch circuit 2, leakage protection circuit 3, overvoltage protection circuit 4, overtemperature protection circuit 5, working Indicating circuit 6, microcontroller control circuit 7 and reset circuit 8; wherein, the input end of the DC voltage stabilizing circuit 1 is electrically connected to the city alternating current, and the output end of the DC voltage stabilizing circuit 1 is a relay switching circuit 2, a leakage protection circuit 3, Overvoltage protection circuit 4, overtemperature protection circuit 5, work indication circuit 6, microcontroller control circuit 7 and reset circuit 8 provide working power; the relay switch circuit 2 includes a relay JK with three sets of normally open contacts and a drive switch circuit , one end of the relay JK is electrically connected to an output end of the DC voltage stabilizing circuit 1 to obtain DC working power, the other end of the relay JK is electrically connected to the output end of the drive switch circuit, and the three sets of normally open contacts of the relay JK are respectively Connected in series on the live wire L, the neutral wire N and the ground wire E, the input terminal of the driving switch circuit is electrically connected to the first output terminal of the microcontroller control circuit 7; the output terminal of the leakage protection circuit 3 is connected to the first output terminal of the microcontroller control circuit 7. The first input terminal is electrically connected; the input terminal of the overvoltage protection circuit 4 is electrically connected to the rectifier output terminal of the DC voltage stabilizing circuit 1, and the output terminal of the overvoltage protection circuit 4 is electrically connected to the second input terminal of the microcontroller control circuit 7 ; One end of the over-temperature protection circuit 5 is electrically connected to the neutral line N, and the other end of the over-temperature protection circuit 5 is electrically connected to the third input end of the single-chip microcomputer control circuit 7; the input end of the work indication circuit 6 is connected to the single-chip microcomputer control The second output terminal of the circuit 7 is electrically connected; the input terminal of the reset circuit 8 is electrically connected to the output terminal of the driving switch circuit, and the output terminal of the reset circuit 8 is electrically connected to the power circuit terminal of the leakage protection circuit 3. When the power is off, , the output terminal of the driving switch circuit is high level, and the reset circuit 8 resets the leakage protection circuit 3. When the power supply returns to normal, the output terminal of the driving switch circuit is low level, and the reset circuit 8 is disconnected, and the leakage protection circuit 3 is reset. Doesn't work.

During operation, when the leakage protection circuit 3 has an I _Δn leakage fault signal output, the first input terminal of the single-chip microcomputer control circuit 7 receives the I _Δn fault signal output by the single-chip microcomputer control circuit 7 and then processes it, and the first output terminal of the single-chip microcomputer control circuit 7 Output low level to the drive switch circuit, the drive switch circuit is disconnected, the second output terminal of the single chip control circuit 7 outputs high level to the work indication circuit 6, the LED indicator light sends out a flashing alarm signal, relay JK loses power, and the three groups are normally open The contacts are disconnected, thereby cutting off the power supply of N zero, L fire and PE ground poles until the leakage fault is completely eliminated. Only when the reset button is pressed again can the closing power supply be restored, effectively protecting personal safety; after tripping and power outage, reset The input terminal of circuit 8 is high level, and the output terminal of reset circuit 8 is low level, which means the power supply of the leakage protection circuit is cut off (short circuited); after the leakage fault is eliminated, press the RESET reset switch key, and the microcontroller controls circuit 7 The first output end and the second output end both output high level, the driving switch circuit is turned on, the relay JK is energized, the three groups of normally open contacts are closed and conduction restores the power supply state, the work indication circuit 6 returns to the normal light state, and resets The input terminal of circuit 8 switches to low level, and the output terminal of reset circuit 8 switches to high level, that is, the power supply is restored to the leakage protection circuit; because the working power supply of relay JK, leakage protection circuit 3 and microcontroller control circuit 7 all pass through DC Provided by the regulated power supply 1, under the low voltage AC50V state, the DC stabilized circuit 1 can still provide working voltage, so that the microcontroller control circuit 5, the relay switch circuit 2 and the leakage protection circuit 3 can work as usual, so this technical solution fully satisfies National standard requirements for AC50V low voltage operation.

