How to choose a fiber optic vibration monitoring device guide

Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China

When choosing a fiber optic vibration sensing monitoring device, factors such as sensitivity, positioning accuracy, environmental adaptability, and cost-effectiveness should be comprehensively considered. Ensure that the selected device can meet the requirements of specific application scenarios, such as stable operation in strong electromagnetic interference environments or maintaining high positioning accuracy in long-distance monitoring. At the same time, the maintenance cost of the device also needs to be considered.

1、 Selection criteria for fiber optic vibration sensing and monitoring devices

1.1 Performance indicators

sensitivity
Sensitivity is an important indicator for measuring how weak vibrations can be detected by fiber optic vibration sensing monitoring devices. In some scenarios with high requirements for detecting small vibrations, such as capturing small vibrations in the early stages of earthquake waves in earthquake warning, or detecting vibrations caused by small deformations in precision mechanical structure health monitoring, high-sensitivity devices are necessary. For example, in earthquake warning applications, fiber optic sensing OPU induction devices can capture earthquake information in advance by detecting small changes in the frequency and amplitude of optical signals in fiber optic cables, which relies on the device’s high sensitivity. If the sensitivity is not sufficient, early seismic wave signals may be missed and accurate warning cannot be achieved.
positioning accuracy
The positioning accuracy determines the ability of the device to accurately determine the location of vibration occurrence. For long-distance monitoring objects, such as long-distance oil and gas pipelines, power cables, etc., devices with high positioning accuracy can quickly and accurately locate the point of intrusion or fault occurrence. For example, in the safety monitoring project of submarine cables, the distributed fiber optic vibration sensing system needs to accurately detect the precise location of the vibration around the cable, and issue accurate warnings and positioning for dangerous operations such as excavation and anchoring of large ships. Poor positioning accuracy may result in operation and maintenance personnel being unable to reach the problem site in a timely and accurate manner, increasing safety risks. Generally speaking, the positioning accuracy of long-distance distributed fiber optic vibration monitoring systems can reach 10 meters, which is ideal for many large-scale engineering monitoring applications.
Measure distance
The measurement distance is directly related to the monitoring range that the device can cover. In some large-scale infrastructure projects, such as railway lines, large bridges, etc., longer measurement distances are required. For example, when conducting safety monitoring along railway lines, fiber optic vibration sensing technology can achieve single machine dual channel 80 kilometer safety monitoring. If each meter is equivalent to one sensor, it is equivalent to integrating 80000 sensors into one fiber optic cable, which can effectively monitor longer distances along railway lines. For some large-scale oil and gas pipeline safety monitoring projects, devices with long measurement distances can reduce the number of installation points, lower costs, and ensure comprehensive monitoring of the entire pipeline.
resolving power
The spatial resolution affects the level of detailed understanding of the vibration situation within the monitoring area. Higher spatial resolution can more accurately distinguish vibration differences at different positions. For example, in some scenarios that require high structural health monitoring, such as large bridge structural health monitoring, high spatial resolution can provide detailed understanding of the vibration situation of different parts of the bridge, which helps to timely detect local structural problems. The spatial resolution of a long-distance distributed vibration monitoring system can reach ± 35 meters (the spatial resolution can be customized according to the monitoring distance), and different customized resolutions can meet the needs of different monitoring scenarios.
False alarm rate and missed alarm rate
False alarm rate and false alarm rate are key factors in measuring device reliability. In the field of security, such as perimeter defense systems in airports, prisons, and other places, if the false alarm rate is too high, it will increase unnecessary manpower and material resources consumption; If the false alarm rate is too high, it will bring security risks. An excellent fiber optic vibration sensing and monitoring device should have a low false alarm rate and leakage rate. For example, some advanced distributed fiber optic vibration monitoring systems have anti false alarm processing functions, with a false alarm and leakage rate of ≤ 5%. This can ensure safety while reducing unnecessary annoyance.

