An electric leakage detection protection circuit

Abstract

The utility model discloses a kind of electric leakage detection protection circuit, including electric leakage detection circuit, tripping drive circuit, control circuit and rectifier voltage reduction circuit, electric leakage detection circuit includes three-terminal voltage regulator IC1, mutual inductor magnetic ring, capacitor C2, capacitor C3, capacitor C4 and resistance R4, three-terminal voltage regulator IC1 has positive pole, negative pole and REF end.The utility model has the following advantages and effects: by adopting three-terminal voltage regulator IC1 combined with peripheral resistance capacitor network, a stable reference voltage is generated, to ensure that weak electric leakage signal collected by mutual inductor magnetic ring can be effectively amplified and compared, so that single-chip microcomputer U1 can acutely detect electric leakage signal, even if leakage current is very small, it can also be reliably detected, thereby greatly reducing the risk of false reporting, improve the sensitivity and reliability of overall protection.

Description

Technical Field

[0001] This utility model relates to the field of leakage current detection technology, and in particular to a leakage current detection and protection circuit. Background Technology

[0002] Leakage current detection and protection circuits are key components in electrical safety systems. Their core function is to promptly detect even weak leakage currents in the circuit and quickly cut off the power supply in case of danger. In existing technologies, leakage current detection and protection circuits typically use current transformers to detect leakage signals. However, the leakage signals induced by current transformers are extremely weak. If a stable and reliable reference voltage cannot be provided as a reference point for amplification and comparison, the microcontroller U1 may fail to detect the leakage, leading to protection failure. Therefore, how to construct a leakage current detection and protection circuit that can provide a stable reference voltage to ensure accurate identification of weak leakage signals is a core problem that urgently needs to be solved in this field. Utility Model Content

[0003] The purpose of this invention is to provide a leakage current detection and protection circuit to solve the problems mentioned in the background art.

[0004] The above-mentioned technical objective of this utility model is achieved through the following technical solution:

[0005] A leakage current detection and protection circuit includes a leakage current detection circuit for detecting leakage current signals, a tripping drive circuit for controlling a tripping coil to trigger a tripping action, a control circuit connected to the leakage current detection circuit and the tripping drive circuit respectively, and a rectifier and step-down circuit. The rectifier and step-down circuit rectifies and steps down AC mains power to form a DC power supply voltage, which is connected to the leakage current detection circuit and the control circuit. Upon detecting a leakage current signal, the leakage current detection circuit generates a leakage current feedback signal that can be sent to the control circuit. Upon receiving the leakage current feedback signal, the control circuit drives the tripping drive circuit to control the tripping coil to trigger a tripping action.

[0006] The leakage current detection circuit includes a three-terminal voltage regulator IC1, a current transformer magnetic ring, capacitors C2, C3, and C4, and a resistor R4. The three-terminal voltage regulator IC1 has a positive terminal, a negative terminal, and a REF terminal. The second port of the current transformer magnetic ring is connected to one end of capacitor C4, one end of capacitor C2, the REF terminal of the three-terminal voltage regulator IC1, and the negative terminal, and is pulled up to the supply voltage through resistor R4. The other end of capacitor C4 is grounded. The node where capacitor C2 is connected to the REF terminal of the three-terminal voltage regulator IC1 serves as a reference voltage terminal to provide a reference voltage. The first port of the current transformer magnetic ring is connected to the other end of capacitor C2 and connected to one end of capacitor C3. The other end of capacitor C3 is grounded. The node where capacitor C2 is connected to the other end of the reference voltage terminal serves as a leakage current signal acquisition terminal and is used to detect leakage current signals. The leakage current signal acquisition terminal is connected to the control circuit.

[0007] A further configuration is as follows: the leakage current detection circuit also includes resistors R1, R2, and R3, capacitor C1, and clamping diode D6; resistors R1, clamping diode D6, and capacitor C1 are connected in parallel across the two ends of the current transformer magnetic ring; resistor R2 is connected in series between the reference voltage terminal and the second port of the current transformer magnetic ring, and resistor R3 is connected in series between the leakage current signal acquisition terminal and the first port of the current transformer magnetic ring.

