CN210401618U

CN210401618U - Circuit for detecting electric leakage through electric leakage voltage

Info

Publication number: CN210401618U
Application number: CN201921321796.5U
Authority: CN
Inventors: 郭长宝; 林清武; 马善林; 宗立杰
Original assignee: Shandong Lingbao Intelligent Technology Co Ltd
Current assignee: Shandong Lingbao Intelligent Technology Co Ltd
Priority date: 2019-08-15
Filing date: 2019-08-15
Publication date: 2020-04-24
Anticipated expiration: 2029-08-15

Abstract

The embodiment of the utility model discloses circuit through leakage voltage detection electric leakage, detection circuitry includes opto-coupler isolation circuit, pulse filter circuit, analog amplification circuit and trigger release circuit, opto-coupler isolation circuit is used for converting leakage voltage into electric leakage pulse signal, pulse filter circuit is used for filtering electric leakage pulse signal, analog amplification circuit is used for carrying out the amplitude to the signal after the filtering and takes care of, trigger release circuit is used for converting the signal after the amplitude is taken care of into LEVEL signal LEVEL _ OUTPUT, and latch or release LEVEL signal LEVEL _ OUTPUT. The utility model discloses a leakage voltage drive detection circuitry detects the electric leakage, and output electric leakage shows the signal, has solved because of the bad problem that leads to detecting the electric leakage of ground connection, and application scope is wide, and all equipment that have metal casing can all use this mode to carry out the electric leakage detection.

Description

Circuit for detecting electric leakage through electric leakage voltage

Technical Field

The utility model relates to an electricity safety inspection technical field, concretely relates to circuit through leakage voltage detection electric leakage.

Background

With the development of national economy, more and more electric equipment, such as street lamps, transformer boxes, power distribution cabinets and other equipment facilities, are used. If the metal casing of these devices is not grounded well, a safety accident may occur when the devices leak electricity.

The safe voltage is the voltage which does not cause direct death or disability to people, and the 'safe extra-low voltage' which allows continuous contact under the general environmental condition is 36V. The industry stipulates that the safe voltage is not higher than 36V, the continuous contact safe voltage is 24V, the safe current is 10mA, and the damage degree of electric shock to human bodies mainly depends on the magnitude of the current passing through the human bodies and the electrifying time. The greater the current intensity, the greater the risk of mortality; the longer the duration, the greater the likelihood of death. The minimum current value which can cause people to feel is called sensing current, the alternating current is 1mA, and the direct current is 5 mA; the maximum current which a person can get rid of after getting an electric shock is called the free current, the alternating current is 10mA, and the direct current is 50 mA; the current which endangers life in a short time is called lethal current, for example, 100mA of current is passed through a human body for 1s, which can be enough to make a human fatal, so that the lethal current is 50 mA. In the case of a shock protection device, the current allowed to pass through the body can be typically considered as 30 mA. Due to the particularity of many electric occasions, the action current of the line leakage protector is designed to be 300mA (because the design is small, the circuit cannot be switched on in practical application), and potential safety hazards exist in the line leakage protector, such as a street lamp system.

The traditional leakage detection circuit generally detects through leakage current, if the metal shell has leakage current and is poor in grounding, the leakage current cannot be discharged, so that leakage current cannot be generated, and the leakage problem cannot be found through the technical means before a safety accident occurs.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides an in provide a circuit through electric leakage voltage detection electric leakage to solve among the prior art and lead to not detecting the problem of electric leakage because of the ground connection is bad. The utility model discloses a leakage voltage confirms to take place the electric leakage, is not restricted to and uses in a certain occasion, and all forceful electric power equipment that have metal casing can all use this mode to carry out electric leakage detection.

