An overcurrent automatic disconnect circuit for a device

Abstract

This utility model discloses an automatic overcurrent cut-off circuit for equipment in the field of overcurrent protection technology. It includes a transformer power supply circuit connected to a rectifier circuit, which in turn is connected to a shutdown circuit. The shutdown circuit is connected to both a protection circuit and the transformer power supply circuit, and also includes an anti-interference circuit. The output of the transformer power supply circuit is connected to the equipment or instrument for power supply. When an overcurrent occurs, the shutdown circuit is triggered, automatically cutting off the connection between the output of the transformer power supply circuit and the equipment or instrument, thus protecting the equipment. The protection circuit ensures the safety of the shutdown circuit, while the anti-interference circuit prevents malfunctions caused by external circuit power-on or external interference, thus avoiding power outages in the entire power circuit. This circuit is simple, effective, and exhibits high sensitivity, reliability, and stability, making it suitable for overcurrent protection of various equipment and instruments.

Description

Technical Field

[0001] This utility model relates to an automatic overcurrent cut-off circuit for equipment in the field of overcurrent protection technology. Background Technology

[0002] Equipment or instruments may experience various malfunctions and abnormal operating conditions during use. The most common and dangerous malfunction is short circuits of various forms, leading to overcurrent in the circuit. When a short circuit occurs, the short-circuit current flowing through the fault point is very large, potentially compromising the stability of the system's parallel operation. Current technology often incorporates overcurrent protection into the system. However, when external circuits are energized or when external interference occurs, the protection circuit may malfunction, causing a power outage in the entire circuit. Utility Model Content

[0003] The purpose of this invention is to provide an automatic overcurrent cut-off circuit for equipment, which is simple, effective, highly sensitive, reliable, and stable, and can be used for overcurrent protection of various equipment and instruments.

[0004] To achieve the above objectives, this utility model provides an overcurrent automatic cut-off circuit for equipment, including a transformer power supply circuit, which is connected to a rectifier circuit. The rectifier circuit is connected to a shutdown circuit, which is connected to a protection circuit and the transformer power supply circuit respectively. The shutdown circuit is also connected to an anti-interference circuit.

[0005] Compared with the prior art, the beneficial effects of this utility model are as follows: the output terminal of the transformer power supply circuit is connected to the equipment or instrument for power supply, and when an overcurrent occurs, the shutdown circuit is triggered, thereby automatically cutting off the connection between the output terminal of the transformer power supply circuit and the equipment or instrument, thus protecting the equipment. Furthermore, the protection circuit ensures the safety of the shutdown circuit, and the anti-interference circuit prevents the circuit from malfunctioning due to the moment the external circuit is powered on or when there is external interference, thereby avoiding the power outage of the entire power circuit. It is simple and effective, with high sensitivity, reliability and stability, and can be used for overcurrent protection of various equipment and instruments.

[0006] As a further improvement of this utility model, the shutdown circuit includes a thyristor VS1. The anode of the thyristor VS1 is connected to one end of the coil K of the relay, the other end of the coil K of the relay is connected to the positive terminal of the battery, the normally closed contact of the relay is connected to the output terminal of the transformer power supply circuit, and the cathode of the thyristor VS1 is connected to the negative terminal of the battery via the switch S.

[0007] When an overcurrent occurs, if the voltage between the gate (G) and gate (K) of thyristor VS1 exceeds the thyristor's turn-on voltage, thyristor VS1 will quickly turn on, thereby energizing the relay coil K. This causes the normally closed contact J of the relay to open, disconnecting the output of the transformer power supply circuit from the electrical equipment, thus protecting the equipment or instrument.

[0008] As a further improvement of this utility model, the transformer power supply circuit includes a transformer T, the input terminal of the transformer T is connected to the power supply, one output terminal of the transformer T is connected to the rectifier circuit, and the other output terminal of the transformer T is connected to the normally closed contact of the relay.

[0009] In this way, the power supply voltage is converted into the voltage required by the electrical equipment or instrument through the transformer, and the normally closed contact of the relay is connected to one of the output terminals of the transformer, thereby controlling the on and off of the transformer power supply circuit and the electrical equipment.

