A ring main unit

Abstract

The invention discloses a ring network cabinet, comprising: a master reclosing circuit breaker and each slave reclosing circuit breaker are connected to different power lines, the master reclosing circuit breaker is connected to an external control terminal through a dry contact circuit, and is connected to each slave reclosing circuit breaker; when the master reclosing circuit breaker or at least one slave reclosing circuit breaker fails, the master reclosing circuit breaker controls the dry contact circuit to be turned on, and sends an alarm signal to the external control terminal, and the external control terminal sends an alarm signal to notify maintenance personnel to perform maintenance, thereby realizing online monitoring of the operating status of the ring network cabinet and reducing maintenance costs.

Description

Technical Field

[0001] The invention relates to the field of electric power technology, and in particular to a ring network cabinet. Background Art

[0002] The ring main unit is an electrical device in which a group of high-voltage switchgear is installed in a steel plate metal cabinet or made into an assembled interval ring main unit. Its core part adopts load switches and fuses, which have the advantages of simple structure, small size, low price, and can improve power supply parameters and performance as well as power supply safety. A power fault protection device must be installed in the ring main unit to effectively prevent personal electric shock and fire accidents. Circuit breakers are indispensable electronic components of circuit fault protection devices and are widely used in various fields of electronic circuits. Since the circuit fault protection device itself may also fail, such as when the service life of the internal components ends or the circuit breaker is out of service, the circuit fault protection function is lost. In this case, if the device continues to be used, personal electric shock or fire accidents may occur. For this reason, it is necessary to detect whether the circuit breaker in the ring main unit is faulty in real time, but the existing detection circuit requires manual detection signals and cannot automatically diagnose, so it cannot reflect the current operating status of the circuit breaker in time. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the self-test circuit of the circuit breaker in the ring main unit cannot timely reflect its current operating status, thereby providing a ring main unit.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] An embodiment of the present invention provides a ring network cabinet, including: a dry contact circuit, a master reclosing circuit breaker and a plurality of slave reclosing circuit breakers, wherein the master reclosing circuit breaker and each slave reclosing circuit breaker are connected to different power lines, the master reclosing circuit breaker is connected to an external control terminal through a dry contact circuit, and is connected to each slave reclosing circuit breaker; when the master reclosing circuit breaker fails or loses power, or at least one slave reclosing circuit breaker fails or loses power, the master reclosing circuit breaker controls the dry contact circuit to be turned on, sends an alarm signal to the external control terminal, and the external control terminal sends an alarm signal.

[0006] In one embodiment, the dry contact circuit includes: a control circuit and a relay circuit, wherein the control circuit is respectively connected to the main control reclosing circuit breaker and the relay circuit, and is used to control the conduction of the relay circuit according to the received control signal; the relay circuit is connected to the external control terminal, and is used to cause the external control terminal to send an alarm signal when the relay circuit is in conduction.

[0007] In one embodiment, the control circuit includes: a first diode, a second diode, a first resistor, a second resistor, a third resistor, a first switch tube and a second switch tube, wherein the cathodes of the first diode and the second diode are connected to the control end of the first switch tube through the first resistor, and the first resistor is connected to the ground end through the second resistor; the anodes of the first diode and the second diode are connected to the main control reclosing circuit breaker; the first end of the first switch tube is connected to the control end of the second switch tube, and is connected to an external power supply through the third resistor, and its second end is connected to the ground end; the first end of the second switch tube is connected to the relay circuit, and its second end is connected to the ground end.

[0008] In one embodiment, the relay circuit includes: a fourth resistor and a relay, wherein a first end of the relay is connected to an external power supply through the fourth resistor, a second end of the relay is connected to a first end of a second switch tube, and a third end and a fourth end of the relay are both connected to an external control terminal.

[0009] In one embodiment, each reclosing circuit breaker is connected to a communication module, each communication module is used to realize data transmission between the master reclosing circuit breaker and each slave reclosing circuit breaker, and the communication module adopts Bluetooth communication.

[0010] In one embodiment, the master-controlled reclosing circuit breaker includes: a polling module, which is used to obtain its own on-off state, and obtain the on-off state of all slave-controlled reclosing circuit breakers by polling at a first preset time interval, and judge whether it is in an open state or at least one slave-controlled reclosing circuit breaker is in an open state. When it is in an open state or at least one slave-controlled reclosing circuit breaker is in an open state, the alarm signal is sent to an external control terminal by controlling the dry contact circuit to be turned on, and the external control terminal sends an alarm signal.