In this embodiment, the microcontroller control circuit 7 includes a microcontroller U3 and a reset switch RESET; the model of the microcontroller U3 is XJLB8002, with a total of 8 pins. Pin 1 of the microcontroller U3 is connected to the neutral line N, and pin 2 of the microcontroller U3 is connected to the neutral line N. It is the first output terminal. Pin 3 of the microcontroller U3 is the first input terminal. Pin 6 of the microcontroller U3 is the second input terminal. Pin 5 of the microcontroller U3 is the third input terminal. Pin 8 of the microcontroller U3 is connected to the DC voltage stabilizing circuit 1. An output end of the reset switch RESET is electrically connected to pin 4 of the microcontroller U3, and the other end of the reset switch RESET is grounded; it also includes a work indication circuit 6, and the work indication circuit 6 includes a fourth resistor R4 and a light emitting diode. LED, the fourth resistor R4 is connected in series with the light-emitting diode LED, and one end is electrically connected to pin 7 of the microcontroller U3, and the other end is electrically connected to an output end of the DC voltage stabilizing circuit 1.

In the reset working state, if there is a power outage, the DC voltage stabilizing circuit 1 loses power, the microcontroller U3 and the relay JK lose power, and the three groups of normally open contacts are immediately disconnected; when the power supply is restored, as long as there is no leakage fault, the microcontroller U3 Pin 2 of the microcontroller U3 will output a high level, driving the switch circuit to conduct, and the three sets of normally open contacts will automatically close and conduct to return to the power supply working state. Pin 7 of the microcontroller U3 will output a low level, and the light-emitting diode LED will remain on. . When an I _Δn leakage fault occurs, the output end of the leakage protection circuit 3 will input the I _Δn leakage fault signal to pin 3 of the microcontroller U3. Pin 2 of the microcontroller U3 reverses from high potential to low potential, and the drive switch circuit is disconnected. , relay JK loses power, the three sets of normally open contacts immediately disconnect and stop supplying power to the electrical load, pin 7 of the microcontroller U3 outputs high level intermittently, and the light-emitting diode LED flashes to alarm; if there is an I _Δn leakage fault and a power outage occurs simultaneously When the power supply is restored, as long as the leakage fault is not eliminated, the microcontroller U3 will not output a reversal signal to the drive switch circuit, so the relay JK will always lose power, and the three sets of normally open contacts will always be in an open state and will not automatically close. ; When the leakage fault has been eliminated when the power supply is restored, pin 2 of the microcontroller U3 will automatically output a high potential, the drive switch circuit is turned on, the relay JK is energized, and the three sets of normally open contacts are closed to restore the power supply state, so it is very safe and reliable.

In this embodiment, the DC voltage stabilizing circuit 1 includes a rectifier diode D1, a first three-terminal voltage stabilizing block U1, a second three-terminal voltage stabilizing block U2, first to third electrolytic capacitors E1-E3, a third capacitor C3 and the sixth resistor R6; the anode of the rectifier diode D1 is electrically connected to the live wire L, and the cathode of the rectifier diode D1 is respectively connected to the positive terminal of the first electrolytic capacitor E1 and the input terminal and overvoltage of the first three-terminal voltage stabilizing block U1 The input terminal of the protection circuit 4 is electrically connected, the cathode of the rectifier diode D1 is the rectifier output terminal of the DC voltage stabilizing circuit 1, and the output terminal of the first three-terminal voltage stabilizing block U1 is respectively connected to the positive terminal of the third electrolytic capacitor E3 and the sixth resistor. One end of R6, the input end of the second three-terminal voltage stabilizing block U2 and one end of the relay JK are electrically connected. The output end of the first three-terminal voltage stabilizing block U1 provides the operating voltage for the relay JK. The other end of the sixth resistor R6 is for leakage current. Protection circuit 3 provides DC operating power; the negative terminal of the first electrolytic capacitor E1, the negative terminal of the third electrolytic capacitor E3 and the ground terminal of the first three-terminal voltage stabilizing block U1 are all electrically connected to the neutral line N, and the second three-terminal stable voltage The output end of the pressure block U2 is electrically connected to pin 8 of the microcontroller U3, the anode of the light-emitting diode LED, one end of the third capacitor C3 and the positive end of the second electrolytic capacitor E2. The output end of the second three-terminal voltage stabilizing block U2 is The microcontroller U3 provides a DC working power supply, and the other end of the third capacitor C3, the negative end of the second electrolytic capacitor E2, and the ground end of the second three-terminal voltage stabilizing block U2 are all grounded.