[0010] As a further improvement of this utility model, the rectifier circuit includes a resistor R1, which is connected in series to one output terminal of the transformer T. The two ends of the resistor R1 are connected to pin 1 and pin 3 of the rectifier bridge D1, respectively. Pin 2 of the rectifier bridge D1 is connected to the control electrode of the thyristor VS1, and pin 4 of the rectifier bridge D1 is connected to the cathode of the thyristor VS1.

[0011] In this way, the AC power from the transformer is converted into DC power by the rectifier circuit and applied to the G and K terminals of the thyristor. When there is an overcurrent, the voltage across the G and K terminals of the thyristor exceeds the thyristor's turn-on voltage, and the thyristor VS1 quickly turns on.

[0012] As a further improvement of this utility model, the protection circuit includes a diode D3. The cathode of diode D3 is connected to the other end of the coil K of the relay and one end of the resistor R4. The other end of the resistor R4 is connected to the anode of the light-emitting diode D2. The cathode of the light-emitting diode D2 is connected to the anode of diode D3. The anode of diode D3 is connected to one end of the coil K of the relay.

[0013] When the relay coil K is turned on, the LED D2 will light up, indicating that there is an overcurrent. The diode D3 can prevent the instantaneous induced voltage generated when the normally closed contact J is opened from damaging the thyristor.

[0014] As a further improvement of this utility model, the anti-interference circuit includes a resistor R2. One end of the resistor R2 is connected to pin 2 of the rectifier bridge D1. The other end of the resistor R2 is connected to one end of the capacitor C1 and one end of the resistor R3. The other end of the capacitor C1 is connected to pin 4 of the rectifier bridge D1 and the other end of the resistor R3. The other end of the resistor R3 is connected to the cathode of the thyristor VS1. One end of the resistor R3 is connected to the control electrode of the thyristor VS1.

[0015] Because the thyristor has high sensitivity, an RC delay circuit is constructed using resistor R2 and capacitor C1 to prevent the protection circuit from malfunctioning when the external circuit is powered on or when there is external interference, thus ensuring circuit stability. The function of resistor R3 in the circuit is to slowly discharge capacitor C1 after the pulse, preventing false triggering of the thyristor due to cumulative effects, also ensuring circuit stability. Attached Figure Description

[0016] Figure 1 This is the circuit diagram of this utility model. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings:

[0018] like Figure 1 The device shown uses an overcurrent automatic cut-off circuit, which includes a transformer power supply circuit connected to a rectifier circuit, a rectifier circuit connected to a shutdown circuit, a shutdown circuit connected to a protection circuit and a transformer power supply circuit, and an anti-interference circuit connected to the shutdown circuit.

[0019] The shutdown circuit includes thyristor VS1. The anode of thyristor VS1 is connected to one end of the coil K of the relay, the other end of the coil K of the relay is connected to the positive terminal of the battery, the normally closed contact of the relay is connected to the output terminal of the transformer power supply circuit, and the cathode of thyristor VS1 is connected to the negative terminal of the battery via switch S.

[0020] The transformer power supply circuit includes a transformer T. The input terminal of transformer T is connected to the power supply, one output terminal of transformer T is connected to the rectifier circuit, and the other output terminal of transformer T is connected to the normally closed contact of a relay.

[0021] The rectifier circuit includes a resistor R1, which is connected in series to one output terminal of the transformer T. The two ends of the resistor R1 are connected to pins 1 and 3 of the rectifier bridge D1, respectively. Pin 2 of the rectifier bridge D1 is connected to the control electrode of the thyristor VS1, and pin 4 of the rectifier bridge D1 is connected to the cathode of the thyristor VS1.

[0022] The protection circuit includes diode D3. The cathode of diode D3 is connected to the other end of the relay coil K and one end of resistor R4. The other end of resistor R4 is connected to the anode of LED D2. The cathode of LED D2 is connected to the anode of diode D3. The anode of diode D3 is connected to one end of the relay coil K.

[0023] The anti-interference circuit includes resistor R2. One end of resistor R2 is connected to pin 2 of rectifier bridge D1. The other end of resistor R2 is connected to one end of capacitor C1 and one end of resistor R3. The other end of capacitor C1 is connected to pin 4 of rectifier bridge D1 and the other end of resistor R3. The other end of resistor R3 is connected to the cathode of thyristor VS1. One end of resistor R3 is connected to the control electrode of thyristor VS1.

