Please consult with the fluorescent fiber optic temperature sensor

<> Huaguang Tianrui fluorescent fiber temperature measurement technology can solve the problem of hot spot temperature measurement of power equipment, it has the characteristics of high voltage resistance, high insulation and anti-electromagnetic interference, which is the technical development direction of hot spot temperature measurement of electrical equipment in power system in the future. Optical fiber temperature measurement technology mainly includes distributed optical fiber temperature measurement technology and infrared temperature measurement technology, wherein, infrared temperature measurement technology can only measure the temperature of the surface of electrical equipment, can not measure the hot spot temperature inside the electrical equipment, and the installation mode of fluorescent optical fiber temperature measurement technology is consistent with the conventional electrical signal temperature sensor, can be directly embedded in electrical equipment, so it has strong convenience of use.

The SR-G fluorescent optical fiber temperature measurement device system is divided into two parts: the bottom temperature measurement unit and the upper computer system, in which the bottom temperature measurement unit is composed of transformer, high-voltage open light cabinet, high-voltage master, cable head and other multi-channel temperature measurement optical fiber temperature measurement devices, and the upper computer system is composed of the main control room and on-site monitoring device. The optical fiber temperature measurement device adopts RS485 interface communication mode, which is converted into optical fiber communication signal through the photoelectric converter, and realizes remote communication with the host computer system composed of remote main control room and on-site monitoring device, so as to improve the reliability and anti-interference ability of the communication system.

Based on the fluorescent fiber temperature measurement technology, a complete temperature measurement scheme is designed in combination with substation equipment. After experimental verification, the temperature measurement range of the temperature measurement system is -40 200, and the accuracy is 1, which meets the actual requirements. The temperature measuring device has the characteristics of low cost, stable performance, strong practicability, fast and stable response, and simple operation.

The whole system operates reliably in harsh environments such as high temperature, high pressure, strong magnetic field, flammable and explosive.

The working principle of the fiber optic temperature sensor is as follows: in the low temperature area (below 400), the radiation signal is weak, and the system turns on the light-emitting diode (LED) to make the fluorescence temperature measurement system work. The light-emitting diode emits modulated excitation light, which is coupled to the branch end of the Y-type fiber through a condenser, and the Y-type fiber is coupled to the fiber temperature sensing head through a fiber coupler.

The fluorescence signal is emitted by the optical fiber and emitted by the excitation of the excitation light, and the fluorescence signal is exported by the optical fiber and emitted from the other branch end of the Y-shaped fiber through the fiber coupler, which is received by the photodetector. The optical signal output by the photodetector is amplified and processed by the fluorescence signal processing system to calculate the fluorescence lifetime and obtain the measured temperature value. And in the high temperature area (above 400), the radiation signal is strong enough, the radiation temperature measurement system works, and the LED is turned off.

The radiation signal is output through the sapphire fiber and through the Y-shaped fiber, which is converted into an electrical signal by the detector, and the system calculates the measured temperature by detecting the radiation signal intensity.

The end of the optical fiber sensing head is doped with Cr3+ ions to achieve fluorescence emission during light excitation. The length of the doped part of the fiber is 8 10 mm. The outer surface of the end optical fiber is also coated with a black body cavity for radiation temperature measurement.

At this time, the ratio of the length to the diameter of the black body cavity of the optical fiber is greater than 10, which can meet the requirement of constant apparent emissivity of the black body cavity). It is worth noting that it is very important to avoid or reduce the mutual interference between the fluorescence emission part and the thermal radiation part to ensure the performance of the whole system.

After analysis, it can be found that this interference is mainly manifested as:

1) the effect of the radiation background signal on the detection accuracy of fluorescence lifetime in the fluorescence signal, 2) the effect of optical fiber surface coating on the fluorescence intensity, and 3) the effect of Cr3+ ion doping in the fiber on the thermal radiation signal of the black body cavity.

Fluorescence temperature measurement system: The end of the optical fiber is coated with a fluorescent substance, and after a certain wavelength of light excitation, the fluorescent substance is stimulated to emit fluorescent energy. Since the stimulated radiation energy decays exponentially, the time constant of the attenuation varies depending on the temperature, and the temperature at the measurement point is obtained by measuring the attenuation time.

This method is a single-point temperature measurement of optical fiber. Using the principle of afterglow time and temperature correlation of rare earth special fluorescent substances, the temperature information is obtained through afterglow time, and this technology has been verified to be used to monitor the temperature of ultra-high voltage (750kV) transformer windings. The sensor is small in size, high in long-term reliability, moderate, and can not only realize the configuration of single-sided cabinets, but also build a temperature monitoring system, and the construction and commissioning process is convenient and fast.

