95results about How to "Strong anti-electromagnetic interference ability" patented technology

The invention relates to an apparatus and a method for detecting a partial discharge of a power transformer by utilizing a fluorescence fiber, more particular to a simulation experiment apparatus and a method thereof for a partial discharge of a needle-board electrode in a power transformer. The apparatus provided in the invention mainly comprises: an induction regulator; a dizziness-free test transformer; a partial discharge protective resistance; a standard capacitance voltage divider; a partial discharge generator, which is formed by a needle-board electrode, a fluorescence fiber and a housing; a photomultiplier; a direct current regulated power supply; and an oscilloscope and the like. According to the method provided in the invention, the apparatus is utilized; and a needle-board electrode partial discharge experiment in the air of a power transformer is simulated. According to the invention, partial discharge experiments of a transformer with different exerted voltages and in different spacings are simulated; besides, the apparatus has advantages of strong anti-interference capability, good insulating property and high detection sensitivity and the like. Moreover, the apparatus and the method can be widely applied to luminous characteristic researches of a power transformer on floating potential partial discharge, insulator surface discharge and partial discharge in a transformer oil and an SF6 of a GIS in the air medium.

A compensation method of current sensor includes real-time detection of magnetic induction density and outputting current with proper phase and magnitude via the feedback circuit for tracking compensation of the exciting current in magnetic core. A zero-flux microcurrent sensor designed based on the method has two superposed annular working magnetic cores and auxiliary magnetic core with wound primary coil, secondary coil and compensating coil as well as shielding and protecting casing outside the magnetic core. The microcurrent sensor features the primary and secondary coils on the superposed core, the secondary coil with load across it, one detection coil on the working core, a compensation coil on the auxiliary core, electronic regulating circuit comprising amplifier and voltage-to-current converter connected between the detection coil and the compensation coil.

The invention relates to a metro tunnel settlement deformation monitoring method based on a distributed fiber sensing technology. The method includes the following steps: (1) determining the relation between displacement value and bending moment distribution according to a displacement curve approximate differential equation; (2) determining a conversion relation between strain and settlement deformation according to a material dynamic conjugation beam method to find an explicit linear equation between the strain and the settlement deformation; (3) finally considering settlement of control points, distributing settlement of the control points to each monitoring point through equal weighted distribution to finally obtain the settlement value of each monitoring point. Compared with the prior art, the method has the advantages of being better in adaptability, reliable in calculation result and the like.

A method for sensing methane in distribution mode based on optical fiber Bragg grating includes coating Pt film with thickness of 1 ¿C 5 micron on said Bragg grating, using metal Pt as catalyst to catalyze methane in outside air and to carry out oxidation reaction with oxygen for converting chemical energy to be heat energy so as to change reflection peak position of said Bragg grating in following change of temperature, confirming methane concentration in gas to be tested by confirming wavelength of reflection peak.

The invention discloses a wavelength division multiplexing device of an optical fiber microphone based on an FP interferometry principle. The wavelength division multiplexing device is characterized in that a laser device formed by an ASE wide-spectrum light source and a dense wavelength division multiplexer (DWDM) and a microphone probe array formed by n microphone probes are included, an output end of the DWDM is respectively connected with ports I of corresponding single-way light guide units through optical fibers, monochromatic light enters the corresponding single-way light guide units through the corresponding ports I of the single-way light guide units and then enters the corresponding microphone probes through ports II of the corresponding single-way light guide units for sound vibration sensing, FP interference light generated by the microphone probes enters the single-way light guide units from the ports II of the single-way light guide units corresponding to the microphone probes and then is emitted out from ports III of the single-way light guide units and enters PIN photodiodes corresponding to the microphone probes. The wavelength division multiplexing device has the advantages of being high in sensitivity and strong in electromagnetic interference resistant capacity, and multiplexing and array forming are easy.