In this embodiment, the overvoltage protection circuit 4 includes a first resistor R1, a second resistor R2, a first capacitor C1 and a Zener diode DW; one end of the first resistor R1 is electrically connected to the anode of the rectifier diode D1 , this end of the first resistor R1 is the input end of the overvoltage protection circuit 4, the other end of the first resistor R1 is electrically connected to one end of the first capacitor C1 and the cathode of the Zener diode DW respectively, and the other end of the first capacitor C1 It is electrically connected to the neutral line N, the anode of the zener diode DW is electrically connected to one end of the second resistor R2 and pin 6 of the microcontroller U3, and the other end of the second resistor R2 is connected to the ground.

During operation, when the voltage at the rectifier output terminal of the DC voltage stabilizing circuit 1 is too high, that is, when the commercial AC power exceeds 295V, the voltage stabilizing diode DW will immediately avalanche short-circuit, pin 6 of the microcontroller U3 will immediately change from low potential to high potential, and pin 2 of the microcontroller U3 will Immediately reverses from high potential to low potential, the driving switch circuit is disconnected, and relay JK loses power and disconnects three sets of normally open contacts, which plays the role of overvoltage protection; when the city AC power is lower than 250V, the Zener diode DW recovers In the normal state, pin 6 of the microcontroller U3 returns to low potential, pin 2 of the microcontroller U3 outputs high level, the drive switch circuit is turned on, relay JK is powered to work, and the three sets of normally open contacts are closed to restore normal power supply.

In this embodiment, the over-temperature protection circuit 6 includes a third resistor R3, a second capacitor C2 and a negative temperature coefficient thermistor Rt; the second capacitor C2 and the negative temperature coefficient thermistor Rt are connected in parallel and have one end connected with The neutral line N is electrically connected, and the other end is electrically connected to pin 5 of the microcontroller U3 and one end of the third resistor R3. The other end of the third resistor R3 is electrically connected to the output end of the voltage stabilizing block U1.

During operation, when the temperature sensed by the negative temperature coefficient thermistor Rt is greater than 120°C, that is, when the resistance value of the thermistor Rt decreases to a certain value and pin 5 of the microcontroller U3 decreases from high potential to the set value, Pin 2 of the microcontroller U3 immediately reverses from high potential to low potential, and the drive switch circuit is disconnected. Relay JK loses power and disconnects three sets of normally open contacts, which plays the role of overvoltage protection. When the temperature drops below 50° , when the negative temperature coefficient thermistor Rt rises back to a certain value, pin 2 of the microcontroller U3 will output a high level, driving the switch circuit to conduct, the relay JK is powered to work, and the three sets of normally open contacts are closed to restore normal power supply.

In this embodiment, a second diode D2 is also included. Both ends of the second diode D2 are connected in parallel to both ends of the relay JK. The cathode of the second diode D2 is connected to the first three-terminal voltage regulator. The output terminal of block U1 is electrically connected; the driving switching circuit includes a first switching transistor Q1 and a fifth resistor R5. The base of the first switching transistor Q1 is electrically connected to pin 2 of the microcontroller U3 through the fifth resistor R5. The collector of the first switching transistor Q1 is electrically connected to the other end of the relay JK, and the emitter of the first switching transistor Q1 is grounded.

In this embodiment, the reset circuit 8 includes a second switching transistor Q2, a seventh resistor R7, an eighth resistor R8, and a fourth capacitor C4; the eighth resistor R8 and the fourth capacitor C4 are connected in parallel, with one end connected to the second switch respectively. The base of the transistor Q2 is electrically connected to one end of the seventh resistor R7, and the other end is grounded. The other end of the seventh resistor R7 is electrically connected to the collector of the first switching transistor Q1. The emitter of the second switching transistor Q2 is grounded. The collector of the switching transistor Q2 is electrically connected to the power circuit terminal of the leakage protection circuit 3 .

