Shunt trip unit and circuit breaker with it

Abstract

This utility model discloses a shunt trip unit and a circuit breaker having the same. The shunt trip unit includes a voltage control system and a shunt coil connected to a power supply. The control system includes a step-down circuit, a MOSFET, a capacitor, a drive coil, and a switch contact controlled by the drive coil. The input terminal of the step-down circuit is connected to the power supply, and the output terminal is connected to the coil. The switch contact is connected between the power supply and the coil. The drive coil is connected to the output terminal of the step-down circuit. The source of the MOSFET is connected to the drive coil, the drain is connected to the power supply, and the gate is connected to the capacitor. The capacitor is connected to the output terminal of the step-down circuit. The voltage control system has a first mode and a second mode. In the first mode, a closed circuit is formed between the power supply and the shunt coil. In the second mode, a closed circuit is formed between the power supply, the step-down circuit, and the shunt coil, and the coil can be continuously energized without burning out.

Description

Technical Field

[0001] This utility model relates to a shunt trip device and a circuit breaker having the same. Background Technology

[0002] The shunt trip unit is a crucial component of a circuit breaker, allowing operators to remotely trip the circuit breaker. Typically, a shunt trip unit includes a shunt coil and a trip push rod driven by the coil. To prevent the shunt coil from burning out, a microswitch is usually connected in series with it. After the circuit breaker trips, the microswitch opens to cut off the current to the coil; when the circuit breaker recloses, the microswitch closes again. This configuration can easily lead to the circuit breaker accidentally reclosing, posing a safety hazard. Utility Model Content

[0003] The purpose of this invention is to provide a new shunt trip device.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is: a shunt trip unit connected to a power supply, comprising a shunt coil and a voltage control system, wherein the shunt coil has a first conductive terminal for input current and a second conductive terminal for output current, the second conductive terminal being connected to the power supply, and the voltage control system comprising:

[0005] A step-down circuit, wherein the input terminal of the step-down circuit is connected to the power supply, the output terminal of the step-down circuit is connected to the first conductive terminal, and the voltage at the output terminal of the step-down circuit is lower than the voltage at the input terminal;

[0006] A switching module includes a drive coil and a switch contact controlled by the drive coil, the switch contact being connected between the power supply and the first conductive terminal, and the drive coil being connected to the output terminal of the step-down circuit;

[0007] A MOS transistor, wherein the source of the MOS transistor is connected to the driving coil, and the drain of the MOS transistor is connected to the power supply;

[0008] A capacitor is connected to the output terminal of the step-down circuit and to the gate of the MOS transistor.

[0009] The voltage control system has a first mode and a second mode. In the first mode, the MOSFET is turned on, a first closed circuit is formed between the power supply, the step-down circuit and the drive coil, the switch contacts are closed, and a second closed circuit is formed between the power supply and the shunt coil. In the second mode, the capacitor is fully charged, the MOSFET is turned off, the switch contacts are open, and a third closed circuit is formed between the power supply, the step-down circuit and the shunt coil.

[0010] In some embodiments, the voltage control system includes an operational amplifier disposed between the output of the buck circuit and the capacitor.

[0011] In some embodiments, the switching module is an electromagnetic relay. In some embodiments, the shunt coil is connected in parallel with a diode. In some embodiments, the drive coil is connected in parallel with a diode.

[0012] In some embodiments, the step-down circuit employs a power supply chip, the input terminal of which is connected to the power supply.

[0013] In some embodiments, a trip unit body is included, the trip unit body comprising:

[0014] A housing, the housing having an internal cavity, and the shunt coil disposed in the internal cavity;

[0015] A tripping push rod is rotatably disposed in the middle of the housing. The tripping push rod has a first side and a second side located on opposite sides. The first side is provided with a cooperating component that engages with the shunt coil to drive the first side to rotate under the electromagnetic force of the shunt coil. The tripping push rod has an initial position and a tripping position. When in the initial position, the second side is retracted relative to the housing. When in the tripping position, the second side is moved away from the housing.

[0016] When the control system is in the second mode, the tripping push rod remains in the tripping position.

[0017] In some embodiments, the shunt trip unit further includes a control box, and the voltage control system is disposed within the control box;

[0018] The control box has four terminals, two of which are connected to the power supply, and the other two are connected to the first conductive terminal and the second conductive terminal, respectively.

[0019] In some embodiments, the trip unit body includes:

[0020] A micro switch is disposed in the accommodating cavity;

[0021] An auxiliary push rod is rotatably disposed in the middle of the housing. The auxiliary push rod has a trigger part and a drive part disposed on opposite sides. At least part of the drive part extends to the outside of the housing. The micro switch is located on the movement path of the trigger part.