The invention belongs to the technical field of servo driver circuit design, and specifically relates to a double-drive hybrid direct-current and low-voltage intelligent servo driver circuit. The circuit of the invention comprises an ARM-based intelligent control unit, an FPGA-based control unit, a high-speed analog-to-digital conversion unit, a high-speed digital-to-analog conversion unit, a data storage unit, a signal conditioning unit, an external network communication unit, a power management unit, a debugging and simulation unit, a passive crystal oscillation unit, a human-computer interaction unit, a sensor information unit, an intelligent control output unit, a power protection unit, and a power drive unit. The technical problem that the existing servo driver has poor control performance, occupies a large space and is hard to achieve a networked mode is solved. By adopting the design of 'ARM + FPGA + double power drive units', the double-drive hybrid direct-current and low-voltage intelligent servo driver circuit of the invention has the characteristics of double drive, small size, low power consumption, high precision, high reliability, good real-time performance, high scalability, good networking performance, and high resistance to electromagnetic interference.

The invention relates to a system for monitoring the vibration frequency of a high-voltage transmission conductor on line. The system comprises a data acquisition terminal and a data monitoring center, wherein the data acquisition terminal is used for transmitting acquired data information to the data monitoring center through a global system for mobile communications (GSM) network. According to the system, an accurate vibration frequency result can be acquired by the characteristic of high electromagnetic interference resistance of a fiber bragg grating; simultaneously, meteorological data of temperatures, humidity, wind speeds, wind directions and the like in an ambient environment during vibration of the conductor is acquired and is transmitted to the monitoring center through the GSM network which has a wide covering range; and an alarm is given under a bad vibration condition by a vibration characteristic of intelligently recording and analyzing the conductor, and a reference is provided for the design and transformation of subsequent electric power circuits.

The invention relates to an IGBT (insulated gate bipolar translator) temperature detecting method. The method comprises the following steps: firstly, acquiring a voltage signal on an NTC (negative temperature coefficient) thermistor; secondly, converting the voltage signal into a frequency signal by a V-F (voltage-frequency) converting unit; thirdly, converting the frequency signal into an optical signal by a transmitting unit and subsequently transmitting the optical signal to a receiving unit; fourthly, restoring the optical signal into a frequency signal by the receiving unit and subsequently transmitting the frequency signal to a control unit; and fifthly, firstly detecting the frequency of the frequency signal and calculating the IGBT temperature by the control unit so as to accomplish the detection. According to the method, as an optical fiber is adopted to transmit signals, the electromagnetic interference resistance is strong, so that the method is applicable for being used in situations which highly require the anti-electromagnetic interference resistance; by acquiring the voltage of the NTC thermistor, the IGBT temperature can be detected; the real time monitoring function is achieved; the IGBT is prevented from being burned because of overheat; the procedures of the whole method are simplified; the cost of adopted hardware is low; and the application cost is reduced greatly.

The invention relates to an optical fiber-based power transmission line aeolian vibration monitoring digital sensor which comprises an MCU (microprogrammed control unit) computing control unit, wherein the MCU computing control unit is respectively connected with a power supply module and a light sensation module by wires and is sequentially connected with a Zigbee communication module and an upper computer by a Zigbee network. The invention also discloses a monitoring method of the sensor; the method comprises the steps of mounting the power transmission line aeolian vibration monitoring digital sensor on a power transmission line; initializing by the MCU computing control unit, and sequentially performing data acquisition and data processing and outputting an optical fiber phase change electrical signal by the light sensation module; transmitting the optical fiber phase change electrical signal to the MCU computing control unit to obtain an amplitude value and frequency; sending the amplitude value and the frequency to the upper computer by the Zigbee wireless communication module. The sensor disclosed by the invention solves the problems that the existing cantilever beam type aeolian vibration monitoring sensor is poor in frequency response effect and is relatively sensitive to temperature.

