A protection system

Abstract

The utility model discloses a protection system relates to the field of circuit, be provided with current collection device, switch module and converter vanadium extraction equipment in protection system, when considering when frequency converter appears the failure, the current of the loop of frequency converter will abnormally increase, therefore the current value of frequency converter output end that controller gathers through current collection device judges whether frequency converter appears the failure to the current value is greater than the preset current threshold value when judging frequency converter appears the failure, the switch module is opened to the controller control at this moment, and then the power supply loop of brake motor is opened, and the converter tilting equipment is stopped in time control rotation, and the emergence of the situation that molten steel is splashed is avoided.

Description

Technical Field

[0001] This utility model relates to the field of circuits, and in particular to a protection system. Background Technology

[0002] Among the many processes for extracting vanadium from molten iron, one of the more important processes is the converter vanadium extraction process. The general process of the converter vanadium extraction process is to first oxidize the vanadium in the vanadium-containing molten iron into vanadium slag and separate it out in a converter before steelmaking.

[0003] Currently, the vanadium extraction equipment in converters using the converter process includes a tilting motor, a frequency converter, a tilting brake, and a converter tilting device. The frequency converter provides power and drives the tilting motor, enabling stable switching between high-speed and low-speed rotation of the converter tilting device. The function of the converter tilting device is to load the molten iron required for one smelting cycle from the start of molten iron charging to the end of smelting, and to rotate according to process requirements at different stages of the smelting cycle. The tilting brake includes a brake contactor, a brake motor, and an electro-hydraulic actuator. The brake contactor closes or closes based on the controller's control. When the brake contactor is closed, the brake motor is energized and drives the electro-hydraulic actuator, maintaining the current state of the converter tilting device. Conversely, if the brake contactor is closed, the converter tilting device stops rotating. Because frequency converters are prone to malfunctions during actual operation due to prolonged working time, they may fail to provide torque output, thus failing to drive the tilting motor. If the brake contactor is closed at this time, meaning the tilting brake is in the open state, the molten steel inside the converter tilting device will spill out due to inertia. Utility Model Content

[0004] The purpose of this utility model is to provide a protection system. Considering that when the frequency converter malfunctions, the current in the circuit where the frequency converter is located will increase abnormally, the controller in this solution uses the current value of the output terminal of the frequency converter collected by the current acquisition device to determine whether the frequency converter has malfunctioned. When the current value is greater than the preset current threshold, the switch module is controlled to disconnect. That is, when the frequency converter malfunctions, the brake motor is de-energized in time, and the converter tilting equipment is stopped from rotating in time, thus avoiding the occurrence of molten steel spillage.

[0005] To solve the above-mentioned technical problems, this utility model provides a protection system, including: a current acquisition device, a switch module, and a converter vanadium extraction device. The converter vanadium extraction device includes: a frequency converter, a tilting motor, a converter vanadium extraction device, and a tilting brake. The tilting brake includes: a brake contactor, a brake motor, and an electro-hydraulic actuator.

[0006] A current acquisition device, wherein the acquisition end of the current acquisition device is connected to the output end of the frequency converter, and the output end is connected to the controller, for acquiring the current value of the output end of the frequency converter;

[0007] The output end of the frequency converter is connected to the converter tilting device via the tilting motor;

[0008] The first end of the main contact of the brake contactor is connected to the electro-hydraulic actuator through the brake motor, and the first end of the coil of the brake contactor is connected to the controller, and the second end is connected to the neutral wire;

[0009] The first end of the switch module is connected to an AC power source, the second end is connected to the second end of the main contact of the brake contactor, and the control end is connected to the controller, which is used to disconnect the switch based on the controller's control when the current value is greater than a preset current threshold.

[0010] Optionally, the switching module includes: a first switch and an intermediate relay;

[0011] The first terminal of the first switch is connected to the AC power supply, the second terminal is connected to the first terminal of the coil of the intermediate relay, and the control terminal is connected to the controller, for closing the switch based on the controller when the current value is greater than a preset current threshold.

