An all-fiber pull-cord switch and transmission equipment fault location and early warning system

Abstract

The present application discloses an all-fiber pull-string switch and a transmission equipment fault location and warning system. The all-fiber pull-string switch includes a single-wavelength laser, an optical pulse modulator, a light detector, a fiber coupler, a signal processor, and a microstructured optical fiber. The single-wavelength laser is connected to one end of the optical pulse modulator, the other end of the optical pulse modulator is connected to the input end of the fiber coupler, the first output end of the fiber coupler is connected to the microstructured optical fiber, and the second output end is connected to one end of the light detector. The other end of the light detector is connected to the signal processor. The microstructured optical fiber is arranged on both sides of the transmission equipment along the transmission direction. The present invention uses microstructured optical fiber to reduce the complexity and cost of the system. It has good stability and corrosion resistance, can be used in extreme environments, and does not require electrical transmission, so it is not prone to safety risks. It can quickly determine the operating status of the transmission equipment and accurately locate the fault point.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fiber sensing and automatic control, and in particular relates to an all-optical fiber pull-rope switch and a transmission equipment fault location and early warning system. Background Art

[0002] Conveyor belts and other conveying equipment are key for the long-distance transportation of various materials and components. They are widely used in mining, civil engineering, and industrial fields. However, due to their long-term high-speed and heavy-load operation, conveyor belts are prone to transportation failures such as belt breakage, deviation, and overheating. To ensure transportation safety, pull-cord switches are usually installed on both sides of conveyor belts and other conveying equipment, and inspectors are arranged to conduct manual inspections along the transportation lines. During the inspection process, if a conveyor belt fails or an emergency situation occurs, the inspector can simply pull the pull cords at both ends of the conveyor belt to trigger the control signal for the belt switch, thereby alarming and emergency braking the conveyor belt and other conveying equipment, and reporting the location of the failure.

[0003] Existing conveying equipment such as belt conveyors are usually equipped with electrical pull-rope switches on both sides, which have the following problems: First, electrical pull-rope switches need to be fully energized to maintain working status. Therefore, when used in conveying equipment in high-risk environments such as high-concentration gas, the risk of accidents is very high; Second, due to cost and wiring complexity considerations, electrical pull-rope switches are generally arranged at intervals of 50 meters. Their spatial positioning resolution is not high and they cannot accurately locate the actual fault location of the conveying equipment; Third, for conveying equipment over dozens or even hundreds of kilometers, a large number of electrical pull-rope switches need to be deployed, which involves complex wiring methods and control signals, increasing the complexity and safety risks of the system and the site.

[0004] Therefore, it is necessary to propose an all-fiber optic pull-wire switch and a transmission equipment fault location and warning system to solve the technical problems of large electromagnetic interference, low fault location accuracy, complex system and high cost in the existing technology of transmission equipment monitoring systems such as belt conveyors using electrical pull-wire switches. Summary of the Invention

[0005] The present invention provides an all-fiber pull-cord switch and a transmission equipment fault location and warning system, which are used to solve the technical problems of electrical pull-cord switches in the prior art, such as large electromagnetic interference, high use risk, low fault location accuracy, complex wiring and high cost.

[0006] To solve the above problems, the present invention provides an all-fiber pull-rope switch for use in a transmission system, comprising: a single-wavelength laser, an optical pulse modulator, a light detector, a fiber coupler, a signal processor, and a microstructured optical fiber; the single-wavelength laser is connected to one end of the optical pulse modulator, the other end of the optical pulse modulator is connected to the input end of the fiber coupler, the first output end of the fiber coupler is connected to the microstructured optical fiber, and the second output end is connected to one end of the light detector; the other end of the light detector is connected to the signal processor; wherein the microstructured optical fibers are arranged on both sides of the transmission device along the transmission direction;

[0007] The single-wavelength laser is used to emit continuous light of a single wavelength;

[0008] The optical pulse modulator is used to modulate the continuous light into pulse light;

[0009] The optical fiber coupler is used to transmit the pulsed light to the microstructured optical fiber, receive the reflected light signal reflected by the microstructured optical fiber, and transmit the reflected light signal to the optical detector;

[0010] The light detector is used to convert the reflected light signal into an electrical signal;

[0011] The signal processor is used to detect the electrical signal and determine the working status of the transmission equipment and locate the fault location based on the detection result.