The embodiment of the utility model discloses following technical scheme:

the utility model provides a circuit for detecting electric leakage through electric leakage voltage, which comprises an optical coupling isolation circuit, a pulse filtering circuit, an analog amplifying circuit and a trigger suppression circuit which are connected in sequence; the optical coupling isolation circuit is used for converting leakage voltage into a leakage pulse signal, the pulse filtering circuit is used for filtering the leakage pulse signal, the analog amplifying circuit is used for carrying out amplitude conditioning on the filtered signal, and the trigger suppression circuit is used for converting the amplitude conditioned signal into a LEVEL signal LEVEL _ OUTPUT and latching or releasing the LEVEL signal LEVEL _ OUTPUT.

Further, the optical coupling isolation circuit comprises a half-wave rectifying circuit and a level conversion circuit, and the half-wave rectifying circuit is connected with the level conversion circuit.

Further, the half-wave rectifier circuit includes diode D1, opto-coupler U1 input and resistance R1, and the positive pole of earth leakage voltage is connected to diode D1's positive pole, and opto-coupler U1's positive pole is connected to diode D1's negative pole, and the negative pole of earth leakage voltage is connected through resistance R1 to opto-coupler U1's input negative pole, level conversion circuit includes opto-coupler U1 output and resistance R2, and the anodal power VCC that connects of opto-coupler U1's output, the one end of opto-coupler U1's output negative pole connecting resistance R8 and the one end of resistance R2, and the other end ground connection of resistance R2.

Furthermore, the pulse filtering circuit comprises a resistor R8 and a capacitor C20, the other end of the resistor R8 is connected with one end of the capacitor C20 and one end of the resistor R9, and the other end of the capacitor C20 is grounded.

Further, the analog amplification circuit comprises an operational amplifier U2A, the other end of a resistor R9 is connected with a positive input end of an operational amplifier U2A, an output end of the operational amplifier U2A is connected with one end of a resistor R7 and one end of a capacitor C19, the output end of the operational amplifier U2A is connected with a negative input end of the operational amplifier U2A through a resistor R3, the other end of the capacitor C19 is grounded, the other end of a resistor R7 is grounded through a resistor R10, an output end of the operational amplifier U2A forms a voltage division circuit through the resistor R7 and a resistor R10, and the negative input end of the operational amplifier U2A is grounded through a resistor R6.

Further, the trigger hold-down circuit comprises a trigger unit and a hold-down unit, and the trigger unit is connected with the hold-down unit.

Further, the trigger unit comprises an operational amplifier U2B, the voltage division is connected with a positive input end of an operational amplifier U2B, a power supply VCC forms a threshold voltage circuit through resistors R4 and R5, the threshold voltage is connected with a negative input end of the operational amplifier U2B, an output end of the operational amplifier U2B is connected with a positive electrode of a diode D2 and one end of a resistor R14, the release unit comprises an NPN triode Q1, an E electrode of the Q1 is grounded, a B electrode of the Q1 is connected with a singlechip control signal Unlock through a resistor R12, a C electrode of the Q1 is connected with a positive input end of the operational amplifier U2B, and a negative electrode of the diode D2 is connected with the positive input end of the operational amplifier U2B through a resistor R11.

Further, the circuit comprises a display circuit, the display circuit comprises an NPN triode Q2, a light emitting diode D3, a resistor R13 and a resistor R14, the other end of the resistor R14 is connected with the B pole of Q2, the E pole of Q2 is grounded, the C pole of Q2 is connected with one end of the resistor R13, VCC is connected with the anode of a light emitting diode D3, and the cathode of the light emitting diode D3 is connected with the other end of the resistor R13; when the OUTPUT voltage LEVEL _ OUTPUT is at a high LEVEL, the NPN transistor Q2 is turned on, the photodiode D3 is lit, and a detection of a leakage voltage is indicated.

