CN220042974U

CN220042974U - Protection circuit and extension socket

Info

Publication number: CN220042974U
Application number: CN202320398679.9U
Authority: CN
Inventors: 金奇
Original assignee: Anker Innovations Co Ltd
Current assignee: Anker Innovations Co Ltd
Priority date: 2023-03-02
Filing date: 2023-03-02
Publication date: 2023-11-17
Anticipated expiration: 2033-03-02

Abstract

The embodiment of the utility model discloses a protection circuit and a socket, wherein the protection circuit comprises a sampling circuit, a rectifying and filtering circuit, a comparison circuit and a switching circuit, the sampling circuit is connected on a live wire of the socket in series, the rectifying and filtering circuit is electrically connected with the output end of the sampling circuit, the first input end of the comparison circuit is electrically connected with the output end of the rectifying and filtering circuit, the second input end of the comparison circuit is connected with a reference voltage, the output end of the comparison circuit is used for outputting a disconnection control signal when the voltage of a direct current signal is higher than the reference voltage, the switching circuit is electrically connected with the output end of the comparison circuit, and the switching circuit is further used for connecting a zero line of the socket in series and disconnecting the zero line according to the disconnection control signal. The protection circuit can timely disconnect the zero line when the extension socket is in a working state of overload, stops the extension socket work, has a protection effect, improves the safety performance and the service life of the extension socket, and has simple circuit design and lower design cost.

Description

Protection circuit and extension socket

Technical Field

The utility model relates to the technical field of power supply, in particular to a protection circuit and a socket.

Background

Along with the continuous improvement of the living standard of people, more and more electric equipment and higher electric energy use amount are adopted. In the related art, a powered device is usually connected to a commercial power through a socket, so as to supply power to the powered device.

The applicant found in the process of implementing the related art that: the socket in the related art is easily burned out when in an overload working state.

Disclosure of Invention

The embodiment of the utility model provides a protection circuit and a socket, which are used for solving the problem that a socket is easy to burn out when the socket is in a working state of overload in the related art.

The embodiment of the utility model provides a protection circuit, which comprises:

the sampling circuit is used for being connected in series on a live wire of the socket and used for sampling an alternating current signal on the live wire;

the rectification filter circuit is electrically connected with the output end of the sampling circuit and is used for converting the alternating current signal into a smooth direct current signal;

the first input end of the comparison circuit is electrically connected with the output end of the rectifying and filtering circuit, the second input end of the comparison circuit is connected with a reference voltage, and the output end of the comparison circuit is used for outputting a disconnection control signal when the voltage of the direct current electric signal is higher than the reference voltage;

the switching circuit is electrically connected with the output end of the comparison circuit and is further used for being connected on the zero line of the socket in series and used for disconnecting the zero line according to the disconnection control signal.

According to the protection circuit, the electric signals on the fire wires of the extension socket are collected, the voltage of the collected electric signals is compared with the voltage of the reference electric signals, and when the voltage of the collected electric signals is higher than the voltage of the reference electric signals, the zero wires of the extension socket are disconnected. The electric signal on the live wire can reflect the working state of the extension socket, if the reference electric signal in the protection circuit is designed as follows: when the extension socket is in a working state of overload of load, the electric signal voltage on the live wire is higher than the reference electric signal voltage, so that when the extension socket is in the working state of overload of load, the protection circuit cuts off the zero line, cuts off the extension socket work, and plays a protection effect. The protection circuit can improve the safety performance of the extension socket and the service life of the extension socket, and is simple in circuit design and low in design cost.

The rectifying and filtering unit can convert alternating current electric signals into direct current electric signals and convert peak electric signals into smooth electric signals. For example, the rectifying and filtering unit may convert an ac sine wave signal collected on the live wire into a dc square wave signal, i.e. stabilize the voltage of the dc electrical signal at the first input end of the comparison circuit approximately around a certain value, so as to timely disconnect the neutral wire when the voltage around the stabilized value exceeds the reference voltage. Compared with the scheme that an electric signal with a larger variation range is input at the first input end of the comparison circuit, when the voltage of the changed electric signal is lower than the reference voltage for a certain period of time, the zero line is still conducted in the period of time, and when the voltage of the changed electric signal is higher than the reference voltage for another period of time, the zero line is disconnected in the period of time, and the power strip is disconnected more timely.

