CN114865589B

CN114865589B - Leakage protector

Info

Publication number: CN114865589B
Application number: CN202210392609.2A
Authority: CN
Inventors: 朱伟民; 徐雷; 邓晓军
Original assignee: WUXI YOUDA ELECTRONICS CO Ltd
Current assignee: WUXI YOUDA ELECTRONICS CO Ltd
Priority date: 2022-04-14
Filing date: 2022-04-14
Publication date: 2023-04-07
Anticipated expiration: 2042-04-14
Also published as: CN114865589A

Abstract

The present invention provides an earth leakage protection device, comprising: the self-checking protection unit can simulate a leakage current signal by controlling the conduction of the first switch unit and acquire the level state of the first conductive end of the third switch unit at the self-checking stage, and if the current level state of the first conductive end of the third switch unit is a low level, the simulated leakage current detection is judged to pass, so that the complete detection of the leakage current signals of the positive and negative half cycles of the live wire/zero wire is realized, and the danger caused by the fact that the leakage protection signal cannot be normally triggered to cut off the connection between the live wire/zero wire and the load due to the fact that a control chip on a board card or peripheral components fail cannot detect the leakage current signal of the live wire/zero wire is avoided.

Description

Leakage protector

Technical Field

The invention relates to the technical field of leakage protectors, in particular to a leakage protection device.

Background

Since the first electrocution death accident in the world, the safety power utilization problem comes into the sight of scientists, and the research on the leakage protector aiming at preventing the human body from electrocution is carried out. The voltage action type leakage protector and the current action protector are researched in sequence, and the leakage protector plays a positive and effective role in preventing human body from getting an electric shock, so that the electric shock leakage protector device is generally accepted all over the world and is actively put into the research of the technology, and a large number of related novel products are continuously emerged.

Although the development of the leakage protector is late in China, the development speed is high. From the first earth leakage protector in the later stage of the sixties in the twentieth century through the approval of national identification, a high-sensitivity, quick-action and electronic current-action type earth leakage protection circuit breaker has been developed in the eighties in the twentieth century, and a fixed-point production enterprise has been established, so that the three-level protection of earth leakage and electric shock of a low-voltage power grid in China is realized, and the earth leakage and electric shock accidents are effectively controlled.

Most of the existing household leakage protector control devices in the current market can only detect and protect leakage current signals on a live wire/zero line under the normal condition of the leakage protector device, and when the leakage protector device self fails due to external reasons, the leakage current signals on the live wire/zero line cannot be detected and protected, so that great personal and property loss is easily caused. Therefore, customers in the market put forward requirements, the leakage protector can not only detect leakage current on the live wire/zero line, but also can periodically detect the leakage protector, and when the leakage protector control circuit is damaged due to external reasons, the leakage protector also needs to be capable of outputting corresponding protection trigger signals to cut off connection between the live wire/zero line and the load.

Therefore, companies in the market have provided corresponding control devices with self-checking leakage protectors, the devices are used for simulating leakage current signals in the negative half cycle of a live wire to detect whether the leakage protector devices are normally tripped or not, the purpose of doing so is to ensure that tripping coils can not cause tripping triggering problems in the negative half cycle simulation self-checking of the live wire, but the method can not detect the leakage current signals in the positive and negative half cycles of the live wire, and meanwhile, devices such as silicon controlled rectifiers and the like must also select high-voltage devices, and because the anodes of the silicon controlled rectifiers are directly connected to the live wire through the tripping coils.

Disclosure of Invention

The invention aims to provide a leakage protection device to solve at least one of the problems that the existing leakage protector cannot detect leakage signals of positive and negative half cycles of a live wire/zero wire, and the cost is overhigh due to limited selection of some switching devices in the leakage protector.

To solve the above technical problem, the present invention provides an earth leakage protection device, including: the device comprises an induction unit, a leakage detection unit, a self-checking protection unit, a rectification unit, a voltage stabilization unit, a voltage clamping unit, a sampling unit, a tripping unit, a first current limiting unit, a second current limiting unit, a first switch unit, a second switch unit and a third switch unit, wherein,

one end of the electric leakage detection unit is connected with the sensing unit, and the other end of the electric leakage detection unit is connected with the self-checking protection unit;

the self-checking protection unit is also respectively connected with the control end of the first switch unit, the control end of the second switch unit, the control end of the third switch unit and one end of the sampling unit; a first conductive terminal of the first switching unit is coupled to a positive output terminal of the rectifying unit through the first current limiting unit, and a second conductive terminal of the first switching unit is grounded; the first conductive terminal of the second switch unit is coupled to the trip unit, the second conductive terminal of the second switch unit is coupled to the first conductive terminal of the third switch unit, and the second conductive terminal of the third switch unit is grounded; the other end of the sampling unit is coupled to the first conductive end of the third switching unit;

the voltage clamping unit is coupled to the control end of the second switch unit;

one end of the second current limiting unit is coupled to the first conductive end of the second switch unit, and the other end of the second current limiting unit is coupled to the control end of the second switch unit;

the input end of the voltage stabilizing unit is coupled to the positive output end of the rectifying unit, and the output end of the voltage stabilizing unit is respectively coupled to the electric leakage detection unit, the voltage clamping unit and the self-checking protection unit so as to supply power to the electric leakage detection unit, the voltage clamping unit and the self-checking protection unit; the negative output end of the rectifying unit is grounded;

