CN211670620U

CN211670620U - Leakage protection circuit

Info

Publication number: CN211670620U
Application number: CN201821551444.4U
Authority: CN
Inventors: 吕敬标
Original assignee: Shenzhen Xinyi Technology Co Ltd
Current assignee: Shenzhen Xinyi Technology Co Ltd
Priority date: 2018-09-21
Filing date: 2018-09-21
Publication date: 2020-10-13
Anticipated expiration: 2028-09-21

Abstract

The utility model relates to a leakage protection circuit, which comprises a leakage detection unit for detecting whether leakage occurs in the circuit and outputting a leakage signal when leakage occurs; first return circuit, including control switch, voltage divider and protector, control switch with the parallelly connected back of voltage divider with the protector is established ties, first return circuit is receiving when the leakage signal passes through the protector cuts off the power supply line, and electric leakage detecting element 1 is the self-excited oscillation module, and its detection winding 11 and the self-excited oscillation circuit that includes the leakage current sensor, and the self-excited oscillation circuit includes: first operational amplifier U1, second resistance R2, third resistance R3, fourth resistance R4, the utility model discloses electric leakage detection unit among the electric leakage protection circuit is for prior art, can realize detecting function basis on, and required components and parts are few, circuit structure is simple, and manufacturing cost reduces.

Description

Leakage protection circuit

Technical Field

The utility model relates to an earth leakage protection circuit.

Background

The arrangement of an electric leakage protection device in a low-voltage distribution system is one of effective measures for preventing human body electric shock accidents, and is also one of technical measures for preventing electric fire and electric equipment damage accidents caused by electric leakage. Common leakage protection devices include leakage protectors, circuit breakers, and the like. In the prior art, when a load runs on line, whether a leakage fault exists in a circuit is detected through a detection element, such as a mutual inductor, in a specific application, a live wire and a zero wire of a certain phase wire penetrate through a magnetic ring of the mutual inductor to form a primary coil of the mutual inductor, and a winding wound on the magnetic ring forms a secondary side coil of the mutual inductor. If no leakage occurs, the sum of the current vectors flowing through the live wire and the zero wire is equal to zero, so that corresponding induced electromotive force cannot be generated on a secondary side coil of the mutual inductor. If the current leakage occurs, the sum of the current vectors of the live wire and the zero wire is not equal to zero, so that induced electromotive force is generated on a secondary side coil of the mutual inductor, and an executing mechanism, such as a release, is triggered to cut off a power supply at a fault position. However, in the prior art, the leakage detection unit has more components, complex element connection relationship and higher production cost.

SUMMERY OF THE UTILITY MODEL

For solving the technical defect, the utility model discloses a following technical scheme:

the utility model provides a leakage protection circuit, which comprises a leakage detection unit 1, a control unit and a control unit, wherein the leakage detection unit is used for detecting whether leakage occurs in the circuit or not and outputting a leakage signal when the leakage occurs; first return circuit, including control switch, voltage divider and protector, control switch with the parallelly connected back of voltage divider with the protector is established ties, first return circuit is receiving when the leakage signal passes through the protector cuts off the power supply line, and electric leakage detecting element 1 is the self-excited oscillation module, and its detection winding 11 and the self-excited oscillation circuit that includes the leakage current sensor, and the self-excited oscillation circuit includes: the circuit comprises a first operational amplifier U1, a second resistor R2, a third resistor R3 and a fourth resistor R4.

Further, the first operational amplifier U1 is powered with circuitry + 12/-12V. One end of the detection winding 11 is connected with one end of a fourth resistor R4, an inverted input end pin 1 of the first operational amplifier and one end of a first resistor R1, the other end of the detection winding 11 is connected with one end of a third resistor R3 and an output end of a first operational amplifier U1, and a pin 3 is connected between the control switch and the protector; one end of the second resistor R2 is connected with the other end of the third resistor R3 and the pin 2 of the positive input end of the first operational amplifier U1; a positive power supply terminal pin of the first operational amplifier U1 is connected with a system power supply +12V, and a negative power supply terminal pin is connected with the system power supply-12V; the other ends of the second resistor R2 and the fourth resistor R4 are connected with the system ground.

Further, one end of the first resistor R1 and the output end of the self-oscillation module are connected with the other end of the first resistor R1 and one end of the first capacitor C1; the other end of the first capacitor C1 is connected to system ground.

The beneficial effects of the utility model are that the utility model discloses electric leakage detection unit among the earth leakage protection circuit is for prior art, on can realizing detecting the function basis, required components and parts are few, circuit structure is simple, manufacturing cost reduces.

Drawings

Fig. 1 is a schematic circuit diagram of the present invention.