In some of these embodiments, the sampling circuit comprises:

a transformer comprising a primary winding and a secondary winding;

the primary winding is used for being connected to the live wire in series, and the secondary winding is electrically connected with the input end of the rectifying and filtering circuit.

Based on the embodiment, the mutual inductor can convert a larger electric signal on the live wire into a smaller electric signal for detection, so that the safety of operators and meters can be ensured.

In some of these embodiments, further comprising:

and the voltage stabilizing circuit is electrically connected with the second input end of the comparison circuit and is used for providing the reference voltage.

Based on the embodiment, the voltage stabilizing circuit can provide a reference voltage with higher precision and stability, and is beneficial to improving the accuracy of the comparison result of the comparison circuit.

In some of these embodiments, the voltage stabilizing circuit includes:

the anode of the voltage stabilizing tube is grounded, and the reference electrode of the voltage stabilizing tube is electrically connected with the second input end of the comparison circuit;

and one end of the first resistor is electrically connected with the cathode of the voltage stabilizing tube and the reference electrode of the voltage stabilizing tube, and the other end of the first resistor is electrically connected with a first power supply.

Based on the above embodiment, the voltage provided by the voltage stabilizing tube has better precision and temperature stability. The first resistor is a current limiting resistor and can provide an operating current for the voltage stabilizing tube.

In some of these embodiments, the comparison circuit comprises:

the inverting terminal of the operational amplifier is the first input terminal of the comparison circuit, the in-phase terminal of the operational amplifier is the second input terminal of the comparison circuit, the output terminal of the operational amplifier is the output terminal of the comparison circuit, the power supply terminal of the operational amplifier is electrically connected with a second power supply, and the grounding terminal of the operational amplifier is grounded;

one end of the second resistor is electrically connected with the same-phase end of the operational amplifier, and the other end of the second resistor is electrically connected with the output end of the operational amplifier;

and one end of the first capacitor is electrically connected with the second power supply, and the other end of the first capacitor is grounded.

Based on the above embodiment, the operational amplifier is an amplifier with a special coupling circuit and feedback, and the output end of the operational amplifier can be the result of mathematical operations such as addition, subtraction, differentiation, integration and the like of the input signal, so that the circuit design can be simplified. The second resistor is a feedback resistor of the operational amplifier, and can feed back the signal of the output end of the operational amplifier to the input end to form a feedback circuit. The first capacitor may be used to cancel noise in the power signal provided by the second power supply.

In some of these embodiments, the comparison circuit further comprises:

and one end of the third resistor is electrically connected with the reverse end of the operational amplifier, and the other end of the third resistor is electrically connected with the output end of the rectifying and filtering circuit.

Based on the above embodiment, the third resistor is a current limiting resistor, and the third resistor is disposed near the opposite end of the operational amplifier, which is beneficial to smooth operation of the operational amplifier.

In some of these embodiments, the rectifying and filtering circuit includes:

the rectification unit is electrically connected with the output end of the sampling circuit;

and the filtering unit is electrically connected with the output end of the rectifying unit and the first input end of the comparison circuit.

Based on the above embodiment, the rectifying unit is arranged in front of the filtering unit, so that the filtering capacitor can work in a pulsating direct current environment, and the capacitor is charged and discharged in the direct current circuit to change the pulsating direct current into smooth ripple direct current with small variation amplitude. Therefore, the electrolytic capacitor with high capacity and polarity requirement can be selected as the filter capacitor, the energy storage capacity of the capacitor is fully exerted, and the filter effect is ensured.

In some embodiments, the rectifying unit includes a diode, an anode of the diode is electrically connected to the output terminal of the sampling circuit, and a cathode of the diode is electrically connected to the first input terminal of the comparing circuit;

the filtering unit comprises a second capacitor and a fourth resistor, one end of the second capacitor is electrically connected with the cathode of the diode, and the other end of the second capacitor is electrically connected with the other end of the secondary winding; one end of the fourth resistor is electrically connected with the cathode of the diode, and the other end of the fourth resistor is electrically connected with the other end of the secondary winding and grounded.

Based on the embodiment, the rectifier unit adopts the diode to realize half-wave rectification, so that the wiring mode is simple and the cost is low. The filtering unit adopts resistance-capacitance filtering, the circuit design is simple, and the manufacturing cost is low.

