The SITRANS TO500 multipoint temperature transmitter is used for measuring a large number of temperatures using a very narrow fiber-optic temperature measuring lance. The system consists of the following components: the transmitter, and the measuring lances, which can each be connected to up to 48 temperature sensors on the transmitter at four channels. With up to four measuring probes, 192 measuring points can be processed at the same time by a SITRANS TO500.
The extremely thin sensor measuring probe of < 2 mm is used for measured value transmission. The system is therefore particularly suitable when the user wishes to install a very large number of measuring points in a tight space and with low thermal mass, such as in tube and tube bundle reactors or in capillary or microreactors. The fast and gap-free detection of temperature profiles enables the plant operator to optimize processes in terms of lifetime, quality and output. Local overheating is quickly and accurately detected, thereby preventing damage to the process, plant and environment.
SITRANS TO500 technology is based on fiber Bragg gratings (FBGs) which are arranged at individually defined points on the sensor probe. The transmitter sends light waves to the fiber-optic sensors and evaluates the reflected portions. In the transmitter, light is generated in the wavelength of 1500 to 1600 nm and output to the sensor measuring probe by means of a continuously tunable laser light. Each fiber Bragg grating reflects light of a defined wavelength. The wavelength reflected by the grating varies depending on the temperature. The reflection at the FBGs is thus a measure of the temperature at the respective measuring point. A gas cell with fixed absorption line serves as a reference in the SITRANS TO500 and the wavelength determination is continuously adjusted by it.