CN114035110A

CN114035110A - Detection method of zero line grounding, detection circuit and device of zero line grounding

Info

Publication number: CN114035110A
Application number: CN202111298292.8A
Authority: CN
Inventors: 周为; 王建忠; 刘新润; 周宣; 袁卿卿; 曾双喜
Original assignee: Wasion Group Co Ltd
Current assignee: Wasion Group Co Ltd
Priority date: 2021-11-04
Filing date: 2021-11-04
Publication date: 2022-02-11

Abstract

The invention discloses a detection method of zero line grounding, a detection circuit of zero line grounding and a device, wherein the method comprises the following steps: generating an excitation current on the excitation coil; collecting a sampling current signal through a sampling coil, and converting the sampling current signal into a sampling voltage signal; and judging whether the zero line is grounded according to the sampling voltage signal. The invention enhances the electrical isolation of the detection circuit of the zero line grounding.

Description

Detection method of zero line grounding, detection circuit and device of zero line grounding

Technical Field

The present disclosure relates to detection methods and devices, and particularly to a detection circuit and a detection device for zero line grounding.

Background

At present, a TN (twisted nematic) system refers to a low-voltage neutral point of a power distribution network which is directly grounded, and can be divided into: the TN-S system, the neutral line and the protective line of the whole system are separated; the neutral line and the protective line of the whole TN-C system are integrated; in a TN-C-S system, a former part of a protection line of a trunk part of the system is shared with a neutral line, and a latter part is separated. At present, most of residential users are single-phase users, and it is difficult to balance three-phase loads, large and unstable unbalanced currents flow in PEN, and a large number of harmonics generated during the use of household appliances are superimposed on the neutral line N, so that the ground potential of the neutral line is offset. Once open circuit fault occurs to PEN or the PEN line contact resistance is increased, the neutral point potential will be severely deviated, so that the metal shell of the exposed conductive part of the household appliance is electrified, and an electric shock accident is caused. And ground faults are most likely to cause electrical fires. It is therefore well established in the new specifications that the residential supply does not use the TN-C system anymore and that the TN-S system must be used, i.e. the separation of the working neutral (N) and the Protective Earth (PE). The difference between the two is as follows:

working neutral (N): the main line is led out after the neutral point of the transformer is grounded, and other parts are not allowed to be grounded;

and a protective earth wire (PE) which is led out of a main line after the neutral point of the transformer is grounded, and the tail end and the middle of the line are repeatedly grounded according to requirements, and the equipment end is repeatedly grounded.

Although the working zero line (N) on the transformer side is grounded, the zero line voltage to ground tested at the user side end is not zero due to the existence of impedance on the line caused by the long line of the working zero line power supply loop, and taking the zero line live line voltage 220Vac provided by a socket with good grounding on the resident side as an example, the normal live line voltage to ground is close to 220Vac, and the zero line voltage to ground is normal within 0V to 5 Vac.

The current leakage protection equipment principle with leakage protection switch as the main is based on that zero line and live wire current is unbalanced, drives outside circuit breaker and constructs and carry out the break operation safety when guaranteeing the rear end electric leakage, under the circumstances of live wire ground connection, can require live wire electric leakage to protect according to leakage protection switch, under the circumstances that load circuit switched on, the electric leakage on the zero line also can carry out the break protection. When the working zero line is not grounded, for example, in the case that the zero line and the load do not form a conducting loop, the coupling leakage generated when the voltage of the working zero line to the ground is 0V, the voltage is small, or the distributed capacitance of the zero line is very small, in this case, the tiny current generated by the working zero line to the ground is not enough to drive the leakage protection switch for protection (the current standard AC type leakage threshold of the leakage protection switch in China is 30 mA).

In summary, in order to ensure the power consumption and the operation safety of the load end, the user and the power grid in practical application, the grounding of the working zero line is avoided in the wiring process of the power consumption side circuit, so that it is necessary to detect whether the zero line is grounded.