In some of these embodiments, the switching circuit comprises:

the base electrode of the triode is electrically connected with the output end of the comparison circuit, and the emitting electrode of the triode is grounded;

one end of the fifth resistor is electrically connected with the collector electrode of the triode;

one end of a coil of the relay is electrically connected with the other end of the fifth resistor, the other end of the coil is electrically connected with a third power supply, and a switch of the relay is connected in series on the zero line;

and one end of the sixth resistor is electrically connected with the base electrode of the triode, and the other end of the sixth resistor is electrically connected with the emitter electrode of the triode.

Based on the embodiment, the switch circuit is designed to comprise the relay, and only the switch of the relay is connected in series with the zero line, so that when the switch of the relay is closed, the zero line directly conducts the closed switch, other components are not connected in series with the zero line, and the power supply of the power strip cannot be influenced. When the comparison circuit outputs a disconnection control signal, the triode is related to the disconnected switch, so that the coil of the relay does not pass through current, the switch of the relay is disconnected, the zero line is disconnected, and the extension socket cannot supply power for electric equipment.

In a second aspect, the present utility model provides a power strip, including:

a housing;

a substrate positioned in the housing; and

The protection circuit is arranged on the substrate.

The extension socket provided by the utility model comprises the protection circuit and has the advantages of high safety performance, long service life, lower design cost and the like.

Drawings

In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic block diagram of a protection circuit provided by a first embodiment of the present utility model;

fig. 2 is a schematic block diagram of a protection circuit provided by a second embodiment of the present utility model;

fig. 3 is a schematic block diagram of a protection circuit according to a third embodiment of the present utility model;

fig. 4 is a circuit schematic of the protection circuit shown in fig. 3;

fig. 5 is a schematic structural diagram of a power strip according to an embodiment of the present utility model.

Reference numerals illustrate: 10. a row of plugs; 100. a protection circuit; 110. a sampling circuit; u1, a mutual inductor; 120. a rectifying and filtering circuit; 121. a rectifying unit; d1, a diode; 122. a filtering unit; c2, a second capacitor; r4, a fourth resistor; 130. a comparison circuit; u2, an operational amplifier; r2, a second resistor; c1, a first capacitor; r3, a third resistor; 140. a switching circuit; q1, triode; r5, a fifth resistor; k1, a relay; r6, a sixth resistor; 150. a voltage stabilizing circuit; VR1, a voltage stabilizing tube; r1, a first resistor; vref, reference voltage; l, live wire; n, zero line; 200. a housing.

Detailed Description

In order to make the objects, technical solutions and advantages of the present utility model more apparent, the following detailed description of the embodiments of the present utility model will be given with reference to the accompanying drawings.

When the following description refers to the accompanying drawings, the same numbers in different drawings refer to the same or similar elements, unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the utility model. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the utility model as detailed in the accompanying claims.

Referring to fig. 1 to 4, an embodiment of the present utility model provides a protection circuit 100, where the protection circuit 100 is used in a power strip 10, and is used for cutting off electrical connection between the power strip 10 and electric equipment when the power strip 10 is in a load overload working state, so as to realize effective protection when the power strip 10 works abnormally, and improve safety performance and service life of the power strip 10.

Specifically, the protection circuit 100 is configured to collect an electrical signal on the live line L of the extension socket 10, compare the voltage of the collected electrical signal with the voltage of a reference electrical signal, and disconnect the neutral line N of the extension socket 10 when the voltage of the collected electrical signal is higher than the voltage of the reference electrical signal. The electrical signal on the live line L may reflect the working state of the extension socket 10, if the reference electrical signal in the protection circuit 100 is designed as follows: when the extension socket 10 is in a working state of overload, the voltage of the electric signal on the live wire L is higher than the voltage of the reference electric signal, so that when the extension socket 10 is in the working state of overload, the protection circuit 100 cuts off the zero line N, so that the extension socket 10 cannot supply power to electric equipment, and a protection effect is achieved.