[0024] In this invention, when an overcurrent or short circuit occurs, if the voltage between the gate (G) and gate (K) of the thyristor VS1 exceeds the thyristor's turn-on voltage, the thyristor VS1 will quickly turn on, thereby energizing the relay coil K. This causes the normally closed contact J of the relay to open, disconnecting the transformer's output from the electrical equipment, thus protecting the equipment or instrument. Alternatively, the thyristor VS1 will be quickly triggered and turned on, the relay coil K will be energized, and the normally closed contact J will open, cutting off the connection between the transformer T's output and the equipment or instrument.

[0025] Because thyristors have a "memory" characteristic, once triggered to conduct, their control electrode loses its control function, the thyristor remains in a conducting state, the relay remains in a energized state, and the transformer T's output remains disconnected from the equipment for protection. At this point, only after the overcurrent or short-circuit fault is eliminated and the switch S is turned off will the thyristor's conducting state be broken, and the circuit's protection state be unlocked and reset.

[0026] Therefore, a rectifier bridge D1 is needed in the circuit to rectify the AC power, ensuring that the voltage across the GK terminals of the thyristor VS1 is always positive, thus guaranteeing effective triggering protection under any overcurrent or short-circuit conditions. LED D2 illuminates when the circuit is in protection mode, serving as a warning; diode D3 is to prevent the instantaneous induced voltage generated when the normally closed contact J of the relay opens from damaging the thyristor VS1.

[0027] Because the thyristor has high sensitivity, an RC delay circuit is constructed using resistor R2 and capacitor C1 to prevent the protection circuit from malfunctioning when the external circuit is powered on or when there is external interference, thus ensuring circuit stability. The function of resistor R3 in the circuit is to slowly discharge capacitor C1 after the pulse, preventing false triggering of the thyristor due to cumulative effects, also ensuring circuit stability.

[0028] This invention has a simple structure, good sensitivity, high safety and reliability, and stable operation. It can also provide overcurrent protection and prevent false triggering.

[0029] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed herein, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. An overcurrent automatic disconnection circuit for a device, characterized in that: It includes a transformer power supply circuit, which is connected to a rectifier circuit. The rectifier circuit is connected to a shutdown circuit, which is connected to both a protection circuit and the transformer power supply circuit. The shutdown circuit is also connected to an anti-interference circuit.

2. The automatic overcurrent cut-off circuit for equipment according to claim 1, characterized in that: The shutdown circuit includes thyristor VS1. The anode of thyristor VS1 is connected to one end of the coil K of the relay, the other end of the coil K of the relay is connected to the positive terminal of the battery, the normally closed contact of the relay is connected to the output terminal of the transformer power supply circuit, and the cathode of thyristor VS1 is connected to the negative terminal of the battery via switch S.

3. The automatic overcurrent cut-off circuit for equipment according to claim 2, characterized in that: The transformer power supply circuit includes a transformer T. The input terminal of transformer T is connected to the power supply, one output terminal of transformer T is connected to the rectifier circuit, and the other output terminal of transformer T is connected to the normally closed contact of a relay.

4. The automatic overcurrent cut-off circuit for equipment according to claim 3, characterized in that: The rectifier circuit includes a resistor R1, which is connected in series to one output terminal of the transformer T. The two ends of the resistor R1 are connected to pins 1 and 3 of the rectifier bridge D1, respectively. Pin 2 of the rectifier bridge D1 is connected to the control electrode of the thyristor VS1, and pin 4 of the rectifier bridge D1 is connected to the cathode of the thyristor VS1.

5. The automatic overcurrent cut-off circuit for equipment according to claim 4, characterized in that: The protection circuit includes diode D3. The cathode of diode D3 is connected to the other end of the relay coil K and one end of resistor R4. The other end of resistor R4 is connected to the anode of LED D2. The cathode of LED D2 is connected to the anode of diode D3. The anode of diode D3 is connected to one end of the relay coil K.

6. The automatic overcurrent cut-off circuit for a device according to claim 5, characterized in that: The anti-interference circuit includes resistor R2. One end of resistor R2 is connected to pin 2 of rectifier bridge D1. The other end of resistor R2 is connected to one end of capacitor C1 and one end of resistor R3. The other end of capacitor C1 is connected to pin 4 of rectifier bridge D1 and the other end of resistor R3. The other end of resistor R3 is connected to the cathode of thyristor VS1. One end of resistor R3 is connected to the control electrode of thyristor VS1.

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