Anti-misconnection high-voltage protection circuit for switching value interface

Abstract

The utility model provides a switching value interface misconnection prevention high-voltage protection circuit, which comprises a first thermistor (PPTC1), a second thermistor (PPTC2), an overvoltage protection circuit (1), a step-down circuit (2) and an isolation circuit (3), and is characterized in that the input end of the overvoltage protection circuit (1) is respectively connected with the first thermistor (PPTC1) and the second thermistor (PPTC2); the output end of the overvoltage protection circuit (1) is connected with the input end of the step-down circuit (2), and the output end of the step-down circuit (2) is connected with the input end of the isolation circuit (3). The beneficial effects of the utility model are that the anti-misconnection high-voltage protection circuit for the switching value interface solves the problems that the equipment is burnt down due to the fact that a worker accesses three-phase power into the equipment due to misoperation, and the equipment is damaged due to the impact of surge current.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, in particular to a high-voltage protection circuit for preventing misconnection of a switch quantity interface. Background Art

[0002] Existing smart gateways and smart meters need to collect a lot of switch quantity data and can also detect various information on the three-phase circuit. Since the three-phase power access terminal and the switch quantity access terminal are the same terminal and are close in position, on-site workers sometimes connect the three-phase power to the switch quantity interface during wiring, thus burning the equipment.

[0003] Problems and defects of existing technology:

[0004] The switch interfaces on existing gateway devices are all signal line interfaces with very low withstand voltage. Although the existing technology can protect the back-end circuit, it cannot be restored. Some of them can only be protected instantaneously, but they will burn out the equipment over a long period of time. Utility Model Content

[0005] In order to solve the problem that three-phase electricity is connected to the switch quantity input interface and causes equipment to burn out, and to prevent the impact of surge current from causing equipment damage, the utility model provides a switch quantity interface anti-misconnection high-voltage protection circuit.

[0006] The utility model provides a switch quantity interface anti-misconnection high-voltage protection circuit, comprising a first thermistor, a second thermistor, an overvoltage protection circuit, a step-down circuit, and an isolation circuit. The input end of the overvoltage protection circuit is respectively connected to the first thermistor and the second thermistor, the output end of the overvoltage protection circuit is connected to the input end of the step-down circuit, and the output end of the step-down circuit is connected to the input end of the isolation circuit.

[0007] As a further improvement of the utility model, the overvoltage protection circuit includes a first transient voltage suppression diode, a second transient voltage suppression diode, and a third transient voltage suppression diode, one end of the first transient voltage suppression diode is responsible for connecting to the ground terminal, and the other end of the first transient voltage suppression diode is respectively connected to one end of the first thermistor, one end of the second transient voltage suppression diode, and the input end of the step-down circuit;

[0008] One end of the second transient voltage suppression diode is also connected to one end of the first thermistor and the input end of the step-down circuit respectively, and the other end of the second transient voltage suppression diode is connected to one end of the second thermistor, one end of the third transient voltage suppression diode and the input end of the step-down circuit respectively;

[0009] One end of the third transient voltage suppression diode is also connected to the input end of the step-down circuit and one end of the second thermistor respectively, and the other end of the third transient voltage suppression diode is responsible for connecting to the ground end.

[0010] As a further improvement of the utility model, the step-down circuit includes a first inductor and a second inductor, one end of the first inductor is respectively connected to the other end of the first transient voltage suppression diode, one end of the first thermistor, and one end of the second transient voltage suppression diode, and the other end of the first inductor is connected to the input end of the isolation circuit;

[0011] One end of the second inductor is respectively connected to the other end of the second transient voltage suppression diode, one end of the second thermistor, and one end of the third transient voltage suppression diode, and the other end of the second inductor is connected to the input end of the isolation circuit.

[0012] As a further improvement of the utility model, the switch interface anti-misconnection high-voltage protection circuit also includes a first resistor, one end of the first resistor is connected to the other end of the second inductor, and the other end of the first resistor is connected to the input end of the isolation circuit.

[0013] As a further improvement of the present invention, the isolation circuit is an optocoupler, the optocoupler anode is connected to the other end of the first inductor, the optocoupler cathode is connected to the other end of the first resistor, and the optocoupler emitter is connected to the ground terminal.

[0014] As a further improvement of the utility model, the switch interface anti-misconnection high-voltage protection circuit also includes a second resistor, one end of the second resistor is connected to the power supply voltage VCC 3.3V, and the other end of the second resistor is connected to the collector of the optocoupler.

