Protection circuit of residual current operated circuit breaker

Abstract

The embodiment of the utility model discloses a protection circuit of a residual current operated circuit breaker. The protection circuit comprises a mutual inductor, a primary winding of the mutual inductor is a main loop, and a secondary winding of the mutual inductor comprises a first coupling node and a second coupling node; a first output node and a second output node, the first output node being coupled to the first coupling node; the second output node is coupled with the second coupling node; a bidirectional transient suppression diode coupled between the first coupling node and the second coupling node; the first end of the first resistor is coupled with the first coupling node, and the second end of the first resistor is coupled with the first output node; and a tripping mechanism coupled between the first output node and the second output node. The circuit board has the advantages that the electric leakage action time is short, false tripping of surge signals can be prevented, and components of the circuit board are simple.

Description

Technical Field

[0001] The present application relates to the field of low-voltage electrical appliances, and in particular to a protection circuit for a residual current operated circuit breaker. Background Art

[0002] In the terminal power supply system, the surge instantaneous residual current generated by the equipment with grounding capacitors and inductors at startup, the instantaneous overvoltage caused by lightning, the system operation overvoltage, the high-frequency leakage current, the system asynchronism, etc. may cause the residual current operated circuit breaker (RCBO) to malfunction. The existing surge-proof electromagnetic residual current circuit breakers are all delayed solution products with a long product action time. The basic implementation principle is to charge the energy storage capacitor after limiting filtering and rectifying the leakage induction signal of the secondary winding of the transformer. After the charging voltage reaches the conduction threshold of the voltage comparator, the thyristor or MOS tube is triggered to turn on, and the current flows through the relay coil to drive the RCBO mechanism to operate. The existing surge-proof electromagnetic residual current circuit breakers have the disadvantages of long leakage action time (>150ms), complex circuit board components, and high cost. Utility Model Content

[0003] The main purpose of the utility model is to provide a protection circuit of a residual current operated circuit breaker, aiming to solve the above-mentioned problems existing in the prior art.

[0004] In order to achieve the above object, the utility model provides a protection circuit of a residual current operated circuit breaker, characterized in that it includes:

[0005] A mutual inductor, wherein the primary winding of the mutual inductor is a main loop, and the secondary winding of the mutual inductor comprises a first coupling node and a second coupling node;

[0006] a first output node and a second output node, the first output node being coupled to the first coupling node; the second output node being coupled to the second coupling node;

[0007] a bidirectional transient suppression diode coupled between the first coupling node and the second coupling node;

[0008] a first resistor, wherein a first end of the first resistor is coupled to the first coupling node, and a second end of the first resistor is coupled to the first output node;

[0009] A tripping mechanism is coupled between the first output node and the second output node.

[0010] In some embodiments,

[0011] The conduction voltage of the bidirectional transient suppression diode is 5V-12V.

[0012] In some embodiments,

[0013] The resistance of the first resistor is 27Ω-50Ω.

[0014] In some embodiments,

[0015] The protection circuit further comprises:

[0016] a first diode coupled between the first coupling node and the second coupling node;

[0017] A second diode is coupled between the first coupling node and the second coupling node and is in the opposite direction to the first diode.

[0018] In some embodiments,

[0019] The first diode and the second diode are silicon diodes.

[0020] In some embodiments,

[0021] The protection circuit further comprises:

[0022] a first capacitor, wherein a first end of the first capacitor is coupled to a second end of the first resistor, and a second end of the first capacitor is coupled to the first output node;

[0023] The second capacitor is coupled between the first output node and the second output node.

[0024] In some embodiments,

[0025] The capacitance ratio of the first capacitor to the second capacitor is 2-5.

[0026] In some embodiments,

[0027] The capacitance of the first capacitor is 10μF-68μF;

[0028] The capacitance of the second capacitor is 5 μF-33 μF.

[0029] In some embodiments,

[0030] The tripping mechanism includes an electromagnetic relay and an operating component;

[0031] The number of turns of the coil of the electromagnetic relay is 550-650.

[0032] In some embodiments,

[0033] The turns ratio of the secondary winding to the primary winding of the mutual inductor is 30-40.

