CN112834950B - Electric leakage detection circuit, electric leakage protection circuit and household appliance - Google Patents
Electric leakage detection circuit, electric leakage protection circuit and household appliance Download PDFInfo
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- CN112834950B CN112834950B CN202010928728.6A CN202010928728A CN112834950B CN 112834950 B CN112834950 B CN 112834950B CN 202010928728 A CN202010928728 A CN 202010928728A CN 112834950 B CN112834950 B CN 112834950B
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- G—PHYSICS
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/145—Indicating the presence of current or voltage
- G01R19/15—Indicating the presence of current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/28—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at two spaced portions of a single system, e.g. at opposite ends of one line, at input and output of apparatus
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Abstract
The invention discloses a leakage detection circuit, a leakage protection circuit and a household appliance, wherein the leakage detection circuit comprises a charged conductor with alternating current and a connecting end for connecting with a detected conductor, the connecting end is connected with a first end of a first coupling capacitor, a second end of the first coupling capacitor is connected with a first end of a fourth coupling capacitor, and a second end of the fourth coupling capacitor is grounded; the live conductor is connected with the first end of the second coupling capacitor, the second end of the second coupling capacitor is connected with the first end of the third coupling capacitor, and the second end of the third coupling capacitor is grounded; and a sampling resistor is connected between the intersection point of the second end of the second coupling capacitor and the first end of the third coupling capacitor and the intersection point of the second end of the first coupling capacitor and the first end of the fourth coupling capacitor. The voltage measuring reference point is respectively connected with the live conductor and the zero line in a double-capacitor mode, so that the detection reference point of the voltage at two ends of the sampling resistor and the reference potential form stronger and more stable coupling, and the detection is stable and reliable.
Description
Technical Field
The invention belongs to the field of household electrical appliance equipment, and particularly relates to a leakage detection circuit, a leakage protection circuit and a household electrical appliance.
Background
The household appliances are released from heavy, trivial and time-consuming household work, create more comfortable and beautiful life and working environment which are more beneficial to physical and mental health for human beings, provide rich and colorful cultural and entertainment conditions, and become necessities of modern family life.
Due to the requirements of installation strength and safety and reliability of part of household appliances, the shell of the household appliance is made of metal. The power supply of domestic appliance all is provided by the forceful electric power, and the forceful electric power is direct to be connected with domestic appliance's power end, if in case the inside equipment of domestic appliance is because insulating ageing, the damaged electric leakage that takes place, when metal casing ground connection became invalid, perhaps did not realize effectual ground connection, when the user touched metal casing, will bring the potential safety hazard for the user. Therefore, the earth leakage detection protection device is usually arranged on the household appliance or the home-to-home power receiving terminal of the user.
In the prior art, reference potential points of a capacitive induction type electricity measuring device, such as a non-contact test pencil, a leakage inductance module in a household appliance, and the like, are generally a circuit board floor, and have no substantial reference potential, and a detection system is poor in anti-interference capability and greatly influenced by the environment because the capacitance to the ground is uncertain. Factors such as whether or not a hand is held have an effect on it.
And the detection circuit is electrified with strong electricity by using a reference point acquisition mode electrically connected with the zero line, so that certain difficulty is caused in the isolation of the strong electricity, and the product is difficult to meet the safety specification.
In view of the above, the present invention is particularly proposed.
Disclosure of Invention
The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a leakage detection circuit, which adds a capacitor structure with coupling characteristics in the leakage detection circuit, so that a detection reference point of a voltage and a reference potential form a strong and stable coupling, and the measurement is stable and reliable.
Another object of the present invention is to provide a leakage protection circuit, which includes the leakage detection circuit.
Another object of the present invention is to provide a household appliance, comprising the above leakage detecting circuit and/or leakage protecting circuit.