[0022] The second elastic element is used to provide the force required to drive the auxiliary push rod to rotate.

[0023] In some embodiments, the trip unit body includes a first elastic element for providing the force required to move the trip push rod to the initial position.

[0024] In some embodiments, the mating member is an iron core fixed to the first side, the iron core being insertable into the shunt coil, and the iron core being disposed away from or close to the shunt coil along with the first side; or, the mating member is an inner coil fixed to the first side, the inner coil being insertable into the shunt coil, and the inner coil being disposed away from or close to the shunt coil along with the first side.

[0025] Another objective of this invention is to provide a circuit breaker that includes the aforementioned shunt trip unit.

[0026] In some embodiments, the shunt trip unit includes a trip unit body and a control box, the shunt coil is disposed in the trip unit body, and the voltage control system is disposed in the control box; the circuit breaker has a housing and a mounting cavity located inside the housing, the trip unit body is located in the mounting cavity, and the control box is disposed outside the housing.

[0027] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art: When performing remote tripping operations, the voltage control system of this utility model first switches to the first mode. In this mode, a closed circuit is formed between the power supply and the shunt coil. The power supply energizes the shunt coil, which generates electromagnetic force, causing the shunt trip unit to perform a tripping operation. As the power supply continues to provide power, the capacitor is fully charged, and the voltage control system switches to the second mode. In this mode, a closed circuit is formed between the power supply, the step-down circuit, and the shunt coil. The step-down circuit reduces the voltage output by the power supply, allowing the shunt coil to be powered by a lower voltage. This prevents the shunt coil from burning out and allows the shunt trip unit to remain in the tripping operation state, avoiding accidental reclosing of the circuit breaker and improving safety performance. Attached Figure Description

[0028] Appendix Figure 1 This is a schematic diagram of a shunt trip unit according to a specific embodiment of the present invention;

[0029] Appendix Figure 2 This is a schematic diagram of the main body of the trip unit according to a specific embodiment;

[0030] Appendix Figure 3 For the appendix Figure 2 Top view;

[0031] Appendix Figure 4 For the attached Figure 3 Schematic sectional view along the middle AA direction;

[0032] Appendix Figure 5 For the appendix Figure 2 A schematic diagram of the middle section structure;

[0033] Appendix Figure 6 This is a schematic diagram of a control box according to a specific embodiment;

[0034] Appendix Figure 7 This is a schematic diagram of a power supply, a power control system, and a shunt coil according to a specific embodiment.

[0035] Appendix Figure 8 This is a schematic diagram of a step-down circuit according to a specific embodiment;

[0036] The components are as follows: 100, shunt trip unit; 110, main body; 120, control box; 1201, first terminal; 1202, second terminal; 1203, third terminal; 1204, fourth terminal; 200, power supply; 300, voltage control system; 310, step-down circuit; 320, MOSFET; 330, operational amplifier; 1, housing; 10, accommodating cavity; 11, coil frame; 2, trip push rod; 21, first side; 22, second side; 23, mating part; 3, micro switch; 4, auxiliary push rod; 41, trigger part; 42, drive part. Detailed Implementation

[0037] The technical solution of this utility model will be described in detail below with reference to the accompanying drawings and specific embodiments, so that the advantages and features of this utility model can be more easily understood by those skilled in the art. Obviously, the embodiments described in this application are only a part of the embodiments, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.

[0038] To address the risk of reclosing most circuit breakers after remote tripping, one approach is to continuously energize the coil to maintain the tripped state of the shunt trip unit and prevent reclosing. However, continuous energizing leads to coil temperature rise. Therefore, the following solution is proposed that maintains energizing for an extended period while preventing excessive coil temperature increase.

[0039] This embodiment provides a circuit breaker including a shunt trip unit 100 connected to a power supply 200. The shunt trip unit 100 is used to remotely trip the circuit breaker, thereby ensuring circuit safety. The shunt trip unit 100 includes a shunt coil L1 and a voltage control system 300. The shunt coil L1 has a first conductive terminal for input current and a second conductive terminal for output current, and the first and second conductive terminals are respectively connected to the power supply 200. See also... Figure 7As shown, the voltage control system 300 includes a step-down circuit 310, a switching module, a MOSFET 320, and a capacitor C1. The input terminal of the step-down circuit 310 is connected to the power supply 200, and the output terminal of the step-down circuit 310 is connected to a first conductive terminal. The voltage at the output terminal of the step-down circuit 310 is lower than the voltage at the input terminal, and it is used to step down the power supply voltage. The switching module includes a drive coil J1 and a switch contact J2 controlled by the drive coil J1. The switch contact J2 is connected between the power supply 200 and the first conductive terminal. The drive coil J1 is connected to the output terminal of the step-down circuit 310. The source S of the MOSFET 320 is connected to the drive coil J1, and the drain D of the MOSFET 320 is connected to the power supply 200. The capacitor C1 is connected to the output terminal of the step-down circuit 310 and also to the gate G of the MOSFET 320.