[0008] A further configuration is as follows: the tripping drive circuit includes diode D2, diode D4, unidirectional thyristor Q1, resistor R8, resistor R9, and capacitor C20. Diode D2, unidirectional thyristor Q1, and tripping coil form a circuit. The control terminal of unidirectional thyristor Q1 is connected to one end of capacitor C20, one end of resistor R8, and one end of resistor R9. The other end of capacitor C20 and the other end of resistor R9 are both grounded. The other end of resistor R8 is connected to the negative terminal of diode D4, and the positive terminal of diode D4 is connected to the control circuit.

[0009] A further configuration is as follows: the tripping drive circuit also includes a varistor RV1, a varistor RV2, a resistor R5, a capacitor C5, and a rectifier bridge D1. One end of the tripping coil is connected to the live wire of the AC mains and the varistor RV1, and the other end is connected to one end of the varistor RV2, one end of the resistor R5, and the positive terminal of the diode D2. The other ends of the varistor RV1 and the other ends of the varistor RV2 are both connected to the neutral wire of the AC mains. The other end of the resistor R5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is connected to one of the AC input terminals of the rectifier bridge D1. The other AC input terminal of the rectifier bridge D1 is connected to the neutral wire of the AC mains.

[0010] The negative terminal of diode D2 is connected to the positive terminal of unidirectional thyristor Q1, the negative terminal of unidirectional thyristor Q1 is grounded, the negative output terminal of rectifier bridge D1 is grounded, and the positive output terminal of rectifier bridge D1 is connected to the rectifier step-down circuit.

[0011] A further configuration is as follows: the rectifier-buck circuit includes a buck chip IC2, a Zener diode D3, a capacitor C6, and a capacitor C7; the positive output terminal of the rectifier bridge D1 is connected to the negative terminal of the Zener diode D3, one end of the capacitor C7, and the input terminal of the buck chip IC2; the output terminal of the buck chip IC2 is connected to one end of the capacitor C6, which outputs the supply voltage; the positive terminal of the Zener diode D3, the other end of the capacitor C7, the ground terminal of the buck chip IC2, and the other end of the capacitor C6 are all grounded.

[0012] A further configuration is as follows: the control circuit includes a microcontroller U1, and the reference voltage terminal, the leakage current signal acquisition terminal, and the positive terminal of the diode D4 are respectively connected to different enable pins of the microcontroller U1.

[0013] This utility model has the following beneficial effects:

[0014] By employing a leakage current detection circuit that includes a three-terminal voltage regulator IC1 and a current transformer magnetic ring, leakage current signals are accurately acquired. Combined with a rectifier-step-down circuit to provide a stable DC power supply, and a control circuit that processes the leakage current feedback signal in real time to drive the tripping drive circuit, the tripping coil is triggered to trip. This achieves rapid response and reliable protection against leakage current faults, effectively improving electrical safety. Furthermore, the overall circuit structure is reasonable, with strong anti-interference capabilities and high stability. Specifically, by using the three-terminal voltage regulator IC1 in conjunction with an external resistor-capacitor network, an extremely stable reference voltage is generated, ensuring that the weak leakage current signal acquired by the current transformer magnetic ring can be effectively amplified and compared. This allows the microcontroller U1 to sensitively detect the leakage current signal, even if the leakage current is very small, thus reliably detecting it and greatly reducing the risk of missed detections, thereby improving the overall sensitivity and reliability of the protection. Attached Figure Description

[0015] Figure 1 The circuit schematic is shown in the example diagram. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to the accompanying drawings.

[0017] As attached Figure 1 As shown;

[0018] This embodiment discloses a leakage current detection and protection circuit, including a leakage current detection circuit for detecting leakage current signals, a tripping drive circuit for controlling the tripping coil to trigger tripping action, a control circuit connected to the leakage current detection circuit and the tripping drive circuit respectively, and a rectifier and step-down circuit. The rectifier and step-down circuit is used to rectify and step down the AC mains power to form a DC power supply voltage, which is connected to the leakage current detection circuit and the control circuit. After detecting a leakage current signal, the leakage current detection circuit generates a leakage current feedback signal that can be sent to the control circuit. After receiving the leakage current feedback signal, the control circuit drives the tripping drive circuit to control the tripping coil to trigger tripping action.