In order to solve the technical problems, the invention adopts the technical scheme that:
a leakage detection circuit comprises a live conductor with alternating current and a connecting end used for being connected with a detected conductor, wherein the connecting end is connected with a first end of a first coupling capacitor, a second end of the first coupling capacitor is connected with a first end of a fourth coupling capacitor, and a second end of the fourth coupling capacitor is grounded;
the live conductor is connected with the first end of the second coupling capacitor, the second end of the second coupling capacitor is connected with the first end of the third coupling capacitor, and the second end of the third coupling capacitor is grounded;
and a sampling resistor is connected between the intersection point of the second end of the second coupling capacitor and the first end of the third coupling capacitor and the intersection point of the second end of the first coupling capacitor and the first end of the fourth coupling capacitor.
Furthermore, the second end of the third coupling capacitor is grounded after being connected with a zero line.
Further, the capacitance values of the second coupling capacitor and the third coupling capacitor are equal to or within 20%.
Further, the first coupling capacitor and/or the second coupling capacitor and/or the third coupling capacitor are electronic elements with capacitance characteristics, or capacitors formed by two metal structures close to each other;
the fourth coupling capacitor is a structure with capacitance characteristics, wherein one end pole plate is of a metal structure, and the other end of the fourth coupling capacitor is of the ground.
Furthermore, a voltage dividing resistor is further arranged between the intersection point of the first coupling capacitor and the fourth coupling capacitor and the sampling resistor.
And the voltage acquisition circuit is connected to two ends of the sampling resistor and used for detecting the voltages at two ends of the sampling resistor.
A leakage protection circuit comprising a leakage detection circuit as described above.
And the detection circuit is connected to two ends of the sampling resistor and is used for detecting whether the voltage at the two ends of the sampling resistor is smaller than a set threshold value.
Further, the detection circuit comprises a voltage conditioning circuit, a comparison circuit, a warning circuit and/or a switch circuit; wherein
The voltage conditioning circuit is connected with two ends of the sampling resistor and is used for conditioning the voltages at two ends of the sampling resistor and outputting the conditioned voltages to the comparison circuit;
the comparison circuit is used for comparing the conditioned voltage with the reference voltage of the comparison circuit and outputting the comparison result to the warning circuit and/or the switch circuit;
the warning circuit sends out warning information according to the comparison result; and/or the switch circuit is disconnected or connected according to the comparison result.
A domestic appliance comprising a leakage detection circuit as described above, and/or a leakage protection circuit as described above.
Further, the household appliance is a gas water heater, an electric water heater or a heat pump water heater.
After the technical scheme is adopted, compared with the prior art, the invention has the following beneficial effects.
When the alternating voltage at two ends of the sampling resistor is detected, the pressure measuring reference point is respectively connected with the live conductor and the zero line in a double-capacitor mode, the intersection point of the second coupling capacitor, the third coupling capacitor and the sampling resistor forms the reference point when the voltage at two ends of the sampling resistor is detected by arranging the second coupling capacitor and the third coupling capacitor, and the reference point and the reference potential point form stronger and more stable coupling, so that the reference point of the voltage acquisition circuit becomes a reliable reference, the measurement is stable and reliable, and the condition that the live conductor is leaked but not reported or has no possibility of false alarm is avoided.
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a schematic circuit diagram of a leakage detection circuit according to the present invention;
FIG. 2 is a schematic diagram of a circuit structure of the leakage protection circuit according to the present invention;
FIG. 3 is a functional block diagram of an embodiment of a leakage protection circuit of the present invention;
fig. 4 is a functional block diagram of another embodiment of the earth leakage protection circuit of the present invention;
in the figure: 10. a leakage protection circuit; 101. a leakage detection circuit; 102. a detection circuit; 1021. a voltage conditioning circuit; 1022. a comparison circuit; 1023. a warning circuit; 1024. a switching circuit;
A. a leakage point; B. a conductor under test; c1, a first coupling capacitor; c2, a second coupling capacitor; c3, a third coupling capacitance; c4, a fourth coupling capacitor; l, a live wire; D. an access point; E. a reference point; F. a reference potential point; n, a zero line; r1, a sampling resistor; r2, divider resistance; t, a transformer; G. an electrically charged conductor; H. and a connecting end.