However, in the prior art, there are requirements for detecting and protecting the grounding problem of the zero line (neutral line) in the relevant standards such as "UL 943 ground fault circuit interrupter" and the like for the grounding problem of the zero line. The method mainly and basically adopts a self-oscillation method to detect the electric connection state of a zero line and a grounding loop, and protects grounding and electric leakage through a professional analog chip, and the scheme is protected by patents at present and has low expansibility of digital application; in China, the method for detecting the grounding comprises a signal injection method, a constant current source is generated by adopting a frequency different from the working frequency for excitation, and the detection unit is used for detecting the magnitude of the constant current source to judge whether the current signal loss caused by grounding exists or not, so that the method needs to directly superpose an excitation signal on a working zero line.

Disclosure of Invention

The invention provides a method for detecting zero line grounding, a circuit and a device for detecting the zero line grounding, and aims to solve the problem of poor electrical isolation of a zero line grounding detection circuit.

In order to achieve the above object, the present invention provides a method for detecting zero line grounding, which comprises the following steps:

generating an excitation current on the excitation coil;

collecting a sampling current signal through a sampling coil, and converting the sampling current signal into a sampling voltage signal;

and judging whether the zero line is grounded according to the sampling voltage signal.

Optionally, a sampling value is obtained according to the sampling voltage signal, and if the sampling value is greater than a preset threshold value, the zero line is judged to be grounded;

and if the sampling value is less than or equal to the preset threshold value, judging that the zero line is not grounded.

Optionally, the breaking unit is controlled to disconnect the neutral and live wires from the external load.

In order to achieve the above object, the present application provides a detection circuit for zero-line grounding, including:

the control module provides an excitation signal, receives a sampling voltage signal and judges whether the zero line is grounded according to the sampling voltage signal;

the signal input end of the excitation module is electrically connected with the signal output end of the control module and receives the excitation signal sent by the control module, the excitation module comprises an excitation coil, and an external zero line and an external live wire penetrate through the center of the excitation coil;

the sampling module, the signal output part of sampling module with control module's signal input part electricity is connected, to control module exports sampling voltage signal, sampling module includes the sampling coil, the sampling coil with exciting coil parallel arrangement, zero line and live wire pass the center of sampling coil.

Optionally, the excitation module further includes an amplifying circuit, one end of the amplifying circuit is electrically connected to the control module, and the other end of the amplifying circuit is electrically connected to the excitation coil.

Optionally, the sampling module further includes a filter circuit, a signal input end of the filter circuit is electrically connected to the sampling coil, and a signal output end of the filter circuit is electrically connected to the control module.

Optionally, the detection circuit for zero line grounding further includes a power module, one end of the power module is connected to the control module, and the other end of the power module is connected to the exciting coil.

Optionally, the detection circuit for zero line grounding further includes a communication module, and the communication module is connected with the control module.

Optionally, the detection circuit for neutral grounding further includes a circuit breaking unit, and the circuit breaking unit is electrically connected to the control module.

In order to achieve the above object, the present application further provides a detecting device for zero-line grounding, where the detecting device includes the detecting circuit for zero-line grounding, and the detecting circuit for zero-line grounding includes:

According to the technical scheme, the zero line penetrates through the excitation coil and the sampling coil simultaneously, so that if the zero line is grounded, a conduction loop is formed by a zero line grounding point, the zero line, the ground wire and a far-end zero line grounding point, and the sampling coil can acquire a current signal converted by induced electromotive force on the zero line under the excitation of the excitation coil; if the zero line is not grounded, the induced electromotive force on the zero line cannot be converted into a current signal, and the sampling coil cannot acquire the current signal. Therefore, the control chip can judge whether the zero line is grounded by acquiring enough large-current signals through the sampling coil or not, and the detection of the zero line grounding is finished. The transient electromagnetic induction principle is utilized in the application, so that direct current transmission does not exist before the zero line, the sampling coil and the exciting coil, and the electrical isolation is enhanced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a flow chart of a method for detecting a neutral ground according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of a detection circuit for ground zero line according to an embodiment of the present invention;

FIG. 3 is a schematic circuit diagram of an embodiment of a circuit for detecting a ground fault according to the present invention;

fig. 4 is a schematic circuit structure diagram of another embodiment of the detection circuit for zero line grounding according to the present invention.