[0011] In one embodiment, the polling module is also used to obtain the on-off status of all slave-controlled reclosing circuit breakers by polling at a first preset time interval, and determine whether the on-off status of all slave-controlled reclosing circuit breakers is successfully obtained. When the on-off status of at least one slave-controlled reclosing circuit breaker is not successfully obtained, it is determined that the communication module of the slave-controlled reclosing circuit breaker is faulty, and the dry contact circuit is controlled to be turned on, and an alarm signal is sent to an external control terminal, and the external control terminal sends an alarm signal.

[0012] In one embodiment, each reclosing circuit breaker housing is set with its own Mac address and its corresponding QR code, and the operation and maintenance personnel establish a communication connection between the master reclosing circuit breaker and the slave reclosing circuit breaker by scanning the QR code through the control terminal.

[0013] In one embodiment, a toggle switch is provided on each reclosing circuit breaker, and the operation and maintenance personnel lock or unlock the automatic reclosing function of the reclosing circuit breaker by controlling the state of the toggle switch.

[0014] In one embodiment, the reclosing circuit breaker includes: a control module, which is used to open the reclosing circuit breaker when a fault occurs in the power line, and close it after a second preset time. When the reclosing circuit breaker is opened again after judging that it is in a closed state, it will self-lock and will not close again; record the number of times the reclosing circuit breaker is closed within a third preset time, and judge whether the recorded number of reclosing times within the third preset time exceeds the preset number of reclosing times. If it exceeds, it will self-lock and will not close again. If it does not exceed, the control module clears the recorded number of reclosing times.

[0015] The technical solution of the present invention has the following advantages:

[0016] 1. In the ring main unit provided by the present invention, the master reclosing circuit breaker is connected to the control terminal through a dry contact circuit. The master reclosing circuit breaker adopts a polling method to query the status of each slave reclosing circuit breaker at a first preset time interval. When the master reclosing circuit breaker fails or at least one slave reclosing circuit breaker fails, the master reclosing circuit breaker will send an alarm signal to the external control terminal through the dry contact circuit. The external control terminal sends an alarm signal to notify the maintenance personnel to perform maintenance, thereby realizing online monitoring of the operating status of the ring main unit and reducing maintenance costs.

[0017] 2. The ring main unit provided by the present invention is provided with a toggle switch to lock and unlock the reclosing function of the reclosing circuit breaker, thereby solving the problem of needing to manually close the circuit breaker after the circuit breaker in the ring main unit trips due to an occasional fault, thereby saving manpower and material resources; the built-in control module of each reclosing circuit breaker performs fault diagnosis on the reclosing circuit breaker, and when a fault occurs, the self-locking mechanism is activated to prevent damage to the power line due to the circuit breaker fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A composition diagram of a specific example of a ring main unit provided in an embodiment of the present invention;

[0020] Figure 2A composition diagram of another specific example of a ring main unit provided by an embodiment of the present invention;

[0021] Figure 3 The specific circuit structure of the dry contact circuit provided by the embodiment of the present invention;

[0022] Figure 4 A composition diagram of another specific example of a ring main unit provided by an embodiment of the present invention;

[0023] Figure 5 A composition diagram of another specific example of a ring main unit provided by an embodiment of the present invention;

[0024] Figure 6 A composition diagram of another specific example of a ring main unit provided by an embodiment of the present invention;

[0025] Figure 7 A composition diagram of another specific example of a ring main unit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example

[0031] The embodiment of the present invention provides a ring main unit, which is applied to the occasions where the reclosing circuit breaker in the ring main unit needs to be monitored in real time. Figure 1 It is a reclosing circuit breaker solution based on the ring main unit application scenario, that is, the embodiment of the present invention only performs fault detection on the ring main unit with the reclosing circuit breaker installed. Therefore, the ring main unit of the embodiment of the present invention not only includes: a dry contact circuit 1, a master-controlled reclosing circuit breaker 2 and multiple slave-controlled reclosing circuit breakers 3, but also includes other equipment, which will not be repeated here.

[0032] The master reclosing circuit breaker 2 and each slave reclosing circuit breaker 3 of the embodiment of the present invention are connected to different power lines, such as Figure 1 As shown, the master reclosing circuit breaker 2 is connected to an external control terminal through a dry contact circuit 1 and is connected to each slave reclosing circuit breaker 3 .