It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred devices or elements must have specific orientations, be constructed in specific orientations, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As shown in fig. 1 to 4, the present invention provides a leakage detecting circuit, a leakage protection circuit and a household appliance.
Fig. 1 is a schematic circuit diagram of the leakage detecting circuit 101. The electric leakage detecting circuit 101 includes a live conductor G with alternating current and a connection terminal H for connecting with a conductor B to be detected.
The connection terminal H is connected to the first terminal of the first coupling capacitor C1, the second terminal of the first coupling capacitor C1 is connected to the first terminal of the fourth coupling capacitor C4, and the second terminal of the fourth coupling capacitor C4 is grounded.
The live conductor G is connected to a first terminal of a second coupling capacitor C2, a second terminal of the second coupling capacitor C2 is connected to a first terminal of a third coupling capacitor C3, and a second terminal of the third coupling capacitor C3 is grounded.
A sampling resistor R1 is connected between the intersection point of the second end of the second coupling capacitor C2 and the first end of the third coupling capacitor C3 and the intersection point of the second end of the first coupling capacitor C1 and the first end of the fourth coupling capacitor C4.
The junction of the second coupling capacitor C2, the third coupling capacitor C3 and the sampling resistor R1 constitutes a reference point E for detecting the voltage across the sampling resistor R1.
The live conductor G has a first state and a second state:
when the voltage at the two ends of the sampling resistor R1 is greater than or equal to a set threshold value, the live conductor G is in a first state, at the moment, no leakage occurs at the leakage point A, the live conductor G is disconnected from the tested conductor B, and then no current flows through the tested conductor B.
When the voltage across the sampling resistor R1 is lower than a set threshold, the live conductor G is in the second state, and at this time, a leakage condition occurs at the leakage point a, the live conductor G is connected to the tested conductor B, and then a current flows through the tested conductor B.
Furthermore, the second end of the third coupling capacitor is grounded after being connected with a zero line.
In detail, as shown in fig. 1, the circuit configuration includes a power system including a ground, a transformer T output winding, a live line L, a live conductor G, and a measured conductor B. The transformer T is a neutral-grounded transformer T, the phase terminal pair of the winding has an ac voltage to earth, and the outgoing line becomes the hot line L. Since the live conductor is connected to the live line, the live conductor has an alternating voltage to earth.
When the tested conductor B is not charged, that is, no leakage occurs at the leakage point a of the live conductor G, the path from the live conductor G to the ground can be seen as: the fourth coupling capacitor C4 is connected in series with the sampling resistor R1, then connected in parallel with the third coupling capacitor C3, and then connected in series with the second coupling capacitor C2. The alternating voltage between the live conductor G and the ground line enables a certain alternating current to pass through the path, and the two ends of the sampling resistor R1 can obtain an alternating voltage with a certain amplitude, for example, equal to or greater than a set threshold value.
When the leakage condition occurs at the leakage point a of the live conductor G, the first end of the first coupling capacitor C1 is also connected to the live conductor G through the connection terminal H, that is, the connection terminal H is charged through the detected conductor B. Thus, one path from live conductor G to earth ground can be seen as: the first coupling capacitor C1 and the fourth coupling capacitor C4 are in a series structure, and the second coupling capacitor C2 and the third coupling capacitor C3 are in a series structure; at this time, the alternating current potential of the junction of the sampling resistor R1 and the first coupling capacitor C1 and the fourth coupling capacitor C4, i.e., the voltage monitoring point, is between the zero line N and the live line L. The potentials at the two ends of the sampling resistor R1, the access point D and the reference point E are relatively balanced, and the amplitude of the alternating voltage is reduced and even is offset to zero. At this time, the ac voltage with amplitude is not applied across the sampling resistor R1 or is lower than the set threshold.
Therefore, whether or not the live conductor G has the leakage point a can be determined based on whether or not the ac voltage obtained by the sampling resistor R1 is lower than a predetermined threshold value.
