An automatic on-off optical coupling isolation circuit for short circuit current limiter

Abstract

This utility model belongs to the field of short-circuit current limiter on / off control technology, and discloses an automatic on / off optocoupler isolation circuit for a short-circuit current limiter, including a first power supply, an access switch S1, resistors R41 and R1, capacitor C1, optocoupler U1, a second power supply, resistors R2 and C2, and a circuit breaker; the external on / off contact of the circuit breaker is connected to the access switch S1 through a preset access line; in this utility model, the external on / off contact of the circuit breaker is connected to the access switch S1 through a preset access line, and the automatic on / off control of the short-circuit current limiter is realized by the closing and opening of the access switch S1, without manual intervention, thus improving the automation level and operating efficiency of the system; by introducing the optocoupler U1, effective isolation between the input signal and the output signal is achieved, which helps to protect other components in the circuit from possible interference or damage caused by the input signal.

Description

Technical Field

[0001] This utility model belongs to the technical field of short-circuit current limiters, and specifically relates to an automatic optocoupler isolation circuit for short-circuit current limiters. Background Technology

[0002] A fault current limiter (FCL), also known as a fault current limiter, is a device used to limit the magnitude of short-circuit current in a power system. It is primarily used in high-voltage power systems, especially in situations requiring short-circuit current limitation. For example, installing limiters at critical nodes such as large power plants and substations can effectively improve system safety and stability. FCLs are typically connected in series in the electrical circuit and can effectively limit fault current, including its first peak value. During normal operation, the FCL presents a low-impedance or zero-impedance state. When a fault occurs, it quickly interrupts the short-circuit fault. Currently, existing FCLs cannot automatically engage or disengage based on the power system's operating mode, requiring personnel to operate them locally or remotely, increasing operational risks. Furthermore, manual operation is prone to delays or misoperations, affecting system safety and stability. Utility Model Content

[0003] To address the technical problems existing in the prior art, this utility model provides an automatic optocoupler isolation circuit for short-circuit current limiters, which solves the problem that the existing short-circuit current limiters have high operational risks during the activation and deactivation process, which can easily lead to untimely activation or deactivation or misoperation, affecting the safety and stability of the system.

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

[0005] This utility model provides

[0006] An automatic switching optocoupler isolation circuit for a short-circuit current limiter is characterized by comprising a first power supply, an access switch S1, a resistor R41, a resistor R1, a capacitor C1, an optocoupler U1, a second power supply, a resistor R2, a capacitor C2, and a circuit breaker.

[0007] The first end of resistor R41 is connected to the first power supply, and the second end of resistor R41 is connected to the first end of resistor R1, the first end of capacitor C2, and the positive terminal of the light-emitting diode in optocoupler U1; the first end of access switch S1 is connected to the first GND terminal, and the second end of access switch S1 is connected to the second end of resistor R1, the second end of capacitor C1, and the negative terminal of the light-emitting diode in optocoupler U1.

[0008] The collector of the phototransistor in the optocoupler U1 is connected to the second power supply; the emitter of the phototransistor in the optocoupler U1, the first end of the resistor R2, and the first end of the capacitor C2 are all connected to the VOUT terminal; wherein, the VOUT terminal is used to connect to the short-circuit current limiter; the second end of the resistor R2 and the second end of the capacitor C2 are both connected to the second GND terminal; the external switching contact of the circuit breaker is connected to the access switch S1 through a preset access line.

[0009] Furthermore, it also includes capacitor C3; the first end of capacitor C3 is connected to the first power supply, and the second end of capacitor C3 is connected to the second end of the access switch S1.

[0010] Furthermore, it also includes an RC filter circuit; the RC filter circuit is located at the output terminal of the optocoupler U1.

[0011] Furthermore, the RC filter circuit includes a resistor R. L and capacitor C L ;

[0012] The phototransistor emitter in the optocoupler U1, the first terminal of the resistor R2, and the first terminal of the capacitor C2 are connected to the resistor R... L The first terminals are all connected, and the resistor R L The second terminal and the capacitor C L The first terminal is connected to both the VOUT terminal; the capacitor C L The second end is connected to the second GND end.

[0013] Furthermore, the resistor R L The resistance of the capacitor is 10KΩ, and the capacitor C L Its capacitance is 0.1 μF.