[0040] The voltage control system 300 has a first mode and a second mode. When the power supply voltage is input, the first mode is activated. In this mode, the MOSFET 320 is turned on, thus forming a first closed circuit between the power supply 200, the step-down circuit 310, and the drive coil J1. The drive coil J1 drives the switch contact J2 to close, thereby forming a second closed circuit between the power supply 200 and the shunt trip coil L1. The shunt trip unit 100 is energized and performs a tripping operation. As the power supply voltage continues to be input, the capacitor C1 is fully charged, and the voltage control system 300 switches to the second mode. In this mode, the MOSFET 320 is turned off, the switch contact J2 is opened, and a third closed circuit is formed between the power supply 200, the step-down circuit 310, and the shunt trip coil L1. In the second mode, although the shunt trip unit 100 is continuously powered, the voltage is first stepped down by the step-down circuit 310, so that the voltage output to the shunt coil L1 is lower and will not burn out the shunt coil L1. Since the shunt trip unit 100 is continuously powered, the shunt trip unit 100 can maintain the state of performing the trip operation.

[0041] In this embodiment, see Figures 1 to 3 As shown, the shunt trip unit 100 includes a trip unit body 110, see [link / reference]. Figure 4 , Figure 5As shown, the trip unit body includes a housing 1 and a trip push rod 2. The housing 1 has an internal cavity 10, in which the shunt coil L1 is disposed. The middle part of the trip push rod 2 is rotatably disposed from the housing 1. The trip push rod 2 has a first side 21 and a second side 22 disposed on opposite sides. The first side 21 is provided with a mating part 23 that cooperates with the shunt coil L1 to drive the first side 21 to rotate under the electromagnetic force of the shunt coil L1. The trip push rod 2 has an initial position and a tripped position. When in the initial position, the second side 22 is retracted relative to the housing 1, and the first side 21 is away from the shunt coil L1. When the shunt coil L1 is energized, the shunt coil L1 drives the mating part 23, thereby causing the trip push rod 2 to rotate and move towards the tripped position. When in the tripped position, the first side 21 is close to the shunt coil L1, and the second side 22 is away from the housing 1. At this time, the second side 22 can trigger the free tripping mechanism inside the circuit breaker, thereby causing the circuit breaker to trip and open. In this embodiment, when the voltage control system 300 switches to the first mode, the power supply 200 energizes the shunt coil L1, and the tripping push rod 2 moves to the tripping position. When the voltage control system 300 is in the second mode, the tripping push rod 2 remains in the tripping position.

[0042] In this embodiment, the trip unit body includes a first elastic element (not shown in the figure), which provides the force required to drive the trip push rod 2 to move to the initial position. The first elastic element helps maintain the trip push rod 2 in the initial position without external force, preventing accidental tripping. Simultaneously, after the shunt coil L1 is de-energized, the trip push rod 2 automatically moves from the tripped position to the initial position under the force of the first elastic element.

[0043] In this embodiment, the mating member 23 is an iron core fixedly disposed on the first side portion 21. The iron core can be inserted into the shunt coil L1, and the iron core can be disposed away from or close to the shunt coil L1 along with the first side portion 21. In some embodiments, the mating member 23 is an inner coil fixedly disposed on the first side portion 21. The inner coil can be inserted into the shunt coil L1, and the inner coil can be disposed away from or close to the shunt coil L1 along with the first side portion 21.

[0044] In this embodiment, see Figure 4 , Figure 5 As shown, the housing 1 has a coil frame 11 inside, and the shunt coil L1 is wound around the outside of the coil frame 11. The coil frame 11 is cylindrical, and the mating part 23 can be inserted into the coil frame 11.

[0045] In this embodiment, the voltage control system 300 includes an operational amplifier 330, which is positioned between the output of the step-down circuit 310 and the capacitor C1. The high potential at the output of the operational amplifier 330 not only allows for rapid charging and discharging of the MOSFET 320, increasing the speed of MOSFET turn-on and turn-off, but also enables the shunt trip unit 100 to quickly perform a tripping operation upon receiving a remote tripping command. Simultaneously, the operational amplifier 330 also rapidly charges the capacitor C1, allowing the voltage control system 300 to quickly switch from the first mode to the second mode, reducing the time the voltage control system 300 remains in the first mode, thereby reducing the time high voltage is applied to the shunt coil L1 and preventing the shunt coil L1 from burning out.