The effects provided in the contents of the present invention are only the effects of the embodiments, not all the effects of the present invention, and one of the above technical solutions has the following advantages or advantageous effects:

the utility model provides a circuit through leakage voltage detection electric leakage detects the leakage voltage between metal casing and the zero line, it surpasses safe voltage to appear leakage voltage when metal casing, and when ground connection is bad, leakage voltage drives the opto-coupler, make the opto-coupler produce the electric leakage pulse signal, the electric leakage pulse signal is through the filtering of pulse filter circuit, enlarge through analog amplification circuit again, release the circuit through triggering at last and catch the signal, convert level signal into and latch, and show through emitting diode and remind, after the electric leakage problem is relieved, will latch the signal release again. The utility model discloses a leakage voltage drive detection circuitry detects the electric leakage, and output electric leakage shows the signal, has solved because of the bad problem that leads to detecting the electric leakage of ground connection, and application scope is wide, and all equipment that have metal casing can all use this mode to carry out the electric leakage detection.

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, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a block diagram of the circuit structure of the present invention;

fig. 2 is a schematic circuit diagram of an embodiment of the present invention;

in the figure, a 1-optical coupling isolation circuit, a 2-pulse filtering circuit, a 3-analog amplifying circuit and a 4-trigger suppression circuit are arranged.

Detailed Description

In order to clearly illustrate the technical features of the present invention, the present invention is explained in detail by the following embodiments in combination with the accompanying drawings. The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the disclosure of the present invention, the components and arrangements of specific examples are described below. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. It should be noted that the components illustrated in the figures are not necessarily drawn to scale. Descriptions of well-known components and processing techniques and processes are omitted so as to not unnecessarily limit the invention.

As shown in fig. 1 and 2, an embodiment of the present invention provides a circuit for detecting leakage through leakage voltage, which includes an optical coupling isolation circuit 1, a pulse filtering circuit 2, an analog amplifying circuit 3, and a trigger suppression circuit 4, which are connected in sequence; the optical coupling isolation circuit 1 is used for converting leakage voltage into a leakage PULSE signal PULSE, the PULSE filtering circuit 2 is used for filtering the leakage PULSE signal PULSE, the analog amplifying circuit 3 is used for carrying out amplitude conditioning on the filtered PULSE signal, and the trigger suppression circuit 4 is used for converting the amplitude conditioned PULSE signal into a LEVEL signal LEVEL _ OUTPUT and latching or releasing the LEVEL signal LEVEL _ OUTPUT.

The optical coupling isolation circuit comprises a half-wave rectifying circuit and a level conversion circuit, the half-wave rectifying circuit performs half-wave rectification on the leakage voltage, and the level conversion circuit converts the output of the half-wave rectifying circuit into a leakage PULSE signal PULSE.

The half-wave rectification circuit comprises a diode D1, an input end of an optocoupler U1 and a resistor R1, the anode of the diode D1 is connected with the anode of leakage voltage, the cathode of the diode D1 is connected with the anode of the input end of an optocoupler U1, and the cathode of the input end of an optocoupler U1 is connected with the cathode of the leakage voltage through the resistor R1.

The level switching circuit comprises an output end of the optocoupler U1 and a resistor R2, the anode of the output end of the optocoupler U1 is connected with a power supply VCC, the cathode of the output end of the optocoupler U1 is connected with one end of the resistor R8 and one end of the resistor R2, and the other end of the resistor R2 is grounded.

Referring to fig. 2, the position labeled PE is connected to the metal casing of the device, and the position labeled N is connected to the zero line, and since most of the leakage voltage is ac, half-wave rectification is performed through the diode D1; if metal casing and live wire take place the contact, the metal casing appears the earth leakage voltage promptly, when voltage reachd or surpassed safe voltage (36V), the opto-coupler can be driven to the electric current. In the positive half cycle of alternating current, metal casing passes through diode D1, opto-coupler U1, resistance R1 and zero line and forms one-way return circuit to drive opto-coupler U1, export electric leakage PULSE signal PULSE at opto-coupler U1, in the negative half cycle of alternating current, because diode D1's reverse cut-off characteristic causes one-way return circuit nonconducting, in order to prevent opto-coupler reverse input.