[0014] Furthermore, the optocoupler U1 is a TLP521 type optocoupler.

[0015] Furthermore, the optocoupler U1 is a TLP627 type optocoupler.

[0016] Furthermore, the short-circuit current limiter is powered by 220VAC mains power or 220VAC inverter power.

[0017] Furthermore, the first power supply is a +24V power supply, and the second power supply is a +5V power supply.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] This utility model provides an automatic switching optocoupler isolation circuit for a short-circuit current limiter. The external switching contacts of the circuit breaker are connected to an access switch S1 via a preset access line. The opening and closing of the access switch S1 enables automatic switching on and off of the short-circuit current limiter without manual intervention, improving the system's automation level and operational efficiency. The introduction of optocoupler U1 effectively isolates the input and output signals, helping to protect other components in the circuit from potential interference or damage from the input signals. Simultaneously, optocoupler U1 converts the input signal from the circuit breaker's switching contacts into a level signal for subsequent circuit processing, facilitating subsequent signal processing and judgment. When the circuit breaker's switching contacts are closed, the access switch S1... The synergistic effect of components such as resistor R41 and capacitor C1 illuminates the LED of optocoupler U1, thereby driving the phototransistor to conduct and outputting a high-level signal at the VOUT terminal, which in turn drives the short-circuit current limiter to work. Conversely, when the switching contact is open, the VOUT terminal outputs a low-level signal, and the short-circuit current limiter deactivates. This utility model has a simple circuit structure, which is easy to implement and debug. At the same time, it has the advantages of effective signal isolation and conversion, stable power supply, flexible access method, reliable signal processing and judgment, and strong anti-interference ability, so that the circuit has broad application prospects and practical value in the automatic switching control of short-circuit current limiters. Furthermore, the simple circuit structure design not only reduces manufacturing costs but also improves the reliability and stability of the circuit. Attached Figure Description

[0020] Figure 1 A schematic diagram of the automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter provided by this utility model;

[0021] Figure 2 This is the output waveform of the oscilloscope at the VOUT terminal in the 50mV range of this utility model. Detailed Implementation

[0022] To make the technical problem solved by this utility model, the technical solution, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of this utility model. It should be understood that the specific embodiments described herein are merely illustrative of this utility model and are not intended to limit it.

[0023] As attached Figure 1 As shown, this utility model provides an automatic switching optocoupler isolation circuit for a short-circuit current limiter, including a first power supply, an access switch S1, a resistor R41, a resistor R1, a capacitor C1, an optocoupler U1, a second power supply, a resistor R2, a capacitor C2, a circuit breaker, a capacitor C3, and an RC filter circuit.

[0024] The first power supply is connected to the first end of the resistor R41, and the second end of the resistor R41 is connected to the first end of the resistor R1, the first end of the capacitor C2, and the positive terminal of the light-emitting diode in the optocoupler U1; preferably, the first power supply is a +24V power supply; the first end of the access switch S1 is connected to the first GND terminal, and the second end of the access switch S1 is connected to the second end of the resistor R1, the second end of the capacitor C1, and the negative terminal of the light-emitting diode in the optocoupler U1; wherein, the optocoupler U1 is a TLP521 type optocoupler or a TLP627 type optocoupler.

[0025] The collector of the phototransistor in the optocoupler U1 is connected to the second power supply; preferably, the second power supply is a +5V power supply; the emitter of the phototransistor in the optocoupler U1, the first end of the resistor R2, and the first end of the capacitor C2 are all connected to the VOUT terminal; wherein, the VOUT terminal is used to connect to the short-circuit current limiter; the second end of the resistor R2 and the second end of the capacitor C2 are all connected to the second GND terminal.

[0026] The external connection / disconnection point of the circuit breaker is connected to the access switch S1 via a preset access line. The short-circuit current limiter is powered by 220VAC mains power or 220VAC inverter power supply. The preset access line includes a short access line and a long access line. The long access line is a double-stranded wire with a length of 6m and a diameter of 2.5mm. The length of the short access line is less than the length of the long access line.

[0027] The first terminal of capacitor C3 is connected to +24V, and the second terminal of capacitor C3 is connected to the second terminal of the access switch S1; preferably, the capacitance of capacitor C3 is 0.1μF.

[0028] The RC filter circuit is located at the output terminal of the optocoupler U1.

