Leakage protector circuit with overcurrent protection

Abstract

The utility model relates to a leakage protector circuit with an overcurrent protection function, which relates to a leakage protector, solves the problem that an existing leakage protection circuit has no alarm prompt and no timely power failure during overcurrent, and comprises a current acquisition resistor R16, a current acquisition module, an overcurrent acquisition module, a time delay module and an overcurrent protection module, the current acquisition module comprises an operational amplifier U2B, the input end of the operational amplifier U2B is set as a reference voltage reference point A and a current acquisition point B, the output end of the operational amplifier U2B is set as an overcurrent output point C, and the current acquisition point B is connected with a current acquisition resistor R16. The overcurrent indication module comprises an overcurrent indication lamp LED2 and a transistor Q1 which are connected in series. The overcurrent output point C is connected in series in the overcurrent indication module, the time delay module is connected in parallel to one side of the overcurrent indication module, the overcurrent protection module is provided with an operational amplifier U2A, and the input end of the operational amplifier U2A is set as a benchmark reference voltage point D and an input point E; and the power-off protection effect is achieved.

Description

Technical Field

[0001] This utility model relates to a residual current device (RCD), and in particular to an RCD circuit with overcurrent protection. Background Technology

[0002] In the current use of electric water heaters or faucets, the high power of electric water heaters, coupled with the possibility of users replacing them with higher-power ones, can lead to increased electrical load and current, causing the power socket and power cord to overheat rapidly. Prolonged use of these devices can easily result in a fire. Therefore, a protective circuit is needed to provide an alarm and automatic power cut-off in the event of an overcurrent, thereby preventing potential safety hazards. Utility Model Content

[0003] The purpose of this invention is to provide a leakage current protection circuit with overcurrent protection, which solves the problem that existing leakage current protection circuits do not provide alarm prompts or timely power cut-off when there is overcurrent.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] This utility model provides a leakage current protection circuit with overcurrent protection. The circuit has trip coils installed on the live and neutral wires of the power input terminal. The output terminal of the trip coil is connected to a rectifier diode D6, which is connected to the anode of a silicon controlled rectifier (SCR1). The control electrode of the SCR1 is connected to the leakage current protection module. Both the live and neutral wires pass through the zero-sequence current transformer of the leakage current protection module. The circuit includes a current acquisition resistor R16, a current acquisition module, an overcurrent acquisition module, a delay module, and an overcurrent protection module. The current acquisition resistor R16 is connected in series at the output terminal of the neutral wire. The current acquisition module includes an operational amplifier U2B. The input terminals of operational amplifier U2B are set as reference voltage point A and current acquisition point B, respectively. The output terminal of operational amplifier U2B is set as overcurrent output point C. The current acquisition point B is connected to the current acquisition resistor R16. The overcurrent indication module includes an overcurrent indicator LED2 and a transistor Q1 connected in series. The overcurrent output point C is connected in series within the overcurrent indication module. The delay module is connected in parallel on one side of the overcurrent indication module. The overcurrent protection module is equipped with operational amplifier U2A. The input terminals of operational amplifier U2A are set as reference voltage point D and input point E, respectively. The output terminal of operational amplifier U2A is set as point F. Point F is connected to the positive terminal of diode D3. The negative terminal of diode D3 is connected to the control electrode of SCR1 thyristor.

[0006] Furthermore, it also includes a leakage current protection chip U1, and the control electrode of the trip coil and the SCR1 thyristor are both connected to the leakage current protection chip U1.

[0007] Furthermore, resistor R16 is connected in series with resistor R20 between the current acquisition resistor and the current acquisition point B.

[0008] Furthermore, the reference voltage reference point A is connected in series with resistors R21 and R22, and the other ends of R21 and R22 are respectively connected to resistor R13 in the overcurrent indication module and the emitter of transistor Q1.

[0009] Furthermore, the overcurrent indicator LED2 is a self-flashing light-emitting diode. The anode and cathode of the overcurrent indicator LED2 are connected to the power supply voltage VCC and the transistor Q1, respectively, and a resistor R18 is connected in series between the cathode of the overcurrent indicator LED2 and the collector of the transistor Q1.

[0010] Furthermore, a resistor R19 and a capacitor C15 are connected in series within the delay module. One end of the resistor R19 is connected to the power supply voltage VCC, and the capacitor C15 is necessarily connected to the ground terminal. The other ends of the resistor R19 and the capacitor C15 are both connected to the negative terminal of the diode D5, and the negative terminal of the diode D5 is connected to the input point E.