More specifically, the protection circuit 100 includes a sampling circuit 110, a rectifying and filtering circuit 120, a comparing circuit 130, and a switching circuit 140. The sampling circuit 110 is connected in series to the live line L of the extension socket 10, and is used for sampling an ac signal on the live line L. The rectifying and filtering circuit 120 is electrically connected to an output end of the sampling circuit 110, and is configured to convert an ac electrical signal into a smoothed dc electrical signal. The first input end of the comparison circuit 130 is electrically connected to the output end of the rectifying and filtering circuit 120, the second input end of the comparison circuit 130 is connected to the reference voltage Vref, and the output end of the comparison circuit 130 is used for outputting a disconnection control signal when the voltage of the direct current signal is higher than the reference voltage Vref. The switch circuit 140 is electrically connected to the output end of the comparing circuit 130, and the switch circuit 140 is further configured to be connected in series to the neutral line N of the socket 10, for disconnecting the neutral line N according to the disconnection control signal. The protection circuit 100 of the present utility model has the advantages of simple design and low design cost.

The rectifying and filtering unit 122 may convert an ac electrical signal into a dc electrical signal, and convert a spike electrical signal into a smooth electrical signal. For example, the rectifying and filtering unit 122 may convert the ac sine wave signal collected on the live wire L into a dc square wave signal, that is, stabilize the voltage of the dc electrical signal at the first input end of the comparison circuit 130 approximately around a certain value, so as to timely disconnect the neutral wire N when the voltage around the stabilized value exceeds the reference voltage Vref. Compared with the case where an electrical signal with a larger variation range is input to the first input terminal of the comparison circuit 130, when the voltage of the varying electrical signal is lower than the reference voltage Vref for a certain period of time, the zero line N is still turned on for the certain period of time, and when the voltage of the varying electrical signal is higher than the reference voltage Vref for another period of time, the zero line N is turned off for the certain period of time, which is more timely.

It should be noted that, the output terminal of the comparing circuit 130 is further configured to output a turn-on control signal when the voltage of the dc signal is lower than the reference voltage Vref, and the switching circuit 140 is configured to turn on the zero line N according to the turn-on control signal. Specifically, when the power strip 10 is in a normal working state, the output end of the comparison circuit 130 outputs a conduction control signal, so that the zero line N is turned on, and the power strip 10 supplies power to the electric equipment.

Optionally, the sampling circuit 110 includes a transformer U1, a primary winding of the transformer U1 is connected in series to the live wire L, and a secondary winding of the transformer U1 is electrically connected to an input end of the rectifying and filtering circuit 120. The mutual inductor U1 can convert a larger electric signal on the live wire L into a smaller electric signal for detection, and can ensure the safety of operators and meters. The current transformer may be selected as the transformer U1, which is not limited in the embodiment of the present utility model. When the current transformer is selected as the transformer U1, the alternating current signal is an alternating current signal, and the direct current signal is a direct current signal.

Optionally, the protection circuit 100 further includes a voltage stabilizing circuit 150, where the voltage stabilizing circuit 150 is electrically connected to the second input terminal of the comparing circuit 130, for providing the reference voltage Vref. The voltage stabilizing circuit 150 can provide a reference voltage Vref with higher accuracy and more stable, which is beneficial to improving the accuracy of the comparison result of the comparison circuit 130.

Optionally, the voltage stabilizing circuit 150 includes a voltage stabilizing tube VR1 and a first resistor R1, the anode of the voltage stabilizing tube VR1 is grounded, and the reference electrode of the voltage stabilizing tube VR1 is electrically connected to the second input end of the comparing circuit 130; one end of the first resistor R1 is electrically connected with the cathode of the voltage stabilizing tube VR1 and the reference electrode of the voltage stabilizing tube VR1, and the other end is electrically connected with the first power supply. The voltage provided by the voltage stabilizing tube VR1 has better precision and temperature stability. The first resistor R1 is a limiting resistor and can provide an operating current for the voltage regulator VR 1.

In the embodiment of the utility model, the first power supply can be a 5V power supply. The voltage stabilizing tube VR1 can be TL431, and the TL431 has better precision and temperature stability. The stable voltage generated by TL431 can be set between 2.5 and 36V through two external resistors, and the use is flexible. In the embodiment of the utility model, the cathode and the reference electrode of the TL431 are short-circuited and then are connected with a first power supply through a first resistor R1, and the anode is directly grounded, so that a 2.5V precise reference voltage source with good temperature stability can be formed.