1.2 Environmental adaptability

Anti electromagnetic interference capability
In strong electromagnetic interference environments such as power systems and areas with dense electronic equipment, the anti electromagnetic interference capability of fiber optic vibration sensing monitoring devices is particularly important. For example, in the monitoring of the working status of high-voltage circuit breakers in high-voltage power grids and the monitoring of vibration and abnormal noise in substations, ordinary electronic vibration sensors may be affected by strong electromagnetic interference and cannot work properly, while fiber optic vibration sensors can accurately monitor vibration conditions because they transmit optical signals and are not affected by electromagnetic interference. This feature enables the fiber optic vibration sensing monitoring device to work stably in complex electromagnetic environments, such as substations, near electrified railways, etc., ensuring the accuracy of monitoring data.
Ability to withstand harsh environments
Including the ability to withstand harsh environments such as humidity, corrosion, and underwater conditions. In the monitoring of oil and gas facilities in the petrochemical industry, such as equipment monitoring in oil and natural gas, it is necessary for the equipment to be able to work stably for a long time due to the possible presence of corrosive gases, humidity, and other environmental conditions. The optical fiber of the fiber optic vibration sensing monitoring device itself has chemical properties such as water resistance, high temperature resistance, and corrosion resistance, and can operate for a long time in such harsh environments without worrying about the device being corroded or damaged. In the vibration monitoring of underwater structures, such as the monitoring of submarine cables, the device can also work stably to ensure effective monitoring of underwater facilities.
Temperature adaptability
The temperature varies greatly in different application scenarios, from extremely cold low-temperature environments to high-temperature industrial environments. The fiber optic vibration sensing monitoring device needs to maintain stable performance at different temperatures. For example, in outdoor facility monitoring in some cold northern regions or equipment vibration monitoring near high-temperature industrial furnaces, the device should be able to adapt to temperature changes without affecting measurement accuracy. Some fiber optic grating sensors are equipped with temperature compensation gratings, which can fundamentally eliminate the interference of temperature on the fiber optic grating sensor and ensure accurate measurement in different temperature environments.

1.3 Functional Features

Intelligent recognition capability
Intelligent recognition capability can classify and recognize different types of vibrations. In perimeter security prevention, distinguishing between vibrations caused by personnel intrusion, vehicle intrusion, or natural environmental factors such as wind blowing objects. For safety monitoring of long-distance oil and gas pipelines, it is possible to identify whether it is normal pipeline operation vibration or vibration caused by external excavation or damage. For example, a distributed fiber optic vibration sensing intelligent safety monitoring method based on deep learning can improve the intelligence level of monitoring and reduce misjudgments by constructing a sample library and using deep convolutional networks for model training to classify and recognize different types of vibration signals.
Data processing capability
Including functions such as signal filtering and spectrum analysis. The signal filtering function can remove noise interference, such as high pass, low-pass, band-pass filtering, etc. The filtering form and range can be set, and the signal can be processed according to different monitoring environments and requirements. The spectrum analysis function can convert the time domain of each signal into the frequency domain, and analyze the main and secondary components of the frequency domain signal, which helps to gain a deeper understanding of the characteristics of vibration signals and provides a basis for determining vibration types, fault diagnosis, etc. In mine microseismic signal monitoring, by designing high-sensitivity photoelectric detection circuits, signal amplification and filtering circuits, a mine microseismic monitoring system based on fiber optic sensors can be constructed to effectively process vibration signals.
Compatibility with other systems
If it is necessary to integrate the fiber optic vibration sensing monitoring device into existing monitoring or automation systems, the compatibility of the device with other systems is crucial. For example, in the automated production workshops of some large enterprises, the fiber optic vibration sensing monitoring device should be compatible with the workshop’s automation control system, data acquisition system, etc., to achieve data sharing and collaborative work. In the construction of smart cities, fiber optic vibration sensing monitoring devices should be compatible with the city’s comprehensive management system, integrating the monitored vibration data into comprehensive information platforms such as urban safety and infrastructure health management.

1.4 Reliability and Stability

service life
A longer service life can reduce the frequency and cost of equipment replacement. If the front-end passive equipment in the fiber optic vibration sensing monitoring device has a service life of 30 years, it can reduce the trouble of maintenance and equipment replacement in many long-term projects. For example, in the structural health monitoring projects of some large bridges, the service life of the bridge may be as long as several decades. The use of fiber optic vibration sensing monitoring devices with long service life can ensure continuous monitoring throughout the entire service life of the bridge, without the need for frequent equipment replacement.
stability
During long-term operation, the device needs to maintain stable performance. Whether in continuous monitoring processes or under different environmental conditions, it is necessary to be able to stably detect vibration signals and accurately output data. For example, in safety monitoring projects along railway lines, fiber optic vibration sensing technology needs to operate stably for a long time, unaffected by external environmental changes such as temperature changes, humidity changes, occasional electromagnetic interference, etc., and always maintain accurate monitoring along the railway line to ensure safe railway operation.