[0033] In the power system, a ring network refers to a ring distribution network, that is, the power supply trunk line forms a closed ring, the power supply source supplies power to the ring trunk line, and then distributes power to the outside through high-voltage switches one by one from the trunk line. In order to monitor whether the power line fails in real time and meet the needs of easy maintenance, the embodiment of the present invention arranges multiple reclosing circuit breakers in the ring network cabinet, and selects a master reclosing circuit breaker 2 from the many reclosing circuit breakers, and the unselected reclosing circuit breakers are slave reclosing circuit breakers 3. Each slave reclosing circuit breaker 3 is connected to the master reclosing circuit breaker 2, and the master reclosing circuit breaker 2 is connected to an external control terminal through a dry contact circuit 1.

[0034] In an embodiment of the present invention, the master reclosing circuit breaker 2 polls the operating status (open state or closed state) of each slave reclosing circuit breaker 3 in sequence (in an open state or a closed state) at a first preset time interval. When the master reclosing circuit breaker 2 or at least one slave reclosing circuit breaker 3 fails (the master reclosing circuit breaker 2 is in an open state or at least one slave reclosing circuit breaker 3 is in an open state), the master reclosing circuit breaker 2 controls the dry contact circuit 1 to be turned on, and sends an alarm signal to an external control terminal, and the external control terminal sends an alarm signal.

[0035] In addition, in the embodiment of the present invention, when the master reclosing circuit breaker or at least one slave reclosing circuit breaker is powered off, the dry contact circuit 1 is turned on, and the external control terminal also sends out an alarm signal.

[0036] The control terminal of the embodiment of the present invention can be composed of an intelligent terminal with a built-in alarm module. When the intelligent terminal is connected to the main control reclosing circuit breaker, the alarm module alarms, and the intelligent terminal can be connected to the communication terminal. The communication terminal can enable the operation and maintenance personnel to perform operation and maintenance management of the ring network cabinet through a mobile phone APP or the like.

[0037] In the ring main unit provided by the embodiment of the present invention, the master reclosing circuit breaker is connected to the control terminal through a dry contact circuit. The master reclosing circuit breaker adopts a polling method to query the status of each slave reclosing circuit breaker at a first preset time interval. When the master reclosing circuit breaker fails or at least one slave reclosing circuit breaker fails, the master reclosing circuit breaker will send an alarm signal to the external control terminal through the dry contact circuit. The external control terminal sends an alarm signal to notify the maintenance personnel to perform maintenance, thereby realizing online monitoring of the operating status of the ring main unit and reducing maintenance costs.

[0038] In a specific embodiment, if Figure 2 As shown, the dry contact circuit 1 includes: a control circuit 11 and a relay circuit 12 .

[0039] like Figure 2 As shown, the control circuit 11 of the embodiment of the present invention is respectively connected to the main control reclosing circuit breaker and the relay circuit 12, and is used to control the conduction of the relay circuit 12 according to the received control signal; the relay circuit 12 is connected to the external control terminal, and is used for the external control terminal to send an alarm signal when it is turned on.

[0040] When the master reclosing circuit breaker 2 and the slave reclosing circuit breaker 3 are not in the open state (or the master reclosing circuit breaker 2 and the slave reclosing circuit breaker 3 are not powered off), the control circuit 11 drives the relay circuit 12 to make the dry contact circuit 1 in the off state (that is, the relay circuit is in the off state). When the master reclosing circuit breaker 2 or at least one slave reclosing circuit breaker 3 is in the open state, the master reclosing circuit breaker 2 outputs a control signal to the control circuit 11 to control the relay circuit 12 to turn on. After that, the master reclosing circuit breaker 2 is connected to the external control terminal, and the external control terminal sends an alarm signal.

[0041] In a specific embodiment, if Figure 3 The control circuit 11 shown includes: a first diode D5, a second diode D6, a first resistor R12, a second resistor R13, a third resistor R11, a first switch tube Q2 and a second switch tube Q1.