[0029] Specifically, the RC filter circuit includes a resistor R L and capacitor C L The phototransistor emitter in the optocoupler U1, the first terminal of the resistor R2, and the first terminal of the capacitor C2 are connected to the resistor R... L The first terminals are all connected, and the resistor R L The second terminal and the capacitor C L The first terminal is connected to both the VOUT terminal; the capacitor C L The second terminal is connected to the second GND terminal; preferably, the resistor R L The resistance of the capacitor is 10KΩ, and the capacitor C L Its capacitance is 0.1 μF.

[0030] Working principle:

[0031] (1) Normal state: When the circuit is in normal state, the connection switch S1 is in the open state. At this time, the circuit formed by the first power supply, resistor R41, resistor R1, capacitor C1 and the light-emitting diode in optocoupler U1 is cut off, and the light-emitting diode does not emit light. Since the light-emitting diode does not emit light, the phototransistor in optocoupler U1 is in the cut-off state, and the VOUT terminal outputs a low level. Therefore, the short-circuit current limiter is in the unactivated state.

[0032] (2) Engagement state: When the short-circuit current limiter needs to be engaged, the access switch S1 is closed by an external control signal. At this time, the first power supply charges the capacitor C1 through resistor R41 and resistor R1, and the LED lights up at the same time. After the LED lights up, the phototransistor in the optocoupler U1 is turned on, and the VOUT terminal outputs a high level. This high level is used to drive the short-circuit current limiter to work.

[0033] (3) Exit State: When it is necessary to exit the short-circuit current limiter, disconnect the access switch S1 through the external control signal. At this time, the circuit formed by the first power supply, resistor R41, resistor R1, capacitor C1 and the light-emitting diode in optocoupler U1 is cut off, and the light-emitting diode does not light up; since the light-emitting diode does not light up, the phototransistor in optocoupler U1 is in the cut-off state again, the VOUT terminal outputs a low level, and the short-circuit current limiter exits the operation.

[0034] Performance testing process:

[0035] Connect the input terminal of the oscilloscope to the VOUT terminal to display the output waveform of the VOUT terminal.

[0036] (1) The short-circuit current limiter is powered by 220VAC mains power. The external switching contacts of the circuit breaker are connected in series to the access switch S1 by using a short connection line or a long connection line. The opening and closing of the access switch S1 is controlled. The output waveform of the VOUT terminal is observed on an oscilloscope. The results of the output waveform observation show that the output waveform of the VOUT terminal is at a high level when the access switch S1 is closed and opened.

[0037] (2) A 220VAC inverter power supply is used to power the short-circuit current limiter. The external switching contacts of the circuit breaker are connected in series to the access switch S1 by the access short line. By controlling the closing and opening of the access switch S1, the output waveform of the VOUT terminal is observed on the oscilloscope. The result of observing the output waveform shows that the output waveform of the VOUT terminal is at a high level when the access switch S1 is closed and opened.

[0038] (3) A 220VAC inverter power supply is used to power the short-circuit current limiter. The external switching contacts of the circuit breaker are connected in series to the access switch S1 using a long access line. By controlling the closing and opening of the access switch S1, the output waveform of the VOUT terminal is observed on an oscilloscope. The results of the output waveform observation show that when the access switch S1 is closed, the output waveform of the VOUT terminal is at a high level; when the access switch S1 is open, the output waveform of the VOUT terminal is at a low level. The output waveforms are as follows: Figure 2 As shown; Appendix Figure 2 As shown, when the oscilloscope is set to the 50mV range, the output is a low level, and the waveform is a smooth straight line.

[0039] The automatic switching circuit described in this embodiment connects the external switching contacts of the circuit breaker to the access switch S1 via a preset access line. The input signal from the switching contacts of the circuit breaker is converted into a level signal for subsequent circuit processing through the optocoupler U1, facilitating subsequent signal processing and judgment. When the switching contacts of the circuit breaker are closed, the LED of the optocoupler U1 is lit through the synergistic effect of the access switch S1, resistor R41, and capacitor C1, thereby driving the phototransistor to conduct and outputting a high-level signal at the VOUT terminal. Conversely, when the switching contacts are open, the VOUT terminal outputs a low-level signal, enabling the circuit to accurately and reliably handle the exit control of the short-circuit current limiter.