[0012] The second end of the coil of the intermediate relay is connected to the neutral wire, the first end of the contact of the intermediate relay is connected to the AC power supply, and the second end of the contact of the intermediate relay is connected to the second end of the main contact of the brake contactor, for disconnection when the first switch is closed.

[0013] Optionally, the switching module includes: a circuit breaker with a trip unit and a second switch;

[0014] The first terminal of the second switch is connected to the AC power supply, the second terminal is connected to the first terminal of the circuit breaker coil, and the control terminal is connected to the controller, for closing the switch based on the controller's control when the current value is greater than a preset current threshold.

[0015] The first end of the circuit breaker's trip unit is connected to the AC power supply, the second end of the circuit breaker's trip unit is connected to the second end of the main contact of the brake contactor, and the second end of the circuit breaker's coil is connected to the neutral wire for disconnection when the second switch is closed.

[0016] Optional, also includes:

[0017] The protection device has a first end connected to the AC power supply and a second end connected to the first end of the second switch, and is used to disconnect when an overvoltage and / or overcurrent occurs in the circuit where the coil of the circuit breaker is located.

[0018] Optional, also includes:

[0019] A thermal relay, wherein the heating element of the thermal relay is connected to the stator of the brake motor, and the normally closed contacts are connected to the first end of the main contacts of the brake contactor and the brake motor respectively, and is used to disconnect when the temperature of the stator of the brake motor is greater than a first preset temperature threshold.

[0020] Optionally, the first end of the auxiliary contact of the brake contactor is connected to a DC power supply, and the second end of the auxiliary contact of the brake contactor is connected to the low potential point of the controller, so that the switching module disconnects based on the control of the controller when the coil of the brake is de-energized and the auxiliary contact of the brake is closed.

[0021] Optional, also includes:

[0022] An adhesion detection device is installed within a preset range from the tilting brake contactor. The output of the adhesion detection device is connected to the controller and is used to detect whether the brake contactor is sticking, so that the switch module can disconnect under the control of the controller when the brake contactor is sticking.

[0023] Optionally, the adhesion detection device includes:

[0024] A vision sensor is installed within a preset range from the brake contactor. The output of the vision sensor is connected to the controller to acquire a preset visual image of the arc-extinguishing cover of the brake contactor, so that the switch module disconnects based on the control of the controller when the vision sensor acquires the preset visual image.

[0025] Optionally, the adhesion detection device includes:

[0026] A temperature detection device is installed within a preset range from the brake contactor. The output of the temperature detection device is connected to the controller to collect the current temperature of the brake contactor, so that the switch module disconnects based on the control of the controller when the current temperature is greater than a second preset temperature threshold.

[0027] Optionally, the adhesion detection device includes:

[0028] A sound sensor is installed within a preset range from the brake contactor. The output of the sound sensor is connected to the controller and is used to collect electromagnetic noise at the brake contactor so that the switch module disconnects based on the control of the controller when the sound sensor collects the electromagnetic noise.

[0029] The purpose of this invention is to provide a protection system. The protection system includes a current acquisition device, a switching module, and a converter vanadium extraction device. Considering that when the frequency converter malfunctions, the current in the circuit where the frequency converter is located will increase abnormally, the controller in this solution determines whether the frequency converter is malfunctioning by acquiring the current value at the output terminal of the frequency converter through the current acquisition device. When the current value is greater than a preset current threshold, the controller determines that the frequency converter is malfunctioning. At this time, the controller controls the switching module to disconnect, thereby disconnecting the power supply circuit of the brake motor, and promptly controlling the converter tilting device to stop rotating, thus preventing the molten steel from spilling. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 A schematic diagram of the structure of a protection system provided by this utility model;

[0032] Figure 2 A schematic diagram of another protection system provided by this utility model. Detailed Implementation

[0033] The core of this utility model is to provide a protection system. Considering that when the frequency converter fails, the current in the circuit where the frequency converter is located will increase abnormally, the controller in this solution judges whether the frequency converter has failed by collecting the current value at the output terminal of the frequency converter through the current acquisition device, and controls the switch module to disconnect when the current value is greater than the preset current threshold. That is, when the frequency converter fails, the brake motor is de-energized in time, and the converter tilting equipment is stopped from rotating in time, thus avoiding the occurrence of molten steel spillage.