[0019] The leakage current detection circuit includes a three-terminal voltage regulator IC1 and a current transformer magnetic ring (see...). Figure 1 The three-terminal regulator IC1 consists of capacitors C2, C3, C4, R4, R1, R11, R2, R3, C1, and clamping diode D6. It has a positive terminal, a negative terminal, and a REF terminal. Resistors R11, R1, clamping diode D6, and capacitor C1 are connected in parallel across the two ends of the transformer core. The second port of the transformer core, after passing through resistor R2, is connected to one end of capacitor C4, one end of capacitor C2, the REF terminal of the three-terminal regulator IC1, and the negative terminal. It is then pulled up through resistor R4 to connect to the 3.3V supply voltage. The other end of capacitor C4 is grounded. The node where capacitor C2 is connected to the REF terminal of the three-terminal regulator IC1 serves as the reference voltage terminal (see [link to relevant documentation]). Figure 1 The REF (marked in the middle) is used to provide the reference voltage; the first port of the transformer magnetic ring, after passing through resistor R3, is connected to the other end of capacitor C2, and then connected to one end of capacitor C3. The other end of capacitor C3 is grounded. The other end of capacitor C2 relative to the reference voltage terminal serves as the leakage current signal acquisition terminal (see...). Figure 1 The INP (marked in the middle) is used to detect leakage current signals, and the leakage current signal acquisition terminal is connected to the control circuit.

[0020] In this embodiment, the reference voltage is 1.25V. In the prior art, the voltage value of a typical leakage signal is 20mV, which is too low for the microcontroller U1 to detect. However, in this application, a 1.25V DC voltage component is superimposed on the 20mV leakage signal, increasing the leakage signal to 1.27V. This allows the microcontroller U1 to sensitively detect the leakage signal, significantly reducing the risk of missed detection and improving the overall sensitivity and reliability of the protection.

[0021] The tripping drive circuit includes diodes D2 and D4, a unidirectional thyristor Q1, resistors R8 and R9, capacitor C20, varistor RV1 and RV2, resistor R5, capacitor C5, and rectifier bridge D1. The tripping coil (see...) Figure 1 One end of the marked M) is connected to the live wire of the AC mains (see...). Figure 1 The L marked in the middle is connected to varistor RV1, and the other end is connected to one end of varistor RV2, one end of resistor R5 and the positive terminal of diode D2. The other ends of varistor RV1 and varistor RV2 are both connected to the neutral wire of AC mains (see...). Figure 1 The resistor R5 is connected to one end of capacitor C5, and the other end of capacitor C5 is connected to one of the AC input terminals of rectifier bridge D1. The other AC input terminal of rectifier bridge D1 is connected to the neutral wire of AC mains. The cathode of diode D2 is connected to the anode of unidirectional thyristor Q1, the cathode of unidirectional thyristor Q1 is grounded, the rectifier cathode output terminal of rectifier bridge D1 is grounded, and the rectifier anode output terminal of rectifier bridge D1 is connected to the rectifier step-down circuit. The control terminal of unidirectional thyristor Q1 is connected to one end of capacitor C20, one end of resistor R8, and one end of resistor R9. The other ends of capacitor C20 and resistor R9 are both grounded. The other end of resistor R8 is connected to the cathode of diode D4, and the anode of diode D4 is connected to the control circuit.

[0022] The rectifier-buck circuit includes a buck chip IC2, a Zener diode D3, capacitors C6 and C7; the positive output terminal of the rectifier bridge D1 is connected to the negative terminal of the Zener diode D3, one end of capacitor C7, and the input terminal of the buck chip IC2; the output terminal of the buck chip IC2 is connected to one end of capacitor C6, which outputs the supply voltage; the positive terminal of the Zener diode D3, the other end of capacitor C7, the ground terminal of the buck chip IC2, and the other end of capacitor C6 are all grounded.

[0023] The control circuit includes a microcontroller U1, with the reference voltage terminal, leakage current signal acquisition terminal, and the anode of diode D4 connected to different enable pins of microcontroller U1 (see...). Figure 1 On the 6th, 7th and 1st feet.

[0024] Preferably, in this embodiment, the microcontroller U1 is model CIU32F003J5S6; the step-down chip IC2 is model MD75 series; the three-terminal regulator IC1 is model ME432; and the rectifier bridge D1 is model MB6S.

[0025] This specific embodiment is merely an explanation of the present utility model and is not intended to limit the present utility model. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of the present utility model, they are protected by patent law.