[0012] Furthermore, the microstructured optical fiber comprises a plurality of equidistant microstructured light reflection points distributed along the transmission direction of the optical signal, each microstructured light reflection point being used to reflect the incident light; the microstructured optical fiber reflects the pulsed light into a plurality of reflected light signals.

[0013] Furthermore, the microstructured optical fiber is fixed on both sides of the transmission device according to the spacing between the microstructured light reflection points.

[0014] Furthermore, the microstructured light reflection points are weakly reflective fiber gratings, and the distance between two adjacent microstructured light reflection points is more than twice the resolution of the optical signal that can be processed by the optical detector.

[0015] Furthermore, the wavelength range of the continuous light satisfies all optical wavelengths supported by single-mode transmission and low-loss transmission in the microstructure optical fiber, and the wavelength range is within the reflection wavelength bandwidth of the microstructure light reflection point.

[0016] Furthermore, the signal processor includes a calculation module and a judgment module;

[0017] The calculation module is used to determine the amount of reflected light and the pulse interval in the electrical signal;

[0018] The judgment module is used to judge whether the transmission device fails according to the amount of the reflected light and the pulse interval.

[0019] Furthermore, the signal processor further includes a positioning module;

[0020] The positioning module is used to determine the fault location of the transmission device according to the amount of the reflected light and the pulse interval when the transmission device fails.

[0021] Furthermore, the signal processor is also connected to the optical pulse modulator for controlling the optical pulse modulator.

[0022] Furthermore, the single-wavelength laser, optical pulse modulator, optical detector and optical fiber coupler are connected by ordinary single-mode optical fiber.

[0023] The present invention also provides a transmission equipment fault location and warning system, comprising: a transmission equipment, a pull-wire switch, a state control switch, and an alarm. The pull-wire switch adopts any one of the all-fiber pull-wire switches described in the above technical solution:

[0024] The signal processor of the pull-cord switch is electrically connected to the transmission device, the state control switch and the alarm, and the state control switch is electrically connected to the transmission device;

[0025] The pull-cord switch is used to receive fault signals, determine fault location information of the transmission equipment, send shutdown signals and start signals to the state control switch, and send alarm signals to the alarm;

[0026] The state control switch is used to shut down the transmission device according to the shutdown signal, and is also used to start the transmission device according to the start signal;

[0027] The alarm is used to display the fault location information and emit an audible and visual alarm according to the alarm signal.

[0028] Compared with the prior art, the present invention has the following beneficial effects: the all-fiber pull-cord switch provided by the present invention arranges microstructured optical fibers on both sides of the transmission equipment along the transmission direction, generates single-wavelength continuous light through a single-wavelength laser, modulates the continuous light into pulsed light through an optical pulse modulator, and the microstructured optical fiber reflects the pulsed light to produce a reflected light signal. The reflected light is received by an optical detector and converted into an electrical signal. Finally, the electrical signal is analyzed by a signal processor to determine whether the transmission equipment is faulty and locate the fault location. The present invention replaces the independent electrical pull-cord switches and thousands of wires in the traditional pull-cord switch system with a whole microstructured optical fiber cable, greatly reducing the complexity of the system and reducing the cost of use. The pull-cord switch uses microstructured optical fibers, which have good stability and corrosion resistance, can be used in extreme environments, and do not require electrical transmission, so they are not prone to safety risks. The signal processor analyzes the reflected light signal generated by the microstructured optical fiber to quickly determine the working status of the transmission equipment and accurately locate the fault point. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic structural diagram of an embodiment of an all-fiber pull-cord switch provided by the present invention;

[0030] Figure 2 A schematic structural diagram of an embodiment of a microstructured optical fiber cable provided by the present invention;

[0031] Figure 3 A schematic diagram of the working process of an embodiment of an all-fiber pull-cord switch provided by the present invention;

[0032] Figure 4 A transmission equipment fault location and early warning system provided by the present invention shows a reflected light signal diagram before and after a maintenance worker pulls the optical cable when a fault occurs in the equipment;

[0033] Among them, 1-single wavelength laser, 2-optical pulse modulator, 3-photodetector, 4-signal processor, 5-fiber coupler, 6-microstructured optical fiber, 7-transmission equipment, 61-light reflection point, 62-optical fiber core, 63-optical fiber cladding, 64-armor and plastic protective layer. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0035] Before describing the embodiments, the inventive concept of the present application is first explained.