The implementation, functional features and advantages of the objectives of the present application will be further explained with reference to the accompanying drawings.

The reference numbers illustrate:

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It should be noted that all the directional indications (such as up, down, left, right, front, and rear … …) in the embodiment of the present application are only used to explain the relative position relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indication is changed accordingly.

In addition, the descriptions referred to as "first", "second", etc. in this application are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit ly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.

In view of the above problem, the present application provides a method for detecting a ground zero line, and referring to fig. 1, in a first embodiment of the method for detecting a ground zero line of the present invention, the method for detecting a ground zero line includes:

step S100, generating an excitation current on an excitation coil;

in this embodiment, the control chip may periodically output an excitation signal to the transistor to control on/off of the transistor, thereby controlling an excitation current flowing through the excitation coil. That is, when the control chip outputs a high level to the transistor, the transistor is in a conducting state, and an excitation current is generated on the excitation coil, and when the control chip outputs a low level to the transistor, the transistor is in a blocking state, and an excitation current is not generated on the excitation coil. Preferably, the sampling chip outputs a half-square wave excitation signal with the frequency of 1khz and the duty ratio of 50%, and the current signal is amplified by the excitation circuit, so that the half-square wave excitation current periodically flows through the excitation coil, and an induced electromotive force is generated on a circuit at the center of the excitation coil due to the fact that the current changing on the excitation coil generates a sudden change magnetic field.

Step S200, collecting a sampling current signal through a sampling coil, and converting the sampling signal into a sampling voltage signal;

in this embodiment, the sampling coil and the exciting coil are arranged in parallel, and the external live wire and the external zero wire simultaneously penetrate through the exciting coil and the sampling coil. Therefore, under the conditions of no electric leakage and no grounding of the zero line, the current on the zero line and the current on the live line collected by the sampling coil are in a balanced state, and therefore the sampling current signal which can be collected by the sampling coil is 0 or smaller; if the zero line is grounded, the zero line and the ground form a conducting loop, current signals are generated on the zero line under the action of induced electromotive force generated by the exciting coil, the current signals can be acquired by the sampling coil to form sampling current signals on the sampling coil, and after the sampling current signals are acquired, the sampling current signals can be converted into sampling voltage signals which can be received by the control chip through the third resistor.

And step S300, judging whether the zero line is grounded according to the sampling voltage signal.

In the embodiment, the zero line simultaneously penetrates through the excitation coil and the sampling coil, so that if the zero line is grounded, the sampling coil can acquire a current signal converted by induced electromotive force on the zero line under the excitation of the excitation coil; if the zero line is not grounded, the induced electromotive force on the zero line cannot be converted into a current signal, and the sampling coil cannot acquire the current signal. Therefore, the control chip can judge whether the zero line is grounded by acquiring enough large-current signals through the sampling coil or not, and the detection of the zero line grounding is finished.

In an embodiment, the step of determining whether the neutral line is grounded according to the sampling signal includes:

acquiring a sampling value according to a sampling voltage signal, and if the sampling value is greater than a preset threshold value, judging that the zero line is grounded;

In this embodiment, after the control chip acquires the sampling voltage signal, a sampling value is calculated according to the sampling voltage signal, and whether the zero line is grounded is determined according to the sampling value. Specifically, if the zero line is grounded, the sampling current signal is large; if the zero line is not grounded, the sampling current signal is smaller or 0. And the sampling value is set to be positively correlated with the sampling current signal, so that if the sampling value is greater than a preset threshold value, the zero line is judged to be grounded, and if the sampling value is less than or equal to the preset threshold value, the zero line is judged to be ungrounded. The preset threshold value is set by a person skilled in the art according to a calculation mode of a sampling value and the ground resistance of the zero line, and can be adjusted in real time. In one embodiment, the sampling frequency of the control chip is 2Mhz, data is provided at a rate of 7.2kSPS (kilosamples per second), the control chip selects 288 data points to be collected, and the sampled current signal is smoothed by the following calculation to obtain a sampled value:

wherein, I is a sampling value, N is the sampling times, I (N) is a sampling current signal, and N is the total sampling times. And if the sampling value I is larger than the preset threshold value, judging that the zero line is grounded, and if the sampling value I is smaller than or equal to the preset threshold value, judging that the zero line is not grounded.