wherein, in a self-test phase, the self-test protection unit is configured to: firstly, the self-checking protection unit controls the first switch unit to be disconnected, and then when the self-checking protection unit detects that the current phase of an external live wire/zero line is in a positive half cycle or a negative half cycle, the self-checking protection unit controls the second switch unit and the third switch unit to be disconnected; then, the self-checking protection unit pulls the first conducting end of the third switching unit to a high level state through the sampling unit, then controls the first switching unit to be conducted to simulate a leakage current signal, and if the self-checking protection unit receives the leakage current signal sent by the induction unit through the leakage detection unit, a control signal is sent to the control end of the third switching unit to control the third switching unit to be conducted; finally, the current level state of the first conductive end of the third switching unit is obtained through a sampling unit, and at the moment, if the current level state of the first conductive end of the third switching unit is a low level, the analog leakage detection is judged to be passed; if the current level state of the first conductive end of the third switching unit is a high level, judging that the analog leakage detection fails;

in a non-self-checking stage, the control terminal of the second switching unit receives a high-level signal of the rectifying unit through the second current limiting unit and the tripping unit, and at this time, the second switching unit is in a conducting state, and the self-checking protection unit is configured to: the self-checking protection unit controls the first switch unit and the third switch unit to be disconnected, and when the self-checking protection unit receives a leakage current signal sent by the induction unit through the leakage detection unit, the self-checking protection unit sends a control signal to the third switch unit to control the third switch unit to be switched on, so that the tripping unit is switched to be in a disconnected state from a conducting state.

Optionally, in the leakage protection device, the self-test protection unit includes: the first port of the logic decision module is connected with the other end of the electric leakage detection unit; the second port of the logic decision module is connected with the control end of the first switch unit; a third port of the logic decision module is connected with the control end of the second switch unit; a fourth port of the logic decision module is connected with the control end of the third switch unit; a fifth port of the logic decision module is connected with the phase detection module; a sixth port of the logic decision module is connected with one end of the sampling unit to send a high level signal or a low level signal to the sampling unit; the phase detection module is connected with one end of the sampling unit to receive the current potential of the first conducting end of the third switching unit fed back by the sampling unit.

Optionally, in the leakage protection device, the self-test protection unit further includes: and the alarm module is connected with the logic judgment module, wherein in a self-checking stage, when the simulation leakage detection fails, the phase detection module receives a high-level signal of the first conductive end of the third switch unit through the sampling unit and feeds the high-level signal back to the logic judgment module, and at the moment, the logic judgment module outputs a self-checking fault signal to the alarm module.

Optionally, in the leakage protection device, the self-test protection unit further includes: the alarm time detection module is respectively connected with the alarm module and the logic judgment module and is used for detecting the alarm duration time output by the alarm module; if the current alarm duration time exceeds a preset time threshold value, an overtime signal is sent to the logic decision module.

Optionally, in the leakage protection device, the self-test protection unit further includes: and the execution module is connected with the alarm module and is used for receiving a driving signal output by the alarm module so as to send out a corresponding alarm indication.

Optionally, in the leakage protection device, the first switch unit is a triode or an MOS transistor; the second switch units are both triodes or MOS tubes; the third switching unit is a thyristor.

Optionally, in the electrical leakage protection device, the electrical leakage protection device further includes: and the backflow preventing unit is connected between the positive output end of the rectifying unit and the voltage stabilizing unit in series.

Optionally, in the earth leakage protection device, the reverse flow preventing unit includes: the positive pole of the diode is connected with the positive output end of the rectifying unit, the negative pole of the diode is connected with one end of the current-limiting resistor, the other end of the current-limiting resistor is connected with the input end of the voltage stabilizing unit, the positive pole of the capacitor is connected with the input end of the voltage stabilizing unit, and the negative pole of the capacitor is grounded.

Optionally, in the leakage protection device, the trip unit is a trip coil; the induction unit is an induction coil.

Optionally, in the leakage protection device, the first current limiting unit and the second current limiting unit are both current limiting resistors.

In summary, the present invention provides an earth leakage protection device, comprising: the self-checking protection circuit comprises an induction unit, a leakage detection unit, a self-checking protection unit, a rectification unit, a voltage stabilization unit, a voltage clamping unit, a sampling unit, a tripping unit, a first current limiting unit, a second current limiting unit, a first switch unit, a second switch unit and a third switch unit, wherein in the self-checking stage, firstly, the self-checking protection unit controls the first switch unit to be disconnected, and then when the self-checking protection unit detects that the current phase of an external live wire/zero line is in a positive half cycle or a negative half cycle, the self-checking protection unit controls the second switch unit and the third switch unit to be disconnected; then, the self-test protection unit pulls the first conductive end of the third switch unit to a high level state through the sampling unit, then controls the first switch unit to be conducted to simulate a leakage current signal, and if the self-test protection unit receives the leakage current signal sent by the induction unit through the leakage current detection unit, sends a control signal to the control end of the third switch unit to control the third switch unit to be conducted; finally, the current level state of the first conductive end of the third switching unit is obtained through the sampling unit, and at the moment, if the current level state of the first conductive end of the third switching unit is a low level, the analog leakage detection is judged to be passed; and if the current level state of the first conductive end of the third switching unit is a high level, judging that the analog leakage detection fails. The technical scheme at least comprises the following advantages:

the device provided by the application can not only normally detect the leakage current signal on the live wire/zero line in a non-self-checking stage, but also simulate the leakage current signal of the positive and negative half cycles of the live wire/zero line in a self-checking stage, and synchronously detect whether the leakage protector device can normally work or not, and simultaneously the device can also detect and judge the failure condition of peripheral components in the self-checking stage, so that the device can completely avoid the danger caused by the fact that the leakage current signal of the live wire/zero line cannot be detected after a control chip on a board card or the peripheral components fail, and the leakage protection signal cannot be normally triggered to cut off the connection between the live wire/zero line and a load; the problem that the conventional leakage protection device cannot detect leakage signals of positive and negative half cycles of a live wire/zero line is solved, and the reliability and accuracy of leakage current detection are improved.