The present invention relates to a lens module which comprises a lens base and a barrel fixed on the lens base. The barrel is accommodated with a color filter, a spacing ring and a lens array. The external surface of the lens base is provided with an electromagnetic shielding layer. The electromagnetic shielding layer is a carbon nano-tube / polymer composite material which comprises a polymeric substrate and carbon nano-tube dispersed in the polymeric substrate. The lens array can effectively shield the interference of the external electromagnetic wave to the image sensor thereby increasing the imaging quality.

The invention discloses an intelligent protection net which comprises upright columns and a protection net body arranged in the upright columns. A pull cable is arranged at the top end of the protection net body. Optical fiber sensing devices are arranged between the pull cable and the upright columns. Each fiber sensing device comprises a shell body and an optical fiber bending sensing unit. The shell body is provided with an opening. One end of a moving rod is connected with a slide plate located inside the shell body. Connection devices are arranged on the shell bodies and moving rods located outside the shell bodies and are respectively connected with the upright columns and the pull cable. Each optical fiber bending sensing unit comprises a curve support, a plurality of first deformation teeth and a plurality of second deformation teeth, wherein the plurality of first deformation teeth and the plurality of second deformation teeth are consecutively distributed on the curve support, and a signal optical fiber is clamped between deformation teeth on two sides. An auxiliary spring in parallel connection with each curve support is arranged between each slide plate and the inner wall of each shell body. The signal optical fiber is connected with a testing unit through an optical cable. The testing unit is connected with a processing unit which is connected with a communication alarm unit. The intelligent protection net has the advantages of being high in precision, resistant to electromagnetism interference, and low in cost, and is suitable for actual project environments.

The invention discloses an optical fiber-type tension fence alarm device. The optical fiber-type tension fence alarm device comprises a plurality of flexible bars; one end of each flexible rod is connected with a veridical column 1; the other end of each flexible rod is connected with an optical fiber force measuring device; each optical fiber force measuring device comprises a shell, a movable rod and an optical fiber bending sensor unit; the shell is connected with a veridical column 2; one end of the movable rod extends into the shell and is connected with a sliding plate arranged inside the shell; the other end of the movable rod is arranged outside the shell and is connected with a corresponding flexible rod; the optical fiber bending sensor unit sleeves the movable rod and includes a curved-line-shaped support, a plurality of deformation teeth 1 and a plurality of deformation teeth 2 which are continuously distributed at two opposite sides of the curved-line-shaped support, and a signal optical fiber which is clamped between the deformation teeth 1 and the deformation teeth 2; the signal optical fibers is connected with a test unit; and the test unit is connected with an alarm unit. The optical fiber-type tension fence alarm device of the invention has the advantages of reasonable design, convenient manufacture, low cost, flexible use, high sensitivity, wide dynamic monitoring range and high practical value.

The invention provides a transformer winding deformation on-line monitoring chip. According to the principle of the transformer winding deformation on-line monitoring chip, transformer winding deformation is monitored in an on-line frequency response method. The chip comprises a frequency sweeping signal generator module, a data collection module, a data processing module, a control module, a data storage module and a communication module; the frequency sweeping signal generator module, the data collection module, the data processing module, the data storage module and the communication module are respectively connected with the control module, and the frequency sweeping signal generator module, the data collection module, the data processing module and the data storage module are sequentially connected in a single way. The transformer winding deformation on-line monitoring chip has the advantages of being miniaturized, low in cost, low in power consumption, strong in anti-jamming capability and the like, is an essential method of achieving on-line monitoring, provides core guarantee for safe and reliable operation of a power grid, and is used for a transformer winding deformation monitoring system.

