CN112834951A - 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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- CN112834951A CN112834951A CN202010929665.6A CN202010929665A CN112834951A CN 112834951 A CN112834951 A CN 112834951A CN 202010929665 A CN202010929665 A CN 202010929665A CN 112834951 A CN112834951 A CN 112834951A
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- H02H3/32—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 corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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- General Physics & Mathematics (AREA)
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses an electric leakage detection circuit, an electric leakage protection circuit and a household appliance, wherein the electric leakage detection circuit comprises a live conductor with alternating current and a connecting end used for being connected with a detected conductor, and the connecting end is connected with a voltage detection circuit; the voltage detection circuit comprises a first coupling capacitor, a sampling resistor and a second coupling capacitor which are sequentially connected; the first coupling capacitor is connected with the tested conductor, and the second coupling capacitor is grounded. According to the invention, the capacitance structure with the coupling characteristic is added in the leakage detection circuit, 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 measurement 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 voltage detection circuit; the voltage detection circuit comprises a first coupling capacitor, a sampling resistor and a second coupling capacitor which are sequentially connected;
the first coupling capacitor is connected with the tested conductor, and the second coupling capacitor is grounded.
Furthermore, a voltage dividing resistor is further arranged between the first coupling capacitor and the sampling resistor.
Preferably, the first coupling capacitor and/or the second coupling capacitor are electronic components having a capacitance characteristic, or capacitors formed by two metal structures close to each other.
And the voltage acquisition circuit is connected to the two ends of the sampling resistor and is used for detecting the voltages at the two ends of the sampling resistor.
Further, the live conductor has a first state and a second state,
when the voltage at two ends of the sampling resistor is lower than a set threshold value, the electrified conductor is in a first state, and at the moment, the electrified conductor does not leak electricity;
when the voltage at the two ends of the sampling resistor is larger than or equal to a set threshold value, the electrified conductor is in a second state, and at the moment, the electrified conductor leaks electricity.
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 greater than a set threshold value or not.
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 household 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.
The scheme adopted by the invention is that a zero line or a ground wire is used as a reference potential, a second coupling capacitor with coupling characteristics is arranged, and a reference point on a circuit is coupled with an alternating current zero line by using a capacitor structure, so that when the voltage at two ends of a sampling resistor is detected, the reference point and the reference potential form stronger and more stable coupling, the reference point of a voltage acquisition circuit becomes a reliable reference, the measurement is stable and reliable, and the condition that a charged 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; 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 detection circuit 101 comprises a live conductor G with alternating current, a connection end H is arranged on the detected conductor B, and the connection end H is connected with a voltage detection circuit; the voltage detection circuit comprises a first coupling capacitor C1, a sampling resistor R1 and a second coupling capacitor C2 which are connected in sequence; the first coupling capacitor C1 is connected with the tested conductor B, and the second coupling capacitor C2 is grounded.
The junction of the sampling resistor R1 and the second coupling capacitor C2 forms a reference point E for detecting the voltage at two ends of 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 smaller than a set threshold, the live conductor G is in the first state, at the moment, the live conductor G does not leak electricity, and the live conductor G is disconnected from the tested conductor B equivalently; when the voltage across the sampling resistor R1 is greater than or equal to a predetermined threshold value, and the live conductor G is in the second state, the live conductor G leaks current, which is equivalent to the live conductor G being connected to the tested conductor B.
In detail, as shown in fig. 1, the circuit structure includes a power system, and the power system includes a ground, a transformer T output winding, a live conductor L, a live conductor G, and a measured conductor B. The transformer T is a neutral-grounded transformer, and the phase terminal pair of the winding has an ac voltage to ground, and the outgoing line becomes the hot line L. The live conductor is connected to the live line, and therefore, the live conductor has an alternating voltage to earth.
When the live conductor G does not leak, the voltage across the sampling resistor R1 in the voltage detection circuit is smaller than the set threshold, and at this time, the live conductor G and the detected conductor B are in the first state, that is, the live conductor G and the detected conductor B are disconnected, so that no current flows through the voltage detection circuit connected to the connection terminal H and the detected conductor B, or the current is very small.
When the live conductor G leaks electricity, the live conductor G and the detected conductor B are connected at the leakage point a, and at this time, the live conductor G and the detected conductor B are connected, so that the current in the live conductor G flows through the voltage detection circuit through the connection end H, a loop is formed between the current and the ground, and a potential difference exists between the access point D of the sampling resistor R1 in the voltage detection circuit and the reference point E, that is, the voltage at two ends of the sampling resistor R1 is greater than or equal to a set threshold value. In this case, it means that the current also flows through the conductor B to be measured.
Therefore, whether the leakage point exists in the electrified conductor G can be determined according to whether the alternating voltage acquired by the sampling resistor is higher than a certain set threshold value.