Furthermore, the device reasonably controls the number of peripheral components, has simple structure, and ensures that the selection range of the third switch unit is not limited because the third switch unit is connected with the tripping unit through the second switch unit, and low-voltage type switch devices can be selected, thereby greatly reducing the production cost and being beneficial to large-scale industrial production.

Drawings

Fig. 1 is a schematic structural diagram of a leakage protection device according to a first embodiment of the present invention;

fig. 2 is a schematic structural diagram of a leakage protection device in which a first switch unit and a second switch unit are both MOS transistors and a third switch unit is a thyristor according to a first embodiment of the present invention;

fig. 3 is a schematic diagram of a first self-checking waveform of the earth leakage protection device according to the first embodiment of the invention;

fig. 4 is a schematic diagram of a second self-test waveform of the earth leakage protection device according to the first embodiment of the invention;

fig. 5 is a schematic diagram of a third self-test waveform of the earth leakage protection device according to the first embodiment of the invention;

fig. 6 is a schematic structural diagram of a leakage protection device in which the first switch unit and the second switch unit are both triodes and the third switch unit is a thyristor according to a second embodiment of the present invention;

wherein the reference numerals are as follows:

10-an induction unit, 20-a leakage detection unit, 30-a self-checking protection unit, 40-a rectification unit, 50-a voltage stabilization unit, 60-a voltage clamping unit, 70-a sampling unit, 80-a tripping unit, 90-a reverse flow prevention unit, R1-a first current limiting unit, R2-a second current limiting unit, S1/Q1-a first switch unit, S2/Q2-a second switch unit, and S3/Q3-a third switch unit;

31-a logic decision module, 32-a phase detection module, 33-an alarm module, 34-an alarm time detection module and 35-an execution module.

Detailed Description

The earth leakage protection device proposed by the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings are intended to show different emphasis, sometimes in different proportions.

Example one

Referring to fig. 1, fig. 1 is a schematic structural diagram of a leakage protection device according to a first embodiment of the present invention, where the leakage protection device includes: the circuit comprises a sensing unit 10, a leakage detection unit 20, a self-checking protection unit 30, a rectification unit 40, a voltage stabilization unit 50, a voltage clamping unit 60, a sampling unit 70, a tripping unit 80, a first current limiting unit R1, a second current limiting unit R2, a first switching unit S1, a second switching unit S2 and a third switching unit S3.

In a first embodiment, the leakage protection device further includes: and the backflow preventing unit 90 is connected between the positive output end of the rectifying unit 40 and the input end of the voltage stabilizing unit 50 in series, and the backflow preventing unit 90 is connected between the positive output end of the rectifying unit 40 and the input end of the voltage stabilizing unit 50 in series.

Specifically, one end of the leakage detecting unit 20 is connected to the sensing unit 10, and the other end of the leakage detecting unit 20 is connected to the self-checking protecting unit 30; the self-checking protection unit 30 is further connected to the control terminal of the first switch unit S1, the control terminal of the second switch unit S2, the control terminal of the third switch unit S3, and one end of the sampling unit 70, respectively; a first conductive terminal of the first switching unit S1 is coupled to the positive output terminal of the rectifying unit 40 through the first current limiting unit R1, and a second conductive terminal of the first switching unit S1 is grounded; a first conductive terminal of the second switching unit S2 is coupled to the trip unit 80, a second conductive terminal of the second switching unit S2 is coupled to a first conductive terminal of the third switching unit S3, and a second conductive terminal of the third switching unit S3 is grounded; the other end of the sampling unit 70 is coupled to the first conductive terminal of the third switching unit S3. Further, the voltage clamping unit 60 is coupled to the control terminal of the second switching unit S2; one end of the second current limiting unit R2 is coupled to the first conductive end of the second switch unit S2, and the other end of the second current limiting unit R2 is coupled to the control end of the second switch unit S2.

Further, the input terminal of the voltage stabilizing unit 50 is coupled to the positive output terminal of the rectifying unit 40 through the backflow preventing unit 90, and the output terminal of the voltage stabilizing unit 50 is coupled to the leakage detecting unit 20, the voltage clamping unit 60 and the self-checking protecting unit 30 respectively to supply power to the leakage detecting unit 20, the voltage clamping unit 60 and the self-checking protecting unit 30; the negative output terminal of the rectifying unit 40 is grounded.