The invention provides a high-performance engine cable assembly, which solves the technical problems of low reliability and short service life of the existing engine cable. The engine cable assembly comprises a main cable, the main cable is divided into a plurality of branch cables through a plurality of bifurcation assemblies, two ends of the main cable and an end of the branch cable are respectively installed with tail accessories; The main cable comprises a main wire harness, and the branch cable comprises a branch wire harness. A polytetrafluoroethylene film is wound on the outer peripheryof the main wire harness and the branch wire harness. A wave-proof sleeve is arranged on the outer periphery of the polytetrafluoroethylene film, and the wave-proof sleeve of the main wire harness iscrimped on the outer periphery of the wave-proof sleeve of the branch wire harness at the bifurcation. The invention has the advantages of high reliability and long service life, and can be used forthe electric connection between the relevant accessories with electric products on the engine and the digital electronic controller and the engine comprehensive diagnostic device, and can transmit thecorresponding electric signals to realize the control function of the engine.

The invention discloses a cable energy-storage multiplex high-voltage pulse generation apparatus. The cable energy-storage multiplex high-voltage pulse generation apparatus comprises a helix pulse generator which is connected to a trigger switch by use of a trigger resistor; a charging cable is connected to the charging interface of the trigger switch; the trigger switch is connected with a blocking capacitor by use of an energy-storage cable; a trigger output cable is connected to the trigger output cable jack of the blocking capacitor. According to the cable energy-storage multiplex high-voltage pulse generation apparatus, the trigger switch discharges by use of the helix pulse generator, the potential of the inner core of the coaxial energy-storage cable changes suddenly, and high-voltage pulses are output via the blocking capacitor; the output pulses are high in rising rate which can be 20kV / ns, low in jittering which does not exceed 2ns, and high in anti-interference capacity, and further can be expanded to multiple outputs easily; the amplitude of the output pulses can be a hundred kV, and the rising time is several nanoseconds; compared with the prior art, the cable energy-storage multiplex high-voltage pulse generation apparatus is obvious in improvement.

The invention relates to a roadway nonlinear deformation prediction method based on fiber bragg grating sensing network data and belongs to roadway surrounding rock nonlinear deformation prediction methods. The method comprises the steps that 1, roadway surrounding rock deformation data is collected based on a fiber bragg grating sensing network; 2, a time sequence of monitoring data of a roadway surrounding rock deformation fiber bragg grating sensor is analyzed and preprocessed; 3, a kernel function and a loss function of a support vector machine are selected, and main parameters of the support vector machine are determined; 4, a kernel function matrix is constructed, and an optimal parameter combination value of the support vector machine is obtained through solving; and 5, a nonlinear support vector machine regression prediction model is established, and roadway surrounding rock nonlinear deformation prediction is realized. According to the method, the fiber bragg grating sensing technology and the support vector machine prediction method are adopted to predict the later-period evolution law and development tendency of a deformed surrounding rock mass, roadway surrounding rock safety monitoring, safety production and construction and stability are guaranteed, and a research direction is provided for intellectualized and informationalized development of mining engineering.

The invention discloses a real-time operation state collection system of a high-voltage mutual inductor group. The system comprises a synchronization module, a collection module, a merging module andan output module; the synchronization module comprises a Beidou / GPS reception module and a synchronization control core module, receives Beidou / GPS signals, provides PPS pulses and a time-service signal, and supports real-time synchronous collection among multiple collection systems; the collection module realizes A / D sampling and characteristic quantity extraction on secondary output electrical analogy signals of groups of mutual inductors; the merging module merges characteristic quantity extraction results of multiple channels, and extracts absolution time from the Beidou / GPS time-service signal; and the output module transmits a collection result to local and remote terminals, and the result can be used to evaluate an operation error of the mutual inductor group in real time. Via the system, operation state data of the groups of mutual inductors in the power grid can be collected synchronously in high precision and in real time, and data basis is provided for evaluation of the operation error of the mutual inductor group.