[0036] Existing conveyor belts and other conveying equipment typically have electrical pull-rope switches installed on both sides. Due to cost and wiring complexity considerations, these switches are typically installed every 50 meters. In the event of a conveyor failure or emergency, inspectors must pull the steel rope between two adjacent switches, triggering a signal to control the belt's operation, thereby alarming and braking the conveyor. However, these electrical switches must remain energized at all times, making them prone to accidents in environments with high gas concentrations. Furthermore, the distance between pull-rope switches is long, resulting in low fault location resolution. This makes switch deployment complex and costly for controlling large conveyor equipment.

[0037] Based on the fiber Bragg grating principle, the present invention provides an all-fiber pull-string switch, which replaces multiple traditional independent electrical pull-string switches and thousands of wires with a whole microstructured optical fiber, greatly reducing the complexity of the transmission equipment control system. In addition, the present invention does not require power supply, has good system stability, a high safety factor, high fault location accuracy, and low cost.

[0038] The embodiment of the present invention provides an all-fiber pull-wire switch, which is applied to a transmission system, such as Figure 1 As shown, including:

[0039] A single-wavelength laser 1, an optical pulse modulator 2, a light detector 3, a fiber coupler 5, a signal processor 4, and a microstructured optical fiber 6; the single-wavelength laser 1 is connected to one end of the optical pulse modulator 2, the other end of the optical pulse modulator 2 is connected to the input end of the fiber coupler 5, the first output end of the fiber coupler 5 is connected to the microstructured optical fiber 6, and the second output end is connected to one end of the light detector 3; the other end of the light detector 3 is connected to the signal processor 4; wherein the microstructured optical fibers 6 are arranged on both sides of the transmission device 7 along the transmission direction;

[0040] The single-wavelength laser 1 is used to emit continuous light of a single wavelength;

[0041] The optical pulse modulator 2 is used to modulate the continuous light into pulse light;

[0042] The optical fiber coupler 5 is used to transmit the pulsed light to the microstructured optical fiber 6, receive the reflected light signal reflected by the microstructured optical fiber 6, and transmit the reflected light signal to the optical detector 3;

[0043] The light detector 3 is used to convert the reflected light signal into an electrical signal;

[0044] The signal processor 4 is used to detect the electrical signal, and determine the working status of the transmission device 7 and locate the fault location based on the detection result.

[0045] The working principle of the all-fiber pull-cord switch provided in this embodiment is as follows:

[0046] Single-wavelength laser 1 emits continuous light at a single wavelength, which is then modulated into pulsed light by optical pulse modulator 2. The pulsed light enters microstructured optical fiber 6 through the first output end of optical fiber coupler 5, where it is reflected as reflected light. The reflected light then enters optical detector 3 through the second output end of optical fiber coupler 5, where it is converted into an electrical signal and sent to signal processor 4. Signal processor 4 analyzes the status of transmission device 7 and, if a fault signal is detected, locates the fault.

[0047] This embodiment provides an all-fiber pull-cord switch. Microstructured optical fibers are arranged on both sides of a transmission device along the transmission direction. A single-wavelength laser generates continuous light at a single wavelength, which is modulated into pulsed light by an optical pulse modulator. The microstructured optical fiber reflects the pulsed light, producing a reflected light signal. A photodetector receives the reflected light and converts it into an electrical signal. Finally, a signal processor analyzes the electrical signal to determine whether the transmission device is faulty and locate the fault. The all-fiber pull-cord switch provided by this embodiment replaces the individual electrical pull-cord switches and thousands of wires in a traditional pull-cord switch system with a single microstructured optical fiber cable, significantly reducing system complexity and operating costs. The pull-cord switch utilizes microstructured optical fibers, which offer excellent stability and corrosion resistance, making it suitable for use in extreme environments. The switch also operates without electrical transmission, posing less risk to safety. The signal processor analyzes the reflected light signal generated by the microstructured optical fiber, enabling rapid determination of the transmission device's operating status and precise location of the fault.