The pulse filtering circuit 2 comprises a resistor R8 and a capacitor C20, the other end of the resistor R8 is connected with the capacitor C20 and the resistor R9, and the other end of the capacitor C20 is grounded; in this embodiment, R8 and C20 form a low-pass filter, and since the duration of the leakage voltage is not fixed, the filter is used for sensitivity setting, and when the width of the leakage PULSE signal PULSE is less than a predetermined time, the PULSE can be attenuated to nearly 0V by the filter circuit, and the PULSE is filtered out and cannot pass through the filter, so that the PULSE cannot reach a subsequent circuit, and only a high-level PULSE longer than the predetermined time can pass through the PULSE filter circuit smoothly.

The analog amplification circuit 3 comprises an operational amplifier U2A, the other end of a resistor R9 is connected with the positive input end of an operational amplifier U2A, the output end of the operational amplifier U2A is connected with one end of a resistor R7 and one end of a capacitor C19, the negative input end of the operational amplifier U2A is connected through a resistor R3, the other end of the capacitor C19 is grounded, the other end of a resistor R7 is grounded through a resistor R10, the output end of the operational amplifier U2A forms a voltage division circuit through the resistor R7 and a resistor R10, and the negative input end of the operational amplifier U2A is grounded through a resistor R6.

In this embodiment, the analog amplification circuit 3 is an in-phase proportional amplification circuit composed of an operational amplifier U2A, resistors R3, R6, and R9, because the amplitudes of leakage pulse signals output by different leakage voltage driving optocouplers U1 are different, the analog amplification circuit 3 mainly conditions the amplitudes of the pulse signals, amplifies the pulse signals with different amplitudes to a required voltage threshold value, and simultaneously, the circuit realizes isolation of front and rear stage circuits, a capacitor C19 performs smooth filtering on an output signal of the operational amplifier U2A, the electric groups R7 and R10 divide the voltage of an output signal of the operational amplifier U2A, and the main purpose is to realize isolation of the output voltage of the rear stage operational amplifier U2B.

The trigger suppression circuit 4 comprises a trigger unit and a suppression unit, the trigger unit is responsible for converting a pulse signal generated by the voltage division circuit into a LEVEL signal LEVEL _ OUTPUT, the LEVEL _ OUTPUT is fed back to the input end of the trigger unit, and when the divided voltage is greater than a threshold voltage, the LEVEL _ OUTPUT is a high LEVEL signal; the voltage-releasing unit controls the OUTPUT voltage LEVEL _ OUTPUT of the trigger unit through the control signal Unlock, when the control signal Unlock is at a low LEVEL, high-LEVEL signal latching of LEVEL _ OUTPUT is achieved, when the control signal Unlock is at a high LEVEL, release of the LEVEL _ OUTPUT is achieved, and the OUTPUT end of the trigger unit is enabled to recover to a low LEVEL.

The trigger unit comprises an operational amplifier U2B, a positive input end of an operational amplifier U2B is connected with a voltage division mode, a power supply VCC forms a threshold voltage circuit through a resistor R4 and a resistor R5, the threshold voltage is connected with a negative input end of the operational amplifier U2B, and an output end of the operational amplifier U2B is connected with a positive electrode of a diode D2 and one end of a resistor R14.

The voltage release unit comprises an NPN triode Q1, the E pole of Q1 is grounded, the B pole of Q1 is connected with a control signal Unlock of a single chip microcomputer (the model of the single chip microcomputer is STM8L151C8T6) through a resistor R12, the C pole of Q1 is connected with the positive input end of an operational amplifier U2B, and the negative pole of a diode D2 is connected with the positive input end of the operational amplifier U2B through a resistor R11.

Since short-time leakage occurs at any time and pulse signals also occur at any time, if the leakage is not captured in time, the leakage is caused by passing through, and therefore, in order to better detect the occurrence of the leakage, the pulse signals need to be converted into LEVEL signals LEVEL _ OUTPUT.

