fiber bragg grating for temperature sensing Electrical fire monitoring system

Fiberoptisk temperatursensor, Intelligent övervakningssystem, Tillverkare av distribuerad fiberoptik i Kina

The electrical fire monitoring system, automatic fire alarm system, and leakage fire alarm system, although to some extent filling the gap of rapid response and fire prevention in the event of a fire, cannot solve the problem of excessive contact resistance and heating at the internal connection points of the switchgear due to oxidation, looseness, and pollution during operation, especially the problem of high temperature rise at the connection points between the feeder cable and the busbar or switch due to overload, thus burying fire hazards.

The Design Specification for Fire Automatic Alarm System states that the temperature measurement system should mainly be installed in key heating parts such as cable joints, and contact temperature measurement should be used for lines below 1kV, and fiber optic grating temperature measurement should be used for lines above 1kV. In fact, fiber optic grating temperature measurement systems can meet the requirements of contact temperature measurement, and can also be applied in high-voltage environments with excellent insulation performance.

Designers are most concerned about the temperature of the internal connection points of the switchgear, and hope to be able to obtain real-time temperature information in order to promptly handle faults. Emellertid, conventional temperature measurement methods mainly use temperature sensors, infrared imaging devices, and temperature sensing cables, which cannot fully meet this requirement, mainly reflected in the following aspects:

1) Conventional temperature measurement methods such as thermocouples, thermistors, and semiconductor temperature sensors are not recommended for use inside high and low voltage cabinets due to their inherent electrification or the need for metal wires to transmit signals, and their insulation cannot be guaranteed.

2) The handheld infrared thermal imager must maintain a distance from the object being tested, which is a non-contact temperature measurement method that requires manual operation and cannot achieve uninterrupted online measurement. Dessutom, the temperature data measured is the thermal radiation value of the object surface, which is easily affected by the environment and has poor authenticity.

High and low voltage switchgear are all “sealed” type, and when the equipment is in operation, the small room is usually closed. Ytterligare, there are many live conductors inside the cabinet, making manual inspection very difficult.

Temperature sensing cable temperature measurement is a linear temperature measurement method that cannot locate the temperature or temperature changes at a certain point, and therefore cannot be applied to temperature measurement at switch cabinet connection points.

The characteristics and advantages of fiber optic grating temperature measurement systems

As is well known, when the system or equipment is overloaded, the circuit breaker needs to accumulate heat before it can act, which is a long process. When the circuit breaker refuses to act or fails to act, it can cause harm to equipment such as busbars, Växlar, and cabinets, and even lead to a fire. The fiber optic grating temperature measurement system can meet the requirements of contact temperature measurement and can measure the temperature of the monitored object in real time without power outage. It can indirectly monitor the operation of equipment or distribution circuits, allowing management personnel to know abnormal temperature information in the first time, eliminate fire hazards in the first time, and improve automation and response speed.

Introduction to the working principle of fiber optic grating temperature sensor for temperature measurement

The fiber optic grating temperature measurement system uses fiber optic as the transmission medium, utilizing the temperature sensitivity of Bragg gratings and the principle of light reflection, to detect real-time temperature changes in the heating parts of power facilities in the power system, and perform multi-point temperature data collection, calculation, display, diagnosis, and alarm.