Preferably, the reverse flow preventing unit 90 includes: the rectifier circuit comprises a diode D1, a current-limiting resistor R3 and a capacitor C1, wherein the anode of the diode D1 is connected with the positive output end of the rectifying unit 40, the cathode of the diode D1 is connected with one end of the current-limiting resistor R3, the other end of the current-limiting resistor R3 is connected with the input end of the voltage stabilizing unit 50, the anode of the capacitor C1 is connected with the input end of the voltage stabilizing unit 50, and the cathode of the capacitor C1 is grounded.

Preferably, the trip unit 80 may be a trip coil; the induction unit 10 may be an induction coil.

In the first embodiment, the first current limiting unit R1 and the second current limiting unit R2 may be both current limiting resistors.

Further, the self-test protection unit 30 includes: a logic decision module 31 and a phase detection module 32 connected to each other, wherein a first port of the logic decision module 31 is connected to the other end of the leakage detection unit 20; a second port of the logic decision module 31 is connected to the control end of the first switch unit S1; a third port of the logic decision module 31 is connected to the control end of the second switch unit S2; a fourth port of the logic decision module 31 is connected to the control end of the third switching unit S3; a fifth port of the logic decision module 31 is connected to the phase detection module 32; a sixth port of the logic decision module 31 is connected to one end of the sampling unit 70 to send a high level signal or a low level signal to the sampling unit 70; the phase detection module 32 is connected to one end of the sampling unit 70 to receive the current potential of the first conducting terminal of the third switching unit S3 fed back by the sampling unit 70. The phase detection module 32 is further configured to detect a current phase of the external live/neutral line.

Further, the signal transmission between the phase detection module 32 and the logic decision module 31 has bidirectional conductivity, and the phase detection module 32 is mainly configured to receive a phase change signal and/or a voltage change signal (a current potential of the first conductive terminal of the third switching unit S3) of the external live wire/zero line through the sampling unit 70, and to feed back a current phase of the external live wire/zero line to the logic decision module 31.

Preferably, the self-test protection unit 30 may further include: and the alarm module 33, the alarm module 33 is connected to the logic decision module 31, wherein, in a self-checking stage, when the analog leakage detection fails, the phase detection module 32 receives a high level signal of the first conductive end of the third switching unit S3 through the sampling unit 70 and feeds the high level signal back to the logic decision module 31, and at this time, the logic decision module 31 outputs a self-checking fault signal to the alarm module 33.

Preferably, the self-test protection unit 30 may further include: the alarm time detection module 34, the alarm time detection module 34 is respectively connected to the alarm module 33 and the logic decision module 31, and the alarm time detection module 34 is configured to detect an alarm duration output by the alarm module 33 and output an timeout signal to the logic decision module 31; if the current alarm duration time exceeds a preset time threshold, the alarm time detection module 34 will send an overtime signal to the logic decision module 31. After the logic decision module 31 receives the timeout signal, the third switching unit S3 is correspondingly controlled to be turned on, so that the trip unit (trip coil) 80 disconnects the live wire/zero line from the load.

Further, the self-test protection unit 30 may further include: an executing module 35, where the executing module 35 is connected to the alarm module 33, and the executing module 35 is configured to receive a driving signal output by the alarm module 33 to send a corresponding alarm indication, that is, after the alarm module 33 receives a self-checking fault signal output by the logic determining module 31, the executing module 35 sends a driving signal to the executing module 35, and the executing module 35 is driven by the alarm module 33 to send an alarm indication. Specifically, the execution module 35 may be an LED lamp or a buzzer or other components.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a leakage protection device in which a first switch unit and a second switch unit are both MOS transistors, and a third switch unit is a thyristor according to a first embodiment of the present invention, where the first switch unit is an MOS transistor; the second switch unit is also an MOS tube; the third switching unit is a thyristor (silicon controlled rectifier). Assume that the clamping voltage of the voltage clamping unit 60 is Vz, the turn-on threshold of the NMOS transistor is Vth, and the live/neutral line voltage is VL. Thus, in the non-self-test phase: when the live wire voltage VL < Vz, the grid voltage of the NMOS tube Q2 is equal to the live wire/zero wire voltage VL, and the source voltage of the NMOS tube Q2 is equal to VL-Vth; when the voltage VL of the live wire/zero line is larger than or equal to Vz, the grid voltage of the MOS tube Q2 is clamped at Vz, the source voltage of the MOS tube Q2 is equal to Vz-Vth, and the source voltage of the NMOS tube Q2 is connected with the anode of the thyristor Q3, so that the anode voltage of the thyristor Q3 is Vz-Vth.

The working principle of the leakage protection device of the embodiment of the application is as follows:

in a self-test phase, the self-test protection unit 30 is configured to: the self-test protection unit 30 (the logic decision module 31) first controls the first switch unit S1/Q1 to be turned off; when the self-test protection unit 30 (the phase detection module 32) detects that the current phase of the external live wire/zero wire is in a positive half cycle or a negative half cycle, the self-test protection unit 30 (the logic decision module 31) controls the second switching unit S2/Q2 and the third switching unit S3/Q3 to be switched off; then, the self-test protection unit 30 (the logic decision module 31) pulls the first conductive terminal of the third switching unit S3/Q3 to a high level state (for example, to 5V) through the sampling unit 70, and then the self-test protection unit 30 (the logic decision module 31) controls the first switching unit S1/Q1 to be turned on to simulate a leakage current signal; if the phase detection module 32 detects that the electrical phase of the external live wire/zero line is within the positive half cycle or within the negative half cycle, the control end of the first switch unit S1/Q1 is not sent a control signal, that is, the first switch unit S1/Q1 is always controlled to keep the off state. If the self-test protection unit 30 (logic decision module 31) receives the leakage current signal sent by the sensing unit 10 through the leakage current detection unit 20, a control signal is sent to the control end of the third switching unit S3/Q3 to control the conduction of the third switching unit S3/Q3; finally, the phase detection module 32 obtains the current level state of the first conducting terminal of the third switching unit S3/Q3 through the sampling unit 70, and at this time, if the current level state of the first conducting terminal of the third switching unit S3/Q3 is a low level, it is determined that the analog leakage detection is passed; and if the current level state of the first conductive end of the third switching unit S3/Q3 is a high level, judging that the analog leakage detection fails. It can also be seen that, in the self-checking stage, when the simulated leakage is performed in the positive half cycle or the negative half cycle of the live wire/zero line, the tripping unit 80 is not triggered to trip due to the positions of the second switch unit S2/Q2 and the third switch unit S3/Q3 and the working principle of the whole simulated leakage.

In a non-self-test phase, the control terminal of the second switching unit S2/Q2 receives a high-level signal of the rectifying unit 40 through the second current limiting unit R2 and the tripping unit 80, and at this time, the second switching unit S2/Q2 is in a conducting state, and the self-test protection unit 30 is configured to: the self-checking protection unit 30 (logic decision module 31) controls the first switching unit S1/Q1 and the third switching unit S3/Q3 to be disconnected, and meanwhile, the phase detection module 32 obtains the voltage of the first conductive end of the third switching unit S3/Q3 through the sampling unit 70, and determines the voltage change and the phase change on the live wire/zero wire; when the self-checking protection unit 30 (logic decision module 31) receives a leakage current signal (leakage current signal on the live wire/zero wire) sent by the sensing unit 10 through the leakage detection unit 20, the self-checking protection unit 30 (logic decision module 31) sends a control signal to the third switching unit S3/Q3 to control the conduction of the third switching unit S3/Q3, so that the tripping unit 80 is switched from a conduction state to a disconnection state, thereby cutting off the connection between the live wire/zero wire and the electric load.

In this embodiment, the rectifying unit 40 mainly has three functions, namely, converting the ac voltage of the utility power into the dc voltage, simulating the leakage current on the live line/zero line through the first switching unit Q1 in the self-checking stage, and providing the tripping current for the tripping unit 80.

Further, in the reverse-flow prevention unit 90, the capacitor C1 mainly functions to store energy in the power supply, and the diode D1 mainly functions to prevent the charges on the capacitor C1 from being discharged reversely through the current-limiting resistor R3, so that in the self-checking stage, when the first switch unit Q1 simulates leakage of a live wire or a zero wire, the voltage VDD at the power supply end of the voltage stabilization unit 50 is not affected. Further, the purpose of the current limiting resistor R3 is to reduce the current and voltage, and provide power to the voltage stabilizing unit 50.

In addition, the first current limiting unit R1 mainly functions to limit the maximum analog leakage current during the self-test phase.

In this embodiment, the second current limiting unit R2 may provide a bias to the control terminal of the second switching unit S2/Q2 during the non-self-test stage, so as to turn on the second switching unit S2/Q2, but at the same time, due to the existence of the voltage clamping unit 60, the highest voltage of the control terminal of the second switching unit S2/Q2 is clamped at the voltage Vz. For example, the following steps are carried out: assuming that the clamping voltage of the voltage clamping unit 60 is Vz =20V, the second switching unit S2/Q2 of the present embodiment uses an NMOS transistor, the threshold voltage of the NMOS transistor is Vth =1V, and the voltage of the live line/zero line is VL. Thus, in the non-self-test phase: when the voltage VL of the live wire/zero wire is less than 20V, the gate voltage of the NMOS transistor is equal to the voltage VL of the live wire/zero wire, the source voltage of the NMOS transistor is equal to VL-Vth = (VL-1) V, when the voltage VL of the live wire/zero wire is greater than or equal to 20V, the gate voltage of the NMOS transistor is clamped at Vz =20v, the source voltage of the NMOS transistor is equal to VL-Vth = (VL-1) =19V (the source voltage of the NMOS transistor is also the voltage at the first conductive terminal/upper terminal of the third switching unit S3/Q3).

From the above example, it can be seen that: and in the non-self-checking stage, the highest voltage at the upper end of the third switching unit S3/Q3 is clamped at Vz-Vth, and in the self-checking stage, the second switching unit S2/Q2 is disconnected, so that the upper end of the third switching unit S3/Q3 is completely isolated and disconnected from a live wire/zero wire. Therefore, in any case, the voltage at the upper end of the third switching unit S3/Q3 does not exceed Vz, so that when the third switching unit S3/Q3 is selected, a low-voltage switching device (such as a low-voltage thyristor) can be selected, thereby reducing the cost and improving the reliability.

In this embodiment, the self-checking protection unit 30 can accurately determine the time interval of the positive half cycle of the live wire/zero line at the self-checking stage according to the phase detection module 32, and send a signal control at the positive half cycle of the live wire/zero line to turn on the first switch unit S1/Q1 to extract the current of the positive output end of the rectification unit 40, so that the live wire leakage can be simulated at the positive half cycle of the live wire and the self-checking can be realized, and the zero line leakage can be simulated at the positive half cycle of the zero line and the self-checking can be realized.