The disadvantage is that the length of the sensor is basically about 15m, and the temperature analysis can only be placed in the local temperature interrogator, and then the temperature signal after analysis is transmitted to the central control through the adapter optical fiber or cable. The adjustment of the settings for replacing the fiber optic sensor after damage is cumbersome, because the channels of the fiber optic sensor and the temperature interrogator of each channel are one-to-one, and the channels are not interchangeable. The manufacturer needs to produce a fiber optic sensor separately before it can be installed and used after it is set and adjusted.

It is not recommended to use fluorescent fiber optic sensors in scenarios with oil, as oil will corrode the probe to a certain extent, which will affect the service life and measurement accuracy of the probe.

A fluorescent fiber temperature sensor consists of a multimode fiber and a fluorescent object (membrane) mounted on top of it. Fluorescent substances are stimulated to emit fluorescent energy after being excited by light at a certain wavelength (stimulus spectrum). After the excitation is withdrawn, the persistence of fluorescence afterglow depends on factors such as the characteristics of the fluorescent substance, the ambient temperature, and so on.

This excited fluorescence is typically attenuated exponentially, and we call the time constant of attenuation the fluorescence lifetime or fluorescence afterglow time (ns). We found that the fluorescence afterglow attenuation was different at different ambient temperatures. Therefore, by measuring the lifetime of fluorescence afterglow, it is possible to know the ambient temperature at that time.

The core technology of the fluorescent fiber optic temperature sensor lies in its fluorescent substance and the corresponding simulation algorithm. The technical principle and product structure are very simple, the temperature measurement phosphor we use is calcined at a high temperature of 1200 degrees, which has an extremely long life and stable and reliable working characteristics, which is very suitable for large-scale industrial mass production, so as to quickly realize a wide range of applications in the industrial field.

Composition and working principle of fluorescent fiber temperature measurement fire monitoring system

Once the temperature of the switchgear monitoring point is too high, it can identify and alarm immediately, leaving enough time for the staff to take measures to reduce the temperature of the switchgear, ensure the normal operation of power production, avoid fire accidents and large-scale power outages, and prolong the service life of the switchgear.

The fluorescent fiber optic thermometer IF-C has a qualitative improvement in the performance level of fire detection and alarm of the switchgear, effectively overcomes the difficulty of real-time and accurate temperature measurement of the switchgear during operation, and greatly improves the ability to apply this technology to improve fire early warning and eliminate fire hazards. At the same time, the fluorescent optical fiber temperature measurement fire monitoring system can also be applied to other fire danger places that need to monitor temperature changes in real time, so as to realize real-time early warning of fire and improve the fire prevention and control ability of the place.

Summary. Hello, dear, the fluorescence sensor is affected by temperature because the detection sensitivity of the fluorescence sensor depends on the detection of the ambient temperature, the higher the temperature, the more volatile the specific substance, the easier it is to be detected by the fluorescence sensor, so the detection system is often heated when the detection work is carried out. Fluorescence sensors detect specific substances by using fluorescent substances coated on glass substrates that fluoresce-quench specific substances.

Hello, dear, the fluorescence sensor is affected by temperature because the detection sensitivity of the fluorescence sensor depends on the detection environment temperature, the higher the temperature, the more volatile the specific substance, the easier it is to be detected by the fluorescence sensor, so the detection system is often heated when the detection work is carried out. Fluorescence sensors use fluorescent substances coated on glass substrates to detect specific substances by fluorescently quenching them.

The optical fiber temperature sensor temperature measurement system has great application potential in the fields of military equipment, electric power industry, machinery industry, automobile industry, iron and steel industry, petrochemical industry, food and feed due to its advantages of anti-electromagnetic interference, fire-proof, explosion-proof, intrinsic safety, small size, and small impact on the measured temperature field. At present, there are many types of optical fiber temperature sensors, mainly including fiber grating temperature sensors, fiber optic FAB r y perot interferometric temperature sensors, fiber fluorescence temperature sensors, distributed fiber fiber temperature sensors, etc. These optical fiber temperature sensors have been widely used because of their good sensing performance, among which the fluorescent optical fiber temperature sensor of Fuzhou Huaguang Tianrui has the advantages of simple structure, high sensitivity, and customizable sensitivity and measurement range.

1. In the electromagnetic radio frequency environment, the traditional temperature measurement method cannot work normally due to serious interference;

2. There are particularly high requirements for accuracy, sensitivity, or life, stability and reliability;

3. The installation environment is narrow, and there are special requirements for the size of the sensor;

4. Flammable, explosive, corrosive environment, special requirements for safety and corrosion resistance.

5. Lightning strikes, wild and other harsh environments.

6. The test site energy is inconvenient.

The pure fiber optic probe is intrinsically safe, high-voltage insulation, and anti-electromagnetic interference;

The system works stably and reliably, without drift, and there is no need for calibration and calibration throughout the life;

Modular design, flexible networking at will, unlimited expansion at any time, no waste of resources;

Digital and analog output, easy to carry out automatic real-time control and data management;

The probes and demodulators are compact and flexible, making them easy to install and maintain.