During operation, when pin 3 of the microcontroller U3 receives the I _Δn leakage signal, pin 2 of the microcontroller U3 immediately outputs a low level signal to the base of the first switching transistor Q1, the first switching transistor Q1 is disconnected, and the relay JK loses power. , the three sets of normally open contacts are disconnected to cut off the power supply and will not automatically restore power supply. At the same time, the base of the second switching transistor Q2 becomes high level, and the second switching transistor Q2 is turned on to short the power supply circuit terminal of the leakage protection circuit 3. The power is lost; the leakage protection latch circuit is forced to flip and reset. After the leakage fault is eliminated, press the reset switch RESET. Pin 2 of the microcontroller U3 outputs a high level signal to the base of the first switching transistor Q1, and the first switching transistor Q1 is turned on, relay JK is energized, and the three sets of normally open contacts of relay JK are turned on to continue supplying power to the load. At the same time, the base of the second switching transistor Q2 becomes low level, the second switching transistor Q2 is disconnected, and the leakage protection circuit Turn on the standby monitoring state when powered on.

In this embodiment, the leakage protection circuit 3 includes a first induction coil ZCT1, a second induction coil ZCT2, a test switch TEST, fifth to tenth capacitors C5 to C10, ninth to twelfth resistors R9 to R12, and Leakage fault monitoring chip U3; the model of the leakage fault monitoring chip U3 is RT54123B. The leakage fault monitoring chip U3 has 8 pins. Pins 1 and 2 of the leakage fault monitoring chip U3 are the first input terminals of the leakage protection circuit 3. Pins 2 and 3 of the fault monitoring chip U3 are the second input terminals of the leakage protection circuit 3. Pin 7 of the leakage fault monitoring chip U3 is the output terminal of the leakage protection circuit 3. Pin 4 of the leakage fault monitoring chip U3 is connected to the neutral line N. ; Both ends of the fifth capacitor C5 are electrically connected to pins 4 and 5 of the leakage fault monitoring chip U3, respectively. Both ends of the sixth capacitor C6 are electrically connected to pins 6 and 7 of the leakage fault monitoring chip U4 respectively. The seventh capacitor Both ends of C7 are electrically connected to pins 7 and 4 of the leakage fault monitoring chip U3 respectively; pin 8 of the leakage fault monitoring chip U3 is electrically connected to the other end of the sixth resistor R6 and the collector of the second switching transistor Q2. The six resistors R6 provide DC working voltage for the leakage fault monitoring chip U3; when the power is cut off, the base of the second switching transistor Q2 gets a high level, and the second switching transistor Q2 is turned on, which resets the leakage fault monitoring chip U3; when the problem is solved When the leakage problem occurs and normal power supply is restored, since the first switching transistor Q1 is turned on, the base of the second switching transistor Q2 is at a low level, the second switching transistor Q2 is disconnected, and the second switching transistor Q2 cannot afford the leakage fault monitoring chip U3. Function: The two ends of the eighth capacitor C8 and the eleventh resistor R11 are respectively electrically connected to pins 2 and 3 of the leakage fault monitoring chip U34, and the two ends of the tenth capacitor C10 and the twelfth resistor R12 are respectively connected to Pin 1 and pin 2 of the leakage fault monitoring chip U3 are electrically connected; one end of the ninth capacitor C9 is electrically connected to pin 2 of the leakage fault monitoring chip U3, and the other end is grounded; the first induction coil ZCT1 is set on the live wire L and the neutral line N, both ends of the first group of coils of the first induction coil ZCT1 are electrically connected to pins 2 and 3 of the leakage fault monitoring chip U3 respectively, and one end of the second group of coils of the first induction coil ZCT1 passes through the tenth The resistor R10 and the test switch TEST are electrically connected to the live wire L, and the other end of the second group of coils of the first induction coil ZCT1 is grounded; the second induction coil ZCT2 is set on the ground wire E, and both ends of the second induction coil ZCT2 Electrically connected to pins 1 and 2 of the leakage fault monitoring chip U3.

During operation, when the first induction coil ZCT1 or the second induction coil ZCT2 senses the I _Δn leakage fault signal, the leakage fault monitoring chip U3 immediately transmits the I _Δn leakage fault signal sensed by the first induction coil ZCT1 or the second induction coil ZCT2. After the amplification process, it is input to the input terminal 3 of the single-chip computer U3 through the ninth resistor R9. The second pin of the single-chip computer U3 immediately outputs a low level, and the first switching transistor Q1 is controlled to open circuit through the fifth resistor R5, and the relay JK loses power. JK's three sets of normally open contacts immediately disconnect and cut off the three-pole power supply, thus achieving the purpose of protecting personal safety. At this time, pin 7 of the microcontroller U3 outputs high level intermittently, and the light-emitting diode LED flashes to alarm; when the leakage fault is eliminated Afterwards, you must press the RESET reset switch key again, and then pin 2 of the microcontroller U3 will flip from low potential to high potential, relay JK will be energized, the first switch transistor Q1 will be turned on, and the three sets of normally open contacts will close and return to the load appliance. powered by.