In the above-described embodiment, whether or not there is leakage is determined by detecting whether or not the ac voltage across the sampling resistor R1 is lower than a predetermined threshold. When the alternating voltage at the two ends of the sampling resistor R1 is detected, in the scheme of the invention, the pressure measuring reference point E is respectively connected with the live conductor G and the zero line N in a double-capacitor mode, and the second coupling capacitor C2 and the third coupling capacitor C3 are arranged, so that when the voltage at the two ends of the sampling resistor R1 is detected, the reference point E and the reference potential point F form stronger and more stable coupling, and the reference point E of the voltage acquisition circuit becomes a reliable reference.
Further, in the above preferred embodiment, when the second end of the third coupling capacitor C3 is connected to the ground after connecting to the zero line, the reference potential point F is located on the zero line, and thus the failure in case of the bad ground is prevented.
The tested conductor B can be the shell of a household appliance or a conductor which should not be electrified but is possibly electrified. For example, when the tested conductor B is the housing of the household appliance and the insulating layer of the live conductor G is damaged, the live conductor G has a leakage point a, so that the tested conductor B, i.e. the housing of the household appliance, is conducted with the live conductor G.
When the conductor B to be tested is conducted with the live conductor G, the first coupling capacitor C1 and the fourth coupling capacitor C4 have the characteristic of "alternating current and direct current", and therefore a loop having a current is formed among the live conductor G, the first coupling capacitor C1, the fourth coupling capacitor C4 and the ground.
At this time, the potentials at both ends of the sampling resistor R1 are relatively balanced, and the voltage detected by connecting a voltmeter to both ends of the sampling resistor R1 is lower than a set threshold or the voltage at both ends of the sampling resistor R1 at this time cannot be detected.
In other words, if the voltage across the sampling resistor R1 detected by the multimeter is lower than the set threshold or the voltage across the sampling resistor R1 cannot be detected, it indicates that the live conductor G has an electric leakage, and the housing of the household appliance may be charged.
On the contrary, if the universal meter is used for detecting the voltages at the two ends of the sampling resistor R1, the voltage is detected, which indicates that the live conductor G has no electric leakage phenomenon and the shell has no electrification, and the risk of electric shock caused by the touch of the user on the shell is very small or almost no risk.
The junction of the sampling resistor R1, the second end of the second coupling capacitor C2, and the first end of the third coupling capacitor C3 is the reference point E when obtaining the voltage across the sampling resistor R1. In the leakage detection circuit 101 of the present invention, when no leakage occurs, a current flows through the sampling resistor R1, and the reference point E is connected to the live conductor G through the second coupling capacitor C2 and to the neutral line N through the third coupling capacitor C3.
Furthermore, a circuit loop combining electric connection and capacitive coupling is completely erected by arranging the first coupling capacitor C1, the second coupling capacitor C2, the third coupling capacitor C3 and the fourth coupling capacitor C4 which have capacitance characteristics, so that the measurement is stable and reliable.
In a preferred embodiment, the capacitance values of the second coupling capacitor C2 and the third coupling capacitor C3 are equal to or within 20%.
In detail, when the second coupling capacitor C2 is equal to or very close to the third coupling capacitor C3, the reverse connection of the live line L and the neutral line N has negligible influence on the reverse connection, and the applicability is very strong.
In a further aspect, the first coupling capacitor C1 and/or the second coupling capacitor C2 and/or the third coupling capacitor C3 are electronic elements with capacitance characteristics, or capacitors formed by two metal structures close to each other.
The fourth coupling capacitor is a structure with capacitance characteristics, wherein one end pole plate is of a metal structure, and the other end of the fourth coupling capacitor is of the ground.
In detail, the first coupling capacitor C1, the second coupling capacitor C2, and the third coupling capacitor C3 function to form a stronger and more stable coupling between two ends of the coupling capacitor.
Therefore, the first coupling capacitor C1, the second coupling capacitor C2, and the third coupling capacitor C3 of the present invention only need to be able to conduct in an ac state.
Preferably, in some embodiments, in order to simplify a circuit structure, electronic elements having a capacitive characteristic may be selected as the first coupling capacitor C1, the second coupling capacitor C2, and the third coupling capacitor C3.