In an embodiment, the step of determining that the neutral line is grounded if the sampling signal is greater than a preset signal threshold includes:

and controlling the circuit breaking unit to break the connection between the zero line and the external load.

In this embodiment, if the control chip determines that the zero line is grounded, the control chip controls the disconnection unit to disconnect the connection between the zero line and the external load, so as to avoid long-time zero line grounding.

As shown in fig. 2, the present invention further provides a detection circuit for zero line grounding, where the detection circuit for zero line grounding includes:

the control module 110 is used for providing an excitation signal, receiving a sampling voltage signal and judging whether the zero line is grounded according to the sampling voltage signal;

a signal input end of the excitation module 120 is electrically connected with a signal output end of the control module 110, and receives the excitation signal sent by the control module 110, the excitation module 120 includes an excitation coil L1, and an external neutral wire and a live wire pass through the center of the excitation coil L1;

the sampling module 130, the signal output part of the sampling module 130 with the signal input part of the control module 110 is electrically connected, to the control module 110 outputs the sampling voltage signal, the sampling module 130 includes a sampling coil L2, the sampling coil L2 with the exciting coil L1 is arranged in parallel, the zero line and the live wire pass through the center of the sampling coil L2.

In this embodiment, the signal output end of the control module 110 is electrically connected to the excitation module 120, and outputs an excitation signal to the excitation module 120; the signal input end of the control module 110 is electrically connected to the sampling module 130, and receives the sampling signal input by the sampling module 130, and because the sampling signal is an analog signal, the control module 110 further includes an analog-to-digital converter, which can convert the sampling signal into a digital sampling signal in the form of a digital signal. Specifically, the control module 110 is a control chip, and preferably, the control chip is an RN8211B chip. The control chip outputs a periodic PWM excitation signal to the excitation module 120 to form a half square wave, preferably, the PWM excitation signal has a frequency of 1KHz, a duty ratio of 50%, and a positive amplitude. In addition, the control chip can also judge whether the zero line is grounded according to the received sampling signal.

In this embodiment, a signal input end of the excitation module 120 is electrically connected to a signal output end of the control module 110, and the excitation module 120 includes an amplifying circuit 121 and an excitation coil L1, wherein the excitation coil L1 uses ferrite as a magnetic core. Preferably, the core winding has 200 turns and the internal resistance is 7 Ω. The amplifier circuit 121 amplifies the excitation signal provided by the control module 110, and generates a periodic half square wave current in the excitation coil L1. Specifically, since a periodically abrupt current passes through the excitation coil L1 and since an external zero line passes through the excitation coil L1, the magnetic field generated by the half-square wave current of the excitation coil L1 on the coil and the magnetic flux on the excitation coil L1 are changed, and thus an electromotive force is induced on the zero line passing through the center thereof. In the embodiment, the zero line and the live line are arranged in an isolated mode and simultaneously pass through the central positions of the sampling coil L2 and the excitation coil L1, under the condition of no electric leakage, if the zero line is grounded, the current balance between the live line and the zero line is broken, the induced electromotive force on the zero line generated by the excitation coil L1 under the action of the excitation current can generate a current signal on a ground loop of the zero line, and the magnitude of the current signal is in direct proportion to the induced electromotive force; if the zero line is not grounded, the current on the live line and the zero line is in a balanced state because the effective conducting loop cannot be formed by the zero line to the ground and then to the far-end neutral line grounding point, and therefore the sampling coil L2 cannot acquire an effective current signal on the zero line.