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0035] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a protection system provided by the present invention. The protection system includes: a current acquisition device 1, a switch module 2, and a converter vanadium extraction device 3. The converter vanadium extraction device 3 includes: a frequency converter, a tilting motor, and a tilting brake. The tilting brake includes: a brake contactor, a brake motor, and an electro-hydraulic actuator.

[0036] The current acquisition device 1 has its acquisition end connected to the output end of the frequency converter and its output end connected to the controller. It is used to acquire the current value at the output end of the frequency converter.

[0037] The output of the frequency converter is connected to the converter tilting device via a tilting motor;

[0038] The first end of the main contact of the brake contactor is connected to the electro-hydraulic actuator through the brake motor; the first end of the coil of the brake contactor is connected to the controller; and the second end is connected to the neutral wire.

[0039] The first end of the switch module 2 is connected to the AC power supply, the second end is connected to the second end of the main contact of the brake contactor, and the control end is connected to the controller, which is used to disconnect the switch based on the controller when the current value is greater than the preset current threshold.

[0040] In this invention, considering that in the prior art the brake contactor is closed or closed based on the control of the controller, when the brake contactor is closed, the brake motor is energized and drives the electro-hydraulic actuator, at which time the converter tilting device maintains its current state; conversely, if the brake contactor is closed, the converter tilting device stops rotating. In actual operation, frequency converters are prone to failure due to prolonged working time, resulting in the inability to provide torque output and thus the inability to drive the tilting motor. If the brake contactor closes at this time, meaning the tilting brake is in the open state, the molten steel inside the converter tilting device will spill out due to inertia. Therefore, this application aims to first determine the fault condition of the frequency converter and disconnect the power supply circuit of the brake motor after determining that the frequency converter has failed, so that the converter tilting device can stop in time and prevent the molten steel inside the converter from spilling out. In this solution, it is considered that when the frequency converter fails, the current in the circuit where the frequency converter is located will increase abnormally. Therefore, in this solution, the controller determines whether the frequency converter has failed by collecting the current value at the output terminal of the frequency converter through the current acquisition device 1. When the current value is greater than the preset current threshold, the control switch module 2 is disconnected. That is, when the frequency converter fails, the brake motor is de-energized in time, and the converter tilting device is stopped from rotating in time, avoiding the spillage of molten steel.

[0041] It should be noted that in practical applications, the controller can be a PLC cabinet and use PLC logic control. When an abnormality is detected, the PLC cabinet outputs an electrical signal to control the switch module 2 to disconnect, cut off the power supply circuit of the brake motor, and issue a tilting stop command to avoid accidents.

[0042] This embodiment provides a protection system, which includes a current acquisition device 1, a switch module 2, and a converter vanadium extraction device 3. Considering that when the frequency converter malfunctions, the current in the circuit where the frequency converter is located will increase abnormally, the controller in this solution determines whether the frequency converter is malfunctioning by acquiring the current value at the output terminal of the frequency converter through the current acquisition device 1. When the current value is greater than a preset current threshold, the controller determines that the frequency converter is malfunctioning. At this time, the controller controls the switch module 2 to disconnect, thereby disconnecting the power supply circuit of the brake motor, and timely controlling the converter tilting device to stop rotating, thus avoiding the occurrence of molten steel spillage.