1.5 Cost factors

Equipment procurement cost
The procurement cost of fiber optic vibration sensing and monitoring devices with different brands and performance varies greatly. For some projects with limited budgets, it is necessary to choose devices with lower procurement costs while meeting performance requirements. For example, in some small business equipment vibration monitoring projects, if the budget is limited, fiber optic vibration sensing monitoring devices that meet performance requirements but have relatively low prices can be selected. However, for some national key projects that require extremely high safety, it may be more inclined to choose high-performance, high reliability but relatively high price equipment.
Installation and maintenance costs
The installation cost includes the installation and debugging expenses of the equipment. If the installation of the device is complex and requires professional technicians and special tools, the installation cost will increase. For example, the installation of some complex fiber optic vibration sensing monitoring systems on large bridges requires a deep understanding of the bridge structure and the accurate laying of optical fibers, which will increase installation costs. In terms of maintenance costs, such as regular equipment inspections, component replacements, etc., if the device requires frequent maintenance or maintenance is difficult, the maintenance cost will be higher. Some maintenance free or simple devices, such as long-distance distributed fiber optic vibration monitoring systems, do not require regular maintenance if there is no human damage, which can reduce long-term maintenance costs.

2、 Characteristics of different types of fiber optic vibration sensing and monitoring devices

2.1 Distributed Fiber Optic Vibration Sensor

working principle
Distributed fiber optic vibration sensor is a distributed fiber optic sensor based on coherent Rayleigh scattering. When light travels through an optical fiber, it will scatter due to the non-uniformity of the fiber. When external vibrations act on the sensing fiber, the refractive index and length of the fiber will undergo slight changes, leading to phase changes in the scattered signal inside the fiber and detecting changes in light intensity. The vibration signal usually changes relatively little. The fiber optic monitoring system uses a narrow linewidth pulse coherent light source. The object that needs to be monitored for vibration will cause a change in the phase of the fiber optic Rayleigh scattering signal in the pulse width area. The amplitude and phase changes of the vibration increase synchronously. The distributed fiber optic vibration sensing analysis system can accurately and precisely monitor the vibration that needs to be induced by detecting the difference in phase changes of the scattered light signal in the front and back stages of the object’s vibration. At the same time, it can sense different multi-point vibration events and accurately locate them.
characteristic
Continuity: It can simultaneously obtain vibration information from multiple locations on optical fibers that are tens of kilometers long, enabling continuous monitoring over long distances and large areas. For example, in the safety monitoring of long-distance oil and gas pipelines, optical fibers can be laid along the pipeline to continuously monitor the vibration of the entire pipeline and detect any abnormal vibration at any location in a timely manner. Any third-party illegal intrusion behavior, including manual excavation, vehicle intrusion, heavy machinery excavation, etc., can be detected.
Economy: Due to its distributed nature, in long-distance monitoring, compared to other types of sensor deployment methods, there is no need to set up separate sensors at each monitoring point, thereby reducing overall costs. In some large-scale infrastructure monitoring projects, such as railway lines, bridges, etc., monitoring over longer distances can be achieved by laying a fiber optic cable, reducing the number of sensors and installation costs.
Safety: Fiber optic itself has characteristics such as anti electromagnetic interference and insulation. In some flammable, explosive or strong electromagnetic interference environments, such as petroleum and petrochemical sites, near substations, etc., distributed fiber optic vibration sensors can work safely and stably, ensuring the safety of monitoring.
High sensitivity: capable of detecting small vibration changes, which is very important for monitoring scenarios that are sensitive to vibration changes, such as earthquake warning and structural health monitoring of precision equipment. In earthquake warning applications, earthquake information can be captured in advance by detecting small changes in optical signals in fiber optic cables.
High positioning accuracy: It can accurately locate the location where vibration occurs. In some scenarios that require rapid positioning of faults or intrusion points, such as submarine cable safety monitoring, airport perimeter prevention, etc., high positioning accuracy can quickly respond and take measures. For example, in the submarine cable safety monitoring project of State Grid Zhoushan Power Supply Company, accurate warning and positioning of dangerous operations such as excavation operations and anchoring of large vessels can be achieved.

2.2 Fiber Bragg Grating Sensor

working principle
Fiber Bragg Grating sensors utilize the characteristics of fiber Bragg gratings to detect vibrations. Fiber Bragg Grating is a structure in which periodic refractive index modulation is written into the fiber core. When external vibrations act on the fiber Bragg grating, it can cause axial strain, resulting in changes in the grating’s period and refractive index, thereby causing a shift in the wavelength of the reflected light. Vibration information can be obtained by detecting changes in the wavelength of reflected light. For example, in the fiber optic monitoring device for the vibration of the coal mining machine drum, the axial deformation of magnetostrictive material is used to induce the center wavelength of the fiber optic grating sensor to shift, and then the vibration acceleration of the coal mining machine drum is converted.
characteristic
Passive intrinsic safety: Fiber Bragg grating sensors are passive components that do not generate energy and do not pose safety hazards due to electrical issues. They are particularly suitable for monitoring equipment in hazardous environments such as flammable and explosive environments, such as the petrochemical industry. In the monitoring of equipment in oil and gas, its insulation and non-metallic characteristics can ensure safe use in hazardous environments.