When the circuit works, a control signal Unlock is set to be in a low LEVEL, an NPN triode Q1 is not conducted, if LEVEL _ OUTPUT is in a high LEVEL, the leakage is indicated to occur, the single chip microcomputer can judge whether the leakage occurs or not by detecting a LEVEL _ OUTPUT LEVEL signal, R4 and R5 divide VCC voltage for setting threshold voltage, the threshold voltage is provided for a negative input end of an operational amplifier U2B to serve as reference, if the divided voltage of a positive input end of the U2B exceeds the threshold voltage, the OUTPUT voltage LEVEL _ OUTPUT of the operational amplifier U2B is in a high LEVEL, meanwhile, an OUTPUT signal is fed back to a positive input end of the operational amplifier U2B through a diode D2 and a resistor R11, a pulse signal OUTPUT by a preceding stage circuit can be monitored in real time, the LEVEL _ OUTPUT high LEVEL signal is latched;

if the control signal Unlock is set to be at a high LEVEL, the NPN triode Q1 is turned on, the positive input terminal of the U2B is at 0V, the input of the operational amplifier U2B is inhibited, the OUTPUT voltage LEVEL _ OUTPUT of the U2B operational amplifier is a low LEVEL signal, and if the operational amplifier latches the high LEVEL signal at this time, the high LEVEL signal is also released, so that the release of the LEVEL _ OUTPUT signal is realized.

The circuit of the embodiment comprises a display circuit, wherein the display circuit comprises an NPN triode Q2, a light-emitting diode D3, a resistor R13 and a resistor R14, the other end of the resistor R14 is connected with the B pole of Q2, the E pole of Q2 is grounded, the C pole of Q2 is connected with one end of the resistor R13, VCC is connected with the anode of a light-emitting diode D3, and the cathode of the light-emitting diode D3 is connected with the other end of a resistor R13; when the OUTPUT voltage LEVEL _ OUTPUT is at a high LEVEL, the NPN transistor Q2 is turned on, the photodiode D3 is lit, and a detection of a leakage voltage is indicated.

The utility model discloses circuit theory of operation includes:

s1, converting the leakage voltage into a leakage PULSE signal PULSE through the optical coupling isolation circuit 1;

s2, the PULSE filter circuit 2 filters the leakage PULSE signal PULSE, when the width of the leakage PULSE signal PULSE is less than the specified time, the PULSE is filtered, only the high level PULSE which is more than the specified time can pass through the PULSE filter circuit 2 smoothly;

s3, the analog amplifying circuit 3 carries out amplitude conditioning on the filtered pulse signal;

and S4, the trigger hold-off circuit 4 is used for converting the pulse signal after amplitude conditioning into a LEVEL signal LEVEL _ OUTPUT, and latching or releasing the LEVEL signal LEVEL _ OUTPUT.

The method for triggering the latch or release of the hold-down circuit comprises the following steps:

when the control signal Unlock is at a low LEVEL and the divided voltage is greater than the threshold voltage, the OUTPUT voltage LEVEL _ OUTPUT of the trigger unit is at a high LEVEL, so that the high-LEVEL signal latch of LEVEL _ OUTPUT is realized;

when the Unlock signal is at a high LEVEL, the input end of the trigger unit is at 0V, and the OUTPUT voltage LEVEL _ OUTPUT is at a low LEVEL, so that the LEVEL _ OUTPUT signal is released.

The above description is only a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that a plurality of modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations are also considered as the protection scope of the present invention.

Claims

1. A circuit for detecting electric leakage through electric leakage voltage is characterized in that the circuit comprises an optical coupling isolation circuit, a pulse filtering circuit, an analog amplifying circuit and a trigger suppression circuit which are sequentially connected; the optical coupling isolation circuit is used for converting leakage voltage into a leakage pulse signal, the pulse filtering circuit is used for filtering the leakage pulse signal, the analog amplifying circuit is used for carrying out amplitude conditioning on the filtered signal, and the trigger suppression circuit is used for converting the amplitude conditioned signal into a LEVEL signal LEVEL _ OUTPUT and latching or releasing the LEVEL signal LEVEL _ OUTPUT.