[0015] The beneficial effect of the utility model is that the switch quantity interface anti-misconnection high-voltage protection circuit of the utility model solves the problem that workers connect three-phase electricity to equipment due to misoperation, causing equipment burning, and surge current impact causing equipment damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a circuit diagram of the utility model. DETAILED DESCRIPTION

[0017] like Figure 1As shown, the utility model discloses a switch quantity interface anti-misconnection high-voltage protection circuit, including a first thermistor PPTC1, a second thermistor PPTC2, an overvoltage protection circuit 1, a step-down circuit 2, and an isolation circuit 3. The input end of the overvoltage protection circuit 1 is respectively connected to one end of the first thermistor PPTC1 and one end of the second thermistor PPTC2, the output end of the overvoltage protection circuit 1 is connected to the input end of the step-down circuit 2, the output end of the step-down circuit 2 is connected to the input end of the isolation circuit 3, the isolation circuit 3 is used to be connected to the GPIO port, the other end of the first thermistor PPTC1 is connected to the three-phase voltage DI+ port, and the other end of the second thermistor PPTC2 is connected to the three-phase voltage DI- port.

[0018] The overvoltage protection circuit 1 includes a first transient voltage suppression diode D1, a second transient voltage suppression diode D2, and a third transient voltage suppression diode D3, wherein one end of the first transient voltage suppression diode D1 is responsible for connecting to the ground terminal, and the other end of the first transient voltage suppression diode D1 is respectively connected to one end of the first thermistor PPTC1, one end of the second transient voltage suppression diode D2, and the input end of the step-down circuit 2;

[0019] One end of the second transient voltage suppression diode D2 is also connected to one end of the first thermistor PPTC1 and the input end of the step-down circuit 2 respectively, and the other end of the second transient voltage suppression diode D2 is connected to one end of the second thermistor PPTC2, one end of the third transient voltage suppression diode D3 and the input end of the step-down circuit 2 respectively;

[0020] One end of the third transient voltage suppression diode D3 is also connected to the input end of the step-down circuit 2 and one end of the second thermistor PPTC2 respectively, and the other end of the third transient voltage suppression diode D3 is responsible for connecting to the ground end.

[0021] The step-down circuit 2 comprises a first inductor L1 and a second inductor L2, one end of the first inductor L1 is respectively connected to the other end of the first transient voltage suppression diode D1, one end of the first thermistor PPTC1, and one end of the second transient voltage suppression diode D2, and the other end of the first inductor L1 is connected to the input end of the isolation circuit 3;

[0022] One end of the second inductor L2 is respectively connected to the other end of the second transient voltage suppression diode D2, one end of the second thermistor PPTC2, and one end of the third transient voltage suppression diode D3, and the other end of the second inductor L2 is connected to the input end of the isolation circuit 3.

[0023] The switch interface misconnection protection circuit also includes a first resistor R1 , one end of the first resistor R1 is connected to the other end of the second inductor L2 , and the other end of the first resistor R1 is connected to the input end of the isolation circuit 3 .

[0024] The isolation circuit 3 is an optocoupler U1 , an anode of the optocoupler U1 is connected to the other end of the first inductor L1 , a cathode of the optocoupler U1 is connected to the other end of the first resistor R1 , and an emitter of the optocoupler U1 is connected to the ground.

[0025] The switch interface misconnection protection circuit also includes a second resistor R2, one end of the second resistor R2 is connected to the power supply voltage VCC 3.3V, and the other end of the second resistor R2 is respectively connected to the collector of the optocoupler U1 and the GPIO port.

[0026] The first thermistor PPTC1 and the second thermistor PPTC2 are made of polymer materials filled with carbon black particles. This material has a certain conductivity and can therefore pass the rated current. If the current passing through the thermistor is too high, its heating power is greater than the heat dissipation power. At this time, the temperature of the thermistor will begin to rise continuously, and the polymer matrix in the thermistor will begin to expand, which will separate the carbon black particles and cause the resistance to rise, thereby effectively reducing the current in the circuit. At this time, there is still a small current passing through the circuit, and this current keeps the thermistor at a sufficient temperature to keep it in a high resistance state. When the fault is eliminated, the thermistor cools down quickly and returns to its original low resistance state, so that it can work again like a new thermistor.

[0027] The first transient voltage suppression diode D1, the second transient voltage suppression diode D2, and the third transient voltage suppression diode D3 are overvoltage protection devices with bidirectional voltage stabilization characteristics and bidirectional negative resistance characteristics. They are used in various AC and DC power supply circuits to suppress instantaneous overvoltage. When a surge pulse voltage appears instantly in the protected circuit, the diode can quickly break down by Zener, changing from a high resistance state to a low resistance state, shunting and clamping the surge voltage, thereby protecting the components in the circuit from being damaged by the instantaneous surge pulse voltage.