In this embodiment, a signal output end of the sampling module 130 is electrically connected to a signal input end of the control module 110, and the sampling module 130 outputs a sampling voltage signal to the control module 110. The sampling module 130 includes a sampling coil L2, and the sampling coil L2 is disposed parallel to the excitation coil L1, and it should be noted that the distance between the sampling coil L2 and the excitation coil L1 is not limited, but an external live line and a zero line need to pass through the center of the excitation coil L1. The sampling coil L2 uses permalloy as a magnetic core. Preferably, the core winding has 1000 turns and an internal resistance of 40 Ω. Under the condition that no electric leakage exists and the zero line is grounded, the zero line and the ground form a current loop, a current signal generated in the zero line can be acquired by a sampling coil L2, and the acquired current signal is a sampling current signal; in the case where the zero line is not grounded, an effective conduction loop cannot be formed in the zero line, and therefore a sampling current signal that can be acquired by the sampling coil L2 cannot be generated. In addition, after the sampling coil L2 collects the sampling current signal, the sampling current signal is converted into a sampling voltage signal and then input into the control module 110, and the control module 110 can determine whether the zero line is grounded according to the sampling voltage signal.

Specifically, since the zero line passes through the excitation coil L1 and the sampling coil L2 at the same time, if the zero line is grounded, the sampling coil L2 can acquire a current signal converted by induced electromotive force on the zero line under the excitation of the excitation coil L1; if the zero line is not grounded, the induced electromotive force on the zero line cannot be converted into a valid current signal, and at this time, the sampling coil L2 cannot acquire a sampling current signal. Therefore, the control chip can judge whether the zero line is grounded through whether the sampling coil L2 can acquire a sampling current signal or not, and accordingly detection of zero line grounding is completed.

Furthermore, the excitation module further comprises an amplifying circuit, one end of the amplifying circuit is electrically connected with the control module, and the other end of the amplifying circuit is electrically connected with the excitation coil.

In this embodiment, the excitation module 120 includes an amplifying circuit 121 and an excitation coil L1, one end of a signal of the amplifying circuit 121 is electrically connected to a signal output end of the control module 110, and the other end of the amplifying circuit 121 is electrically connected to the excitation coil L1, because the control module 110 is a control chip, an excitation signal that can be provided by the control chip is often small, and a current that is enough to be collected by the sampling coil L2 is difficult to be excited by an excessively small excitation signal on an external zero line, it is necessary to amplify the excitation signal provided by the control module 110 through the amplifying circuit 121, and then a sufficiently large excitation current that changes periodically is generated on the excitation coil L1.

Further, as shown in fig. 3, in an embodiment, the amplifying circuit 121 includes: the circuit comprises a first resistor R1, a second resistor R2 and a first triode Q1; a first end of the first resistor R1 is electrically connected to the control module 110, a second end of the first resistor R1 is electrically connected to a base of the first transistor Q1, a collector of the first transistor Q1 is electrically connected to a first end of the second resistor R2, a second end of the second resistor R2 is electrically connected to the exciting coil L1, and an emitter of the first transistor Q1 is grounded.

In this embodiment, the amplifying circuit 121 includes a first resistor R1, a second resistor R2, and a first transistor Q1. The first resistor R1 and the second resistor R2 both play a role in limiting current, and specifically, the first resistor R1 is disposed between the control chip and the base of the first triode Q1, and is used for inputting a small signal current to the base of the first triode Q1, so as to ensure that the first triode Q1 is in an amplification region; the second resistor R2 is disposed between the collector of the first transistor Q1 and the winding pin of the excitation coil L1, and is used for limiting the current flowing through the excitation coil L1 and protecting the excitation coil L1. In addition, the emitter of the first transistor Q1 is connected to signal ground. That is, the control chip periodically outputs a driving signal to the first transistor Q1 to control the on/off of the first transistor Q1, so as to control the driving current flowing through the driving coil L1. That is, when the control chip outputs a high level to the first transistor Q1, the first transistor Q1 is turned on, and an excitation current is generated in the excitation coil L1, and when the control chip outputs a low level to the first transistor Q1, the first transistor Q1 is turned off, and no excitation current is generated in the excitation coil L1. Preferably, the first resistor R1 has a resistance of 510 Ω, the second resistor R2 has a resistance of 51 Ω, and the first transistor Q1 is LMBT 4401.