In this embodiment, in the self-checking stage, if the first self-checking passes, the following settings may be set: waiting for 10 minutes and then performing the next self-checking, and performing the self-checking circularly every 10 minutes; if the self-checking fails, the self-checking is continuously circulated for 4 times, and if the self-checking fails for 4 times, the execution module 35 of the self-checking protection unit 30 sends an alarm indication. Specifically, when the leakage self-test fails for a plurality of consecutive times (for example, 4 times), the logic decision module 31 may send a corresponding control signal to the alarm module 33, and the alarm module 33 outputs a corresponding driving signal to drive the execution module 35 to send a corresponding alarm indication (prompt).

Further, if the alarm time detection module 34 detects that the duration of the alarm module sending the alarm driving signal to the execution module exceeds 3 minutes (in this embodiment, the time threshold may be set to 3 minutes), the self-checking protection unit 30 controls the third switch unit S3/Q3 to be turned on, so that the trip coil 80 disconnects the live wire/null wire from the load, and thus, the loss caused by the failure of the leakage protection device and the failure of the leakage detection device due to the failure of the leakage protection device can be avoided.

In this embodiment, the leakage protection device can also detect whether some peripheral components in the device are damaged, and the specific detection is as follows:

(1) If the rectifying unit 40 is damaged, the voltage regulator unit 50 will gradually decrease the output voltage VDD to 0V due to insufficient power supply, and trigger the under-voltage protection function in the voltage regulator unit 50 in the process of gradually decreasing the power supply voltage VDD, and the voltage regulator unit 50 will send out a corresponding under-voltage protection signal, so that the apparatus can detect whether the rectifying unit 40 is damaged.

(2) If the third switching unit S3/Q3 is damaged due to short circuit, the phase detection module 32 can detect that the upper end (first conductive end) of the third switching unit S3/Q3 is always at a low level through the sampling unit 70, so that the apparatus can detect whether the third switching unit S3/Q3 is damaged due to short circuit.

(3) If the third switch unit S3/Q3 is open-circuited and damaged, the phase detection module 32 can detect that the upper end potential of the third switch unit S3/Q3 will be always at a high level through the sampling unit 70, so that the apparatus can determine that the switch S3 is open-circuited and damaged.

(4) If the second switch unit S2/Q2 is damaged due to short circuit, the phase detection module 32 can detect that the voltage at the upper end of the third switch unit S3/Q3 exceeds the preset maximum clamping voltage through the sampling unit 70, and can determine that the second switch unit S2/Q2 is damaged due to short circuit.

(5) If the second switch unit S2/Q2 is open-circuited and damaged, the phase detection module 32 can detect that the upper end voltage of the third switch unit S3/Q3 does not reach the periodically-changed voltage through the sampling unit 70, and can determine that the second switch unit S2/Q2 is open-circuited and damaged.

(6) If the trip unit 80 is damaged, the voltage clamping unit 60 detects that the control end of the second switching unit S2/Q2 is always at a low level, and may determine that the trip unit 80 is damaged.

(7) If the sensing unit 10 is damaged, in the self-test stage, the self-test protection unit 30 cannot receive the analog leakage current signal output by the leakage current detection unit 20, and it can be determined that the sensing unit 10 is damaged.

(8) If the first switch unit S1/Q1 is damaged due to short circuit, the leakage detecting unit 20 may continuously detect an alternate leakage signal from the live line/the zero line in the whole time period, so as to determine that the first switch unit S1/Q1 is damaged due to short circuit.

(9) If the first switch unit S1/Q1 is open-circuited and damaged, the leakage detection unit 20 cannot detect the leakage signal from the live line/zero line all the time in the self-test stage, and can determine that the first switch unit S1/Q1 is open-circuited and damaged.

Referring to fig. 3, fig. 3 is a schematic diagram of a first self-checking waveform of an earth leakage protection device according to an embodiment of the present invention, where ac waveforms t1 to t2 represent a positive half cycle of a live wire (i.e., a negative half cycle of a zero line), and ac waveforms t2 to t3 represent a negative half cycle of the live wire (i.e., a positive half cycle of the zero line), a rectifying unit 40 (a rectifying bridge) adopted in the embodiment is a single-phase rectifying circuit and is composed of four diodes, and a principle of the structure is to ensure that a voltage and a current direction at a positive output end of the rectifying bridge are unchanged in the entire period t1 to t3 of the ac.

In fig. 3, two times of self-checking are performed in one period of the alternating current, that is, one-time electric leakage self-checking is performed on the live wire/zero line respectively, the self-checking protection unit 30 can send out a high level signal to control the first switch unit S1/Q1 to switch on the analog live wire electric leakage signal within the time of the positive half cycle t 1-t 2 of the live wire in one period t 1-t 3 of the alternating current, and send out a high level signal to control the first switch unit S1/Q1 to switch on the analog zero line electric leakage signal within the time of the negative half cycle t 2-t 3 of the live wire, so the electric leakage detection unit 20 can also detect two adjacent same electric leakage signals within one period of the alternating current, and the self-checking protection unit 30 can also send out two same high level pulse signals within one period of the alternating current to control the conduction of the third switch unit S3/Q3. Whether the potential at the upper end of the third switching unit S3/Q3 is continuously pulled down twice or not is detected, if the potential at the upper end of the third switching unit S3/Q3 is continuously pulled down twice, the device simulates the leakage operation of a live wire/zero line from the outside, receives a corresponding leakage signal, and triggers a tripping signal, the whole self-checking loop works in a normal state, and the self-checking is passed; if the potential at the upper end of the third switch unit S3/Q3 is not pulled down twice continuously, the self-checking failure is indicated. In fig. 3, if the first self-test is passed, the system enters a continuous cycle self-test mode, that is, the live wire/zero wire leakage self-test is performed every t minutes, where a value range of t may be 8 minutes to 15 minutes, for example, t =10 minutes.