In other embodiments, in order to fully utilize the existing structure of the circuit, the first coupling capacitor C1, the second coupling capacitor C2, and the third coupling capacitor C3 are designed as two metal structures close to each other, and the two metal structures close to each other form a capacitor, so that the capacitor has the characteristic of "alternating current and direct current of the capacitor.
In a further scheme, a voltage dividing resistor R2 is further arranged between the intersection point of the first coupling capacitor C1 and the fourth coupling capacitor C4 and the sampling resistor R1.
In detail, the voltage dividing resistor R2 is arranged to make the voltage value at the two ends of the sampling resistor R1 smaller, so as to facilitate the comparison between the voltage of the sampling resistor R1 and the comparator.
For example, when a transistor conduction voltage is used as the comparison voltage, the required set threshold should be about 0.7 v.
In the above scheme, the voltage dividing resistor R2 is arranged, so that the voltage at two ends of the sampling resistor R1 can be acquired more accurately, the implementation is convenient, and the debugging is also convenient.
In a further scheme, two ends of the sampling resistor R1 are connected to a voltage acquisition circuit for detecting voltages at two ends of the sampling resistor R1.
For example, a voltmeter is connected between both ends of the sampling resistor R1.
Still alternatively, the sampling resistor R1 itself may be configured as a resistor including a large impedance in combination with a display lamp, similar to the test pencil principle, that illuminates when current flows through the resistor and the display lamp.
The invention also provides an electric leakage protection circuit which comprises the electric leakage detection circuit 101 and the detection circuit 102.
As shown in fig. 2, the voltage acquisition circuit uses the detection circuit 102 to amplify and process the voltage across the sampling resistor R1. When the voltage across the sampling resistor R1 falls below a set threshold, a display or alarm signal will be generated by the detection circuit 102.
The voltage across the sampling resistor R1 is obtained by the leakage detection circuit 101, and when the voltage across the sampling resistor R1 is lower than a set threshold, it indicates that a leakage phenomenon occurs, and the leakage protection circuit 10 sends out warning information or directly cuts off the current on the live conductor G. When the voltage across the sampling resistor R1 is equal to or higher than the set threshold, no leakage occurs, and the leakage protection circuit 10 is maintained in a normal state.
In one embodiment, the leakage protection circuit 10 includes a leakage detection circuit 101 and a detection circuit 102. The detection circuit 102 includes a voltage conditioning circuit 1021, a comparison circuit 1022, and an alarm circuit 1023.
The voltage conditioning circuit 1021 is connected to two ends of the sampling resistor R1 in the leakage detection circuit 101, and is configured to condition the voltage across the sampling resistor R1 and output the conditioned voltage to the comparison circuit 1022.
The voltage conditioning circuit 1021 may include one or more of voltage conversion, rectification, filtering, amplification, and the like, and convert the voltage across the sampling resistor R1 into a suitable voltage and output the suitable voltage to the comparison circuit 1022.
The comparison circuit 1022 is configured to compare the conditioned voltage with a reference voltage, and output a comparison result to the warning circuit 1023.
The warning circuit 1023 sends out warning information according to the comparison result.
In detail, since the voltage of the ac mains is 220 v, when the live conductor G leaks, the transformer T is provided, as the ac power is connected to the first coupling capacitor C1 and the fourth coupling capacitor C4, which provide an ac channel for the ac power, so that the potentials at the two ends of the sampling resistor R1 are relatively balanced. Because the voltage amplitude, period, noise and other factors of the voltage cannot be directly used for detection, and the voltage is output after being processed by the conditioning circuit, the voltage conditioning circuit 1021 has the function of performing voltage amplitude conversion, rectification, filtering, amplification and other processing on the voltage at the two ends of the sampling resistor R1, so that the alternating-current voltage at the two ends of the resistor corresponds to a direct-current output voltage with a proper amplitude. Then, the adjusted voltage is outputted to the comparison circuit 1022.