[0028] Working principle:

[0029] When the three-phase voltage enters from DI+ and DI-, the first transient voltage suppression diode D1, the second transient voltage suppression diode D2, and the third transient voltage suppression diode D3 are triggered first, and the current is conducted to the ground, thereby clamping the voltage at the DI+ and DI- terminals to a very low value, and the current increases rapidly. At this time, the first thermistor PPTC1 and the second thermistor PPTC2 will heat up sharply, and the resistance will increase, cutting off the back-end path and playing a protective role. Until the input high voltage is eliminated, the first thermistor PPTC1 and the second thermistor PPTC2 cool down, the resistance value decreases, and the circuit works normally. The first inductor L1 and the second inductor L2 can further reduce the residual voltage, and the optocoupler U1 can play an isolation role to ensure that the back-end circuit is not affected.

[0030] The beneficial effect of the utility model is that the switch quantity interface anti-misconnection high-voltage protection circuit of the utility model solves the problem that workers connect three-phase electricity to equipment due to misoperation, causing equipment burning, and surge current impact causing equipment damage.

[0031] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A high voltage protection circuit for preventing misconnection of a switch interface, characterized in that: The invention comprises a first thermistor (PPTC1), a second thermistor (PPTC2), an overvoltage protection circuit (1), a voltage reduction circuit (2), and an isolation circuit (3); the input end of the overvoltage protection circuit (1) is connected to the first thermistor (PPTC1) and the second thermistor (PPTC2), respectively; the output end of the overvoltage protection circuit (1) is connected to the input end of the voltage reduction circuit (2); and the output end of the voltage reduction circuit (2) is connected to the input end of the isolation circuit (3).

2. The switch interface anti-misconnection high voltage protection circuit according to claim 1, characterized in that: The overvoltage protection circuit (1) comprises a first transient voltage suppression diode (D1), a second transient voltage suppression diode (D2), and a third transient voltage suppression diode (D3). One end of the first transient voltage suppression diode (D1) is responsible for connecting to the ground end, and the other end of the first transient voltage suppression diode (D1) is respectively connected to one end of the first thermistor (PPTC1), one end of the second transient voltage suppression diode (D2), and the input end of the step-down circuit (2); one end of the second transient voltage suppression diode (D2) is also respectively connected to one end of the first thermistor (PPTC1) and the input end of the step-down circuit (2), and the other end of the second transient voltage suppression diode (D2) is respectively connected to one end of the second thermistor (PPTC2), one end of the third transient voltage suppression diode (D3), and the input end of the step-down circuit (2); One end of the third transient voltage suppression diode (D3) is also connected to the input end of the step-down circuit (2) and one end of the second thermistor (PPTC2), respectively, and the other end of the third transient voltage suppression diode (D3) is responsible for connecting to the ground end.

3. The switch interface anti-misconnection high voltage protection circuit according to claim 2, characterized in that: The step-down circuit (2) comprises a first inductor (L1) and a second inductor (L2). One end of the first inductor (L1) is respectively connected to the other end of the first transient voltage suppression diode (D1), one end of the first thermistor (PPTC1), and one end of the second transient voltage suppression diode (D2), and the other end of the first inductor (L1) is connected to the input end of the isolation circuit (3); one end of the second inductor (L2) is respectively connected to the other end of the second transient voltage suppression diode (D2), one end of the second thermistor (PPTC2), and one end of the third transient voltage suppression diode (D3), and the other end of the second inductor (L2) is connected to the input end of the isolation circuit (3).

4. The switch interface anti-misconnection high voltage protection circuit according to claim 3, characterized in that: The switch quantity interface misconnection prevention high voltage protection circuit also includes a first resistor (R1), one end of the first resistor (R1) is connected to the other end of the second inductor (L2), and the other end of the first resistor (R1) is connected to the input end of the isolation circuit (3).

5. The switch interface anti-misconnection high voltage protection circuit according to claim 4, characterized in that: The isolation circuit (3) is an optocoupler (U1), the anode of the optocoupler (U1) is connected to the other end of the first inductor (L1), the cathode of the optocoupler (U1) is connected to the other end of the first resistor (R1), and the emitter of the optocoupler (U1) is connected to the ground.

6. The switch interface anti-misconnection high voltage protection circuit according to claim 5, characterized in that: The switch quantity interface misconnection protection circuit also includes a second resistor (R2), one end of the second resistor (R2) is connected to the power supply voltage VCC 3.3V, and the other end of the second resistor (R2) is connected to the collector of the optical coupler (U1).

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