[0034] The protection circuit and residual current operated circuit breaker proposed in the present application, when a transient surge current appears on the main circuit side to be protected, the secondary winding of the transformer induces a transient overvoltage signal. If the induced voltage signal exceeds the conduction voltage of the bidirectional transient suppression diode TVS connected in parallel at both ends of the secondary winding, the bidirectional transient suppression diode TVS will be quickly turned on, clamping the amplitude of the induced voltage signal below the conduction voltage drop of the bidirectional transient suppression diode TVS, and then further suppressing and attenuating the induced voltage signal through the first current limiting resistor R1 connected in series at the rear end, so that the energy of the transient surge induced signal is insufficient to drive the electromagnetic relay in the tripping mechanism to operate. The bidirectional transient suppression diode TVS and the first current limiting resistor R1 work together to achieve the effect of preventing false tripping of surge signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0036] The methods, systems and / or programs in the accompanying drawings will be further described according to exemplary embodiments. These exemplary embodiments will be described in detail with reference to the drawings. These exemplary embodiments are non-limiting exemplary embodiments, wherein reference numerals represent similar mechanisms in the various views of the accompanying drawings.

[0037] Figure 1 A schematic diagram of the environment structure when the residual current operated circuit breaker involved in some embodiments of the present application is applied to surge protection of the main circuit;

[0038] Figure 2 This is a circuit structure diagram of a residual current operated circuit breaker involved in some embodiments of the present application.

[0039] Icon: 1-main circuit, 2-transformer, 3-secondary winding, 4-protection circuit, 5-electromagnetic relay, 6-operating component, CT1-first coupling node, CT2-second coupling node, EMR+-first output node, EMR--second output node, D1-first diode, D2-second diode, R1-first resistor, C1-first capacitor, C2-second capacitor. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of this application, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, if the terms "first", "second", etc. appear in the description of this application, they are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0044] In addition, if the terms "horizontal" or "vertical" appear in the description of this application, it does not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0045] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0046] Figure 11 is a schematic diagram of the environment structure when the residual current operated circuit breaker in the embodiment of the present application is applied to the surge protection of the main circuit 1; Figure 2 yes Figure 1 Please refer to the circuit diagram of the residual current operated circuit breaker. Figure 1 The residual current operated circuit breaker in this embodiment includes a protection circuit 4.

[0047] The protection circuit 4 in this embodiment includes a transformer 2 and a tripping mechanism. The transformer 2 can be a zero-sequence current transformer. The three-phase live wires L1, L2, L3 and the neutral wire N pass through the transformer 2, and the part passing through the transformer 2 serves as the primary winding. It should be noted that the residual current operated circuit breaker in this embodiment can also be a 1PN circuit breaker, that is, a single-phase live wire and a neutral wire can pass through the transformer 2. The two ends of the secondary winding 3 of the transformer 2 serve as the output ends of the transformer 2, which are the first coupling node CT1 and the second coupling node CT2, respectively. The protection circuit 4 plays the role of limiting filtering, and the first output node EMR+ and the second output node EMR- of the protection circuit 4 are coupled to the tripping mechanism. Specifically, the tripping mechanism includes an electromagnetic relay 5 and an operating component 6. The first output node EMR+ and the second output node EMR- are respectively coupled to the two ends of the electromagnetic relay 5.

[0048] Please refer to Figure 2 In this embodiment, the protection circuit 4 further includes a bidirectional transient suppression diode TVS, a first diode D1, a second diode D2, a first resistor R1, a first capacitor C1, and a second capacitor C2.

[0049] The first coupling node CT1 is coupled to the first output node EMR+ of the protection circuit 4 through the first resistor R1 and the first capacitor C1 in sequence. The second coupling node CT2 is directly coupled to the second output node EMR- of the protection circuit 4. The second capacitor C2 is coupled between the first output node EMR+ and the second output node EMR- of the protection circuit 4. Optionally, the first capacitor C1 and the second capacitor C2 are tantalum capacitors.

[0050] The bidirectional transient suppression diode TVS, the first diode D1 and the second diode D2 are connected in parallel and coupled between the first output node EMR+ and the second output node EMR-. The first diode D1 and the second diode D2 are in reverse: the anode of the first diode D1 and the cathode of the second diode D2 are both coupled to the first output node EMR+, and the cathode of the first diode D1 and the anode of the second diode D2 are both coupled to the second output node EMR-. Optionally, the first diode D1 and the second diode D2 are silicon diodes, and their conduction voltage is 0.7V.