Further, referring to fig. 4, fig. 4 is a schematic diagram of a second self-checking waveform of the leakage protection device according to the first embodiment of the present invention, a live wire leakage self-checking is performed in one cycle of ac power, the self-checking protection unit 30 may send a high-level signal to control the first switch unit S1/Q1 to turn on the analog live wire leakage signal within a positive half cycle t 1-t 2 of the live wire in one cycle t 1-t 3 of ac power, so that the leakage detection module may also detect a live wire leakage signal within one cycle of ac power, and the self-checking protection unit 30 also sends a high-level pulse signal to control the third switch unit S3/Q3 to turn on within one cycle of ac power. Whether the potential at the upper end of the third switch unit S3/Q3 is pulled down or not is detected, if the potential at the upper end of the third switch unit S3/Q3 is pulled down, the device simulates the live wire leakage operation from the outside, receives a corresponding leakage signal, and triggers a tripping signal, the whole self-checking loop works in a normal state, and the self-checking is passed; if the potential at the upper end of the third switch unit S3/Q3 is not pulled low, the self-test fails. In fig. 4, if the first self-test passes, the system will enter a continuous cycle self-test mode, that is, a live wire leakage self-test is performed every t minutes, where the value of t may range from 8 minutes to 15 minutes, for example, t =10 minutes.

Further, referring to fig. 5, fig. 5 is a third schematic diagram of a self-checking waveform of the leakage protection device according to the first embodiment of the present invention, a zero line leakage self-checking is performed once in one cycle of ac power, the self-checking protection unit 30 may send a high-level signal to control the first switch unit S1/Q1 to turn on the simulated zero line leakage signal within a negative half cycle t2 to t3 of a live line in one cycle t1 to t3 of ac power, so that the leakage detection module may also detect a zero line leakage signal in one cycle of ac power, and the self-checking protection unit 30 may also send a high-level pulse signal to control the third switch unit S3/Q3 to turn on and off in one cycle of ac power. Whether the potential at the upper end of the third switch unit S3/Q3 is pulled down or not is detected, if the potential at the upper end of the third switch unit S3/Q3 is pulled down, the device is indicated to receive a corresponding leakage signal from the external simulation of zero line leakage operation, and then a tripping signal is triggered, the whole self-checking loop works normally, and the self-checking is passed; if the potential at the upper end of the third switch unit S3/Q3 is not pulled low, the self-test fails. In fig. 5, if the first self-test is passed, the system enters a continuous cycle self-test mode, that is, zero line leakage self-test is performed every t minutes, where a value range of t may be 8 minutes to 15 minutes, for example, t =10 minutes.

Example two

Referring to fig. 6, fig. 6 is a schematic structural diagram of a leakage protection device in which a first switch unit and a second switch unit of a second embodiment of the present invention are both triodes, and a third switch unit is a thyristor, where the first switch unit is a triode (NPN transistor); the second switch unit is also a triode (NPN tube); the third switching unit is a thyristor (silicon controlled rectifier).

Specifically, assume that the clamping voltage of the voltage clamping unit is Vz, the turn-on threshold of the NPN transistor is Vbe, and the voltage of the live line/neutral line is VL. Thus, in the non-self-test phase: when the live wire/zero line voltage VL is less than Vz, the base voltage of the NPN tube Q2 is equal to the live wire/zero line voltage VL, and the emitter voltage of the NPN tube Q2 is equal to VL-Vbe; when the live wire/zero line voltage VL is larger than Vz, the base voltage of the NPN tube Q2 is clamped at Vz, the emitter voltage of the NPN tube Q2 is equal to Vz-Vbe, and the anode voltage of the silicon controlled rectifier Q3 is VL-Vbe as the emitter of the NPN tube Q2 is connected with the anode of the silicon controlled rectifier Q3. Meanwhile, the base of the NPN transistor Q2 needs a certain base current to provide bias, so the resistance of the second current limiting unit R2 cannot be too large.

It should be noted that, descriptions of the same units/modules in the leakage protection devices of the second embodiment and the first embodiment are not repeated, and please refer to the first embodiment.

In conclusion, the device provided by the application can not only normally detect the leakage current signal on the live wire/zero line in a non-self-checking stage, but also simulate the leakage current signal of the positive and negative half cycles of the live wire/zero line in a self-checking stage, and synchronously detect whether the leakage protector device can normally work or not, and simultaneously the device can also detect and judge the failure condition of the peripheral components in the self-checking stage, so that the device can completely avoid the danger caused by the fact that the leakage current signal of the live wire/zero line cannot be detected after the control chip on the board card or the peripheral components fail, and the leakage protection signal cannot be normally triggered to cut off the connection between the live wire/zero line and the load; the problem that the existing traditional leakage protection device cannot detect leakage signals of positive and negative half cycles of a live wire/zero line is solved, and the reliability and the accuracy of leakage current detection are improved. Furthermore, the device reasonably controls the number of peripheral components, has simple structure, and ensures that the selection range of the third switch unit is not limited because the third switch unit is connected with the tripping unit through the second switch unit, and low-voltage type switch devices can be selected, thereby greatly reducing the production cost and being beneficial to large-scale industrial production.

