Surge current protection circuit, surge protector, air switch and residual current circuit breaker

Abstract

The utility model relates to the technical field of surge circuit protection, in particular to a surge current protection circuit, a surge protector, an air switch and a residual-current circuit breaker. The surge current protection circuit comprises a three-phase input end, a three-phase output end, a first resistor, a second resistor, a third resistor, a first varistor, a second varistor, a third varistor, an A-phase output end, a B-phase output end and a C-phase output end. According to the anti-surge circuit, the first resistor, the second resistor and the third resistor are all winding type resistors, and the three winding type resistors and the three piezoresistors are combined to form the star-shaped anti-surge circuit. Therefore, as the surge current impact force of the winding type electrical impedance is high in reliability, and the surge current is firstly absorbed by the first resistor, the second resistor and the third resistor, the surge current energy impact of the voltage dependent resistor at the downstream can be shared, the service life of the voltage dependent resistor is prolonged, and the service life of the whole circuit or device is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of surge circuit protection, and in particular to a surge current protection circuit, a surge protector, an air switch, and a leakage circuit breaker. Background Art

[0002] Inrush current primarily occurs when electrical equipment is turned on. Due to the rapid charging of input filter capacitors, the peak current flowing into the power supply is significantly greater than the steady-state input current. Circuit anomalies such as electrostatic discharge, electromagnetic interference, electromagnetic pulses, and transient radiation can also cause inrush current. Inrush current values are significantly higher than the circuit's steady-state current, and high currents can damage equipment or trigger circuit breakers. Inrush current typically occurs in all devices with magnetic cores, such as transformers and industrial voltage supplies.

[0003] In order to reduce the damage of surge current to the equipment, a surge current protection circuit is provided in the related art. Figure 1 For a schematic diagram of the surge current protection circuit structure provided in the related art, please refer to Figure 1 As shown, the surge current protection circuit includes a three-phase power input terminal, a fourth varistor, a fifth varistor, a sixth varistor, and a three-phase power output terminal. Among them, the fourth varistor is connected in series between the A-phase power input terminal and the B-phase power input terminal, the fifth varistor is connected in series between the B-phase power input terminal and the C-phase power input terminal, and the sixth varistor is connected in series between the A-phase power input terminal and the C-phase power input terminal. In this way, the three varistor and the three-phase power input terminal constitute a surge current absorption circuit. During operation, for example, when a surge current is generated between the A-phase power input terminal and the B-phase power input terminal in the circuit, the surge current flows through the fourth varistor, causing the A-phase power input terminal and the B-phase power input terminal to be approximately short-circuited, and then the energy of the surge current is directly consumed by the internal resistance of the fourth varistor. Specifically, the surge current is released in the form of heat on the varistor, thereby achieving the purpose of surge current protection. However, after the surge current protection circuit in the related art has been operating for a period of time, the varistor will be damaged due to long-term current shock, resulting in a shortened service life of the varistor, thereby affecting the service life of the circuit or device. Utility Model Content

[0004] The present application provides a surge current protection circuit, a surge protector, an air switch and a leakage circuit breaker to solve the technical problem of short service life of the surge current protection circuit in the related art.

[0005] In a first aspect, the present application provides an inrush current protection circuit, the inrush current protection circuit including an A-phase input terminal, a B-phase input terminal, a C-phase input terminal, a first resistor, a second resistor, a third resistor, a first varistor, a second varistor, a third varistor, an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal;

[0006] The first end of the A-phase input terminal is used to receive the A-phase current signal, the second end of the A-phase input terminal is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the first varistor, and the second end of the first varistor is connected to the second end of the second varistor; the first end of the A-phase output terminal is connected to the second end of the first resistor, and the second end of the A-phase output terminal is used to output the A-phase current signal;

[0007] The first end of the B-phase input terminal is used to receive the B-phase current signal, the second end of the B-phase input terminal is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the second varistor, and the second end of the second varistor is connected to the second end of the third varistor; the first end of the B-phase output terminal is connected to the second end of the second resistor, and the second end of the B-phase output terminal is used to output the B-phase current signal;

[0008] The first end of the C-phase input terminal is used to receive the C-phase current signal, the second end of the C-phase input terminal is connected to the first end of the third resistor, and the second end of the third resistor is connected to the first end of the third varistor; the first end of the C-phase output terminal is connected to the second end of the third resistor, and the second end of the C-phase output terminal is used to output the C-phase current signal.

