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An application of FBG accelerometers for monitoring pantographs of underground trains

The use of FBG based sensors for the monitoring of the pantograph-catenary interaction is very attractive due to the insensitivity of fiber optic sensors to the electromagnetic disturbances and due to their ability to be electrically insulated. In fact, the monitoring of pantograph-catenary interaction with traditional sensors needs a complicated set-up to electrically insulate sensors, to power the signal conditioning devices and to transmit the signal to the data acquisition system, and to avoid interferences between the measurement signals and electromagnetic disturbances typically generated by continuous sparking and eventual arcing phenomena caused by contact loss between the pantograph collector and the contact wire of overhead line. In this work the application of a commercial FBG accelerometer on a pantograph of an underground train, instrumented for experimental in-line tests, is analyzed. In particular, a comparison between a traditional capacitive accelerometer and a FBG accelerometer is presented to highlight the proper working of the fiber optic sensor during in-line tests and to take the use of this kind of fiber optic sensor into consideration for monitoring aim in the pantograph-catenary interaction, simplifying the measurement set-up. The first results show that this approach is promising.