[0048] As a preferred embodiment, the microstructured optical fiber 6 includes a plurality of equidistant microstructured light reflection points distributed along the optical signal transmission direction, each microstructured light reflection point is used to reflect the incident light; the microstructured optical fiber 6 reflects the pulsed light into a plurality of reflected light signals.

[0049] As a specific embodiment, the microstructured optical fiber 6 includes N equidistant microstructured light reflection points distributed along the optical fiber. Each microstructured light reflection point modulates the incident signal light in the optical fiber into a specific reflected signal light. When the transmission equipment is operating normally, a total of N reflected signal lights are generated. Monitoring the spectrum of the reflected signal light will form a reflection peak to verify the distance distribution.

[0050] In order to improve the tensile strength of the optical fiber pull rope switch and protect the microstructured optical fiber, as a specific embodiment, the microstructured optical fiber is made into a microstructured optical fiber cable through tight sleeve, armoring and other processes. Figure 2 As shown, Figure 2This is a detailed diagram of the microstructured optical fiber cable of the all-fiber pull-rope switch and positioning warning system in this example, including a microstructured light reflection point 61, which is used to modulate the incident signal light into reflected signal light; the optical fiber core 62 and the optical fiber cladding 63, which are used together to bind the incident signal light and the reflected signal light in the optical fiber for transmission; and the armor and plastic protective layer 64, which are used to enhance the toughness of the microstructured optical fiber cable and prevent the microstructured optical fiber cable from breaking during the operation of the conveyor.

[0051] As a preferred embodiment, the microstructured optical fiber is fixed on both sides of the transmission device according to the spacing between the microstructured light reflection points.

[0052] As a preferred embodiment, the microstructured light reflection points are weakly reflective fiber Bragg gratings, and the distance between two adjacent microstructured light reflection points is more than twice the optical signal resolution that can be processed by the optical detector.

[0053] As a specific embodiment, the microstructure light reflection points of the microstructure optical fiber can be weak reflection fiber gratings, or highly doped optical fiber segments. The weak reflection fiber gratings are continuously inscribed on the optical fiber by laser exposure, and the spacing between adjacent microstructure light reflection points is generally greater than 1 meter.

[0054] As a preferred embodiment, the wavelength range of the single-wavelength continuous light meets all light wavelengths of single-mode transmission and low-loss transmission modes in the microstructure optical fiber, and the wavelength range is within the reflection wavelength bandwidth of the microstructure light reflection point.

[0055] As a specific embodiment, the bandwidth range of the single-wavelength laser is less than 1 nm and is within the reflection bandwidth range of the microstructure light reflection point of the microstructure optical fiber cable.

[0056] As a preferred embodiment, the signal processor includes a calculation module and a judgment module;

[0057] The calculation module is used to determine the amount of reflected light and the pulse interval in the electrical signal;

[0058] The judgment module is used to judge whether the transmission device fails according to the amount of the reflected light and the pulse interval.

[0059] As a preferred embodiment, the signal processor further includes a positioning module;

[0060] The positioning module is used to determine the fault location of the transmission device according to the amount of the reflected light and the pulse interval when the transmission device fails.

[0061] As a preferred embodiment, the signal processor 4 is further connected to the optical pulse modulator 2 and the transmission device 7 to control the optical pulse modulator 2 and the operating state of the transmission device 7 .

[0062] As a specific embodiment, when the inspection personnel find that the working transmission equipment has failed, they pull the microstructured optical fiber cable. The microstructured light reflection point is subjected to stress, and its reflection wavelength will drift and deviate from the reflection working range. It is not within the wavelength range of the incident laser. At this time, the microstructured light reflection point at the fault location will not generate a pulsed reflected light signal. By counting the pulsed reflected light and analyzing the pulse interval, the transmission equipment failure can be determined, and positioning, reservation and emergency braking can be achieved.

[0063] The above process is further illustrated below using a specific numerical example.