[0009] In some possible designs, the first resistor, the second resistor, and the third resistor are all wire-wound resistors.

[0010] In some possible designs, the diameters of the first varistor, the second varistor, and the third varistor are all smaller than 10 mm.

[0011] In some possible designs, the diameters of the first varistor, the second varistor, and the third varistor are all 7 mm.

[0012] In a second aspect, the present application further provides a surge protector, which includes the surge current protection circuit as described in any one of the above items.

[0013] In a third aspect, the present application further provides an air switch, which includes a surge current protection circuit as described in any one of the above items.

[0014] In a fourth aspect, the present application further provides a leakage circuit breaker, which includes the surge current protection circuit as described in any one of the above items.

[0015] The surge current protection circuit provided in accordance with the first aspect above includes a three-phase input terminal, a three-phase output terminal, a first resistor, a second resistor, a third resistor, a first varistor, a second varistor, a third varistor, an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal. In the present application, the first resistor, the second resistor, and the third resistor are all wire-wound resistors, and the wire-wound resistors and the varistor are combined to form a star-shaped surge protection circuit. In this way, since the wire-wound resistors have a high reliability in resisting the surge current impact, the surge current is first absorbed by the first resistor, the second resistor, and the third resistor. This can share the surge current energy impact of the downstream varistor, thereby increasing the service life of the varistor and thus ensuring the service life of the entire circuit or device.

[0016] The beneficial effects provided in the above-mentioned second aspect and the various possible designs of the above-mentioned second aspect can be referred to the beneficial effects brought about by the above-mentioned first aspect and the various possible implementation methods of the first aspect, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a surge current protection circuit provided in the related art;

[0018] Figure 2 A schematic diagram of the surge current protection circuit structure provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] In this application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a alone, b alone, or c alone can represent: a alone, b alone, c alone, a and b in combination, a and c in combination, b and c in combination, or a, b, and c in combination, where a, b, and c can be single or multiple. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0020] The directions or positional relationships indicated by terms such as "center", "longitudinal", "lateral", "up", "down", "left", "right", "front", and "back" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the present application.

[0021] The terms "connected" and "connect" should be interpreted broadly. For example, "connected" or "connected" in a circuit structure can refer not only to a physical connection, but also to an electrical connection or a signal connection. For example, it can be a direct connection, i.e., a physical connection, or an indirect connection through at least one intermediate component, as long as the circuit is interconnected. It can also refer to internal connectivity between two components. Signal connection can refer not only to signal connection through circuits but also to signal connection through media, such as radio waves. Those skilled in the art will understand the specific meanings of the above terms in this application on a case-by-case basis.

[0022] The main sources of surge current include power switches, relays, constant voltage drivers, magnetic component saturation, inductance, and electrostatic discharge. When designing and using electrical equipment, you should consider how to effectively protect the equipment from the harm caused by surge current.

[0023] Surge current can cause irreversible damage to electronic equipment and components, including burnout, damage, and reduced lifespan. It can also cause protective circuits to fail or overload, leading to instantaneous equipment damage and even fire. During circuit design and use, it's important to consider the hazards of surge current and implement appropriate protective measures.

[0024] To reduce the damage caused by inrush current to equipment, various protective measures can be implemented, such as capacitors, voltage regulators, transient voltage suppressors, and discharge tubes. These measures can effectively absorb or reduce the peak value of inrush current, thereby protecting equipment from damage. In summary, inrush current is primarily caused by the sudden change in current when electrical equipment is turned on, and its main harm is damage to electronic equipment and components. Therefore, appropriate protective measures should be implemented during circuit design and operation to reduce the impact of inrush current.