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 voltage detection circuit is electrically connected to the live conductor G, the first coupling capacitor C1 and the second coupling capacitor C2 have a characteristic of "alternating current and direct current", and therefore a loop having a current is formed between the live conductor G, the voltage detection circuit, and the ground.
At this time, the voltage across the sampling resistor R1 can be detected by connecting a voltmeter to the ends of the sampling resistor R1, where the voltage across the sampling resistor R1 has a constant voltage. For example, when a multimeter is used to detect the voltage across the sampling resistor R1, and two terminals of the multimeter are connected to two ends of the sampling resistor R1, respectively, the multimeter will display the value of the specific voltage across the sampling resistor R1 at that time.
In other words, if a multimeter is used to detect that the voltage is present across the sampling resistor R1, it indicates that the live conductor G is leaking current, and the housing of the household appliance may be live, and if the housing is touched, there is a risk of electric shock.
On the contrary, if the universal meter is adopted to detect the voltages at the two ends of the sampling resistor R1, the voltage is not detected, which indicates that no leakage phenomenon occurs in the electric conduction, the shell is not electrified, and the risk of electric shock when a user touches the shell is very small and almost zero.
In the leakage detecting circuit 101 of the present invention, when leakage occurs, one end of the voltage detecting circuit is connected to the live conductor G, and the other end is grounded. The junction of the sampling resistor R1 and the second coupling capacitor C2 is the reference point E when the voltage across the sampling resistor R1 is obtained.
In the process, the scheme adopted by the invention is that the ground is used as a reference potential point, and the second coupling capacitor C2 is arranged, so that when the voltage at two ends of the sampling resistor R1 is detected, the reference point E and the reference potential point form stronger and more stable coupling, and the reference point E of the voltage acquisition circuit becomes a reliable reference.
Furthermore, by arranging the second coupling capacitor C2, a circuit loop combining electric connection and capacitive coupling is completely erected, so that the measurement is stable and reliable.
In a further scheme, a voltage dividing resistor R2 is further disposed between the first coupling capacitor C1 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 aspect, the second coupling capacitor C2 may be an electronic component with a capacitive characteristic, or a capacitor formed by two metal structures close to each other.
In detail, the second coupling capacitor C2 is used to form a stronger and more stable coupling between the two ends of the second coupling capacitor C2, i.e., the reference point E and the reference potential point F.
Therefore, the second coupling capacitor C2 of the present invention only needs to be able to conduct the reference point E and the reference potential point F in an ac state.
Preferably, in some embodiments, in order to simplify the circuit structure, an electronic component having a capacitive characteristic may be selected as the second coupling capacitor C2.
In other embodiments, in order to fully utilize the existing structure of the circuit, the second coupling capacitor C2 is designed as two metal structures close to each other, so that the two metal structures close to each other form a capacitor, and the capacitor has the characteristic of "alternating current and direct current".
In a further aspect, the first coupling capacitor C1 is an electronic component with a capacitive characteristic, or a capacitor formed by two metal structures close to each other.
In detail, the first coupling capacitor C1 functions to form a stronger and more stable coupling between two ends of the first coupling capacitor C1.
Therefore, the first coupling capacitor C1 of the present invention only needs to be able to conduct in an ac state.
Preferably, in some embodiments, in order to simplify the circuit structure, an electronic component having a capacitive characteristic may be selected as the first coupling capacitor C1.
In other embodiments, in order to fully utilize the existing structure of the circuit, the first coupling capacitor C1 is designed as two metal structures close to each other, so that the two metal structures close to each other form a capacitor, and the capacitor has the characteristic of "alternating current and direct current".
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 to include a combination of a high impedance resistor and an indicator light, similar to the test pencil principle, that illuminates when the voltage across the indicator light reaches a certain value.
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 a sufficiently large ac voltage is present across the sampling resistor R1, a display or alarm signal will be generated by the detection circuit 102.
The leakage detection circuit 101 obtains the voltage across the sampling resistor R1, and when the voltage across the sampling resistor R1 is lower than a set threshold, no leakage occurs, and the leakage protection circuit 10 is maintained in a normal state. When the voltage across the sampling resistor R1 is greater than or equal to the set threshold, indicating that an electrical leakage has occurred, the electrical leakage protection circuit 10 sends out a warning message or directly cuts off the power supply source of the live conductor G.
Note that the sensitivity of the leakage detection circuit 101 can be adjusted by adjusting the magnitude of the set threshold. The sensitivity is low, and the current flowing through the human body is too large, so that the leakage protection effect cannot be realized; the sensitivity is too high, which causes the leakage protector to malfunction due to normal tiny leakage of the circuit or the electrical equipment, and the power supply is cut off, so the leakage protector needs to be adjusted to the most appropriate value.