Detection of leakage protection function: When the TEST test switch is pressed, the second group of coils of the first induction coil ZCT1 senses this simulated I _Δn leakage fault signal, and the first group of coils of the first induction coil ZCT1 inputs this signal to the leakage fault signal. Monitoring chip U3, the leakage fault monitoring chip U3 amplifies the sensed I _Δn leakage fault signal and inputs it to the input terminal 3 of the microcontroller U3. The pin 2 of the microcontroller U3 immediately outputs a low level and is input to the microcontroller through the fifth resistor R5. The base of the first switching transistor Q1, the first switching transistor Q1 is open circuit, the relay JK loses power, and the three sets of normally open contacts of the relay JK are immediately disconnected, achieving the purpose of detecting the working condition of the leakage protection plug.

The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those of ordinary skill in the art, various changes, modifications, substitutions and deformations can be made to these embodiments without departing from the principles and purposes of the present invention and still fall within the protection scope of the present invention.

Claims (2)

1. A semi-intelligent three-pole on-off leakage protection plug, including a DC voltage stabilizing circuit (1), a relay switching circuit (2), a leakage protection circuit (3) and a microcontroller control circuit (7); the DC voltage stabilizing circuit The input end of (1) is electrically connected to the city alternating current, and the output end of the DC voltage stabilizing circuit (1) provides working power for the relay switching circuit (2), leakage protection circuit (3) and microcontroller control circuit (7); the relay The switching circuit (2) includes a relay (JK) with three sets of normally open contacts and a driving switching circuit. One end of the relay (JK) is electrically connected to an output end of the DC voltage stabilizing circuit (1) to obtain DC operating power. , the other end of the relay (JK) is electrically connected to the output end of the drive switch circuit. The three sets of normally open contacts of the relay (JK) are connected in series to the live wire L, neutral wire N and ground wire E respectively. The drive switch circuit The input end is electrically connected to the first output end of the single-chip microcomputer control circuit (7); the output end of the leakage protection circuit (3) is electrically connected to the first input end of the single-chip microcomputer control circuit (7); it is characterized in that it also includes an overvoltage Protection circuit (4), over-temperature protection circuit (5) and reset circuit (8); the input end of the over-voltage protection circuit (4) is electrically connected to the rectifier output end of the DC voltage stabilizing circuit (1), and the over-voltage protection The output end of the circuit (4) is electrically connected to the second input end of the microcontroller control circuit (7); one end of the over-temperature protection circuit (5) is electrically connected to the neutral line N, and the other end of the over-temperature protection circuit (5) It is electrically connected to the third input terminal of the microcontroller control circuit (7); the input terminal of the reset circuit (8) is electrically connected to the output terminal of the drive switch circuit, and the output terminal of the reset circuit (8) is connected to the leakage protection circuit (3) The power circuit end is electrically connected, and when the power is cut off, the reset circuit (8) resets the leakage protection circuit (3); The reset circuit (8) includes a second switching transistor (Q2), a seventh resistor (R7), an eighth resistor (R8) and a fourth capacitor (C4); the eighth resistor (R8) and the fourth capacitor (C4) After parallel connection, one end is electrically connected to the base of the second switching transistor (Q2) and one end of the seventh resistor (R7), the other end is grounded, and the other end of the seventh resistor (R7) is electrically connected to the output end of the driving switching circuit. The emitter of the second switching transistor (Q2) is grounded, and the collector of the second switching transistor (Q2) is electrically connected to the power circuit end of the leakage protection circuit (3); The single-chip computer control circuit (7) includes a single-chip computer (U3) and a reset switch (RESET); the model of the single-chip computer (U3) is XJLB8002, with a total of 8 pins. Pin 1 of the single-chip computer (U3) is connected to the neutral line N. Pin 2 of (U3) is the first output terminal, pin 3 of the microcontroller (U3) is the first input terminal, pin 6 of the microcontroller (U3) is the second input terminal, and pin 5 of the microcontroller (U3) is the third input terminal. , pin 8 of the microcontroller (U3) is electrically connected to an output end of