[0040] Performance test results:

[0041] The test results of the above embodiments are shown in Table 1 below.

[0042]

[0043] As can be seen from Table 1 above, by adding an RC filter circuit to the output side of optocoupler U1, the optocoupler output is tested to be normal and smooth. After testing, it was found that the TLP521 optocoupler and TLP627 optocoupler are roughly the same in circuit application. Among them, the TLP521 optocoupler is a slow optocoupler, and the output amplitude and frequency are different. When the external switching contacts of the circuit breaker are connected in series in the circuit, there is no difference in the output effect whether the contacts are on the common 24V side or the common GND side.

[0044] It should be noted that by connecting a 0.1uF capacitor in parallel on the input side of optocoupler U1 and adding an RC filter circuit on the output side of optocoupler U1, the problem of intermittent output of the optocoupler isolation circuit can be effectively solved when the short-circuit current limiter is powered by a 220VAC inverter power supply and the external switching contacts of the circuit breaker have long leads and the contacts are not closed.

[0045] The automatic switching circuit provided by this utility model has a relatively simple structure, is easy to implement and debug, and not only reduces manufacturing costs, but also improves the reliability and stability of the circuit. The external switching contacts of the circuit breaker are connected to the access switch S1 through a preset access line, which enables the automatic switching circuit to flexibly control the switching of different short-circuit current limiters, thereby improving the versatility and applicability of the circuit.

[0046] The above embodiments are merely one of the implementation methods to achieve the technical solution of this utility model. The scope of protection claimed by this utility model is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this utility model.

Claims

1. An automatic on / off optocoupler isolation circuit for a short-circuit current limiter, characterized in that, It includes a first power supply, a connection switch S1, a resistor R41, a resistor R1, a capacitor C1, an optocoupler U1, a second power supply, a resistor R2, a capacitor C2, and a circuit breaker. The first end of resistor R41 is connected to the first power supply, and the second end of resistor R41 is connected to the first end of resistor R1, the first end of capacitor C2, and the positive terminal of the light-emitting diode in optocoupler U1; the first end of access switch S1 is connected to the first GND terminal, and the second end of access switch S1 is connected to the second end of resistor R1, the second end of capacitor C1, and the negative terminal of the light-emitting diode in optocoupler U1. The collector of the phototransistor in the optocoupler U1 is connected to the second power supply; the emitter of the phototransistor in the optocoupler U1, the first end of the resistor R2, and the first end of the capacitor C2 are all connected to the VOUT terminal; wherein, the VOUT terminal is used to connect to the short-circuit current limiter; the second end of the resistor R2 and the second end of the capacitor C2 are both connected to the second GND terminal; the external switching contact of the circuit breaker is connected to the access switch S1 through a preset access line.

2. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 1, characterized in that, It also includes capacitor C3; the first end of capacitor C3 is connected to the first power supply, and the second end of capacitor C3 is connected to the second end of the access switch S1.

3. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 2, characterized in that, It also includes an RC filter circuit; the RC filter circuit is located at the output terminal of the optocoupler U1.

4. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 3, characterized in that, The RC filter circuit includes a resistor R. L and capacitor C L ; The phototransistor emitter in the optocoupler U1, the first terminal of the resistor R2, and the first terminal of the capacitor C2 are connected to the resistor R... L The first terminals are all connected, and the resistor R L The second terminal and the capacitor C L The first terminal is connected to both the VOUT terminal; the capacitor C L The second end is connected to the second GND end.

5. An automatic switching optocoupler isolation circuit for a short-circuit current limiter according to claim 4, characterized in that, The resistor R L The resistance of the capacitor is 10KΩ, and the capacitor C L Its capacitance is 0.1 μF.

6. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 1, characterized in that, The optocoupler U1 is a TLP521 type optocoupler.

7. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 1, characterized in that, The optocoupler U1 is a TLP627 type optocoupler.

8. The automatic switching on / off optocoupler isolation circuit for a short-circuit current limiter according to claim 1, characterized in that, The short-circuit current limiter is powered by 220VAC mains power or 220VAC inverter power.

9. An automatic switching optocoupler isolation circuit for a short-circuit current limiter according to claim 1, characterized in that, The first power supply is a +24V power supply, and the second power supply is a +5V power supply.

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