[0025] See Figure 1As shown, the surge current protection circuit in the related art includes an A-phase power input terminal A1, an A-phase power output terminal A2, a B-phase power input terminal B1, a B-phase power output terminal B2, a C-phase power input terminal C1, a C-phase power output terminal C2, a fourth varistor R4, a fifth varistor R5, and a sixth varistor R6. The A-phase power input terminal A1 is connected to the first end of the fourth varistor R4, the second end of the fourth varistor R4 is connected to the B-phase power input terminal B1, the B-phase power input terminal B1 is also connected to the first end of the fifth varistor R5, the second end of the fifth varistor R5 is connected to the C-phase power input terminal C1; the C-phase power input terminal C1 is connected to the first end of the sixth varistor R6, the second end of the sixth varistor R6 is connected to the C-phase power input terminal C1. Thus, the three varistors and the three-phase power input terminals form a surge current absorption circuit. Among them, during the operation of the circuit, when there is a surge current in the current signal input by a certain phase circuit, the corresponding varistor will absorb the surge current to protect the downstream circuit or components. Taking the case where there is a surge current at the A-phase power input terminal A1 as an example, when there is a surge current at the A-phase power input terminal A1, the surge current first flows through the fourth varistor R4. The fourth varistor R4 is activated under the action of the surge voltage, thereby operating in a low-impedance state, making the A-phase power input terminal A1 and the B-phase power input terminal B1 approximately short-circuited, and then the energy of the surge current is directly consumed through the internal resistance of the fourth varistor R4. Specifically, the surge current is released in the form of heat on the fourth varistor R4, thereby achieving the purpose of surge current protection. When a surge current is generated at the other phase power input terminals, a current loop will also be formed through the corresponding varistor circuit to consume the surge current, thereby protecting the circuit and maintaining the stability of the circuit. However, a disadvantage of the surge current protection circuit in the related art is that the varistor in the related art is directly impacted by the surge current, resulting in the varistor being damaged due to long-term current impact after the surge current protection circuit has been working for a period of time, resulting in a shortened service life of the varistor, thereby affecting the working life of the circuit or device.

[0026] In addition, in high-current application scenarios, in order to ensure that the varistor can withstand large current shocks, the size of the varistor generally selected needs to be large, resulting in a large volume of the entire surge current protection circuit. In this way, in scenarios where space is relatively limited, the surge current protection circuit cannot be laid out, resulting in limited application scenarios. For example, in order to withstand the impact of a 2KA surge current, or in order to withstand a surge current impact of a differential mode voltage of 4KV or a working mode voltage of 5KV, the varistor in a general surge current protection circuit will choose a varistor with a diameter of at least 14mm, such as a varistor with a model number of 14D821, so as to ensure that the varistor will not decay or be damaged rapidly under the impact of the surge current. After testing, if the varistor with a diameter of 14mm is replaced with a 7mm varistor in order to reduce the space occupied by the circuit, the 7mm varistor will be damaged after several surge current impacts, thereby affecting the circuit from being damaged by the surge current impact. Therefore, the surge current protection circuits in the related art cannot be applied to circuit scenarios with limited space. For example, in the prior art, a circuit breaker with three open poles only has a width of 48mm for arranging the surge current protection circuit. However, the surge current protection circuit provided in the related art includes three 14mm varistors and cannot be arranged in the circuit breaker. Therefore, the surge current protection circuits provided in the related art cannot be applied to circuit scenarios with limited space.

[0027] In order to overcome the deficiencies in the above-mentioned related art, the present application provides a surge current protection circuit, which includes a three-phase input terminal, a three-phase output terminal, a first resistor, a second resistor, a third resistor, a first varistor, a second varistor, a third varistor, an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal. In the present application, the first resistor, the second resistor, and the third resistor are all wire-wound resistors, and the above-mentioned wire-wound resistors and varistor are combined to form a star-shaped surge protection circuit. In this way, since the wire-wound resistors have a high reliability in resisting the surge current impact force, the surge current is first absorbed by the first resistor, the second resistor, and the third resistor, which can share the surge current energy impact of the downstream varistor, thereby increasing the service life of the varistor, thereby ensuring the service life of the entire circuit or device.

