Overheating fault, insulation fault and mechanical fault are important reasons for power system safety accidents. The frequency of overheating faults accounts for more than 50% of the total number of accidents. Abnormal temperature rise of high-voltage power distribution equipment will inevitably cause contact resistance increase, equipment aging, insulation decline, conductor burning, serious will cause ground short circuit, secondary to interphase short circuit, resulting in equipment damage, interruption of power supply, and even cause serious personal, power grid and equipment accidents.

These vicious accidents not only bring serious economic losses to electric power enterprises, but also may cause immeasurable adverse social impact. Due to the frequent occurrence and growth of overheating faults, 11.7.2 on "strengthening the monitoring of the temperature rise of operating equipment" in "18 major anti-accident measures of the State Grid Corporation of China" (for trial implementation) clearly proposes that temperature rise monitoring should be carried out on components prone to "overheating" faults. At present, the development of society has also put forward higher safety and quality requirements for the entire power supply link, and the monitoring of the operating temperature of the distribution device is also an important topic in the construction of smart grid. Therefore, this report believes that it is necessary to configure relevant temperature rise online monitoring devices in power distribution devices, so that power companies can take targeted preventive measures to improve the level of safe power supply.

With the development of power grid and the improvement of equipment technology, closed 10kV and 35kV system switch cabinets have been widely used in the power grid. The miniaturization, compact design and changes in the power environment have made the internal overheating of the switch cabinet a common abnormal state in the use of the switch cabinet.

The system adopts advanced fluorescent optical fiber temperature sensing technology, which has the advantages of high voltage resistance, no electromagnetic interference, intrinsic safety, long-term reliability, easy expansion, etc., and can monitor the temperature of box transformer, high voltage switch cabinet, ring network cabinet, outdoor and underground cable joints of power generation and power supply system in real time.

Introduction to the principle of fluorescence optical fiber temperature measurement
The fluorescent optical fiber temperature sensor technology has made a major breakthrough in the anti-electromagnetic interference, insulation, reliability and stability, corrosion resistance, accuracy, life, size and other aspects of the temperature sensor. The technical problems of temperature monitoring and monitoring that have plagued related industries for a long time in special industrial environments such as high voltage, electromagnetic interference and chemical corrosion are solved. The process control, safety monitoring, improvement of energy efficiency and production efficiency of equipment use in the above-mentioned special industrial environment provide advanced concepts and technical means.
    
Fluorescence temperature measurement: some substances absorb and store energy from the outside world and enter the excited state. When it returns to the ground state from the excited state, the excess energy is emitted in the form of electromagnetic radiation, which is called fluorescence. A substance having such characteristics becomes a fluorescent substance. The fluorescent temperature sensing probe is composed of a multimode fiber and a fluorescent substance mounted on top of it. After the fluorescent substance is excited by light of a certain wavelength (excited spectrum), the excited substance emits fluorescent energy. The persistence of the fluorescence emission after the excitation disappears depends on the properties of the fluorescent substance, environmental factors, and the lifetime of the excited state. This excited fluorescence usually decays exponentially, and the time constant of decay is called the fluorescence lifetime or fluorescence fading time. At different ambient temperatures, the fluorescence lifetime is also different, so by measuring the length of the fluorescence lifetime, you can know the ambient temperature at that time.