[0043] Please refer to Figure 2 , Figure 2 This is a schematic diagram of another protection system provided by the present invention, based on the above embodiments:

[0044] As an optional embodiment, the switch module 2 includes: a first switch K1 and an intermediate relay;

[0045] The first terminal of the first switch K1 is connected to the AC power supply, the second terminal is connected to the first terminal of the coil of the intermediate relay, and the control terminal is connected to the controller, which is used to close the switch based on the controller when the current value is greater than the preset current threshold.

[0046] The second end of the coil of the intermediate relay is connected to the neutral wire, the first end of the contact of the intermediate relay is connected to the AC power supply, and the second end of the contact of the intermediate relay is connected to the second end of the main contact of the brake contactor, which is used to disconnect when the first switch K1 is closed.

[0047] In this invention, since the switch module 2 needs to be turned on or off according to the control of the controller, the solution uses a first switch K1 and an intermediate relay as the switch module 2. The first switch K1 is set on the power supply circuit of the coil of the intermediate relay. Therefore, the controller can control the opening or closing of the first switch K1 to control the gain or loss of power to the coil of the intermediate relay, thereby controlling the closing or closing of the contacts of the intermediate relay, ensuring the integrity of the solution.

[0048] As an optional embodiment, the switch module 2 includes: a circuit breaker with a trip unit and a second switch K2;

[0049] The first terminal of the second switch K2 is connected to the AC power supply, the second terminal is connected to the first terminal of the circuit breaker coil, and the control terminal is connected to the controller, which is used to close the circuit based on the controller when the current value is greater than the preset current threshold.

[0050] The first terminal of the circuit breaker's trip unit is connected to the AC power supply, the second terminal of the circuit breaker's trip unit is connected to the second terminal of the main contact of the brake contactor, and the second terminal of the circuit breaker's coil is connected to the neutral wire, which is used to disconnect when the second switch K2 is closed.

[0051] In this invention, because the switch module 2 needs to be opened or closed according to the control of the controller, this solution uses a circuit breaker with a trip unit and a second switch K2 as the switch module 2. The second switch K2 is set on the power supply circuit of the circuit breaker coil. Therefore, the controller can control the opening or closing of the second switch K2 to control the gain or loss of power to the circuit breaker coil, thereby controlling the closing or closing of the circuit breaker's trip unit. In addition, compared with switch devices with contacts, the circuit breaker with a trip unit will not experience contact sticking, thus ensuring that it can be closed or closed in a timely manner based on the indirect control of the controller, improving the reliability of the solution.

[0052] It should be noted that the coil voltage of the circuit breaker with a trip unit is AC 220V. The logic judgments in the PLC cabinet program are as follows: Judgment 1: Brake contactor contact sticking judgment. If the PLC program stops outputting the brake open command, and after a 2-second delay, if it detects that the brake contactor is still in the engaged state, it outputs a signal to energize the coil of the circuit breaker with a trip unit, and simultaneously issues a tilt stop command. That is, when the PLC cabinet stops outputting an electrical signal to the brake contactor coil, if the brake contactor contacts are still engaged, it is determined that the brake contactor contacts are sticking. At this time, it is necessary to set the circuit breaker with a trip unit to energize the coil. The circuit breaker coil of the trip unit is energized, thus disconnecting the circuit breaker equipped with the trip unit; Judgment 2: Brake contactor contact contact adhesion judgment. After the PLC cabinet issues a tilting stop command, if the brake contactor is still in the energized state after a 4-second delay, an output signal is issued to energize the trip coil, and a tilting stop command is issued simultaneously; Judgment 3: Inverter output current abnormality judgment. During tilting operation, if the output current of any inverter is detected to be greater than 550A (preset current threshold) and remains so for 3 seconds, an electrical signal is issued to energize the coil of the circuit breaker equipped with the trip unit, and a tilting stop command is issued simultaneously. With this implementation, multiple judgments can be achieved through the PLC program. Abnormal judgment parameters are easily optimized. The time and current values ​​in the program are optimized to the optimal level based on the actual situation. On the one hand, this solves the problem of tilting loss of control caused by brake contactor contact contact adhesion. On the other hand, through program judgment, when the inverter control malfunctions, the main brake circuit (the power supply circuit of the brake motor) is immediately cut off, and the brake is immediately engaged.