Optionally, the comparison circuit 130 includes an operational amplifier U2, a second resistor R2 and a first capacitor C1, an inverting terminal of the operational amplifier U2 is a first input terminal of the comparison circuit 130, an in-phase terminal of the operational amplifier U2 is a second input terminal of the comparison circuit 130, an output terminal of the operational amplifier U2 is an output terminal of the comparison circuit 130, a power supply terminal of the operational amplifier U2 is electrically connected to a second power supply, and a ground terminal of the operational amplifier U2 is grounded; one end of the second resistor R2 is electrically connected with the same-phase end of the operational amplifier U2, and the other end of the second resistor R2 is electrically connected with the output end of the operational amplifier U2; one end of the first capacitor C1 is electrically connected with the second power supply, and the other end of the first capacitor C is grounded.

In the embodiment of the utility model, the operational amplifier U2 is an amplifier with a special coupling circuit and feedback, and the output end of the operational amplifier can be the result of mathematical operations such as addition, subtraction, differentiation, integration and the like of an input signal, so that the circuit design can be simplified. The second resistor R2 is a feedback resistor of the operational amplifier U2, and can feedback the signal of the output end of the operational amplifier U2 to the input end to form a feedback circuit. The first capacitor C1 may be used to cancel noise in the power signal provided by the second power supply. In the embodiment of the utility model, the second power supply can be a 5V power supply. The operational amplifier U2 may be an LM393A.

Optionally, the comparing circuit 130 further includes a third resistor R3, where one end of the third resistor R3 is electrically connected to the inverting terminal of the operational amplifier U2, and the other end is electrically connected to the output terminal of the rectifying and filtering circuit 120. The third resistor R3 is a current limiting resistor, and the third resistor R3 is arranged close to the reverse end of the operational amplifier U2, so that smooth operation of the operational amplifier U2 is facilitated. It should be noted that, the comparison circuit 130 may not include the third resistor R3, but a resistor is disposed in the rectifying and filtering circuit 120 and connected in series with the opposite end of the operational amplifier U2, which is not described herein.

Optionally, the rectifying and filtering circuit 120 includes a rectifying unit 121 and a filtering unit 122, where the rectifying unit 121 is electrically connected to an output end of the sampling circuit 110; the filtering unit 122 is electrically connected to the output terminal of the rectifying unit 121 and the first input terminal of the comparing circuit 130. The rectifying unit 121 is disposed before the filtering unit 122, so that the filtering capacitor can work in a pulsating direct current environment, and the capacitor is charged and discharged in the direct current circuit to change the pulsating direct current into a smooth ripple direct current with small variation amplitude. Therefore, the electrolytic capacitor with high capacity and polarity requirement can be selected as the filter capacitor, the energy storage capacity of the capacitor is fully exerted, and the filter effect is ensured.

Optionally, the rectifying unit 121 includes a diode D1, an anode of the diode D1 is electrically connected to the output terminal of the sampling circuit 110, and a cathode of the diode D1 is electrically connected to the first input terminal of the comparing circuit 130. The diode D1 can realize half-wave rectification, and the wiring mode is simple and has lower cost. Note that, the rectifying unit 121 may also adopt full-wave rectification, bridge rectification, or the like, which is not limited in the embodiment of the present utility model.

Optionally, the filtering unit 122 includes a second capacitor C2 and a fourth resistor R4, wherein one end of the second capacitor C2 is electrically connected to the cathode of the diode D1, and the other end is electrically connected to the other end of the secondary winding; one end of the fourth resistor R4 is electrically connected with the cathode of the diode D1, and the other end of the fourth resistor R is electrically connected with the other end of the secondary winding and grounded. The filtering unit 122 selects the resistor-capacitor filtering, so that the circuit design is simple and the manufacturing cost is low.

Optionally, the switch circuit 140 includes a transistor Q1, a fifth resistor R5, a relay K1, and a sixth resistor R6, where a base electrode of the transistor Q1 is electrically connected to an output end of the comparison circuit 130, and an emitter electrode of the transistor Q1 is grounded; one end of the fifth resistor R5 is electrically connected with the collector electrode of the triode Q1; one end of a coil of the relay K1 is electrically connected with the other end of the fifth resistor R5, the other end of the coil is electrically connected with a third power supply, and a switch of the relay K1 is connected in series on the zero line N; one end of the sixth resistor R6 is electrically connected with the base electrode of the triode Q1, and the other end of the sixth resistor R6 is electrically connected with the emitter electrode of the triode Q1. Wherein, the third power supply can select 12V power supply.

