Fibre Optic Linear Heat Detection System

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With the requirement of urban Infrastructures, the temperature monitoring becomes the core necessity of any public structure whether its Thermal power Plant, Metro, Hospital and Data centres.

This technology makes use of fiber optic sensor cables, typically over lengths of several kilometers, that function as linear temperature sensors. The result is a continuous temperature profile along the entire length of the sensor cable.

DTS utilizes the Raman effect to measure temperature. An optical laser pulse sent through the fiber results in some scattered light reflecting back to the transmitting end, where it is analyzed. The intensity of the Raman scattering is a measure of the temperature along the fiber. The Raman anti-Stokes signal changes its amplitude significantly with changing temperature, the Raman Stokes signal is relatively stable.

The position of the temperature reading is determined by measuring the arrival timing of the returning light pulse similar to a radar echo. This method is called OTDR (Optical Time Domain Reflectometry).

The DTS Technology is also known as Raman OTDR or Raman OFDR (Optical Frequency Domain Reflectometry). The Raman effect is named after the Indian physicist Sir Chandrasekhara Venkata Raman (1888 – 1970), who discovered that when light traverses a transparent material, some of the reflected light changes in wavelength. This ground-breaking work in the field of light scattering earned him the Nobel Prize for Physics.

The Raman OTDR technology with some unique techniques such as code correlation technology and a single receiver design for both Stokes and anti-Stokes. This approach results in outstanding system reliability (immune to the effects of strain, which can lead to anomalous readings), accurate measurements and high performance, for which AP Sensing is known.

Sensor cables

Sensor cables are available with metal tubing or metal-free, with tube-in-tube or armored stainless steel configurations, and with a wide range of appropriate sheathings, for example, FRNC (flame retardant non-corrosive).

Fibers need to be selected for the applicable temperature range and sensing technology. Sensing fibers for normal temperature ranges utilizing acrylate coating, cryogenic and higher temperature ranges use polyamide coating and extra high-temperature applications may require metalized fibers such as copper alloy coatings or gold-coated fibers.

Sensor cables are available with MM (multimode) and SM (single mode) fibers or a combination of both, as well as embedded copper wires for hybrid use.

Our team of application engineers will work with you on the application requirements and will work with our cable manufacturing partners to find a balance between costs, thermal conductivity and ruggedness.