[0011] Furthermore, the reference voltage point D is connected in series with resistors R14 and R9.

[0012] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art:

[0013] This invention enables the following: When a working current flows through the current acquisition resistor R16 in the power-on state, the voltage drop generated across its two ends is transmitted to the current acquisition module via resistor R20. When the current reaches a preset value, the transistor Q1 in the overcurrent acquisition module is turned on, and LED2 flashes. At the same time, the delay module activates the overcurrent protection module, which transmits a signal to the control electrode of the SCR1 thyristor and turns on the SCR1 thyristor, thus achieving power-off protection. Attached Figure Description

[0014] The following sections will describe some specific embodiments of the present invention in a detailed manner by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or components. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings:

[0015] Figure 1 This is a circuit diagram of an embodiment of the present invention;

[0016] Figure 2 This is a circuit diagram showing the connection of the current acquisition resistor R16, the current acquisition module, the overcurrent acquisition module, the delay module, and the overcurrent protection module of this utility model.

[0017] The reference numerals in the attached figures are explained as follows:

[0018] 1. Current acquisition module; 2. Overcurrent acquisition module; 3. Delay module; 4. Overcurrent protection module; 5. Leakage protection chip U1; 6. Leakage protection module; 7. Tripping coil. Detailed Implementation

[0019] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0020] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 As shown, a trip coil 7 is installed on the live and neutral wires of the power input terminal of the circuit. The output terminal of the trip coil 7 is also connected to the rectifier diode D6. The rectifier diode D6 is connected to the anode of the SCR1 thyristor and the leakage protection chip U15. The control electrode of the SCR1 is connected to the leakage protection module 6. Both the live and neutral wires pass through the zero-sequence current transformer of the leakage protection module 6. Under normal conditions, the trip coil 7 works normally, and the power supply provides normal power to the load. When leakage occurs, the leakage protection module 6 will quickly feed back to the control electrode of the SCR1 to make it conduct. At the same time, after receiving the signal from the SCR1 thyristor, the leakage protection chip U15 will also output a signal, causing the trip coil 7 to trip and disconnect, so that the power supply no longer provides power to the load.

[0023] like Figure 2 As shown, it includes a current acquisition resistor R16, a current acquisition module 1, an overcurrent acquisition module 2, a delay module 3, and an overcurrent protection module 4.

[0024] The current acquisition resistor R16 is connected in series at the output terminal of the neutral line. The current acquisition module 1 includes an operational amplifier U2B. The input terminals of the operational amplifier U2B are set as the reference voltage reference point A and the current acquisition point B, respectively. The output terminal of the operational amplifier U2B is set as the overcurrent output point C. The current acquisition point B is connected to the current acquisition resistor R16. A resistor R20 is connected in series between the current acquisition resistor R16 and the current acquisition point B. When a working current flows through the current acquisition resistor R16, the voltage drop generated across the resistor is transmitted to point B through R20. When the current exceeds the preset value, the voltage at the current acquisition point B is greater than that at the reference reference point A. At this time, the overcurrent output point C outputs a high level.

[0025] The reference voltage at point A serves as the base voltage for overcurrent sampling and protection action. Different preset values ​​can be obtained by adjusting the reference voltage at point A. Resistors R21 and R22 are connected in series at point A, and the voltage value at point A is obtained by the voltage divider between resistors R22 and R21. The voltage value at point A can be adjusted by adjusting the resistance values ​​of resistors R22 and R21.

[0026] The overcurrent indicator module includes an overcurrent indicator LED2 and a transistor Q1 connected in series. The overcurrent output point C is connected in series within the overcurrent indicator module. Resistors R21 and R22 are connected at their other ends to resistor R13 within the overcurrent indicator module and the emitter of transistor Q1, respectively. The overcurrent indicator LED2 is a self-flashing LED. The anode and cathode of LED2 are connected to the supply voltage VCC and transistor Q1, respectively, and a resistor R18 is connected in series between the cathode of LED2 and the collector of transistor Q1. When point C outputs a high level, transistor Q1 conducts, and LED2 flashes to alert the user.