[0064] In this example, the incident light emitted by the single-wavelength laser 1 has a central wavelength of 1550 nm and a 3dB bandwidth of 0.5 nm. The central reflection wavelength of the microstructured sensing unit of the microstructured optical fiber 6 is 1550 nm, and the 3dB reflection bandwidth is 2 nm. Microstructured optical fiber cables are laid on both sides of the conveyor belt, with a fixed spacing consistent with the spacing between the microstructured light reflection points. When the conveyor is operating normally, the microstructured light reflection points consistently reflect the 1550 nm optical signal. Each sensor unit reflects the modulated pulsed incident light, generating a pulsed reflected light signal, resulting in the presence of each reflection peak. When the conveyor malfunctions, the microstructured light reflection points are stressed by the microstructured optical fiber cable, causing their reflected operating wavelength to drift, falling outside the wavelength range of the incident light. At this point, the microstructured light reflection point at the fault location will not generate a pulsed reflected light signal, and the reflection peak at the corresponding point will disappear. By counting the pulsed reflected light and analyzing the pulse intervals, a signal processor can determine the conveyor equipment malfunction and implement positioning, pre-determining, and emergency braking.

[0065] As a preferred embodiment, the single-wavelength laser, optical pulse modulator, optical detector and optical fiber coupler are connected by ordinary single-mode optical fiber.

[0066] The present invention also provides a transmission equipment fault location and warning system, comprising: a transmission equipment, a pull-wire switch, a state control switch, and an alarm. The pull-wire switch adopts any one of the all-fiber pull-wire switches described in the above technical solution:

[0067] The signal processor of the pull-cord switch is electrically connected to the transmission device, the state control switch and the alarm, and the state control switch is electrically connected to the transmission device;

[0068] The pull-cord switch is used to receive fault signals, determine fault location information of the transmission equipment, send shutdown signals and start signals to the state control switch, and send alarm signals to the alarm;

[0069] The state control switch is used to shut down the transmission device according to the shutdown signal, and is also used to start the transmission device according to the start signal;

[0070] The alarm is used to display the fault location information and emit an audible and visual alarm according to the alarm signal.

[0071] like Figure 3 As shown, Figure 3 This is the workflow diagram of the transmission equipment fault location and warning system in this example. A single-wavelength laser generates laser light, which is modulated into pulsed light by an optical pulse modulator. The optical detector then receives the pulsed reflected light. The signal processor performs peak search on all pulses received within a single time period, finding the number of pulses n. If the number of pulses n is equal to the number of microstructure sensing units N in the microstructure optical fiber, the conveyor belt is operating normally. Otherwise, it indicates that the conveyor belt has a fault. The signal processor sends a stop command to the conveyor belt and begins searching for the fault location. Calculate the distance interval δ between the mth pulse and the m+1th pulse. m , and compare it with the distance interval Δ obtained by calibration under normal working conditions m For comparison, if δ m With Δ m If the difference between the two is greater than the set threshold d, it indicates that there is a fault at that location, and the alarm displays the fault and the fault location information. If this pulse does not correspond to the last microstructure sensor unit and m is not equal to n, the next location is detected for faults, and the detection ends when m equals n. The alarm displays all fault information.

[0072] When a conveying device such as a belt conveyor breaks down, maintenance personnel pull the optical cable. Figure 4 As shown, Figure 4 This image shows the reflected light signals from the signal processor before and after the maintenance worker pulled the pull-cord switch. Before the fault, all reflected light signals were spaced at the same interval. After the fault, the reflected light signal originally located at 580 meters disappeared. By comparing the distances of adjacent reflected light signals, the fault was determined to be present at that location.

[0073] This embodiment provides an all-fiber pull-cord switch and transmission equipment fault location and warning system, in which microstructured optical fibers are arranged on both sides of the transmission equipment along the transmission direction, a single-wavelength continuous light is generated by a single-wavelength laser, and the continuous light is modulated into pulsed light by an optical pulse modulator. The microstructured optical fiber reflects the pulsed light to produce a reflected light signal, which is received by an optical detector and converted into an electrical signal. Finally, the electrical signal is analyzed by a signal processor to determine whether the transmission equipment is faulty and locate the fault location.