The invention discloses an intrinsic safety-type dust sensing device used for mining based on a light scattering method. The dust sensing device is characterized by comprising a laser light source (9), a detection cavity (11) and an air blower member which are arranged along same axis, wherein, a light extraction end of the laser light source (9) is communicated with one end of the detection cavity (11), the laser emitted by the laser light source (9) is propagated along the axis, wherein, the intrinsic safety-type dust sensing device also comprises a photoelectric conversion assembly (14), the photoelectric conversion assembly and axis are vertically placed over the detection cavity (11), which faces to a through hole at the upper part of the detection cavity (11), wherein, the air blower member is used for introducing the to-be-measured air into the detection cavity (11).

The invention discloses an impact position judgment method based on full-band amplitude energy and inverse function solving, and belongs to the technical field of impact monitoring for structure health monitoring. The method comprises the following steps: 1, arranging distributed-type FBG (Fiber Bragg Grating) sensors; 2, carrying out the dividing of impact monitoring subregions; 3, selecting a sample impact point, and calculating the response frequency domain amplitude energy of the sample impact point; 4, obtaining a function relation which takes the response frequency domain amplitude energy of the sample impact point as an independent variable and takes the length of an impact point distance positioning sensor as a dependent variable through the inverse function solving; 5, calculating the frequency domain amplitude energy of response signals of to-be-detected impact points; 6, sequentially comparing the frequency domain amplitude energy of response signals of to-be-detected impact points, and determining the monitoring subregions where the to-be-detected impact points are located based on a regional binary search principle; 7, bringing the frequency domain amplitude energy of the to-be-detected impact points into a distance and response signal frequency domain amplitude energy relation, and determining the specific position coordinates of the to-be-detected impact points.

The invention provides a GIS insulation state diagnosis method based on gas component analysis. The GIS insulation state diagnosis method based on gas component analysis comprises the steps that the moisture content inside a GIS gas chamber is measured through a precision mirror plane dew point method; when the moisture content inside the GIS gas chamber meets requirements, varieties and contents of gas decomposition components inside the GIS gas chamber are determined through measurement, and whether electric discharge exists inside GIS equipment or not is judged; if electric discharge exists in the GIS equipment, whether electric discharge in the GIS equipment relates to an organic insulating medium or an inorganic insulating medium is judged according to whether carbonaceous electric-discharge-related gas decomposition components exist inside the GIS equipment. Compared with GIS insulation state diagnosis methods in the past, the GIS insulation state diagnosis method based on gas component analysis has the advantages that the anti-electromagnetic interference performance is better, on-line GIS equipment insulation state diagnosis can be realized, detect type judgment is simpler, and the GIS insulation state diagnosis method is easier to apply and popularize.

The invention relates to a method and a system based on isolated double Ethernet and double CAN communication. The method comprises the following steps of respectively defining a first Ethernet communication channel, a second Ethernet communication channel, a first CAN communication channel and a second CAN communication channel; setting a working channel and a standby channel by judging whether the first Ethernet communication channel and the second Ethernet communication channel are connected normally, and analyzing whether a digital signal transmitted by Ethernet needs to be transmitted bythe first CAN communication channel or the second CAN communication channel; and setting the working channel and the standby channel by judging whether the first CAN communication channel and the second CAN communication channel are connected normally, and analyzing whether the digital signal transmitted by a CAN needs to be transmitted by the first Ethernet communication channel or the second Ethernet communication channel. Compared with the prior art, the method and the system have the advantages of being high in anti-interference capability, easy to expand, high in reliability and the like.

The invention discloses an aluminum-based carbon fiber composite core wire with a real-time temperature measuring function. The aluminum-based carbon fiber composite core wire comprises a core and an aluminum alloy conductor. The core is made by compositing metal aluminum alloy base and carbon fiber material. A plurality of temperature sensing fibers are embedded in the core and are silica fibers with high-temperature resistance. The sensing fibers are coated with modified polyimide coating layers. A copper layer is arranged on the outer surface of the core and covered with pyrolytic carbon layer. The aluminum alloy conductor is hinged around the pyrolytic carbon layer. The aluminum-based carbon fiber composite core wire is anti-electromagnetic interference, high in conductivity, strong in bending strength and extension strength and effective in high-temperature and heat resistance; the temperature sensing fibers serve as sensing elements and transmission signal medium, distributed measurement is achieved, temperature of any positions of the core can be monitored in real time only by adding temperature testing equipment at an interface, and alarm signals are sent out in case of excess temperature.