The comparison circuit 1022 is provided with a reference voltage, and the comparison circuit 1022 compares and outputs the output voltage of the conditioning circuit with the reference voltage, so as to judge the amplitude of the voltage at the two ends of the sampling resistor R1. Preferably, the reference voltage is a set threshold. For example, when the voltage across the sampling resistor R1 is greater than a set threshold, that is, the input voltage of the comparison circuit 1022 is greater than the reference voltage of the comparison circuit 1022, the comparison circuit 1022 outputs a high level signal; when the voltage across the sampling resistor R1 is less than the set threshold, i.e., the input voltage of the comparison circuit 1022 is less than the reference voltage of the comparison circuit 1022, the comparison circuit 1022 outputs a low level. The comparison result is output to the alert circuit 1023 regardless of whether it is high or low.
The alert circuit 1023 may be a light alert, an audible alert, or a combination of both. For example, when the warning circuit 1023 receives a high level, the control light or the whistle keeps a non-light emitting state and a non-whistle state, which indicates that no electric leakage occurs, and power can be continuously supplied to the live conductor G, so that the equipment connected with the live conductor G can normally operate. When warning circuit 1023 receives the low level, control light scintillation, warning whistle, explain that electric leakage phenomenon has taken place this moment, suggestion user or operating personnel carry out next step's operation, cut off the power to electrified conductor G power supply.
In another embodiment, the leakage protection circuit 10 includes a leakage detection circuit 101 and a detection circuit 102, wherein the detection circuit 102 includes a voltage conditioning circuit 1021, a comparison circuit 1022, and a switch circuit 1024. The switch circuit 1024 is used to control the conduction and disconnection between the live conductor G and the power supply terminal.
The voltage conditioning circuit 1021 is connected to two ends of the sampling resistor R1 in the leakage detection circuit 101, and is configured to convert the ac voltage at two ends of the sampling resistor R1 into a dc output voltage with an appropriate amplitude, and output the dc output voltage to the comparison circuit 1022.
In detail, the voltage conditioning circuit 1021 may include one or more of voltage conversion, rectification, filtering, amplification, and the like, and convert the voltage across the sampling resistor R1 into a suitable voltage and output the suitable voltage to the comparison circuit 1022.
The comparison circuit 1022 is configured to compare the conditioned voltage with a reference voltage, and output a comparison result to the switch circuit 1024.
The switching circuit 1024 is turned off or on according to the comparison result.
In detail, since the voltage of the ac mains supply is 220 v, when the live conductor G leaks, the transformer T is provided, as if the ac power is connected to the first coupling capacitor C1 and the fourth coupling capacitor C4, the coupling capacitors provide an ac channel for the ac mains supply, so that an ac voltage is generated across the sampling resistor R1. The ac voltage cannot be directly detected due to factors such as voltage amplitude, period, noise, etc., but is output after being processed by the conditioning circuit, and the voltage conditioning circuit 1021 performs voltage amplitude conversion, rectification, filtering, amplification, etc. on the voltage at the two ends of the sampling resistor R1, so that the ac voltage at the two ends of the resistor corresponds to a dc output voltage with a proper amplitude. Then, the adjusted voltage is outputted to the comparison circuit 1022.
The comparison circuit 1022 is provided with a reference voltage, and the comparison circuit 1022 compares and outputs the output voltage of the conditioning circuit with the reference voltage, so as to judge the amplitude of the voltage at the two ends of the sampling resistor R1. For example, when the voltage across the sampling resistor R1 is greater than a set threshold, that is, the input voltage of the comparison circuit 1022 is greater than the reference voltage of the comparison circuit 1022, the comparison circuit 1022 outputs a high level signal; when the voltage across the sampling resistor R1 is less than the set threshold, i.e., the input voltage of the comparison circuit 1022 is less than the reference voltage of the comparison circuit 1022, the comparison circuit 1022 outputs a low level. The comparison result is output to the switching circuit 1024 regardless of whether it is high or low.
For example, when the switching circuit 1024 receives a high level, which indicates that no leakage occurs at this time, the switching circuit 1024 is controlled to be turned on, and power can be continuously supplied to the live conductor G, so that the device connected to the live conductor G operates normally. When the switching circuit 1024 receives a low level, it indicates that a leakage phenomenon occurs at this time, and controls the switching circuit 1024 to turn off to cut off the power supply to the live conductor G.