Furthermore, the sampling module further comprises a filter circuit, a signal input end of the filter circuit is electrically connected with the sampling coil, and a signal output end of the filter circuit is electrically connected with the control module.

In this embodiment, the sampling module 130 includes a sampling coil L2 and a filter circuit 131, a signal input end of the filter circuit 131 is electrically connected to the sampling coil L2, and a signal output end of the filter circuit 131 is electrically connected to the control module 110. Specifically, after the sampling module 130 acquires the sampling current signal, the sampling current signal is input to the filter circuit 131, the filter circuit 131 converts the sampling current signal into a sampling voltage signal, and then the filtered sampling voltage signal is transmitted to the control chip after filtering the signal of the incoherent band frequency in the sampling voltage signal. Through the filter circuit 131, anti-aliasing filtering is realized, and the sampling of the sampling voltage signal by the control chip is optimized.

Further, as shown in fig. 4, in an embodiment, the filter circuit 131 includes a third resistor R3, two ends of the third resistor R3 are electrically connected to two ends of the sampling coil L2, a node between a first end of the sampling coil L2 and a first end of the third resistor R3 is a first node, a node between a second end of the sampling coil L2 and a second end of the third resistor R3 is a second node, the first node is electrically connected to the first signal input terminal of the control module 110, and the second node is electrically connected to the second signal input terminal of the control module 110.

In this embodiment, the filter circuit 131 includes a third resistor R3, and two ends of the third resistor R3 are electrically connected to two ends of the sampling coil L2, respectively. Preferably, the resistance of the third resistor R3 is 200 Ω, and since the signal sampled by the sampling coil L2 is a current signal, the third resistor R3 can convert the sampled current signal into a sampled voltage signal, and the sampled voltage signal is filtered and then input into the control chip to be used as a basis for determining whether the zero line is grounded.

Further, the filter circuit 131 further includes: a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2, wherein a first end of the fourth resistor R4 is electrically connected to the first node, and a second end of the fourth resistor R4 is electrically connected to the first signal input end of the control module 110; a first terminal of the fifth resistor R5 is electrically connected to the second node, and a second terminal of the fifth resistor R5 is electrically connected to a second signal input terminal of the control module 110; a first end of the first capacitor C1 is electrically connected to the node between the fourth resistor R4 and the first signal input end of the control module 110, and a second end of the first capacitor C1 is grounded; a first terminal of the second capacitor C2 is electrically connected to the node between the fifth resistor R5 and the second signal input terminal of the control module 110, and a second terminal of the second capacitor C2 is grounded.

In this embodiment, the filter circuit 131 further includes a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a second capacitor C2. A junction of the first terminal of the sampling coil L2 and the first terminal of the third resistor R3 may be set as a first junction, and a junction of the second terminal of the sampling coil L2 and the second terminal of the third resistor R3 may be set as a second junction; a fourth resistor R4 is disposed between the first node and the first signal input of the control module 110, and a fifth resistor R5 is disposed between the second node and the second signal input of the control module 110; the control chip acquires a first sampling voltage signal through the first signal input end and acquires a second sampling voltage signal through the second signal input end. The fourth resistor R4, the fifth resistor R5, the first capacitor C1 and the second capacitor C2 collectively function as anti-aliasing filtering. After the sampled current signal passes through the filter circuit 131, two fully differential voltage signals are obtained and input to the control chip. Preferably, the fourth resistor R4 has a resistance of 1k Ω, and the first capacitor C1 and the second capacitor C2 have a capacitance of 33 nF.