[0042] like Figure 3As shown, the cathodes of the first diode D5 and the second diode D6 are connected to the control end of the first switch tube Q2 through the first resistor R12, and the first resistor R12 is connected to the ground end through the second resistor R13; the anodes of the first diode D5 and the second diode D6 are connected to the main control reclosing circuit breaker 2; the first end of the first switch tube Q2 is connected to the control end of the second switch tube Q1, and is connected to the external power supply through the third resistor R11, and its second end is connected to the ground end; the first end of the second switch tube Q1 is connected to the relay circuit 12, and its second end is connected to the ground end.

[0043] When the master reclosing circuit breaker 2 is in the open state, the master reclosing circuit breaker 2 passes Figure 3 The MCU-6 terminal sends a control signal to the control circuit 11. At this time, the first switch tube Q2 is turned on, the second switch tube Q1 is turned off, the relay circuit loses power, and the dry contact circuit is turned on; when at least one slave-controlled reclosing circuit breaker 3 is in an open or power-off state, the master-controlled reclosing circuit breaker 2 is turned on by Figure 3 The BLE-6 terminal sends a control signal to the control circuit 11. At this time, the first switch tube Q2 is turned on, the second switch tube Q1 is turned off, the relay circuit loses power, and the dry contact circuit is turned on.

[0044] When the main control reclosing circuit breaker 2 is in the circuit-breaking state, that is, the branch where the circuit breaker is located loses power, the switch tubes Q2 and Q1 are both turned off, the relay circuit loses power, and the dry contact circuit is turned on.

[0045] In a specific embodiment, if Figure 3 The relay circuit 12 shown includes: a fourth resistor R1 and a relay U2.

[0046] like Figure 3 As shown, the first end of the relay U2 is connected to the external power supply through the fourth resistor R1, the second end is connected to the first end of the second switch tube Q1, and the third end and the fourth end are both connected to the external control terminal.

[0047] The connection terminal P4 of the relay circuit 12 of the embodiment of the present invention is connected to the external control terminal. When the second switch tube Q1 in the control circuit 11 is turned off, the relay U2 loses power, the dry contact circuit is turned on, the main control reclosing circuit breaker 2 is connected to the external control terminal, and the external control terminal sends an alarm signal.

[0048] In a specific embodiment, if Figure 4As shown, in the embodiment of the present invention, the master reclosing circuit breaker 2 and all the slave reclosing circuit breakers 3 are connected to the corresponding communication module 4, and this communication module 4 can use Bluetooth communication. The master reclosing circuit breaker 2 communicates with other slave reclosing circuit breakers 3 through the communication module 4 connected to it and the communication modules 4 connected to other slave reclosing circuit breakers 3, and adopts a polling method to query each slave reclosing circuit breaker 3 in turn at a first preset time interval to see whether it is in an open state. When the master reclosing circuit breaker 2 or at least one slave reclosing circuit breaker 3 is in an open state, a control signal is sent to the dry contact circuit 1.

[0049] In a specific embodiment, if Figure 5 As shown, the master-controlled reclosing circuit breaker 2 includes: a polling module 21, which is used to obtain its own on-off state, and obtain the on-off state of all slave-controlled reclosing circuit breakers 3 by polling at a first preset time interval, and judge whether it is in an open state or at least one slave-controlled reclosing circuit breaker 3 is in an open state. When it is in an open state or at least one slave-controlled reclosing circuit breaker 3 is in an open state, the dry contact circuit 1 is controlled to be turned on, and an alarm signal is sent to an external control terminal, and the external control terminal sends an alarm signal.

[0050] The polling module 21 of the master reclosing circuit breaker 2 of the embodiment of the present invention sequentially and cyclically queries whether other slave reclosing circuit breakers 3 are in the open state at a first preset time interval. When they are in the open state, the dry contact circuit 1 is controlled to be turned on, and an alarm signal is sent to the external control terminal, and the external control terminal sends an alarm signal. In addition, when the master reclosing circuit breaker 2 is in the open state, the external control terminal also sends an alarm signal.

[0051] The polling module 21 of the embodiment of the present invention is also used to obtain the on-off status of all slave-controlled reclosing circuit breakers 3 by polling at a first preset time interval, and determine whether the on-off status of all slave-controlled reclosing circuit breakers 3 is successfully obtained. When the on-off status of at least one slave-controlled reclosing circuit breaker 3 is not successfully obtained, it is determined that the communication module 4 of the slave-controlled reclosing circuit breaker 3 is faulty, and the dry contact circuit 1 is controlled to be turned on, and an alarm signal is sent to an external control terminal, and the external control terminal sends an alarm signal.