The switch circuit 140 is designed to include the relay K1, and only the switch of the relay K1 is connected in series to the zero line N, so when the switch of the relay K1 is closed, the zero line N is directly conducted through the closed switch, and other components are not connected in series to the zero line N, so that the power supply of the power strip cannot be affected. The switch circuit 140 is designed to include a triode Q1, and when the extension socket 10 is in a working state of overload, the comparison circuit 130 outputs a disconnection control signal, that is, the comparison circuit 130 outputs a low potential, at this time, the triode Q1 corresponds to a disconnected switch, so that no current passes through a coil of the relay K1, the switch of the relay K1 is disconnected, the zero line N is disconnected, and the extension socket 10 cannot supply power to electric equipment, thereby realizing over-power protection. When the power strip 10 is in a normal working state, the comparison circuit 130 outputs a conduction control signal, that is, the comparison circuit 130 outputs a high potential, at this time, the triode Q1 is related to conduction, so that the coil of the relay K1 is conducted, the switch of the relay K1 is attracted, the zero line N is conducted, and the power strip 10 can supply power to electric equipment.

Preferably, when the comparison circuit 130 outputs the on control signal, the transistor Q1 is in a saturated state. In saturation, the transistor Q1 corresponds to a closed switch, and the voltage between the collector and the emitter of the transistor Q1 is very small.

At present, with the fast charging Power of the extension socket 10 and the built-in PD (one of the current fast charging protocols) becoming larger, when the extension socket 10 and the PD are fast charged and simultaneously fully loaded, the total Power is easy to exceed the rated value, resulting in the reduction of the product safety performance and the service life.

In a second aspect, referring to fig. 5, the present utility model provides a power strip 10, where the power strip 10 is a power distribution device for converting one input of a power source into multiple outputs, so as to be capable of adapting to the requirement of multiple devices for simultaneously using power.

The extension socket 10 includes a housing, a substrate and the protection circuit 100, where the substrate is located in the housing, and the protection circuit 100 is disposed on the substrate. The extension socket 10 of the utility model, comprising the protection circuit 100, has the advantages of high safety performance, long service life, lower design cost and the like.

The substrate is a carrier of the protection circuit 100, so that the stability of the circuit structure of the protection circuit 100 can be ensured, and stable installation in the housing can be realized. Alternatively, the substrate may be a snap connection, a screw connection, or the like between the shells, which is not limited in the embodiment of the present utility model. Optionally, the substrate may be attached to an inner wall surface of the housing, so as to improve stability of the substrate in mounting the housing.

In the description of the present utility model, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art. Furthermore, in the description of the present utility model, unless otherwise indicated, "a plurality" means two or more. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship.

The foregoing disclosure is illustrative of the present utility model and is not to be construed as limiting the scope of the utility model, which is defined by the appended claims.

Claims

1. A protection circuit, comprising:

the switching circuit is electrically connected with the output end of the comparison circuit and is further used for being connected in series with the zero line of the socket and used for disconnecting the zero line according to the disconnection control signal;

the comparison circuit comprises an operational amplifier, the inverting end of the operational amplifier is the first input end of the comparison circuit, the in-phase end of the operational amplifier is the second input end of the comparison circuit, the output end of the operational amplifier is the output end of the comparison circuit, the power end of the operational amplifier is electrically connected with a second power supply, and the grounding end of the operational amplifier is grounded.

2. The protection circuit of claim 1, wherein the sampling circuit comprises:

a transformer comprising a primary winding and a secondary winding;

3. The protection circuit of claim 1, further comprising:

4. The protection circuit of claim 3, wherein the voltage stabilizing circuit comprises:

5. The protection circuit of claim 1, wherein the comparison circuit further comprises:

6. The protection circuit of claim 5, wherein the comparison circuit further comprises:

7. The protection circuit according to claim 2, wherein the rectifying and filtering circuit includes:

8. The protection circuit of claim 7, wherein the rectifying unit comprises a diode, an anode of the diode is electrically connected to the output terminal of the sampling circuit, and a cathode of the diode is electrically connected to the first input terminal of the comparison circuit;

9. The protection circuit of claim 1, wherein the switching circuit comprises:

10. A strip comprising:

a housing;

a substrate positioned in the housing; and

The protection circuit of any one of claims 1 to 9, provided on the substrate.