[0053] It should also be noted that in practical applications, the tilting motor has a power of 200KW, an instantaneous starting current of about 450A, and a normal operating current of about 180A. The abnormal output current judgment of the inverter in this application is to judge whether the output current of the frequency converter is greater than 550A (preset current threshold) and remains so for 3 seconds.

[0054] As an optional embodiment, it also includes:

[0055] The protection device has its first terminal connected to the AC power supply and its second terminal connected to the first terminal of the second switch K2. It is used to disconnect the circuit when an overvoltage and / or overcurrent occurs in the circuit containing the circuit breaker coil.

[0056] In this invention, considering that the circuit breaker cannot switch normally between opening and closing if overvoltage and / or overcurrent occurs in the power supply circuit of the circuit breaker coil, this solution adds a protection device that disconnects the circuit when overvoltage and / or overcurrent occurs in the circuit containing the circuit breaker coil, so as to ensure the stability of the power supply circuit of the circuit breaker coil.

[0057] It should be noted that in practical applications, the protective device can be a fuse or a circuit breaker, etc., and this application does not make any special limitation.

[0058] As an optional embodiment, it also includes:

[0059] The thermal relay has a heating element connected to the stator of the brake motor. Its normally closed contacts are connected to the first end of the main contacts of the brake contactor and the brake motor, respectively. It is used to disconnect when the temperature of the stator of the brake motor exceeds a first preset temperature threshold.

[0060] In this invention, considering that the temperature of the brake motor affects its control effect on the electro-hydraulic actuator, if the temperature of the brake motor is too high, it may lose control of the electro-hydraulic actuator, causing the converter tilting equipment to fail to stop. Therefore, this solution also sets a thermal relay in the power supply circuit of the brake motor. The heating element of the thermal relay is connected to the stator of the brake motor. When the temperature of the stator of the brake motor is too high, the heating element deforms, thereby pushing the internal guide rod to disconnect the power supply circuit of the brake motor, thus improving the safety and reliability of the solution.

[0061] As an optional embodiment, the first end of the auxiliary contact of the brake contactor is connected to a DC power supply, and the second end of the auxiliary contact of the brake contactor is connected to a low potential point of the controller, so that the switch module 2 is disconnected based on the control of the controller when the brake coil is de-energized and the brake auxiliary contact is closed.

[0062] In this invention, considering that when the brake contactor becomes stuck, the controller cannot control the brake contactor to turn off, and if the converter tilting equipment continues to rotate, molten steel will spill out. Therefore, this solution also connects the auxiliary contacts of the brake contactor to the DC power supply and the low potential point of the controller, respectively. This is because the opening and closing of the main contacts and auxiliary contacts of the brake contactor are synchronized. For example, if the brake contactor is not stuck, after the controller stops sending electrical signals to the brake contactor coil, the main contacts and auxiliary contacts of the brake contactor... All contacts should be disconnected; similarly, if the brake contactor becomes stuck, after the controller stops sending electrical signals to the brake contactor coil, the main contacts and auxiliary contacts of the brake contactor will still be closed. Therefore, the controller can determine whether the brake contactor is stuck based on the gain / loss of power of the brake contactor coil and the state of the auxiliary contacts. If the brake contactor is found to be stuck, the control switch module 2 will be disconnected, thereby disconnecting the power supply circuit of the brake motor and controlling the converter tilting equipment to stop rotating in time, thus avoiding the occurrence of molten steel spillage.

[0063] As an optional embodiment, it also includes:

[0064] An adhesion detection device is installed within a preset range from the tilting brake contactor. The output of the adhesion detection device is connected to the controller to detect whether the brake contactor is sticking, so that the switch module 2 can disconnect based on the controller's control when the brake contactor is sticking.