In this specification, the embodiments are mainly described as different from other embodiments, and the same and similar parts in the embodiments may be referred to each other, and different parts in the embodiments may also be used in combination with each other, which is not intended to limit the present invention. The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. An earth leakage protection device, comprising: the device comprises an induction unit, a leakage detection unit, a self-checking protection unit, a rectification unit, a voltage stabilization unit, a voltage clamping unit, a sampling unit, a tripping unit, a first current limiting unit, a second current limiting unit, a first switch unit, a second switch unit and a third switch unit, wherein,

the input end of the voltage stabilizing unit is coupled to the positive output end of the rectifying unit, and the output end of the voltage stabilizing unit is respectively coupled to the electric leakage detecting unit, the voltage clamping unit and the self-detection protecting unit so as to supply power to the electric leakage detecting unit, the voltage clamping unit and the self-detection protecting unit; the negative output end of the rectifying unit is grounded;

the self-test protection unit includes: the first port of the logic decision module is connected with the other end of the electric leakage detection unit; the second port of the logic decision module is connected with the control end of the first switch unit; a third port of the logic decision module is connected with the control end of the second switch unit; a fourth port of the logic decision module is connected with the control end of the third switching unit; a fifth port of the logic decision module is connected with the phase detection module; a sixth port of the logic decision module is connected with one end of the sampling unit to send a high level signal or a low level signal to the sampling unit; the phase detection module is connected with one end of the sampling unit to receive the current potential of the first conducting end of the third switching unit fed back by the sampling unit;

wherein, in a self-test phase, the self-test protection unit is configured to: firstly, the self-checking protection unit controls the first switch unit to be disconnected, and then when the self-checking protection unit detects that the current phase of the external live wire/zero line is in a positive half cycle or a negative half cycle, the self-checking protection unit controls the second switch unit and the third switch unit to be disconnected; then, the self-test protection unit pulls the first conductive end of the third switch unit to a high level state through the sampling unit, then controls the first switch unit to be conducted to simulate a leakage current signal, and if the self-test protection unit receives the leakage current signal sent by the induction unit through the leakage current detection unit, sends a control signal to the control end of the third switch unit to control the third switch unit to be conducted; finally, the current level state of the first conductive end of the third switching unit is obtained through the sampling unit, and at the moment, if the current level state of the first conductive end of the third switching unit is a low level, the analog leakage detection is judged to be passed; if the current level state of the first conductive end of the third switching unit is a high level, judging that the analog leakage detection fails;

in a non-self-checking stage, the control terminal of the second switching unit receives a high-level signal of the rectifying unit through the second current limiting unit and the tripping unit, and at this time, the second switching unit is in a conducting state, and the self-checking protection unit is configured to: the self-checking protection unit controls the first switch unit and the third switch unit to be disconnected, and when the self-checking protection unit receives a leakage current signal sent by the induction unit through the leakage current detection unit, the self-checking protection unit sends a control signal to the third switch unit to control the third switch unit to be switched on, so that the tripping unit is switched to a disconnected state from a conducting state.

2. An earth leakage protection device according to claim 1, wherein said self-test protection unit further comprises: and the alarm module is connected with the logic judgment module, wherein in a self-checking stage, when the simulation leakage detection fails, the phase detection module receives a high-level signal of the first conductive end of the third switch unit through the sampling unit and feeds the high-level signal back to the logic judgment module, and at the moment, the logic judgment module outputs a self-checking fault signal to the alarm module.

3. A residual current device as claimed in claim 2, characterized in that said self-test protection unit further comprises: the alarm time detection module is respectively connected with the alarm module and the logic judgment module and is used for detecting the alarm duration time output by the alarm module; if the current alarm duration time exceeds a preset time threshold value, an overtime signal is sent to the logic decision module.

4. A residual current device according to claim 2, characterized in that said self-test protection unit further comprises: and the execution module is connected with the alarm module and is used for receiving a driving signal output by the alarm module so as to send out a corresponding alarm indication.

5. A leakage protection device according to claim 1, wherein the first switching unit is a triode or a MOS transistor; the second switch unit is a triode or an MOS tube; the third switching unit is a thyristor.

6. A residual current device as claimed in claim 1, characterized in that said residual current device further comprises: and the backflow preventing unit is connected between the positive output end of the rectifying unit and the voltage stabilizing unit in series.

7. An earth leakage protection device as claimed in claim 6, wherein the reverse flow preventing unit comprises: the positive pole of the diode is connected with the positive output end of the rectifying unit, the negative pole of the diode is connected with one end of the current-limiting resistor, the other end of the current-limiting resistor is connected with the input end of the voltage stabilizing unit, the positive pole of the capacitor is connected with the input end of the voltage stabilizing unit, and the negative pole of the capacitor is grounded.

8. A residual current device as claimed in claim 1, characterized in that said trip unit is a trip coil; the induction unit is an induction coil.

9. A residual current device according to claim 1, characterized in that said first current limiting unit and said second current limiting unit are both current limiting resistors.