In the above-mentioned scheme, the voltage conditioning circuit 1021, the comparison circuit 1022, the warning circuit 1023 and the switch circuit 1024 have various implementation forms, and the present invention does not limit the specific structures of the voltage conditioning circuit 1021, the comparison circuit 1022, the warning circuit 1023 and the switch circuit 1024, and any structure capable of implementing the above-mentioned scheme is within the protection scope of the present invention.
In the scheme, the pressure measuring reference point E is respectively connected with the live conductor G and the zero line N in a double-capacitor mode, and the second coupling capacitor C2 and the third coupling capacitor C3 are arranged, so that when the voltage at two ends of the sampling resistor R1 is detected, the reference point E and a reference potential point F of the ground form stronger and more stable coupling, the reference point E of the voltage acquisition circuit becomes a reliable reference, and the situations of electric leakage failure or false leakage failure cannot occur.
In another embodiment, the earth leakage protection circuit 10 may include the warning circuit 1023 and the switch circuit 1024. The specific working process is as described above and will not be described in detail.
The invention also provides a household appliance which comprises the leakage detection circuit 101 and/or the leakage protection circuit 10.
In detail, the leakage detection circuit 101 and/or the leakage protection circuit 10 may be used in a safety detection function module of a household appliance, so as to improve leakage detection efficiency and safety performance of the household appliance.
Further, the household appliance is a gas water heater, an electric water heater or a heat pump water heater.
In detail, the shells of the gas water heater, the electric water heater and the heat pump water heater mostly adopt metal structures, so that the safety performance of the gas water heater, the electric water heater and the heat pump water heater can be greatly improved by adopting the electric leakage detection circuit 101 and/or the electric leakage protection circuit 10.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (11)
1. An electric leakage detection circuit comprises an electrified conductor with alternating current and a connecting end used for being connected with a detected conductor,
the connecting end is connected with the first end of the first coupling capacitor, the second end of the first coupling capacitor is connected with the first end of the fourth coupling capacitor, and the second end of the fourth coupling capacitor is grounded;
the live conductor is connected with the first end of the second coupling capacitor, the second end of the second coupling capacitor is connected with the first end of the third coupling capacitor, and the second end of the third coupling capacitor is grounded;
a sampling resistor is connected between the intersection point of the second end of the second coupling capacitor and the first end of the third coupling capacitor and the intersection point of the second end of the first coupling capacitor and the first end of the fourth coupling capacitor;
when the electrified conductor does not leak electricity, the tested conductor is not electrified, and when the electrified conductor leaks electricity, the tested conductor is electrically connected with the electrified conductor, and then the connecting end is electrically connected with the electrified conductor.
2. The leakage detection circuit according to claim 1,
and the second end of the third coupling capacitor is grounded after being connected with a zero line.
3. The leakage detection circuit according to claim 1,
the capacitance values of the second coupling capacitor and the third coupling capacitor are equal or within 20% of each other.
4. An electrical leakage detection circuit according to claim 2,
the first coupling capacitor and/or the second coupling capacitor and/or the third coupling capacitor are electronic elements with capacitance characteristics, or capacitors formed by two metal structures close to each other;
the fourth coupling capacitor is a structure with capacitance characteristics, wherein one end pole plate is of a metal structure, and the other end of the fourth coupling capacitor is of the ground.
5. The leakage detection circuit according to claim 1,
and a voltage dividing resistor is also arranged between the intersection point of the first coupling capacitor and the fourth coupling capacitor and the sampling resistor.
6. The electrical leakage detection circuit according to any one of claims 1 to 5, further comprising a voltage acquisition circuit connected across the sampling resistor for detecting a voltage across the sampling resistor.
7. An earth leakage protection circuit, characterized by comprising an earth leakage detection circuit according to any one of claims 1-6.