[0065] In this invention, considering that when the brake contactor becomes stuck, the controller cannot control the brake contactor to shut off, and if the converter tilting equipment continues to rotate, molten steel will spill out. Therefore, this solution adds a sticking detection device. The sticking detection device detects whether the brake contactor is stuck. When the sticking detection device detects that the brake contactor is stuck, the controller can promptly control the switch module 2 to disconnect, thereby disconnecting the power supply circuit of the brake motor and promptly controlling the converter tilting equipment to stop rotating, thus preventing molten steel from spilling out.

[0066] As an optional embodiment, the adhesion detection device includes:

[0067] A vision sensor is installed within a preset range from the brake contactor. The output of the vision sensor is connected to the controller to acquire a preset visual image of the arc-extinguishing cover of the brake contactor, so that the switch module 2 disconnects based on the controller's control when the vision sensor acquires the preset visual image.

[0068] In this invention, considering that when the brake contactor becomes stuck, the arc extinguishing cover of the brake contactor will be damaged, and an unextinguished arc will remain in the arc extinguishing cover, which will lead to the contact of the brake contactor being welded together, this solution adds a vision sensor. The vision sensor acquires the image of the arc extinguishing cover of the brake contactor in real time. When the acquired image of the arc extinguishing cover shows damage or an unextinguished arc, the controller will determine that the brake contactor is stuck. The controller can then promptly control the switch module 2 to disconnect, thereby disconnecting the power supply circuit of the brake motor and controlling the converter tilting device to stop rotating in time, thus avoiding the occurrence of molten steel spillage.

[0069] As an optional embodiment, the adhesion detection device includes:

[0070] A temperature detection device is installed within a preset range from the brake contactor. The output of the temperature detection device is connected to the controller to collect the current temperature of the brake contactor so that the switch module 2 can disconnect based on the controller's control when the current temperature is greater than a second preset temperature threshold.

[0071] In this invention, considering that when the brake contactor becomes stuck, the contact of the brake contactor will experience a significant increase in temperature due to continuous energization, this solution adds a temperature detection device. The temperature detection device detects the temperature of the brake contactor. When the temperature of the brake contactor exceeds the second preset temperature threshold, the controller determines that the brake contactor is stuck. The controller can then promptly control the switch module 2 to disconnect, thereby disconnecting the power supply circuit of the brake motor and stopping the converter tilting device from rotating, thus preventing molten steel from spilling.

[0072] As an optional embodiment, the adhesion detection device includes:

[0073] A sound sensor is installed within a preset range from the brake contactor. The output of the sound sensor is connected to the controller to collect electromagnetic noise at the brake contactor, so that the switch module 2 can disconnect based on the controller's control when the sound sensor collects electromagnetic noise.

[0074] In this invention, considering that when the brake contactor becomes stuck, if the coil of the brake contactor is de-energized, the contacts of the brake contactor will not disconnect, and there will be continuous electromagnetic noise near the contacts, this solution adds a sound sensor. The sound sensor collects the electromagnetic noise at the brake contactor. When the sound sensor continuously collects electromagnetic noise, the controller will determine that the brake contactor is stuck. The controller can then promptly control the switch module 2 to disconnect, thereby disconnecting the power supply circuit of the brake motor and stopping the converter tilting device from rotating, thus preventing molten steel from spilling.

[0075] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0076] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A protection system, characterized in that, include: The device includes a current acquisition device, a switch module, and a converter vanadium extraction equipment. The converter vanadium extraction equipment includes: a frequency converter, a tilting motor, a converter vanadium extraction device, and a tilting brake. The tilting brake includes: a brake contactor, a brake motor, and an electro-hydraulic actuator. A current acquisition device, wherein the acquisition end of the current acquisition device is connected to the output end of the frequency converter, and the output end is connected to the controller, for acquiring the current value of the output end of the frequency converter; The output end of the frequency converter is connected to the converter tilting device through the tilting motor; The first end of the main contact of the brake contactor is connected to the electro-hydraulic actuator through the brake motor, and the first end of the coil of the brake contactor is connected to the controller, and the second end is connected to the neutral wire; The first end of the switch module is connected to an AC power source, the second end is connected to the second end of the main contact of the brake contactor, and the control end is connected to the controller, which is used to disconnect the switch based on the controller's control when the current value is greater than a preset current threshold.