[0028] Figure 2 For a schematic diagram of the surge current protection circuit structure provided in the embodiment of the present application, please refer to Figure 2 As shown, the surge current protection circuit includes an A-phase input terminal A3, a B-phase input terminal B3, a C-phase input terminal C3, a first resistor R1, a second resistor R2, a third resistor R3, a first varistor R10, a second varistor R20, a third varistor R30, an A-phase output terminal A0, a B-phase output terminal B0, and a C-phase output terminal C0.

[0029] The first end of the A-phase input terminal A3 is used to receive the A-phase current signal, and the second end of the A-phase input terminal A3 is connected to the first end of the first resistor R1, the second end of the first resistor R1 is connected to the first end of the first piezoresistor R10, and the second end of the first piezoresistor R10 is connected to the second end of the second piezoresistor R20. The first end of the A-phase output terminal A0 is connected to the second end of the first resistor R1, and the second end of the A-phase output terminal A0 is used to output the A-phase current signal. The first end of the B-phase input terminal B3 is used to receive the B-phase current signal, and the second end of the B-phase input terminal B3 is connected to the first end of the second resistor R2, the second end of the second resistor R2 is connected to the first end of the second piezoresistor R20, and the second end of the second piezoresistor R20 is connected to the second end of the third piezoresistor R30. The first end of the B-phase output terminal B0 is connected to the second end of the second resistor R20, and the second end of the B-phase output terminal B0 is used to output the B-phase current signal. The first end of the C-phase input terminal C3 is used to receive the C-phase current signal, the second end of the C-phase input terminal C3 is connected to the first end of the third resistor R3, and the second end of the third resistor R3 is connected to the first end of the third varistor R30; the first end of the C-phase output terminal C0 is connected to the second end of the third resistor R3, and the second end of the C-phase output terminal C0 is used to output the C-phase current signal.

[0030] As can be seen, in the surge current protection circuit provided by this embodiment, a wire-wound resistor and a varistor are connected in series at each phase input terminal, forming a star-shaped surge protection circuit by combining these wire-wound resistors and varistor. Thus, because the wire-wound resistors are highly reliable in resisting surge current impact, when a surge current flows between any two phase input terminals, the surge current is first absorbed by the first resistor, the second resistor, and the third resistor. This can share the surge current energy impact of the downstream varistor, extend the service life of the varistor, and thus ensure the service life of the entire circuit or device.

[0031] Preferably, the first resistor R1, the second resistor R2, and the third resistor R3 in this embodiment are all wire-wound resistors, for example, 4.7 ohm, 2W wire-wound resistors. Figure 1As shown, for example, when there is a 2KA surge current between the A-phase input terminal A3 and the B-phase input terminal B3, the surge current first passes through the first resistor R1. Since the wound resistor has high impact resistance and reliability, the first resistor R1 first absorbs most of the surge current, and the remaining surge current flows through the first varistor R10. The first varistor R10 presents a low impedance state under the action of the surge current, so that the remaining surge current is absorbed when it flows through the first varistor R10, thereby completely absorbing the surge current in the circuit. In this way, since the impedance of the upstream first resistor R1 is small, it can share part of the energy impact of the downstream varistor, thereby extending the service life of the varistor. Among them, the first resistor R1 and the first varistor R1 both release the surge current in the form of heat.

[0032] In some embodiments, when there is still a surge current remainder after passing through the first varistor R1, the surge current remainder will continue to flow through the second varistor R20, and then continue to flow through the second resistor R2, so that the remaining surge current will continue to be absorbed by the second varistor R20 and the second resistor R2. This is equivalent to the four resistors of the first resistor R1, the second resistor R2, the first varistor R10, and the second varistor R20 sharing the surge current, thereby avoiding the impact of the surge current on various components and ensuring the working life of the circuit.