[0074] The transmission equipment fault location and warning system provided in this embodiment replaces the independent electrical pull-cord switches and thousands of wires in the traditional pull-cord switch system with a whole microstructured optical fiber cable, greatly reducing the complexity of the system and reducing the cost of use; the pull-cord switch uses microstructured optical fiber, which has good stability and corrosion resistance, can be used in extreme environments, and has no electrical transmission, so it is not easy to cause safety risks; by analyzing the reflected light signal generated by the microstructured optical fiber through the signal processor, the working status of the transmission equipment can be quickly determined and the fault point can be accurately located.

[0075] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. An all-fiber pull-cord switch, used in a transmission system, characterized in that: include: A single-wavelength laser, an optical pulse modulator, a light detector, a fiber coupler, a signal processor, and a microstructured optical fiber; the single-wavelength laser is connected to one end of the optical pulse modulator, the other end of the optical pulse modulator is connected to the input end of the fiber coupler, the first output end of the fiber coupler is connected to the microstructured optical fiber, and the second output end of the fiber coupler is connected to one end of the light detector; the other end of the light detector is connected to the signal processor; wherein the microstructured optical fibers are arranged on both sides of the transmission device along the transmission direction; The single-wavelength laser is used to emit continuous light of a single wavelength; The optical pulse modulator is used to modulate the continuous light into pulse light; The optical fiber coupler is used to transmit the pulsed light to the microstructured optical fiber, receive the reflected light signal reflected by the microstructured optical fiber, and transmit the reflected light signal to the optical detector; The light detector is used to convert the reflected light signal into an electrical signal; The signal processor is used to detect the electrical signal and determine the working status of the transmission equipment and locate the fault location based on the detection result.

2. The all-fiber pull-cord switch according to claim 1, characterized in that: The microstructured optical fiber comprises a plurality of equidistant microstructured light reflection points distributed along the transmission direction of the optical signal, each microstructured light reflection point being used to reflect the incident light; the microstructured optical fiber reflects the pulsed light into a plurality of reflected light signals.

3. The all-fiber pull-cord switch according to claim 2, characterized in that: The microstructured optical fiber is fixed on both sides of the transmission device according to the spacing between the microstructured light reflection points.

4. The all-fiber pull-cord switch according to claim 2, characterized in that: The microstructure light reflection points are weakly reflective fiber gratings, and the distance between two adjacent microstructure light reflection points is more than twice the optical signal resolution that can be processed by the light detector.

5. The all-fiber pull-cord switch according to claim 2, characterized in that: The wavelength range of the continuous light satisfies all optical wavelengths supported by single-mode transmission and low-loss transmission in the microstructure optical fiber, and the wavelength range is within the reflection wavelength bandwidth of the microstructure light reflection point.

6. The all-fiber pull-cord switch according to claim 1, characterized in that: The signal processor includes a calculation module and a judgment module; The calculation module is used to determine the amount of reflected light and the pulse interval in the electrical signal; The judgment module is used to judge whether the transmission device fails according to the amount of the reflected light and the pulse interval.

7. The all-fiber pull-cord switch according to claim 6, characterized in that: The signal processor further includes a positioning module; The positioning module is used to determine the fault location of the transmission device according to the amount of the reflected light and the pulse interval when the transmission device fails.

8. The all-fiber pull-cord switch according to claim 1, characterized in that: The signal processor is also connected to the optical pulse modulator and is used to control the optical pulse modulator.

9. The all-fiber pull-cord switch according to claim 1, characterized in that: The single-wavelength laser, optical pulse modulator, optical detector and optical fiber coupler are connected by using common single-mode optical fiber.

10. A transmission equipment fault location warning system, characterized in that: include: Transmission equipment, a pull-wire switch, a status control switch, and an alarm, wherein the pull-wire switch is any one of the all-fiber pull-wire switches described in claims 1-9: The signal processor of the pull-cord switch is electrically connected to the transmission device, the state control switch and the alarm, and the state control switch is electrically connected to the transmission device; The pull-cord switch is used to receive fault signals, determine fault location information of the transmission equipment, send shutdown signals and start signals to the state control switch, and send alarm signals to the alarm; The state control switch is used to shut down the transmission device according to the shutdown signal, and is also used to start the transmission device according to the start signal; The alarm is used to display the fault location information and emit an audible and visual alarm according to the alarm signal.

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