[0051] The leakage working principle of the residual current operated circuit breaker is as follows:

[0052] When leakage current occurs in the main circuit 1, the primary winding generates residual magnetic flux, which is coupled to the secondary winding 3 through the mutual inductor 2, thereby generating an induced voltage at both ends of the secondary winding 3. The induced voltage flows through the coil of the electromagnetic relay 5 after passing through the protection circuit 4 and generates an induced magnetic field, wherein the first diode D1 and the second diode D2 clamp the voltage between the first output node EMR+ and the second output node EMR-, thereby preventing the back-end circuit components from being damaged due to excessive voltage. After the induced magnetic field is offset by the internal magnetic field of the electromagnetic relay 5, the electromagnetic relay 5 releases the top rod and drives the operating component 6 to trip, and the moving contact and the static contact in the operating component 6 are separated, thereby cutting off the main circuit 1.

[0053] The surge protection tripping principle of the residual current operated circuit breaker is as follows:

[0054] When a transient surge current appears in the main circuit 1, the secondary winding 3 of the transformer 2 induces a transient overvoltage signal. If the voltage of the induced signal exceeds the conduction voltage of the bidirectional transient suppression diode TVS connected in parallel at both ends of the secondary winding 3, the bidirectional transient suppression diode TVS will quickly turn on. Since the surge duration is relatively short, and the conduction time of the first diode D1 and the second diode D2 is greater than the conduction time of the bidirectional transient suppression diode TVS, the first diode D1 and the second diode D2 will not be able to turn on in time, and the voltage amplitude of the induced signal will be clamped below the conduction voltage drop of the bidirectional transient suppression diode TVS. The current-limiting first resistor R1 connected in series at the rear end further suppresses and attenuates the induced signal, so that the energy of the induced signal is insufficient to drive the electromagnetic relay 5 in the tripping mechanism to operate. The bidirectional transient suppression diode TVS and the current-limiting first resistor R1 work together to prevent the surge signal from being tripped by mistake.

[0055] The following table shows the test results of surge false operation value of residual current operated circuit breaker after using different parameters for each component. " / " in the table means that the component is not used. In the final result, the larger the surge false operation value, the better the surge protection against false tripping of the residual current operated circuit breaker.

[0056]

[0057]

[0058] According to the above table, preferably, the ratio of the number of turns N2 of the secondary winding 3 of the mutual inductor 2 to the number of turns N1 of the primary winding is 30-40. According to the principle of conservation of energy and the principle of mutual inductance of the transformer, the voltage U1 at both ends of the primary winding and the voltage U2 at both ends of the secondary winding 3 satisfy: U1 / N1=U2 / N2. When U1 and N1 remain unchanged, the number of turns N2 of the secondary winding 3 is increased, and the corresponding U2 also rises synchronously. The more the energy of the surge induction signal is attenuated after being clamped by the bidirectional transient suppression diode TVS, the more the surge induction signal can be effectively suppressed. According to experimental verification, N2 / N1 is more reasonable between 30-40. If the ratio is too low, the suppression effect cannot be achieved. If the ratio is too high, the normal leakage induction signal will be attenuated too much after being limited by the first diode D1 and the second diode D2, and the electromagnetic relay 5 cannot be reliably driven to operate, which in turn causes the residual current action value of the circuit breaker to be too large, and the standard requirements of the residual current action circuit breaker cannot be met.

[0059] According to the above table, preferably, the on-voltage of the bidirectional transient suppression diode TVS is 5V-12V. If the on-voltage of the bidirectional transient suppression diode TVS is too low, the normal leakage induction signal will be filtered out, resulting in the pulsating DC characteristics of the circuit breaker being unqualified. If the on-voltage is too high, the surge induction signal cannot be effectively clamped and suppressed.

[0060] According to the above table, preferably, the resistance of the first resistor R1 is 27Ω-50Ω. If the resistance of the first resistor R1 is too large, the normal sensing signal will be severely attenuated, and if the resistance is too small, it will not have the effect of limiting the current and dividing the voltage of the surge sensing signal.