[0046] In this embodiment, the switching module is an electromagnetic relay. In this embodiment, the shunt coil L1 is connected in parallel with a diode to protect the control system circuit. Specifically, the anode of the diode is connected to the second conductive terminal of the shunt coil L1, and the cathode of the diode is connected to the first conductive terminal of the shunt coil L1. In this embodiment, the drive coil J1 is also connected in parallel with a diode to protect the control system circuit. The connection method between the diode and the drive coil J1 is similar to that of the diode and drive coil J1.

[0047] In this embodiment, see Figure 8 As shown, the step-down circuit 310 uses a power supply chip LC, and the input terminal of the power supply chip LC is connected to the power supply 200. In other embodiments, the step-down circuit 310 can be replaced by other circuits capable of performing the step-down function.

[0048] In this embodiment, see Figure 4 , Figure 5As shown, the trip unit body 110 also includes a micro switch 3 and an auxiliary push rod 4, wherein the micro switch 3 is disposed in the receiving cavity 10. The middle part of the auxiliary push rod 4 is rotatably disposed from the housing 1, and the auxiliary push rod 4 has a trigger part 41 and a drive part 42 disposed on opposite sides, with at least a portion of the drive part 42 extending to the outside of the housing 1. The micro switch 3 is located on the movement path of the trigger part 41, specifically, the trigger button of the micro switch 3 is located on the movement path of the trigger part 41. The micro switch 3 is connected to an indicator signal, and the indicator can send different indication information according to different received signals to remind the operator of the status of the circuit breaker, i.e., the open or closed state. When performing the open operation, the auxiliary push rod 4 is driven, specifically, the drive part 42 is driven to rotate, thereby driving the trigger part 41 to rotate. In some embodiments, when no tripping operation is performed, the trigger part 41 is in contact with the trigger button, and the micro switch 3 sends a first signal to the indicator. After the tripping operation is performed, the trigger part 41 moves away from the trigger button, and the indicator receives a second signal. In other embodiments, when no tripping operation is performed, the trigger part 41 moves away from the trigger button. After the tripping operation is performed, the trigger part 41 moves towards the micro switch 3 and contacts the trigger button. Both the tripping push rod 2 and the auxiliary push rod 4 described above operate using the lever principle.

[0049] In this embodiment, the trip unit body 110 also includes a second elastic element (not shown in the figure), which is used to provide the force required to drive the auxiliary push rod 4 to rotate. The second elastic element is also used to maintain the state of the auxiliary push rod 4 and can drive the auxiliary push rod 4 to reset when the external force is removed.

[0050] In this embodiment, the shunt trip unit further includes a control box 120, and the voltage control system 300 is disposed within the control box 120. Specifically, the control box 120 has four terminals, two of which are connected to the power supply 200, and the other two are connected to the first conductive terminal and the second conductive terminal, respectively. See also Figure 6 As shown, the four terminals are the first terminal 1201, the second terminal 1202, the third terminal 1203, and the fourth terminal 1204. The first terminal 1201 and the second terminal 1202 are connected to the power supply 200, and the third terminal 1203 and the fourth terminal 1204 are connected to the first conductive terminal and the second conductive terminal, respectively.

[0051] In this embodiment, only one microswitch is installed inside the trip unit body 110, allowing for compression of the trip unit body 110's volume. This makes it suitable for small-sized circuit breakers or circuit breakers with limited internal space. In this embodiment, the circuit breaker has a housing and a mounting cavity inside the housing. The trip unit body 110 is located in the mounting cavity, and the control box 120 is located outside the housing. This reduces the space occupied inside the circuit breaker, making it well-suited for small-sized circuit breakers or circuit breakers with limited internal space.

[0052] In summary, the circuit breaker of this embodiment has a shunt trip unit 100 that can perform both shunt tripping and auxiliary functions. When performing shunt tripping, the voltage control system 300 first switches to the first mode, triggering the trip push rod 2 to move to the tripping position and achieving remote tripping. Then, the voltage control system 300 can quickly switch to the second mode to prevent the shunt coil L1 from burning out and continuously outputs a low voltage to maintain the shunt coil L1's energization, keeping the trip push rod 2 in the tripped state and preventing the circuit breaker from being accidentally closed. Specifically, the capacitor C1 takes approximately 0.3 seconds to fully charge, meaning the voltage control system 300 can switch from the first mode to the second mode in just 0.3 seconds, and the shunt coil L1 is only supplied with power for 0.3 seconds. The step-down circuit 310 is a 24V step-down circuit; in the second mode, the shunt coil L1 is powered by 24V.