[0052] In an embodiment of the present invention, when the master reclosing circuit breaker 2 communicates with other slave reclosing circuit breakers 3 through the communication module 4, when the polling module 21 queries the on / off state of the slave reclosing circuit breaker 3, if the polling module 21 fails to successfully obtain the on / off state of the slave reclosing circuit breaker 3, then the dry contact circuit 1 is controlled to be turned on, and an alarm signal is sent to the external control terminal, and the external control terminal sends an alarm signal.

[0053] In a specific embodiment, if Figure 6 As shown, the reclosing circuit breaker includes: a control module 22, which is used to open the reclosing circuit breaker when a fault occurs in the power line, and close it after a second preset time. When the reclosing circuit breaker is opened again after judging that it is in a closed state, it will self-lock and will not close again; record the number of times the reclosing circuit breaker is closed within a third preset time, and judge whether the recorded number of reclosing times within the third preset time exceeds the preset number of reclosing times. When it exceeds, it will self-lock and will not close again. When it does not exceed, the control module 22 clears the recorded number of reclosing times.

[0054] A control module 22 is provided in each reclosing circuit breaker (including the master reclosing circuit breaker 2 and the slave reclosing circuit breaker 3) in the embodiment of the present invention. Since the circuit breakers in the embodiment of the present invention are all reclosing circuit breakers, when the power line to which they are connected fails, the reclosing circuit breaker is opened and closed after a second preset time. If the reclosing circuit breaker is opened again after being closed, the control module 22 of the reclosing circuit breaker is self-locked and no longer closed.

[0055] In addition, the control module 22 is also used to record the number of times the reclosing circuit breaker is closed within a third preset time. When the number of reclosing times recorded by the control module 22 exceeds the preset number of reclosing times within the third preset time, it will self-lock and no longer close. When it does not exceed the preset number of reclosing times, the control module 22 clears the recorded number of reclosing times.

[0056] It should be noted that the control methods, query methods, judgment methods, etc. involved in the control module 22 and the polling module 21 are all mature control methods, query methods, and judgment methods in the prior art, and will not be repeated here.

[0057] In a specific embodiment, the embodiment of the present invention prints each Mac address and its corresponding QR code on the outer casing of each reclosing circuit breaker. When the master reclosing circuit breaker 2 has not established a communication connection with other slave reclosing circuit breakers 3, the operation and maintenance personnel establish a communication connection between the master reclosing circuit breaker 2 and the slave reclosing circuit breaker 3 by scanning the QR code through the control terminal.

[0058] In a specific embodiment, if Figure 7 As shown, each reclosing circuit breaker is provided with a toggle switch 5, and the operation and maintenance personnel lock or unlock the automatic reclosing function of the reclosing circuit breaker by controlling the state of the toggle switch 5.

[0059] In the embodiment of the present invention, a toggle switch 5 is provided in each reclosing circuit breaker, and the wave switch controls whether the reclosing circuit breaker has a reclosing function. When the toggle switch 5 is turned to the reclosing state, the reclosing circuit breaker has the reclosing function; if the toggle switch 5 is turned to the non-reclosing state, the reclosing circuit breaker turns off the reclosing function. If the reclosing circuit breaker is self-locked by the control module 22 inside it, the toggle switch 5 can be turned from the non-reclosing state to the reclosing state, and the reclosing circuit breaker is unlocked and has the reclosing function.

[0060] The ring network cabinet provided by the present invention has a master reclosing circuit breaker connected to a control terminal via a dry contact circuit. The master reclosing circuit breaker uses a polling method to query the status of each slave reclosing circuit breaker at a first preset time interval. When the master reclosing circuit breaker fails or at least one slave reclosing circuit breaker fails, the master reclosing circuit breaker sends an alarm signal to an external control terminal via a dry contact circuit. The external control terminal sends an alarm signal to notify maintenance personnel to perform maintenance, thereby realizing online monitoring of the operating status of the ring network cabinet and reducing maintenance costs; a toggle switch is set to lock and unlock the reclosing function of the reclosing circuit breaker, thereby solving the problem of manual closing after the circuit breaker in the ring network cabinet trips due to an occasional fault, which can save manpower and material resources; the built-in control module of each reclosing circuit breaker performs fault diagnosis on the reclosing circuit breaker, and when it fails, the self-locking mechanism is activated to prevent the power line from being damaged due to the circuit breaker failure.