Furthermore, the detection circuit for zero line grounding further comprises a power module, wherein one end of the power module is connected with the control module, and the other end of the power module is connected with the exciting coil. The power module 140 provides an operating voltage to the control module 110 and provides an excitation voltage to the excitation circuit, so that an excitation current is generated on the excitation coil L1.

Furthermore, the detection circuit for zero line grounding further comprises a communication module, and the communication module is connected with the control module.

In this embodiment, the detection circuit for the ground connection of the zero line further includes a communication module 150, the communication module 150 is electrically connected to the control module 110, and after the control chip determines that the zero line is grounded, the communication module 150 sends the information of the ground connection of the zero line to the communication module 150, and reports the information to the user through the communication module 150. In addition, the detection circuit of the zero line grounding further comprises an LED indicator lamp 170, the LED indicator lamp 170 is electrically connected with the control module 110, and the state of the zero line grounding is represented by the state of the LED indicator lamp 170.

Furthermore, the detection circuit for zero line grounding further comprises a circuit breaking unit, and the circuit breaking unit is electrically connected with the control module.

In this embodiment, the circuit for detecting the grounding of the neutral line further includes a circuit breaking unit 160, the circuit breaking unit 160 is disposed at two ends of the load electrically connected to the neutral line and the live line, and is electrically connected to the control module 110, and after the circuit breaking unit 160 is disconnected, the electrical connection between the load and the neutral line and the live line can be disconnected. After the control module 110 detects the neutral-grounded condition, the breaking unit 160 may be controlled to open, thereby protecting the load.

In addition, the present application further provides a detection apparatus for zero line grounding, where the detection apparatus includes the detection circuit for zero line grounding described above, and it can be understood that, because the detection circuit for zero line grounding is used in the detection apparatus, an embodiment of the detection apparatus includes all technical solutions of all embodiments of the detection circuit for zero line grounding described above, and the achieved technical effects are also completely the same, and are not described herein again.

The above description is only a preferred embodiment of the present application, and not intended to limit the scope of the present application, and all modifications and equivalents of the subject matter of the present application, which is intended to be covered by the claims and their equivalents, or which are directly or indirectly applicable to other related arts are intended to be included within the scope of the present application.

Claims

1. A detection circuit for neutral grounding, comprising:

2. The circuit for detecting ground zero of claim 1, wherein said excitation module further comprises an amplification circuit, one end of said amplification circuit being electrically connected to said control module, the other end of said amplification circuit being electrically connected to said excitation coil.

3. The circuit for detecting ground zero of claim 1, wherein the sampling module further comprises a filter circuit, a signal input terminal of the filter circuit is electrically connected to the sampling coil, and a signal output terminal of the filter circuit is electrically connected to the control module.

4. The circuit for detecting ground zero of claim 1, further comprising a power module, wherein one end of said power module is connected to said control module and the other end is connected to said excitation coil.

5. The circuit for detecting neutral grounding of claim 1 wherein said circuit for detecting neutral grounding further comprises a communication module, said communication module being connected to said control module.

6. The circuit for detecting neutral grounding of claim 1, wherein said circuit for detecting neutral grounding further comprises a circuit interrupting unit, said circuit interrupting unit being electrically connected to said control module.

7. A detection method of zero line grounding is characterized in that the detection method of zero line grounding is applied to a detection circuit of zero line grounding, the detection circuit of zero line grounding comprises an exciting coil, a sampling coil and a control module, and the method comprises the following steps:

generating an excitation current on the excitation coil;

8. The method of claim 7, wherein the step of determining whether the neutral wire is grounded based on the sampled voltage signal comprises:

9. The method of claim 8, wherein the step of determining that the neutral is grounded comprises, after the step of determining that the neutral is grounded if the sampled value is greater than a predetermined threshold:

and controlling the disconnection unit to disconnect the connection between the zero line and the live line and the external load.

10. A device for detecting neutral grounding, characterized in that said device comprises a circuit for detecting neutral grounding according to claims 1-6.