[0053] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A shunt trip unit, connected to a power supply, characterized in that: The shunt trip unit includes a shunt coil and a voltage control system. The shunt coil has a first conductive terminal for input current and a second conductive terminal for output current. The second conductive terminal is connected to the power supply. The voltage control system includes: A step-down circuit, wherein the input terminal of the step-down circuit is connected to the power supply, the output terminal of the step-down circuit is connected to the first conductive terminal, and the voltage at the output terminal of the step-down circuit is lower than the voltage at the input terminal; A switching module includes a drive coil and a switch contact controlled by the drive coil, the switch contact being connected between the power supply and the first conductive terminal, and the drive coil being connected to the output terminal of the step-down circuit; A MOS transistor, wherein the source of the MOS transistor is connected to the driving coil, and the drain of the MOS transistor is connected to the power supply; A capacitor is connected to the output terminal of the step-down circuit and to the gate of the MOS transistor. The voltage control system has a first mode and a second mode. In the first mode, the MOSFET is turned on, a first closed circuit is formed between the power supply, the step-down circuit and the drive coil, the switch contacts are closed, and a second closed circuit is formed between the power supply and the shunt coil. In the second mode, the capacitor is fully charged, the MOSFET is turned off, the switch contacts are open, and a third closed circuit is formed between the power supply, the step-down circuit and the shunt coil.

2. The shunt trip unit according to claim 1, characterized in that: The voltage control system includes an operational amplifier, which is disposed between the output terminal of the buck circuit and the capacitor. And / or, the step-down circuit uses a power supply chip, and the input terminal of the power supply chip is connected to the power supply.

3. The shunt trip unit according to claim 1, characterized in that: The switching module is an electromagnetic relay; and / or, the shunt coil is connected in parallel with a diode; and / or, the drive coil is connected in parallel with a diode.

4. The shunt trip unit according to claim 1, characterized in that: Includes a trip unit body, the trip unit body comprising: A housing, the housing having an internal cavity, and the shunt coil disposed in the internal cavity; A tripping push rod is rotatably disposed in the middle of the housing. The tripping push rod has a first side and a second side located on opposite sides. The first side is provided with a cooperating component that engages with the shunt coil to drive the first side to rotate under the electromagnetic force of the shunt coil. The tripping push rod has an initial position and a tripping position. When in the initial position, the second side is retracted relative to the housing. When in the tripping position, the second side is moved away from the housing. When the control system is in the second mode, the tripping push rod remains in the tripping position.

5. The shunt trip unit according to claim 4, characterized in that: The shunt trip unit also includes a control box, and the voltage control system is disposed in the control box; The control box has four terminals, two of which are connected to the power supply, and the other two are connected to the first conductive terminal and the second conductive terminal, respectively.

6. The shunt trip unit according to claim 4 or 5, characterized in that: The trip unit body includes: A micro switch is disposed in the accommodating cavity; An auxiliary push rod is rotatably disposed in the middle of the housing. The auxiliary push rod has a trigger part and a drive part disposed on opposite sides. At least part of the drive part extends to the outside of the housing. The micro switch is located on the movement path of the trigger part. The second elastic element is used to provide the force required to drive the auxiliary push rod to rotate.

7. The shunt trip unit according to claim 4, characterized in that: The trip unit body includes a first elastic element, which provides the force required to drive the trip push rod to the initial position.

8. The shunt trip unit according to claim 4, characterized in that: The mating component is an iron core fixed to the first side, the iron core being able to be inserted into the shunt excitation coil, and the iron core being able to be positioned away from or close to the shunt excitation coil along with the first side; or, the mating component is an inner coil fixed to the first side, the inner coil being able to be inserted into the shunt excitation coil, and the inner coil being able to be positioned away from or close to the shunt excitation coil along with the first side.

9. A circuit breaker, characterized in that: Includes the shunt trip unit as described in any one of claims 1 to 8.

10. The circuit breaker according to claim 9, characterized in that: The shunt trip unit includes a trip unit body and a control box. The shunt coil is disposed in the trip unit body, and the voltage control system is disposed in the control box. The circuit breaker has a housing and a mounting cavity located inside the housing. The trip unit body is located in the mounting cavity, and the control box is disposed outside the housing.

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