the DC voltage stabilizing circuit (1), one end of the reset switch (RESET) is electrically connected to pin 4 of the microcontroller (U3), and the other end of the reset switch (RESET) is connected to ground. ; Also includes a work indication circuit (6). The work indication circuit (6) includes a fourth resistor (R4) and a light-emitting diode (LED). The fourth resistor (R4) and the light-emitting diode (LED) are connected in series and one end is connected to the microcontroller ( Pin 7 of U3) is electrically connected, and the other end is electrically connected to an output end of the DC voltage stabilizing circuit (1); The DC voltage stabilizing circuit (1) includes a rectifier diode (D1), a first three-terminal voltage stabilizing block (U1), a second three-terminal voltage stabilizing block (U2), and first to third electrolytic capacitors (E1-E3). , the third capacitor (C3) and the sixth resistor (R6); the anode of the rectifier diode (D1) is electrically connected to the live wire L, and the cathode of the rectifier diode (D1) is respectively connected to the positive terminal and the positive terminal of the first electrolytic capacitor (E1). The input terminal of the first three-terminal voltage stabilizing block (U1) is electrically connected to the input terminal of the overvoltage protection circuit (4). The cathode of the rectifier diode (D1) is the rectifier output terminal of the DC voltage stabilizing circuit (1). The output terminal of the terminal voltage stabilizing block (U1) is connected to the positive terminal of the third electrolytic capacitor (E3), one end of the sixth resistor (R6), the input terminal of the second three-terminal voltage stabilizing block (U2) and the relay (JK). One end of the resistor is electrically connected, the first three-terminal voltage stabilizing block (U1) provides working voltage for the relay (JK), and the other end of the sixth resistor (R6) provides DC working power for the leakage protection circuit (3); the first electrolytic capacitor ( The negative terminal of E1), the negative terminal of the third electrolytic capacitor (E3) and the ground terminal of the first three-terminal voltage stabilizing block (U1) are all electrically connected to the neutral line N, and the output of the second three-terminal voltage stabilizing block (U2) The terminals are electrically connected to pin 8 of the microcontroller (U3), the anode of the light-emitting diode (LED), one terminal of the third capacitor (C3) and the positive terminal of the second electrolytic capacitor (E2), and the other terminal of the third capacitor (C3) , the negative terminal of the second electrolytic capacitor (E2) and the ground terminal of the second three-terminal voltage stabilizing block (U2) are both grounded; The overvoltage protection circuit (4) includes a first resistor (R1), a second resistor (R2), a first capacitor (C1) and a voltage stabilizing diode (DW); one end of the first resistor (R1) is connected to the DC voltage stabilizing The rectifier output end of circuit (1) is electrically connected, the other end of the first resistor (R1) is electrically connected to one end of the first capacitor (C1) and the cathode of the Zener diode (DW) respectively, and the other end of the first capacitor (C1) One end is electrically connected to the neutral line N, the anode of the Zener diode (DW) is electrically connected to one end of the second resistor (R2) and pin 6 of the microcontroller (U3), and the other end of the second resistor (R2) is connected to ground; The over-temperature protection circuit (5) includes a second capacitor (C2), a third resistor (R3) and a negative temperature coefficient thermistor (Rt); the second capacitor (C2), the third resistor (R3) and a negative temperature coefficient thermistor (Rt). After the coefficient thermistor (Rt) is connected in parallel, one end is electrically connected to the neutral line N, and the other end is electrically connected to pin 5 of the microcontroller (U3). 2. The semi-intelligent three-pole on-off leakage protection plug according to claim 1, characterized in that it also includes a second diode (D2), and both ends of the second diode (D2) are connected in parallel to a relay. (JK), and the cathode of the second diode (D2) is electrically connected to the output terminal of the first three-terminal voltage stabilizing block (U1); the driving switch circuit includes a first switching transistor (Q1) and a third Five resistors (R5), the base of the first switching transistor (Q1) is electrically connected to pin 2 of the microcontroller (U3) through the fifth resistor (R5), and the collector of the first switching transistor (Q1) is connected to the relay (JK ) is electrically connected to the other end, the collector of the first switching transistor (Q1) is also electrically connected to the second switching transistor (Q2) through the seventh resistor (R7), and the emitter of the first switching transistor (Q1) is grounded.