[0027] Delay module 3 is connected in parallel to the overcurrent indicator module. Resistor R19 and capacitor C15 are connected in series within delay module 3. Overcurrent protection module 4 includes operational amplifier U2A. The input terminals of operational amplifier U2A are set to the reference voltage at point D and input point E, respectively. The output terminal of operational amplifier U2A is set to point F. One end of resistor R19 is connected to the supply voltage VCC, and capacitor C15 is always connected to ground. The other ends of resistor R19 and capacitor C15 are both connected to the cathode of diode D5. The cathode of diode D5 is connected to input point E. After transistor Q1 is turned on, resistor R19 charges capacitor C15 and applies it to input point E. When the voltage at input point E is greater than the reference voltage at point D, a high voltage is output at output point F. Output point F is connected to the anode of diode D3. The cathode of diode D3 is connected to the control electrode of SCR1. This voltage passes through D3 to the control electrode of SCR1, turning on SCR14 and achieving power-off protection.

[0028] The reference voltage at point D is connected in series with resistors R14 and R9. Changing the values ​​of resistors R14 and R9 changes the reference voltage at point D, which in turn adjusts the overcurrent protection action time.

[0029] When powered on, if a working current flows through resistor R16, the voltage drop across the resistor is transmitted to point B via resistor R20. When the current reaches a certain preset value, the voltage at point B is greater than that at point A, at which point C outputs a high voltage. Simultaneously, Q1 conducts, and LED2 flashes. Also, R19 charges C15, which in turn powers point E. When the voltage at point E is greater than that at point D, a high voltage is output at point F. This voltage is transmitted through D3 to the control electrode of SCR1, causing SCR14 to conduct, thus achieving power-off protection.

[0030] When there is no overcurrent, both points C and F output a low level;

[0031] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this invention and implement it accordingly. They should not be used to limit the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this invention should be covered within the scope of protection of this utility model.

Claims

1. A leakage current protection circuit with overcurrent protection, wherein a trip coil is provided on the live wire and neutral wire of the power input terminal of the circuit, the output terminal of the trip coil is also connected to a rectifier diode D6, the rectifier diode D6 is connected to the anode of a silicon controlled rectifier (SCR1), the control electrode of the SCR1 is connected to a leakage current protection module, and both the live wire and the neutral wire pass through the zero-sequence current transformer of the leakage current protection module, characterized in that... The system includes a current acquisition resistor R16, a current acquisition module, an overcurrent acquisition module, a delay module, and an overcurrent protection module. The current acquisition resistor R16 is connected in series at the output terminal of the neutral line. The current acquisition module includes an operational amplifier U2B, whose input terminals are set as a reference voltage reference point A and a current acquisition point B, respectively. The output terminal of the operational amplifier U2B is set as an overcurrent output point C, and the current acquisition point B is connected to the current acquisition resistor R16. The overcurrent indication module includes an overcurrent indicator LED2 and a transistor Q1 connected in series. The overcurrent output point C is connected in series within the overcurrent indication module. The delay module is connected in parallel to one side of the overcurrent indication module. The overcurrent protection module includes an operational amplifier U2A, whose input terminals are set as a reference voltage reference point D and an input point E, respectively. The output terminal of the operational amplifier U2A is set as point F, and point F is connected to the positive terminal of diode D3. The negative terminal of diode D3 is connected to the control electrode of SCR1 (Syroscope).

2. A leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: It also includes a leakage current protection chip U1, and the trip coil and the control electrode of the SCR1 thyristor are both connected to the leakage current protection chip U1.

3. A leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: An resistor R20 is connected in series between the current acquisition resistor R16 and the current acquisition point B.

4. A leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: The reference voltage reference point A is connected in series with resistors R21 and R22. The other ends of R21 and R22 are respectively connected to resistor R13 in the overcurrent indicator module and the emitter of transistor Q1.

5. A leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: The overcurrent indicator LED2 is a self-flashing light-emitting diode. The anode and cathode of the overcurrent indicator LED2 are connected to the power supply voltage VCC and the transistor Q1, respectively, and a resistor R18 is connected in series between the cathode of the overcurrent indicator LED2 and the collector of the transistor Q1.

6. A leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: The delay module contains a resistor R19 and a capacitor C15 connected in series. One end of the resistor R19 is connected to the power supply voltage VCC, and the capacitor C15 is always connected to the ground terminal. The other ends of the resistor R19 and the capacitor C15 are both connected to the negative terminal of the diode D5, and the negative terminal of the diode D5 is connected to the input point E.

7. The leakage current protection circuit with overcurrent protection according to claim 1, characterized in that: The reference voltage at point D is connected in series with resistors R14 and R9.

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