Strong anti-interference ability: Due to the transmission of optical signals, it is not affected by electromagnetic interference and has strong resistance to environmental pollution and corrosion. In the monitoring of power equipment vibration, temperature, and other conditions in the power industry, it will not be affected by strong electromagnetic environments such as substations and can work stably.

Serial multiplexing: Multiple fiber Bragg grating sensors can be connected in series through serial multiplexing techniques such as time-division multiplexing and wavelength division multiplexing. Multiple branches can be deployed through spatial division multiplexing of multiple fibers, resulting in a low overall deployment cost for the sensing network. This feature makes it easy to increase the number of sensors and expand the monitoring range in large-scale structural health monitoring projects, such as large bridges, dams, etc., without the need for complex wiring and high costs.

Good stability: Fiber Bragg grating sensors have a low temperature coefficient and excellent long-term stability. In some long-term monitoring projects, such as long-term structural health monitoring of bridges, stable performance can be maintained, unaffected by environmental factors such as temperature, and accurate monitoring of bridge vibration and other conditions can be achieved.

High flexibility: In terms of installation, some fiber Bragg grating displacement sensors can be stretched in any direction due to the use of wire pulling, making installation and use flexible, convenient, and adaptable. Equipped with coaxial variable speed wheels internally, it can achieve a large range and is equipped with buffer springs to increase the range while avoiding direct impact on fragile bare optical fibers. In different monitoring scenarios, such as building deformation and vibration monitoring in civil engineering, flexible installation can be carried out according to actual situations.

3、 Brand comparison of fiber optic vibration sensing monitoring devices

3.1 Fuzhou Yingnuo Technology

Product Features
Our main products include vibrating optical fibers, vibrating optical cables, distributed optical fibers, and other related products. Its products may have certain technological advantages in fiber optic vibration sensing and monitoring, such as sensing performance and data processing capabilities. It has a certain degree of focus in the related product fields of fiber optic vibration sensing and monitoring, and has achieved certain results in targeted research and optimization of products.
Mainly engaged in perimeter alarm systems, vibration fiber optic alarm system hosts and other products. There may be unique product designs in the use of fiber optic vibration sensing monitoring for perimeter prevention. The host of its vibration fiber optic alarm system may integrate some advanced signal processing and alarm functions, such as the ability to quickly and accurately identify and alarm different types of intrusion vibration signals. There may be good system integration capabilities in the perimeter alarm system, which can effectively link fiber optic vibration sensing monitoring with other security equipment (such as surveillance cameras) to improve the overall effectiveness of perimeter prevention.
Market reputation and credibility. Our main products include fiber Bragg gratings, fiber temperature measurement, fiber temperature sensing, and fiber optic sensors. In the field of fiber optic vibration sensing and monitoring, the overall advantages of fiber optic sensing technology may be utilized. For example, its fiber Bragg grating technology may help improve the accuracy and stability of vibration sensors. Its products may have certain characteristics in data collection and processing, able to accurately analyze and process vibration signals, and may have certain advantages in monitoring multiple parameters (such as temperature, vibration, etc.) simultaneously. It is suitable for complex scenarios that require simultaneous monitoring of multiple physical quantities, and has gradually established a certain reputation in perimeter defense projects such as factories and residential areas. When competing with other similar brands, the technology and product advantages related to perimeter alarm systems will be its core competitiveness.

3.2 Huaguang Tianrui (Fuzhou Huaguang Tianrui)

Product Features
In addition to products related to fiber optic vibration sensing and monitoring, we also venture into fields such as fiber optic gratings and fiber optic temperature measurement. There is a wide range of technological accumulation in fiber optic sensing technology. In the field of fiber optic vibration sensing and monitoring, technological achievements in fiber optic gratings and temperature measurement have shown good performance in sensor stability, anti-interference ability, and other aspects. Its products have high precision and reliability, and can meet the requirements of different industries for fiber optic vibration sensing monitoring, such as applications in power, petrochemical and other industries.
Market reputation and credibility
It has a certain level of popularity in the market, and its fiber optic temperature measurement and related products have been applied in some industries. In the field of fiber optic vibration sensing and monitoring, as it continues to expand its business, it utilizes its existing market reputation and customer resources to promote related products. The reputation of its brand is built on its comprehensive performance in various aspects such as technological research and development strength, product quality, and after-sales service.