Claims

1. A leakage current detection and protection circuit, characterized in that: The device includes a leakage current detection circuit for detecting leakage current signals, a tripping drive circuit for controlling the tripping coil to trigger a tripping action, a control circuit connected to the leakage current detection circuit and the tripping drive circuit respectively, and a rectifier and step-down circuit. The rectifier and step-down circuit is used to rectify and step down AC mains power to form a DC power supply voltage, which is connected to the leakage current detection circuit and the control circuit. Upon detecting a leakage current signal, the leakage current detection circuit generates a leakage current feedback signal that can be sent to the control circuit. After receiving the leakage current feedback signal, the control circuit drives the tripping drive circuit to control the tripping coil to trigger a tripping action. The leakage current detection circuit includes a three-terminal voltage regulator IC1, a current transformer magnetic ring, capacitors C2, C3, and C4, and a resistor R4. The three-terminal voltage regulator IC1 has a positive terminal, a negative terminal, and a REF terminal. The second port of the current transformer magnetic ring is connected to one end of capacitor C4, one end of capacitor C2, the REF terminal of the three-terminal voltage regulator IC1, and the negative terminal, and is pulled up to the supply voltage through resistor R4. The other end of capacitor C4 is grounded. The node where capacitor C2 is connected to the REF terminal of the three-terminal voltage regulator IC1 serves as a reference voltage terminal to provide a reference voltage. The first port of the current transformer magnetic ring is connected to the other end of capacitor C2 and connected to one end of capacitor C3. The other end of capacitor C3 is grounded. The node where capacitor C2 is connected to the other end of the reference voltage terminal serves as a leakage current signal acquisition terminal and is used to detect leakage current signals. The leakage current signal acquisition terminal is connected to the control circuit.

2. The leakage current detection and protection circuit according to claim 1, characterized in that: The leakage current detection circuit also includes resistors R1, R2, and R3, capacitor C1, and clamping diode D6; resistors R1, clamping diode D6, and capacitor C1 are connected in parallel across the two ends of the current transformer magnetic ring; resistor R2 is connected in series between the reference voltage terminal and the second port of the current transformer magnetic ring, and resistor R3 is connected in series between the leakage current signal acquisition terminal and the first port of the current transformer magnetic ring.

3. The leakage current detection and protection circuit according to claim 1, characterized in that: The tripping drive circuit includes diode D2, diode D4, unidirectional thyristor Q1, resistor R8, resistor R9, and capacitor C20. Diode D2, unidirectional thyristor Q1, and tripping coil form a circuit. The control terminal of unidirectional thyristor Q1 is connected to one end of capacitor C20, one end of resistor R8, and one end of resistor R9. The other end of capacitor C20 and the other end of resistor R9 are both grounded. The other end of resistor R8 is connected to the negative terminal of diode D4, and the positive terminal of diode D4 is connected to the control circuit.

4. The leakage current detection and protection circuit according to claim 3, characterized in that: The tripping drive circuit also includes a varistor RV1, a varistor RV2, a resistor R5, a capacitor C5, and a rectifier bridge D1. One end of the tripping coil is connected to the live wire of the AC mains and the varistor RV1, and the other end is connected to one end of the varistor RV2, one end of the resistor R5, and the positive terminal of the diode D2. The other ends of the varistor RV1 and the other ends of the varistor RV2 are both connected to the neutral wire of the AC mains. The other end of the resistor R5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is connected to one of the AC input terminals of the rectifier bridge D1. The other AC input terminal of the rectifier bridge D1 is connected to the neutral wire of the AC mains. The negative terminal of diode D2 is connected to the positive terminal of unidirectional thyristor Q1, the negative terminal of unidirectional thyristor Q1 is grounded, the negative output terminal of rectifier bridge D1 is grounded, and the positive output terminal of rectifier bridge D1 is connected to the rectifier step-down circuit.

5. A leakage current detection and protection circuit according to claim 4, characterized in that: The rectifier-step-down circuit includes a step-down chip IC2, a Zener diode D3, a capacitor C6, and a capacitor C7; the positive output terminal of the rectifier bridge D1 is connected to the negative terminal of the Zener diode D3, one end of the capacitor C7, and the input terminal of the step-down chip IC2; the output terminal of the step-down chip IC2 is connected to one end of the capacitor C6, and this end outputs the supply voltage. The positive terminal of Zener diode D3, the other end of capacitor C7, the ground terminal of step-down chip IC2, and the other end of capacitor C6 are all grounded.

6. The leakage current detection and protection circuit according to claim 1, characterized in that: The control circuit includes a microcontroller U1, and the reference voltage terminal, the leakage current signal acquisition terminal, and the positive terminal of diode D4 are respectively connected to different enable pins of the microcontroller U1.

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