[0061] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A ring main unit, characterized in that: include: Dry contact circuit, master reclosing circuit breaker and multiple slave reclosing circuit breakers, wherein: The master reclosing circuit breaker and each slave reclosing circuit breaker are connected to different power lines, the master reclosing circuit breaker is connected to an external control terminal through a dry contact circuit, and is connected to each slave reclosing circuit breaker; When the master reclosing circuit breaker fails or loses power, or at least one slave reclosing circuit breaker fails or loses power, the master reclosing circuit breaker controls the dry contact circuit to be turned on, sends an alarm signal to the external control terminal, and the external control terminal sends an alarm signal; The master reclosing circuit breaker comprises: a polling module, which is used to obtain its own on-off state, obtain the on-off state of all slave reclosing circuit breakers by polling at a first preset time interval, and judge whether it is in an open state or whether at least one slave reclosing circuit breaker is in an open state. When it is in an open state or at least one slave reclosing circuit breaker is in an open state, an alarm signal is sent to an external control terminal by controlling the dry contact circuit to be turned on, and the external control terminal sends an alarm signal; The polling module is also used to obtain the on-off status of all slave-controlled reclosing circuit breakers by polling at a first preset time interval, and determine whether the on-off status of all slave-controlled reclosing circuit breakers is successfully obtained. When the on-off status of at least one slave-controlled reclosing circuit breaker is not successfully obtained, it is determined that the communication module of the slave-controlled reclosing circuit breaker is faulty, and the alarm signal is sent to the external control terminal by controlling the dry contact circuit to be turned on, and the external control terminal sends an alarm signal.

2. The ring main unit according to claim 1, characterized in that: The dry contact circuit includes: a control circuit and a relay circuit, wherein: A control circuit, which is connected to the main control reclosing circuit breaker and the relay circuit respectively, and is used to control the relay circuit to be turned on according to the received control signal; The relay circuit is connected to an external control terminal and is used for causing the external control terminal to send out an alarm signal when the relay circuit is turned on.

3. The ring main unit according to claim 2, characterized in that: The control circuit includes: a first diode, a second diode, a first resistor, a second resistor, a third resistor, a first switch tube and a second switch tube, wherein: The cathodes of the first diode and the second diode are connected to the control end of the first switch tube through the first resistor, and the first resistor is connected to the ground end through the second resistor; the anodes of the first diode and the second diode are connected to the main control reclosing circuit breaker; A first end of the first switch tube is connected to the control end of the second switch tube, and is connected to an external power supply through a third resistor, and a second end thereof is connected to the ground end; A first end of the second switch tube is connected to the relay circuit, and a second end of the second switch tube is connected to the ground end.

4. The ring main unit according to claim 3, characterized in that: The relay circuit comprises: a fourth resistor and a relay, wherein: The first end of the relay is connected to the external power supply through the fourth resistor, the second end of the relay is connected to the first end of the second switch tube, and the third end and the fourth end of the relay are both connected to the external control terminal.

5. The ring main unit according to claim 4, characterized in that: Each reclosing circuit breaker is connected to a communication module, each of the communication modules is used to realize data transmission between the master reclosing circuit breaker and each slave reclosing circuit breaker, and the communication module adopts Bluetooth communication.

6. The ring main unit according to claim 5, characterized in that: Each reclosing circuit breaker housing is set with its own Mac address and its corresponding QR code. The operation and maintenance personnel establish a communication connection between the master reclosing circuit breaker and the slave reclosing circuit breaker by scanning the QR code through the control terminal.

7. The ring main unit according to claim 4, characterized in that: A toggle switch is provided on each reclosing circuit breaker, and the operation and maintenance personnel lock or unlock the automatic reclosing function of the reclosing circuit breaker by controlling the state of the toggle switch.

8. The ring main unit according to claim 4, characterized in that: The reclosing circuit breaker comprises: The control module is used for, when a fault occurs in a power line, the reclosing circuit breaker is opened, and is closed after a second preset time. When the reclosing circuit breaker is opened again after judging that it is in a closed state, it is locked automatically and no longer closed; the number of times the reclosing circuit breaker is closed within a third preset time is recorded, and it is judged whether the recorded number of reclosing times within the third preset time exceeds the preset number of reclosing times. If it exceeds, it is locked automatically and no longer closed. If it does not exceed, the control module clears the recorded number of reclosing times.

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