2. The circuit for detecting leakage through leakage voltage according to claim 1, wherein the optical coupling isolation circuit comprises a half-wave rectifying circuit and a level conversion circuit, and the half-wave rectifying circuit is connected with the level conversion circuit.

3. The circuit of claim 2, wherein the half-wave rectification circuit comprises a diode D1, an input terminal of an optocoupler U1 and a resistor R1, an anode of a diode D1 is connected to an anode of a leakage voltage, a cathode of a diode D1 is connected to an anode of an input terminal of an optocoupler U1, a cathode of an input terminal of an optocoupler U1 is connected to a cathode of a leakage voltage through a resistor R1, the level conversion circuit comprises an output terminal of the optocoupler U1 and a resistor R2, an anode of an output terminal of the optocoupler U1 is connected to a power VCC, a cathode of an output terminal of the optocoupler U1 is connected to one end of a resistor R8 and one end of a resistor R2, and the other end of the resistor R2 is grounded.

4. The circuit for detecting leakage through leakage voltage according to claim 1, wherein the pulse filtering circuit comprises a resistor R8 and a capacitor C20, the other end of the resistor R8 is connected to one end of the capacitor C20 and one end of the resistor R9, and the other end of the capacitor C20 is grounded.

5. The circuit for detecting leakage through leakage voltage according to claim 1, wherein the analog amplifying circuit comprises an operational amplifier U2A, the other end of the resistor R9 is connected to the positive input terminal of the operational amplifier U2A, the output terminal of the operational amplifier U2A is connected to one end of a resistor R7 and one end of a capacitor C19, and is connected to the negative input terminal of the operational amplifier U2A through a resistor R3, the other end of the capacitor C19 is grounded, the other end of the resistor R7 is grounded through a resistor R10, the output terminal of the operational amplifier U2A forms a voltage dividing circuit by using the resistor R7 and a resistor R10, and the negative input terminal of the operational amplifier U2A is grounded through a resistor R6.

6. The circuit according to claim 1, wherein the trigger hold-down circuit comprises a trigger unit and a hold-down unit, and the trigger unit is connected with the hold-down unit.

7. The circuit for detecting leakage through leakage voltage according to claim 6, wherein the trigger unit comprises an operational amplifier U2B, the voltage division is connected to a positive input terminal of an operational amplifier U2B, the power source VCC forms a threshold voltage circuit through resistors R4 and R5, the threshold voltage circuit is connected to a negative input terminal of the operational amplifier U2B, an output terminal of the operational amplifier U2B is connected to a positive electrode of a diode D2 and one end of a resistor R14, the hold-down unit comprises an NPN triode Q1, an E electrode of Q1 is grounded, a B electrode of the Q1 is connected to the one-chip microcomputer control signal unrock through a resistor R12, a C electrode of the Q1 is connected to a positive input terminal of the operational amplifier U2B, and a negative electrode of the diode D2 is connected to a positive input terminal of the operational amplifier U2B through a resistor R11.

8. The circuit for detecting leakage current through leakage voltage according to claim 1, wherein the circuit comprises a display circuit, the display circuit comprises an NPN transistor Q2, a light emitting diode D3, a resistor R13 and a resistor R14, the other end of the resistor R14 is connected to the B pole of Q2, the E pole of Q2 is grounded, the C pole of Q2 is connected to one end of the resistor R13, VCC is connected to the anode of the light emitting diode D3, and the cathode of the light emitting diode D3 is connected to the other end of the resistor R13; when the OUTPUT voltage LEVEL _ OUTPUT is at a high LEVEL, the NPN transistor Q2 is turned on, the photodiode D3 is lit, and a detection of a leakage voltage is indicated.