This paper presents a temperature monitoring system for an electrical transmission cable utilizing a global mobile service (GSM)-based unclad fibre sensor. The developed system consists of GSM module, Arduino controller, unclad plastic optical fibre (POF) sensor, light emitting diode (LED) and photodetector. The unclad POF sensor was chosen due to its immunity towards electromagnetic interference as well as its high sensitivity performance. In this work, the transmission cable hazardous temperature is set at 70oC, which is the maximum operating temperature value provided by the National Electrical Code (NEC) NFPA 70. For system characterization, temperature of the cable was varied from 30oC to 70oC. Photodetector output voltage for this temperature variation were recorded at 660 nm and 770 nm operating wavelength. The recorded data shows that the sensor sensitivity performances at 660 nm wavelength are found superior than 770 nm wavelength, which are 0.9710mV/oC and 0.9699mV/oC respectively. As for the GSM communication system, the system was characterized based on accuracy of the information send via GSM text message and its delay. The developed system offers economical and practical monitoring system to be adopted for transmission cable temperature monitoring in remote area.
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