[0061] According to the above table, preferably, the number of turns n of the coil in the electromagnetic relay 5 is 550-650. Increasing the number of turns n of the coil of the electromagnetic relay 5 is helpful to further suppress the surge induction signal: the more turns n, the greater the inductive reactance of the coil of the electromagnetic relay 5, and the greater the impedance under the surge transient current, but due to the space limitation of the electromagnetic relay 5 shell and its own impedance, the number of turns n of the coil should not be too much.

[0062] According to the above table, preferably, the capacitance of the first capacitor C1 is 10μF-68μF, the capacitance of the second capacitor C2 is 5μF-33μF, and the capacitance ratio of the first capacitor C1 to the second capacitor C2 is 2-5. Since the induction signal coupled by the mutual inductor 2 from the main circuit 1 is weak, the first capacitor C1 and the second capacitor C2 can match the inductance of the secondary winding 3 and the coil of the electromagnetic relay 5, thereby reducing the impedance of the overall loop and making it easier for the electromagnetic relay 5 to respond to leakage. The capacitance of the first capacitor C1 and the second capacitor C2 decreases with the increase of the number of turns N2 of the secondary winding 3 and the number of turns n of the coil of the electromagnetic relay 5. The specific capacitance is determined by loop impedance matching to meet the leakage characteristics requirements of the AC and pulsating DC of the residual current operated circuit breaker.

[0063] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A protection circuit (4) for a residual current operated circuit breaker, It is characterized in that include: A mutual inductor (2), wherein the primary winding of the mutual inductor (2) is a main loop, and the secondary winding (3) of the mutual inductor (2) comprises a first coupling node (CT1) and a second coupling node (CT2); A first output node (EMR+) and a second output node (EMR-), wherein the first output node (EMR+) is coupled to the first coupling node (CT1); and the second output node (EMR-) is coupled to the second coupling node (CT2); a bidirectional transient suppression diode (TVS), coupled between the first coupling node (CT1) and the second coupling node (CT2); a first resistor (R1), wherein a first end of the first resistor (R1) is coupled to the first coupling node (CT1), and a second end of the first resistor (R1) is coupled to the first output node (EMR+); The tripping mechanism is coupled between the first output node (EMR+) and the second output node (EMR-).

2. The protection circuit (4) as claimed in claim 1, It is characterized in that The conduction voltage of the bidirectional transient voltage suppressor (TVS) diode is 5V-12V.

3. The protection circuit (4) according to claim 1 or 2, It is characterized in that The resistance of the first resistor (R1) is 27Ω-50Ω.

4. The protection circuit (4) as claimed in claim 1, It is characterized in that The protection circuit (4) further comprises: a first diode (D1) coupled between the first coupling node (CT1) and the second coupling node (CT2); The second diode (D2) is coupled between the first coupling node (CT1) and the second coupling node (CT2) and is in the opposite direction to the first diode (D1).

5. The protection circuit (4) as claimed in claim 4, It is characterized in that The first diode (D1) and the second diode (D2) are silicon diodes.

6. The protection circuit (4) as claimed in claim 1, It is characterized in that The protection circuit (4) further comprises: a first capacitor (C1), wherein a first end of the first capacitor (C1) is coupled to a second end of the first resistor (R1), and a second end of the first capacitor (C1) is coupled to the first output node (EMR+); The second capacitor (C2) is coupled between the first output node (EMR+) and the second output node (EMR-).

7. The protection circuit (4) as claimed in claim 6, It is characterized in that The capacitance ratio of the first capacitor (C1) to the second capacitor (C2) is 2-5.

8. The protection circuit (4) as claimed in claim 7, It is characterized in that The capacitance of the first capacitor (C1) is 10μF-68μF; The capacitance of the second capacitor (C2) is 5μF-33μF.

9. The protection circuit (4) as claimed in claim 8, It is characterized in that The tripping mechanism comprises an electromagnetic relay (5) and an operating component (6); The number of turns of the coil of the electromagnetic relay (5) is 550-650.

10. The protection circuit (4) according to any one of claims 1 to 2 and 4 to 9, It is characterized in that The turns ratio of the secondary winding (3) to the primary winding of the mutual inductor (2) is 30-40.

Images