2. The protection system as described in claim 1, characterized in that, The switching module includes: a first switch and an intermediate relay; The first terminal of the first switch is connected to the AC power supply, the second terminal is connected to the first terminal of the coil of the intermediate relay, and the control terminal is connected to the controller, for closing the switch based on the controller when the current value is greater than a preset current threshold. The second end of the coil of the intermediate relay is connected to the neutral wire, the first end of the contact of the intermediate relay is connected to the AC power supply, and the second end of the contact of the intermediate relay is connected to the second end of the main contact of the brake contactor, for disconnection when the first switch is closed.

3. The protection system as described in claim 1, characterized in that, The switching module includes: a circuit breaker with a trip unit and a second switch; The first terminal of the second switch is connected to the AC power supply, the second terminal is connected to the first terminal of the circuit breaker coil, and the control terminal is connected to the controller, for closing the switch based on the controller's control when the current value is greater than a preset current threshold. The first end of the circuit breaker's trip unit is connected to the AC power supply, the second end of the circuit breaker's trip unit is connected to the second end of the main contact of the brake contactor, and the second end of the circuit breaker's coil is connected to the neutral wire for disconnection when the second switch is closed.

4. The protection system as described in claim 3, characterized in that, Also includes: The protection device has a first end connected to the AC power supply and a second end connected to the first end of the second switch, and is used to disconnect when an overvoltage and / or overcurrent occurs in the circuit where the coil of the circuit breaker is located.

5. The protection system as described in claim 1, characterized in that, Also includes: A thermal relay, wherein the heating element of the thermal relay is connected to the stator of the brake motor, and the normally closed contacts are connected to the first end of the main contacts of the brake contactor and the brake motor respectively, and is used to disconnect when the temperature of the stator of the brake motor is greater than a first preset temperature threshold.

6. The protection system according to any one of claims 1 to 5, characterized in that, The first end of the auxiliary contact of the brake contactor is connected to a DC power supply, and the second end of the auxiliary contact of the brake contactor is connected to the low potential point of the controller, so that the switching module disconnects based on the control of the controller when the coil of the brake is de-energized and the auxiliary contact of the brake is closed.

7. The protection system according to any one of claims 1 to 5, characterized in that, Also includes: An adhesion detection device is installed within a preset range from the tilting brake contactor. The output of the adhesion detection device is connected to the controller and is used to detect whether the brake contactor is sticking, so that the switch module can disconnect under the control of the controller when the brake contactor is sticking.

8. The protection system as described in claim 7, characterized in that, The adhesion detection device includes: A vision sensor is installed within a preset range from the brake contactor. The output of the vision sensor is connected to the controller to acquire a preset visual image of the arc-extinguishing cover of the brake contactor, so that the switch module disconnects based on the control of the controller when the vision sensor acquires the preset visual image.

9. The protection system as described in claim 7, characterized in that, The adhesion detection device includes: A temperature detection device is installed within a preset range from the brake contactor. The output of the temperature detection device is connected to the controller to collect the current temperature of the brake contactor, so that the switch module disconnects based on the control of the controller when the current temperature is greater than a second preset temperature threshold.

10. The protection system as described in claim 7, characterized in that, The adhesion detection device includes: A sound sensor is installed within a preset range from the brake contactor. The output of the sound sensor is connected to the controller and is used to collect electromagnetic noise at the brake contactor so that the switch module disconnects based on the control of the controller when the sound sensor collects the electromagnetic noise.

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