The invention relates to a high-voltage and large-current harmonics filter for a photovoltaic inverter system. The high-voltage and large-current harmonics filter comprises an iron outer shell, an EMI filtering system and an electric component in an LCL filtering system, wherein the iron outer shell is provided with three copper bar bus inlet wires and three copper bar bus outlet wires, the EMI filtering system is composed of a copper bar bus, a ferrite bead T, a magnetic steel assembly Z, a capacitor C and a resistor R. The EMI filtering system is used for restraining the electromagnetism interference, the LCL filtering system is used for restraining higher harmonics generated by a photovoltaic power generation system, three copper bar buses serve as circuit transmission media, wholly penetrate through the ferrite bead T and the magnetic steel assembly in sequence and are connected with electric points of other electrical components in a riveting mode, the current-carrying capacity can reach to 1,600 A, and the rated voltage is 480 V. The high-voltage and large-current harmonics filter is reasonable and compact in structure, reliable in work, good in stability, capable of effectively meeting and ensuring the using requirement for supplying high-quality electric energy to a social power grid of the photovoltaic power generation system and high in practicality.

The invention discloses a container positioning monitoring terminal based on Beidou communication, and relates to container position monitoring, in particular to a positioning monitoring terminal which is suitable for container position monitoring and can send position information at regular time and send alarm information under abnormal conditions. The terminal comprises: a power supply management module, a Beidou module, a GSM module and a detection module are packaged in a shell. The power management module provides working voltage for the Beidou module, the GSM module and the detection module respectively. The power management module comprises a lithium polymer battery, a power management sub-module and a charging interface. The power management submodule adopts a first power management chip and a second power management chip. The detection module is used for detecting the state of the container door. The GSM module is used for transmitting and receiving a mobile network wireless signal. The Beidou module is used for receiving satellite signals in real time for positioning and sending position information data by using a short message function.

The invention discloses a wireless passive detection system for the tension of a high-voltage transmission line, and the system comprises a tension sensor, a clamping and tension transmission mechanism, and a wireless reader. The tension sensor is installed at a to-be-detected part of the high-voltage transmission line through the clamping and tension transmission mechanism, and is in signal transmission connection with the wireless reader. According to the invention, the system employs a surface transverse wave strain sensitivity theoretical model, integrates the strain sensitivity and a frequency temperature coefficient, and is provided with the dedicated clamping and tension transmission mechanism for measuring the tension of the high-voltage transmission line, wherein the clamping and tension transmission mechanism can be conveniently installed at any detected point on the transmission line, and can prevent the bending moment and torque from affecting the measurement of tension. The wireless reader is used for remotely querying the frequency shift of an STW resonator installed on the transmission line, i.e., obtaining the tension value of a detected point. The wireless reader can be installed on a mobile platform, and can achieve the routing inspection of a surface transverse wave tension sensor at a place which is 10m far.

The invention discloses a torque sensor and a testing system thereof. The torque sensor comprises: a plurality of spokes and two flange plates. Each spoke serves to package one optical fiber grating. The two flange plates are respectively arranged at the two ends of each spoke. Each spoke and flange plate form the same angle, and the plurality of spokes and the two flange plates are processed integratedly, and the plurality of optical fiber gratings packaged by the plurality of spokes are in series connection. By way of the aforementioned method, the torque sensor of the invention, through optical signal parameter operation implemented through optical fiber gratings, has a strong anti-electromagnetic interference capability, small volume, and light weight and is easy to install.