Fig. 2 is a circuit structure diagram of the leakage detecting unit of the leakage protection circuit of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1 to 2, an electric leakage protection circuit includes an electric leakage detection unit 1 for detecting whether electric leakage occurs in an electric device and outputting an electric leakage signal when the electric leakage occurs; the first circuit 2 comprises a control switch 21, a voltage divider 22 and a protector 23, wherein the control switch 21 and the voltage divider 22 are connected in parallel and then connected in series with the protector 23; when the first loop 2 receives the leakage signal, the protector 23 cuts off a power supply line; the switch control circuit 3 is used for switching off the control switch 21 when the current in the first loop 2 is greater than or equal to a preset value, so that the current flows through the voltage divider 22 to be divided; when the current in the first loop 2 is smaller than the preset value, the control switch 21 is turned on. Specifically, for example, after the leakage detecting unit 1 detects that the electrical device 4 leaks electricity, it outputs a leakage signal to the first loop 2, and after the first loop 2 receives the leakage signal, the protector 23 in the first loop 2 controls the actuator 5 to operate, so as to disconnect the power supply 6 at the electrical device 4 where the electrical leakage occurs, and prevent an operator from getting an electric shock after touching the metal casing of the electrical device 4. In the prior art, in order to ensure that the protector 23 generates enough force to control the operation of the actuator 5, the current flowing through the protector 23 is generally relatively large, that is, the current in the first circuit 2 is relatively large, but the protector 23 is easy to heat up and reduce the service life when working under a large current for a long time, and the protector 23 has a large impact on the actuator 5 matched with the protector when the current flowing through the protector 23 is too large, so that the actuator 5 is damaged. When the current in the first loop 2 is greater than or equal to the preset value, the switch control circuit 3 controls the control switch 21 to be switched off, and at the moment, the voltage divider 22 is switched into the first loop 2 to divide the voltage, so that the current in the first loop 2 is reduced, the current flowing through the protector 23 is naturally reduced, the impact of the protector on the actuating mechanism 5 is reduced, and the service lives of the protector 23 and the actuating mechanism 5 are prolonged; when the current in the first loop 2 is smaller than the preset value, the switch control circuit 3 turns on the control switch 21, and at this time, the voltage divider 22 is shorted by the control switch 21, and switches out the first loop 2, so that the protector 23 flows a sufficient current to operate the actuator 5. Therefore, the leakage protection circuit of the embodiment can control the actuator 5 to disconnect the power supply at the fault to realize the leakage protection function when the protector 23 generates the leakage, and simultaneously can reduce the current flowing through the protector 23 as much as possible, prevent the protector from generating excessive impact on the actuator 5, and prolong the electrical life of the protector.

The leakage detecting unit 1 is a self-oscillation module, which includes a detection winding 11 of a leakage current sensor and a self-oscillation circuit. A self-oscillation circuit includes: the circuit comprises a first operational amplifier U1, a second resistor R2, a third resistor R3 and a fourth resistor R4. The first operational amplifier U1 is powered with circuitry + 12/-12V. One end of the detection winding 11 is connected with one end of a fourth resistor R4, an inverted input end pin 1 of the first operational amplifier and one end of a first resistor R1, the other end of the detection winding 11 is connected with one end of a third resistor R3 and an output end of a first operational amplifier U1, and a pin 3 is connected between the control switch and the protector; one end of the second resistor R2 is connected with the other end of the third resistor R3 and the pin 2 of the positive input end of the first operational amplifier U1; a positive power supply terminal pin of the first operational amplifier U1 is connected with a system power supply +12V, and a negative power supply terminal pin is connected with the system power supply-12V; the other ends of the second resistor R2 and the fourth resistor R4 are both connected with the system ground, one end of the first resistor R1 is connected with the output end of the self-oscillation module, namely one end of the detection winding 11, and the other end of the first resistor R1 is connected with one end of the first capacitor C1; the other end of the first capacitor C1 is connected to system ground.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. An earth leakage protection circuit, characterized in that: the leakage detection unit is used for detecting whether leakage occurs in the circuit and outputting a leakage signal when the leakage occurs; first return circuit, including control switch, voltage divider and protector, control switch with the parallelly connected back of voltage divider with the protector is established ties, first return circuit is receiving when the leakage signal passes through the protector cuts off the power supply line, its characterized in that: the leakage detecting unit 1 is a self-excited oscillation module including a detection winding 11 of a leakage current sensor and a self-excited oscillation circuit, the self-excited oscillation circuit including: the circuit comprises a first operational amplifier U1, a second resistor R2, a third resistor R3 and a fourth resistor R4.

2. The leakage protection circuit according to claim 1, wherein: the first operational amplifier U1 is powered by +12/-12V, one end of a detection winding 11 is connected with one end of a fourth resistor R4, the reverse input end pin 1 of the first operational amplifier and one end of a first resistor R1, the other end of the detection winding 11 is connected with one end of a third resistor R3 and the output end of the first operational amplifier U1, and the pin 3 is connected between a control switch and a protector; one end of the second resistor R2 is connected with the other end of the third resistor R3 and the pin 2 of the positive input end of the first operational amplifier U1; a positive power supply terminal pin of the first operational amplifier U1 is connected with a system power supply +12V, and a negative power supply terminal pin is connected with the system power supply-12V; the other ends of the second resistor R2 and the fourth resistor R4 are connected with the system ground.

3. The leakage protection circuit according to claim 2, wherein: one end of the first resistor R1, the other end of the self-oscillation module output end of the first resistor R1 and one end of the first capacitor C1; the other end of the first capacitor C1 is connected to system ground.