[0033] In some embodiments, based on the surge current protection circuit provided in the embodiments of the present application, due to the presence of the first resistor R1, the second resistor R2, and the third resistor R3, the first varistor R10, the second varistor R20, and the third varistor R30 can use varistors with relatively small diameters. For example, varistors with diameters less than 10 mm can be used, and the smaller varistors can withstand the impact requirements of the surge current, so that the overall volume of the surge current protection circuit is smaller and can be deployed and used in a small space.

[0034] Specifically, in some embodiments, the first varistor R10, the second varistor R20, and the third varistor R30 can all be varistors with a diameter of 7 mm, such as the varistor model 07D561. This reduces the overall size of the surge current protection circuit, allowing the surge current protection circuit to be applied to air switches or leakage circuit breakers with smaller widths. For example, the surge current protection circuit provided in this embodiment can be applied to leakage circuit breakers with a width of 48 mm, while meeting the volume requirements of small leakage circuit breakers for electronic circuit boards.

[0035] Based on the surge current protection circuits provided in the above embodiments, this embodiment provides a surge protector that includes the above-described surge current protection circuit. While providing surge current protection for circuits, this surge protector has a long service life and a small overall size, making it suitable for use in smaller circuit layout spaces.

[0036] Building on the surge current protection circuits provided in the above embodiments, this embodiment provides an air switch including the aforementioned surge current protection circuit. While providing surge current protection for circuits, this air switch has a long service life and a small overall size, making it suitable for use in smaller circuit layout spaces.

[0037] Building on the surge current protection circuits provided in the above embodiments, this embodiment provides a leakage current circuit breaker that includes the aforementioned surge current protection circuit. This leakage current circuit breaker not only provides surge current protection for circuits, but also has a long service life and a small overall size, making it suitable for use in smaller circuit layout spaces.

[0038] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A surge current protection circuit, characterized in that: It includes an A-phase input terminal, a B-phase input terminal, a C-phase input terminal, a first resistor, a second resistor, a third resistor, a first varistor, a second varistor, a third varistor, an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal; The first end of the A-phase input terminal is used to receive the A-phase current signal, the second end of the A-phase input terminal is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the first varistor, and the second end of the first varistor is connected to the second end of the second varistor; the first end of the A-phase output terminal is connected to the second end of the first resistor, and the second end of the A-phase output terminal is used to output the A-phase current signal; The first end of the B-phase input terminal is used to receive the B-phase current signal, the second end of the B-phase input terminal is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the second varistor, and the second end of the second varistor is connected to the second end of the third varistor; the first end of the B-phase output terminal is connected to the second end of the second resistor, and the second end of the B-phase output terminal is used to output the B-phase current signal; The first end of the C-phase input terminal is used to receive the C-phase current signal, the second end of the C-phase input terminal is connected to the first end of the third resistor, and the second end of the third resistor is connected to the first end of the third varistor; the first end of the C-phase output terminal is connected to the second end of the third resistor, and the second end of the C-phase output terminal is used to output the C-phase current signal.

2. The surge current protection circuit according to claim 1, characterized in that: The first resistor, the second resistor and the third resistor are all wire-wound resistors.

3. The surge current protection circuit according to claim 1 or 2, characterized in that: The diameters of the first varistor, the second varistor, and the third varistor are all less than 10 mm.

4. The surge current protection circuit according to claim 1 or 2, characterized in that: The diameters of the first varistor, the second varistor, and the third varistor are all 7 mm.

5. A surge protector, characterized in that: The invention comprises a surge current protection circuit as described in any one of claims 1 to 4.

6. An air switch, characterized in that: The invention comprises a surge current protection circuit as described in any one of claims 1 to 4.

7. A leakage circuit breaker, characterized in that: The invention comprises a surge current protection circuit as described in any one of claims 1 to 4.

Images