The invention discloses an undersea four-core oil-filled cable which is formed by twisting two insulation line cores, an optical fiber communication cable core and a data line core. A filling layer is arranged at a gap of the cable core. An inner protecting layer, a shielding layer, a water resisting layer, an armor layer and an outer sheath are arranged outside the cable core in sequence. A conductor is of a hollow structure, an oil duct is arranged in the conductor, and a plurality of strengthening cores are arranged at the gap of the cable core after the cable core is twisted. By the undersea four-core oil-filled cable, data transmission and power transmission can be achieved at the same time, the shielding effect is good, the electromagnetic interference resistance capacity is high, the outer diameter of a core wire is small, the level of pressure resistance and the tensile strength are high, high water pressure of deep sea wire distribution of an undersea detecting instrument can be borne, and the working requirements of undersea projects and oil platforms are met. In addition, by the arrangement of the multiple strengthening cores, the cable core of the undersea four-core oil-filled cable is not prone to being broken, and the service life is long.

The invention discloses a low-frequency accelerometer based on a fiber grating. The accelerometer comprises a pedestal, two symmetrical elastic mass assemblies are arranged on the pedestal, each elastic mass assembly comprises a mass block and a bending spring, the mass block is placed under the bending spring, one end of the bending spring is connected with the pedestal, the other end of the bending spring is pressed on the pedestal by the mass block, and the fiber grating is placed on the bending springs and adhered to the bending springs. The bending springs vibrate to enable axial strains in opposite directions at the two ends of the fiber grating, an axial strain sensing mechanism of the fiber grating is utilized to measure the acceleration, and the measuring sensitivity is multiplied. A fiber is used to transmit sensing signals, measurement and transmission are integrated, and the low-frequency accelerometer based on the fiber grating further has the advantages including high sensitivity, high performance in anti-electromagnetic interference, and capability of long-distance monitoring.

The invention discloses an invisible security set which comprises an upper frame, a lower frame and blocking ropes. The upper frame is arranged on an upper edge of a window, and the lower frame is arranged on a lower edge of the window. The blocking ropes are arranged between the upper frame and the lower frame at intervals in a penetrating mode. The upper frame and the lower frame are respectively provided with a plurality of installation holes for the blocking ropes to penetrate through. Arc plates are arranged on the upper frame and the lower frame and located between two adjacent installation holes, and the blocking ropes penetrate through the installation holes in the upper frame and the lower frame at intervals and are wound on the arc plates. The blocking ropes, the upper frame, the lower frame and the arc plates together form a net structure, and the blocking ropes respectively comprise sensing fibers, an inner protective layer and an outer protective layer. The inner protective layers are arranged outside the sensing fibers, and the outer protective layers are arranged outside the inner protective layers. The tail ends of the sensing fibers are connected with a test unit which is connected with an alarm. The invisible security set is fixed on a door and a window or a balcony through the high-strength blocking ropes containing the sensing fibers. Once the blocking ropes break, alarming is sent out, and the protection effect is realized. The invisible security set is convenient to install, low in cost, attractive and elegant, and good in visual effect.

The invention discloses an MEMS inertial switch based on a three-section long inclined beam bistable structure. The switch comprises: a switch housing, a bistable mechanism and a switch auxiliary mechanism. The switch auxiliary mechanism and the bistable mechanism are sequentially arranged inside the switch housing in the acceleration direction, the switch auxiliary mechanism includes a spring body and a first mass, the bistable mechanism comprises a three-section long inclined beam structure and a second mass, a switch contact is provided in the switch housing at a position opposite the second mass block, the first mass is disposed opposite the second mass, the mass of the first mass is larger than the mass of the second mass. When the MEMS inertial switch is subjected to the set acceleration, the first mass collides with the second mass under the action of the inertia, so that the second mass moves in the acceleration direction. The bistable mechanism presses the switch contact fromone steady state to the other steady state, and turns on the circuit. The MEMS inertial switch provided by the invention has the advantages of high sensitivity, strong electromagnetic interference resistance and strong mechanical vibration resistance.