For example, when the leakage protection requirement is high, the set threshold value may be set to a small value, and the sensitivity of leakage detection is high, so that the leakage protection requirement can be satisfied. When the requirement for leakage protection is slightly low, the set threshold value can be set to be a relatively large value, so that the sensitivity of leakage detection is relatively low, and misoperation caused by small leakage can be avoided.
As shown in fig. 3, in one 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 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 in the comparison circuit 1022, 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 commercial power of 220 v is introduced to the live line L, when the live conductor G leaks, the transformer T is provided, as if the ac power is connected to the leakage detecting circuit, and the coupling capacitor provides an ac channel for the leakage detecting circuit, so that an ac voltage is generated across the sampling resistor R1. 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, a sound alert, or a combination of both. For example, when the warning circuit 1023 receives a high level, it controls the light to flash and the warning whistle to indicate that a current leakage occurs, and prompts the user or the operator to perform the next operation to cut off the power supply to the live conductor G. When warning circuit 1023 receives the low level, control light or whistle and keep the state of not giving out light, not whistling, show that the electric leakage phenomenon does not take place this moment, can continue to supply power to electrified conductor G, make the equipment normal operating of being connected with electrified conductor G.
As shown in fig. 4, 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 to 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 introduced to the live conductor G is 220 v ac mains, when the live conductor G leaks, the live conductor G further includes a transformer T, which is connected to the leakage detection circuit, and the coupling capacitor provides an ac channel for the leakage detection circuit, 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, 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. When the switch circuit 1024 receives a low level, it indicates that no leakage occurs, and the switch circuit 1024 is controlled to be turned on, so that power can be continuously supplied to the live conductor G, and the device connected to the live conductor G can normally operate.
In the above-mentioned scheme, the voltage conditioning circuit 1021, the comparing 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 warning circuit 1023 and the switch circuit 1024, and any structure capable of implementing the above-mentioned scheme of the present invention is within the protection scope of the present invention.
In the above scheme, the leakage detection circuit 101 with the second coupling capacitor C2 is adopted to form a strong and stable coupling between the detection reference point E and the reference potential point F, so that the detection reference point E becomes a reliable reference, the measurement is stable and reliable, and the leakage or the false alarm is not caused.
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 and/or the electric leakage protection circuit.
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 (10)
1. 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 voltage detection circuit; it is characterized in that the preparation method is characterized in that,
the voltage detection circuit comprises a first coupling capacitor, a sampling resistor and a second coupling capacitor which are sequentially connected;
the first coupling capacitor is connected with the tested conductor, and the second coupling capacitor is grounded.
2. The leakage detection circuit according to claim 1,
and a voltage dividing resistor is also arranged between the first coupling capacitor and the sampling resistor.
3. An electric leakage detection circuit according to claim 1 or 2,
the first coupling capacitor and/or the second coupling capacitor are electronic elements with capacitance characteristics, or capacitors formed by two metal structures close to each other.
4. The electrical leakage detection circuit according to any one of claims 1 to 3, further comprising a voltage acquisition circuit connected across the sampling resistor for detecting a voltage across the sampling resistor.
5. An electric leakage detection circuit according to any one of claims 1 to 3,
the live conductor has a first state and a second state,
when the voltage at two ends of the sampling resistor is lower than a set threshold value, the electrified conductor is in a first state, and at the moment, the electrified conductor does not leak electricity;
when the voltage at the two ends of the sampling resistor is larger than or equal to a set threshold value, the electrified conductor is in a second state, and at the moment, the electrified conductor leaks electricity.
6. An earth leakage protection circuit, characterized by comprising an earth leakage detection circuit according to any one of claims 1-5.
7. The leakage protection circuit of claim 6, further comprising a detection circuit connected across the sampling resistor for detecting whether the voltage across the sampling resistor is greater than a set threshold.
8. The earth leakage protection circuit of claim 7, 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.
9. An electric household appliance comprising an earth leakage detection circuit according to any of claims 1-5 and/or an earth leakage protection circuit according to any of claims 6-8.
10. A household appliance according to claim 9,
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 |
|---|---|---|---|
| CN202010929665.6A CN112834951B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
| PCT/CN2020/133032 WO2021212839A1 (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 |
|---|---|---|---|
| CN202010929665.6A CN112834951B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112834951A true CN112834951A (en) | 2021-05-25 |
| CN112834951B CN112834951B (en) | 2023-04-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010929665.6A Active CN112834951B (en) | 2020-09-07 | 2020-09-07 | Electric leakage detection circuit, electric leakage protection circuit and household appliance |
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| WO (1) | WO2021212839A1 (en) |
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| WO2021212839A1 (en) | 2021-10-28 |
| CN112834951B (en) | 2023-04-14 |
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