8. The leakage protection circuit of claim 7, further comprising a detection circuit connected across the sampling resistor for detecting whether the voltage across the sampling resistor is less than a set threshold.
9. The earth leakage protection circuit of claim 8, wherein the detection circuit comprises a voltage conditioning circuit, a comparison circuit, an alarm circuit and/or a switching circuit; wherein
The voltage conditioning circuit is connected with two ends of the sampling resistor and is used for conditioning the voltages at two ends of the sampling resistor and outputting the conditioned voltages to the comparison circuit;
the comparison circuit is used for comparing the conditioned voltage with the reference voltage of the comparison circuit and outputting the comparison result to the warning circuit and/or the switch circuit;
the warning circuit sends out warning information according to the comparison result; and/or the switch circuit is disconnected or connected according to the comparison result.
10. A domestic appliance comprising a leakage detection circuit according to any of claims 1 to 6, or a leakage protection circuit according to any of claims 7 to 9.
11. A household appliance according to claim 10,
the household appliance is a gas water heater, an electric water heater or a heat pump water heater.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010928728.6A CN112834950B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
| PCT/CN2020/133033 WO2021212840A1 (en) | 2020-09-07 | 2020-12-01 | Electric leakage detection circuit, electric leakage protection circuit, and household appliance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010928728.6A CN112834950B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
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| Publication Number | Publication Date |
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| CN112834950A CN112834950A (en) | 2021-05-25 |
| CN112834950B true CN112834950B (en) | 2022-01-18 |
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| CN202010928728.6A Active CN112834950B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
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| Country | Link |
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| WO (1) | WO2021212840A1 (en) |
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| CN116106623B (en) * | 2023-04-12 | 2023-08-29 | 浙江恒业电子股份有限公司 | Dual-power calculation single-phase electric energy meter and method for non-isolated sampling alternating current |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN87206361U (en) * | 1987-04-16 | 1988-03-23 | 张世昌 | Monitor for insulation of electric appliances |
| IL109607A (en) * | 1994-05-10 | 1997-04-15 | Hayim Nevo | Grounding fault detection system |
| CN101504429B (en) * | 2009-03-09 | 2014-08-13 | 朱玉光 | Portable on-line measurement instrument for electrician electric bridge drain voltage |
| CN101593962B (en) * | 2009-04-09 | 2011-11-23 | 贾翱东 | Anti-electric shock device for household appliance |
| CN202496158U (en) * | 2011-12-31 | 2012-10-17 | 海尔集团公司 | Household appliance metal casing leakage-proof device |
| JP5871160B2 (en) * | 2012-01-12 | 2016-03-01 | 株式会社デンソー | Earth leakage detector |
| CN103293427B (en) * | 2012-02-27 | 2017-02-22 | 海洋王（东莞）照明科技有限公司 | Electric leakage indicating circuit of electric appliances and electric unit with metal outer shell |
| CN104358700B (en) * | 2014-11-27 | 2016-04-13 | 滨州学院 | A kind of have temperature control and the anti-fan control circuitry touching, leak electricity |
| CN104502678B (en) * | 2014-12-18 | 2017-08-25 | 吴江变压器有限公司 | The method for measuring power transformer voltage ratio |
| WO2019130717A1 (en) * | 2017-12-26 | 2019-07-04 | 株式会社豊田自動織機 | Electricity leak detecting circuit |
| CN208567153U (en) * | 2018-04-04 | 2019-03-01 | 广东格美淇电器有限公司 | Earth wire charged testing device and a kind of electric heater |
| CN111060842B (en) * | 2018-10-16 | 2024-06-21 | 株式会社电装 | Leakage judging system |
| CN109116191A (en) * | 2018-11-02 | 2019-01-01 | 国网山西省电力公司电力科学研究院 | A kind of test of electric cable stoppage higher hamonic wave and detection system |
| CN110196373A (en) * | 2019-06-18 | 2019-09-03 | 周芸 | Three core power outlet electric leakage alarming devices |
-
2020
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| WO2021212840A1 (en) | 2021-10-28 |
| CN112834950A (en) | 2021-05-25 |
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